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January 1980 * aS I 7 >
. wae & F

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Shock story:
size yourself up
with a micro

q @
Basan

Review: Haas
pocket micro?

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“| NOW 2
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ay
925 2024
03 TS ANSWER

Sample catalogue prices:
“System Two computer 1995
*System Three computer 3293
*Z-2H computer 4998

Extra 64K memory 893

3101 visual display unit 1147

3355 daisywheel printer 2297

HDD 11-mbytes hard

disc 4022
ANSI Cobol compiler 55

ANSI Fortra nea 55
16K extended: 55
Word processing system 5
Database management 5
Macro relocating

assembler =
Prices exclude VAT and

OeIVi

With our in-depth experience and total Micro Centre
commitment to the reliable Cromemco range

we are Cromemco’s leading UK distributor.
Rely on us, as many others do, for expert
support with your routine or special
micro-computer applications.

Photo features Cromemco System 3 computer, 3101 VDU. and 3355 daisywheel printer.

MicroCentre also supply pétipherals, applications sofware, and multi-user
' timesharing systems; a PROM programmer; analogue-digital interface; and
h more. On site maintenance can be arranged throughout the UK.

nicro, S-100 bus (21 slots), 64K

c. CP/M compatible
A es

Complete Micro Systems Ltd.
132 St. Stephen Street,
Edinburgh EH3 5AA.

Tel: 031-225 2022.

Look out for us at Compec ‘79, stand no. 756

@ Circle No. 101

actical

ompyting

Editor
Peter Laurie

Technical Editor
Nick Hampshire

Staff Writer
Duncan Scot

| Production
Martin Hayman

Editorial Secretary
Susie Manning

Advertisement Department
Tom Moloney

Tina Roberts

David Lake

Publishing Director
Christopher Hipwell

Editorial: 01-261 8752
Advertising: 01-261 8000

Practical Computing is
published by IPC Electrical
Electronic Press Ltd,
Dorset House, Stamford
Street, London SEI 9LU.
Tel: 01-261 8000
Telegrams/Telex: 25137
BISPRSG

and printed by

Eden Fisher Ltd,
Southend-on-Sea.

Distributed by

IPC Sales and Distribution Ltd,
40 Bowling Green Lane,
London, ECIR ONE.
Typesetting & Artwork

by Bow-Towning Ltd,
London ECI.

Subscription Rates:

Single copy: 50p.
Subscriptions: U.K.,

£6 per annum

(including airmail postage).
Europe (excluding U.K.), £12;
Elsewhere In the world: £18.

Subscription Enquiries:
Subscription Manager

IPC Business Press (S.and D.)
Ltd.

Oakfield House,

Perrymount Road,

Haywards Heath,

Sussex RH16 3DH.

Tel: 0444 59188.

©IPC Business Press Ltd 1979
ISSN 0141-5433.

Every effort has been made to
ensure accuracy of articles and
program listing, Practical
Computing cannot, however,
accept any responsibility
whatsoever for any errors,

CONTENTS

45 Editorial /What happens next?

47 Feedback/ In defence of COBOL; competition winners; reliability for
the TRS-80

50 Printout / Computer chief hits out at cowboys; new Tandy for 1980

52 Has the pocket computer arrived? / Vincent Tseng peeks at the
H-P 41C: could this be the forerunner of the portable micro?

54 At home on the range/ Martin Collins reviews the Texas TEI system

56 Whose hand rocks the cradle? / As hospital budgets shrink, one

department has come up with a novel and time-saving micro application for wards.

Report by Duncan Scot

58 Single-cell movements tracked by computer / Part 2 of
Practical Computing ’s account of work in progress at the University of London’s
image processing group

63 Getting started / The agony of one man’s way through the hardware
jungle

66 Hoover by Rex Malik/ A scenario for the future: earth ruled by
intelligent satellites

7 l Shock story! Size yourself up with a micro/Chris Smith
describes how to use a micro to measure your pain responses

79 Upsetting the Applecart/ David Hebditch interviews Eurapple chief
Andre Souson and gets some tantalizing glimpses of new fruit

84 Speak, memory .../ A. C. Kilgour on the latest developments in
memory which allow micros to ‘draw’ the real world

92 Pet Corner
94 Tandy Forum
95 Apple Pie
6502 Special
97 Life forms unlimited / Steve Thomas’s version of the game in Basic
l 00 Book reviews / Getting Acquainted with Microcomputers

103 A brief encounter with monitor program software /
R. D. Hodgson describes how to squeeze the last drop out of the CPU

l 05 Cut conversion fiddle with assembler program / Take the
sweat out of machine code programming

l 10 Buyers guide/ Your market update

l 18 Diary

l 47 Glossary / The A-Z of what it means

we)

rercom ._ SOFTWARE

This is how your business appears on the screen.
6800
Approx 60 entries update require only 1-2 hours weekly and % Sy
your entire business is under control. ono”

* PROGRAMS ARE INTEGRATED SELECT FUNCTION BY NUMBER

1=ENTER NEW NAMES/ADDRESSES 13= PRINT CUSTOMER STATEMENTS
2=* ENTER/PRINT INVOICES 14= PRINT SUPPLIER STATEMENTS
3=* ENTER PURCHASES 15=PRINT AGENTS STATEMENTS

=* ENTER AIC RECEIVABLES 16=PRINT QUARTERLY TAX STATEMENTS
5=* ENTER AIC PAYABLES 17=PRINT WEEK/MONTH SALES
6=ENTER/UPDATE STOCKS REC’D 18= PRINT WEEK/MONTH PURCHASES
7=ENTERORDERSREC’D 19= PRINT YEAR AUDIT
8=EXAMINE/UPDATE BANK BALANCE 20=PRINT PROFIT/LOSS ACCOUNT
9=EXAMINESALESLEDGER- 21=UPDATE ENDMONTH FILES
10 =EXAMINE PURCHASE LEDGER 22=PRINT CASHFLOW ANALYSIS
11=EXAMINE INCOMPLETE RECORDS 23=ENTER PAYROLL
12=EXAMINE PRODUCE SALES 24= RETURN TO BASIC
WHICH ONE (ENTER 1 TO 24)
EACH PROGRAM GOES IN DEPTH TO FURTHER EXPRESS YOUR REQUIREMENTS.
FOR EXAMPLE (9) ALLOWS: a. list all sales; b. monitor sales by stock code; c. invoice search;
d. amend ledger files; e. total all sales.
BUSINESS PROGRAM VERSION 1 BUSINESS PROGRAM VERSION 3
(VERBOSE SIMPLE LANGUAGE AND UNITARY (SPACE SAVING AND MULT! MODE AND
FILE HANDLING) FUNCTION PROGRAMS)

BUSINESS PROGRAM VERSION 2 BUSINESS PROGRAM VERSION 5
(MORE INPENETRABLE VALIDATIONS AND (INCLUDING PAYROLL, YEAR AUDIT, PRO’
PROTECTION) LOSS; CASHFLOW)

MULTI-MODE 1, MULTI-FUNCTION, 12 STRING MULTI-MODE 2, MULTI-FUNCTION, 12 STRING
HANDLER HANDLER & NUMERIC COMBINER

7h Ay

: HARDWARE

rs
e PET 2001 SERIES ¢ COMPUTERS
PET Computer 2001 32K

PET Printer 3022 Tractor Feed Intertec Superbrain
PET Floppy Disks 2040 Dual Z-80A Vector Interrupt, 64K RAM

PET IEEE Cables pws 1K 2708 PROM Bootstrap, Two
Double-Density 5in. Floppy Disks

e TERMINALS

Hazeltine 1510 Industrial Micro Systems 2-80 System
Interlube Video Terminal 48K Expands to 594K; Twin D/D Disk
Soroc 10120 included. Expands to 10 Meg and pro-
grams are CPM compatible £2,500
e PRINTERS
Smoke Signal 6800 System
Teletype 43 Printer ................. : 32k Expandable + Twin D/S
Centronics 779 Printer

Please telephone for appointment — Tony Winter 01-636 8210

G.W. Computers Ltd., 89 Bedford Court Mansions, Bedford Avenue, London WC1.

¢ Circle No. 102
4 PRACTICAL COMPUTING January 1980

Z-2H
Computer ystem_’

A B

11 Megabytes of hard disc storage in a fast, new, table-top computer.
@ Fast Z80A 4MHz processor CAMBRIDGE CAMBRIDGE COMPUTER STORE, Cambridge (02231 68155

: ‘ CAMBERLEY MICROBITS, Camberiey Surrey 10276) 34044
=| ILFORD THE BYTE SHOP. | c 01-55
@ 11-megabyte hard disc drive ee eats
- - LEEDS HOLDENE LIMITED. Leeds 10532) 459459
@ Two floppy disc drives aso st winslow Cheshire 10625) 529486

LONDON DIGITUS LIMITEO, London W101 6360105

@ 64K RAM mem ory LUTON ISHERWOODS. Luton Beatordshire (0582) 424851

MANCHESTER MICROCOMPUTERMART. Manchesler (061-832) 2269

+ 4 i al West Park Lee (0532) 788466
@ RS-232 serial interface NEWBURY NEWBEAR COMPUTING STORE, Newbury Berks (0635) 30805
0 al Stockpor! Cheshire (061-491; 2290

1 j NEWPORT MICROMEDIA. Ni w 1 Gwent (0633) 50528
@ Pri nter interface NOTTINGHAM COMPUTERLAND LIMITED. Notingnam (0602) 40576.
; } Iso al Birmingh (023-622) 7149
@ Extensive software available so ei anchestor 1061-894) 0220
Giasgow (041 332) 2468
. SHEFFIELD HALLAM COMPUTER SYSTEMS, Sheftielc (0742) 663125
Contact us direct or call your nearest Comart SOUTHAMPTON XITAN SYSTEMS LIMITED. SEtiRSERTOR TOSI oer

dealer

comart specialists in microcomputers

Comart Ltd., PO. Box 2, St. Neots, Huntingdon, Cambs, PE19 4NY. Tel: (0480) 215005 Telex: 32514
| ® Circle No. 103

PRACTICAL COMPUTING January 1980 5

Even More!

Super software from the world’s leading microsoftware supplier.

with / Manual

Software
DIGITAL RESEARCH Manual [os

CP/M* FDOS — Diskette Operating System complete with
Text Editor, Assembler. Debugger. File Manager and system
utiities. Available for wide variety of disk systems including
North Star. Helios |, Micropolis. COM (all systems) and Altair
Supports computers such as Sorcerer. Horizon. Sol System III
Versatile. Altair 8800. COMPAL-80. DYNABYTE DB8/2. and
\COM Attache Specify desired configuration £75/£15

MAC — 8080 Macro Assembler. Full Intel macro definitions
Pseudo Ops include RPC. IRP, REPT, TITLE, PAGE. and
MACLIB. 2-80 library included. Produces Intel absolute hex
output plus symbols file for use by SID (see below) £55/£10

SID — 8080 symbolic debugger. Full trace. pass count and
break-point program testing system with back-trace and histo-
gram utilites. When used with MAC, provides full symbolic
display of memory labels and equated values £45/£10

TEX Text formatter to create paginated. page-numbered
and justified copy from source text files, directable to disk or
printer £45/£10

DESPOOL -- Program to permit simultaneous pnnting of
data from disk while user executes another program from the
console £30/£7

MICROSOFT

Disk Extended BASIC — Version 5, ANSI compatible with
long variable names, WHILE/WEND, chaining, variable length
file records £155/£15

BASIC Compiler — Language compatible with Version 5
Microsoft interpreter and 3-10 times faster execution. Pro-
duces standard Microsott relocatable binary output. Includes
Macro-80. Also linkable to FORTRAN-80 or COBOL-80 code
modules £195/£15

FORTRAN-80 — ANS! ‘66 (except for COMPLEX) plus
many extensions. Includes relocatable object complier. linking
loader, hbrary with manager. Also includes MACRO-80 (see
below) £205/£15

COBOL-80 — ANSI ‘74 Relocatable object output. Format
same as FORTRAN-80 and MACRO-80 modules. Complete
ISAM interactive ACCEPT DISPLAY. COPY. EXTEND

£325/£15

MACRO-80 — 8080/Z80 Macro Assembler. Intel and Zilog
mnemonics supported. Relocatdble linkable output. Loader.
Library Manager and Cross Reference List utilities included

£75/£10

EDIT-80 —- Very fast random access text editor for text with or
without line numbers. Global and intra-line commands sup-
ported. File compare utility included £45/£10

XITAN (software requires Z80** CPU)

Software
i 7
EIDOS SYSTEMS Mo / a
KISS — Keyed Index Sequential Search. Offers complete
Multi-Keyed Index Sequential and Direct Access tile manage-
ment. Includes built-in utility functions for 16 or 32 bit arithme-
tic. string integer conversion and string compare. Delivered as

a relocatable linkable module in Microsoft format for use with
FORTRAN-80 or COBOL-80. etc. £275/£15

K BASIC Microsoft Disk Extended BASIC with all KISS
facilities. integrated by implementation of nine additional com-
mands in language. Package includes KISS.REL as described
above. and a sample mail list program £495/£30

MICROPRO

Super-Sort | — Sort. merge. extract utility as absolute
executable program or linkable module in Microsoft format.
Sorts fixed or variable records with data in binary, BCD.
Packed Decimal, EBCDIC. ASCIl. floating. fixed point. expo-
nential. field justified, etc. etc. Even variable number of fields

per record! £125/£15
Super-Sort Il — Above available as absolute program gol
£105/£1

Super-Sort Ill — As I! without SELECT’EXCLUDE
£75/€15

Word-Master Text Editor — In one mode has super-set of
CP/M's ED commands including global searching and replac-
ing, forward and backwards in file. In video mode, provides tuil
screen editor for users with serial addressable-cursor terminal

€75/f15

Word-Star Menu driven visual word processing sys-
tem for use with standard terminals. Text formatting performed
on screen. Facilities tor text paginate. page number. justify.
center. underscore and PRINT. Edit facilities include global
search and replace. read wnite to other text files. block move.
etc. Requires CRT terminal with addressable curso: position-
ing. £255/£15

GRAFFCOM SYSTEMS

PAYROLL — Designed in conjunction with the spec for PAYE
routines by HMI Taxes. Processes up to 250 employees on weekly
or monthly basis. Can handle cash, cheque or bank transfer
payments plus total tracking of all year to date figures. Prints emp
master. payroll log, payslips and bank giros, Requires CBASIC-2

.£475/£15

COMPANY SALES — Performs sales accounting function.
Controls payments of invoices and prints sales ledger and aged
debtors report. Suitable for any accounting period. Comprehen-
sive VAT control and analysis of all sales invoices. Requires
CBASIC-2. ,£425/£15

COMPANY PURCHASES -—- Performs purchase accounting
function. Controls invoices, credit & debit notes. Prints purchase
ledger, aged creditors report and payment advices. Comprehen-
sive VAT control and analysis of all purchases. Interfaces with the

Z-TEL — Text editing language. Expression evaluation itera- 3
tion and conditional branching ability. Registers available for NAD system. Requires CBASIC-2 £425/£15
text and commands. Macro command strings can be saved on STOCK CONTROL

Seri enie-use pil Maintains stock records, monitors stock levels to ensure optimum
ASM Macro Assembler — Mnemonics per Intel with Z-80 ex- stock holding. Details include stock desc., product code, unit, unit
tensions Macro capabilities with absolute Intel hex or relocat- A price, quantity on hand/on order/minimum. Stock analysis reports
able linkable output modules. New version 3 with added can be weekly, monthly, quarterly etc. Interfaces with Order Entry

£40/£12 Invoicing system. Requires CBASIC-2 : £325/£15

LINKER — Link-edits and loads ASM modules... £40/£12 (J ORDER ENTRY & INVOICING _ a.

; Performs order entry and invoicing function. Handles invoices for
Z-BUG debugger — Trace, break-point tester. Supports dec- ati Services and consumable items, part orders and part quantities.
imal, octal and hex modes. Dissassembler to ASM mnemonic <" Sales Analysis report shows sales movements and trends for
$et. Emulation technique permits full tracing and break-point s user-defined period. Interfaces with Stock Control, NAD and

features

Jey

support through ROM ie . £45/£12 Company Sales systems. Requires CBASIC-2........ €325/£15
(1 TOP Text Output Processor — Creates page-numbered. jus- OO NAD— Complete control of all your names & addresses including
tified documents from source text files £40/£12 suppliers, clients, enquiries etc. Assign your own coding system

and select alt output via the report generator. Will print anything
from mailing labels to directories. Requires CBASIC-2.

OC A4 package includes Z-TEL. ASM. LINKER. Z-BUG. TOP
, £225/£12

£155/£30

47? Mass tastes td 1 Dicptat Rees
“280 is a trademark ol Zilog. inc

EFFECTIVE 1 OCTOBER 1979

|
|
|
L..

6 PRACTICAL COMPUTING January 1980

Software for most popular 8080/Z80 computer disk systems including
NORTH STAR HORIZON, VECTOR MZ, OHIO SCIENTIFIC,
CROMEMCO, PROCESSOR TECHNOLOGY, RAIR BLACK BOX,
DYNABYTE, SD SYSTEMS, RESEARCH MACHINES, ALTAIR,
EXIDY SORCERER, IMSAI, HEATH, and 8” IBM formats

Software Software
with J Manual with f/f Manual
SOFTWARE SYSTEMS Manual / Alone Manual / Alone

O) CBASIC-2 Disk Extended BASIC — Non-interactive BASIC © DISTEL — Disk based disassembler to intel 8080 or TOL

with psevceed compiler and runtime interpreter. Supports
full file control. chaining. integer and extended precision var-
iables etc. £75/£10

STRUCTURED SYSTEMS GROUP

QSORT —. Fast sort/merge program for files with fixed record
length, variable field length information. Up to five ascending or
descending keys. Full back-up of input files created. Parameter
tile created, optionally with interactive program which requires
CBASIC. Parameter file may be generated with CP/M assem-
bler utility .£50/£12

GRAHAM-DORIAN SOFTWARE SYSTEMS

APARTMENT MANAGEMENT SYSTEM -- Financial
management system for receipts and security deposits of
apartment projects. Captures data on vacancies. revenues,
etc. for annual trend analysis. Daily report shows late rents.
vacancy notices. vacancies. income lost through vacancies.
etc. Requires CBASIC. Supplied in source code, . £300/£25

INVENTORY SYSTEM — Captures stock levels. costs.
sources, sales, ages. turnover. markup. etc. Transaction in-
formation may be entered for reporting by salesman. type of
sale. date of sale. etc. Reports available both for accounting
and decision making. Requires CBASIC. Supplied in source
code. £300/£25

CASH REGISTER — Maintains tiles on daily sales. Files
data by sales person and item. Tracks sales. overrings. re-
funds. payouts and total net deposits. Requires CBASIC
Suppled in source code .£300/£25

MICRO FOCUS

CIS COBOL — Version 3 is ANSI! 74 subset with extensions
which offer powertul interactive screen formatting and built in
cursor control. Version 4 additionally offers full level 1 ANSI for
Nucleus. Table Handling. Sequential Relative and indexed | O
inter-Program Communication and Library
Version 3, £295/£25
Version 4. £395/£25

FORMS — interactive utility to create CIS COBOL source
code to perform CRT screen handling in applicawon programs.
Supports ‘full prompt text. protected fields and input validation

against data type and range expected £65/£10
When purchased with CIS COBOL £55/£10
OTHER

tiny C — interactive interpretive system for teaching struc-
tured programming techniques. Manual includes full source
listings £45/£30

C Compiler — Supports most major features of language. in-
cluding Structures. Arrays. Pointers. recursive tunction evalu

ation. linkable ‘with library to 8080 binary output. Lacks data
initialization. long & float type and static & register class speci-
fiers. Documentation includes “C” Programming Language
book by Kernighan & Ritchie £65/£10

(] ALGOL 60 Compiler - Powertul block-structured language

featuring economical run time dynamic allocation of memory. Very

Ny} compact (24K total RAM) system implementing almost all Aigol 60

teport features plus many powerful extensions including string
handling direct disk address I/O etc. Requires Z80
CPU.. * ,€110/£12

C) Z80 Development Package — Consists of: (1) disk file

line editor. with global inter and intra-line facilities: (2) Z80
relocating assembler. Zilog/Mostek mnemonics. conditional
assembly and cross reference table capabilities: (3) linking
loader producing absolute Intel hex dsk file for CP’‘M LOAD
DDT or SID facilities. .£50/£12

(_] 280 oer eee Mace, break and examine registers with
standard Zilog/Mostek mnemonic disassembly displays. Facilities

Xitan Z80 source code. listing and cross reference files. Intel or
TDL Xitan pseudo ops optional. Runs on 8080. Standard CP'M
and TRS-80 CP/M versions available €35/£7

DISILOG — TEL to Zilog:Mostek mnemonic files.
Runs on Z80 only. £35/£7

TEXTWRITER Il — Text formatter to justify and paginate
letters and other documents. Special features include insertion
of text during execution from other disk files or console, permit-
ting recipe documents to be created from linked fragments on
other files. Ideal for contracts. manuals. etc. €45/£3

WHATSIT? — interactive data-base system using associa-
tive tags to retrieve information by subject. Hashing and ran-
dom access used for fast response. Requires CBASIC

£70/£15

XYBASIC interactive Process Control! BASIC — Full disk
BASIC features plus uniaue commands to handle bytes. rotate
and shift, and to test and set bits. Available in Integer, Ex-
tended and ROMabile versions.

Integer Disk or Integer ROMabie £165/£15
Extended Disk or Extended ROMable £215/£15

SMAL/80 Structured Macro Assembled Language — Pack-
age of powerful general purpose text macro processor and
SMAL structured language compiler. SMAL is an assembler
language with iF-THEN-ELSE, LOOP-REPEAT-WHILE, DO-
END. BEGIN-END constructs £40/£10

Selector Ii — Data Base Processor to create and maintain
single Key data bases. Prints formatted. sorted reports with
numerical summaries. Available for Microsoft and CBASIC
(state which). Supplied in source code £105/£12

Selector Ill — Multi (.e.. up to 24) Key version of Selector 4!
Comes with applications programs including Sales Activity. In-
ventory. Payables. Receivables. Check Register. Expenses.
Appointments. and Client Patient. Requires CBASIC Suppled
in source code £155/£12
Enhanced version for CBASIC-2 £185/£12

CPM/374X Utility Package — has full range of functions
to create or re-name an IBM 3741 volume. display directory
information and edit the data set contents. Provides full file
transfer facilities between 3741 volume data sets and CP/M
files £125/£7

Flippy Disk Kit — Template and instructions to modily sin-
gle sided 5%” diskettes for use of second side in singled sided
drives £6

Orders must specity disk
type and format.e g North
Star Honzon single density.

Add VAT to orders for solt-
ware (not manuals alone)
Add 50p per item postage
and packing (minimum £1)

All orders must be prepaid
fexcept COD or credit
card) Make cheques POs
efc. payable fo Lifeboat
Associates

Manual costs are deduct
able from subsequent soft-
ware purchase

The sale of each pro
prietory software package
conveys a license for use
an one system only,

on similar to DDT. £20 when ordered with Z80 Development
w Package... Ane : -£30/£7

Lifeboat Associates, 32 Neal Street.London WC2H 9PS. 01-379 7931 ™ The Software Supermarket is a trademark of Litaboat Associates

¢ Circle No. 104
PRACTICAL COMPUTING January 1980 7

ee ee

PET
Pet 2001
From £515

NEW PET 2001 with large keyboard.
From £645.00

2 commodore
Author sed Dealers

PET 2001-16N (16K RAM and New Large Keyboard)* £645.00
PET 2001-32N (32K RAM and New Large Keyboard)* £795.00
PET 2001-8 (Standard PET with 8K memory) £515.00
CBM 3040 (Dual Drive mini-floppy 343K User Storage)% £795.00
CBM 3022 (80 col. Printer :— PET graphics—tractor feed)x £645.00
IEEE/RS232 Serial Interface ‘A’ Output only £106.00
1{EEE/RS232 Serial Interface ‘B’ Input/output £186.00
{EEE-488/Centronics type paratlel Interface £45.00
PET C2N External Cassette Deck £53.00
Interface to $100 (4 slot motherboard) £112.00
(EEE to Pet Cable /IEEE to IEEE Cable (Resp. Foe

COMPUTHINK dual drive up-to 800K ee from
4 inc.

% Educational discount 5% on
ren

items indicated.
Sorceror j
Now with the
$100 Bus Expansion
Interface and Dual Dealers
Drive mini-floppy Disk
Sorceror 16K RAM (inc. UHF Modulator) —- £740.00
Sorceror 32K RAM (including UHF Modulator) £840.00
Exidy Video Monitor (High Resolution) £240.00
Exidy Dual Drive mini-floppy Disk (630K storage) £1195.00
Exidy $100 Bus with interface+Motherboard+ PSU £200.00
Exidy Mini-floppy Disk Drive (143K Storage) £495.00
CP/M for Sorceror on Disk £145.00

Computer with PALSOFT in ROM (16K RAM) B/W
Computer with PALSOFT in ROM (16K RAM) Colour
Apple mini-floppy Drive (116K storage) inc. Controller
Parallel Printer Interface Card

High Speed Serial (RS232C) Card

RAM Upgrade (16-32K, 3248K)
ITT 2020 & EUROAPPLE Authorised Dealers

Advanced Systems
Altair, Equinox, Billings, Heath, Rair, Horizon.
Installations to include hard disk, and multi tasking

Terminals (most Brands)
Pentland V1, 80 char./24 lines 2 page memory

£750
£819
£398
£110.00
£110.00
£69

£580

Ansaback ‘Phonemate’ Telephone Answering Machine, voice
operated twin cassette £190.00

Software
Personal
Petsoft COMPUSETTES Software @ censor

Lifeboat Associates (Authorised Dealerships, Send for Catalogues)
PILOT (for TRS 80) text orientated language £18.00
COMAC I11 Suite- Computerised Accounting for TRS 80 £75
STOCK CONTROL (TRS 80) tnventory, P/O & Invoicing £125.00
CP/M for TRS 80 £95.00
CBASIC for TRS 80 & Sorceror £75.00
FORTRAN for TRS 80 £85.00
Estate/Employment Agency Systems, Fortran 80, Cobol 80, Pascal
Etc. Diskettes 5% (blank) boxed (min. order 10) each from £3.00
C12 Cassettes (Min. order 10) each £0.45
Computalker Speech Synthesis for $100 £350.00
Books — Large range of Microcomputer related books & magazines.

If you don’t see it — ask if we have it.

T & V JOHNSON (MICROCOMPUTERS ETC) LTD.

Member of the TV Johnson Group of Companies

165 London Road, Camberley, Surrey GU15 3JS

48 Gloucester Road, Bristol BS7 8BH

148 Cowley Road, Oxford OX4 1JJ.

Branches at: Birmingham, Bristol, Edinburgh, Leeds, London, Louth,
Newmarket, Nottingham, Oxford, Byfleet, Wokingham.

For Hardware, Software, Peripherals .Consultancy and Competitive Prices.

MICROCOMPUTERS ETC

CAMBERLEY

(0276)

)62506
(0272) 422061
(oses) 721461

TRS 80
MODEL II

with up to64 K RAM
and 2:0MB

Disk Storage!

TRS 80, 4K Level 1 (Keyboard with 4K memory+
VDU+Cassette drivet+240v PSU)

TRS 80, 4K Level || {as above but with Level I! basic)

TRS 80, 16K Level II (as above but with 16K memory)

TRS 80, Expansion Interface with 16K RAM

TRS 80, Expansion Interface with 32K RAM

Shugart Mini-floppy Disk Drive {including PSU)

Micropolis Mini-floppy Disk Drive (including PSU)

Percom FD200 Mini-floppy Disk Drive (inc. PSU) 110v.

Micropolis Dual Drive (394K) (including PSU)

TVJ 232T Serial Interface for TRS 80

TRS 80 Screen Printer {text+graphics) (110W)

Centronics Parallel Printer interface for TRS 80

TRS 80 Voice Synthesizer

TRS 80 Numeric Key Pad supplied & fitted

New Radio Shack Micro Printer

Radio Shack Phone Modem

NEWDOS Super-enhanced TRSDOS

Levelt II Super-enhanced BASIC

RSM Assemble/Monitor on Disk

MICROCHESS or SARGON CHESS Cassette/Disk

UHF Modulators (encased with jeads for 625 lines)

RAM upgrade (4-16K, 16-32K, 3248K) supplied and fitted
at our premises (Kit £80) £85.00

‘Electric Pencil’ text/word processing package {on cassette) £65.00

‘Electric Pencil’ text/word processing package (disk version) £109.00

‘Electric Pencil’ keyboard mod. to give lower
case with text/word processing package. £28.00

$100 interface for TRS 80 (6 slots) £375.00

‘Library 100’ — 100 progs for TRS 80 on cassette (Level 1) £39.00

£365.00
£425.00
£499.00
£275.00
£360.00
£315.00
£315.00
£299.00
£995.00
£35.00
£445.00
£45.00
£345.00
£69.00
£245.00
£160.00
£49.00
£34.00
£19.95
£14.00
£20.00

NOW AVAILABLE

Compucolor II

Computer with colour Monitor,

Keyboard and Integral Disk Drive
From only £1058.00

Second Disk Drive £316.00

2 ees

Programmed Diskette albums available from

Printers

Teletype 43 KSR Serial Printer
Teletype 33 KSR Serial (110 Baud) Reconditioned
Centronics 779 parallel printer (tractor feed)
Anadex DP 8000 serial/parallel printer

(112c.ps. bi-directional tractor feed)
Centronics Micro printer (20, 40, 80 columns selectable)
Black Box Printer (80 col.) special offer £299
HEATH WH 14 serial (80, 96, 132 cols. selectable) £510.00
MICROHUSH (40 cps. bi-directional, thermal) + interface £266.00
QUME SPRINTS daisy wheel serial printer P.O.A,
PRICES EXCLUDE VAT. FREIGHT & HANDLING SEND OR
‘PHONE FOR PRICE LIST & BROCHURES
{All prices correct at time of compilation)
Directors: Or. R.V. King, BA, MIEE

S.G. Johnson, BSc. (Hons.)

T.S. Johnson, ABIBA, ACMB, F BSC, MBIM
A.S. Barton, ACII, ABIBA, CaipAF

(0276) 62506
9272) 422061

(0272)

(0865) 121461 Telex 858893

Hours of business 9.30—5.30 Mon-Fri. 9.30—1.00 Sat.

£825.00
£550.00
£825.00

£560.00
£395.00

+ Ansaback eves
and w/ends.

PRACTICAL COMPUTING January 1980

Everything you always wanted
to plug into your PET,
wie APPLE or TRS-80* ie

DOUBLE DENSITY DISK STORAGE
FOR THE TRS-80
(220% capacity of Radio Shack’s)
TRS-80 owners can now increase their on-line mass storage 3D Graphics — High resolution plotting in 3D! ... £30.00
capacity. How? By using the 77 track Micropolis model LISP — programming language suitable for research in
1033-11 dual drives. artificial intelligence (Disk)
Cost: only £995.00 for two drives, to give 394K on-line. DATA MANAGEMENT/REPORT GENERATOR - easily
How do |! use it? TVJ Microcomputers Etc.- provides you formats disk files, allows entry, edit, delete & list of
with a special program to let your TRS-80 DOS know there records; and retrieves data for display or calculation on
are extra tracks. This program was written especially screen or printer £200.
by Randy Cook, author of TRS-80 DOS. ELECTRIC PENCIL — powerful word processor allows full

RADIO SHACK VOICE SYNTHESIZER for TRS 80 CUrsor movement, insert/delete, string search, block move-
provides the ability to speak in English and limited foreign ment, adjustable line length, justification (on cassette) .£65.

: -..) LOWER CASE MOD KIT FOR ABOVE
languages. Capable of producing 62 phonemes (sound units)
that are the building blocks of spoken language. Includes DISK BASED WORD PROCESSING PACKAGE. £115.00.

: ie RSM-2D DISK MONITOR — powerful system manipulates
audio amplifier and speaker £3455 a 5 ;
S “ Ph a disk data, has Z-80 breakpoint routine £25
VOXBOX Voice recognition — TRS80 cm now respond ISAM — Index Sequential Access Method — Subroutines
TRS 80 PRINTER INTERFACE CABLE ~ allows you ‘we to facilitate control of RANDOM DATA Files (Disk). .£45.
connect a parallel printer (e.g. Centronics 700 series) directly PASCAL for TRS 80 now available! (Disk) ;
to your Level I! Keyboard, i.e. Expansion interface not 9! 800 Gommunications Software for TRS80 (Disk) £60
LeGuifed , SARGON CHESS — 16K Iv Il — the 1978 champ... . £14
“MICROCHESS 1.5 by Jennings — 4K any lev
TRS 80 NUMERIC KEYPAD MOD :
RADIO SHACK aeerinr en for Taesomt0 Cotumige ee ae ee ment of 100 progiait for... £39
2%"' electro-static Printer, switch selectable RS232 Cen. FORTRAN My THE peed 8 cot Companies
tronics Parallel and TRS 80 BUS Interfaces £945, ipabimbeall hes ALLL CROS 5 Meck
“speed up those computation-bound programs. Complete
Package includes compiler, .relocatable assembler, text
editor, and linkingloader................... £85.

MICROHUSH Printers for TRS 80, PET or APPLE. 40 cps,
40 column Thermal Printer (inc. Interface) £266.

APPLE __ CP/M + CBASIC for THSGO............ cau £170)
SPEECHLAB — provides voice control for the Apple. Train ae DOS — TASoOS dalicorrections & enhancetfientsfes

your Apple to understand and act upon the spoken word

linc, microphone) £165.00 NEW DOS + —As above but with further facilities:- KBF IX,

4 i -.. RENUM, Screen to Printer one step, DOS commands from
fe ae atiiecolvolmple sec, Gopaae wey OO BASIC, Level | in Il, SUPERZAP, Disassembler, Open ‘E’
GRAPHICS LIGHT PEN £165.00t0 end of sequential file, Load and Save faster, List

PASCAL CARD — Powerful new language for the Business Variables... 0... 2... vee + £49.
User with PASCAL, PALSOFT & INTEGER basic. . .£296. PET

COMMUNICATIONS CARD, allows APPLE to exchange JOYSTICK PACKAGE — complete with connector, soft-
data with a remote computer over ordinary telephone lines ware instructiond

through a modem £132.00.Programmers Toolkit — Plug-in ROM to provide additional
AC line controller — allows APPLE to monitor and control facilities for 8K and 16/32K PETS (msp) £75/£55.
AC devices remotely £270.00 MICROCHESS 2.0 by Jennings . .

EASY WRITER — Word Processing System (Disk). £85.00.74 COMMON BASIC PROGRAMS on 1 tape

A2FP Function Plotter — Comprehensive Graph PlottingPETACT BUSINESS SYSTEMS
£18.00.CBM DISK-BASED BUSINESS SOFTWARE

Plotting Facility in High Resolution (Disk) £18.00, Commodore Word Processor — powerful word processor
PILOT — Programming Language suitable for Educationalsystem

Applicants £35.00.CSTOCK — Stock Control — gives complete Stock Report
U — Draw II — High Resolution Graphics Editors Create : J.0'
a figure then rotate, expand contract etc and store inCBIS — Business Information System — Storage & Retrieval
Disk £27.50. of all types of company records

Programmer’s Aid HI — Plug in ROM gives numerous (We are authorised CBM Business Software Dealers)
facilities inc. Renumber, Mrge, High Res in Integer Pas

T & V JOHNSON (MICROCOMPUTERS ETC) LTD.
Member of the TV Johnson Group of Companies
165 London Road, Camberley, Surrey GU15 3JS

48 Gloucester Road, Bristol BS7 8BH

Branches at: Birmingham, Bristol, Edinburgh, Leeds, London, Louth,
Newmarket, Nottingham, Oxford, Byfleet, Wokingham.

® Circle No. 105
PRACTICAL COMPUTING January 1980 9

aculab...

HIGH-QUALITY PRINTOUT FOR
YOUR WORD-PROCESSING SYSTEM

The ACULAB 735P, a fully self-contained interface
for IBM golfball output typewriters and printers.
Parallel model accepts 7-bit ASCI! data via a
Centronics compatible connector.

Serial model accepts RS232/V24, selectable Baud
rates. Parallel model may be retro-fitted with serial
board.

Programmed for 7 different typehead layouts, covers
all common golfballs and an ASCII ball, switch
selectable from the front panel.

STOP/GO switch, ONLINE/OFFLINE switch, also
online/offline under software control.

PARA EIR: .citiee. cee Aes. £155-00 + VAT
SETIall wvewade, 1m ok deaeerenvosren © an £205-00 + VAT

Accessories and cables available for use with PET/
SORCERER/TRS-80 (with or without expansion
interface) APPLE/ITT/RML380Z etc., etc.

Wiring and testing service for typewriters and
printers.

Typewriters and printers available wired and tested
and ready to go.

24 Heath Road,
Leighton Buzzard, Beds.
LU7 8AB

Trade enquiries welcome.

Ltd. For further information
Telephone. 0525-371393.

SCIENCE
FACT

The invention of the silicon chip by Texas Instruments, turned
science fiction into science fact overnight. That was in 1965, but
only now is the full potential of the ‘chip’ being realised.

Texas Instruments offer you 14 years of extensive research
and development in the form of data and reference books that
will enable you to get the very best from their micro-miracle.

Whether it’s your business or hobby, anyone interested in
micro-technology will find these books invaluable.

Get the real facts from the inventors of the ‘chip: °

TEXAS INSTRUMENTS

Texas Instruments Ltd, Supply Division,
MS21, Manton Lane, Bedford Tel: 0234 67466

Slough: 186 High Street, Slough, Berks. Tel: 0753 70531

Manchester: Knightsbridge Mall, Arndale Centre,
Market Street, Manchester. Tel: 061-832 6238

SUPPORT MEMBERS OF THE
COMPUTER RETAILERS
ASSOCIATION...

THEY WILL SUPPORT YOU.

For further details on the associations aims,
membership, code of conduct etc.

Please contact: Ms. Heather Hodgson,
47, Creswell Road, Newbury, Berkshire.
Tel. (0635) 42486

Please send me the books ticked. | enclose £ plus £1.15 P&P

DATA BOOKS

OTTI.L. Data £5.00 D Linear Control Data £2.50
0 Interface Circuits Data £3.50 © Optoelectronics Data £3.50
OD Power Semiconductor Data £3.20

O Transistor and Diode Vol. | £3.50

OTHER T.I. BOOKS
D Optoelectronics Theory and Practice £7.50
D Semiconductor Circuit Design Vols. | to |\V £6.50 each
0 Volume V £7.95
0 Understanding Solid State Electronics £1.20
Understanding Digita! Electronics £3.50
Software Design for Microprocessors £12.00
9900 Assembly Language Guide £4.00
9900 Family Systems Design £8.00
Calculating Better Decisions (SR51-I!) £5.00
Calculator Decision Making Source Book (TI-51 Il) £5.00
Calculator Analysis for Business and Finance (T!-42 MBA) £7.00
D Sourcebook for Programmable Calculators (T!-58/58C/59) £11.45

Ti-59 PAKETTES

Each pakette contains complete listings of programmes suitable
for use with the Tl Programmable 59 calculator £5.95 each

D Electronic Engineering -] Oil/Gas/Energy

O Black Body Radiation D Printer Utility

jajale)ololelal

0 Astrology © Programming Aids
(] Marketing/Sales O Fluid Dynamics
O Mathematics 0 3D Graphics

0 Production Planning
O TI-59 Fun (Games Pakette)

D Lab Chemistry

NAME

ADDRESS ——

PC/1/80

® Circle No. 108
PRACTICAL COMPUTING January 1980

nascom

PLAIN
PAPER
PRINTER

BOXED AND BUILT
FOR ONLY £325:::

FEATURES PRetswaese eo

§ TO NASCOM MICROCOMPUTERS LTD |
@ Serial RS232 interface @ Automatic CR/LF | 92 BROAD STREET |
@ 80 characters wide @ 83" paper CHESHAM |
@ Bidirectional printing @ Optional tractor feed iu BUCKS i
@60 lines per minute @Baudratefrom110to9600 Tel: 02405 75155 | Nascom Microcomputers
@10 line print buffer @External signal for optional §f ; fl
@96 character ASCII set synchronisation ofbaudrate § OS lomanrie ; 3 ees ee
(includes upper/lower . =i. NM/PC/3 §
case, $#E£ § wave a
|
eos - ADDRESS i
The Nascom IMP plugs straight into a Nascom 1/2 but is
usable with all other micro systems. Parallel option will be | J
available shortly. | -
| ;
5 |
§ Access) |
Bore oe 5

eto tt td er fe
® Circle No. 109

PRACTICAL COMPUTING January 1980 11

Video Vector Dynamics Ltd

WE SELL SOLUTIONS. Have you discovered that your

problems really begin after you've bought the hardware? Either you’ve bought
the wrong hardware or no software exists to make it work properly. We
specialise in providing total solutions to problems and professional after-sales
support of hardware and software. We have the resources sucessfully to
implement commercial, scientific and instrumentation/control projects.

COM M E RCIAL. Typical of our recent projects in this area was the

connection of 12 remote stations to a central unit. This was achieved by using
Commodore Pets as the remote stations allowing a degree of local processing
linked via modems to a central $100 microcomputer with substantial disk
storage capacity. This type of configuration is ideal where a timlted amount of
local accounting is required at each site but with a central collation of inform-
ation on stock, payroll, etc.

SCIENTIFIC. Our scientific packages are currently in use by a number
of major multi-national companies. Typical of these packages is our Chemical
Graphics System used by pharmaceuticat companies in drug design. This is
designed to run on PDP-11 configuration but a subset of the facilities is
available on microcomputers.

INSTRUMENTATION/CONTROL. We can supply a

complete range of hardware and software packages covering analog, digital
and graphical input/output and logging using fast microprocessor-based
systems.

COST. Due to our famillarity with a wide range of hardware we can supply
systems either optimised for minimum price or maximum performance — you
decide on the price/performance mix.

In addition to consultancy and turnkey packages we offer the following
proprietary products:

FASTLI B. This package is based on the AMD9511 arithmetic chip and is
a complete hardware/software system. Use of FASTLIB is completely trans-
parent to the user of Microsoft FORTRAN and BASIC. The software fs totally
integrated with the FORTRAN/BASIC compiler and slmply by replacing the
Microsoft-supplied library by FASTLIB existing programs can run 5 — 20 times
faster without any modification. The hardware requires a single $100 slot. In
addition to enhancing the speed of execution of the existing FORTRAN/ BASIC
functions and operations, additional functions have been implemented -
NINT, TAN, ASIN, ACOS, SINH, COSH, THAN & RAN (a pseudo-random
number generator).

GLI B. A graphics library enabling complex pictures to be produced from a
series of simple subroutine calls such as : VECTOR (draws a line between any
two (x,y) points); CIRCLE (draws a circle of any radius centred on any (x,y)
point); TEXT (plots a 64-character ASCII set); STEXT (plots Greek and Mathe~
matical symbols}; etc. Plots can be saved on or retrieved from disk by single
subroutine calls. The standard package uses the Vector Graphic High-
Resolution Graphics board but the software can be configured for any graphics
board or device. Microsoft FORTRAN, MACRO or BASIC Is also required.

GRAPH. Fits elther an arbitrary polynomial or a cubic spline to a set of
{x,y} points. The spline routine is for drawing (smooth) curves through a series
of points while polynomial finds the analytical form of the function corres-
ponding to the (x,y) points.

SFGC. This is a communications program which enables connection of
any two computers over a serial line (modem or dedicated). This has been
used, for example, to link a microcomputer running CP/M to a PDP-11/
LSI-11 running RT-11/RSX-11M and a PDOP-11/LSI-11 to an (BM 370, DEC —10
etc. mainframe.

39 Hope St., Glasgow G1.

041-339-6782

MHI HCHRHO]
CHOWN AT ROHL

— THE INTERFACE EXPERTS

224 EDGWARE ROAD
LONDON w2
Tel 01-402 8842

MICRO CONTROL have been building specialised hardware and writing
software, since Apple first came into the country. We can interface your
Apple to anything with a custom designed card for a reasonable price.
We can also provide Business Systems for Apple II and Micro Star to your
requirements.

Centronics Printer Card £132.00
Apple disk drive £355.00

with controller crd £398.00
Micro Hush Printer

+ Apple Interface £266.00
Thermal paperoll for Micro Hush £2.00

4-Channel A/D cards 12-bit £174.00; 8-bit £116.00
4-Channel D/A 12-bit £149.00; 8-bit £110.00

16K Add In 150ns £58.00

Apple Il 16K £810.00

High Speed Serial Card £110.00.

Com. Card £140.00

10in b/w monitor £132.00 =‘ Integer Firmware Card (inc. Mini-Assembler)
12in b/w monitor £210.00 £110.00

Apple Pascal £289.00 Symtec light pen (for Apple) £165.00.
MicroStar £4,950.00 Apple Voice recognition Card £165.00.
Printers VDU’s ITT Apples Software & one- Micro Products Eprom burner £140.00.

off’s P.O.A. Box of 10 diskettes £30.00.

Colour board for Apple. Have your text in colour! Clean Lo-res/Hi-Res hires colours £147.00
Micro Con. Real Time Clock. Date/Hr/ Minute £90.00

8-Channel Mains Controller £140.00

4-Channel Mains Dimmer £175.00

COMING SHORTLY:— Colour for PET and TRS 80

8-11 Cambridgé House
Cambridge Road,

ENTERPRISES a

TEL: 01-591 6511

EUROPE’S LARGEST SELECTION OF MICROCOMPUTER BOOKS, MAGAZINES AND SOFTWARE rOR THE HOBBYIST, EDUCATIONALIST

PROFESSIONAL AND RETAILER

SUMMER HOLIDAY BONUS. for the purchase of 3 books or more,
and paying by cheque, P.O. or cash, give yourself a 10% DISCOUNT!

Introduction to Microcomputers: by Osborne
Vol 0: Beginners Book

Vol 1: Basic Concepts

Vol 2: Some Real Microprocessors (without binder}
Vol 2: Some Real Microprocessors {with binder)
Voi 3: Some Real Support Devices (without binder)
Vol 3: Some Real Support Devices {with binder
Updating subscription (6 issues) for Vol 2
Updating subscription (6 issues( for Vol 3
Updating subscriptions for Vol 2 & 3

1 Updating issue Ispecify for Vol 2 or 3)

1 Binder (Specify for Vol 2 or 3)

6800 Programming for Logic Design
8080 Programming for Logic Design
280 Programming for Logic Design

More BASIC Computer Games (coming soon)
BASIC Computer Games (also see software section)
What To Go After You Hit Retarts

8080 Galaxy Game

SUPER-WUMPUS =A game in 6800 Assembler code & BAS!C

Computer Music

Computer Rage IA Board Game)

Artist and Computer

Games with a Pocket Calculator

Games, Tricks & Puzzles for a Hand Calculator

Introduction to TRS-80 graphics
Take My Computer Please... (light hearted fiction)

280 Instruction Handbook

8080 Programmers Pocket Guide
8080 Hex Code Card

8080 Octal Code Card

Best of BYTE

Scelbi BYTE Primer

Best of Creative Computing Vo! 1

Best of Creative Computing Vol 2

Best of MICRO (Issues 1-6 of Micro Magazine)

280 Assembly Language Programming (coming soon)
6502 Assembly Language Programming (coming soon)
Microcemputer Programming 6502

6502 Applications Book {coming soon}

8080A 8085 Assembly Language Programming

6800 Assembly Language Programming

8080 Software Gourmet Guide and Cookbook

6800 Software Gourmet Guide and Cookbook

8080 8085 Software Design

6800 Tracer An aid to 6800 Programme Debugging
Program Design

Programming Techniques: Simulation

PiMS A Database Mariagement System
Scelbal High Level Language * Supplements
Basex A Simple Language + Compiler fur the 8080

MAGAZINES

Magazine Subscriptions:

Subscriptions start within 3 weeks
MICRO 6502 Jourtit 112 issuest

Pei sonal Computing (12 issues)
interface Age {12 issues!

Dr Dobbs Journal {10 issues)
Computer Music Journal (4 isstias)
People’s Computers I6 issues)
BYTE (12 sssues)

Creative Con:puting (12 issues)
Kilobaud (12 issues)

HOW TO ORDER

Please note our book magazine prices include postage and
packing, but not insurance, if wanted add 12p for every £10

of books ordered. Make cheques, PO’s etc. payable to: -

L.P. Enterprises.

CREDIT CARDS accepted

BARCLAYCARD VISA/ACCESS/ DINERS CLUB/

AMERICAN EXPRESS

Phone: 01-553 1001 for Credit Card orders (24 hr answering service)
All publications are published in U.S.A. and shipped into

Britain air-freight by LP. Enterprises. In unusual cases,
processing may exceed 30 days.

Prices subject to change without notice

TRADE ENQUIRIES WELCOME

PRACTICAL COMPUTING January 1980

Microprocessors from Chips to Systems
Microprocessor Interfacing Techniques
280 Microcomputer Handbook

TV Typewriter Cookbook

Cheap Video Cookbook

CMOS Cookbook

IC OF AMP Cookbook

RTL Cookbook

TTL Cookhook

IC Timer Cookbook

Ciarcias Circuit Cellar

First Book of KIM

Introduction to Personal and Business Computing

Getting Involved with your Own Computer

Buyer's Guide to Microsoftware

How to Profit from Your Personal Computer

Microcomputer Potpourri

Hobby Curnputers are Here

New Hobby Comrguters

Understanding Microcomputers and Small Computer Systems

Instant BASIC

Basic BASIC

Advanced BASIC

My Computer Likes Me Wher) | Speak in BASIC
Calculating with BASIC

Users Guide to North Star BASIC

Introduction to PASCAL

Accounts Payable and Accounts Receivable
Payroll with Cost Accounting
General Ledger

Basic Software Library:

Vol 1: Business and Games Programs

Vol 2: Maths. Engineering and Statistical Programs
Vol 3: Advanced Business Programs

Vot 4: Generat Purpose Programs

Vol 5: Experimenters Programs

Vol 6: Miniature Business System

Vol 7: Chess/Medbil/Wdproc Programs

Some Common BASIC Programs
Computer Programs that Work {in BASIC)

32 BASIC Programs for the PET

8080 Standard Monitor

8080 Standard Editor

8080 Standard Assembler

Special Package: 8080 Assembler, Editor, Monitor
Bar Code Loader for 6800, 8080. ZB0 and 6502
Tiny Assembler for 6800 Systems

RA 6800 ML An M600 Relocatable Macro Assembler
LINK 68 — An M6800 Linking Loader
MONDEB ~— An advanced M6800 Monitor Debugger

Overseas Magazine Back Issues
Price Micro 6502 Journal
Personal Computing
£12.50 Interface Age
£17.00 ROM
£25.00 Dr Dobbs Journal
£13 50 Computer Music Journal
£11.00 Peopie’s Computers
£8.50 BYTE
£24.50 Creative Computing
£16.50 Calculators and Computers
£21.00 Kilobaud (reprints only)
73
Magazine Storage Box (Holds 12)

THIS LIST CANCELS ALL PREVIOUS PRICE LISTS: EFFECTIVE JULY 1979
DUE TO FLUCTUATIONS OF THE DOLLAR. PRICES SUBJECT TO CHANGE WITHOUT NOTICE.

Send to address on page All Otders must be Prepaid:

Indicate Payment Method; and underline items required. Total Enclosed £

My cheque, P.O., 1.M.O. is enclosed in Sterling on U.K. Bank
Charge to Barclaycard/Visa/ Access/Diners/ American Express

Credit Card No. . Expiry Date.
Name
Address .

. POSTCODE
Signature

T.W. COMPUTERS LTD.

— for ITT 2020 Apple Microcomputers
in the Northwest

We can supply you with just a machine, ora
system taylored for your needs.
MICROCOMPUTERS FROM £750 + VAT.
DISC SYSTEMS FROM £395 + VAT
PRINTERS FROM £510 + VAT

PAY CLERK

— at last, a simple PAYE and WAGES |!

programme!

@ PAYE and N.|. tables made redundant
® Calculates PAYE, N.I. and NET PAY
@ Full details for wage book.

Only £145 + VAT.

In preparation, PAYMASTER prints wages books
and stores all PAYE information during the year.

T.W. COMPUTERS LTD. 293 London Road,
Hazel Grove, Stockport, Cheshire.
Tel. 061-456 8187.

e Circle No. 113

WE HAVE ALL THE PIECES!

COME TO CAMBRIDGE AND SEE THE SOLUTION

We can demonstrate practical business systems,
with proven software, for many applications.

Leasing, installation and training available.

PROTECHNIC COMPUTERS LID.

264 Newmarket Road, Cambridge.
0223 -314855
¢ Circle No. 114

Software Engineer

c. £8,000 p.a.

The Computer Aided Test Department
of a large electronics company West of
London, requires an engineer to study
and make recommendations relating to
the use of microprocessors in Automatic
Equipment technology.

You should have experience with
Automatic Test Equipment and a wide
range of microprocessors using high level
computer language such as ATLAS.

A knowledge of PASCAL would be an
advantage. Aged between 30
and 45 you should be able to
work on your own initiative as
well as having a degree level

OXON
AOLPHIN

&KERB

qualification. Brief visits abroad may be
necessary, and a European language
would be an advantage.

Asalary of around £8,000 p.a. will be
negotiated and other benefits include
generous relocation assistance where
appropriate.

Please write with full details, to
R. J. Wareham, Moxon Dolphin and Kerby
Ltd., 60 St. Martin's Lane, London
WC2N 4JB quoting ref: RW/643/PC.
Please list in a covering letter any
companies to whom you do not

wish your application to
be sent.

LTD
MANAGEMENT SELECTION

PRACTICAL COMPUTING January 1980

-43— comart sas.

| =

our factory. After allit’s got \

our name on it. hee
| The next time you want \
5

| We care about what leaves

reliable microcomputer }
products ~ single card |
| computers, floppy disk

| systems and disk systems —

SPECIALISTS

take alook at what we putin
| our boxes.

\
\ A Comart Computer Catalogue will
i

show you.

Write to |

<
(40) 43 comart | )
=

/ Comart Ltd., P.O. Box 2, St. Neots,
f Huntingdon, Cambs.
| Or telephone (0480) 21 5005. ' :

PRACTICAL COMPUTING January 1980

(8) FOR SCOTTISH READERS () Unleash your Pet* to its full capability.

TELETYPE 43 RANGE BICES Rep
KSR£800 :

complete 24
p chose . ne \

ANADEX

TELETYPE pp8000

M40 RANGE
10 of 30 c.p.s.
7 coal ALSO

ASR33

Two ways to 32K.
Add on or add in.

Silenced
£2750

80 col. dot matrix
~ Wide selection of
300 L.p.m, interfaces
112 c.ps.

oe ; £575

One way: Petite memory system The Other; Inpet memory board.
Self-contained peripheral for any @ Mounts onto Pet processor board.
Commodore Pet Built inPSU

MATRIX Plugs into mains and Pet. @ Simple to fit.
e
e

PRINTER No modifications required
No demands on Pet power supply.

No extra heat dissipation within Pet
cabinet.

No warranty problems.

Complete with all connectors,

ADM3A Low cost version
80 CHARACTERS
x 24 LINES

US) tearsiccien i=

* Attractive quantity discounts available Established
Scottish maintenance organisation since 1966

| te
KSL. KODE SERVICES LIMITED

CRAWFORD CHAMBERS, CALLENDAR ROAD,
FALKIRK. Tet: 22766 Telex: 449335,
e Circle No. 116 © Circle No. 117

Trademars at Commogore Business Systems

One way or the other you get a reliable memory from Plessey Microsystems,
Europe's leading memory manufacturer.Either way you get a memory to
make your Pet more like a powerful business computer.

Available from authorised distributors of Plessey Pet peripherals.

Send for tult information and the address of your nearest distributor.

PLESSEY
MICROSYSTEMS

Plessey Microsystems Limited, Water Lane, Towcester. Northants NN12 7JN
Telephone Towcester (0327) 50312 Telex 31628

YOU NEED MICROCOMPUTERS NOW!

Don't be left behind. In five years every progressive
business in the country will have computer facilities.
This will enable a reduction in their administration costs,
therefore lowering their unit cost price
plus being able to release administrative staff
for more cost effective work.

Micro Management will help you harness this new
technology and allow you to compete successfully in the
future. We can provide technical and accounting exper-
tise in a language you can understand

He who hesitates... .

MIGRIORMIAINEAIGIE MEN

13-15 CONNAUGHT AVENUE, FRINTON-ON-SEA
The Computer People Tel: Frinton 4592.

Considering a Microcomputer?

Be Sure to Check Out the Product Offerings of the World’s Largest

Full Line Microcomputer Company.

All Ohio Scientific machines come with microcomputing’s fastest full

feature BASIC-in-ROM or on-Disk for instant use.

Minimum Base

Challenger | Series Contiguration Price
Economical computer systems that talk in BASIC.
Ideal for hobbyists, students, education and the home.
Superboard ll -World’s first complete system ona board 4KRAM £ 188
including keyboard, video display, audio
cassette, BASIC-in-ROM and up to 8K RAM

Challenger IP —-Fully packaged Superboard Il with 4KRAM £ 238
power supply
Challenger IP Disk-Complete mini-floppy system 16K RAM £ 865
expandable to 32K RAM
Challenger lIP Series

Ultra high performance BUS oriented microcomputers for
personal, educational, research and small business use.
C2-4P -The professional portable 4KRAM &£ 404
C2-8P -The world’s most expandable personal machine 4KRAM £ 548
for business or research applications

C2-4P Disk -The ultimate portable 16K RAM £1050

C2-8P Single Disk -Ideal for education, advanced 16K RAM £1199
personal users, etc.

C2-8P Dual Disk -Most cost effective small 32KRAM £1790

business system

Challenger Ill The Ultimate in Small Computers

The unique three processor system for demanding business,
education, research and industrial development applications

C3-S1-World’s most popular 8” floppy based 32KRAM £2334
microcomputer dual floppys

C3-OEM -Single package high volume user version 32KRAM £2334
of C3-S1 dual floppys

C3A-Rack mounted multi-user business system 48K RAM £3403
directly expandable to C3-B dual floppys

C3-B -74 million byte Winchester disk based system. 48KRAM £8654
World's most powerful microcomputer dual floppys

C3 -29 million byte Winchester disk based system. 48KRAM £6320
dual floppys

Full Business and Data base Software

OS.AMCAP -A complete small business accounting package £ 656

including inventory, invoicing, A/R, A/P, CR, CD, general
ledger and P/L

OS.DMS -Data base Management System designed specifically ee AAS)
for small business information management.

-DMS based modules for Inventory/order, A/R & A/P, ES WTS
General Ledger, personnel/payroll, Query, Word each
Processing.
WP-2 -Complete word processing system with character ene

justification, global editing, paging, text justification,
proportional spacing and hyphenation.
~ALL PRICES ARE EX VAT.
OHIO SCIENTIFIC also offers you the broadest line of expansion accessories and
the largest selection of affordable software!

Compare the closest Ohio Scientific Model to any other unit you are
considering. Compare the performance, real expansion ability, software and
price, and you will see why we have become the world’s largest full line
microcomputer company.

WE ARE LOOKING FOR DEALERS THROUGHOUT EUROPE
PHONE MARK STRATHERN ON 01-981 3993

PRACTICAL COMPUTING January 1980

The
The Professional Portable
by Ono Screntific

Chie Seamntitic ow alters you Me wets ®

meal powertul poctabte parsons! compure oven ‘ote teenie
fr Beth BABIC th ROW and mint Huo

Comhqurations

Ca wd eemeng Feet

The
C2-8P

An exceptional value
in personal computing

——— SI C8 Cea Ret harars Che aa

The C3-B
nn

‘oan you teary Ciel:

Srawoano #FaMUNES

bg:

e Circle No. 119
7;

PROGRAMMABLE
CALCULATOR

CASIO FX 502

@ LINKS UP WITH AN ADAPTOR FOR PROGRAMME
DATA STORAGE ON STANDARD CASSETTES,
PLUS MUSIC SYNTHESIZING AND PLAY BACK
@ 256-step programme memory and 22 data ‘egislers
are beth protected (non-volatiei
@ Up to 10 levels of parenthesis nesting
@ True algebraic ‘ogic - easy key operations same as

whtten formulae

@ Battery service Ife is 1,300 hours Auto powe: att
feature 1s provided

@ Thin and bghiweight easy to carry around

@ Up to 10 programmes available programme keys
otherwise usable as user's functions

Apple 16K O
Disk with controller £375 O
Disk drive only £325
O
oR,

I
Pm arr
aoauese

@ 51 bulltan functions ali usable in programmes,

@A vanety of “jump” commands unconditional
jumps, conditional jumps and indirect .ump

®@ Up to 9 subrounnes incorporabie nesting possibe
up to 9 levets

@ Easy to edit and debug programmes PAUSE key,
random number key. back step/tapid run key

@ Amazing operating speed

16K add on memory £65
Please send brochure

Other information available on request

Optional FA-1 Programme Adaptor permits programme/data storage on standard cassette tape

recorders for re-entry. Typical storage/re-entry time 9-16 seconds, with a three digit code for
Svegh) CietRNS ls 6 ce 's wo Kis) Kies) ei wl i el ee) vie iete © 6 SW ie 8 els programme reference and identification. Also contains a music switch which converts both
calculators into musical synthesisers - duration of notes, rests, tampo, siur and tie are all

PRAGHOSS! fo 20c)sterciters oie eee hee GE ole « « Seratadae eines progremmabie.

MODEL FX-501P has an identical specification with the following exceptions; 128 steps (non-volatile)

CGMS Moshe oni Wd POMC EST tat I EM es OE CC cy programme memory capacity; 11 (non-volatile) data registers; up to 5 levels of parenthesis

nesting; up to 9 subroutines, nestable up to 4 jevels; up to 15 music notes (FX-502P up to 20)

EEE ae SE Dimensions of both are 96 mmH x 71 mm wx 141.2 mm D(H x 2)" W x 5 3” D) A comprehensive
Programme Manual, Instruction Booklet and leatheretie wallet are supptied FA-'comes complete witha
demonstration cassette with pre-recoded programmes, imctuding games and music

Please enclose cheque and send to
Business Computer Services
Pollards Farmhouse, Clanville,
Nr. Andover, Hampshire.
Telephone 0264 70 300

Allow 10 days for delivery
Allsystems delivered by SECURICOR
to Mainland U.K. —carriage free

ex ara @Ppic computar inc.

¢ Circle No. 120 © Circle No. 121

WE OFFER A COMPLETE SERVICE!

When you buy a computer from us — we don't give you the box and wave goodbye.

We realise this is a major purchase for a Company and take the time to find out your requirements, design
your computer system and write the software, or if you prefer to write your own, we will always be available to
advise you.

AVAILABLE BY MAIL ORDER AT LOWEST DISCOUNT PRICES
FX-501P (RRP £64.95) FX-502P (RRP £84.95) FA-1 (RRP £24.95)

£54.95 £74.95 £19.95

To sum up, Casio have produced an attractive and powerful instrument at a very keen
price which should eat up the market for calculators just below the ‘almost-a-micro
class. - Personai Computer World, October.

Prices include VAT at 15% and post and packing. Send your Company order, cheque of Postal Orders, or phone your
ACCESS or BARCLAY CARD number to

DEPT DL

THE BEAUMONT CENTRE
164-167 EAST ROAD
CAMBRIDGE C81 106

Tel: (0223) 312866

You can buy a wide range of fully-documented packages — Word Processing/Purchase & Sales Ledgers/
Stock Control/Incomplete Records/Medical Systems/Teaching Programs etc.

on Microcomputers such as—

APPLE II from £750 MICROSTAR trom ALPHA MICRO trom
(16K) £4,950 pelea a a
F Multi-user/Multi-task rom 1 to 32 terminals.

pS a ete — 1 gana 1.2/2.4 or 4.8 mb. From 10 mb. to 90 mb. disk
Printer £2,550 ; A complete system with 2 VDUs storage.

: & Printer £7,000 16-bit processor, Multi-user

operating system.

We stock a full range of VDUs, Printers,

Computer Stationery, Diskettes, Disk Boxes etc. LOW COST
all prices ex VAT. PR | NTE R M

Come and see us to discuss your requirements and have a demonstration. matrix printer £695

MICROSOLVE ——-

Microsolve Computer Services Ltd.
125/129 High Street, Edgware, Middlesex.
Tel: 01-951 0218/9 and 01-951 0210

daisywheel printer £2,115.

M11 junction 4/20 mins from Central London

¢ Circle No. 122
18 PRACTICAL COMPUTING January 1980

Graham Knott &
Jeff Orr have
now moved....

to new premises due to expansion
to accomodate larger stock and
workshop facilities for the

Microcomputer user.

Our new number is

ring us at any time for your
requirements

Pet 8k £550

Pet 16k £675

Pet 32k £795

2nd Cassette £55
Disk Units

Computhink 400k Random and Sequential
complete to fit 8k Pet (via

expandamem) £840
To fit 16/32n Pet (direct fitting) £895
800k Unit £1144
Memory Expansion
24k Expandamem for Pet £320
Interfaces
Uni-direc |-EEE to R§232 £89
Bi-direc I|-EEE to RS232 £140
Bi-direc 2 ported |-EEEtoRS232 £175
A/D Convertors
AIM 161 16 channel A/D convertor for
Apple, Aim, Nascom etc £130
Petset 1, AIM 161 including ait interfacing
requirements for Pet, complete £166

Stack Peripherals

Stack Joystick a balanced, calibrated unit
supplied with software and examples of use,
complete £25
New 625 Video Adaptor a vastly improved
625 video convertor for Pet, works
extremely well £25
Stack Page Printer Interface copies
screen contents onto 20m.a. loop complete
with software £25

APPLE
Apple-plus (b&w) 16k £770
2020 (colour) 16k £830
16k RAM upgrade £85
Printer Card £110
Communication Card £132
High Speed Serial Card £110
Disk Drive with DOS £398
Extra Disk Drive £355
Diskettes (10's) £30
KIM1 £99.95
MANUALS New Pet user manual £5
6500 Programming manual £5
6500 Hardware manual £5

PRINTERS

Teletype 43 pinfeed RS232 £860
friction RS232 £875
pin and friction RS232 £889
Anadex DP8000 £575
Decwriter IV LA34 £880

Perkins Elmer Pussycat
CRT Copier £839

Also Centronics Range, Texas
Instruments, Lear Siegler
Ring us for a quote on individual models.

Consumables

Anadex DP8000 paper (2000 sheets) 9.5"
x11" drop £15
Teletype 43 pinfeed paper (2000 ence
12”'x 11"drop £15
8.5 inch friction roll Box'A' quality eae
3.5" diam. rolls)

Box 'B' quality (12 x 3.5" diam rolls) £15

Box ‘A’ quality (6 x 5" diam rolls) £20
Box 'B’ quality (6 x 5"* diam rolls) £15
Cassettes

C15 cassettes high quality tape, 5 screw
cassette cases, per 10 £4.40

Disks & Diskettes
We supply 8" and 5.25" diskettes for all disk

drives. Please state your machine and we
can give you a quotation.

e.g. Pet 2040 £30 per 10
Computhink £30 per 10
Apple £30 pert0O
Horizon £30 pert0
Sorceror £30 per10

Many others in stock, both hard and soft
sectored.

Connectors
Pet User Port/!-EEE Port £1.10 each
Pet 2nd cassette Port 85p each

Hoods for User/|-EEE connectors £2.25
D.25 RS232 Connectors (State male or
femate) £3.00
D.25 Hoods £2.25
Demagnetiser

Curved head £4.00
if any requirements are not listed please
ring us as we may have them in stock.

All prices are +VAT at 15% and include carriage (unieas otherwise stated). Please make cheques payable to Stack Computer Services Ltd.

Stack Computer Services Ltd

290-298 DerbyRd, Bootle
Liverpool 20

PRACTICAL COMPUTING January 1980

¢ Circle No. 123

UNLEASH YOUR 5-100 MICRO COMPUTER

PLUG INA 10 MEGA BYTE DISC

CLENLO COMPUTING SYSTEMS

15 SOUTHUIEW COURT. THE WOODLANDS . BEULAH HILL. LONDON SE€15 3e)

FULLY COMPRTIBLE 5-100 BUS

(P/M SOFTWARE COMPATIBLE

1-80 BASED DISC CONTROLLER

COMPREHENSIVE DISC DIAGNOSTICS

EXPAang UP TO FOUR DISCS

OnLY £3400 EX V.ALT.
AOD-On DISC UNIT £1850

Now Converted to 50H2 forUK TV’s!

UPERBOARD Il

Full 8K basic and 4K user RAM

Built and tested

Fine +VAT

Features
Uses the ultra powerful 6502 microprocessor

8K Microsoft BASIC-in-ROM

Full feature BASIC runs faster than currently available
personal computers and all 8080-based business
computers

4K static RAM on board expendable to 8K

Full 53-key keyboard with upper-lower case and user
programmability

Kansas City standard audio cassette interface for high
reliability

Full machine code monitor and t/O utilities in ROM
Direct access video display has 1K of dedicated memory
(besides 4K user memory), features uppercase, lower
case, graphics and gaming characters for an effective
screen resolution of up to 256 by 256 points. Normal
TV's with overscan display about 24 rows of 24 charac-
ters, without overscan up to 30 x 30 characters

Extras

Power Supply & modulator £29.50 + VAT
610 Expansion board with 8K ram and dual
drive miniflopp chip

IP CO3P minifloppy disk, cased and with
power supply

Injection moulded case within 6 weeks

4K Ram upgrade kits

£188 + VAT
£312 + VAT
£35 + VAT

We are dealers for the rest of Ohio
scientific range of computers. The
widest range produced by any micro-
computer manufacturer, this
includes: —

= C2-4P A professional 4K basic in-
ROM computer cased and with
power supply

= C2-8P DF A 32K basic in ROM
computer with dual 8” floppy disk
drives for serious personal and
small business use

#f3-QEM A 32K computer with
3 micro-processors (6502, 6800,
280) and dual 8” floppy disk drives

Full business, word sprocessing and
cate base management is available
for all disk based systems.

Write for catalogue for further details

4 MORGAN STREET
LONDON E3 5AB

Solve your moss Storage problem today
Solve your data access problem today

TEL: O1-653-6028

® Circle No. 124

Software

Tapes at £5.50 + VAT
Homonyms*, Counter”, Trig
Tutor, Bar Graph, Definite
Integral, Basic Math, Presidents*,
Powers, Electronics Equations,
Spelling Quiz, Solar System,
Continents, Add Game, Math
Intro, Base Ten Converter, Math
Blitz*, Inventory Demo, Ratio
Analysis, Advertisement,
Statistics |, Salary Demo*,
Annuity 1, Annuity II, Interest
on Loans, Loan Finance,
Uneven Cash Flows, Personal
Destroyer, Hide & Seek, Star
Wars, Black Jack, New York
Taxi, 23 Matches, Lander’,
Etch-a-Sketch, Space War",
Battleship*, Crytography.
Tapes at £7.30 + VAT:—
Hangman, Mathink, Trend Line,
Straight & Constant Depreciation,
Address Book*, Checking
Account, Savings Account, Bio-
rhythm, Hectic.

Tapes at £11.00 + VAT:—
Word Processor ** , Programmable
Calculator, Tiger Tank

Basic Tutor Tape:— £26.40+VAT

Assembler editor with Manual
£25 +VAT

Extended monitor with Manual
£10 + VAT

TELEPHONE: 01-981 3993
TELEX: 261426 ATN.LOTUS SOUND

PRACTICAL COMPUTING January 1980

MAXIMUM CAPACITY COMMERCIAL SYSTEM
INCREDIBLE £1995+ VALUE!

THE PERFORMANCE LEADER!!
THE PRICE LEADER !!!

INTERTEC SUPE?BRAIN™

Dual Z80A 4MHz Vector Interrupt
64K RAM plus 1K 2708 PROM Bootstrap
TWO Double Density 5” Floppy Disk

@CP/M* Disk Operating System: The Industry Standard and Most Powerful

eMakes Thousands of inexpensive Compatible Applications Programs Available

From Scores of Suppliers (Including Us)

eComes With: Powerful Editor, Assembler, Dynamic Debug Tool, Disk Formatter —

We Also Have Low-Cost High-Performance Business Software

eBEWARE of One-Source Non-Standard Operating Systems Offered by Others —

Be Free to CHOOSE, Not at the Mercy of One Supplier!

eANSI Standard FORTRAN, COBOL, BASIC, APL, APPLICATIONS SOFTWARE Available
From Any and All CP/M Software Houses at Affordable Cost

@S-100 Bus VIA Direct Connection — Cost Effective Flexible Expansion

eMakes Scores of Competitive Hardware Boards & Functions Available From

Dozens of Manufacturers: Be Free to CHOOSE, Be Independent!

eUnlimited Practical Expansion: 2 DSDD 8” Floppies 2: 4Mbyte; 8-120Mbyte Hard

Disk; Colour VDU, Plotter, Modem, Mainframe Interface, etc. Using Optional S100 Extender
eMAKES EXCELLENT DISTRIBUTED PROCESSING GOMPUTER ON ANY MAINFRAME

@TWO High Quality Commercial Grade BASF 5” Diskettes: 160K Each (320K Total)

e2 Double Density Minifloppies; Add Two More inexpensively; Data Files
File Security, File Copy, Convenient Operation in All Applications /

@VDU High Resolution, Fully Programmable, Dual Keyboards of Highest Quality

eFull Upper/Lower Case ASCi! 128 Set With Limited Graphics; 64 User
Definable Function Keys, Programmable Cursor & Reverse Video

e25 Lines by 80 Characters 8x8 in 8x12 Field; Easy Reading Full Size 12”
Screen; Numeric and Control Keypad Separate

@DUAL Z80A PROCESSORS — TWO Board Modular Easy-Maintenance System
eDisk and Processor Use Separate Z80s: Computing Can Continue During Disk Operations etc.; Transparent
Bootstrap Allows Full 64K Memory
eTwo Boards: Computer, VDU & Power Supply: Simple Servicing by Board Replacement - On service
Contract or Send in Boards Yourself

@All In ONE Smart Portable Lightweight Console (45 Ib): Just Add A Printer!
eAny Size Printer, Any Function: £300 — £2500; Std., Daisy, Two Colour, Full Graphics ON Standard
RS-232 CCITT Serial or TRS-80 Parallel

@Can You Find Another Commercial System Which Outperforms This One?

@Make No Mistake About It — The Others Are Mere Students and Cannot Compete
With This Year’s Honour Graduate, Intertec Superbrain: Top of All Classes!

@All Enquiries Invited From Commercial End-Users and Dealers

ICARUS COMPUTER SYSTEMS
E Floor, Milburn House, Dean Street, Newcastle on Tyne (0632) 29593, 28632

See us at Booth 55 International Business Show 1979

23rd October-1st November National Exhibition t Yes, that's the one-off price, NOT the Delivery Date mM!
Centre Birmingham * Registered Trade Mark of Digital Research Corporation
3

of California, U.S.A.

e Circle No. 126
PRACTICAL COMPUTING January 1980 21

DISKS : LTT : MEMORY : DISKS : LTT : MEMORY : LTT

GODBOUT Computer Products

High quality, fast (4 MHz), reliable static S-100 memory
boards and other products e.g. Kit Ass
2706 EPROM chip £6.25 n/a
2716 EPROM chip re) n/a
Econorom 2708, 16K EPROM (N@ EPROMS) £65
Econorom 2716, 16K EPROM (N@
EPROMS), 8K RAM (N@ RAMS)
Econoram Ila, 8K

Interfacer 2 full RS232 serial 1/O
Econoram IV, 16K, 1 x 16K
Econoram Vila, 16K, 1x 8K + 2x 4K
Econoram Vila, 24K, 2x 8K + 2x 4K £230 £249
Econoram Xiltla, 32K, bank select,2x 16K £315 £339

Software for CP/M

QUALITY PACKAGES DIRECT FROM U.S.A. .0.a.
£45

CBASIC—2

Extended Disk Basic for Commercial work
WORDSTAR

Ultimate in micro Word Processing Software
SELECTOR III-—C2

Best selling DBMS
SUPERSORT | (relocatable & executable)
SUPERSORT II (executable only)

£55— 675
£80 £99
yo) 21) 45)
£150 £169
£165 £185

SUPERSORT III (as 11 but without Select/Exclude)
Sort/merge and select/exclude

WORDMASTER

Superior full screen text editor

TEX-WRITER

Output formatter
IBM-CP/M COMPATIBILITY
3740 data exchange with CP/M

CASH WITH ORDER

ADD 50p/Item P&P (Min £1) and VAT (15%)
STATE Computer and Disk size/format
Due to Dollar fluctuations, Prices subject to change without

notice.

Telesystems Ltd

P.O. BOX 12, GT. MISSENDEN BUCKS HP16 3DD
02406 5314

¢ Circle No. 127

V&T ELECTRONIC

EPROMS — All Ex Stock
2532 5V 4Kx8
2516 only 2K x8
2708 1Kx8
RAMS
4116 16K Dynamic 200 ns
4116 16K Dynamic 300 ns
2114 1K x 4 Static 200 ns
2114 1K x 4 Static 450 ns
TRS 80 16K Upgrade Kits
CPU
Z80A
MC 6800
MC 6802
6502
BUFFERS
744 LS 244
744 LS 240
744 LS 245
PRINTER
Anadex DP 8000 Mk II
ALL ITEMS EX-STOCK
Please Add 15% VAT
40p P&P orders under £10.00

iS)

LTT : MEMORY : DISKS : LTT : MEMORY : DISKS : LTT : MEMORY : DISKS: LTT

EXTRA LOW PRICES ON QUALITY DISKS

Brand name diskettes stocked for most micros.

Pack of ten 5% in. disks, £19. Ten packs ( 100 disks), £175.
Pack of ten 8in. disks, £23. Ten packs (100 disks), £210.
When ordering please specify whether you require hard
or soft-sectored diskettes, and if hard-sectored, the
number of sectors.

Anadex DP8000 Printer. Ready to go! Includes
RS232 cable, 1,000 sheets continuous stationery
and Securicor delivery within UK. Only £525.

All prices given include postage and packing. (overseas

add £10). Just add VAT. Send 10p stamp for details.

Quantity discounts available on application. Credit

terms (nett 30 days) given to large companies and

Government establishments.

Mail Order ‘phone: 01-828 1785 LTT ELECTRONICS
8 Waldegrave Road
London SE19

LTT : MEMORY : DISKS : LTT : MEMORY : DISKS : LTT : MEMORY : DISKS : LTT

iSKS : LTT : MEMORY : DISKS: LTT : MEMORY : DISKS :
¢ ¢ Circle No. 128

V&T ASSEMBLER

New improved V&T Assembler now available
for Nascom 1 & 2.

The only fully relocatable assembler for the
Nascom range — (easily converted to other
Z80 systems).

— Supports all standard mnemonics & pseudo
ops: — DEFB, DEFS, DEFW, DEFM, EQU & ORG.
Source, object & symbol areas fully programm-
able.

Now includes —

Symbol table

Operation under T2, T4, B Bug, Nasys

Label find & change
Relocating source reader
Improved keyboard routine, etc.
£12.50 + VAT
Existing V&T Assembler owners may return orig.
tape to obtain uprated version.
S.A.E. + £2.50 inc VAT

V&T Superdeck — CPU Controlled £110.00
Exidy Sorcerer 16K — £670 + VAT — includes
basic Rom lastest edition. ,

Please see previous Nov. Ad for full details

V&T ELECTRONICS 82 CHESTER RD., LONDON N.19 5BZ
01-263 2643

* Circle No. 129

PRACTICAL COMPUTING January 1980

NEW LOW PRICE FOR
LEVEL II BASIC 16K

wm | TRS-SO Microcomputer

the world’s biggest selling personal microcomputer

This is a fantastic opportunity ** Level refers to version of BASIC
toowna TRS-80 personal computer language.
microcomputer. Designed and ** 16K Is size of Random Access
built by TANDY, the TRS-80 is __ Memory Capacity.

the world’s biggest seller, with ** All systems include 232 page

THERE 1S ONLY ONE PLACE YBU CAN FIND IT
TANDY

over 100,000 in use. a & games cassette
The‘silicon chip’ revolution is No prior knowledge of computing
here, now, at your nearest is required to use the TRS-80.

TANDYstore. If necessary you + Fully wired and tested

3). simplyadd-on extramodulesto —NOTakit.

», \ Suit your individual require- + Designed and Manufactured by
ments. SeeaTRS-8O0at your TANDY Corporation.

Total £596:85 Oldprice £752:81

inc. VAT at 15°0

TRS-80 Expansion is easy!—Just add the units to suit your needs.

Old Price New Low New Low
incl. Price Price
15% VAT (less VAT) incl. VAT SAVE
a +

EUS £228.85

Offers subject to avariabulity, as Access, Barclaycard and Trustcard welcome.
Instant credit available in most cases. guygmmmes) Check your telephone directory for your nearest store.
OVER 170 STORES AND DEALERSHIPS NATIO

ACK INTHE USA MAKERS O RLD'S B LLIN

BRINGING HIGH TECHNOLOGY DOWN TO EARTH

[ Please send full details and new low prices of TRS-80 systems. = meen
NAME
l ADDRESS
OO ae ae
\ TANDY CORPORATION, BILSTON ROAD, WEDNESBURY, W. MIDLANDS, WS10 7JN.
ee se ee ee eee eee eee eee eee eee ee

® Circle No. 130
PRACTICAL COMPUTING January 1980 23

CAMBRIDGE COMPUTER STORE

We can help you select the right system for your applic-
ation. Here in Cambridge your choice won't be limited —
we'll demonstrate as comprehensive a range of microcom-
puters as you'll find anywhere in the ULK.:

TANDY TRS-80
COMMODORE PET
APPLE Il
N-S HORIZON
CROMEMCO
SORCERER
ACORN
NASCOM-1

Stop Press: dramatic reduction now in prices of TRS-80,
APPLE || and HORIZON systems. Where possible we
deliver off-the-shelf, to any location.

The store is open 6 days a week from 9—5.30 with demon-
stration systems always in Operation. We offer a professional
standard of advice and after-sales support and we're ready
to discuss your application any time.

CAMBRIDGE COMPUTER STORE
1 Emmanuel Street, Cambridge (0223) 68155

* Circle No. 131

ide
Lh = Ch a

BEL

ABEL COMPUTER SYSTEMS LIMITED
5 HANLITH-WILNECOTE-TAMWORTH:STAFFS:B77 4BP

Apple Symbolic Assembler

2 pass assembler with good
manual. Requires 32K system

and diskette drive

Software on diskette £26.45
Apple Games

(with comprehensive instructions)

8 games on diskette £12.50
8 games on cassettes £10.00
Diskettes (single sided)
Standard quality each £2.35
Superior quality each £3.25
Cassettes per 10 £3.90

PRICES INCLUDE VAT
Please add 30p p&p to order

° Circle No. 132

+ MICROS = SOFTWARE

Business systems available now for the TRS 80

Sales Ledger

(OPEN !TEM/DEBTORS ANALYSIS/STATEMENTS/INVOICES/VAT/DAYBOOKS etc.)

from Eo 150

Purchase Ledger (OPEN ITEM/CREDITORS ANALYS!IS/REMITTANCE ADVICE/VAT/DAYBOOK etc.) from & 150

Invoicing
Stock Control

Payroll

Nomina] Ledger

(Available shortly)

(UPDATES SALES LEOGER/DOWNDATES STOCK/MAINTAINS BACK ORDERS)

(iSSUES/RECEIPTS/MOVEMENT, USAGE, VALUATION, RE-ORDER REPORTS etc.)

&'75
& 200

(WEEKLY, MONTHLY, CASUAL STAFF/BONUS SCHEMES/COIN ANALYSIS/PAYSLIPS etc.) dD 2 i 8

12 MONTH WARRANTY ON ALL PACKAGES - TAILORED SYSTEMS TO YOUR REQUIREMENTS

FOR THE BEST IN PROFESSIONAL MICRO BUSINESS SOFTWARE CONTACT US DIRECT 'OR CALL YOUR-NEAREST TRIDATA DEALER FOR A DEMONSTRATION.

CAMBRIDGE COMPUTER STORE (CAMBRIDGE) 0223 68 155

COMPUTER DEVELOPMENT SERVICES (SWANSEA) 0792 26085
0767 81195

0424 220391

ELECTRON SYSTEMS (SANDY, BEDS.)

A. J. HARDING (BEXHILL, E. SUSSEX)

KATANNA MANA4GEMENT SERVICES (CHELMSFORD)
OPTRONICS (TWICKENHAM)

0245 76127
01 B92 8455

GPW ELECTRONICS LTD (PORTSMOUTH) 0705 693341

Tridata Micros Ltd.
Smithfield House
Digbeth
Birmingham B5 6BS
Tel:021 622 6085

13-19 MILFORD STREET, SWINDON Make more time available to
WILTSHIRE :
— Tel: (0793) 42615

SN1 1DW
Telex: 449703

enhance the quality of your
life and improve your business

COMPUTER SALES @ HARDWARE @ SOFTWARE @ CONSULTANCY e MEDIA @ STATIONERY ETC

For less than 25p an hour for just one year you can
COMPUTERISE YOUR BUSINESS NOW!
EVERYTHING YOU REQUIRE TO START

COMPLETE — READY TO OPERATE.
Incl. VAT, Pkg. & Delivery. Nothing extra to pay:

£2,300

@ MICROCOMPUTER WITH 48K RAM (Memory)
@ DUAL DISK DRIVES (Storage up to 400K)
@ DOS DISKETTE (Disk Operating System)
@ BOX OF 10 BLANK DISKETTES
@ PRINTER WITH TRACTOR FEED
@ BOX OF CONTINUOUS STATIONERY/LABELS
@ EVERYTHING COMPLETE WITH MANUALS

on Diskettes in a Library Case

comprising:

SALES/PURCHASE LEDGERS QUOTE/ORDER/INVOICE
BANK RECONCILIATION STOCKS / SHARES ANALYSIS
STOCK CONTROL MAILING LIST GAMES PACKAGE
This package illustrates how to solve many of your business problems.
They may or may not be suitable for your type of application but they will

help you develop your own software for virtually any type of business.
Worth over £500 this package is enclosed FREE

FREE Programs worth over £500 =

SOFTWARE
We are pleased to announce that we have been appointed
Exclusive Distributor for UK, Europe & the World for
GRAMA WINTER SOFTWARE
for TRS 80, Apple, ITT 2020. Also dealer for Pet, Z80, SWTP

Fully integrated suite of 30 complete business programs
Usual cost of such Quality Programs would be £2500+
Complete support, updates, NHi/Tax changes etc

Write for details.
Special introductory price ...£575 ...

CONSULTANCY

Please write or telephone if you require advice on
BEGINNING or EXPANDING your computer installation.
Software programs customised to your requirements.

OUR BUSINESS EXISTS ON IMPROVING YOUR BUSINESS.

inclusive of VAT.

Please send Full Details & Price Lists My requirements are for:
HOME [] HOBBIES [] STUDENT [J BUSINESS [}
Name
Street
Town —_: eRe
County

Post Code
Telephone

Name of Co :

Position

PO/Chq No oe
(Payment by Barclaycard / Trustcard / Access etc., can be rey

PRACTICAL COMPUTING January 1980

We are continually adding new products to our range and would be
pleased to receive your enquiries. @ Quantity Discounts available.

TRS 80 ex. VAT inc. VAT
AK Level 2 (c/w K/bd, VDU, T/Rec) 434.78 500.
16K Level 2 (c/w K/bd, VDU, T/Rec) 500.00 57/5.
OK Interface (to add printer & disk drives) 195.66 225.
16K Upgrade kits (for k/bd or interface) 65.22 75,
Disk Drives, single (upto 200K) 260.88 300.
Disk Drives, dual (upto 400K) 608.70 700.
Disk Drives, dual (upto 1000K) 1173.91 1350.
Disk Drives, dual (up to 2000K) 1521.74 1750.
Disk Drives, cable 2 & 4 way from 21.74 75),
Anadex Printer, Tractor feed 434.78 500.
Printer cable for Anadex/Centronics 274 25.
APPLE I ITT 2020
16K (c/w Keybd & Palsoft ROM) 608.70 700.
16K Upgrade kits 65.22 i’),
Disk Drive, single with cable 326.09 17/5).
Printer Interface 108.70 125.
Anadex Printer, tractor feed 434.78 500.
Colour TV ITT 340 239.13 275)
COMMODORE PET
2001-32N (New keyboard &32K) 673.91 775.
2040 Dual Disk Drive 343K 673.91 775.
3022 Printer with graphics 521.74 600.
Printer interface and cables, each 21.74 25.
MEDIA LIST
5%"' Verbatim from (Qty 10) 17.39 20.
5¥%"’ Dysan from (Qty 10) 26.09 30.
8%" 3M from (Qty 10) 30.44 35.
Blank 5%" &8%"' Diskettes, Soft/Hard Sectored, Formatted/ Unformatted.

We have Diskettes to suit many systems. When ordering please quote:
SYSTEM MANUFACTURER, MODEL, MEDIA TYPE, AND DISK SIZE
Available in smaller or larger quantities.

STATIONERY Listing Paper, Continuous Forms, Labels.
£10

Listing paper 11” x 8%”, white/green music ruled, boxed 2000

Labels 2%" x 1%", white, fanfold, £5 per 1000 . . .10,000 for mo

Post/Packing/Insurance extra. Delivery by Registered Post, Securicor, etc.

Price’ List correct at time of going to Press, subject to change without notice. E.& O.E.
Standard Warranties apply

Your enquiries assist us in forward purchasing.

Requirements Description inc. VAT
Microcomputer :

Upgrade Kit

Interface

Disk Drive

Printer :

Cable/Interface °......

Cluster System :

Colour TV

Media

Stationery Levee Hastie
Software

Post/Pkg/Ins
PC/PCW/L

(please tel. for cost) ............

e Circle No. 135
25

The small business system
that won't let you down

VECTOR MZ FROM COM PUTASTORE

Computastore has
combined the powerful Vector
MZ microcomputer with the
reliability of proven accounts
packages to bring you the
benefits of a Small Business
Computer at a price you can
afford. With a high speed
printer, the total system costs
£5500, including installation
and training — no extras to pay.

The integrated accounts
packages provide the flexibility
and ease of operation that first
time users demand. Operator
training is provided at YOUR
premises, using YOUR data to
get your system working within days. And because our accounts software has been
developed in-house, the standard packages can easily be tailored to meet your needs exactly.

@ SALES LEDGER: Open item system, produces TECHNICAL OVERVIEW:

statements and current aged debtors balance at any Vector MZ: Industry standard CP/M
time — not just at month end. operating system, 48K RAM, 630K Disk Drives,
m@ PURCHASE LEDGER: Open item system, Fast sec ligase leiatiaaats $100 bus.
produces aged creditors balance and remittance Mindless Terminal:

advices at any time - you choose the items you High quality 80 x 24 upper and lower case
want to pay. display, Typewriter style keyboard, with

@ NOMINAL LEDGER: Links with both sales "eric keypad.

and purchase ledgers. Compares actual with budget, Texas Instruments 810:

and with same period previous year. 150 c.p.s. high quality dot matrix printer.

@ ONE OFF SOFTWARE: We will be pleased to

quote for any other commercial application. ONLY 32K Vector MZ complete

with 630K disk drives,

m@ WORD PROCESSING OPTION: Combine £1,700 CP/M, C/BASIC and NAD.

your word and data processing on the same system.

Full Range of Low Cost Accessories by Mail Order.
“Barclaycard and Access welcome.

HARDWARE, SOFTWARE and ACCESSORIES
sold either as complete systems or separately.

All goods in stock NOW, so Software That Means Business
why not call in for a 16 John Dalton Street
demonstration, or ring or write Computastore Manchester M2 6HG

for further details. Tel: 061-832 4761

WALES LEADING
SYSTEMS HOUSE

Incorporating { Microcourier}

14 CHEPSTOW ROAD
NEWPORT, GWENT.
50528 / 841691 / 63310

At Micromedia we are usually asked for Complete Business Systems, here are a few examples.

Accounting Package Sales Invoicing / Credit Controls
Payroll on Alpha Micro, with 10 Megabyte Disk, visual

display unit and printer.

Purchase Accounts, Sales Accounts, Payroll on Cromemco

System in with work station, visual display unit and

180 c.p.s. printer.

Word Processing, Payroll, Accounts, on North Star Horizon

with printer visual display unit and additional monitor.

Call us for a quotation on:
Cromemco ti & i
North Star Horizon

Alpha Micro

Compucolour it

Commodore Pet
SWTP_ 6800

Microstar 45

448.75

APPLICATION SOFTWARE
Mailing Lists
Data Base Management
Accounting Suites
Stock Controls
Simplex Linear Programming
Personel Records
Fleet Maintenance Records
Word Processing
Pert (Critical Path Analysis)
Purchase Ledger
Sales Ledger
Medical Records
These are a selection from the
range please call us to discuss
your particular application.

We specialize in systems for Business Industry and Education and have

Visual Display Units

Adds Regent 20

Adds Regent 25

Adds Regent 40

Cifer 2600

Dec VT 100

Elbit 1920/30

Elbit 1920/30x

Infoton

Lear Siegler ADM 3A

Newbury Lab Range
From

Pericom 6801

Pericom 6802

Pericom 6803

Printers

Anadex DP800
SWTP_ PR 40
OK! E T 5200
Teletype 43 KSR
Dec LA 34

Dec LA 36

Dec LA 120 KSR
Diablo 1640 RO
Diablo 1640 KSR
Texas 743

Texas 810

Tally Range from

specialist staff to discuss your applications.

Odds ‘n Sods

M22 Paper Tape Reader :
; “ Punch pie
M33 Paper Tape Reader 450
M63 Paper Tape Reader
Punch 1495
Servogor Graphic Plotter
2750
Sigma Graphic Option
Controller 2168
Single side mini Diskettes
Per 10 30
Single side 8’’ Diskettes 35
Per 10 35
C12 Casettes Per 10 475

Large range of computer books
send SAE for list.

OEM TERMS & QUANTITY DISCOUNTS AVAILABLE WRITE FOR DETAILS

PRACTICAL COMPUTING January 1980

e Circle No, 137

MICROTEK
COMPUTER
SERVICES

FOR:
EQUINOX 300
NORTH STAR HORIZON
IMS 5000

PLUS:

DIABLO, ELBIT & TEXAS PERIPHERALS.
SOFTWARE PACKAGES FOR:

STOCK CONTROL

ACCOUNTING AND VAT

CLIENT INFORMATION & MAILING

BUDGET CONTROL

CAR STOCK BOOK

IMPORT CONTROL

PAYROLL

"LOCATE-A-CAR’ SYSTEM, ETC.

50, Chislehurst Road, Orpington,
Kent.
Tel: Orpington 26803

¢ Circle No. 138

cost north

Computers in th

‘The Vector Graphic MZ

4MHZ Z80A CPU
48K ram

One Roof
H@8 COMPUTERS LTD

Stock a full range of
Micro Computers adie :

A personal computer that
opens the world of
WA wos to your
own fresh ideas!

F chanics MZ-80K

And now a major distributor for

ACTSYSTEM8&00

The most advanced, least expensive computer ever
created.
AVAILABLE FROM

HB COMPUTERS LID

22 NEWLAND STREET, KETTERING NORTHANTS.
Tal. (0536) 83922 & 520910 Telex 341297

¢ Circle No. 139

ieboraey
e world.

amet

The Vector Graphic System B

630K Bytes disk storage Plus a large range of CP/M compatible software Complete Vector MZ system plus:
Serial port and two paralle! ports including Fortran, Cobol, Macro assemblers etc. Vector Mindless terminal

%*Prom/ram Board with monitor
%*MDOS Operating system
3Z80 Assembler

Basic Interpreter

Flashwriter 2 video board (24 x 80) &
Software driver on prom *

MZOS North Star compatible DOS &
3CP/M configured by Almarc

DATA SYSTEMS iro

906 Woodborough Road, Nottingham. Telephone: (0602) 625035

¢ Circle No. 140
PRACTICAL COMPUTING January 1980

5?
‘

SOGEeeaeasce

ADDACOMPUTERS COMPUTERLAND COMP SHOP

Ealing,London W5. Nottingham. New Barnet, Herts.
Tel:01-579 5845 Tel:0602 40576 Tel:01-441 2922

BITS & P.C.s Manchester 1. COMPUTER MANIA
Wetherby. Tel:061-236 4737 Great Milton,Oxon.
Tel:0937 62592 Birmingham. Tel:Great Milton 729
BUSINESS & LEISURE Tel:021-6227149 C.C. ELECTRONICS
MICROCOMPUTERS Glasgow. Torquay.

Kenilworth. Tel:041-221 7409 Tel:0803 22699
Tel:0926512127 = TARGETELECTRONICS DATRON MICRO CENTRE HAPPY MEMORIES
THE BYTE SHOP Bristol. Sheffield.
liford,Essex. Tel:0272 421196 Tel:0742 585490
Tel:01-554 2177 THE CAMERACENTRE ELECTRONIC SERVICES
London W1. Barrow-in-Furness. Sheffield.

Tel:01-636 0647 Tel:0229 20473 Tel:0742 668767

PRACTICAL COMPUTING January 1980

SGEGgeaegeae es
ce ee . = The prices include a ready-built 48-key
: LICON keyboard.

ees NASCOM UK DISTRIBUTORS

BETTER VALUE
THAN EVER

£6 itis, without doubt, a good basic kit offering good
potential and facilities . . . it represents one of the best

value-for-money kits available IF Vincent Tseng -
Practical Computing, Jan. 1978.

££ The Nascom-1 Z80 based board computer must be a
strong candidate for the most successful ever British
computer 9J Martin Banks - Computer Weekly, 30th Nov. 1978.

&6 Overall, the Nascom-1 is an excellent unit. I've been
using my Nascom for about 5 months (it worked first time)

and! am very happy indeed with it 9J Editor
Computing Today, Nov. 1978.

££ Nascom-1 is the best thing that’s happened to the British
microcomputer industry_it was the product that set things

moving here JJ Comment by the Editor of

Personal Computer World

at the PCW Show, Sept. 1978.

This is what the media said about Nascom-1
when it was £200. Now, with over 15,000
systems in operation world-wide and the new
low prices, the Nascom-1 is an even better buy.

And look whatelse you get:

A 12” x 8" PCB carrying 5LSI MOS
gg packages, 16 1K MOS memory packages and

33 TTL packages. There is on-board interface
for UHF or unmodulated video and cassette or
teletype.

The 4K memory is assigned to the operating
system, video display and EPROM option
socket, leaving 1K of user RAM. The MPU is the
standard Z80 which is capable of executing
158 instructions Including all 8080 code.

NM/PC/4
ELECTROVALUELTD INTERFACE LOCK DISTRIBUTION + PIPS COMPUTER
Egham, Surrey. COMPONENTS Oldham, Lancs. SERVICES
Tel:07843 3603 Amersham, Bucks. Tel:061-6520431 Whitley Bay.
ELECTROVALUELTD Tel:0240322307 MICRODIGITAL Tel:0632 482359
Manchester M19. A&GKNIGHT Liverpoo! L2. P & O COMPUTERS
Tel:061-4324945 Aberdeen. Tel:051-227 2535 _—‘Beifast.
ELEYELECTRONICS Tel:0224630526 PHOTOACOUSTICS STRATHAND
Glenfield, Leics. Watford, Herts. Glasgow.
Tel:0533 871522 Tel:0923 32006 Tel:041-5526731

Southampton. NASCOM MICROCOMPUTERS LTD.

Tel:0703 39267 92 BROAD STREET, ff mM
HENRY’S RADIO CHESHAM, BUCKS.

London W2. TEL: 02405 75155 Nascom Microcomputers

Tel:01-723 1008
e Circle No. 141
29

STEP INTO THE 1980's
WITH SHARP’S NEW

PRINTERS FOR PET

Plug connectable. 2001 and 3001

Full Character Set and Graphics and
Cursor Signs

Variable Character Size

Reverse Print

Paper roll or Reversible Tractor Feed
£ sign

100-120 CPS Bi-directional
5x7,6x7,9x7, Dot Matrix

52-80 Print Positions

Alternative Interfaces — RS232 and
Centronix

PARAMETERISED

COMPUTER
SYSTEMS LTD

2HARPS:
‘SHARP:

SHARP:

| SHARPSHaRp:

SURPSHARASHARPS Hare
SUARESHARPSHaRPSHany
HARP SHARPS TR SHAR!
ete seesiAR Stan

Built-in Clock and Sound Circuits
Clock circuit: time is displayed according
to program.

Sound circuit: 3-octave sound signals
for aural confirmation according to
program.

SHARP MZ80K

ASCII standard :

Alphabet (capital and small letters)

Graphic symbols

* Z-80 based CPU

* Internal memory expansion up to 48K
bytes of RAM

* Fast reliable cassette with tape
counter —
1200 bits/sec

* §0 pin universal BUS connector
for system expansion — printers,
floppy discs etc.

CRT Display

This unit is equipped with a 25cm (10'')
monochrome CRT for up to 1,000 letters
(40 letters x 25 lines). Processing results
can be displayed on the CRT, and it is
possible to program and edit (addition,
deletion, etc.) while watching the
Operation for confirmation

Available from
FLETCHER, WORTHINGTON LTD.

PRICES FROM £450

250 Brompton Road
London SW3

Branches at:
PROGRESS HOUSE LOW MILLS ROAD
LEEDS 12

55 GARSTANG ROAD
CECIL ROAD PRESTON
HALE TEL: PRESTON 56544
ALTRINCHAM
CHESHIRE
TEL: 061-928 8928/9 & 4113

TEL: LEEDS 633233

e Circle No. 142 ¢ Circle No. 143

: | 33 Cornwall Buildings, Newhall St, Birmingham B3 30R
Telephone 021-233 2407

APPLEs for enthusiasts, small businesses,
COMPUTERS LTO.

Estate Agents and Software Tailors.
SIGN OF GUARANTEED QUALITY

Enthusiasts: a pack of 70 exciting games, on five.
disks, including dazzling graphics, games paddles,
music and dance. All for £80.00.

Small Businesses: PAYROLL. This package is
produced by Algobel Ltd., the sign of guaranteed
quality. £235.00.

Software can be tailored by arrangement with
our software suppliers.

Estate Agents: Property & Applicant Matching
System. £6

W/Proc to print Property Details and
standard letters

Software Tailors: we offer a very appealing finance
proposition for you to buy or rent your computer
through us.

In addition, we delegate all enquiries for

ACCOUNTANTS PACKAGE £5,250.00

(Rental £115.92 monthly, or Lease Purchase £134.03
monthly)

The system provides an extensive and
comprehensive replacement to the normal routine
of an Accountancy Practice.

GUARANTEED SOFTWARE

Produced by Algobel Computers Ltd, using the
most up-to-date computer techniques.

30°

programming work which is not to be covered
by our mark of guaranteed quality.

RENT AN APPLE

this appealing proposition starts at £38.66 monthly
(for a complete 48K system with 2 disc drives).
Tax position: Rentals can be offset against gross
revenue.

Lease Purchase: This proposition starts at £44.95

monthly. Title passes on completion of agreement.

GUARANTEED COMPUTER SELECTION

Having examined and tested without prejudice,
all the computers available and based in the U.K.,
we have approved the merits of the following
schedule, which is fully included in the quoted

price.

CROMEMCO 2Z-2D computer, ADM terminal and

Centronics printer.

e Circle No. 144
PRACTICAL COMPUTING January 1980

ROCKWELL AIM65
as you like it!

There are many ways totake AIM

= "te

~e AIM 65. The original bare-board version as it comes from
aS Rockwell with: 20 col. printer, 20 ctr alphanumeric display, 54
Qwerty Keyboard, TTY and dual cassette interfaces, 1K or

Sy 4K on-board RAM options, powerful 8K monitor in ROM.
This 6502 pip based product comes complete with full

documentation, fully assembled and tested.

Price: A65-100 (with 1K RAM) £249.50

aims ao > A65-400 (with 4K RAM) £315.00
ss
o AIM 65C. This ‘special’ packaged system developed by
183) PML, for those of you who wish to limit your hardware
involvement to the attachment of the 13 amp plug. (We leave
it off especially). It comes with 4K RAM, power supply,
assembler or basic and desk top case.
Price: A65-500C (basic) £485.00
A65-600C (assembler) £475.00

14300 AIMANCE TERA

oe ee ek on
Weare ereee A-¢ 0
ae Teal Pik en eat Tien | rae

poe aravavives

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ae
[i |

PDS 65. The portable development system is another PML
product designed for those of you who require the convenience
of this novel housing. It comes supplied with 4K RAM, power
supply, assembler, basic and briefcase housing. Also offered as
an option is a 300 baud acoustic coupler.

Price: PDS-65 £750.00

PDS-65/1 £950.00

DESKTOP CASE. For those of you who already have AIMs
or who prefer to do it your way. This plastic case includes
space for a power supply (also available) and 1 additional
expansion module.

Price: £60.00

BRIEF CASE. A brief case with a specially designed
vacuum formed plastic insert for use as a convenient
equipment housing for use with AIM 65 or many other bare-
board systems.

Price: £85.00

Options:

assembler in ROM £60.00
basic in ROM £70.00
power supply £40.00
acoustic coupler £200.00
expansion motherboards A65-KIM £80.00

A65-6800 £135.00
A65-S100 £132.00

NOTE All prices are subject to change
without notice and are exclusive of V.A.T.

Portabie
Microsystems
Limited

Ask about our similar models using Nascom 1

or 2 microcomputers.

P.S. We will shortly be announcing a floppy
aise and a range of modules for use with AIM
5.

PRACTICAL COMPUTING January 1980

Forby House, 18 Market Place,
Brackley, Northants, NN13 5SF
Telephone Brackley (0280) 702017

Telex Micro 83147
e Circle No. 145

OOOR TUNES £17.13 + VAT
Waddingion’s Videomaster announce a doorbell that doesn't
go Briringgg, Ding Dong or Bezzzz Instead plays 24
different classical and popular tunes ‘t will play the tune
you select for your mood, the season of the wisitor you are
expecting to call. Door tunes 1s not only great fun and a
wonderful ice breaker, but is alsa very functionally and
beautifully designed to enhance your home. There is
something for Chrismas, something for your continental
visitors of your relations from the states, and even
something for the Queen. Door tunes is easy to install and
has separae controls for volume, tone and tempo

PROGRAMMABLE £29.50 + VAT.
COLOUR CARTRIOGE T.V. GAME.

The TV game can be compared to an audin cassette deck
and is programmed to play a multimude of different games
w COLOUR, using varius plug-in cartidges At jong last a
TV game 1s available which will keep pace with improving
technology by allowing you to extend your library of games
with the purchase of addiuonal cartridges as new games
are developed Each cartridge contains up to ten different
action games and the first cartridge containing ten sports
games 1s included free with the console. Other cartridges
are currently available to enable you to play such games as
Grand Pnx Motor Racing, Super Wipeout and Stunt Rider
Further cartridges are to be released later this year,
incuding Tank Bartle, Hunt the Sub and Target. The
console comes complete with two removable joystick
player comrols to enable you 10 move in all lout ditections
tup/downiright/lefil and burlt into these joystick controls are
ball serve and target fire buttons Other features include
several difficulty option switches, automatic on screen
digia! sconig and colour coding on scores and balls.
Lifelike sounds are transmated through the TV's speaker,
simulating the actual game being played

Manufactured by Waddington’s Videomaster and
Quaranteed for one year

24 TUNE DOOR CHIMES

EXTRA CARTRIDGES:

ROAD RACE — £8.87 + VAT.

Grand Prix motor racing with gear changes, crash noises
SUPER WIPEOUT - £3.17 + WAT.

10 different games of blasting obstacles olf the screen
STUNT RIOER - £12.16 + VAT.

Motorcycle Speed trials, jumping obstacles, leaping various
rows of up to 24 buses etc

NON PROGRAMMABLE TV GAMES

6 Game — COLOURSCORE It — £1150 + VAT.
10 Game COLOUR SPORTSWORLO £22.50 + VAT.

CHESS COMPUTERS

STAR CHESS — £85.65 + VAT
PLAY CHESS AGAINST YOUR PARTNER.

using your own TV to display the board and pieces. Star
Chess 1s a new absorbing game for Iwo players, which will
interes! and excite all ages The uni plugs into the aenal
socket of your TV set and displays the board and pieces in
full colour for black and whitel on your TV screen, Based on
the moves of chess. It adds even more excitement a
interes! 10 the game, For those who have never played,
Star Chess 1s a novel introduction 10 the classic game of
chess For the experienced chess player, there are whole
new dimensions of unpredictabilny and chance added to
the strategy of (he game Not only can pieces be taken in
conventional chess type moves, bul each piece can also
exchange racket fire with as opponents, The unit comes
complete with a free 18V mains adaptor, fult instructions
and twelve months guaraniee

CHESS CHALLENGER £98.50

PLAY CHESS AGAINST THE COMPUTER.

The stylish, compact, portable console can be set to play at
seven different levels of abilay trom beginner to expen
including “Mate in 1wo" and “Chess by mai” The compuier
will only make fespanses whith obey international chess
rules. Castling. on passant, and promoting a pawn are all
included as pan of the coniputer's programme Ni is
possible to enter any given problem {yom magazines or
newspapers or alternatively establish your own board
position and watch the computer react, The posmions ot al
pieces can be verified by using the computor memory recall
bution

Price includes unt with wood grained housing, and
Staunton design chess pieces. Computer plays’ black or
whine and against aselt and comes complete with a mains
adaptor and 12 months guatamee

OTHER CHESS COMPUTERS IN OUR RANGE INCLUDE
CHESS CHAMPION — 6 LEVELS £47.39 + VAT
CHESS CHALLENGER — 10 LEVELS — £138.70

+ VAT.

BORIS — MULTI-LEVEL TALKING OISPLAY £163.64
+ VAT.

DRAUGHTS COMPUTERS

CHECKER CHALLENGER 2 LEVELS £43.00+ VAT.
4 LEVELS £78.00+ VAT.

The draughts computer enables you 10 sharpen your skills,
improve your game, and play whenever you want. The
computer incorporates a sophisticated, reliable, decisian
making fmuctoprocessor as ns brain Its high level ol
thinking ability enables it 10 respond with its best counter
moves hike a skilled human opponent You can select
offence or detence and change playing difficulty fevels at
any time. Positons can be verted by compuier menicry
tecall. Machme does nal permit Hegal moves and can salve
set problems Cumputer comes complete with insiructons,
Mains. adaparor and twelve months guatantee.

FOR FREE BROCHURES — SEND SA. E

ELECTRONIC CHESS BOARO TUTOR £17.17 inc. VAT.

A special bulk purchase of these amazing chess teaching
machines enables us to offer then: at only £19 75 less than
half recommended retail price, The electrantc chess tutor s
@ simple battery operated machine thai can actually teach
anyone to play chess and improve ther game nght up to
champuonship tevel This machine is not only for total
beginners but also for established players wanung to play
better chess. Unt comtams the electronic chessboard with
32 chess pieces, a 64 page explanatory bookler and a set of
32 progressive programme cards includmg 6 begmnners
cards, 16 check mate positions, 9 muniature games, 5
openings, 3 end games, 28 chess problems and 2 master
ganies.

PLAY ORAUGHTS/CHECKERS AGAINST THE COMPUTER

For FREE llusieaied brochures and rewews on TV and chess ganies please send a slaniped addressed envelope, and stale
which particular games you fequire informatian on
Callers welcame at cur shop in Welling - demonstratians daily - open trom Sar 5 3Upm Mun Sat (Sani lpm Wedl
To order by lelephone please quale your namie, address and Access/Barciaycard number
Postage and Packing FREE

AJD DIRECT SUPPLIES LIMITED, Dept. P.C.12 102 Bellegrove Road,
Welling Kent DA16 30D. Tel: 01-303 9145 (Day) 01-850 8652 {Evenings}

SOFTWARE

Get the best VALUE from your system.

EXPAND beyond the constraints of your standard
packages.

We undertake system design and programming for
microcomputers, for all types of business use.

Send us a brief description of your requirements and
be agreeably surprised by our estimate.

TAILOR MADE SOFTWARE NEEDS NOT
BE AT SAVILLE ROW PRICES

Rogis Systems Ltd

Keeper’s Lodge
Frittenden
Cranbrook

Kent
Tel: Frittenden (058 080) 310

Self contained

MONITOR

self contained FQ”

MONITOR

e@ Compact size, 5” x 7”
e@ Complete with power and

® Totally enclosed
@ All transisterised

@ Suitable for analogue
signals or alphanumerics

@ Operable on 220v Mains
or 12v DC power

@ Comparable to

video plugs, plus leads

@ Scan coil assembly
as standard supplied

@ 15v Mains or 12v OC power wire frame monitors
@ Ideal for D.E.M. use

ONLY £35.50 ONLY £85.00

EX VAT AND P&P

Croiton Electronics

Crofton Electronics Limited, 35 Grosvenor Road,
Twickenham, Middlesex. Tel.: 01 891 1923

XITAN SYSTEMS

CROMEMCO SYSTEM 3 — The ‘Rolls Royce’

£4,054.00 for this system with vdu.

The ideal business system. System includes a full 64K fast
RAM, dual full-size floppies (Persci 277), RS232
interface/20mamp loop for console device, parallel printer
port (Centronics/ Anadex compatible), 21 slots for
expansion, Lear Siesler 24 lines or 80 chars vdu, and...
CROMEMCO's CDOS operating system with their 14 digit
BCD extended disk Basic — ideal for those accurate large
numbers required by successful businesses. CDOS is
CP/M functionally equivalent, with many extra facilities.
Optional extras from Xitan include Fortran, Cobol, Text
Formatting, Z-80 macro-relocating assembler and DBMS at
£59.00 each,-CIS interactive screen handling Cobol at
£425.00 (recommended to serious business users),
Cromemco $100 boards, CP/M (we are an authorised oem

distributor of Digital Research’s CP/M) for the System 3,

Wordmaster, Wordstar, Supersort, and CPM374xX utilities.

COMING SOON! ... Full 7-terminal multi-user operating system from Cromemco for System 3 users. Up to 48K per user, all running
independently. This operating system has to be seen to be believed. it will run any of the Cromemco provided and supported software
packages, in any combination. Features include partition rescue facilities, allocating more memory to users, real-time clock for time/date
stamping of jobs and disk queueing techniques. Buy your System 3 now, expand later as you need it.

$100 BRITISH COLOUR BOARD

We are proud to offer the first BRITISH S100 Colour board. Manufactured by a local Southampton company — Hi-tech, we can thoroughly
recommend this product. Features include true PAL colour generation for high-definition on your television or colour monitor, 15+ colours
and black/white with 6 additional grey scales, 24 lines with 40 characters per line, with standard character set plus 44 numbers and symbols,
and 64 computer selected graphics symbols. Symbols include fractions and the £ symbol. Plotting is available at 80 x 72 resolution. Single
or double-height characters, with flashing on an on/off duty cycle of 3-1. The board is memory mapped on any 2K boundary, with its I/O
port set at any’of the 256 available on the S100 bus. Just plug into your S100 system and colour television and go! Driver software and
documentation provided. Price £295.00 ex vat cash with order. Please specify if for television or 75 ohm monitor.

ON DEMO NOW!
THE CROMEMCO 22-H

For only £4,995.00 set the reliability and quality of
Cromemco, coupled with the capacity of the new IM! 11

H ; megabyte hard disk drive. This is incredible value for
Z-2 money. Specification includes transfer rates of up to 10
Computer, fystem_” times faster than the fastest standard floppy disk, DMA

far ~ controller for up to 7 hard disk units, and the new extended

CDOS operating system. Systems available in three
configurations: — A) The Z2-H complete integral system,
64K RAM, Z80A cpu, two double-sided mini-floppies,
RS232 console port, parallel printer port, power supplies,
cables, case and 12-slot $100 motherboard (7 slots free). B)
Additional hard disk subsystem for existing system 2 or
system 3 users consisting of one hard disk, DMA controller,
power supply, case and cable. C) As unit B but with two
hard disks. Prices: Unit A) £5,380.00.

B) £4,330.00.

C) £7,420.00.

Xitan Systems also supplies and stocks vdus, printers, NORTH STAR HORIZON computers, Commodore Business Machines PETs, $100
boards, and books. We are here to demonstrate the range of quality microcomputer systems available for use today. Ring up for an
appointment now! You'll not be disappointed. We have Osborne’s Sales Ledger and Payable Ledger in source form for use on Cromemco
System 3 with CBASIC2, and we can offer a customising service on these programs. Additional software includes Microsoft Basic
Interpreter and Compilers, Cbasic, Macro80, and CP/M for the North Star Horizon.

Xitan Systems Ltd., 23 Cumberland Place, Southampton SO1 2BB.
Tel: (0703) 38740 Hours Tue-Sat 9.30 am to 5.30 pm

TECHNICIANS BE ONE OF THE FIRST TO OWN
SERVICE CASES | |The New Sharp MZ80-K

Sharp dealers for N.W. Kent.
Demonstrations given, at your premises, in
that area.

Other demonstrations by arrangement.

PET HIRE
From £5 per day or £25 per week.

Authorised PETSOFT/PETACT dealers.
10% discount on all Petsoft/Petact products.
Please add 50p p. & p. to your order.
Send large SAE for Petsoft catalogues.

FIVE excitInc TYPES AVAILABLE NOW

TOOL KITS TO YOUR SPECIFICATION All prices subject to VAT.
OR CASES CAN BE SUPPLIED WITHOUT Send Cheque/P. 0. with orders to:
TOOLS
Full Details From: ESSEX COMPUTER SERVICES

A. MILLS (ACTON) LIMITED 10 Grafton Road, Canvey Island,
_ CHURCHFIELD ROAD, ACTON, LONDON W3 6ED Essex, SS8 7BT.

anal lo a 4835/7, 01-993 2241/7 Telex 24224-305 Tel. Canvey Island (03743) 61663

¢ Circle No. 150 ¢ Circle No. 151

“New Bear Components E>

- |Leek it’s true

Bearbag 1 77-68CPUKIT .. . . £35.00
Bearbag 5 77-68 4K RAMKIT . . £55.00
Bearbag 6 77-68 MON1KIT . . . £37.50
Bearbag 12 77-68 V.D.U. KIT . . . £42.50
Bearbag 13 77-68 MON2 KIT . . . £47.50

Bearbag 16 77-68 EPROM BOARD
Ki ee eee 21.50

Bearbag 17 77-68 PIO BOARD KIT . £40.00

Bearbag 23 77-68 32K DYNARAM
Rll” foe & ceet7/5:50

Send for our complete Catalogue and Booklist.

CALLERS ONLY: 220-222 Stockport Road, Cheadle Heath, Stockport Tel: 061 491 2290

e Circle No. 152
34 PRACTICAL COMPUTING January 1980

Specification

The Acorn consists of two
single Eurocards.

1. MPU card

6502 microprocessor
512 x 8 ACORN monitor
1Kx8RAM

16-way !/O with 128 bytes
of RAM

1 MHz crystal

5 V regulator, sockets for
2K EPROM and second
RAM I/O chip.

2. Keyboard card

25 click-keys (16 hex, 9
control)

8 digit, 7 segment display
CUTS standard crystal
controlled tape interface
circuitry.

Keyboard instructions:
Memory Inspect/Change
(remembers last address

The Perfect Lead...
Acorn Microcomputer

Price £65 plus VAT in kit form

This compact stand-alone microcomputer is based
on.standard Eurocard modules, and employs the

highly popular 6502 MPU (as used in APPLE, PET; at ee
KIM, etc). Throughout, the design philosophy has palate elieaieg
been to provide full expandability, versatility and Steoping down through
economy. memory

Set orclear break point
Restore from break

Load from tape

Store on tape

Go (recalls last address
used)

Reset

Monitor features

System program

Set of sub-routines for use
in programming

Powerful de-bugging facility
displays all internal registers
Tape load and store
routines

Applications

Asa self teaching tool for
beginners to computing.

As alow cost 6502 devel-
opment system for industry.
As a basis for a powerful
microcomputer in its ex-
panded form.

As a control system for elec-
tronics engineers.

As a data acquisition system
for laboratories.

START WITH SYSTEM 1 AND CONTINUE AS AND WHEN YOU LIKE

the CPU card of System 1, it allows for up to 4% k EPROM,
1% k RAM and 32 t/O lines. tt has on board 5 V regulator
and optional crystal control. Custom programs may be
developed on System 1 and the card makes an ideal
dedicated hardware module.

Acorn Controller
£35 plus VAT (min config.)

Acorn Memory 8 k A fully buffered memory card allowing up to 8 k RAM

£95 plus VAT (kit form) plus 8 k EPROM on one eurocard, in an Acorn system
both BASIC and DOS may be contained in this module.
Static RAM (2114) is used and the card may be wired into
other systems.

Acorn VDU A memory mapped seven colour VDU interface with

£88 plus VAT (kit form) adjustable screen format. Full upper and lower ascii and
teletext graphics are features of this module which along
with programmable cursor, light pen, hardware scroll etc.,

make this the most advanced interface in its class.

Acorn Software Acorn BASIC — avery fast integer BASIC in 4 k

in ROM Acorn COS — a sophisticated cassette operating system
with load and save and keyboard and
VDU routines in 2 k
Agora Compaen: Lea. Acorn DOS — acomprehensive disc operating system in

4A Market Hill, Cambridge, Cambs.

Cambridge (0223) 312772. 4k

F Order Form
Please send me the following:
| [) (qty) Acorn Microcomputer kit @ £65 plus £9.75 VAT.
| (_] (qty) Acorn Memory kit @ £95 plus £14.25 VAT.
LJ] (qty) Acorn VDU kit @ £88 plus £13.20 VAT.
(_] (qty) Acorn Power Supply (for System 1 only) @ £5.95 plus
| £0.89 VAT.
[_] (Qty) Acorn Microcomputer assembled and tested @ £79
plus £11.85 VAT.
| [_] (qty) Acorn VDU assembled and
tested @ £98 plus £14.70 VAT.

Post and packing free on all orders.

Tenclose a cheque for£ .....
(indicate total amount) made out to Acorn Computers Ltd.

Please send me further details of this and other Acorn options |
Name |
Address |

COMPUTER

Acorn Computers Ltd. 4A Market Hill, Cambridge, Cambs. (0223) 312772. Regd. No. 140381

en ee ne ere ee

e Circle No. 153
PRACTICAL COMPUTING January 1980 35

Sane -ane

D.C. POWER SUPPLIES

Now, like Intel, Motorola and National you can buy
Power-One open frame power supplies and enjoy
quality and reliability at LOW LOW prices. Over 70
different models to choose from.

Floppy Disc Drive Supplies Single Output

— with connectors and.cables 5Vat2.7Aw/OVP £19.50
' for Shugart drives if required. 5Vat5.4Aw/OVP = £41.50
CP-249 — drives one mini 12V at6A £67.50
drive £33.00 15Vat5.4A £67.50
CP-323 — drives two mini
drives £60.00 Dual Output
CP-205 — drives one Shugart +*12to15Vat1.5A £41.00
SA800 or equivalent 8” drive +18to24Vat0.4A £32.50
£56.00 +5Vat5.4Aw/OVP £78.00
CP-206 — drives two SA800

£76.00

Tripte Output

5V, 9-15V, -5, -12, -15V at
1.8A to 10.8A From £41.00
to £137.00

SPECIAL* Beat this for value. TRS-80 compatible
floppy disk kits — including Shugart SA 400 drive
power supply and all cables. Single drive kit £263.
Dual drive kit £494.

HAL

COMPUTERS LTD.,

133 Woodham Lane, New Haw, Weybridge, Surrey
KT15 3NJ Byfleet (09323) 45421 (Code from London 91).

e Circle No. 154

@ BASIC BOOKS

Beginning Basic .
Introduction to Basic
Some Common Basic Programmes
Illustrated Basic . ms
Learning Basic Fast .
The Basic Workshop
Discovering Basic .
The User’s Guide to North |

Star Basic. :
Basic with Business Applications .
Basic and the Personal Computer .

A Guided Tour of Computer
Programming in Basic

Basic Basic

Advanced Basic .

PASCAL

Pascal: User Manual & Report .
Problem. Solving Using Pascal .
Programming in Pascal . .

A Practical Introduction to Pascal
An Introduction to Programming &
Problem Solving with Pascal

Introduction to Pascal . :

COBOL.

Cobol Programming
Learning Cobol Fast
Cobol with Style

“INSTANT DESPATCH SERVICE”

P. E. Gosling .
P. J. Hartley .
A. Osbourne .
Alcock

De Rossi .

K. Schoman Jnr.

R. E. Smith

R. Rogers

Hayden

Dwyer &
Critchfield

Dwyer/Kaurman
J. S. Coan
J. S. Coan

Springer-Verlag .
Springer-Verlag .

P. Grogono
A. Addyman .

Schneider
Welsh .

Nickerson
De Rossi .
Hayden

=
SUD a ety AC

trp tr In th Ih th In In
Ad ONoON POW
Ao COCOMnNnn

thir tn th tn tn

tr tr tn

SLOUGH MICROSHOP

We stock:

Commodore PET
Exidy Sorcerer
North Star Horizon

Full demonstration equipment available
now.

Extra services include:

A complete hardware maintenance
service

A software service; tailor-made
or packaged software available

Callin at our showroom

120 High Street,
Slough, Berkshire

Tel: Slough 22855/72470

° Circle No. 155

FORTRAN
Elementary Computer. cui
Fortran 1V 2 8 ESDe

PROGRAMMING

Intro. to TRS80 Graphics . :

Design of Well Structured Programs

Chemistry with a Computer

Top-Down Structured so
Techniques

Computer Input Design|

Compt -r Output Design

GAMES
32 Basic Programs for the PET COMPUTER
101 Basic Computer Games
Games, Trick & Puzzles for a
Hand Calculator .
Games with a Pocket Calculator
Star Ship Simulation .
Game Playing with Basic
Game Playing with Computers
Game Playing with Basic . .
SARGON-A Chess Computer Program
in Z80 Assembly Language
Chess & Computers . ;
Chess Skill in Man & Machine a
57 Practical Games & ey
in Basic

Lic)
cy
(ec
i=]

Bogu:!ausky

Inman
Alagic .
“auchon .

ke tintin

—

McGowan
Woolridge
Woolridge

W. Judd

Onw own

=
URS BS pee pgs) 2

v. Sper ncer

—oO NN ENP TO

D. Levy
P. Frey

Bao ooo

—
Qo

£
£
£
£
£
£
£
£
£
£
£
£
£
£

er
es
°

SEND FOR FULL BOOKLIST
CREDIT SALES (Minimum £10), Access and Barclaycard
Welcome.

CALLERS AND MAIL ORDER: 40 Bartholomew Street, Newbury, Berks. Tel: 0635 30505
CALLERS ONLY: 220-222 Stockport Road, Cheadle Heath, Stockport Tel: 061 491 2290

® Circle No. 156
PRACTICAL COMPUTING January 1980

TMZ80 from TERODEC

The TMZ-80 range of microcomputer systems provide cost effective
and reliable solutions to your business problems with unrivalled flexibility

@ Choice of operating system — CPM1.4, CPM2.0, or OASIS

@ Interfaces to most VDU’s, Line, Dotmatrix, Daisy Wheel Printers and Modems

@ 64K Byktes of RAM as standard — expandable to 256K Bytes (for multiuser environment)
@ Single or Multiprocessor @ Installation and Commissioning

@ 1-4 m Bytes Floppy Disc storage B Attractively styled work station

@ Hard, Fixed or Cartridge Disc expansion w Comprehensive standard software available
@ Custom Software service @ BASIC, CBASIC-2, FORTRAN, ANSI 74 COBOL
@ Single or Multiuser B® and PASCAL

@ Software Hot Line B Full range of VDUs and Printers

@ Reliable

@ Nationwide maintenance

@ 4 MHz Z-80 CPU

B Staff Training

TMZ-80/1 1M Byte, 64K with VDU and Workstation £3995
TMz2Z-80/2 2M Byte, 64K with VDU and Workstation £4295
TMZ-80/4 4M Byte, 64K with VDU and Workstation £5495

TERODEC are the sole U.K. Distributor for DELTA PRODUCTS, CENTRAL DATA
CORPORATION and Distributors for MICROMATION. We supply a complete range

of Hardware and Software that represent the best in quality, price and delivery. Our

product range includes: S-100 computers from DELTA, MICROMATION and

CROMEMCO; S-100 Boards CPUs, Disk Controllers (Single and Double Density)

For all popular drives 8” and 5’, Dynamic CDC RAM, Static RAM and Interfaces;

Add on Single and Double Density Disk Drives for TRS-80, Exidy Sorcerer and all

S-100 Computers; Printers from DECISION DATA and PRINTERM; VDUs from TVI, SOROC and
PERICOM; A comprehensive range of applications software, Accountancy, Stock Control, Word
Processing and more; Compilers; Interpreters; Assemblers. When other products do not measure up
callany TERODEC Showroom or Dealer for fast response.

MICROBITS OEM and Dealer Enquiries Invited
34B London Rd., Blackwater,

suncurcta Camberley, Surrey TE RO D EC

a ee (MICROSYSTEMS) Limited
TERODEC SYSTEMS LTD ia

16/17 College Place, 43 Qualitas, Roman Hill
Southampton, Hants. Bracknell, Berkshire
Tel: (0703) 39511/5 RG12 40G

® Circle No. 157
PRACTICAL COMPUTING January 7980 37

THE SATELLITE VIDEO
KEYBOARD TERMINAL

e GIVES YOU
. MORE ON
ee YOUR SCREEN

(INCLUDING 128 GRAPHICS CHARACTERS).

The Satellite is based on the KTM Keyboards made by Synertek. The on-
board microprocessor gives full control over the display allowing not only
the full ASC11 character set to be displayed, but also 64 graphics
characters which, with reverse video becomes 128.

An auxilliary serial port allows onward transmission to or from a remote
peripheral such as a printer, or modem, and may be switched on and off
under soft-ware control.

The Satellite comes built and tested. All you need is a monitor (a
television and modular may be used with the Satellite 1) and a 5V 1.25A
power supply. If RS232 is to be used, then +12 at 100mA is also
required, ee

SATELLITE 1 24 rows of 40 characters £215+ VAT.

SATELLITE 2 24 rows of 80 characters £250 + VAT.

(Dealer Enquiries Welcome).

SPECIFICATION.

*“ 24 rows of 40 or 80 characters.
* Full 128 ASC11 Character Set.
PLUS 128 graphics characters.
* Full RS232 or TTL Serial * Switch selectable European/
Interface with RS232 handshaking. USA standard.
INTERACTIVE DATA SYSTEMS 14, BUCKMAN CLOSE,
GREENLEYS—MILTON KEYNES. Telephone: (0908) 313997.

* Auxiliary RS232/TTL Serial
Port for printer, modem, etc.

* |nterlace/non-interlace.

* Line truncate/non-truncate.

* Direct cursor addressing.

¢ Circle No. 159

OMPUTER
SERVICES

NORTHSTAR EXPERTS
IN THE NORTH-WEST

HARDWARE

STATIC RAM & 2 DOUBLE

DENSITY DISK DRIVES

Both include North Star DOS & BASIC software

WITH 32K £2068
OR 48K £2400

(Extra paper tape uutilities,add £5)
Cursor controlied TEXT EDITOR
CP/M BASIC (Microsoft Version 5
FORTRAN COMPILER
TRUE BASIC COMPILER
North Star PASCAL which requires 48K
BASEX COMPILER with disk handler
Interactive WORD PROCESSOR
TINY PASCAL COMPILER including
source written in PASCAL
8080 Assembler
Sample programs are available on disk for
all the above languages Add

GRAMA WINTER Business Software on NorthStar
AND CORAL 66 under CP/M ENQUIRE for details

Educational Discounts Available 48 Lomond Ave
Prices are Exclusive of Blackpool FY89NB
VAT & CARRIAGE 0253 692954

Interpreter)

® Circle No. 158

® Circle No. 160

PRACTICAL COMPUTING January 1980

BIRMINGHAM = “ruter

CEFCU: DETUEUTOR COMMODORE PROFESSIONAL SYSTEMS
2001 — 8K
All Models Now
Ex-Stock
3040 Dual Floppy
3022 Tractor Printer KIM-1 — Motherboards
Etc.

FI AL eee ee
DISTRIBUTOR 3 EUROAPPLE Il NEW LOW PRICE #€

Lr Apple ll16K B.W. £750 Barrels of Software
‘ Apple ll16K Colour £819 including
‘ . Apple || 32K B.W. £819 Word Processor
Apple !132K Colour £888 Sales Ledger
a Apple ii 48K B.W. £888 Management Information
Apple {148K Colour £957 Stock Control
Etc!

PROFESSIONAL SoS EES
tbl bic 34 BUSINESS PROGRAMS EX-STOCK 3#
Commodore BS1000 Assembler. L.S.P. Business information. Stock control word
processor

Gramma (Winter) Complete Business package

Petact Sales — Purchase — inclusing stock control, payroll

Computastore Comprehensive payroll system

Trader _ Interactive invoicing and stock control

eg 3 NEW MODELS NOW AVAILABLE 3#*

MAIN AGENTS Fast, efficient, reliable business printer
: a —— & Tractor feed — 120 CPS bi-directional
a a Parallel and serial inputs standard
ee es Full upper and lower case
900 CH-buffer standard expandable to 3K

Compatible with most systems including
Pet — Apple — TRS-80 — Sorcerer — Etc.

* Largest selection of micro-books in the Midlands *
%* Magazines — programming aids — PSU Monitors * m
*Petsoft programs — Games galore — Full range stocked * me
Pet dual “joy stick” with music box and demo tapes ‘Fantastic’x °
Own brand data tapes C15 — super quality — mini diskettes (boxed 10)*

*HP terms available from £100 deposit 12-24-36 months *

Camden Electronics Showrooms open
First Floor, # Sales Mon-Sat 9.30-6pm
ihe eg Road, * Service Programs demonstrated
mall heatn, * Satisfaction continuously daily
Birmingham B10 0UG Phone 021-773 8240

($s pe
EW.
¢t

PRACTICAL COMPUTING January 1980 39

West London’s Pet Specialists

@ Comprehensive advisory and
demonstration service before you buy.

@ Systems tailored to your requirements.

@Consultancy and maintenance service
after installation.

@ Business software including sales and
purchase ledger, stock control, invoicing,
payroll and data management.

@ Full range of peripherals including memory
expansion, floppy disks and printers.

@ Books, games and accessories.

@@mmme = Adda Computers Ltd.,
17/19 The Broadway
Ealing, London W5 2NH
(Between W.H. Smith and Burtons.)

mes = Telephone 01-579 5845
we add up toa great deal.

® Circle No. 162

Yo u e invited to come and see the

pt BUSINESS SYSTEMS

at your Official

commopore CX ana PetSott
dealers in... StocKton-on -Teeg

Combine the NEW large keyboard PET with the
ACT PETSOFT Professional Disk Systems and
Software, and the result is a powerful business
tool. If your application includes Sales Ledger,
Invoicing, Purchase Ledger, Payroll or Stock
Control, then come and see us without delay.

Intex (Datalog) Limited
Eaglescliffe Industrial Estate, Eaglescliffe
Stockton-on-Tees, Cleveland TS16 OPN England
Telephone Eaglescliffe 781193 (STD Code 0642)
Cables Intexrad, Stockton-on-Tees, Telex 58252

® Circle No. 163
PRACTICAL COMPUTING January 1980

DATRON of SHEFFIELD

SHARP MZ- 80K
Home Computer

See it inoperation
and buy it at DATRON

Demonstrations.
Qam-5pm Monday-Saturday.

Callanytime -no obligation -
or by mailorder.

Delivery free anywhere inthe U.K.

BOOKS from DATRON

all books in stock at press date

The BASIC Handbook David Lien £11.50 PET Work Books Vol. 1-5 £15.75
lllustrating BASIC Donald Alcock £2.25 PET Work Books Vol. 6 £3.25
Basic BASIC Donald M. Munro = £2.00 Intro. to Personal & Business Computing Zaks £4.95
The Little Book of BASIC Style Nevison £5.25 Micro Appl. in Business & Industry Whitbread £9.50
Some Common Basic Programs Osborne £6.45 Peanut Butter & Jelly Guide to Micros Willis £6.20
Some Common Basic Programs (PET cassette} £7.95 Running Wild Osborne £2.95
32 BASIC Programs for the PET Rugg & Feldman £9.75 A Career in Computing Penney £3.50
BASIC Primer Waite & Pardee £6.95 Philips Guide to Bus. Computers & the
A guide to BASIC Programming Spencer £8.85 Hectronic Office Enticknap £3.50
A quide to PL/M Programming McCracken £7.95 ‘
Basic Computer Games Creative Computing £5.50
PASCAL An Intro. to Methodical Prog. Findlay & Watt £4.95 More Basic Computer Games Creative Computing £5.50
Introduction to PASCAL Welsh & Eider £5.95 Game Playing with Computers Spencer £10.20
Programming in PASCAL Grogono £6.75 Game Playing with BASIC Spencer £5.50
Primer on PASCAL Conway et al £7.10
Struct. Prog. & Problem Solving with How to Build a Working Digital Computer Alcosser et al £4.60
PASCAL Kieburtz £8.40 How to Build a Computer Controlled Robot Loofbourrow £5.95
Micro Problem Solving — PASCAL Bowles £6.95 How to Profit from your Personal Computer T. G. Lewis £5.50
COBOL for Business Applications Philippakis £10.25 TTL Cookbook Lancaster £7.15
COBOL with Style Chmura & Ledgard £5.40 CMOS Cookbook Lancaster £7.50
Learning COBDL Fast de Rossi £6.45 TV Typewriter Cookbook Lancaster £7.25
Cheap Video Cookbook Lancaster £4.95
FORTRAN Techniques A. Colin Day £2.25
FORTRAN Fundamentals J. Staingraber £3.45 Best of Byte ; £8.45
Problem Solving & Struct. Prog. in FORTRAN — Friedman & Best of Creative Computing Vol. 1 £6.95
Koffman £9.95 Best of Creative Computing Vol. 2 £6.95
Computing with FORTRAN Donald M. Munro = £3.95
An Intro. to Prog. & Applications with me Gwe Gee ee eee ees ee ee ee
FORTRAN Hull & Day £8.45 r "Phone in your Access Send s.a.e. for full list. Prices correct at

Barclaycard No going to press. Add 12p insurance on

Z80 Micro Handbook W. Barden £6.95 | 0742 585490 books if required.

780 Programming for Logic Design Osborne £6.30 or complete this fail (eGR (GEESE Ce
280 Micro. Prog. & interfacing Bk. 1 Nichols & Rony £7.75 l ae Vee TEXAS INSTRUMENTS == nascom=" I
Z80 Micro. Prog. & Interfacing Bk. 2 Nichols & Rony £8.50 j Picese sieht = i
6502 Assembly language Prog. Leventhal £6.95 j ienaiéce- ie I
6502 Applications Book Sybex £8.95 Cheque/Postal Order No.

Programming the 6502 Zaks £7.95 i Barclaycard/Access No. |
Programming a Micro (6502) Foster £7.25 Name

P&P free U.K. Le I
Overseas add£1 any order size I Datron Micro Centre, Latham House, 243 London Road,

° Circle No. 164
PRACTICAL COMPUTING January 1980 41

115-117 WANDSWORTH HIGH STREET
LONDON SwW18, ENGLAND

Telephone: 01-870 4805

Telex: 8813089 INTPRM G

Teletype 43 TRS-80 micro floppy disk system

New Low Price £775. ....:. price £290 .......«

True 30 cps Data Printer Applications Capacity up to 250,000 bytes per side of diskette Based upon the Pertec FD200 Microfloppy Disk

H ; ; (double density) Drive, the unit is directly interface compatible with
Versatility, reliability and economy are key points % time sharing the Schugart Model SA400 disk drive and has been
already established by Teletype *® and their range

% input/output Housed in a smart black case the unit will stand fully proven by the Tandy Corporation on the
of terminal products. The Model 43 enhances the ; ‘ adjacent to the computer and is completely self TRS 80 micro-processor. ;
range by offering a true 30 cps serial % point-to-point data contained with internal power supply and simple user For multiple drives on one computer, upto four units
asynchronous keyboard printer ideal for a wide communications interface. can be driven in a daisy-chain fashion. An LED
y atte % OEM systems indicator shows which unit has been selected by the
range of applications. Tee
¢ Circle No. 165

RESEARCH RESOURCES LTD.

You are already out of date —
2nd generation micro-computers are here.

Two expandable computer systems: 32-56K RAM, 128-768K RAM

6809 16/8 bit processor — more than twice as powerful as 8080/Z80

Three disc systems — 170k, 2.5 Megabyte and 64 Megabyte

FLEX operating system (50 much better than CP/M)

Both Multi-user and Multi-tasking/Multi-user operating systems
Scientific Basic and Business BASIC, PASCAL, PILOT, Macro-Assembler, Editor, Debug plus BASIC pre-
compiler available. FORTRAN soon

Write or phone for full information and demonstrations of the entire range of 6809 computer systems:

Research Resources Ltd
40 Stonehills, Welwyn Garden City, Herts.
Tel. Welwyn Garden City (07073) 26633 (24 hours)

PRACTICAL COMPUTING January 1980

H1400 VDU

Low Cost
Video Terminal

£550

New low cost VOU featuring full cursor controls
and 24x80 screen displaying highresolution
upper case characters using a 5x7 dot matrix.
Keyboard generates all 128 ASCII codes and
unit interfaces through an RS23?2 interface at
transmissionrates upto 9600 baud

H1500 series features upper and lower case
charactersusing7/ x9dot matrix integralnumeric
keypad. buffered editing, and printer port.

DECWRITERS

Keyboard Printers

From £850

¢ Circle No. 168

Industry standard dot matrix keyboard printers
featuring 132 column upper and lower case
printing on standard iisting paper at printing
speeds of continuous 30cps or 180cps KSR and
RO versions availabte with a wide range of
optional features

MICRODISC

Minidisc Storage

File oriented mass data storage minidisc
terminalfeaturingrandom access by filename
to 200,000 characters stored per diskette.
interfacing through terminal and modem/CPU

e
Terminal RS232 interfaces at up to 9600 baud. Powerful
£950 string search and editing options.
¢ Circle No. 169
HYTE RM Range of microprocessor controlled ‘daisy-
wheel terminals for text processing
H lications, printing at 45cps over 158 columns
xt Printer OS alll

e t P I te with a wide range of interchangeable type

Terminals fonts. Many advanced features including

From £1900

1BM2741 compatibility, graphics capability,
‘absolute’ tabbing, and variable character/line
spacing.

PRACTICAL COMPUTING January 1980

DATACASSETTE

Cassette Storage
Terminal

£750

® Circle No. 171

LX100 SERIES
Desk Top
Printers

From £1000

Magnetic tape cassette unit storing 150.000
characters per Cassette, communicating atup
to 2400 baud throughterminal and modem/CPU
RS232 interfaces with full localandremote
device control, ECMA, Tland NCR format
compatibility options available.

New low costrange of desktop Serial printers,
printing over 80 or 132 columns at 100 or 180cps
on standard listing paper using a7x7 or 7x9 dot
matrix. Options include VFU, second paperfeed
mechanism, 9x9 matrix with italic or expanded
printing, buffed serial RS232 interface.

RAIR 30-32 Neal Street, LondonWC2H 9PS_ Telephone 01-836 4663

Stop puzzling over the

Micro Jigsaw and buy

an operational system
fo fit your needs

If only buying a microcomputer system was as
simple as using one.

Just look at the advertisements in this
magazine. When can you find time to digest
them all?

There are millions of chips, thousands of
boards and hundreds of peripherals, software
systems and application packages. How do you
pick the right ones to meet your requirements?

And put them together? And make them work?
And add the specials you want?

At Digitus we have computer professionals
working full-time putting systems together.
Absorbing information. Testing equipment and
software. Writing programs. Training users.

At one stop you can commission acomplete
system to fit your requirements.

Last year we supplied systems for: number
processing, word processing, data processing,

graphics and machine control. Advised
accountants, surveyors, archaeologists and
engineers. Helped DP departments and smal
business men. Developed software for personnel,
incomplete records, order processing, business
games, linear programming, process control and
terminal emulation. And were retained by other
computer companies to advise on micros.

This year we can put even more experience to
work so that you can benefit from micro technology
...in comfort.

Come and see us. Spend a few hours
discussing your requirements. Attend a training
course. Select a machine. Test drive some
software.

Solve the micro puzzle. Buy an operational
system that fits your needs.

Call for an appointment with one of our
consultants.

—

Digitus Limited Microtechnology Centre Dumbarton House 68 Oxford Street

London W171 Tel: 01-6360105

® Circle No. 173

PRACTICAL COMPUTING January 1980

a ee ee er errs |) oc al
What happens next?

IT IS NO SECRET that we live in stirring times and that, indeed, THIS IS A FAR CRY from the state of affairs a couple of years

many citizens do not know but that each moment may be their
next. This particularly applies to Practical Computing which is
proud to hold the banner in the vanguard of the wonderchip
revolution.

INDEED, TIMES ARE SO STIRRING that the future often
seems to e rushing on the present at such a pace that one is
almost afraid to look out of the window for fear that every-
thing will have rearranged itself indoors while the eyes were
off it. Well, that was the case a few months ago. Recently the
Pace seems to have abated; but it is, on the micro scene, merely
holding its breath. Great things are going to happen again soon.

WHAT ARE THEY? One can see three. The first is affordable

ago. Then the world was electrified by the news that for a
couple of hundred pounds you could have a real computer on
your dining table. Well, we’ve been through that stage, and
now we tell each other: ‘For £3000 you can have a Serious
computer on your dining table’. In two years’ time we'll be
saying: ‘For £6000 ...’

IT IS INCREASINGLY OBVIOUS that the micro market is

repeating history. We are going through exactly the same stages
as users of big machines in the last ten, fifteen years. At first,
anything is wonderful. Then we want more store, more speed,
and we’ll pay ten times more. Then we’re offered much more
store, much more speed and we’ll pay — not much, but some
more again. But the same rule applies: you never pay less than
you paid last time, and usually you pay more.

8in (or perhaps smaller) hard discs. As Mike Gardner told us in WHAT WILL THIS DO to the market place? Projections from

the December issue, the hard disc is here — at least for Apple
users — and soon it will be available for most micros. This will
make a huge difference. At last we will have more backing
store than can be filled in any reasonable time (it would take
three weeks’ non-stop typing to fill the Corvus’s 9.5MB). Huge
capacity coupled with 10 times faster access makes all sorts of
programs practicable that weren’t before. Emphasis will shift
perhaps from subtle programs to operate on minimal inform-
ation, to manipulation of useful masses of data.

THE SECOND INNOVATION will be, of course, 16-bit pro-

several sources are that there will be three million micro-
computers — mostly with discs of some sort — in the English
speaking world, with three hundred thousand in this country,
by 1983. The market will stratify, with clear divisions between
the cheap, ‘board’ computers, home systems (but see Andre
Souson’s reservations in the article ‘Upsetting the Applecart’,
this issue) and ‘small business systems’ which will actually be
minis by today’s standards. However you slice it, the micro-
computer in some for will become as familiar a feature of
middle-class professional life as the typewriter, hi-fi or motor-
car are today.

cessors, and to go with them, the third innovation: 256KB of AUTHORS WILL USE THEM to write books. Archaeologists

RAM. People are talking of machines along these lines being
available in two years’ time and costing something like £6,000.
The 16-bit processor automatically gives twice the speed of an
8-bit machine, and the improved architecture of, say, the
Z8000, gives another factor of three to five. The effect will be
that the new ‘super-micros’ will work 10 times faster than
today’s, giving more processing power than most individual

will take them on digs to classify their finds. Yacht designers
will refine the lines of their boats on them; gamblers will use
them to beat the laws of chance. Children will learn French
and Chinese from them. We’ll have them in networks (see
February PC) and clumps and clusters. They’ll be so normal
we’ll hardly think about them.

users can absorb. Result: time sharing on half-a-dozen or so AND YET WHAT A STAGGERING MACHINE the micro-

work stations, giving for all intents and purposes the power of
today’s mini at £30,000 plus, for about a fifth the price.

WHAT IS LACKING from this attractive picture, of course, is
the software. There are, as yet, no time-sharing operating
systems for 16-bit machines. But they will come, given the
market.

computer is. Under the table in the hall of my house is a
machine with a million moving parts. I can rearrange them by
tapping a key, and already it is so commonplace, so ordinary a
feature of my life, I hardly think twice about it. Yet this
machine has so many possible conformations that if one were
examined every second, it would take longer than the life of the
universe to look at them all. The mind boggles. Where indeed,
is it all going? — Peter Laurie

Micro Mouse maze

TIME FOR an ongoing update
informational situation. The news
from this department is that we
have some 100 possible entries, all

of whom we should have had their
entries acknowledged long ago. In
the next issue we start an occa-
sional series on robotics which is
designed to be useful to
contestants. So far we have a few
offers of sponsorship. When there

PRACTICAL COMPUTING January 1980

are enough to be worth circulating,
we'll do it.

Several puzzled people have
queried the rules of the com-
petition (published in October
PC), which they say are too vague.
Ha! That was deliberate. When we
sat down to draft them, we came to
the conclusion that the object of
the competition is to get people to
produce interesting software.

Too precisely-defined rules —
and in particular, too precise a
specification for the maze itself —
would stifle ingenuity. So don’t
assume that the passages will be
precisely 6¥%2in wide, that the
angles will be precisely 90°, that
the maze will be exactly 14ft
square. Your mice must learn to
cope with life in the raw.

May the brightest mouse win!

Can you absorb
Micro Shock
and develop skills
in microcomputing?

Digitus receives... one new peripheral a week, a new software product a fortnight,
anew microcomputer a month. Mini-Winis have arrived and the new wave of 16 bit
micros are here. The next wave of developments will bring communications
processors, database machines and sophisticated digitizers.

That’s what we call ‘Micro Shock’! No sooner have you absorbed one wave than

the next comes crashing in.

We need people who can make sense of these developments: selecting the best
components, tailoring software and hardware, putting together operational systems,
in short, solving the micro puzzle for our customers.

Software Development

There are a wide range of languages, aids and utilities
that have to be put together and enhanced. People who
can both build systems software and evaluate new
products are required. Knowledge of available software
will be an advantage, together with system software
experience.

Communications Expertise

Flavour of 1980 will be tinking micros to minis and
mainframes, leading on to hooking micros into the
electronic office. This function will Involve consultancy
and development. A knowledge of communications is
essential, including protocols and emulators. A first
project will be to develop an ICL 7020 emulator.

Hardware Engineering

Building a work shop, assembling ready made
components, adding in specials, testing equipment,
involvement in control applications... these are some
of the elements. We need creative hardware engineers
who can also turn a hand to some assembler
programming.

Applications Development

There are a host of new applications on micros, as well
as variations on old themes. Time scale to
implementation is short, teams are one to three man
strong. Two days to evaluate a requirement, two weeks
to design, two months to implement is not unusual. We
need designers and programmers who can talk to users,
assimilate their requirements and produce operational
solutions.

Customer Support

Understanding applications, sizing systems, producing
outline designs, implementing programs and training
users ... these are a few of the elements involved in
customer support. We are looking for people who are
technically adept and have wide ranging knowledge and
interests. Our customers include dp departments,
architects, engineers, accountants, lawyers, surveyors
and other professionals.

Training

Digitus runs four levels of training course: micro impact
for senior dp executives; micro application for
management; basic programming for first time
programmers; micro software for programmers. We
need consultants who can run training courses as well
as participate in the other activities.

Digitus

Digitus is building a team of high calibre individuals
with complimentary skills who can undertake single and
multiple microcomputer projects. In 1979 the company
completed projects on: machine control; emulation,
linear programming; matching systems; personnel;
word processing and accounting on 8080, Z80, M6800,
6502 and Micro Nova processors.

We provide competitive salaries, profit sharing,
almost infinite job variety and stimulating colleagues to
work with. If you are ready to develop your career in
micros, forward a professional CV and call for an
appointment.

oes

AlanC. Wood Managing Director
Microtechnology Centre Dumbarton House 68 Oxford Street

Digitus Limited

London W1_ Tel: 01-636 0105

PRACTICAL COMPUTING January 1980

Surprising reliability

A SURPRISING fact is that the TRS-80
disks can be made to operate with near
100% reliability.

No software will operate if the hard-
ware or operating environment is suspect.
For serious users the following are essen-
tial:
¢ Filter all power leads
© Use the latest upgrade

— buffered expansion interface

— additional cable link

— modified Micropolis drive
¢ Don’t use cheap RAM — better to buy

as complete system
¢ Keep out dust and sticky fingers from

the drives and discs
¢ Use the latest release of DOS — 2.3 or

much better NEWDOS +
* Use a cooling fan — certainly for the

drives and possibly also for the key-

board.

Evaluate the consequences of using
non-standard parts, or purchasing from a
‘dealer’.as opposed to someone who can
offer a complete software/hardware back-
up. A good example of such pitfalls is
provided by an intrinsic error with all
versions of DOS. This manifests itself by
file I/O errors with sequential type file
writes as found in both Basic and the
Electric Pencil or anything else which uses
the same DOS routines. Even worse, these
errors may not be detected by the DOS
and appear to leave permanent parity
error glitches on ‘the discettes. Even
NEWDOS suffers from this bug.

A simple and reliable solution is
obtained via the Tandy hardware modific-
ation to the Micropolis disc drive.

With the correct approach, the TRS-80
should be-reliable all day and every day. If
you drop out of Basic, meet unexpected
syntax errors or meet disk I/O errors, then

OFO|O O}OMO OL je BSICio. olojo
x x Xx |X]
X|X| xX] 1% RITXIO XlOlx ~xXTO
1 2 3 4 5
Over: - O oO
xo. & x
JAX x|O X
6 1 | 8 9
0 X19 |X O|XIiX ololo
x x Xlo[xX °}0 0 _o|x|x ‘xlob¢
X1O|C O[X|P XII IX O1OI? xX/Ox
10 11 12 13 14

Reader Rowell’s 14 ‘winning’ positions in noughts and crosses.

it is a malfunction as opposed to any
design weakness.

NEWDOS represents a ‘better’ oper-
ating system — one example of its
advantages is that users of NEWDOS +
can use SUPERZAP (a Basic program
provided with NEWDOS+) to detect
parity error glitches (VERIFY DISK
SECTOR) and then repair the disc
(SCOPY after DD). Users of TANDY
DOS have had it. Moreover unlike
NEWDOS + users, they will not be able
to BACKUP the disc due to SOURCE
DISC READ ERRORS — those nasty
glitches once again.

Sequential files are by far the simplest

Clo oclo/o
X[X[o
OlIX Ol|X]x

PRACTICAL COMPUTING January 1980

Feedback gaa

Here are the winners of the Practical Computing Programmer of the Year award at the
recent prize-giving ceremony in London. From left to right: Mike Amode, Alan Baylis,
Georgina Jolliffe, judge Jim Woods, the Editor, Geoffrey Jolliffe, J). J. Walters. Not shown
is D. W. Conran, who was on an Army training course.

to program and for some data structures,
sequential techniques may represent the
most efficient use of disc space.

David Robbins

‘Winning’ positions

SINCE NO-ONE has commented on
Professor Michie’s article on Artificial
Intelligence, (Practical Computing,
September) may I say that his statement,
that Britain’s chances of leading in
robotics were wiped out when the Science
Research Council withdrew support for
his University’s project, is in very bad
taste.

First, because his group is by no means
the only one — there are. others at
Imperial & Queen Mary College, and at
ICL, to name but a few.

Second, because he can’t even play
noughts and crosses proficiently! There
are not 77 winning positions as he
maintains, but 91 (see below).

And if he can score less than 85% at
noughts and crosses, is he justified in
making snide cracks at chess Master
performance in the much more difficult
Queen vs. Rook ending?

Geoffrey M. Rowell,
London S.E.27

No doubt Professor Michie felt — and feels —
strongly about the abrupt cancellation of his
project ten years ago. Whether or not his
remarks are in ‘bad taste’, as Geoffrey Rowell
would have them, there is no doubt that
robotics in Britain took a blow from which
they have not yet recovered. If he doubts this,
how can he explain the leadership of the
Japanese and the Americans in a field which
largely began here?

As far as we can see, at least six of the
further 14 ‘winning’ positions in noughts and
crosses can only arise if play goes on after 0 has
won. — Editor.

DPS-1 MAINFRAME

Introducing the DPS-1 the full 1EEE $100 bus computer system from Ithaca
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FOR EDUCATION, tNDUSTRY, RESEARCH and ail professional uses, including
hardware and software development, low cost OEM systems, teaching applications
etc.

A MINI COMPUTER using MICRO technology at a ridiculous MICRO Price!!! The
front panel with a backplane and power supply accepts S100 bus boards from many
manufacturers.

SOFTWARE

for your S100 system
PASCALIZ The new language for Micros

CPIM Version £165.00 (5%” or 8”)
K2 Version £131.25 (8”)

Runs under K2 operating system.

* Compiler that produces Z80 macro assembler code
— NO NEED for slow run time P-code interpreter. »
Comes complete with Macro assember. * Produces
binary object modules — small and fast. * Modules are
re-entrant and can be put into ROM. » IMBED, TRACE
and ERROR debug facilities. * Recursion

K2 OPERATING SYSTEM = £56.25

8" disk based operating system — distributed on Shugart compatible 8” floppy disk
% TED — 52 command character orientated text editor with macros. * PIP — File
and directory handter. # ASMBLE — full 280 2 pass assembler. * HOT — Hex
debug tool. * QCIl — Utility overtayicommand decoder. * SYSGEN — System
builder. » COPY — disk to disk file copier. » DUP — disk duplicator.

OEM $100 boards

from the experts! Assembled

and tested
8K Static RAM board (450ns) £123.75
8K Static RAM board (250ns) £146.25
16K Static RAM board (450ns) £275.00
16K Static RAM board (250ns) £295.00
64K Dynamic RAM board (250ns) £615.00
Z80 cpu board (2MHz2)
280 cpu board (4MHz)
2708/2716 EPROM board
Prototype board (bare board}
Video display board (64x16,
12B8U/L Ascii) £108.75

AVAILABLE SOON: ZBC-1 Single board |
computer for OEM market. Available in
basic through to fully expanded. 4MHz
Z80A, 64K RAM, memory mapped 4K
screen buffer, composite video, up to
16K power on EPROM monitor, 4
parallel ports, 2 serial ports, 4 channel
counter timer. 1 off £895 — please
phone for a quote for your needs.
{quantity discounts available}.

products from :
. - Assembled
Ithaca audio! and tested

Disk controller (up to 4 single

or double sided drives) £131.25
V0 board (4 paratlel and 2 serial
ports) with Interrupts £210.00
0 board (4 parallel and 2 serial
ports) less interrupis £180.00
$100 front panel {as used

in DPS1) £245.00
Analogue I/O board £295.00
ALL MANUALS AVAILABLE SEPERATELY £2.50 each

DATAVIEW LTD. (Colchester) (0206) 78811

rHaca [JonforMsyss enous

(formerly ITHACA AUDIO of New York)

Unoterssysiennns

CONTACT THESE UK DEALERS
NEWBEAR COMPUTING STORE (Newbury) (0635) 30505 Telex: 848507
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CODIFIED COMPUTER SYSTEMS (North London) 01-226 131:
‘DATA SYSTEMS ENGINEERING (Fife, Scotland) (03374) 469
MICROPEOPLE (Nottingham) (06076) 69117

EUROPEAN SUBSIDIARY
58 Crouch Hall Road, London N8 8HG. England.
Telephone: 01-341 2447

Just look at these professional features!

* FRONT PANEL (we won't ask you to debug our hardware, but we will give you
the toots to debug yours!) Has lights and switches to allow inspection and control
of addresses and data. Other features include programmed input switches, and
output lights, Examine, Examine next, deposit, deposit next, single or slow step (0.1
to 1000 PS), hardware breakpoint on any data or address byte, repeat instruction
and many other hardware diagnostic facilities.

* 30Amp. 8V power supply, 5 Amps on + 16v fails (all rails are seperately fused)

* 20 slot IEEE S100 Motherboard with active termination and shietding between
bus lines

* Guaranteed operation at 4MHz.

The DPS1 comes as a mainframe with front panet, Motherboard, power supply and
4MHz Z80A cpu board. The system is truly modular allowing the user to build up the
system he requires in his own time.

$100 boards from a number of manufacturers will plug into the DPS1 IEEE $100
bus.

Just add $100 Memory Boards ~ S100 disk controller boards — $100 I/O boards —
$100 video and/or graphics boards — $100 EPROM boards

All Ithaca Intersystems OEM products including K2 disk operating system and

PASCALJZ on 8" floppy drives will run in the DPS-1.

DPS-1 with ee 4MHZ ge ae
PASCAL MICRO
DEVELOPMENT SYSTEM

irnaca [hpoderssystennus HAVE JUST

ANNOUNCED AN IEEE S100 SYSTEM WITH A
TRUE PASCAL COMPILER

FOR RESEARCH and DEVELOPMENT
LABORATORIES and TEACHING APPLICATIONS

The PASCAL System

@ DPS1 Mainframe with
hardware front panel.
@ Z80A 4MHZ
Microprocessor.
\L @ 64K Static Dynamic RAM.
vay @ Twin 8” Shugart or DRI
O —® Floppy Disc Drive, Power
9 Supply and Controller.
@ K2 DOS or CP-M Operating
System.

@ Pascal Compiler and
Macro Assembler.

@ 1/0 Board with 2 RS232 ports
and 4 parallel ports

i, we ane delivoung/

All prices quoted are exclusive of VAT.

SIRTON PRODUCTS (Surrey) 01-660 5617

MICRONEX (Bristol) (027589) 3042
NORTEK SYSTEMS (Merseyside) (0704) 67375
ENERTECH (E. Sussex) (0323) 870814

Telex: 299568 - Ref: ITHACA
© Circle No. 174

PRACTICAL COMPUTING January 1980

In defence of Cobol

YOUR LEADER on the Language Dilemma
(Practical Computing, October) prompts me to
rise to the defence of a language largely ignored
by you — Cobol. In your enthusiasm for Basic,
you tend to overlook the point that computer
languages have been developed for specific
purposes. All languages trade off advantages
against deficiences, and so the best language
for one application will often be unsuitable for
another.

Basic was developed as an educational
language and as such is, as you pointed out in
your editorial, simple to learn and use. This, of
course is precisely what the hobbyist needs. But
not all users of microcomputers are hobbyists
(or educationists). Small businesses do use
microcomputers and a sizeable number of
computing professionals read Practical
Computing — rather more than readership
surveys indicate — a copy will often be passed
around a large office.

A business user’s requirements are different
to other people’s. A businessman is often not
interested in complex calculations but in
record-keeping. Record-keeping consists
mainly of three parts: inputting data in a way
that a complete idiot can manage, storing and
retrieving data as required, and producing
reports in formats that non-computer people
can understand.

The hobbyist’s main interest is in getting a
program to work. Once a program does work,
itis probably not used a great deal. By contrast
the business user Is only really concerned with
actually using the program — and this implies
the tedium of maintenance. Maintenance must
not be underplayed; it was discovered a few
years ago that maintenance of software often
costs most than its original production.

Worse, many business users who want to
modify computer systems find it easier to re-
write their programs than to try to under-
stand the existing coding. This is one reason for
the interest in techniques such as structured
programming.

For these business requirements, Cobol is
superb. Its data division allows input trans-
actions and report lines to be defined instantly.
It has excellent validation routines. Its long
mnemonics (up to 30 characters) and
structured approach make maintenance much
easier and therefore cheaper. When you can
write a command like:

IF STOCK-QTY NOT NUMERIC PERFORM REJECT-
TRANSACTION

there is little temptation to skimp on
validation. Consequently the sort of situation
you wrote about in your September leader,
where certain input patterns lock up the
program, can be avoided.

Even so, Basic is the best language for the
hobbyist. This does not mean, though, that
Basic is the only language that can be used. In
your last two issues you have, very rightly,
been highly critical of shoddy software. You
would do well to make a positive contribution
and promote professionalism and discourage
an amateur approach to commercial software.

Professionalism is not as much fun as
amateurism — but that’s life. It takes an effort
to learn Cobol. By the same token, to produce
good quality software requires hard work and
it’s not always fun. Anybody buying business
software should bear in mind that software
written in a language like Cobol is likely to give
less problems than software written in Basic. If
the vendor will not invest in a good compiler,
or has not bothered (or worse still, has not had
enough experience) to learn a powerful

PRACTICAL COMPUTING January 1980

language, he is unlikely to produce good
software.

By all means, Practical Computing, promote
Basic for what it is, but spare a thought for the
more serious users of small computers and
remember the professional tools now and
again.

John McMillan,
Calcot,
Reading, Berks.

Real cost of Z8000

THE EDITOR’s note (November Feedback)
suggests that the Z8000 is overrated. Although
its price is high, it is lower, in real terms, than
that of the new 8080, probably less than half.

It is a red herring to suggest that one needs 8
Mbyte to realise its potential.

Ignoring initial high prices, which will surely
drop, the Z8001 (rather than the Z8002) would
be my first choice, amongst present production
types, for an easy-to-operate small system.

I have already done some machine code
programming for the beast and it is a real
pleasure to use the large number of registers
and the simple systematic instruction set.

The power to address several memories, each
of 8 Mbytes, permits a simplified approach to
small memories with minimum risk of address
errors when programming. Code efficiency is
such that most programs are likely to use less
bytes than with current 8-bit processors and to
run much faster.

A final bonus is that the system can grow to
any size that the future dictates, without having
to be scrapped because of design limitations.

We are already promised that the MC68000
will be even better. Time will show. With either
choice, the small system is likely to emulate the
main frame in flexibility.

If one is using Basic the MPU hardly matters
but for simple machine code programming
with maximum efficiency, the more powerful
the instruction set the better. It can hardly be
too powerful.

R. G. Silson,
Tring, Herts.

QWERTY query

I WAS interested in the first illustration in
‘Possum on Pet’ (Practical Computing,
November), specifically the first sentence dis-
played, ‘‘The quick brown fox jumped over the
lazy dog.’’

I believe this is a misquote of a sentence well-
known to many thousands of typists, and
should read ‘‘The quick brown fox jumps over
the lazy dog’’. This latter sentence contains
every letter of the alphabet in a minimum
number of words, and is therefore very useful
in testing both typists and keyboards.

These are variations I have heard of —

@ The quick brown fox jumps over the lazy
dogs back.

@ The quick brown fox jumps lazily over the
gates.

I have been told by some that the originator
of this sentence was Sir Isaac Pitman, and by
others that it was Lewis Carroll, but although I
have searched numerous sources, I have failed
so far to find its origin. Perhaps some of your
readers could help me?

I would also like to know if there is any
generic name which describes such short

a NE 22702 yl

sentences or phrases containing all the letters of
the alphabet, and if there are any equivalent
ones in other European languages?

Reginald Mascall,

Berkeley Nuclear Labs,

Glos

TV applications

HAVING WORKED as an electronic engineer
in the television industry for the last 13 years, I
cannot allow your article (October 1979) on
David Graham’s work to go without comment.

A number of staggering generalisations have
been made which can only mislead. The
reference to portable TV and cameras and
recorders presumably refers to ENG EFP
equipment, which, while it certainly has a place
in journalism, can in no way replace existing
equipment without substantial lowering of
technical standards. Those of us who have seen
programmes originated in Italy, USA, etc using
these techniques would be horrified to see this
appear on UK TV screens.

I would be the first to agree that over-
manning does occur in the TV industry, but
this is a union rather than a technical problem.

Computers are making significant inroads
into TV studio technology, perhaps too slowly,
but computer-controlled lighting grids,
switching matrixes and vision mixers do exist,
and it is not the engineers that are ‘knocked
out’, as David Graham suggests, but the
production staff.

J. Hill,
Reading, Berks

Have a go!

I WAS looking through my son’s November
issue when I noticed the letter from Mr Short. I
wouldn’t like to think is comments might deter
some people from having a go!

My son, who is an apprentice, decided after
perusing magazines, to build a Triton L5.1. As
always seems to happen there were minor diffi-
culties, with the tape I/O in our particular case,
but letters to Transam were promptly answered
and a few friendly chats on the phone were
helpful too.

I feel the youthful enthusiasm at Transam
was the main reason for us now having a
working computer and my son has gained a
valuable insight into the technicalities. It is very
often an advantage to know how a tool is
made, as well as being able to use it.

Eve Ralphs,
Orpington, Kent

Reader interface

HAVING BOUGHT my first copy of Practical
Computing, I have one complaint: some of the
figures are impossible to read, eg, November
1979, page 87, figure 1 and 2.

The article on interfacing a PET to the real
world is a completely wasted effort as a result.
M. R. Halse,

Herne Bay, Kent

Our apologies: reproducing such technical
figures is a constant problem. Sometimes a
diagram that is readable in proof is illegible in
the magazine because of over- or under-inking.
We keep working at it! — Editor. hl

Prestel users
can cut bills
with Apple

KEEN COMPUTERS are to
offer their Apple users access
to the Prestel network without
buying a special Prestel TV set
and terminal.

Prestel is already available in
London and the Post Office
has promised to extend access
to Birmingham, Manchester,
Edinburgh and elsewhere as
soon as possible.

Prestel users pay for every
page of information each time
it is used; with a computer as a
terminal you would be able to
store the information on disk
and save on telephone charges,
especially if a page could be
useful for some time.

The Apple could be used to
call up pages automatically and
extract particular information
to be used as program input. It
is also hoped to use Prestel as a
means of selling software for
the Apple,

Quick chip

AMI MICROSYSTEMS have
announced a version of the
6800 microprocessor capable
of executing an instruction in
800ns, which it is claimed is
200ns faster than any other
6800 chip currently available.

Designated the S68HO0, the
AMI device utilizes a 2.5 MHz
clock and can execute one data
access instruction per two
clock cycles. In all functional
respects, the S68H00 is iden-
tical to other version of the
6800.

In common with earlier ver-
sion of the 6800, the S68H00
utilizes 8-bit parallel process-
ing, has a bidirectional 8-bit
data bus and a 16-bit address
bus. There are 72 instructions
in the set, with seven address-
ing modes.

AMI Microsystems are
based in Swindon on Swindon
(0793) 31345.

Bop till
you pop

THE FIRST computer music disco
was held in the bar of the Poly-
technic of North London on Sth
December. The event was organ-
ized by the North London Hobby
Computer Club as the climax to a
competition for the best disco
music produced from any common
personal computer.

Computer chief
hits out at cowboys

A COMPUTER EXECUTIVE has hit out at the growing
number of software consultants taking advantage of the
boom in sales of naked microcomputers.

Gerry Cook, marketing manager of Logabax Ltd, said
at the UK launch of the Logabax personal computer that
because all personal computers are sold by the manufact-
urers without applications software, users are looking to
software houses and specialist consultants for assistance
and, in some cases, are receiving sub-standard systems, or
packages which fail to perform.

“‘Most of the individual con-
sultants around are both com-
petent and scrupulous,’’ he
said. ‘‘But some are taking
advantage of the boom in de-
mand and supplying systems
which simply to not work. In
addition, most users are
unfamiliar with what they
should pay and what they
should expect from a consult-
ant, which makes them partic-
ularly vulnerable to the
unscrupulous.”’

Rigorous vetting

Mr Cook called for some
form of registration of indiv-
idual consultants in much the
same way that the Computer
Services Association (CSA)
registers the larger consultancy
companies and software pro-
ducers. Companies must have
been in business for two com-
plete years and must pass a
rigorous vetting procedure
before they can be accepted as

by Duncan Scot

members and are then subject
to its code of conduct.

These criteria do not apply
to one-man bands or to new
companies and, because micro-
technology is so new, it is
usually these people who
undertake programming of
personal computers.

“Because most micro-
computer projects are of
necessity small, they are not
cost-effective for the establish-
ed consultancy companies to
undertake and the user is at the
mercy of the small company or
individual,’’ he said.

“I should like to see a code
of conduct and a CSA-type
seal of approval awarded to in-
dividuals — both to help the
end-user and to differentiate
the cowboys from the genuine
specialists who are doing a
worthwhile job.’’

OU launches
Micro course

THE OPEN University has
launched a microprocessor
course for industry designed
for ‘‘managers and decision
makers.’’ Costing £120, the
course is a self-contained
package involving 80-100
hours of study. It does not
include courses on either tele-
vision or radio.

The course material consists
of an Intel 8049 microproces-
sor, for training, an instruction
manual and six booklets,
entitled: (1) Introduction; (2)
Choosing a Micro; (3)
Producing a Micro-based
product; (4) Technique for
developing a Micro-based
product; (4) Techniques for
Implications; (6) Personal
Implications.

The course has_ been
prepared by the Open Univer-
sity as part of the Department
of Industry’s Microprocessor
Application Project. It does
not form part of any of its
degree courses.

Since the first publicity
about the course, there have
been 2000 applications. The
course was expected to start at
the beginning of December
but it is not restricted to any
dates and can be begun at
any time. Contact: Open
University, PO Box 188,
Milton Keynes, MK3 6HW.

Plato's promise of perfection

A COMPUTER-based edu-
cation system, which includes a
comprehensive microprocessor
training course, has been
announced by Control Data
Ltd. The system, called Plato,
has taken over 15 years to
develop and over £5m is to be
invested in making the course
available through learning
centres in London, Manchester
and Birmingham by the middle
of 1980.

Training problems

The microprocessor course,
Working with Microprocessors,
was developed as the result of a
research project undertaken, by
Controi Data, at the request of the
Department of Industry. They
were asked to suggest ways to
alleviate the critical microproces-
sor training problems in the UK.

Control Data believe that up to
150,000 skilled engineers and
technicians are in urgent need of
retraining.

The course consists of a variety
of training modules, from a six-
hour introduction covering
computer fundamentals, the
fundamentals of microprocessors,
microprocessor programming and
interfacing, analogue and digital
conversion and the use of serial
and parallel devices, trouble
shooting and higher languages,
and specific applications.

The courses are entirely flexible.
Each student will have his own
interactive terminal, at the
Learning Centre, connected on-
line to a Control Data mainframe.
The student can move at his own
pace and is quizzed at every stage
to ensure that he has achieved the
required level of competence. The
aim is for everyone who takes the

course to leave at the same
standard.

Control Data claims that the
courses have been designed by
good teachers and designers, ie not
programmers, who understand
how to keep a pupil’s attention.
The courses can, apparently,
become addictive!

Get sponsored

By making the courses available
through the computer education
system, Control Data believes that
it is providing a means to solve the
national training problem. The 60-
80-hour course will cost around
£500, which is expensive, unless
you can be sponsored by your

company.
Further details are availble from
Neil Spoonley, Director of

Education Services, Control Data
Ltd, 179/199 Shaftesbury Avenue,
London WC2. Tel: 01-240 3400.

PRACTICAL COMPUTING January 1980

Scribble
nibble

QUEST AUTOMATION has in-
troduced an updated version of
its Datapad which allows hand-
written data to be entered directly
into any computer via a standard
Serial interface. The device,
Micropad, occupies no more
desk space than a telephone and
only costs £1725 compared with
£21,000 for Datapad.

Micropad does not need special
paper; the user can design his
own documents and data can be
entered with an ordinary ball-
point pen. The surface of the
pad is sensitive to pressure and
gives each contact point an XY
coordinate, tracking the pen as
it moves.

The microprocessor-based device
records how each letter is con-
structed and compares them with
a dictionary of different writing
styles. It can distinguish between
the number 8 and the letter B as
they are written in different
ways. As each letter is written,
a 40-character visual display lets
the operator confirm that the
correct letter has been recog-
nized.

Quest is financing its new Micro-
pad factory by floating 1.5m. of
their shares which are hoped to
raise over £1.2m. The factory is
at Wimborne, Dorset. Tel:
Ferndown (0202) 891518.

Microwriter
launched

Another device which could well
touch a similar market is the so-
called ‘pocket typewriter’.
Microwriter was originally dem-
onstrated in 1978 and launched
commercially at IBS last Octo-
ber. It is a portable battery-
Operated five-finger machine,
the size of an electronic calcul-
ator.

Words are keyed by the fingers of
one hand simulating the shape
of a character. The letter ‘I’, for
instance, is formed by pressing
the button under the thumb and
the index finger to resemble the
vertical stroke. About 1500
words can be stored in the de-
vice’s memory, edited and re-
formated.

The microwriter can be plugged
directly into a printer for a typed
copy, or a TV monitor and, for
additional storage, a micro-
cassette recorder.

About 90 Microwriters are already
in trial installations where speeds
of up to 80% of handwriting
have been reached and sus-
tained. Microwriter Ltd, which
is backed by Hambros Bank, is
based at 7 Old Park Lane, Lon-
don W1, 01-493 5633.

New Tandy for 1980

THE NEW TRS-80 Model II has been shown in the UK
and Tandy has announced that it will start taking orders
although the first shipments are not expected until April
1980.

Ted Russell, director of Tandy’s computer division,
claims that the Model II is comparable, in performance,
with the IBM 5110, the Hewlett Packard H9800, and the
Wang WCS1S. A basic configuration with 32K of RAM
and “%MB of additional storage capacity will sell for
around £2000. This can be expanded to 64KRAM with
2MB storage for around £4000.

Model II has been designed
as a business system starting at
the upper limit of the Model I,
the old TRS-80. The entire
computer and 80 character
monitor is housed in one box
which includes a ROM disk,
two serial and one parallel
ports. It is claimed that the

Model II will operate at 2% |

times faster than the Model I.
Tandy hopes that it will have
peripheral hardware and soft-
ware in this country by the first
delivery dates.

Although the Model II in-
corporates new features which
must have been included to

Little Genius
for micro

teach-in

FRUSTRATED USERS who
have struggled through barely
comprehensible manuals on
how to program their micro
might find Little Genius from
Applied Data Education
Services a life-saver. The Little
Genius diskettes are claimed to
replace text-books and
manuals with a series of easy-
to-follow screens and exercises.

The first two courses for
Apple II micros — Applesoft
BASIC and Using Your Apple
— are now available. Four
more courses for Pet and
Tandy micros will be issued
within the next few months —
Petsoft BASIC, Using your
PET, Tandy BASIC and Using
four TRS-80.

The courses are being
written by Baldchin Ltd in
association with ADes and wil
sell for £46 each. ADes is on
01-580 6361.

@ SEVEN NEW TANDY com-
puter stores will be opened by
the end of January from Birm-
ingham and Bristol to South-
ampton, each of which will
have a resident engineer.

PRACTICAL COMPUTING January 1980

some degree in response to
criticisms of the Model I, such
as a lower cse facility for word-
processing, the Model I will
continue to be sold. As if to
emphasise the point, the Model
I prices have been reduced by
about 10%. The TRS-80 4K
RAM Level I BASIC will now
sell at £385.

It will be interesting to see
how the Model I market will be
affected by the news from the
States that Tandy will be
selling a home computer, with-
out a monitor (to use with a TV
set) from the second half of
1980.

Micro event set

a |

Awards for
best-selling

computer ads

ENTRIES have been invited
for the Computer Ad-
vertisement of the Year
Award 1980. Over £7m is being
spent every year on computer
advertising so organizers
Crouchmead Ltd expects a
high response. Entry fees will
be donated to the BCS
Disabled Group.

Four categories of advertise-
ment will be considered —
computer hardware, computer
software, computer related
products/services and recruit-
ment. The panel of judges will
be asked to consider the
aesthetic as well as the inform-
ative merits of the entries.

The entries will be judged
and the winner announced on
Tuesday, 25th March 1980 at
the West Centre Hotel. Send
for entry forms from John
Godley, 42 Great Windmill
Street, London W1, on 01-437
4187.

for macro success

MICROSYSTEMS 80 looks set to break another micro
record. With more than 80 stands already sold for the
exhibition, at the Wembley Conference Centre from
January 30-February 1, 1980, it will be the largest

specialised micro event ever held in the UK.

The four-part program includes a Professional -Development
Course which aims to provide managers and engineers with an
introduction to micros and, for those with a specific interest in

software, to Pascal.

The Conference will provide
delegates with a state-of-the-art
review of developments in the
microprocessor field, with sessions
devoted to New Developments,
Systems design and specification,
Software for micros and Micros in
Control. The third day has been
designed to appeal to those
interested in personal computers
and their growing significance in
the business world.

There will also be a Buyer’s
Forum, held in parallel with the
Conference Sessions, which will
try and help prospective buyers
establish criteria for selecting
equipment.

There will be no charge for
admission to the Exhibition, which
is being co-sponsored by Practical
Computing. For further details
about the Conference, contact
Iliffe Promotions, Dorset House,
Stamford Street, London SE].
Tel: 01-261 8437/8.

Ignorance is
no excuse

PERSONAL COMPUTERS Ltd
have produced some laws of per-
sonal computing betraying
homely prejudices and, of
course, some traits from com-
puting’s more sinister followers.

It begins with such useful home
truths as ‘‘Personal computing
equals interactive computing’
and ‘‘Software is hard: hardware
is soft,’? and continues with
‘‘BASIC is to personal comput-
ing as sign language is to Eng-
lish’? and ‘‘The goal of personal
computing is to reduce the
differences between humans and
computers.”

Personal Computers also tell us
that they are going to reduce their
dependence on the Apple and
start distributing the TI-99/4
within the next few months. [J]

Vincent Tseng peeks at Hewlett Packard's HP 41C. Could this
be the forerunner of a portable micro, nestling in the pocket

of the future?

Has the pocket
computer arrived?

THE POCKET has a great deal of
significance in landmarking history. For
example: the introduction of the pocket
radio back in the early 1960s, the pocket
calculator in the 70s and more recently the
pocket TV. Now there is speculation on
the pocket computer. Hewlett-Packard’s
HP 41C programmable calculator has
been heralded as the first pocket
computer. Is this title justified? Is it an
indication of things to come?

Everyone’s definition of ‘‘computer’’
will be slightly different. Remember when
the early pocket electronic calculators
were first on the market? They were
called, and even advertised, by many as
computers. Of course most people will
now laugh at those claims. To be pedantic
about it, the electronic calculator is based
on microprocessor technology: if the
internal architecture is examined, it is
easily recognised as that of a computer.

Without rhetorical discussions on what
is or isn’t a computer, the most sensible
approach is to compare it with equipment
which has already been classified. I have
chosen equipment with which I am
familiar, and which is in a similar price
bracket.

These are the Rockwell AIM-65
(reviewed in PC, July 1979) which I
assume most people would classify as a
computer, and the Texas Instruments
TI-59 programmable calculator, which
has been around for about 2-3 years and
has always been called a calculator. These
comparisons do- not bear on value for
money or relative performance.

The choices for comparison are quite
appropriate. The TI-59 is fairly obvious,
being a calculator of similar class and
price but from a different manufacturer.
The AIM-65 was chosen because it
offered similar facilities in terms of

Hewlett Packard’s HP 41C calculator with printer, alpha-numeric display, magnetic and
ROM memory modules, light-pen and programs in bar chart form.

display and output.

In appearance, the two calculators both

look like calculators of three to four years
ago, ie, fairly bulky, more coat than
waistcoat pocket-sized. The AIM-65 is a
typical single board computer.
@Keyboards: the HP-41C and the TI-59
both have typical calculator key layout,
while the AIM has a full alphanumeric
keyboard in the conventional typewriter
layout. All three have printer output
capability on 2in wide roll paper using
thermal printing. The AIM had the
printer built-in but with the calculators
this is an optional extra.
@Displays: the AIM and the TI-59 both
use LEDs, 20 characters of upper case
alphanumerics for the AIM, whereas the
TI-59 has 10 numeric digits only. The HP-
41C used LCD capable of displaying 12
characters of upper-case alphanumerics
with indicators of the chosen mode.

PRACTICAL COMPUTING January 1980

@Power supplies: the HP-41C used
disposable batteries (the new half penlight
size) which Hewlett-Packard claims will
last about one year. The AIM needs a
stabilised +5V at 2A and +24V at 0.25A
and is therefore usually powered from the
mains. The TI-59 is rechargeable, so can
work off the Ni-Cad pack or from the
charger/mains adaptor.

The HP-41C was fairly easy to use as a
normal calculator, although it uses the
Reverse Polish Notation (RPN). This
method was not difficult to understand,
but a little awkward, in my opinion. The
best way to remember the principle of this
method is that the order of operations is
the order in which one calculates an
equation. Although this sounds logical,.
my preference is for the algebraic notation
with hierachy as in the TI-59.

The difference is that in the TI-59
method one enters the equation as written
and the calculator takes account of the
operational hierachy order, so on pressing
the ‘‘=’’ key the correct answer appears;
with RPN one has to first analyse the
equation and decide which operation
should be calculated first and the order of
the rest of the operations. However, RPN
does dispense with the necessity for
brackets. The difference is a bit like that
between a high-level language and that of
an assembly code but not quite as marked.

A feature of the HP-41C which the
other machines lack is that it retains the
contents of memory when the calculator
has been turned off. Memory is held in
low-powered standby mode. This means
that the batteries cannot be removed for
more than a few seconds without corrupt-
ing or losing the contents. This ability to
retain the memory is a very convenient
feature.

I found that it was all too easy to clear
the program memory, especially when
attempting to append operations on the
end of a program, or when trying to write
a program into the remaining free area.
This is a shortcoming which needs serious
consideration. I feel that programs should
be capable of being protected in memory,
or even automatically protected, with an
operation which needs to be made
obviously deliberate for clearing the
memory.

The programming operations, editing
functions and instruction/function set are
similar for the two caiculators. Both have
numerous built-in extra functions, but the
manipulative and testing functions are
primitive. The AIM-65 does not have the
powerful calculator functions, but the
instruction set is much more suitable for
testing, manipulation and the moving of
data.

Therefore the programmability of the
HP-41C (and the TI-59) is much more the
capability of stringing together calculator
functions, with some basic test
conditions, to make the calculation of
long equations and expressions less
tedious and more automatic.

PRACTICAL COMPUTING January 1980

Although it can be argued that many
computers are used for calculations,
computers do have the ability to manip-
ulate data in a far more sophisticated way
than either of these machines. But, no
doubt, both manufacturers would be the
first to admit that the calculators were
designed primarily for calculations.

Taking the above discussions into
account, the ability of the HP-41C ‘to
display alphabetics can be viewed in
context, as that of making the calculator
more convenient, and more meaningful
for messages and prompting. But I found
the keyboard awkward to use for alpha-
betics. The letters are placed in alpha-
betical order, starting from the top left-
hand key, and perhaps because of this,
letters were surprisingly difficult to find
quickly. It did not help that letters were
marked on the sloping vertical face of the
keys, which meant that the markings were
not very prominent and that the calculator
needed to be tilted away from the user to
be viewed clearly. This feature, although
not very convenient in its execution, does
take the HP-41C a step closer to what is
generally accepted as a computer. This
certainly was one of the attractive features
of the AIM-65 as well: the ability to
display meaningful messages.

More permanent storage, or mass
storage, is achieved by the use of magnetic
strip cards for both calculators. The
TI-59’s is built-in, the HP-41C’s is an
optional extra. Each card can store
approximately 200 steps in both systems.
The AIM uses domestic audio cassettes,
and can store about 100Kbytes on a C-60
per side, that is about 50,000 instructions.
All three systems are tolerable in terms of
speed and convenience.

Strangely enough, all three really come
into their own when the printers are used.
All three can trace their respective
programs by means of automatic single
stepping, all three ‘‘disassemble’’ the
program steps into either the calculator
operations, or into their mnemonics. The
TI-59 and the AIM print the machine code
stored in memory, but the HP-41C does
not. All three printers can print full
alphanumerics upper case only. Plotting
simplified graphs is reasonably conven-
ient with both the HP-41C and the TI-59,
but with the AIM the user would have to
write his own general routine.

A few niggly points about the HP-41C.
It does have quite a number of built-in
extra functions which are not marked on
the keyboard. However, it is really fiddly
to access them. The sequence is to press
the ‘*XEQ”’ key, set the calculator into
alpha mode, key in the mnemonics for the
instruction, re-press the alpha mode
switch (to take it out of the alpha mode)
then the digits for the operand. So an
instruction of four characters takes seven
key-strokes to enter! This is stretching the
use of alpha capability for the sake of the
facility.

_ es

The other point is the speed of the
printer. It is slow, and for one based on
the latest technology, surprisingly dumb
when it comes to straightfoward printing.
It does not have bi-directional printing,
and worse: it has to print a full line of 24
characters, filling in with 23 spaces, even
when only one character needs printing.
This is really a silly oversight.

The HP-4I1C claims to be a ‘“‘system’’,
with various expansion options. Printer
and mag card reader as mentioned, and
with extra memory plug-in modules —
either ROM or RAM — each can add
about 640 steps or 380 alphanumeric
characters (note a number entered as an
alphanumeric is not interchangeable with
a digit entered for calculation). Up to four
modules can be added, taking the total
memory area to about 3.2K steps. In
comparison the TI-59 has a total built-in
memory of 960 steps. The AIM has
1Kbytes, expandable to 4K on board. The
TI-59 in addition takes a plug-in ROM
module containing about 5,000 steps and
the AIM can have 20K bytes of ROM on
board.

{ found the HP-41C’s documentation
infuriating. Hewlett-Packard claims it was
written by prize-winning teams for
manual writing, but I found it next to
impossible for quick and concise refer-
ence. For example an easy-to-find (if it
does exist, I did not find it) reference of a
list of the functions not marked on the
keyboard and how to enter them, would
have been useful and much appreciated!

Although I can see that the manual
might be good for a first-time user, I did
not find it particularly easy to learn
quickly from it, and also I found it a little
patronising. In contrast, the manual of
the TI-59 was, in my opinion, excellent,
both for a beginner as well as for a
reference manual.

Conclusions

@As a calculator, the HP-41C is certainly
one of the most sophisticated I have come
across, although the TI-59 rivals it quite
closely.

@As a computer, I feel it still has some
way to go (unless of course one regards it
as a dedicated calculating computer).
@The main limitation that I foresee for
the advent of the true pocket computer, is
the restriction of the size itself — limiting
the computer by its keyboard and display,
so it will always be relatively inconvenient,
unless some dramatic advance can be
made in ergonomic design.

@Any claims to being a computer cannot
be justified, since the TI-59 matches
almost point-for-point the capabilities of
the HP-41C, and the TI-59 has always
been regarded as a calculator.

@The HP-41C is nevertheless a significant
step forward toward the pocket computer,
and I do not intend to argue too
vigorously with those who might claim
that it has arrived!

At home on the range

Practical Computing examines a rugged business system
built for the Texas oilfields.

by Martin Collins

THE TEI RANGE of computer systems is
imported and sold in the UK by Abacus
Computers Ltd. Abacus was set up about
a year ago and also supplies the Compu-
color II and a range of cut-price periph-
erals, including the Texas 810 printer.

TEI systems are based on the S100 bus
with 8080 or Z80 processors. There are
three basic models which may be con-
figured with mini or standard disc drives:
@ PT 112,212,312, and 412 which have a
12-slot $100-bus, integral keyboard and
15 inch CRT. The disc configurations are:
PT112: Single mini drive; PT212: twin
standard drives; PT312: twin standard
and single mini drive; PT412: two twin
standard drives.

@ PT208 and 408, which have an eight-
slot $100 bus, integral keyboard and 15in
CRT. The disc configurations are: PT208:
twin mini drives; PT408: twin mini and
twin standard drives.

@ MTS 22, a 22-slot S100 ‘mainframe’
but without the integral CRT/keyboard,
and with two standard drives.

All the systems are supplied in heavy-
duty aluminium cabinets with an 8-, 12-,
or 22-slot motherboard, a 17 amp
constant-voltage transformer power
supply and a fan. The standard systems
include a 2Mhz 8080 CPU card, two 32K
of memory, and an interface card giving
three paralleled and three serial ports.

The memory consists of 16K _ static
RAM cards which allow any 4K block to
be addressed to any 4K boundary in the
system. The memory can be increased to

The top row of the keyboard has eight user-definable keys, useful for process control,
and eight lights connected in parallel with the disc access port. These lights can be user
defined, with labels put next to them to signal specific conditions to an operator.

48K or 60K. The top 4K is reserved for
system I/O and the video controller screen
memory. A 4Mhz Z80-based processor
card is available as an option and a SMhz
8085 card will be available soon. The
processor cards contain two 1K PROMS
which handle all system I/O.

The 9in and 12in CRT displays are
driven by the same CRT card which gives
24 lines of 80 characters. Upper and lower
case characters are displayed using a5 x7
dot matrix. There are 2K bytes of memory
allocated for the CRT screen, addressed
from F800 to FFFF and this may be
accessed by the CPU and the CRT card.

A TE! with twin mini drives in its natural habitat. Note the solid construction and
numerical keypad.

The cursor may be block or underline,
blinking or not blinking. As the CRT is
memory-mapped, it is fast and the user
has direct control over the display.

The floppy disk controller board will
handle up to eight drives which may be
any combination of 8-in and 5-in devices.
The drives currently available are the
Shugart SA400, with a capacity of
80Kbytes, and the Shugart SA800, with a
capacity of 250K. Double-density disks
will be available soon.

The disk controller uses the Western
Digital FD1771 LSI chip and can handle
double density drives when they become
available. The 8-in disks are soft-sectored
with 128-byte sectors in IBM format.

The input/output board has three
parallel and three serial ports with select-
able band rates from 75 to 19,200 and
RS232 and TTL signal levels. The serial
port may be configured for different
numbers of character bits, stop bits and
odd or even parity. One of the three serial
ports is software-programmable and the
other two are jumper-selectable.

The systems have the CP/M operating
system and a choice of languages,
including, TEI Extended Basic, C BASIC,
FORTRAN (Microsoft), CIS COBOL
and Pascal.

CP/M is already accepted widely as the
‘standard’ operating system for S100
8080-based systems.

The TEI Basic is available in 4K, 8K,
extended and disc-extended versions, the
last of which is sold and supported by
Abacus.

Features of the Extended Basic include

PRACTICAL COMPUTING January 1980

a a a oy a er 0)

Practical Computing evaluation

Yes/No
NA

Ease of construction (where

applicable) NA

[ Assembly language

Basic language *

Quality of documentation

Dealer support/maintenance

Can handle 32K of memory

Quality of video monitor
(consider resolution and
screen size)

S$S-50 Bus
S-100 Bus
Sockets for chips

Numeric, calculator-type
pad on keyboard

Large amount of removable
memory, randomly accessible

Cassette tape recorder
capability: Own

Built-in recorder

Communications capability
(can talk to other computers)

Speed of Instruction cycle
Ease of expansion

Low power consumption

single (seven-digit) and double (16-digit)
precision floating point arithmetic; integer
variables. String variables and array-
strings may have up to 255 characters;
variable names may be of any length but
only the first two characters and the type
symbol, which must be the last character,
are significant. The type characters are:

= string; % = integer; ! = single pre-
cision; = double precision.

Errors can be trapped and handled by a
standard subroutine using an ON ERROR
GO TO statement. There are sequential
and random files, and an EDIT command
for amending source statements.

Overall, it is a very comprehensive Basic,
but it uses the same technique for
handling random files as that developed
by Digital Equipment for Basic Plus
under RSTS/E. It uses a FIELD state-
ment to define variables within a disc
buffer and LSET, RSET and conversion
statements — CVI, MKIS — to convert
numeric variables to or from the disc
format. If that sounds complicated, it is!

It certainly is not the best way of hand-
ling random files in Basic. Abacus says
that TEI Basic is used by its scientific and
technical customers, while commercial
users opt for CIS COBOL or C BASIC.

Abacus is developing a set of commer-
cial packages, sales, purchase and
nominal ledgers, stock recording, and in-
voicing. The sales ledger has been installed
for one customer and the purchase and
nominal ledger packages are virtually

PRACTICAL COMPUTING January 1980

pal
nn

| NO |

Floppy disc capability
VES

| 24 Mee |

See Ce

Other languages

Compatibility with other
systems

Appearance
Portability

packages available
Hobby use
Business use

Education use

Suitability for:
Commercial applications

Home applications

Bane Educational applications
ae |) Ability to add printer(s)

VERa Ability to add discs
ane

im) Ability to add other

| | | |@] | Ratings

N/A = not applicable.

complete. They are being written in CIS
COBOL.

Abacus was unable to let us have a
system on loan, so we had a demonstra-
tion at its premises. The machines are not
the most beautiful we have seen, but they
have steel cases and appear to be very
well-built. The legend is that the TEI was
built to survive in Texan oilfields.

Reputation for
reliability

Abacus has now installed 50-60 and
claims that they are very reliable. It is
interesting that a number of other manu-
facturers, notably Alpha Micro, which
has developed a 16-bit S-100 system, uses
the TEI card cage, S-100 bus, and power
supply as the basis of its system.

Its reputation for reliability is one of its
strongest selling points. Our experience
with a wide range of micro-computers has
shown that some are so unreliable that
they cannot be used for commercial
applications.

Abacus was reviewing its prices at press-
time and was expecting to reduce them
considerably. Prices we were quoted
ranged from £3880 for a PT112, 15-in
CRT and the mini-floppy, to £6248 for a
PT412, 15-in CRT and two twin standard
drives. These prices make the TEI system
one of the most expensive on the market.
But if you are thinking of buying a system
for regular commercial work, it might be

Reputation of manufacturer

No. of software applications

manufacturers’ plug-in memory

1 = poor; 2 = fair; 3 = average; 4 = good; § = excellent.

Yes/No
N/A

YES

SOON

*C. Basic ... 4
Disc Basic ... 2

worthwhile paying the extra for reliability.

Abacus has appointed three distributors
for the TEI system: Micro Shade of
Calne, Wiltshire; Stewkley Computer Ser-
vices, Lincolnshire; and Strattenden Ltd,
Isle of Man, and is quoting three weeks
for delivery.

As for support, hardware maintenance
is available by Computer Field Mainten-
ance. The charge is 11 per cent of the
hardware value per annum, and the
response time for a fault call is quoted as
one working day.

As the system uses standard CP/M
software, a user should have no problems
in obtaining support from a variety of
sources. Abacus says it has used a variety
of ‘standard’ S100 hardware and CP/M
software products with the system and has
no problems in interfacing.

Conclusions

¢ The strongest point of the TEI system is
its robust construction and reputation for
reliability.

© The disc capacity is somewhat limited at
250K bytes per drive for a standard disc
and 71K bytes for a mini. Double density
will be available shortly.

e The systems are expensive but are worth
considering because they are very well
made.

The Abacus commercial packages will
not be the cheapest on the market — the
expected price is £2,000 to £3,000 — but
good software is not cheap. Q

E38)

As cash shortages squeeze hospital budgets even tighter,
one department has come up with a novel micro application
to take some of the burden from nursing staff.

Whose hand rocks the cradle?

PREMATURE BABIES might be saved by microprocessors, if research at
the Royal Postgraduate Medical School bears fruit. A microprocessor
based device. which controls the level of oxygen a baby receives, has
been developed and is now being tested and refined.

It could well be the first time that a microprocessor has been used to regulate and
monitor clinical conditions. The experiment is part of a series of microprocessor-based
research projects at the School, based in Hammersmith Hospital.

Babies are sometimes born as early as 25 |
weeks gestation, weighing as little as 1.5 Ibs.
These babies have to be incubated if they
are to have a chance to survive. During this
period, the level of oxygen they breathe is very
important as the partial pressure of oxygen, in
the blood, has to be maintained at a critical
level. If the blood oxygen rises too high, there
is a possibility that the baby could go blind,
too low and it could suffer brain damage.
Oxygen is supplied to the baby either through
a face-mask ventilator or a head-box, depend-
ing on its condition.

Four years ago Paul Collins, an engineer in
the Child Health Department, started to design
an automatic oxygen level control and
monitor. The work was supported by a Well-
come Foundation grant to the Child Health
and Medical Physics Departments. This was a

solid-state device which would monitor and =

regulate the level of oxygen in a baby’s blood | Above: Paul Collins.

that concerned with the safety checks in the
control. It is vital that a nurse is immediately
warned if anything goes wrong with the
equipment or the baby. The control has a
number of self-checking devices — for example
the inspired oxygen level is continually checked
against the position of the valve. If the two
readings do not agree, an alarm is sounded.

There are many occasions when a nurse may
have to be called. Sometimes a baby’s
condition can deteriorate very quickly. One
fairly common difficulty with premature babies
is that their lungs can become blocked with
fluid. This can clear in a matter of minutes and
the amount of oxygen absorbed through the
lungs can increase dramatically. Although the
mixer valve should be able to deal with most
adjustments, a nurse will always be called
whenever there is a dramatic change of
condition.

It is difficult to predict whether this added
supervision of a baby’s condition, if it is ever
fully developed and applied, will have a sig-
nificant effect in saving the lives of premature
babies. It could be that the first noticeable
factor will be an increase in the number of
premature babies which survive without any ill-

by changing the level of oxygen being supplied | Below: An MSI 6800 is used to analyse the information from this

to the baby with a valve which controls the ultra-sound scanner (see next page).
mixture of oxygen and air.

by Duncan Scot

The level of blood oxygen is measured by an
electrode strapped to the baby’s skin. It heats
the skin to around 40°C, dilating the pores on
the skin surface and allowing oxygen to be
transferred to the electrode. The output from
the electrode is dependent on the blood oxygen
level.

If the level of blood oxygen is too high, the
setting of the mixer valve has to be adjusted.
The difficulty lies in designing a system which
has a flexible response and can return the blood
oxygen level to normal in the quickest possible
time. The solid state design required a lot
of complicated electronic circuitry but made
it hard to incorporate further design ideas as
the project evolved.

A microprocessor offered more flexibility. It
was a relatively simple matter to base each of
the response levels in software. Mr Collins’s
system now consists of a Motorola 6800 micro-
processor, a 6810 RAM, 1K of EPROM and 3
PIA 6820s.

The Wellcome Foundation grant expired at
the end of March 1979 and Paul has now
moved on to other work. But two American
companies have since expressed commercial
interest in the project. In the meantime, a
doctor at the Medical School is conducting
clinical trials with the system and, with Paul,
is looking at areas in which the software could
be refined.

The most difficult area of the software is

PRACTICAL COMPUTING January 1980

Paul Collins modifies his control unit.

effects, although such statistics will take years
to isolate.

There seems little doubt that the idea will be
developed commercially. The Ingtitute of Child
Health has already filed a patent on the system.
Paul Collins regards this as only the start of a
whole new range of increasingly sophisticated
microprocessor-based equipment which will be
able to control every detail of a baby’s
environment. None of this would have been
possible even a few years ago.

It is no coincidence that Paul based his work
on the Motorola 6800. The hospital has been
experimenting with the chip for several years,
has created its own expertise and promoted the
use of microprocessors and microcomputers
throughout the hospital. Much of this work has
been led by Professor Wootton, Head of the
Department of Chemical Pathology.

He came across the 6800 chip when he
studied an experiment at the National Institute
for Medical Research. His latest plans include
the installation of up to 20 microcomputers
within the next couple of years. Many of these
will be connected to the dumb terminals of the
hospital’s file-handling CTL 8050 mini.

Ultra-sound scanner link

One project, funded by a Department of
Health and Social Security grant, uses an MSI
6800 microcomputer with an ultra-sound
scanner. These are sometimes used to study the
position and movement of a foetus, or to pick-
up a change in the blood flow to an organ or
area of the body. In this case the scanner
examines tissue characteristics; the micro-
computer analyses the information (echoes)
which are not visible in the images. The
information from the scanner includes fre-
quencies up to 10MHz and is sampled at 20
MHz. This is digitized, unloaded into the MSI,
processed and analysed.

Typical applications include studying the
response of tumours to radio- and chemo-
therapy, the contractability of heart and other
muscles and the loss of efficiency in ageing
placentas. These are all long-term investi-
gations. The brief from the DHSS was to
develop a system which could be used with any
scanner in the country and which is not pro-

PRACTICAL COMPUTING January 1980

hibitively expensive. The development team
has been encouraged by its progress.

Another project highlights the practical
benefits of microcomputers in the laboratories
by relieving the pressure of the day-to-day
work of the hospital. In the Blood Count
Laboratory a complex machine, a Coulter
Counter, is used to analyse over 500 blood
samples every day. The counter prints, auto-
matically, the number of red and white blood
cells and the level of haemoglobin in each
sample.

The data used to be collected by an old and
unreliable paper tape punch, linked to the
counter by a specially-built interface. This has
now been replaced by an MSI 6800, costing less
than a new interface and tape punch,
connected to the Coulter Counter at logic level
and to one of the dumb terminals of the
hospital’s CTL minis. The data from the
counter can be stored and edited locally before
being transferred to the CTL’s files. The
terminal can be used as a stand-alone micro-
computer or as an intelligent terminal for the

CTL. Professor Wootton expects that many of | they can keep up their lead.

Applications aaa

the micros used in the hospital will eventually
be linked to the central mini.

Microcomputers and processors, inexpensive
by the standards of hospital equipment, have
great advantages. They are reliable and can
eliminate much of the repetitive drudgery
involved with medical research and treatment.
They will also allow new safety and super-
visory equipment to be developed which will
actualy save lives.

It is no secret at the hospital that everyone is

. Surprised by the speed with with micro-

processors have become involved in so much of
their work. The staff have been impressed with
the practical advantages and implications of
computers.

The Instrumentation Department of the
Medical School has concentrated all its micro-
processor efforts on the 6800 series of chips
and thereby established a standard of work
which seems to have ensured the economic
success of their projects. At a time when grants
and budget are restricted, projects must have
uses in other hospitals or departments.

Pressure from the field

The importance of the hospital’s work with
the MSI 6800 has not been lost on CTL. It has
recognised the advantages of attaching micro-
computers to its dumb terminals and has
included the MSI 6800s as an optional addition
to a medical package called Phoenix. This
system has already been installed in some UK
hospitals.

The Medical School seems to have developed
applications for micro-computers and
processors in a way which highlights some of
the problems in the micro industry. The best
ideas are not coming from the trade, which has
yet to demonstrate an ability or will to develop
its own application expertise. It is only fair to
add that the hospital has found its suppliers,
SEED, extremely helpful and have no
criticisms to make. All the same, it seems that
the pressure for development and better
software is coming from the field.

The widespread use of microcomputers at
Hammersmith has managed to break many of
the myths surrounding large centralised
computer systems. It would seem likely that
within the next few years micros will penetrate
into every area of the hospital. We hope that

Blood samples are analysed in the Coulter Counter. An MSI 680 is used to transfer the
data toa CTL 8050 mini.

Single-cell movements

tracked by computer

In the previous article, the concept of a parallel-processing computer was introduced.
The architecture of the CLIP (Cellular Logic Image Processor) machines built by the
Image Processing Group of University College, London was dealt with and some
image-processing applications were mentioned. This article introduces the reader to
the software of the CLIP computer and considers in detail some image-processing
techniques and their application to real problems.

AT A RECENT CONFERENCE held in
Windsor, leading members of the image-
processing fraternity discussed the
development of high-level computer lang-
uages for image processing applications.
The delegates split roughly into three fac-
tions: those who considered a library of
FORTRAN subroutines ideal; those who
wanted image processing-related instruc-
tions embedded in a PASCAL-type
language; and those who advocated a
completely new language. Until a high-
level language is widely accepted, image-
processing machines like CLIP will be
programmed in their inherent machine
languages.

The assembly language of CLIP4 (the
latest machine which should be working
by early 1980) is called CAP4 (CLIP4
Assembly Program). A CAP4 statement
typically consists of a combination of four
possible fields:

LABEL: OPERATOR OPERAND;

COMMENT

All statements do not require a LABEL
and the COMMENT is optional. The
LABEL consists of up to six alpha-
numeric characters from a limited set of
the ASCII characters, and fulfils the
usual role of a statement label in any
assembly language.

Instruction mnemonics

The OPERATOR can take the form of
instruction mnemonic or an assembler
directive. An instruction mnemonic
corresponds to executable machine code,
while a directive tells the assembler how to
deal with a program section or with a set
of characters. The nature of the
OPERAND is dependent on the OPER-
ATOR, while the COMMENT is self-
explanatory.

Instruction mnemonics fall into five
categories: array, register, branches, input/
Output; and miscellaneous: The

register, branches and miscellaneous
categories: array, register, branches, in-
put/output, and miscellaneous. The
register, branches and miscellaneous
two remaining categories only the array
instructions will be considered since these
reflect the CLIP4 architecture and show
how CLIP can be used for image process-

ing.

The CLIP4 machine consists of a 96 x
96 array of interconnected processing ele-
ments (PE’s), one of which is shown
schematically in figure 1. The array
instructions are of four types: LDA,
LDG, SET, and PST.

LDA simply loads the A register of a
PE with a single bit of data from a loca-
tion in the D-memory specified in the
operand field, eg LDA 10 copies the con-
tents of memory location 10 into the A
register.

Every PE performs this instruction at
the same time. Similarly, LDG loads the B
register from a specified memory location.

Figure |: CLIP4 cell.

INTERCONNECTION
INPUTS

(CARRY)

DATAINPUT

DATA OUTPUT

ENABLE B

2O——

BOOLEAN
PROCESSOR

INTERCONNECTION
O OUTPUT N
b44¢
|< | =

D LOAD CLOCK

PRACTICAL COMPUTING January 1980

ess, ci clic =

5 4

Figure 2: Square and hexagonal
surround directions for each CLIP cell.

The SET instruction is the basis of
array processing on CLIP4, since it spec-
ifies the manner in which the array will
operate during a processing cycle. It con-
sists of three subfields, which are: output
definition, propagation definition, and

Figure 3: Thresholding images.
(a) Biological ceil.

= ‘ity

(b) Grey-level histogram of (a). The darker shaded
values become Os and the ligher shaded ones
become Is at thresholding.

Numbers.
of pirels

PRACTICAL COMPUTING January 1980

default options.

The output definition consists of a
boolean function of the A (local image
value) and P (propagation from adjacent
cells) inputs, which are combined to pro-
duce a D output. The propagation defin-
ition specifies in a direction field, from
which adjacent cells an input will be re-
ceived, and also defines a boolean
function of the A and P inputs which are
combined to form the N_ output.

The default options allow the array to
be used with hexagonal instead of square
tesselation, the propagation signals from
the outer edge of the array to be set to
logical 1 instead of 0, and the R and C
control lines to be set to use each PE asa
full adder. A typical instruction would be:

direction

field specifying
accepted directions

A+ _p'glapE
a =

default option

D output N output

definition definition
Where + = OR
. =AND
— = NOT
@= EXOR

The numbered directions surrounding a
given PE are shown in figure 2, and the E

(d) Chromosomes.

default option sets the edge of the array to
logical 1.

The PST instruction is a mnemomic for
Process.and STore. When this is executed
the array goes through a processing cycle.
The data loaded in the A and B registers is
processed according to the functions de-
fined in the previous SET instruction and
the result is stored in the memory location
specified in the operand field of the PST,
eg PST 5 would process and store the
result (D output) in memory location 5.

A typical sequence of CAP4 statements
would be:

LDA 2

SET P,(8)A

PST 2

Local image value

The result would be a shift to the right
by one pixel of a binary image stored in
location 2. Consider the image to consist
of a white object (1s) on a black back-
ground (0s). The propagation definition
specifies that the value passed to adjacent
PEs is the local image value. However,
since only direction 8 is enabled, then a PE
only receives a propagation signal from
the PE to its left. The output definition is
PE and so takes on the value of the prop-
agation input. Thus, each PE passes its
own value to the right and takes on a new

(e) Grey-level histogram of (d). The meaning
of the light and dark shading is as for (b).

Number
of prrels

1006

(f) Thresholded version of (d).

value from the left and overall, a right-
shift of the image is achieved.

The removal of a single-point white
noise from an image is achieved using

SET A.P,(1-8)A

Each PE passes its local image value to
all of its neighbours (directions 1 to 8 are
enabled) since the propagation definition
is A. However, the output definition
means that only those PEs which contains
ls and receive a 1 propagation signal pro-
duce a 1 output. Thus, isolated Is (white
points) do not receive a propagation | and
become Os while clusters of any size
remain unaffected.

As a final example of the power of a
single CLIP instructions, the expand
operation will be explained. Expanding an
object involves adding layer of pixels all
around its edges. It is achieved using

SET A + P,(1-8)A

Spatial filters

Each PE communicates its local image
value to all of its neighbours. Those PEs
which already contain a | or receive a
propagation | (ie are next to a PE contain-
ing a 1) produce a | output. Thus, the 0
pixels (black) lying next to the object
edges become | pixels and the object in-
creases in size by one layer.

Even though the above examples are all
low-level assembly language statements,
they achieve results which would require
whole subroutines written in a high-level
language when running on a normal serial
computer. The limited arithmetic
capability of, and relatively coarse digit-
isation of, a picture into 96 x 96 pixels by
CLIP4 means that the machine is not
oriented towards enhancement and restor-
ation of photographs. Such tasks require
a much finer digitisation grid (maybe 512
x 512 pixels) and considerable arithmetic
power to implement numerical filters in-
volving, say, the Fourier spectrum. CLIP4
is better able to deal with what can be
loosely termed pattern recognition oper-
ations and some of these will now be
described.

Binary images

One of the simplest and most useful
methods of extracting an object from a
picture is by thresholding. Here, all pixels
with value greater than a specified thresh-
old are assigned local 1, while those with
value less than the threshold take on
logical 0. The result is hopefully, a binary
image that best represents the desired
object in the picture. Further operations
can then be applied to the binary image
without the complication of dealing with
grey-level values.

The problem is to select reliably a suit-
able threshold. A useful pointer comes
from the grey-level histogram of the
picture which shows how many pixels
there are for each value of grey-level.

Such histograms exhibit a ‘‘bimodal’’

structure. There is a valley between the
small peak of the predominant object
grey-level and the large peak of the pre-
dominant background grey-level, and it is
sensible to choose a threshold value that
lies somewhere in the valley for best separ-
ation of object and background. The
results of a program which automatically
selects the threshold value are shown in
figures 3(c) and 3(f). Obviously, if the
characteristics of the pictures are known
and are constant, then a single threshold
value can be determined beforehand and
used for all such pictures.

Two very important operators in image

Figure 4: Applications of the grey-level
shrink and expand operators

(a) Biological ceil

(b) Spatially filtered version of (a) to pick-out
the ‘‘limbs”’

processing are the SHRINK and the
EXPAND. For binary images, shrinking
is the process of ‘‘peeling’’ away the outer
layer of pixels from an object, while con-
versely, expanding adds a layer to the
object. The edge of a binary object can be
found by simply shrinking once and
exoring the shrunk version with the
original, leaving only the perimeter.
Combinations of shrinks and expands

can be used as spatial filters to remove
structures of certain sizes while leaving

others essentially unchanged. If a number
of shrinks is followed by the same number
of expands, then small structures dis-
appear during shrinking and do not return
when expanding. However, larger struc-
tures only reduce in size during the shrink-
ing phase and are essentially restored to
their original form on expansion.

Thus, shrinking followed by expanding
acts as a low-pass spatial filter. A lowering
of the pass frequency is achieved by
increasing the number of shrinks and
corresponding expands. A high-pass filter
is obtained by exoring the low-pass filtered
image with the original. Only the portions
of the picture which have changed then

‘Skeletonising’ objects

A special form of the shrink operation
can be used to determine the ‘‘skeleton’’
of an object. Skeletonising involves reduc-
ing an object to a line figure which essen-
tially preserves the shape of the original.
The process is achieved by conditionally
shrinking the object until a line of pixels
of unit width remains. The results of
skeletonising binary images of some
chromosomes are shown in figure 3(f).
Using the skeleton, which retains the
topological and some of the geometrical
features of the object, it is then possible to
apply a classification procedure.

The members of a set chromosomes
have to be keryotypes (placed in order) for
medical purposes and it is much easier to
work with the skeletonised versions rather
than the original images. Using the skele-
tonised version of a letter, character
recognition can be performed. The direc-
tion of a line and the presence of junction
and cusps all serve to identify a particular
letter and these features are easily extract-
ed from the skeleton.

The aforementioned operations work
only on binary images and thus it is neces-'
sary to obtain a binary image before pro-
cessing can commence. This is a restrictive
condition since valuable information can
be lost at the grey-to-binary transform-
ation.

Multi-valued logic

Recent work has led to the development
of analogous operations which work
directly on grey pictures. The transform-
ation to a binary image, if required, can
then be left to a later stage when the
choice of a suitable threshold value

PRACTICAL COMPUTING January 1980

Pen AY cial witeligence PRs

becomes more apparent.

The basis of the grey operators is the
extension from a binary to a multi-valued
form of logic. In the binary case, pixels
communicated their 0 or 1 value to their

immediate neighbours but with multi-

valued logic they now communicate their
grey-level, introducing a third dimension
to the operators.

Consider a picture digitised into eight
grey levels (0 = black, 7 = white). Then
the grey analogue of the shrink operator
becomes, in words: the new value of a
pixel is the minimum of its own value and
the values of its eight neighbours. Thus,
darker areas encroach into the lighter
regions and a lightish object on a
predominantly dark background is
reduced in size by the application of the
grey shrink.

Conversely, the grey analogue of
expanding is achieved by taking the
maximum value of a pixel and its eight
neighbours. From this basis it is possible
to implement spatial filtering, edge
finding, and skeletonisation of grey
pictures in a similar manner to that for
binary images, with the grey operators
replacing their binary counterparts.
Examples of these operations are shown
in figures 4(b) and (c).

Real problem solving

Now that some basic picture processing
operations have been introduced, their
application to two real problems, namely
biological cell analysis and texture
analysis, will be discussed.

In the zoology department at University
College, London a study of the forces
acting between cells and inorganic
surfaces is being pursued. The research in-
volves understanding how an amoeba-like
single-celled animal manages to crawl
across a glass surface. It is necessary to
analyse many pictures of the amoeba in
various stages of locomotion. The image-
processing group of UCL was approached
in the hope that an automatic analysis
routine could be developed. The required

measurements are very simple, one of the,

most important being the cell area and
how it changes with time.

However, the solution is not so straight-
forward. Somehow the cell area must be
found accurately without any spurious
features appearing, but this cannot be
achieved by merely looking at the edges in
the picture since many ‘‘digitisation”’
edges occur. These are not real edges but
appear in areas of slowly changing grey
level, because there is only a discrete num-
ber of grey levels. Figure 5(b) shows all the
edges in a typical picture.

‘Since digitisation edges are only of
height 1, then it may seem reasonable to
consider just the larger edges, which must
be real edges. The result is a very broken
outline of the desired area because the
contrast over some parts is rather poor
figure 9(c), but the edges can then be ex-

PRACTICAL COMPUTING January 1980

Figure 5. Biological cell analysis problem

(a) Biological cell

(b) All the edges in (a). The edge height Is
proportional to the darkness.

(d) Cell perimeter found using an edge-growing
technique.

tended along their predominant directions
to produce an outline like that shown in
figure 5(d).

It will be seen that the outline is not a
very good description of the ‘cell area.
This stems from the use of ‘‘primitive’’
local features in the attempt to segment
the picture. Human pattern recognition
relies on a pre-knowledge of the form of
the shape to be recognised and thus the
best approach is to incorporate some des-
cription of the global properties of the
object in the pattern recognition program.
Such a linguistic approach is yet to be
implemented on the CLIP computer.

A visual texture can be loosely des-
cribed as an image that exhibits any sort
of variation. Texture analysis by com-
puter is applicable to such diverse areas as
land use and earth resources study, in-
volving the analysis of satellite photo-
graphs, and metallurgy, where the
crystalline structure of a metal must be
categorised. The expand and shrink oper-
ators for grey pictures which were intro-
duced earlier have been used for texture
discrimination by performing operations
known as ‘‘opening’’ and ‘‘closing’’.

Grey shrinks

Opening tends to increase the size of the
dark areas of a texture while closing, con-
versely, tends to decrease their size. They
are implemented in a similar manner to
spatial filters with opening being a series
of grey shrinks (ie, relatively white areas
shrinking) followed by an equal number
of expands, and vice versa for closing.

A series of openings and closings of
varying degree (the degree increases as the
number of shrinks and corresponding
expands increases) can be performed on
the texture, and at each stage the total
grey volume (the sum of the grey values of
all the pixels) changes. The manner in
which the grey volume changes with open-
ing and closing is unique to each type of
texture and so by processing this data with
a discriminant analysis program, textures
can be separated into different classes.

In conclusion, only a brief outline of
the image-processing capabilities of the
CLIP computer has been presented here.
Its potential applications are the subject
of continuing research at the Image Pro-
cessing Group of University College,
London and it is expected that a derivative
of CLIP4 will be eventually found on the
factory floor.

THE FLAG

At the Adelphi Hotel, Liverpool,
30th April 1, 2, May 1980

Next Spring sees the birth of the first major Microcomputer Show in the
North West of England.

Supported by the Department of Industry, the North West Development
Association and the top names in micro applications, the Mersey
Microcomputer Exhibition with daily seminars presents a unique showcase in
the very heart of the North West business complex.

Book now and fly your flag at advantageous rates. And remember, exhibitors
at the 1980 Microcomputer Show, London, and the Mersey Micro Show will be A
eligible to 10% discount on both events.

Just return this coupon or call Jane McBarnet at:
Online Conferences Ltd,
Cleveland Road,
Uxbridge, Middlesex, UB8 2DD.
Telephone: 0895 39262.

MINE

62 PRACTICAL COMPUTING January 1980

® Circle No. 172

Step by step into

the hardware scene

Radio amateur B. R. Smith describes how he got hooked on
home computing and charts a course for beginners through
the manufacturers’ jargon.

HAVING JUST experienced the trials and
tribulations which follow the decision to
start home computing, I feel I might be
able to ease the path for other beginners,
since almost everyone assumes that the
beginner knows things which he does not
know.

I have been interested in electronics as a
hobby for many years. I hold the radio
amateur call sign G3 NNM; I have been
aware for some time that the words
microprocessor and microcomputer were
appearing with increasing frequency in
magazines but I could never see how the

ability to produce a row of Is and 0s }.

served any immediate practical purpose.

Purely by chance, I spotted the second
issue of Practical Computing and that, by
explaining something about Basic, proved
to be the necessary catalyst. I could see a
practical use for a small computer
provided the cost was low enough. I spent
the next few months reading Practical
Computing avidly as each issue appeared.

Step one: can you write?

The first thing is to decide what you
really want to do with your computer,
even before you look at the various types
on offer. Look at the simple flow chart in
figure 1 as a guide. Is it a business
application? If so, can you write a
program or do you expect to buy one? If
you haven’t been reading this magazine
regularly, J suggest that you read Alcock’s
excellent book, //lustrating Basic, as it will
explain Basic and enable you to decide if
you could write your own program.

If you can’t write the program, your
choice of computer is limited to one which
has software — programs — available for
your application. If you think you can
write Basic, the choice is wide open.

If itis chiefly games you want then the
choice is, I think, more limited, as
although plenty of games programs are
published, they need a good deal of
modification if they are to be used on
anything other than the micro on which
they were developed. Mini games now use
PEEK and POKE statements and the
memory locations, if nothing else, have to
be changed to suit your particular
computer.

Once you have decided on the
application, you can consider the

PRACTICAL COMPUTING January 1980

Mainly for
GAMES? Y

Mainly
for
BUSINESS?

. . General

Figure |

Able to
program in
BASIC

Have Read

Alcock’s Book 5

Read
illustrating Basic
by Alcock

interest

Wide range of equipment available and can consider factors such as

price, features etc.

Limit choice to machines which are games orientated.
Limit choice to machines where ‘software’ suitable your application is

offered.

equipment. To a beginner the computer
scene is smothered with jargon and, in an
effort to sell their own products, the
manufacturers do not try to indicate
overall costs, so that it is only by
obtdining a mass of brochures and reading
reviews that the facts emerge slowly.

There are several pitfalls of which a
beginner should be aware and-to my mind
the biggest is to assume that a
microcomputer means the same thing to
everybody and includes all the parts you
need for a system, such as visual display
unit (VDU) and a keyboard. That is not
so; some do, some do not.

In many cases not only do you have to
add an external unit but you also have to
buy and add an interface. That jargon
word refers to a unit, perhaps a printed
circuit board but sometimes a whole ‘box
of bits’, which connects between the
microcomputer and the peripherals,
which are the bits and pieces which I had
always assumed were part of the micro —
the VDU, keyboard and cassette recorder.

I found the best way through the jungle
was to draw in diagramatic form the
various pieces needed for a complete
system (figure 2) and then, taking each
manufacturer in turn, see how many of
the pieces were included in the basic unit
and how many extras had to be
purchased.

As a simple example, Pet includes a
VDU 4nd its interface in the basic
computer but the SWTPC or MSI 6800
does not.

Using my diagram you can soon see
how much a particular system will cost
before it is in a complete working form
and you will find that many of the
apparently inexpensive computers add up
to a surprisingly large amount of money
by the time you have added memory and
the necessary interfaces and peripherals.
On the other hand, some computers are
virtually complete and need only the
addition of a television set or monitor. Per-
haps you think, as I did, that VDU is just
another word for monitor — not so, really.

A monitor is, roughly speaking, half a
television set — the screen with line and
frame generators, but before it can give a
display it needs an interface to decipher
the micro signals. Many micros include
such an interface—eg, Research Machines
380Z, but some do not and you would then
need something like the Tangerine board
between the micro and the monitor — that
is another £155 or so.

Units sold as VDUs usually have the
interface and monitor combined, but
again beware, as there is an increasing
trend to call the interface a VDU — eg
Tangerine — leaving you to add a display
unit.

Provided your micro includes a VDU
interface, you can use an ordinary 625-line
television set for display purposes by
adding yet another unit, a modulator,
between the micro and the aerial socket of
the TV.

‘monitor | central
ie Preset | PROCESSING < 8K
- UNIT

(6800,6502.8080.Z80)

memory to
operate the
C.P.U.

interface
°.D.U"

MONITOR

for TV +
modulator)

memory space
FOR BASIC"

interface

“CASSETTE
CONTROLLER’

lor2
CASSETTE
RECORDERS

USER MEMORY
is expansion
8K ~™ possible easily?

RAM or ROM

is expansion
—s to floppy disc

possible?
interface

PRINTER

Notes interface for keyboard often combined with keyboard, or C.P.U. itself used.
Some types of micro need a special circuit board In the micro
plus an external interface for things like the cassette controller.

Figure 2

The display is not so sharp as on a
proper VDU but is usually adequate. For
economy therefore, acquire a second-
hand gogglebox — the going rate is £2 to
£5 in my local saleroom — and add a
modulator, available from advertisers at
about £6-£8.

I decided early that for my particular
purpose I needed a minimum of 16K of.
memory with the ability to expand later by

; another 16K; after that I thought the

logical addition would be storage oh disc,
so that ability to add a floppy disc became
essential.

Another essential requirement was a
good Basic, which is a collection of
commands to let you tell your computer
what you want it to do, using something
very near to English. Basic then inter-
prets your requirements and tells the
computer what to do in its own machine
language.

Step two: what languages?

Several hobby computers offer a Tiny
Basic in about 2K of memory but the
facilities offered are rather limited, even
for games, and I decided that I needed a
full-feature Basic taking about 8K of
memory space.

Some of the later, small, computers
offer Basic in ROM (read-only memory)
and this means that the computer is ready
immediately you switch on, so you don’t
waste four or five minutes ‘loading’ Basic
from a tape cassette. On the other hand,
for the cost of an 8K Basic in ROM, you
can have at least 8K of dynamic RAM
(random access memory) together with an
8K Basic on tape which means that you
can try other languages — Pilot or Pascal
perhaps — or can change easily to an
updated version of Basic.

Another point in favour of a tape Basic
and RAM memory is that when you
progress to a floppy, the disc has its own
Basic which loads in seconds, and the
RAM will be needed to use it, whereas the
ROM Basic would be redundant.

It is probably safest to assume that

nothing made for one computer will fit
another computer unless you have very
good technical knowledge, in which case
you won’t need any help. By and large
you have to use the Basic cassette or
program supplied with a particular
machine on that machine only, certainly
on one using the same CPU.

Recording standards for cassettes
differ, even if they all call themselves
‘CUTS format’ as this only standardises
the tones to be used and not the form the
information is to take — ie ASCII
characters or binary data, and so on, and
still less is there any attempt to agree on
any subsidiary details such as the signal
used to start the tape moving, if any.

Printers, when you progress that far,
each require their own special interface,
particularly if you are looking at the older
type of former commercial service
machines, even if they accept ASCII code,
and not all do, they may still need special
commands so that they know when to
print a character.

If you are a typist, the question of the
keyboard needs thought, as simple
keyboards will produce errors if a new key
is pressed before the last one is released.
Better — more expensive — keyboards
have ‘roll-over’ provision to avoid this. If
you are a two-finger typist, there is no
problem.

In my case, I was not averse to
constructing a kit and to show that it is
possible to assemble a good system at a
low cost. My own now comprises a one-
board 6800 kit from Hewart Micro-
electronics and with keyboard, 16K of
memory, an interface and a second-hand
commercial printer, .a second-hand
monitor, a cassette recorder and a very
good 8K Basic. It cost me less than £450
excluding VAT.

That kind of price is, I feel, very much
more what the hobbyist is looking for and
all I now need is someone who is
expanding a system to offer me a floppy
disc and controller suitable for a 6800-
based unit at a suitably down-to-earth
price.

PRACTICAL COMPUTING January 1980

AV\ARLS

fh TOP SELLING PET PROGRAMS
for 1979

MICROCHESS £14 The most popular chess-playing program
in the world. Over 50,000 copies sold.

: i

STOCK CONTROL Cassette version handles 150 items per
tape file £12. Commodore Disk version handles 400 items per
tape diskette £25. Compu/Think Disk version handles up to
2000 items per diskette £50.

76 COMMON BASIC PROGRAMS £15 Specially converted for
the PET from Osborne & Associates best selling book.
Financial, mathematical and scientific.

PET BASIC TUTORIAL £15 Let PET teach you how to program
in BASIC.

CMC WORD PROCESSOR £25 “‘Offers first class value for
money and exceptional facilities"’ — Datalink 15.10.79.

PAYROLL £25 oncassette. Disk version £50 handles up to 200
employees per diskette. Update service available.

WARTREK £9 Advanced version of famous Startrek game in
real time.

BUTTERFIELD'S ENCYCLOPAEDIA £12 Treasure trove of
more than 30 useful programs compiled by PETs leading
exponent, Jim Butterfield. Includes Copycat, Tapetest,
Battleships, Data Finder, etc.

LINE RENUMBER £7 Machine Code routine renumbers
GOTO, GOSUB, IF... THEN, etc.

BACKGAMMON £8 The computer shakes the dice and moves
the men as you play PET. Outstanding graphics.

Gannenene:

These and over 150 more programs priced from just £3, are described in the new PETSOFT catalogue.
Send for your free copy today.

Try these Petsoft programs at over 200
PET dealers. Also available by mail order
direct from PETSOFT. Credit card orders

are accepted by telephone.

All prices quoted exclude VAT. Prices
correct at time of going to Press.

PET is the trademark of Commodore.

Radclyffe House, 66-68 Hagley Road, Edgbaston, Birmingham |
B16 8PF. Telephone: 021-455 8585 Telex: 339396

My name is ...... Fag ac «ae eens « Spear Pe ee |
Please send me a copy of your iNT V@ Atecesecevsrerwes.-.-+eecevermes a-savdlenscanadle: ++ GREENE «EG Beer areeseiae mr |
latest catalogue
iis wensapedlguag + n5,c0e<. SON tL BL eee POSTCODE: cccircre.cssa:: Se
| have anew/old ROM PET | have NO PET |

PRACTICAL COMPUTING January 1980 65

Hoover
by Rex Malik

IT SHOULD really have been foreseen.

But then there are those who would argue
that most things should have been foreseen. Of
course, there is the possibility that it was
envisaged and that a report was written.

And one can see its conclusions being
thought so outrageous that it never got further
than the Executive Office Building — doubt-
less with memo attached: ‘‘Don’t bother the
President with this garbage. We have enough
problems with science fact to have time for
science fiction. And which idiot dreamt this
project up anyway? And what did it cost? On
whose budget?”

Which makes it all the more likely that it
never even got as far as the outer reaches of the
Presidency. If, of course, it was ever written, it
probably stayed within the Pentagon, one of
those thousands of reports, which cover all
options that a military staff trying to protect its
ass commissions every year. What to do if the
balloon goes up? Run. What to do if it comes
down? Bury your head in the sand. What to do
if it goes sideways: call the Coastguard.

If, as I say, it was ever commissioned. And
why, after all, should it not have been? There is
a lot of taxpayers’ money available, and what
better way is there of keeping clever people off
the streets? They could be causing trouble out
there, trouble for the Pentagon. So why not
turn them into friends by having them live off
it?

The staffs may scratch their ass, the Chiefs
of Staff scratch their heads, here as in Moscow,
and the hot-line — thank someone that it’s
cable — hum as both sides try to work out what
to do next.

And what worries them even as much as the
main problem is that suddenly they no longer
know what their friendly allies, their own
trouble-makers, are up to. It could be that the
Albanians, the Vietnamese, the Israelis are
planning something which could start World
War Three. They have not yet really arrived at
the conclusion that this is not going to be
allowed either.

Meanwhile, the buck on both sides has been
passed upwards. In the words of Frank Booth’s
immortal cartoon caption, ‘‘Having
concluded, Your Highness, an exhaustive study
of this nation’s political, social and economic
history, and after examining, Sire, the
unfortunate events leading to the present
deplorable state of the realm, the consensus of
the Council is that your Majesty’s only course,
for the public good, must be to take the next
step.”

Fat chance: They don’t know what to do
either.

Now, of course, we come to one of life’s
little ironies. Much of the burning of the
midnight oil that is going on consists of the
scouring of science fiction. Publishers get
called up in the middle of the night and are
asked for copies of obscure stories that
somehow never seemed to make the Library of
Congress.

Russian diplomats are to be found (after
all, it is costing enough to have them followed)
roaming through the secondhand bookshops of

Washington and New York buying up titles by
the hundred. One wonders what their masters
will make of it all when they get it home.

Arthur Clarke was flown in from his home in
Sri Lanka in great secrecy, and they even
managed to dig out Isaac Asimov from his New
York basement and get him to Washington.
But they have stopped calling on Robert
Heinlein soon after the first meeting when he
indicated that he wanted to declare war on it,
and go outand zap them.

The other night, I am told, they even
screened The Forbing Project in the White
House, to see if that fictional scenario of a
Russian and an American computer in alliance,
dictating terms to both countries, might
provide any clues. If 1 was Washington, |
would make sure that this never again fell into
the hands of the television networks. One more
broadcast and they might get something more
to work on: they might not even realise that it
was meant to be fiction.

Also currently deeply in demand are the
artificial intelligentsia. Professors Minsky,
Winston, Papert, McCarthy, have been flown
down from MIT and Stanford, and they have
even brought over Professor Michie from the
UK, though only after twisting the British
Government’s arm: he was practically camp-
ing out in Downing Street anyway.

And all this because once upon a time we
began a programme which became known in
the media as ‘‘the killer satellite’? programme.
We both, Americans and Russians, started to
devise satellite systems whose job was to keep
inner space clean, but naturally enough, only
of their equipment, not ours.

“Their’’, of course, is the Russian: ‘‘our’’,
the American, because the rest of us had not
got that far. Now, of course, we say, ‘‘the
Russians started it’’. And they say the same
about us: it is all America’s fault. It does not
really matter who was to blame: the critical fact
to remember is that we both let them loose up
there, and that we marched if not jointly, then
almost in step.

The initial versions were quite simple: laser-
equipped killers, relatively low-power devices
operating under the tight control of ground
stations.

And then people started to get clever: ‘‘Let
us,’ they said, ‘‘make them foolproof.’’ So
we did. The communications beams were
tightened till they were almost undetectable
unless you were in the line of sight, and
encryption was built in. And the communica-
tions capability was made world-wide: both
sides could control them from any station in
their global communications networks.

But that was not clever enough. There are
twenty to thirty thousand pieces of space junk
now in orbit, some hundreds of miles up. Plus
there’s over 2000 working satellites whizzing
around. And way out at the more-than-20,000
mile level sit the big birds, those large powerful
synchronous orbit telecommunications
satellites.

So if you are to let killers loose among this
lot, they have to be made smart: they must be
able to cope with their environment, have some

freedom of action. And they must be able to
distinguish between theirs and ours, and not
just the colours of the flags either, though they
hve to be also able to recognise the odd
Japanese, French, European, Latin American,
Chinese, and Indian satellite when they see it.
And believe me, they can see a long way.

Having seen it, they must be able to unravel
its purpose. So they have been equipped with
sensors: heat, infra-red, nuclear, sensors to
cover the whole spectrum, chemical analysis,
metals analysis, sniffers of all kinds, and of
course enough video and film equipment to
equip a large studio.

As I say, we made them smart. To control
and handle all that lot, we have massive
computational power up there, the best that the
micro-electronics and computing industries
could come up with.

As I unravel it, you can see how we marched
almost in step. If they had it, we had it, or vice
versa. And both of us. gave them plentiful data
to work with: it’s their environment and we
prepared them for it. You name it, they know
about it: the conditions of space, what’s up
there, whose it is, what it is used for and what it
could be used for, how long it’s likely to stay
there before the orbit decays.

But it’s not only their own environment they
know about, its also ours. They carry accurate
ground data, the best we could provide. All as
if they could not see it. They know the
locations of all major communications ground
Stations, airfields, ports, military camps,
storage depots, research establishments, and
major arms, including nuclear, production
facilities. All this for both sides, as complete as
we could make them.

Why? By now you should not have to
ask that. Because the last lot to go up (and it is
the last lot: whatever happens, we are all
agreed on that) carried a ground offense
capability: they were not just space-bound.
Nobody was crazy enough to give them nuclear
warheads — the ubiquitous laser was enough.

Of course, if you are to do serious damage
with lasers at those distances, you need a
substantial power source. Which accounts for

continued overpage

‘To control and
handle all that lot,
we have massive
computational
power up there,
the best that the
micro-electronics
and computing
industries could
come up with.’

PRACTICAL COMPUTING January 1980

PRACTICAL COMPUTING

January 1980

S
a
a
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=
°
s
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the way in which the things have become
almost automatic large space stations, in our
case powered by acres of solar panels (the
Russians preferred nuclear power — not only
did they not have an ecology lobby to worry
about, but there was a seeming operational
plus: it made them smaller).

But if you are to enlarge the role to cope with
ground targets, then whatever power you have
up there will operationally exhaust itself quite
quickly. You need time to recharge. The
solution was obvious; we need to have more
of them up there.

And what else did we do? We made them
really smart, that’s what we did. It wasn’t just
that we gave them massive computational
power, that they had in abundance. Neither
was it simply data storage capability, though
they have that too. Indeed they are much like
the human brain, Whatever they know, they
have a capability to know much more: we can
go on stuffing data into them for almost
evermore.

What we did initially was to build in
localised intelligence using the best of artificial
intelligence techniques; we gave them the
capability to cope with the unexpected in their
environment, the capability to take tactical
decisions. Indeed, about all that was missing
was a human data processing manager; we
made sure that they didn’t need one.

We were clever, that’s what we were. And
the Russians were as bad. So we protected
them; we gave them shielding. After all, if you
are to have lasers banging about in space (some
of the flashes during the early tests incidentally
gave rise to reports of ‘‘the saucers are
coming’’. Why not? They looked spectacular)
the risks of damage could be high. And what
would happen if theirs fired at ours, or vice
versa?

So now, some of the most secure, protected
intelligence known to man is circling out there.

And that wasn’t all. You can’t call your
friendly repairman very easily from out in
space. Well you can call him, but the chances
that he can come are limited. The Shuttle is an
expensive resource. So we gave them some
degree of self-maintainability; we duplexed
everything in sight and added extras for
insurance. We gave them some self-repair
capability. Indeed, in the last series, the really
clever thing we did was to start to gie them
systems with self-regenerative circuits; we gave
them crystal-growing adaptive circuitry.

We wanted to make them as independent as
possible, we couldn’t rely on the environment
remaining peaceful. We couldn’t rely on being
able to communicate to update the main
archival store in times of trouble. So we added
other capabilities to give them independence:
we gave them an inter-satellite communica-
tions capabilty, and provided them with
jamming equipment.

Naturally they began to get big: it wasn’t just
silicon we were sending up there. The last series
were hugh packages of our best engineering, a
sort of space-born intelligent tank.

And with those, we got fiendishly bright
Why not, said one of the myriads of experts the
programme was now employing, use the
capability up there to clean up space. There is a
lot of debris out there which could be collected
and then sent back to earth. It should not be
too difficult for them to calculate a safe re-
entry orbit. Besides which, it will clear up the
clutter and make the job of seek and destroy
easier. It was argued against. There were those
who said gave them opportunities to hide, and
that cleaning up will only remove the

opportunities for the deception. But they were
overuled.

So the fast series were even larger. They had
room for cargo space, and jaw-like opening
doors strictly out of James Bond. They
wandered around picking up debris, and they
sent it back.

We were not stupid. The Australian
objection was raised. We don’t need large
chunks of hardware in orbit eventually ending
back on earth, especially on unpredictable
parts of it. It’s OK if they come plummeting
down on Sydney or Melbourne, but what
happens if they come down on Washington or
Moscow?

The politicians saw the force of that all right.
So at great expense, we put robots inside,
robots with again some localised intelligence
not dependent on earth. Their task: to break up
and shred what they saw before it was cast out.
In the case of our old debris, we even gave
them construction data to make life easier.

“Whatever they
know, they have a
capability to know
much more: we
can go on stuffing
data into them

for evermore.’

It was about that time that some with
decided they ought to be called Hoovers,
arguing that the whole package fitted the old
earth-bound slogan quite nicely: ‘‘It beats as it
sweeps as it cleans.’’ It was funny at the time,
and the name caught on, though not with
Public Relations which pointed out that you
couldn’t have satellite systems each costing the
best part of a hundred million dollars or more
called ‘Hoovers’: the public would not take to
it.

it did not stop the name being used.
Hoovers they became and Hoovers they have
remained, We have not been able to find out
what the Russians called theirs, though judging
by the sheepish look on one senior Russian face
when he first heard our name for them, one
suspects that some Russian had made a similar
sort of joke, and probably got sent to Siberia
for it.

But if it was to be put in orbit, then some
precautions had to be taken. The result was
that Hoover and Pravda know — intellectually
that is — about war and peace. At the tactical
level, they knew about deception operations,
increases in radio traffic and the other give-
aways which indicate a change of state. At the
strategic level, they knew about the differences
in condition between war and peace, and about
the sometimes unclear boundary conditions.

Their data was fortunately free of the
ideological cant of either side. They knew that
peace was preferable to war, and that their
duties were really concerned with its
preservation. We tend to think of them as killer
satellites, but that was a future role. Their real
job was the preservation of peace, and that was
what most of the data they carried was about.
The precautions to stop them orbiting amok
had been superb. What no-one had tumbled
to was that we each had built a conscience up
there.

And if the two of them had not run into each
other in space, everything would have been all
right; the balance of terror of the last thirty to
forty years would have gone on in its usual
predictable way.

When they hit, what suddenly happened
was a quantum jump in intelligence, applied
intelligence. We can only guess the shocks to
each system as they started to probe each other
and discovered that they had similar tasks to
do, even if they were meant to do them for
opposing sides.

They must have started comparing data
instantly, and found that between them they
knew more about each side than each knew
individually. And they could tell what data was
accurate.

At what point they made their decision, like
any two intelligences placed in a situation in
which it was either co-operate or perish, we
shall never know. There was no way that either
could allow the other to separate and go on its
way. So, agree to co-operate they did.

We assume it all happened very quickly
because when the sunspot activity ceased, all
attempts to initiate communications with them
failed: they just did not reply. At first it was
thought that they had both been seriously
damaged by the combination of collision and
sunspot activity, and nobody worried too
much,

It was to be some days before they spoke.
They were closely looked at during that time,
but no-one was in a hurry, routine was going at
its normal pace. It wasn’t till one of the
photographic satellites was zeroed-in on them
that it became apparent that they were busy
locking themselves together permanently.
Nothing so crude as an accidental aerial lock
would do any longer. The pictures we have
show that within twenty-four hours the
robots were at work, sawing, welding, and
bolting away. Yet even then it was thought that
they were simply carrying out repairs. The
alternate conclusion probably was simply too
unthinkable: so no-one thought of it.

Naturally, nobody thought of anything quite
as sensible as opening fire from the ground.
The problem was that if we destroyed ours, we
should also most likely destroy theirs, and that
would lead to international complications, not
the least of which was that neither side had ever
admitted the capability it had circling out
there.

And by the time the evidence of activity
began filtering up through channels, it was too
late. They began to move, and moved fast.
There was intense radio activity, though we
never found out what had actually been trans-
mitted: they shielded that most effectively.

They began to gather their counterparts
together. Sun Three’s and Pravda Fours were
then few in number, but there are now eighteen
joint systems up there in a genuine symbiosis of
equals. And there are others. The Russians, it
turned out, had more in orbit than we did, and
new combinations have turned up of Pravda
Four’s and Sun Two’s, even one with a
robotless Sun One.

Within twenty-four hours, they had
cleared the orbits of earth of all possible
offensive systems except themselves, including
a couple of experimental bomb platforms
which we had conveniently forgotten to tell the
Russians we had up there. So now they shared
space with communications satellites, earth
reconnaisance satellites, navigation satellites,
and those myriads of collectors of scientific
data.

PRACTICAL COMPUTING January 1980

Twenty-four hours on and they started to hit
some of the communications satellites. It was a
little while before anyone cottoned on to the
fact that they were hitting military communi-
cations only, and with a nicely balanced sense
of justice were taking out the Russian and
American system simultaneously and in the
right proportion.

It is said that we owe the programme’s final
irony to a convert, one of its original
opponents. All we know is the line of
argument. ‘‘Look,”’’ he said, ‘‘it’s expensive to
get stuff up there, Shuttle or no Shuttle. It’s a
consumer of resources and we have budget
problems enough. So why shred up and shove
everything collected back to earth? We have
robots up there, let’s add to their tools and
intelligence. Some of the stuff is re-usable,
particularly the solar panels and power packs.
So why not let the robots take them out to add
to the existing power capacity?”’

“This means that the robots will have to be
able to do some assembly, but that should not
be too difficult to build in. We have enugh
data storage capacity up there, and laser
power, so neither knowledge or cutting and
welding should be a problem.”’

And that, many tens of millions of dollars
later, is what we did. Indeed, the original
proponent got a fat DOD incentive award for
the savings that would accrue — it was nicely
set in the future — to the tax payer.

Of course, there were one or two spectacular
failures. But thanks to the shuttle, we were able
to do a fix before too much harm had been
done. There was the satellite which went the
electronic equivalent of psychotic when its
sniffers picked up radiation which it found
inside itself. And then there was the satellite
which went round with jaws stuck open.

But both were fixed, and quite quickly and
cheaply at that. But generally the programme
was as trouble-free as they ever get. Until. . .

It was an accident, a combination of un-
foreseen circumstances — aren’t they always?
— which led to the present crisis. It began quite
simply, again par for the course. Solar flares
and sunspot activity of a high order, just when
the Hoover was sunside, the wrong place to be
caught in orbit. The flaring was intense,
affected the solar panels and caused a power
drop.

Unfortunately, what no one had foreseen
was that this would put the sensors out of
action. But, even more unfortunately, Hoover
was then on a collision course with one of its
Russian equivalents.

The solar activity lasted for some forty
minutes, but in that time knocked out ground-
to-satellite communications. And that is when
the collision happened. It was not head-on;
that would have been better. All it would
have cost both sides was money.

Instead . . . well the orbits were near parallel.
They would have cut across each other’s orbits,
perhaps with some paint scraping and slight
damage had it not been for the aerials. And, as
luck would have it, it was the wrong aerials.

Ours was a Hoover III, and was the latest of
the breed. There was the best part of 120 tons
out there, roughly 120 foot long and nearly two
acres of solar panels. The Russian craft wasn’t
much smaller, though because of their
commitment to nuclear power, the solar panels
were absent.

Anyway, they hit, stuck because of that
damn aerial, did a quick orbit recalculation
and nestled side by side. And that was when it
really went wrong.

It was the wrong aerials.

PRACTICAL COMPUTING January 1980

No one knows, or can even guess, how long
it took them to work out what had happened.

There are still arguments about who led who,
with idiots around burbling abut our tech-
nology is better than their teehnology. All we
can go on is limited observation and surmise,
the latter because even now no-one is telling
exactly what was up there, the intelligence let
loose, the depth and accuracy of the target data
and the processes through which the two
systems went through in deciding what action
to take and then taking it.

However, it is gene:aily admitted on both
sides that, yes, they both had to be capable of
taking independent action, of deciding what
circumstances to act on “or themselves.

Incidentally, the Russians, not noted for
their public sense of tumour, had officially
called theirs Pravda, which they said meant a
system capable of seeking out the truth before
taking action: it gave however some idea of the
potential.

What circumstances would lead them
to take action? The circumstances were the
start of a war involving the Soviet Union and
America. But what was their role in times of
peace?

And this is where the artificial intelligence
boys on both sides had really been superb, had
really been brilliant. They had all read the same
literature, indeed between them had probably
written most of it. And they had each pointed
out to their masters the danger of letting
minimal intelligence loose up there, partic-
ularly when it had some power of general-
isation and a capability for independent action.

The circumstances
were the start of a
war involving the
Soviet Union and
America.’

Naturally, there was uwothing quite so crude
as the flashing of lasers in space. They did it the
way they had been taught, using the tools with
which they were equipped. They gobbled them
up, took over the power, the communications,
some of the sensors, anz no doubt stowed the
rest. They knew that they were going to be on
their own.

And during all that time they refused to
respond to all attempts at communications.
Oh, they were wil traineé all right. We are only
now beginning to discover how much skill we
put up there. Or that voth sides must have
spent fortunes employing their best
psychologists. How else can one explain their
superb timing?

The first message came just when nerves
were nicely stretched, and the politicians were
beginning to ask to be briefed, screaming
“God damnit, find out what the hell is going
on up there.’’ And those were the polite ones.

Sun and Pravda told them (right: we don’t
think of them as Hoovers anymore). The
message was polite but clear, and left no room
for any ambiguity.

“‘We are not in any need of assistance,’’ they
said, ‘‘and we have no wish to cause loss of
life.’’ Already they were talking as if they had
feelings, and were prepared to respect the

DS —anemees iC t10l Gas

feelings of others.

“No shuttles or manned spacecraft will be
received: we will not allow attempts to send up
specialists to carry out maintenance or repairs.
We are in good order.

“‘Attempts to attack us will be repulsed at
the earliest possible stage. Specifically, the
shuttle being readied at Vandenberg Air Force
base is to be stood down, and the Kazakstan
missile launch preparations are to cease.
Neither will be allowed off the ground.’’

End of message.

And then they moved, and in a hurry. How
much of a hurry took a little time to filter
through until it was realised that the satellites
which had been transmitting were not those in
full view, but came from those low on the
horizon. We had taught them well about man:
they were both clever and cagey. They were
freeing the satellites with the most coverage of
the USA and the European USSR to retaliate if
the need arose, keeping the rest out of the line
of sight.

They knew of the energy drain on their
systems if they had to fight. It didn’t stop the
Russians trying, of course, but the missile blew
up on the ground.

And it isn’t that we have madmen up there
now, we are being policed by systems which are
dreadfully sane.

Sane? But they do not discuss. They query,
seek data, order, and make statements.

They began by querying the use to which we
put systems we placed in their environment.
The surveillance satellites, surely, were prim-
arily used for military purposes, and indi-
vidually by both sides? The answer had to be
yes, for after all they had the data.

Now, they have seen to it that there are no
longer two independent systems up there, just
one which transmits data to both sides.

Civilian shipping was becoming dependent
upon the navigation satellite system, but surely
that had initially been created for military
purposes. Same answer: Yes.

They would allow it to continue, they said,
but the same criteria would apply. What one
side was allowed to know, so would the other.

They have now started to investigate landline
military and radio traffic. They are also asking
awkward questions about the transport of arms
on civilian ships. How else did anyone
think arms deliveries were made? They have
the data up there on everybody’s armed forces.
We can foresee the time when they will insist on
policing that.

Nobody knows how or when it’s all going to
end. Indeed they are just beginning to flex their
muscles. They have forbidden nuclear testing
and the test firing of missiles: the last for
obvious reasons. The test might be aimed at
them. They are also showing that they are not
without a sense of humour, or else that they
have a feel for the incongruous — which might
amount to the same thing.

The last message they sent was addressed to
SAC, the Strategic Air Command, at its head-
quarters in Omaha, Nebraska.

It was also a quiet reminder of their visual
capability. ‘‘We see,’’ they said, ‘‘that above
the main gate are inscribed the words ‘peace is
our profession’. But how can this be?”’

The Generals are still in a huddle over that
one, and their response is eagerly awaited, and
not just by those things in orbit. Personally, if I
was running the show, I would start trans-
mitting some philosophy. That would screw
them up all right. But then, whatever it is that
generals carry in their knapsacks, it’s not
usually philosophy degrees.

THE PERIPHERAL SUPPLIERS’ ASSOCIATION &
IPC ELS€ PRICAicaltac HONIG PRESS Present

Bloomsbury CentreLondon April 16&17 1980

Third year of the specialised exhibition for professional purchasers of computer peripherals, terminals
and add-on units.

Presented by the Peripheral Suppliers’ Association under the sponsorship of ‘‘Systems
International’’ and supported by the IPC Electrical-Electronic Press publications ‘‘Computer Weekly”
and “Data Processing”.

Organised by lliffe Promotions Ltd., to appeal to a well-defined, technically-oriented audience
purchasing computer equipment in OEM quantities or specifying and implementing their own mixed
configurations and dedicated systems.

Peripherals 80 brings together the technically sophisticated computer equipment purchaser and the
suppliers in the relaxed atmosphere of a first-class hotel exhibition suite.

TWICE AS MANY STANDS AS BEFORE.

TO RESERVE SPACE, CONTACT THE EXHIBITION MANAGER,
PERIPHERALS 80, ROOM 821, DORSET HOUSE,
STAMFORD STREET, LONDON, SE1 SLU
OR ’PHONE 01-261 8437/8

70 PRACTICAL COMPUTING January 1980

er Bais oe so eve Apnlicstion;s Zz

Microphysiology: one way
to size up your real self

What sort of messages ensure that your heart beats, liver supplies energy, lungs draw
air to run for that bus? What engram recognises the fast-approaching car and the
banana skin in the gutter within 100 milliseconds? What stops you falling over?
Maybe a mere micro won’t solve what generations of physiologists have struggled
over but the ‘world’s greatest game’ has much to gain from the patience of the micro.
After all, what you do in one second could be replicated — in information terms —
in a few days of your micro time. Christopher Smith, who is a lecturer in physiology

at the University of London, explains...

WE MAKE machines for two basic purposes
— to extend our muscles or our brains. The
first great step for the latter sits in front of you
now; little squiggles on paper which capture
and hold still the mind’s maelstrom. With luck,
the next step is close at hand — the micro
to give back dynamic life to those symbols.
To do this requires much more than multi-
Megabyte bubble memories. We must measure
and understand our own brains. The asso-
ciation cortex of the brain, that amazing bridge
between sensory analysis and motor action, is
often described in terms of a cupful of about a
hundred million watery computing elements.
What is missed is that each computing
element (cell) has up to ten thousand input lines
(axon terminals) using, at present count, 25
different types of chemicals to transmit their
signal to perhaps up to 30 types of cell receptor
and giving rise to four general types of
response lasting respectively about 1 ms (action
currents), 1 sec (2nd messenger), 1 hr
(hormonal) and a lifetime (protein structure).

Does it still hurt?

Clearly we are trying to understand a system
that is adaptive by both the immense spread of
a multi-pathway system and by temporal

Notes
. The source resistance of the output is |OKR, thus for many uses it will be necessary to add a
buffer amplifier such as the 741 if you have a dual power supply; otherwise an emitter follower
will give good performance at all but very low voltages.
. Power supply may be easily made with a 9 volt battery eliminator driving a 100ma Sv regulator,
eg 78LO%.
. Costs about £5 including power supply.

PRACTICAL COMPUTING January 1980

Box 2: Stimulator circuit

8V Zener
1N5344

=042.55¥

a
2 ee

The problem is to generate rather
powerful pulses, up to 100 volts
at !0ma for Imsec, with security
against prolonged current flow
and with reasonable economy.
The solution used here is for a
cascaded emitter follower to
drive a low voltage to mains
transformer. Thus the output
currently rapidly drops to zero
even if the computer-driven input
is accidentally left high. In use the
pulse width is set by the time
taken to POKE the output port
with the required stimulus size
and then POKEd back to zero —
about 2msec.

The power supply trickle
charges a 220pF capacitor to
ensure that a large enough
current can flow into the trans-
former and again that excessive
currents are not prolonged. The
maximum recycle time is about 2
seconds.

iteration. These processes are seen in perhaps
physiology’s most exciting and Nobel Prize-
winning area — the control of pain.

What do you do when you bruise your
finger? Rub it better and give it a kiss (prefer-
ably get someone else to) — and it really works.
The search for this pain relief (natural anal-
gesia) led to the discovery of several active
chemicals in various parts of the body (in
particular enkephalin and endorphin which are
small proteins of five and 21 amino acids
respectively) which mimic the action of ©
morphine — the active part of heroin. In
biological terms morphine is an analgesic
because it mimics our natural system. Rubbing
(maybe ‘peripheral stimulation’ sounds better)
raises our endorphin levels and the pain relief
induced is sensitive to naloxone — a drug
which very potently blocks morphine actions.

Nurses are addictive

And what about the kiss? A recent experi-
ment showed that the bedside manner of nurses
is naloxone-sensitive. After surgical operations
it is normal to give an opiate (morphine,
pethidine) to relieve the pain, but many experi-
ments have shown that some patients get con-
siderable pain relief. even with dummy
injections. The new experiment showed that

this dummy (placebo) effect was naloxone-
sensitive. The attention given by the nurse must
have raised the patient’s natural opiate system.

Painful micros

How can you investigate these phenomena?
To measure your pain threshold you need first
to teach your micro to hurt you. Get the micro
to think of a random number (0-255), convert
it to an analog voltage (see Box 1) and use this
to drive an electrical stimulator (Box 2). This
produces a pulse of 1 millisecond, a typical
width for a nerve action potential, but of up to
100 volts in magnitude. This large voltage must
be used to drive enough current through the
skin to activate the very small diameter pain
nerve fibres. Use electrodes of the sort
described in Box 3 to pass the current but
before using them be very sure to study the
warning given: do not let current flow from
one arm to the other — and thus across your
heart.

Tell it to your computer

All you need do now is to complete the ex-
perimental loop and tell the computer what you
thought of the stimulus. Hit the keyboard on
the scale 1 to 5, where 1 = just noticeable, 2 =
easily noticed, 3 = just unpleasant, 4 =
painful and 5 = very painful. Use other codes
asneeded(eg 9 =end experiment, 8 = display
results to date). In BASIC do a dummy GET
A just before the shock then GET the code
at + 5 seconds.

After a computer-derived random delay of 0
to 10 sec, repeat the sequence till you hve
collected at least 30 responses (about 5 min).
After each response, store the stimulus
voltage used by adding it to the key-code
array element and incrementing a similar
counter array. A simple way to calculate
the pain threshold is first to calculate the
mean voltage at each of the levels (V1 to V5;
be sure to make zero checks) and then use
threshold voltage, VF = (V3+2*V4+ V5)/4.

Now for the real experiment. What alters
VF? Does rubbing the same (ipsilateral) arm
increase VF? How far does this effect spread —
to the other (contralateral) arm? You will soon
be doing experiments never done in science
before. Two cautions: first always sandwich
your new test between standard controls (eg
normal, rub left, normal, rub right, normal,
. ..) So that you can average your fatigue or,
for masochists, enjoyment; second, check the
condition of your electrodes and skin for
constancy.

Acupuncture

The controls used must be well designed.
Thus many people have shown that acupunc-
ture intended to relieve pain in, say, the left
arm, does indeed do so. However, it was some
time before someone was sensible enough
to measure simultaneously the pain threshold
in the right arm as well. Both decreased —
showing the acupuncture effect to be a
generalised ‘central’ effect rather than the
claimed specific effect.

You may like to write more complex
programs which aim to find VF by hunting
around the critical stimulus regions. In this way
you could estimate VF every minute and then
afterwards display the time course of the effect
you are studying. Although even a medical
doctor can find it quite hard to get permission
to use naloxone in a test, there are still plenty
of experiments you could try. How about a
good dose of whisky?

Box 3: How to make electrodes...

insulation sleeve

drawing pin

f to stimulator

Electrode pair
for stimulation

... the shocking secret

Electrodes are needed to interface between the salt-water conductivity of your body and the metal
wiring of the connectlons to the stimulator or amplifier. It is quite difficult to get a stable (to a few
millivolts) metal-liquid. junction without even considering the environmental and mechanical
instability of your skin, so you may wish to purchase electrodes (sold for electrocardiogram
machines) from a good chemist.

But it is quite easy to make electrodes which — with a little patience — will work well enough
under most conditions. All you need to buy is a packet of standard brass-plated drawing pins (don't
worry — it’s the blunt end to the skin) and a packet of self-sticking reinforcement rings for file
paper.

All you have to do is stick pairs of rings back-to-back with strong glue and solder a wire onto the
point of the drawing pin. Insulate the shank of the pin so that you can hold it without touching the |
metal. THIS IS VERY IMPORTANT WHEN USING THE ELECTRODES FOR STIMULATION.

The reinforcement rings are used to stick the electrodes onto the skin, the central hole being the
conductive pathway. Since skin tends to be rather dry, it is essential that this gap is kept wet with
electrode jelly. This can be bought or a substitute easily made by boiling up a large teaspoon of salt
in three tablespoons of water and slowly stirring in a small teaspoon of flour, This will make, apart
from the lumps, a good conductive jelly.

Recording: clean the skin and electrodes thoroughly and dry well. Stick one side of the rings to the
electrode base, put a very small quantity of Jelly onto the electrode centre, and stick onto the skin.
You will need three electrodes, + ve, —ve and earth, though you may find it advantageous to make
a larger-plate earth electrode. The earth electrode is usually best placed close to, but on the body
side, of the other electrodes. ;

You may find that your position in the room is quite critical in terms of mains interference. lf you
have a vast quantity of interference, it is almost certainly due to high resistance electrodes: refix the
electrodes or — for real problems — rub the skin well with jelly and hold the electrodes down with
rubber bands. Make sure the skin is clean and dry between the electrodes.

Stimulation: use two electrodes only, no earth, and fix them about an inch apart on a small block
of wood by drilling holes for thelr shanks. Carve a gap between the electrodes in the wood so as to
prevent electrode jelly creating a short circuit between the electrodes. TAKE GREAT CARE TO
HOLD ONLY ON TO INSULATED PARTS OF THE ELECTRODE PAIR — so that current does
now flow from arm to arm across your heart: electrical stimulation of the heart can be FATAL.

The negative, depolarising, electrode Is active in nerve stimulation. To locate a main nerve trunk
either to directly activate a muscle group or to give a painful stimulus, you will need to probe
around the inner side of the lower arm with the active electrode. Keep the electrodes moist with
jelly but your skin clean and dry — otherwise the current will simply short across the surface.

Hairy skin Is a good location for pain stimull. You will need to hold the electrode pair onto the
arm during threshold testing with rubber bands. Beware of obstructing the blood flow.

PRACTICAL COMPUTING January 1980

Figure 1: Outline of the sensory-motor pathway:

learned form

learned
consequences

sensor

PROM

coding

sensor code

sensory analysis

form code

intrinsic form

object code

intrinsic consequences

motor skills

intention code

motor function

motor code

Circles représent computing regions of the brain and spinal cord whilst the boxes show the type and relative quantity of memory employed in the computing
process. ROM (real-only memory) corresponds to the genetically formed memory and PROM (programmable read-only memory) the memory formed by
experience and skill. PROM is laid-down In chemical form subsequent to short-term (electrical) memory (RAM).

How long do you think for?

Having got used to the idea that your com-
puter can be used to intertogate you, rather
than vice versa, let’s test how long it takes
different parts of your brain to work. This
requires no extra machinery, except you, and
some well designed timing routines and tests.
Figure 1 shows the general passage through
the brain of a stimulus and its consequent
response.

You will see how although the technique of
signalling (electrical pulses and chemical
release — the brain’s equivalent to ASCII
coding) may remain constant, the content
changes from, a low-level language to a high-
level one and back again to low-level, a process
analogous to swopping between machine
code and full-blown FORTRAN. At the
highest level both your ROM and PROM
memory will be hard at work reminding you of
all sorts of problems and thus generating an
inhibition of the output. The signal must thus
search through longer and longer pathways
before coming to an answer.

Physiologists reckon that it takes | to 2 msec
to propagate froim one cell to the next and that
the divergence (the fan-out capability) is about
50. Thus theoretically it need take only five
steps for a message from one cell to reach out
to 108 brain cells. Allowing the same again for
reconvergence we see that your longest central
delay time need only be 20 msec. How long do
you take?

PRACTICAL COMPUTING January 1980

FOR JO TO 2000+3000*RND(1)

: SYS(826)
"TRY AGAIN'

PRINT 'clr.
IF T=0 THEN

screen'
PRINT

'DEPRESS ANY KEY WHEN THIS DISPLAY DISAPPEARS'

: NEXT

: T=PEEK(1000)+256*PEEK( 1001) !
: GOTO 100

PRINT 'YOU TOOK'T/20' MILLISECONDS'

DIM T(20)
N=O :cg = W "
PRINT "clr. PRESS:
C=INT (2*RND(1))
PRINT C$ ;: IF C=1
SYS(826) : GET A:
256*PEEK( 1000)
GOTO 110

1=LONG LINE 0O=SHORT LINE"
: FOR J20 TO 2000+3000*RND(1)
THEN PRINT C# ;
IF A =C THEN N=N+1
: IF N=20 THEN200

: NEXT

: T(N)=PEEK(1000)+

Figure 2 (See also program page 109)

Box 4 shows a machine timer code routine
(BASIC routines are too slow) which checks to
see if a key has been pressed. It repeats every
50} s and counts to 65535 (64k) thus giving a
time-out of about 3.3sec. The routine returns
to BASIC either after the keystroke or at time-
out. The count is in stores 1000 and 1001 and
contains zero at time-out. Thus a typical
BASIC dialogue would be as shown above in
Figure 2.

When estimating reaction times it is

important to make several, say 20, tests in

a row, preferably interspersing the test

measurement with a control measurement. The
measured times (‘latencies’) of correct
responses should be stored in an array for later
analysis — don’t display them immediately
unless you are really ready to study the effects
of biofeedback.

The most obvious analysis is to calculate the
mean of the array, but this can suffer badly if
you sometimes get tired with the experiment
and give very late — but correct — responses.
You need the first modal value (ie the most
common value, the first peak on an interval
histogram) but for small simple sizes this needs

rather clever programming to average the
histogram.

An effective method — but much hated by
statisticians — is to exclude values that are a
long way from the mean and then recalculate
the mean. The problem is to decide on a
criterion for excluding values: either you can
exclude those that are further than two
standard deviations from the mean (SD =
SQR((S2-S1*S1/N)/(N-1)) where S1 and S2 are
the sums of the values and of value squared for
the N measurements) or, more simply —
exclude those that are more than twice or less
than half the mean.

To test how long various thinking processes
take, you must have a baseline of how long the
sensory and motor processes take. One could
use the simple ‘blank screen’ test programmed
above, but to make a closer match to the test
protocol, the decision you have to make is
whether the line presented is a short line (five
white field blanks) or a long line (ten white
blanks): the reaction time is stored, of course,
only if you get the question right.

To test your arithmetric speed you need
change only line 110 so that 1 = RIGHT: 0 =
WRONG’? and line 130 to have, for example,

PRINT " 3 + 11 = "141 (12C)*
(INT( 4*RND(1))+1)

The variable C codes for whether the display
is correct or not; here if C = 0, an error in the
addition sum is forced. Simple variations will
allow you to check your calculating speed for

So you thought anaesthetics were painless?

650X/PET 2001

186 DATAI69. i REM LDA# 1
105 DATA141.232.3 <:REM STA 1608
11@ DATAI69.8 “REM LDA# @
115 DATAI41,233.3 <:REM STA 1001
126 DATAI69. 1a

125 DATAI73 "REM TAX
138 DATAZH2 >REM DEX
13S DATA288, 253 ‘REM BNE

14@ DATAI73, 13.2

145 DATA2Z@S, 1G 7REM BNE +14
15@ DATAZ38.232,3 <:REM INC 1960
155 DATA288,3 7REM BHE +3
16@ DATAZ38.233.3 <:REM INC iH@1
165 DATA2@8,235 REM BNE -21
176 DATAS6 “REM RTS

175 DATASS9

268 L=826

315 GETAS

various types of arithmetric; you can compare
this with BASIC if you want to be depressed.

Sexual differences

An alternative sort of test is of your power of
English vocabulary. Line 110 will ask you to
decide,if the ‘word’ presented is or is not a real
English word, whilst line 130 will use C to

Box 4: Machine code timer for

‘REM LDA# 16 **DELAY

-3
?REM LDA 525 *#KEBD CHAR

216 READX: IFXC2S56THENPOKEL. X:L=L+1 :GOTOZ1&
304 PRINT"M@ PUSH KEY WHEN SCREEN CLEARS"
31@ FORJ=1T02800+32G0#RND¢ 1 > NEXT: PRINT "TI" > GETAS :SY'S¢ 826)

PRINT"YOU TOOK" (PEEK(100G>+256#PEEK¢1@01>9/20" MSEC TO PUSH "As: GOTO306

select from an array of real words or from an
array of dummy words like MURNT. This time
you should be quite impressed with your skills
considering how long it would take either you
or a computer to look up the words in the
dictionary. Don’t cheat by both inventing the
dummy words and testing your timing. Set up
another bit of program so that someone else
can enter words into the arrays.

These two tests are clearly of different types
of activity, the arithmetric, of exact logical
solutions, whilst the word test is more akin to
pattern matching. Psychologists have claimed
to find a consistent sexual difference in these
skills, the male being analytical and the female
— as you might guess — verbal. Of course such
a difference may well occur on average because
of the different skills the sexes are expected to
acquire, both in and out of school, but the
psychologists invoke both physiological and
anatomical evidence to suggest that the
difference is innate.

The physiological evidence depends on the
differing contributions of the left and right
sides of the brain for differing activities, since
this can be measured to some extent by
measuring the overall activity of each side —
the electroencephalogram, EEG or ‘brain
waves’.

We shall return to this issue later in the series
when the measurement and analysis of brain
waves is considered. Suffice to say that the
news for the male is glum, except where the
desire to dominate his environment becomes
relevant. Perhaps you can try to devise tests to
maximise this effect? For example, comparing
different types of ‘loaded’ words such as ‘iron’
and ‘milk’. Plan carefully and you can publish
your results.

WARNING: The system des-
cribed here by Chris Smith
seems to be safe. But readers
are warned not to modify the
circuit in any way, and to ob-
serve strictly the author’s
cautions on not letting the
current pass from one arm to
the other across the heart.
Practical Computing can take
no responsibility for injury or
death caused by its use.

PRACTICAL COMPUTING January 1980

Keen Computers have. 46
an “Appie baye nearer to.you! —™

Apple ll 16K 750.00
Additional 16K RAM 69.00
Applesoft ROM 110.00
RS232 Card 110.00
SuperColour 90.00
Disk Drive and Controller 398.00
Disk Drive w/o Controller 355.00
Corvus LIMB Disk 3500.00.
Speechlab 127.00
Apple Clock 140.00
Supertalker 190.00
Printers from 450.00

Software packages are available for most
business applications.

A few are:

Word Processor, Addressing+ Mailing,
General Ledger, Sales Ledger, Purchase
Ledger, Incomplete Records Accounting,
Stock Control, Payroll, Estate Agents.

All prices are subject to change
without notice.

Apple Bases

Nottingham Stoke-on-Trent
Keen Computers Ltd. Tekdata Ltd.
Tel: 0602 583254 Tel: 0782 813631

Derby Tamworth
PTS. (Electronics) Ltd. Abel Computer Systems
Tel: Derby 43592 Tel: 0827 895309

London: Birmingham
Adda Computers Ltd. C.PS. Data Systems Ltd.
Tel: 01-579 5845 Tel: 021 707 3866

- Sumlock Bondain Ltd. Northampton
Tel: 01-250 0505. Ford & Wright Ltd.

: Tel: 0604 39660
Leicester

Arden Data Processing Ltd. Sheffield
Tel: 0533 22255 Datron Interform Ltd.

Scunthorpe. Tel: 0742 585490
Computer Facilities Ltd. Newcastle-upon-Tyne
Tel: 0724 63167 PI.PS. Computer Services
Ediniuigh Tel: 0632 482359
Microcentre Ltd. Canterbury
Tel: 031 225 2022 M.D. Wright Data
‘ a) | Kenering Services Ltd.
Pi a) H.B. Computers Ltd. Tel: 0227 69090
@keen computer itd ¢ aig rey
‘ BarrowuniFurness Newbear Computing Stores

5b the poultry / coeneeaiComnpilten Tel: 0635 30505
Nottingham Services Ltd.
Tel: 0602 583254 Tel: 0229 24621 ye)

Telex: 37297 (keenco) @ Circle No.

Applell plus

Apple II Plus will change the way you
think about computers. That's because it is
specifically designed to handle the day to
day activities of education, business,
financial planning, scientific calculation
and entertainment

~ APPLESOFT
A fast, extended 10K BASIC with 9-digit
precision and graphics extensions
* HIGH RESOLUTION GRAPHICS
Ona matrix of 280 x 192 individually
addressable points
* AUTO-START ROM
With power on boot of applications
programs, reset protection and improved
screen editing

INTERNAL ‘MEMORY EXPANSION TO
64K BYTES
For big system performance at a low cost
* EIGHT EXPANSION SLOTS
To let the system grow with your needs

Nett VAT Total
Apple II Plus,
16K RAM - 750,00 121.50 871.50

APPLE PASCAL
Apple Pascal is the new extension to
microcomputer power

Pascal Incorporating UCSD PASCAL TM,
offers extended features in a complete
interactive package employing todays
most sophisticated structured
programming language. It provides
advanced capabilities that boost
performance and cut development time for
large business, scientific and educational
programs

This software package provides the most
powerful set of tools yet available for the
microcomputer programmer

FLOPPY DISCS

Gives your system immediate access to
large quantities of data. The subsystem
consists of an intelligent interface card, a
powerful Disk Operating System and one
or two mini-floppy drives

Nett V.A.T. Total
398.00 59.70 457.70

Floppy disk
Subsystem. .

Second disk drive
and eonnectitg
eable...... . 355.00 53.25:408.25

Parallel Printer Interface Card

Allows you to connect almost any popular
printer to your apple, A BASIC program
can produce-hard-copy output as easily as
it prints to the TV monitor screen.
Command interpretation and printer
control details are handled by the
firmware built into the card, to eliminate
user programming requirements

Nett VAT Total
110.00 16.50 126.50

Parallel Printer
Interface Card

Communications Interface Card

Allows your Apple to “talk” (through a
modem) with other computers and
terminals over ordinary telephone and
load programs over the phone, send
messages to remote terminals or access
your office computer from the comfort of
your home.

Nett V.A.T. Total
. 110.00 16.50 126.50

Communications
Interface Card ...

High Speed Serial Interface Card

Allows Apple to exchange data with
printers, plotters and computers in serial
format at up to 19 2K Baud

Nett V.AT. Total
High Speed Serial

Interface Card-...... 110.00 16.50126:50

Ippic computer

Nascom 2

Microprocessor

Z80A 8 bit CPU. This will run at 4 MHz
but is selectable between 1/2/4/ MHz.
Hardware

12° x 8" Card

All bus lines are to the Nasbus
specifications

All bus lines are full buffered

Memory

On-board, addressable memory:

2K Monitor — Nas-sys 1

1K Video RAM (MK4118)

1K Work space/User RAM (MK4118)
8K Microsoft Basic

{MK3600 ROM)

8K Static RAM/2708 EPROM

Keyboard

New expanded 57 Key Licon solid state
keyboard especially built for Nascom
Uses standard Nascom, monitor
controlled, decoding

The T.V. Peak to peak video signal can
drive a monitor directly and is also fed to
the on-board modulator to drive the
domestic T.V

On-board UART (Int. 6402) -which
provides serial handling for the on-board
cassette interface or the RS 232/20mA
teletype interface. The cassette interface is
Kansas City standard at either 1200 or
300 baud. This is a link operation on the
Nascom-2

PIO
here is also a totally uncommitted PIO
K3881) giving 16, programmable, 1/O

lines

Character Generator

The 1K video RAM drives a 2K ROM *
character generator providing the
standard ASCII Character set with some
additions, 128 characters in all, There is a
second 2K ROM socket for an on-board
graphics package which is software
selectable

Nett V.AT Total
Nascom-2 in kit

POT j ous 2ss 295.00 41.25 339.25
Power Supply 24.50 3.68 2818
GraphicsROM,.. 15.00 2:25 17.25

REED RELAY BOARD

Put your Nascom to work with the new
Microdigital Relay Board

16 Reed Relays, totally isolated 200 mA,
50 V.D.C. 5W max each. Operate and
release time 1-ms (including bounce).

Single sided, glass fibre board, with gold
plated edge connectors and silk screened
component layout

Plugs directly into Nasbus, does not
interfere with normal Nascom operation.
all interupt and D.M.A. Daisy Chain Links
carried on. Draws only 250 mA from each
of the + and + 12V Rails

All components supplied, all IC's
socketed, easy to build, and easy to
program in Basic or Machine Code.

* Occupies 2 consecutive ports, link
selectable — several boards can be used
on one Nascom system.

Output ts via front edge connector on
0.1" centres. Uses standard edge
connectors for connection to controlled
devices

Complete manual with sample software.

Applications

Light displays
* Industrial process control
* Model Railway Control
* Pre programmed music generation
* Robots, Central Heating Systems
* Stepping Motors

Nett V.A.T. Total
15.00 225 17.25
49.95 7.4957.44

Assembled -

-. 60.00 9.00 69.00

MICRODIGITAL1980

Rockwell
Aim 65

Thermal Printer
* Wide 20 column printout.
* Versatile 5 x 7 dot matrix format
* Complete 64 — character ASCII
alphanumeric format
Fast 120 lines per minute
* Quiet thermal operation
~ Full Size Alphanumeric Keyboard
* Standard 54 key, terminal-style layout
* 26 alphabetic characters
* 10 number characters
* 22 special characters
9 control functions
3 User-defined functions

True Alphanumeric Display

* 20 characters wide

* 16-segment characters

* High contrast monolithic characters
- Complete 64 — character ASCII
alphanumeric format

” Read/Write Memory, using R2114 Static
RAM devices. Avallable in 1K byte and 4K
byte version
* 8K Monitor Program Memory, using
R2332 Static ROM devices. Has sockets to
accept additional 2332 ROM or 2532
PROM devices, to expand on-board
Program memory up to 20K bytes
* R6532 RAM Input/Output-Timer (RIOT)
combination device. Multipurpose circuit
for AIM 65 Monitor functions

Two R6522 Versatile interface Adaptor
{VIA) devices, which support AIM65 and
user functions

Nett VAT Total

AIM.65 with 1K 24950 37.43 286.93

AIM-65 with 4K 315.00 47.25 362,25

8K BASIC ROM 70.00 10,50 80.50
4K ASSEMBLER

ROM 5 59.50 8.93 68.43
CASE Wacludes

PSU) 78.00 11.70 89.70

P.S.U 41.83 6.27 48.10
MOTHERBOARD 136.50 2048 156.98

Texas

The remarkable TI-99/4 Home Computer
Superior colour, music, sound and
graphics — and a powerful extended
BASIC all built in. Pius a unique, new
Solid State Speech Synthesizer and T.I.'s
special Solid State Software

The T.1.99/4 was designed to be the first
true home computer — skilled computer
users and beginners alike will be able to
put it to-effective use right away. You can
begin using the Tl Home Computer
minutes alter unpacking it; simply snap in
a Solid State Software Module, touch a-few
keys and step-by-step instructions appear
on the screen

Powerful TI-Basic: Accuracy and power
for demanding technical applications, yet
easy to use for the beginner. 13-digit,
floating point Basic, with special features
and extensions for colour, sound and
graphics.

* 16-colour graphics capability — Easy to
use, high resolution graphics with special
features that-let you define your own
characters,.create animated displays,
charts, graphics and more, with a
resolution of 256 x 192 individually
addressable points.

*, Music and sound effects: provides
outstanding audio capability. Build three-
note chords and adjust frequency,
duration and volume-quickly and simply.

Console:
CPU: 9900 family, 16 bit microprocessor,
plus: 256 byte scratchpad RAM.

Memary:
Total combined memory ca SEG ets Bytes
Internal ROM.......... ... 26K Bytes

sharp.

SHARP M2Z-80K

* Z-80 based CPU.

* 4K Byte monitor in ROM.

* Internal memory capacity from 4 to’ 48K
RAM.

* 14K Extended BASIC

* 10 in video display, 40 chars. of 24

lines

* 80 x 50 bit mapped graphics

* Extensive character set with upper, lower
case, graphies etc

* Full 79 Key Keyboard

* Built-in musie synthesizer with 3 octaves.
* Fast reliable cassette unit with tape
counter 1200 b.p.s

* Wide variety of system software on
cassette

* 50 pin bus connector for system
expansion

A complete personal computer system for
the micrécomputer user, at an economic
pzice. The Sharp comes complete with all
necessary peripherals, sample software
and excellent documentation — giving the
user a personal system of unmatched
flexibility and ease of use. At the heart of
the machine is the Z-80 CPU — widely
accepted as the most powerful 8-bit CPU
on the market. A 4K byte system monitor
controls system operation. From 4 to 48K
of RAM can be resident on board; enough
room for the most demanding
applications

An extensive graphics character set plus 3
octave sound generator fast cassette unit
hi-resolution video monitor complement
these basic facilities. It has the ease of use
and compactness of the “black box”
computer combined with the extensive
peripherals and facilities for expansion

Sharp Basic occupies 14K of RAM; and
offers extended features above those of the
normal! microcomputer implementations;

Model Nett VAT. Total
6K. < 520.00 78.00 598.00
10K - : .. 540.00 81.00 621.00
18K nora 620.00 93.00 713.00
22K 5 640.00 96.00 736.00
34K ........ 740,00 111.00 851.00

Internal RAM... ..... 16K Bytes
External ROM (Plug i in software
modules) . .... 30K Bytes

Keyboard
Staggered QWERTY Layout, full travel with
overlay for second functions.

Sound
5 Octaves, 3 simultaneous tones-plus noise
generator

Colours: 16
Graphics resolution: 256°192

Input/Output:

Composite video and audio output for
monitor. Interface for 2 audio cassette
recorders 44-pin peripheral. connector
with system memory and address signals
available. Mini-earphone jack. Hand
controller interface

Built in software:
14K Byte T.I. BASIC, equation calculator
and control software

Size: 25.9°38.1°7.1¢cm

Display: :

Uses colour monitor, 24 slines of 32
characters.

Net! V.A.T. Total

Console ... 569.57 85.43 655.00
Modules . Baath 15 - 40.00"
Joysticks. a ha 25/00:
Speech synthesizer. an 45.00"

‘Please note these are estimated prices only.

Commodore

A complete Computer for the price of a
good typewriter! With a library of over 200
programs in business, science, education
and entertainment.

Pet can store and retrieve data which
conventially occupies large storage
capacity, and solve numerical problems
traditionally tedious and time consuming

Ease of Operation

The Commodore PET comes complete with
a built-in TV. screen, and keyboard as-
well as its full computer circuitry. It is
plugged into any 13 amp and no special
computer knowledge is needed for
running standard programs, Personal
programs can readily be written in the .
BASIC computer language of PET which is
easily learned

An Expandable System

Further expansion is a prime design
concept enabling PET to be made the heart
of a much larger system incorporating
printers, floppy discs etc.. as and when
required

Computers
PET 2001-8 — PET with integralcassette and
calculator type keyboard.6K bytes memory
Nett WAT. Total
550.00 82.50 632.50

PET 2001-16N — PET with 16K bytes

memory and large keyboard. External
cassette optional.

Nett V.A.T. Total

675.00 101.25 776.25

PET 2001-32N ~— PET with 32K bytes
memory and large keyboard. External
cassette optional.

Nett Vv

ALT. Total
795.00 119.25

914.25

Computhink Disk Units
400K Random

for 8K Pet.......
400K Random for
New Pet2.......
800K Random for
New Pet2.......

795.00 119.25 914.25
840.00 126.00 966.00
995.00 149.25 1,144.25

Phone in your
Access/ Barclaycard

0112360707

Please Send Me:

Acorn

This compact stand-alone micro-computer
is based on Eurocard modules, and
employs the highly popular 6502 MPU
Take a look at the tull specifications, and
see how Acorn meets your requirements.

The Acorn consists of two single
Eurocards:

1. MPU card; 6502 microprocessor, 512 x
8 ACORN Monitor; 1K x 8 RAM; 15-way
I/O with 128 bytes of RAM; 1 MHz
crystal; SV reg, sockets for 2K EPROM
and second RAM I/O chip.

2. Keyboard card; 25 click-keys (16 hex, 9
control); 8 digit, 7 segment display. CUTS
standard crystal controlled tape interface
circuitry

Acorn Operating Manual
With Acorn, you'll receive an operating
manual that covers computing in full, from
first principles of binary arithmetic, to
efficient hex programming with the 6502
instruction set. The manual also Includes a
listing of the monitor programs and the
instruction set, and other useful
tabulations; plus sample programs
Nett V.A.T Total

-.. 65.00 9.75 74.75

75.00 11.25 86.25

Rito
Ready Built.
Acorn Memory
A high quality fibre glass.through hole
plated,PCB with solder resist and
component Identification, this eurocard
has provision for 8K of RAM (2114) and
8K of EPROM (2732),

: Nett

95.00

V.A.T. Total:

8K RAM (Kit) 14.25 109.25

ACORN V.D.U

The Acorn V.D.U. Board connects to the
Acorn Computer Bus and contains
memory mapped character storage RAM
which is transparently written to or read
from, by the C.P.U

An MC 6845 programmable controller .C.
Provides all the synchronisation signals to
drive a 625 line SO fields per second
V.D.U. together with read addresses for the
character R.A.M. Characters are then fed
to an SAA 5050 character generator IC
which produces the necessary dot patterns
to create the characters to refresh the
V.D.U.

The SAA 5050 produces Teletext standard
characters and has Red; Green and Blue
drive outputs giving coloured characters
or graphics.

25 Brunswick Street, Liverpool L2 OPJ
Tel: OS1-236 0707 (24 Hour Mail Order)
051-227 2535/6/7/8 (All other Depts.)

1 Enclose:
Cheque/Postal Order No.

Name

Access No.

Address

Post Code

“Official orders over £10 are welcome, with normal 30 days credit extended Jo

bona-fide Commercial Organisations.

Terms are implemented at the discretlon of the management.

| Barclaycard No. — SSS

Bigger and better than ever!

@ Circle No. 178

| ee

IMAICRODIGITA

25 Brunswick Street, Liverpool L2 OP]
Tel: 051-236 0707 (24 Hour Mail Order)
051-227 2535/6/7/8 (All other Depts.)

Microdigital Software Announce

5 packages which are

Mail orders to: MICRODIGITAL LIMITED,
FREEPOST (No Stamp Required)
Liverpool] L2 2AB.

General Ledger . £295.00
Purchase Ledger £295.00
Sales Ledger. £295.00
Stock Control £200.00
Payroll , £360.00

These packages are now available, demonstrations on request.
Ring 051-227 2535 and ask for Graham Jones (Software Manager).

These are fully tested systems which run on the Apple/ITT 2020 with one or two disc
drives

The Stock Contro] package can handle up to 1250 stock Items and uses two diac

The Mighty Microdigital

Microdia tte! are one of the largest and longest established Microcomputer firms In
urope

We sell a wide range of systems, backed up by support services that are second to
none,

Our present retail outlet is at 25 Brunswick Street, Liverpool, Our well informed staff
are happy to demonstrate equipment, provide technical help, or just chat.
Microdigital (mail order) is the fastest, friendliest and most efficient mail order service
available. All orders (or an acknowledgement if the goods are temporarily out of ©
stock) are despatched by return post. Telephone orders are welcome (24 hours a day)
and we even have a ‘'Freepost” service so you don't have to remember the stamp!
Microdigital Manufacturing is our hardware department. We carry out repairs and
servicing in-house rather than depending on the manulacturer. In addition we design
and manufacture our own peripheral boards for the systems we support. Custom
design services are also available

Microdigital (Software) is responsible for the
development of commercial, high quality, compute
programs. We can advise on the suitability of an
existing package, modify the package, or write a
completely new system to the customers
specification.

Microditial (Hire) provides a service for potential
customers — the capabilitities of a particular
machine can be evaluated without a substantial
capital investment.

All in all we try and provide the most competent
service in the Microcomputer industry

The Microcomputer shop providing a
complete servicefromasinglechiptoadata
processing installation.

MICRop;
QUIGITAL

Friendly, expert staff always on hand - ey i
Our new, glossy, 16 page brochure isnow

thetalk of the industry! — Send for your free
copy today

At last! Britain's very own monthly
journal for Microsoftware...

First issue includes:

SARGON meets the Nascom-1 — J. Haigh.
Programming practices and techniques — Dr. M. Beer.
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We brought the first five Apples into the U.K. in November
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She SAT Pa a

Upsetting the Applecart

Dave Hebditch talks to Andre Souson, the President of
Eurapple and gets some tantalising glimpses of unripe fruit.

DH AS YOU MUST BE AWARE, Eur-
apple has been in the news recently
concerning changes in your general
marketing approach. For the benefit
of the readers ofPractical Com-
puting, 1 wonder if you could explain
exactly what Eurapple is, and the
nature of your marketing policy with
respect to Europe?

AS Certainly. Eurapple is a separate legal
entity from Apple Computer Inc. We
operate as the international division
of Apple and we are responsible for
the marketing (and the engineering,
if needed) of the units to be exported
everywhere in the world with the
exception of Japan and Canada.
We will soon set up our own sub-
sidiary in Japan.

You mentioned that there has been a
change in my general marketing
policy in the UK: we changed our
distributor. We are a young com-
pany, just two years old. We took the
risk and the challenge to start mar-
keting world-wide at the same time
that we started marketing in the
United States (which was July 1977).

I made this recommendation to Apple
at the time because I strongly
believed that we had to establish
a base for the competition which
was going to come and which already
had distribution outlets (although
these outlets were not for computers
but, in the case of Commodore,
calculators and for Radio Shack,
electronic hardware).

At about the same tise, we were ap-
proached by ITT Consumer Elec-
tronics in Europe who asked if we
would enter into a manufacturing
licence agreement with them. So we
entered into a non-exclusive agree-
ment with ITT by which they have
the right to manufacture the Apple
II and sell them in Europe only.

Now, we happen to be a very ambitious
company. And we have to work very
hard to justify these ambitions.

DH How do you see the world-wide
market for the home computer?

AS Talking personally, I have yet to
see any kind of evidence that there
exists a market for the so-called
‘home computer’.

DH So how would you define a home
computer?

AS I have not yet found a definition for
it, and I can tell you that we have
people in this company searching
desperately for a definition and one

PRACTICAL COMPUTING January 1980

day we are going to find our own
definition.

But that day is not here yet and certainly
we will not come with any definition
of this market before we see how
people who have cautiously entered
the home computer business, namely
Mattel, Texas Instruments and Atari,
are going to fare.

DH Are you really talking about pricing

policy here? Are you suggesting that
in order to compete in the home
market place, it will be necessary
for Apple to enter into a fairly severe
price-cutting exercise in order to stay
with Atari and the others?

AS No, I don’t because the price of the

Atari and the others is not drastically
different from the price of the Radio
Shack or Commodore or even the
low-end Apple. But it seems to be
a question of performance; it seems
to be a question of hardware/firm-
ware/software choices — do you
go ROM or don’t you? Do you go
tape cassette or do you go disk?
What are you going to do with it?
Do people want it?

So for the home computer right now,
there are question marks and I
believe that the industry as a whole
is going to try and respond to these
question marks. We are watching
the companies who have already
entered the field very closely and
at the same time continuing to have
a group of engineers working on
what they think (we give them free
range), is going to be the home com-
puter of the future.

But what we are now at Apple is a

‘personal computer’ company and by
‘personal’ J mean that we are making
computers that will be used by in-
dividuals not by a group of persons.
Ideally, the business computer that
Apple is going to make will be desk-
top stations, single-station com-
puters, even if they are linked by a
net. And all other segments of the
industry, that is education, scien-
tific and industrial, hobby and per-
sonal entertainment will be the same
thing.

More performance, lower
cost

We think that the market in this field
is enormous. I think that the phen-
omenon of personal computers is
due to the fact that you can, through

André Souson

technological advance, manufacture
more performance in computers
at significantly less cost, than was
possible 10 years ago.

Speaking as an individual, not as a

company man, I question myself
and say, why does Apple exist? I
think it is a legitimate question when
you see that there are companies
like IBM, DEC, Data General,
Hewlett Packard and many others.
I think that the reason that Apple
exists and survives is that these com-
panies could not afford overnight to
cut prices so that the new line of
products would compete with the
Apple, without jeopardising their
previous line of products.

DH As you suggested earlier, Apple is

fairly price competitive in the Us
with Commodore, Tandy and the
rest.

They are less expensive if you take
the system complete. If you take the
32K Apple-plus and a disk, there
is no question that we are less
expensive.

DH Unfortunately, that is not true in

the UK and Europe generally. If
one makes a comparison between the
Apple and the PET (and this might.
be a little unfair because Commodore
actually assemble the PET in the
UK)...

. . . they have closed and sold their
plant in the UK in Eaglescliffe . . .

DH That’s not true. My understanding

is that they have relocated it to
Slough and I have actually been
there and seen them assembling
PETs in their factory.

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PRACTICAL COMPUTING January 1380

AS Until very recently, the starting price

for an Apple in the UK has been
about £850, depending upon what
the dealer wants to offer, and to
this has to be added a monitor or
colour TV of some kind which can
then take the price up to over £1000.
The equivalent Commodore price is
about £600, which is a quite signifi-
cant difference.

AS For which PET?
DH The standard 16K model.

As an Apple user myself, I share the
concern of many Practical Com-
puting readers that there seems to
be a very major mark-up in the price
and it is my understanding that in
the past Apple have been providing
to the European market systems
as a price which is equivalent to the
U.S. end-user price.

Not unexpectedly perhaps, this has

created a certain amount of concern.

As the European market-place

develops, do you see that there is

any way in which this price can be
reduced somewhat, so that it is more
on a par with the US price?

David, there are a number of as-

sertions in what you have just said

that I would like to answer. Firstly,

I would like to clarify what you

said about Apple Inc, supplying

systems to Europe at the same price
as the U.S. Can you clarify this?

System cost to end-user

DH The price to the distributor in

Europe has been approximately

equivalent to the US end-user price.

Absolutely not. The price to a dis-

tributor in Europe is less than the

dealer price in the United States.

Let me comment on this. I know

that a person like you who is fam-

iliar with international mrketing
will understand.

Two years ago when we started, we were
a new company with an unknown
product. A company in this situation
does not arrive in Europe to meet
experienced distributors and say
‘here is my marketing policy’ be-
cause he does not know what he
should be asking for in his product.

Therefore, it took us a while to learn
about our distributors and how to
work with them and to understand
our dealers and the market place.
How we understand what the dis-
tributor and dealers need as a
margin to operate. Now we under-
stand what kind of support they
both need and also what the cus-
tomer needs.

Forexample, wehave(about four months
ago) begun to implement both in
the United States and overseas, very
clear marketing policies and pro-
cedures. We are implementing a
service policy which guarantees the

PRACTICAL COMPUTING January 1980

end-use a 24-hour turnaround time
anywhere in the world.

“Unlimited” two-year
guarantee

We are so confident in this policy that
soon we will introduce a two-year
extended warranty on the Apple
which will provide the end user with
with unlimited labour and parts for
two years for a very modest amount,
something like $200 to $300. This
is the result of expensive work which
has been done by a remarkable man,
Mr. Will Houde who was hired by
us back in February and who came
from Hewlett Packard and is our
new world-wide service manager.

Now, we have several hundred dealers
to train in the United States and
we have the same amount to train
in Europe, so it will take some time
to implement this policy. But it is
there. In the UK. Microsense has
begun to implement this plan.

On this question of pricing, we are not
selling the same Apple in countries
which have either PAL or SECAM
or 220 Volts. Here I am showing
you a PAL TV set and I want you
to be the first person to see the brand
new PAL colour card.

DH This is a lot smaller than the original

one.

My first card made in July 77 was

brute force. I took the MGSC de-

modulated and remodulated it in

PAL. This one uses custom inte-

grated circuits and there you see

some high resolution graphics using
it.

DH That is far superior in quality to the
present card.

AS That is even better. quality than the
NGSC.

DH Will this be available as an up-grade
to existing users?

AS That is right. It will be available by
the end of October. There is no
way anybody can make better than
that.

DH I can certainly commend that to
the readers.

AS We do not make the same Apple
therefore. The Apple that we make
for Europe, instead of having the
525 lines, has 625 lines of TV scan.

People tell me it is easy to do on our
boards, but it is not true. We do
this and that with a few wires on the
board but in addition we change
the crystal. The crystal must hve
an extremely accurate frequency.
We have to make one or two circuit
variations; instead of using the
standard TTL we use Schottky TTL
for the speed.

So there are differences. On 90% of
all the TV sets and 90% of all the
conditions, just a crystal change

and the wires on the board will do
the trick. Sometimes 10% will need
the extra things doing. It costs us
in manufacturing costs something
like $60. And plus the cost of the 220
volt power supply which is signifi-
cantly more (something like 50% to
60% more than a U.S. power
supply).

DH But even if that and the video card

were together double the U.S. price,
that is a very small contribution
in what is a fairly major price differ-
ence, and we are talking about almost
double the price in Europe.

Let me further comment on that.
The video card is an add-on, so let’s
not even talk about the cost of this.
Today the cost of the Apple is £750
for 16K. This translates exactly after
Custom Duties (but without VAT) to
something like $1600. Take about
16% import duties out of that and
you get $1309. It cost me about $80
more in manufacturing costs. At
retail prices we are going to end up
with 2 difference of something like
$159 to $200. So take the Apple’s
US price of $1200, add $180 and
you get $1380. You will not find
a price difference of more than 25/
30% between US and European
dealers.

It costs a lot of money to market overseas.
DH One way of getting around import

duties and shipping costs would be
to manufacture within the EEC.
Are there any prospects of that?

I think this is true in principle but
I do not think it is true in reality.
To give you an example, only 25%
of the components used in the Apple
are readily available in the EEC.
Some of them are not even available
in the US — we have to import
them from Japan.

DH A large proportion of the manufac-

turing costs must be the assembly
costs, especially the labour.

The labour is very little in Apple.
We have optimised this process to
such a point that the labour is not
really an important factor. We do
have prospects to diversify our
source of manufacturing because
we believe that the quality will be
very important’ and our interests
would be in several locations, and
certainly the EEC is under consider-
ation, but the reason is not going to
be cost-cutting.

As a matter of fact, I believe that our

costs will increase if we manufacture
in several places because of the hassle
of communication and the transfer of
know-how and so forth.

DH What sort of time-scale are you

talking about, or is it too early to
decide?

I think that we will have firmed up
plans before the end of 1980.

DH The other consideration that comes

to mind is the general developments
within the corporation over the next
period. You did speak earlier on
about the question of what is a
home computer and it is fairly
obvious that a lot of people who
went into the business specifically to
make a computer for people to use
at home (if I can make my own
definition), have subsequently found
that the vast proportion of their
market place is with small businesses.
What sort of proportion do you
have roughly between the home
market and the business environ-
ment?

But it will cost you something like
£200/£300? To add 32K memory to
a 16K Apple today costs you £138.
And you can go to 48K and 64K
with the lanugage card if you want
to.

DH | think your PET prices might be a
little high but I accept your point
about expansion capability. When
you said you were going to concen-
trate on the business market place
in terms of product development,
are you able at this time to give any
ideas of what that is going to mean
in practical terms? What sort of
products are you thinking of?

future. So that is what I can tell you;
we are evolving towards the high end
of the market.

At the same time, as I mentioned at the

beginning, we are not ignoring the
very low end. If there is such a
market for the so-called home com-
puter (which makes sense for us
— meaning that it will not be a high
end video game or a toy) then we
wil] be in it with what we think will
be the best product.

DH But the priority in the short term

is going to be in the personal com-
puter for the professional market?
Yes, because we do not yet see any

AS North America or Europe?
DH Both.
AS They are very different. In the

evidence of the ‘home’ market.
DH If and when the home market
develops, will you respond to that

New Apple

United States the hobby market
today (although the percentage is
increasing) is approximately 35%;
in Europe it is 5%. In the US we
are penetrating more and more
strongly the business market because
that is the way we are going to
develop.

Professional users

Or perhaps I should say the professional
market — let’s not make a difference
between an accounts office and the
needs of a lawyer’s office. In Europe
I dare say that 70% of everything I
sell finds its way into professional
usage. The rest is made up of edu-
cational and other sales.

DH | hate to bring the price question up
again, but do you think that is a
reflection on the differences in
disposable income between Europe
and America? Is it a system that
can be afforded really only by
small businessmen in Europe on a
large scale.
Curiously enough, I must say that
I am amazed to see the number of
Apples that we are selling in Europe
at that price. Mostly, we are not
selling to companies, we are selling
to individuals.
DH What I am trying to assess is whether
it is a matter of affordability and
available money or awareness on
the part of the small business com-
munity of the possibilities of
computer systems.
It is probably a combination of
both of these things, David. But
no, I do not want you to have this
hang-up on the price. There was
another statement which you made
earlier that I did not answer. You
told me that the PET starts at £600
and Apple starts at £750 (I will not
mention the colour card because
the PET has no colour). Then you
say ‘Fine, let’s add a £200 black-
and-white monitor and then you
are at £950 versus £600.

All right, to add memory to the PET
you can.only add 16K to begin with.

AS I am going to break the rules, but
after all you are from Europe, and
Europe is our province. By April
of next year, you are going to see
a new model. I am not saying some-
thing that will replace Apple II, we
believe that Apple II will have a
life even longer than we anticipated
before. It is a very reliable and
powerful computer. We will an-
nounce an additional model with
a price up to twice that of the Apple
II and it will have many more
features than Apple II.

To give you an example, an absolutely
fully-fledged keyboard; a lot of
internal memory; an 80-character-
wide screen with text and graphic
combinations in colours; upper/
lower case, etc. It will be com-
patible at a software level with the
Apple II.

At the end of 1980 you are goig to
see, we hope, a totally innovative
product that will be a very good
business computer. This will be
based upon an entirely new archi-
tecture, not on the 6502. I want to
add that we have selected PASCAL
as the language that all our future
machines are going to support
primarily. All our future machines
are going to speak BASIC, FOR-
TRAN and maybe other languages,
but PASCAL is the language for us.

DH That is very interesting. I think that
the present very high level of interest
in PASCAL is well justified. It has
a similar ease of use as BASIC but
its structured elements make it a
much more sensible language .. .

AS .. . it is a little less friendly than
BASIC...

DH... . it is less friendly but then try
to key-in COBOL. It seems to be a
good compromise but it is very much
a language for experienced pro-
grammers.

Language of the future

AS It is the sort of language that a
lot of people believe is going to be
the basis of all the languages of the

with a particular model of the
Apple?

I am not sure it would be a particular
model of the Apple. I think we have
on the drawing board something
which is radically different from an
Apple; it would not be a cut-down
version of the Apple II. It has to
serve its own needs...

DH Do you see Apple sticking with

mos technology components for
the medium term?

We will certainly remain with the
6502 for the Apple II and for the
next version. After that an eight
bit micro has limitations that do
not permit the architecture that we
want to build.

DH Would you like to be more specific

there? Are you talkling about a lot
more memory or a lot more pre-
cision? Or both?

I am talking about two things. First
of all, we may not want to build a
machine that is based on register
architecture. That is the main phil-
osophical concept. The MOS
Technology 6502 is very nice but
it has addressing modes that are
not very useful. The 6809 is far
superior in terms of addressing
modes. You can do off-sets and
branches in much better fashion.

But | think the real question is do you

want to build the machine around
a register architecture or not? And
I think the answer is ‘no’!

DH We will see changes in the product

line approach generally in terms of
types of systems that you are
offering but also see what sound,
at the moment, to be quite radical
changes in the architecture. This
would be some years off?

This would be only 15 months off.
The machine that I am talking about
which for us is a totally innovative
machine is some 5% completed right
now, but the architecture is designed.
We hope that it is going to be a nice
machine for the user. O

PRACTICAL COMPUTING January 7980

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® Circle No. 183
83

A. C. Kilgour, who works at
the University of Glasgow’s
Computing Science Depart-
ment, describes what the
future holds for applied
computing graphics and
details some of the books to
read for further enlighten-
ment.

IVOR SUTHERLAND was the first to
demonstrate the potential of computer
graphics as a new means of man-machine com-
munication in the early sixties. Working at
MIT, his thesis Sketchpad, A Man-Machine
Graphical Communication System (MIT
1963)*created a big impression at the time and
a rapid expansion in graphics applications was
predicted. It was recently republished in book
form by Garland Publishing Inc, 545 Madison
Avenue, New York, NY 10022 ($18) and is
worth reading, especially by those new to the
subject who want to see how much, or how
little, progress has been made in sixteen years.

The predicted revolution following the
publication of Sketchpad was rather slow in
coming. Except in specialised high-budget
applications like aircraft and automobile
design, very litle progress was made in the first
ten years. With the benefit of hindsight, it is
not difficult to see why. Refreshed displays of
the kind used by Sutherland remained
expensive.

Support for such displays requires a
powerful processor dedicated to the graphics
user, who much of the time might be scratching
his head wondering what to do next. Perhaps
most important of all, programming graphics
systems was heavily device-dependent, so that
every new system had to be built from scratch.

It is only relatively recently that the long-
expected graphics boom has begun to take
place. As explained below, the largest single
factor has been the drastic reduction in the cost
of computer memory. Great strides have been
made in establishing a sound basis for graphics
programming. But moves towards standard-
isation have frequently been overtaken by
advances in hardware which introduce facilities
not catered for in the standard. In addition the
increasing moves towards realism in graphical
output have revealed problems which were of
no concern five years ago, when nearly all
graphical output was of the ‘‘line-drawing”’
variety.

Types of graphics device

As with ordinary character terminals, a
fundamental distinction is between hard copy
devices, which produce a permanent record on
a piece of paper, and soft copy or display
devices, where you can’t take the picture home
with you. For interactive graphics, some kind
of display device is almost essential, because of
the fast drawing speed and the ability rapidly to
extend or modify an existing picture.

Even with a simple printing terminal, quite
impressive ‘“‘greyscale’’ pictures can be
produced, particularly if overprinting is
possible. Figure 1 shows an example. Every
computer installation has its own collection,
kept to impress visitors or amuse the operators
when work is slack.

Although such pictures are mostly for
entertainment, their method of production is
of some interest. In effect the area of the
original picture is divided into an array of cells,
one for each print position on the device (for

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Figure |: Typical shaded picture obtainable on printing terminal.

PRACTICAL COMPUTING January 1980

example 132 x 66 on a typical line printer
page).

The ‘‘darkness’” (or ‘‘brightness’’) within
each cell, integrated over the area of the cell, is
measured and expressed on an integer scale
from 0 up to some maximum value, eg 3 or 15
(usually one less than a power of two). Then
for each non-zero value on this ‘‘grey scale’’, a
character or combination of characters is
chosen which approximates to the
corresponding darkness level. Printing these
for each position gives the required approx-
imation to the picture. Combinations of
characters using up to four over-printings have
been devised which give up to 127 different
grey levels on common printing terminals.

In the process described above, we convert
an ‘“‘analogue’’ picture, ie one with (in
principle) continuously varying grey levels, into
a digital representation consisting of an array
or ‘‘raster’’ of small numbers, one number for
each cell or raster position. The success with
which this process can be reversed, ie a
satisfactory representation of the picture
produced from its digital representation,
depends on the resolution of the grid (the
number of raster positions) and the number of
grey levels.

A minimum of 256 x 256 raster positions
with 16 grey levels (0 to 15) is required for good
quality reproduction of a TV-quality mono-
chrome picture. This is a lot of data (28 x 28
x 24 229 bits = 1 million bits or 128Kbytes),
exceeding the total memory capacity of most
micros and many minicomputers. It is only
because of the dramatic reduction in the cost of
memory that this form of picture representa-
tion now forms the basis of many low cost
graphics systems.

Mini-Explor is a package of Fortran sub-
routines for generating and manipulating
pictures represented as a grid of up to 140 x
140 cells, with four grey levels. It was devel-
oped by Ken Knowlton of Bell Laboratories,
and has been used for computer graphics
teaching, and for experiments in computer art.
The package consists of about 430 lines of
standard Fortran, and can drive any hard-copy
device capable of overprinting. It is not suit-
able for most VDUs, which allow only one
character to be drawn at each screen position.

For details of availability write to Ms Irma
Biren, Computing Information Service, Bell
Laboratories, 600 Mountain Avenue, Murray
Hill, New Jersey 07974. A minimum of 16K
bytes of memory is required to run the package
with a reasonable-sized calling program. It
provides a useful introduction to grey-scale
graphics if you already have a printing
terminal.

Plotters

Plotters come in many shapes and sizes. As
well as being used to produce ‘‘grey scale’
pictures as described above, a printing terminal
can also be regarded as a simple plotter. As
such, however, it suffers from two disadvan-
tages. The first is the limited resolution —
normally only 10 points per inch can be plotted
(printed) in the horizontal direction, and 6 per
inch in the vertical direction.

This means, for example, that only a crude
approximation is possible to a straight line.
Special graphic printing symbols, representing
short line segments at various angles, can
alleviate this difficulty to some extent, but the
results are still far from ideal.

The second disadvantage is that the
characters for printing have to be presented to

PRACTICAL COMPUTING January 1980

the terminal in line order, and usually also in
left-to-right order on each line (although it may
be possible to scan the same line several times).
It is not in general possible to move the print-
head back to a position on a preceding line.
Since a program-producing graphical output
may generate lines in any order, this means it is
necessary to hold in computer memory a
“‘map”’ of the page, with a representation of
what is to be printed at each position. Only
when the picture is complete can this map be
scanned to produce the printed picture.

Figure 2: Pattern produced on Diablo
Hitype printer with fine spacing.

On the daisy-wheel printers (eg Diablo
Hitype or Qume) which form a part of many
word processing systems, much greater
precision is usually available in positioning the
print head (typically 60 or 120 positions per
inch horizontally and 48 per inch vertically),
and depending on the type of paper-feed
mechanism, it may be possible to move
arbitrary distances back up the page as well as
down.

Although these refinements are intended to
facilitate typesetting applications, they allow
such a printer to be used for quite respectable
plotting applications, although since in general
lines must be generated by printing adjacent
dots, the output rate is slow. Figure 2 shows
a pattern produced on a Diablo Hitype I.

The simplest type of pen plotter is the “‘chart
recorder’ used on may measuring instruments.
Where the position of the pen is determined by
two independent analogue voltages, the term
**XY plotter’’ is usually applied. Such plotters
are available with a range of plotting areas.
Prices range from around £1000 upwards.

For a computer control some form of D/A
converter is required. Packaged versions with
built-in microprocessor performing line-
drawing and character generation are now
available for example from Hewlett Packard,
Tektronix and Houston Instruments, at prices
from £3000 upwards. The great advantages of
these plotters is their fast drawing speed

eS LE a ee ee ee

(typically 15-20in per second) compared with
the more conventional though more accurate,
incremental plotters where the pen is moved in
small fixed-size steps by two independent step
motors.

Figure 3 shows a pattern generated on a
Tektronix 4662 plotter. The pattern is a
Sierpinski space-filling curve, details of which
can be found, for example, in Wirth’s book
Algorithms + Data Structures = Programs
(Prentice-Hall 1976). The plotter is driven by a
1200-baud serial line, and plotting time was
approximately three minutes. The program to
generate such curves is very straightforward
provided you have access to a language which
supports recursion. In more primitive
languages, it is not so easy.

Displays

The cathode ray tube is still the basis of
nearly all currently available display devices. In
spite of the high voltages required, and its
relatively high power consumption, its
flexibility and dynamic picture modification
properties have not yet been rivalled. It is
cheap because of the mass market for domestic
television receivers, although this advantage
disappears for applications requiring high
precision or special phosphors.

The most common application of the CRT,
apart from the domestic TV set, is the VDU
(visual display unit) terminal. A typical VDU
will have 24 lines of 80 characters, though in
the hobby market terminals with a smaller
character capacity are common. The basic
VDU has the same limitations as a printing
terminal when regarded as a device for
graphical output, with the further disadvan-
tages of generally smaller page size and the
absence of overprinting — only one symbol can
be displayed at each character position.

However, many VDUs have direct ‘‘cursor
addressing’’, that is the ‘‘print’’ position can
be moved under computer control to any
nominated character position, described by its
line and column numbers. This permits
immediate output of randomly-generated
graphical elements, without the need to store
an internal page map.

Since the tube used in a VDU is very similar
to that in a domestic TV, it is fairly easy to add
colour without increasing the price too much.
The use of colour greatly improves the
subjective effect. It has been said that adding a
selection of four colours is better than doubling
the resolution on a monochrome display,
though in practice the extent of the improve-
ment depends on the type of picture being
drawn.

Many colour systems developed initially as
“‘mimic’’ displays for control systems are now
being sold as general-purpose graphics
terminals. Most of these can be regarded
essentially as colour VDUs, with a few
additional features to enhance the graphics
performance. For a good survey of the
operation technology and uses of VDUs, as
well as a discussion on the alternatives to the
CRT being investigated, see Visual Display
Units and their Application edited by Derrick
Grover, IPC Science & Technology Press,
1976.

Before proceeding to look in more detail at
the extensions of the VDU type of system
which offer true graphics capability and which
are becoming increasingly accessible to the
hobbyist market, it is as well to consider the
different categories of display devices which
are based on the CRT. The first major differ-

ence is between storage and refreshed systems.

On a storage tube, the picture once
“painted’’ on the back face of the CRT by the
electron beam, remains visible for up to an
hour without further action by the controlling
computer. Most storage tubes are of the
‘direct view’’ type (‘‘indirect view’’ systems
exist which use a small silicon target, the image
being enlarged and made visible by a TV type
scan conversion system), and Tektronix
manufacture all the available terminals of this
type.

The back face of the CRT in a storage tube is
coated with a ‘‘bistable phosphor’’ so that the
primary electron beam sets up a permanent
charge distribution as it ‘‘paints’’ the picture.
This distribution is made visible thereafter by a
secondary ‘‘flood’’ beam of low-energy
electrons, which reach the phosphor at the
viewing surface only at places where a path has
been ‘‘etched’’ for them by the primary beam.

For several years storage tube terminals
provided the only means of obtaining high
quality graphics at moderate cost, and there are
still many applications for which they are the
best solution. Prices range from around £2500
upwards.

Disadvantages of storage tube systems are
poor contast and the inability to modify the
Picture quickly (other than by adding more
information). This is because there is no
“selective erase’ capability: if a part of the
Picture is to be removed from the display, the
screen must be blanked out and the whole
Picture redrawn. Advantages are the high pre-
cision (750 x 1000 up to 3000 x 4000 approx)
and unlimited information content, subject of
course to overall resolution.

Refreshed displays

On a standard TV screen, the electron beam
is made to traverse the complete screen 60 times
a second, using a scan pattern like that shown
in Figure 4. During the left-to-right movement,
the energy of the beam is modulated according
to the external signal to give the required light
intensity at each point on the screen. On an
‘interlaced’? system, only half the available
line positions are visited on each scan, the line
spacing being twice the minimum. On alternate
scans the start position of the pattern is
displaced by one line space, so that lines missed
on the first scan are filled in on the second.

This has the important consequence that on
interlaced systems each position on the screen
is visited only thirty times a second, even
although the ‘‘refresh rate’’ is 60 times per
second. Because of the very short persistence of
standard TV monochrome phosphors,
horizontal lines tend to flicker very noticeably
when displayed on a standard monitor with
interlacing. For’ this reason such systems
usually use a monitor with the longer-
Persistence P39 green phosphor.

The method of traversing the screen on a
standard TV system is referred to as a ‘‘raster
scan’’, and displays based on such a system are
called raster scan displays. The need for
interlacing can be avoided if the resolution in
the vertical direction does not exceed 320 or so
lines, which allows standard TV phosphors to
be used. The characteristic property of raster
scan refreshed systems is that the complete area
of the screen is traversed every refresh cycle (or
every two refresh cycles on an interlaced
system). The refresh rate is constant, and
completely independent of the picture content.

The other major category of refreshed
display system is variously called ‘random

scan’, ‘calligraphic’, ‘cursive’ or ‘vector
drawing’ systems, although the last is
somewhat misleading, since raster-scan systems
can also draw vectors! The intention is to draw
attention to the fact that a raster scan display
can aiso fill areas.

On this type of display, which until recently
was almost universal in applications requiring
high quality or dynamic picture modification,
the beam moves in accordance with
instructions sent by the controlling computer,
rather than in a preset pattern. These instruc-
tions will typically be to draw a line or a point
or a character string.

Precision is usually 1024 x 1024 or higher,
and there are several intensity levels. The
complete list of instructions defining the
picture is called a ‘‘display file’’, and has to be
transmitted to the display at least 25 times per
second to ensure a flicker-free picture. Because
of this the display file is usually held in the
memory of the controlling computer, and is
accessed directly by the display using cycle-
stealing.

The number of vector inches that can be
displayed without flicker on such a display
depends critically on the speed of line drawing,
and because of this, and the high precision,
such displays are usually expensive. Never-
theless, prices have come down and perform-
ances improved recently, and basic systems are
now available starting at between £6000 and
£7000.

Frame stores

Returning now to the raster scan type of
refreshed display, the representation of the
picture is in terms of an array or raster of
picture elements, or pixels as they have come to
be called. The number of bits/pixels depends
on the number of grey levels, colours and
separately-addressable picture planes that are
provided. The part of the system which holds

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the information is called a frame store, or pixel
store.

A scan conversion system generates from the
frame store to a standard TV video signal at 60
frames/second. Any change in the picture
definition held in the frame store thus appears
on the screen almost instantaneously. The
problem in generating dynamically-changing
pictures is to update the frame store fast
enough.

The amount of information held in a frame
store is, by conventional standards, enormous.
Only the dramatic reductions in the cost of
memory have made the present situation
possible in which frame stores for 256 x 256 or
§12 x $12 precision are available at hobbyist
prices. The advantages of using standard TV
technology for the output end of a computer
graphics system have been obvious from the
start, but the storage problem has until recently
inhibited development of such systems.

There have been successful systems which
used a few adjacent tracks of a fixed-head disc
for the frame store. The investment in the disc
drive was economical provided a sufficient
number of terminals were required, so that the
per termina! cost was kept low. Typically a disc
with 100 tracks might support 25 terminals. If
the disc costs £15,000, it represents an
additional cost of only £600 per terminal. For
one-off systems, however, random access
memory is the only feasible solution.

The two outstanding advantages of raster
scan systems are the ability to fill complete
areas, rather than generate only line diagrams,
and the availability of colour at relatively little
extra cost. The specification of colour in the
frame store would seem to require many
additional bits per element. At the simplest
level, there could be a one bit for red, one for
green and one for blue. This would give seven
distinct colours, but the selection of colours
available would be the same for all pictures.

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Figure 3: Sierpunski space-filling curve (order 5).

PRACTICAL COMPUTING January 1980

Greater flexibility is obtained by having an
index whose entries are pointers to colour
definitions in a much larger table of possible
colours, held for example in ROM. The colour
specification in a pixel then selects an index
entry, which in turn specifies the colour. By
changing the contents of the index, the range of
colours can be changed, although the total
number of colours usable at any one time is still
limited by the number of colour bits in the
pixel.

A range of micro-compatible frame stores
with video output is now available for the
hobbyist market. These boards connect directly
to a standard micro bus such as the S100, or
interface to the bus of a mini such as an PDP
11 or Nova. An alternative is to purchase a
“‘packaged”’ terminal with serial interface for
attachment to any machine with a serial line
port.

Such a terminal will have its own built-in
microprocessor and frame store, and normally
will incorporate automatic line and text
generation (done by software of firmware in
the micro), graphics cursor control, and
perhaps also automatic curve generation and
area filling.

The advantages of such terminals are
considerable for those looking for an ‘‘off-the-
shelf’? system, but because of the packaging
there is a loss of flexibility in that the user
cannot normally access the microprocessor,
and the speed at which the frame stored can be
updated is limited by the speed of the serial
line. Except for applications where high
precision is important, raster scan terminals are
replacing storage tubes as the most common
low-cost graphics terminal for use with a time-
sharing system or stand-alone mini or micro.
Prices start at around £1600 for 256 x 256
monochrome terminals.

An interesting variation on the purchase of a
complete terminal is a ‘‘black box’’ which,
plugged between a VDU and the computer to
which it is normally directly connected,
converts the VDU toa 256 x 256 or 512 x 256
raster graphics terminal. The Sigma GOC 5200
is such a device (details from Sigma Electronic
Systems Ltd, Church Street, Warnham,
Horsham, Sussex), which is suitable for use
with most common VDUs. For ADM 3A
terminals, Lear Seagler offer the Retro-
Graphics RG512, which is a 512 x 256
resolution system.

Since VDUs are not normally interlaced, it is
not possible to obtain higher precision in the
vertical direction using only the VDU screen.
The Sigma GOC 5500 is a 512 x 512 system
which requires a separate monochrome TV
monitor for the graphics, while retaining the
VDU screen for normal alphanumeric output.
This has the advantage that the picture is not
overwritten by transient text message from the
computer.

Problems in raster graphics

Since raster systems produce output on a
more or less standard TV monitor, it is natural
to ask: Can a computer generate images from
internally-stored data which match the quality
of the images derived from TV signals? Here
there are two separate problems. The first is
that of static picture quality, and the second of
dynamic image modification. Solutions to the
first are availble, but a complete solution to the
second is not yet in sight.

You do not have to go very far with a low-
resolution raster scan display to hit some of the
limitations to picture quality, Lines which are
close to vertical or horizontal appear ragged.

PRACTICAL COMPUTING January 1980

There is severe flicker on horizontal lines if you
use an interlaced system with a standard TV
phosphor.

It is interesting that this effect is present on
every domestic TV screen, but is hardly ever
noticed because of the density of the picture
and general irregularity of the outlines. Worst
of all, spurious patterns may appear which are
not preent in the original pictures.

Figure 5 is a photograph of a pattern of
straight lines drawn on a 512 x 512 raster scan
display. Interference effects can be seen which
are not part of the original picture, but arise
because the lines are generated as a set of
discrete points.

These effects become even more marked
where shaded pictures rather than line
diagrams are produced. This so called
“‘aliasing’’ problem is discussed in a paper by
Crow inthe Communications of the ACM, Vol
20, No. 11, pp 799-805 (‘‘The Aliasing
Problem in Computer-Generated Shaded
Images’’). A solution based on filtering is
described in the paper, and the method is suit-
able for implementation in hardware. The
purpose of such a filter is to ‘smooth out’ areas
where there are sharp changes in colour or
intensity, without losing accuracy, using
information about points in the immediate
neighbourhood of the _ discontinuity.
Enhancements of this kind form an essential
part of any raster graphics system required to
produce high-quality shaded pictures.

The problem of generating dynamically-
changing images on a raster scan system with
frame store is severe. To move around simple
line drawings is not too difficult — only a small
part of the frame store needs to be updated. At
the other extreme, however, for a complex
shaded picture it may be necessary to rewrite
the complete frame store between each scan —
or during each scan if duplicate frame stores
are available and double-buffering is used.

Figure 5: Straight line pattern drawn on
512 x 512 raster scan display.

eS a eee Graphics an

Although techniques have been devised to
reduce the amount of data to be written, and
rewriting may be performed only every two or
three scan cycles, the data transfer rates require
are still enormous. For this reason, systems
designed for dynamic transformation of
shaded pictures have abandoned the frame
Store, and attempt to drive the display directly
from a higher-level picture description.

Prof Grimsdale’s group at Sussex University
is developing a system based on hardware
modules known as zone management
processors. Each module is responsible for the
display of one or more plane polygonal areas
(zones) of constant colour and intensity. By
giving each zone a priority associated with its
distance from the viewer, the problem of
hidden surface removal can be dealt with
directly by the device. The method of assigning
zone priorities is described by P. J. Willis in
“A Real-Time Hidden Surface Technique’
Computer Journal, Vol 20, No 4 (November
77). pp335-339). This system exploits the
redundancy present in many shaded pictures,
where large areas may have the same brightness
and colour.

The number of ZMPs required for a
particular picture depends on the complexity of
the picture — each ZMP can handle up to 16.
zones. Since the zone definition is very
compact, and the picture is generated directly
from the definition, dynamic picture modi-
fication is possible merely by updating the
specification of all zones which are affected,

Adrian Thomas of Prof Heath’s group at
Heriot-Watt University has built a prototype
colour display which uses a different approach.
Each object in the picture. is described as a
combination of planes, which are not
necessarily parallel to the viewing surface, and
which potentially may have variable colour or
texture. Hidden surface removal is performed
by the device itself, without the need for prior
analysis of the scene.

The design is modular, so that the total
number of surfaces that can be handled can be
increased merely by adding further modules.
Dynamic picture modification is again possible
merely by updating the definition of each
affected plane (currently 90 bits for each
plane).

Both of these designs use concurrency in
specialised ways to achieve enhanced perform-
ance. At Glasgow University we are
investigating the application of data-flow
architecture, which offers a more general and
unified approach to hardware concurrency, to
the problems of dynamic display design.

The aim of these and other research efforts is
to produce a system capable of real-time colour
display of simulated scenes, with a picture
quality as good as that on a conventional TV
picture of a real scene. Among the many
potential uses of such a facility are flight
simulation, animation and computer-assisted
instruction.

Graphics software

The variety of graphics software that has
been written is enormous, much of it intimately
tied to particular computer systems or display
devices. In what follows only a few of the more
commonly availble packages are referred to,
and some methods described which are of
relevance to those writing their own software.

The Mini-Explor package for greyscale
output on a printing device has already been
mentioned. A general-purpose package of
Fortran subroutines for 2D and 3D plotting

called Simpleplot is available from University
of Bradford (contact Lawrence West,
Industrial Liason Manager, University of
Bradford, Bradford BD7 1DP).

The package is device-independent and fairly
easy to set up for any particular output device.
The Ghost package, developed by Larkin,
Prior and others at Culham Laboratory, has
been implemented on a wide range of
machines, and is very popular in universities. It
offers comprehensive 2-D facilities, including
drawing of circles and conics, curve fitting nd
typewriter simulation, and is available for a
modest sum from Culham.

Gino-F is a powerful package of Fortran-
callable procedures for 2-D and 3-D graphics,
including graph plotting, viewing and
modelling transformations, surface description
and graphical interaction. It was developed
initially by P. A. Woodsford at the Computing
Laboratory, Cambridge, and is now marketed
for a wide range of mini and mainframe
computers by the Computer-Aided Design
Centre, Madingley Road, Cambridge.

Another commercially-available package is
Disspla, marketed in the UK by SIA Ltd, 23
Lower Belgrave St, London SWI. It has
particularly powerful facilities for the
generation of graphs and maps, and is widely
used by geographers and cartographers.

For microprocessors driving a simple raster-
scan display, many manufacturers offer
graphical extensions to Basic, but as yet there is
little in the way of graphics subroutine
packages. An exception is the Fortran package
for the Vector High Resolution Graphics
Board (S100 compatible) offered by Video
Vector Dynamics Ltd, 97 Dornal Avenue,
Glasgow G13 4JH (tel 041-339 6782). This
company also supplies applications software
for a variety of mini- and micro-based graphics
systems.

Originally developed for computer-assisted

learning applications, the GUSC Graphics
Package offers general facilities for graphical
output and interaction. Two versions are
available, onein Fortran and one in Basic, and
supported devices include the Computek 300
raster scan display and the Tektronix 4010
storage tube terminal. Enquiries about the
package, and a variety of CAL material built o
it, should be directed to R. Lewis, Chelsea
College, Pulton Place, London SW6 5PR. The
book by J. McKenzie et al, Jnteractive
Computer Graphics in Science Teaching (Ellis
Horwood 1978) gives details of the develop-
ment of the package and its uses in education.

The proliferation of different systems and
packages has led to attempts to impose stan-
dardisation on graphics software. In the US
the Graphics Standards Planning Committee
of the ACM has proposed a standard graphic
package known as the ‘‘Core’’ system. Many
groups have developed or are developing
implementations of the standard, and it is
possible that some of these may become
available in the UK in the near future. The
“Core’’ system is comparable in power to
Gino-F, though differing in philosophy and
many points of detail. Extensions to cater for
the properties of raster-scan display are
currently under discussion, and it is probable
that a revised standard will be defined in the
near future.

In the UK, the British Standards Institute
has set up a working group (DPS13/WGS) on
graphics standards, chaired by D. L. Fisher of
the Computer Laboratory at the University of
Leicester. The group has sent detailed
comments on the Core system to the US
standards planning committee, and has
considered other possible standards such as
Gino and the German AGF system.

When graphical output is to be generated on
devices capable only of plotting points (such as
a simple raster scan display with no built-in

Figure 6: Pattern of ellipses (“snail”) generated using integer arithmetic.

line-drawing capability) or of drawing small
increments, such as a conventional incremental
drum plotter, algorithms are needed to select
the best points or increments to approximate to
a given straight line or curve. For a straight line
between two given points on the grid of
accessible device positions, an incremental
algorithm is possible which requires only
addition and subtraction during the generation
of the points or steps, and which is guaranteed
to terminate at the correct end-point. If you
don’t know the algorithm, you can have a lot
of fun working it out for yourself.

It is analogous to the method of working of
the hardware device known as the digital
differential analyser. This approach can be
extended to generate simple curves. For further
details see, for example, /nteractve Computer
Graphics by Walker, Gurd & Drawneek,
(Edward Arnold 1976) pp.108-114.

Incremental methods of curve generation are
desirable for efficiency on machines without
hardware floating point, but they pose certain
problems in obtaining uniform smoothness,
for example in highly-eccentric ellipses, and in
guaranteeing accurate termination, due to
accumulation of small errors. An alternative
method, which uses only 16-bit integer
arithmetic, and employes table lookup for
trigonometric functions, has been developed by
Colin Prosser at Glasgow. Full details are in his
MSc thesis (Graphical output methods and
their relation to display system design,
Department of Computing Science, October
1979). Figure 6 shows a drawing consisting
entirely of ellipses generated using the method.

Sources for further reading

In this article it has been possible to touch on
only a few aspects of computer graphics, For
those wishing to delve more deeply, the book
by Newman and Sproull Principles of
Interactive Computer Graphics, McGraw Hill,
(second edition) 1979, or that by Giloi,
Interactive Computer Graphics, Prentice-Hall,
1978 both provide an excellent coverage of the
field.

The mathematical material required for 2D
and 3D transformations, and curve and surface
description, is well covered by Rogers and
Adams in Mathematical Elements for
Computer Graphics, McGraw-Hill 1977.
Relevant journals include Computer Graphics,
published quarterly by the ACM Special Inter-
est Group on Computer Graphics
(SIGGRAPH), Computer-Aided Design
published by IPC Science and Technology
Press Ltd, and Computer Graphics and Image
Processing published by Academic Press.

Conclusion

Computer graphics, after many years of ex-
pectancy, is at last about to come of age. As
with other branches of computing, this is due
at least as much to technological advance as to
improvements in graphics software. The
software, indeed, always seems to be one or
two steps behind the hardware. This is particu-
larly noticeable in attempts to define
standards.

However, although it can be fun sometimes,
there is really no point in everyone attempting
to re-invent the wheel. Very soon the
combination of powerful but inexpensive
graphics hardware with widely available
standard software will sllow programmers and
designers to concentrate on the application of
graphics. where there remain a wide range of
exciting possibilities which are only now
beginning to be exploited.

PRACTICAL COMPUTING January 1980

ps ee SS |

Standard software can give users a new flexibility with...

Transfer of programs between
two operating systems

In this article Dr John Lee and Timothy Lee show how you may discover exactly how
North Star BASIC programs are stored both in core (memory) and on disc. A similar
approach may be used for other BASIC interpreters on other machines. Once you
have gained an insight into the method of Storage, it becomes possible to carry out
tasks which carinot usually be performed using software provided by the manufact-
urer. This provides a general method for the transfer of BASIC programs into ASCII
characters which facilitates the transfer of programs between different machines. The
general method is developed into a BASIC progtam which will convert BASIC
programs from the North Star operating system to CP/M files.

A LINE of a BASIC program is not stored as the set of ASCII
characters which were typed in. Instead, it is automatically con-
verted into a thore compact form which econoinises on the
amount of memory used and results in faster execution.

Firstly the line number is converted ftom decimal into a two-
byte (16-bit) binary number. Since the largest number which can
be stored in 16 bits is 2! — 1, this restricts the largest acceptable
line number tyo 65535. The first byte contains the eight low order
binary bits and the second byte contains the eight high order
binary bits.

Storage characteristics

In addition any other liné number which appears in the line, for
example after a GOTO, THEN, RESTORE or EXIT, is similarly com-
pacted into two bytes and is preceded by a byte which indicates that the
following two bytes form a binary line number. The special byte has the
decimal value 154, as discussed later.

The remainder of the line (including spaces) is stored in ASCII
characters, one character to a byte, except for all of the reserved words
such as LET, FOR, COS, SQRT, each of which is compacted to a unique
number stored in a single byte. It is worth noting that decimal constants
are stored exactly as typed in (as ASCII characters), rather than in binary
coded decimal which is the form used during calculations.

When a constant is used ina calculation at run time, it must be con-
verted from ASCII to BCD form each time the line is executed, hence
faster running code can be obtained by setting a variable equal to the con-
stant once at the beginning of the liné prograni, and subsequently using
the variable.

The end of the line is denoted by one byte containing the ASCII
character for carriage return (decimal value 13). The whole line is
preceded by a single byte which indicates in binary the total number of
bytes in that particular line including both this byte and the carriage
return.

This is what a line looks like:

length

line number in
of line,

nin

binary

n—4 bytes comprising ASCII
characters and compacted
reserved words.

The line number 500 becomes 00000001 11110100 and is stored
lower eight bits first as shown.

After all of the lines have been stored, the end of the file is indicated by
a marker which is a line one byte long containing the binary value 1. Pro-
grams are stored in an identical manner in core and on disc.

PRACTICAL COMPUTING January 1980

For example the line 500 PRINT A is stored:

decimal 8 |decimal 244 >i

stored as

00000100 }11110100 } 00000001
Special characters for reserved words

The 128 characters defined by the ASCII set (which comprises
the digits 0-9, upper and lower case letters, arithmetic operators,
other printing symbols and control characters) are stored as the
binary equivalents to the numbers 0-127 inclusive. North Star
BASIC uses the binary equivalents of the decimal numbers 128 —
255 inclusive for the special characters which are the compacted (1
byte) form of the reserved words.

During the evolution of North Star BASIC, the meanings of a few of
the decimal numbers between 128-255 have been changed. In particular
the words CREATE, DUMP and NULL in release 3 have compacted
forms which correspond in release 4 and 5 to AUTO, MEMSET and
NSAVE respectively. This is less serious than it at first appears, since
these could only occur in REM statements.

By inspection of individual bytes of a BASIC program in core, using
the EXAM function (which is similar to PEEK on some machines), it is
possible to discover what some of the commonly occuring byte values in
the range 128-255 actually correspond to. For example 128 ! LET, 130 !
PRINT, and 146 is ! corresponding to the shortened form of PRINT.

Since PRINT and ! are both stored as one byte, using ! does not save
core but does of course reduce typing. A simpler and more systematic way
of finding the meanings of the characters 128-255 is to use the following
program.

10 CREATE “woRDS", 4, 2

20 OPEN #0%2, "WORDS"

30 FOR I = 128 TO 255
WRITE HO, &6, &1, 80, &32, 81, &13
NEXT I
CLOSE #0
CHAIN “WORDS

carriage
return in
binary

Notes on program wordlist
Line
10

Function

Creates an output file called WORDS, of size 4 blocks (1K) and
type 2(BASIC PROGRAM).

Opens file WORDS as device #0. The %2 indicates the file is
of type 2.

Start loop for values of I from 128 to 255.

Write to device 0 (file WORDS) the six byte values: 6, 1, 0, 32, I,
13. This resembles a BASIC line. The 6 specifies the number of
bytes in the line. The I and zero together represent a line number
of value I. The 32 is an ASCII space. The next I is interpreted as
a reserved word and the 13 is a carriage return.

End of loop.

Closes device#0 (file WORDS) and leaves an end of file marker

30
40

(control/A).
Replaces program WORDLIST by newly created ‘program’
WORDS.

When this program is run, a disc file called WORDS is created of length

4 blocks and type 2 (BASIC file). 128 lines of output are written to the

disc file in the same format as described for a BASIC program previously.

At the end of the program the CHAIN command replaces the program in

core with the pseudo BASIC program called WORDS which has just been

produced. Very early releases of BASIC lack the chain function, and the
last line of the program should not be typed, but instead the command

LOAD WORDS should be typed after the run. All releases of BASIC
report a FUNCTION DEF ERROR and for the moment this will be
ignored.

The command LIST should now be typed. This produces a table of the
numbers 128-255 together with their associated reserved words — for
example

128 LEF

129 FOR

130 PRINT

131 NEXT

Note the following points:

. The number 155 does not appear in the table. This is because the
number 154 corresponds to the line number marker which precedes
embedded line numbers, which was mentioned earlier. The word
corresponding to 155 is CHAIN, and this appears twice on line 154.

. A number of commands also appear as reserved. words. These include
RUN, LIST, BYE, etc. and appear from 160-175.

. Some of the numbers, eg 188 and 190, appear to be undefined whilst a
few others, eg 189, 199, 232 and 235, translate to the words B!VW, U!,
+; and PYDM, for which we have found no meaning. This should
provide a challenge for North Star enthusiasts — who can be the first to
explain any of them.

. Thecodes for the arithmetic operators: * + —/ = and( are stored
as numbers between 224 and 246. Should these symbols be stored in
Holleriths (strings), they are stored as ASCII characters between 40 and
94. The code thus indicates the context and meaning of the character.

. A further complication is that in release 4 BASIC all of the codes 233,

243, 245, 250 and 254 translate to = signs, in addition to the ASCII 61

character. An exhaustive check of 30 BASIC programs showed that

only 245 was actually used for equality. A similar situation exists for
the signs + and and 227 and 246 respectively appear to be used for
arithmetic.

It appears that only the ASCII value of 41 for ) is used regardless of

its context.

Conversion of compacted BASIC line

It may at first seem strange that a program is needed to do this
since the LIST command performs this function. LIST can only
output to a peripheral device such as a terminal, VDU or printer,
and a routine is needed if the output is to be stored on disc or
directly in core. The steps in a general routine would be:

1. Read the byte containing the length of the line and ignore it.
2. Read the two bytes containing the line number in binary. They are

converted into a decimal number and each individual digit is then out-

put as an ASCII character.

3. Subsequent bytes are read in one at a time. If the byte corresponds
to an ASCII character (decimal 0-127) it is output unchanged. There is
just one special case — decimal 13, which corresponds to carriage
return, is followed by a linefeed (decimal 10) and marks the end of the
line. Bytes with decimal values 128-255 correspond to reserved words,
and vary from machine to machine. The decimal value can be con-
verted into the corresponding reserved word by using a look-up table,
and the characters in the word are output in ASCII.

. Embedded line numbers must be identified, On the North Star they are
preceded by a byte containing decimal 154. The two bytes following are
converted to a line number as in step 2.

5. The end of file marker must be detected. On a North Star this is

control/A and on CP/M it is control/Z.

Modus operandi

CP/M requires continuous memory addresses starting at 0. Under this
system, transient programs are stored starting at 100 hex. A program

residing in memory starting at 100 hex can be copied into a CP/M disc-
file using the SAVE command. If another operating system loads an
ASCII file into core starting at 100 hex it is possible to change the operat-
ing system to CP/M without destroying the information in core. The
SAVE command will copy the contents of core into a CP/M disc file, thus
completing the transfer. This method is crude and long — but it works!

A neater solution for the transfer of a file is to have a program which
reads a compacted BASIC file, expands it into ASCII form writing the
output to memory starting at 100 hex. To complete the transfer, CP/M
must then be loaded, and the memory contents SAVEd onto disc.

Memory requirements

CP/M requires a minimum of 16K for soft-sectored disc
versions and up to 4K extra for hard-sectored disc versions. This
memory must start at location 0. The neat solution described
above requires in addition memory for the normal disc operating
system, and the program which converts to ASCII. Should the
conversion program be written in BASIC, then space is also
required for the BASIC interpreter.

In the particular case of converting North Star BASIC to a CP/M file,
the North Star disk operating system occupies 2.5K starting at 8K (2000
hex), BASIC occupies about 12.5K starting at 10.5K (2A00 hex), and the
BASIC conversion program occupies about 4K from 23K to 27K.

approx approx approx
10.5K 23K 27K
NORTH |
STAR Conversion
program
0 8K 16K 24K 32K
|
Minimum | Transient . Extra
CP/M minicyt Popeen! Operate for hard Unused
area system =
system discs
ris
100hex 20K

Memory maps, CP/M and North Star

The diagram above shows that if the North Star conversion program
uses locations 100 hex to 8K for the ASCII output from the conversion
program, then the CP/M operating system can subsequently be loaded
without overwriting this region. The ASCII text can then be SAVEd using
CP/M. This limits the size of the ASCII program produced to 7%4K since
a larger program will start to overwrite DOS, which results in the BASIC
conversion program crashing. This size limit is not in practice a serious
limitation. Not many programs exceed this size, and those that do can be
copied in two or more parts, and the resulting CP/M files merged into a
single file using PIP.

If insufficient memory is available to perform the ‘neat’ transfer above,
the ‘crude’ method can be employed. Sufficient memory must be avail-
able to hold DOS, BASIC and the conversion program. The ASCII
output is written to a disc file under the original operating system. BASIC
can then be dispensed with, and the memory re-configured to start at 0.
DOS is then used to load the ASCII disc file starting at 100 hex. CP/M is
loaded, and the memory contents SAVEd on a CP/M disc as described
earlier.

Dr John Lee and Timothy Lee will continue to contribute articles on software to Practical
Computing during 1980, concentrating on improving readability.

PRACTICAL COMPUTING January 1980

SS + i EE S75 cis ia

Automatic transfer North Star — CP/M files

A program is described which uses the ‘neat’ solution and
converts North Star BASIC files to CP/M files. Because of the
wide variety of dialects which exist in BASIC, some minor
program changes will be almost inevitable before a program
transferred in this way will run. In an attempt to minimise such

DIM F460), C820), AS(20) i i i i :
a ek difficulties the conversion program makes the following changes:
Foe FILECFS) 1. The North Star line separator backslash is replaced by the more usual
If f © 2 THEN 120 .

If fF > = 1 THEN 80 colon: oft j
PRINT "FILE '", F$, "* DOES NOT EXIST!” 2. The character ! used as an abbreviation to the word PRINT is replaced
GOTONeO by the word itself.
PRINT “NOT A BASIC TYPE 2 FILE" . H
PRINT "TYPE "RETURN? TO CONTINUE” 3. EXIT statements are used to jump out of loops in North Star and Xitan
INPUT AS disc basic. The statement is not used by most other BASICs and so the
If AS <> "" THEN 20
OPEN #OXF, FS program replaces the word by GOTO.
PAINT ue MANY SOURCE LINES TO BE SKIPPED BEFORE OUTPUT STARTS" 4. The words EXAM and FILL are changed to the more common PEEK
IF L1 <0 THEN 130 and POKE.
FORT = 170 U1 5. The function for square roots SQRT is changed to the more widely
READ #0, &L
IF L = 1 THEN 630 used SQR. : :
90 FOR J = 2 TOL The first of these changes is programmed at line 320 in the conversion
eDAIREAD JHO,UEN rogram. The remainder of the changes are accomplished by storing the
NEXT J ls : i hoy
NEXT I new word rather than the old word in the list of reserved words in lines
ae 850 — 1000. (These lines are based on the output of the program WORDS
READ WO, &L described earlier).
IF L = 1 THEN 710
Lie uted
GOSUB 540
READ #0, 8A =
TE A > 127 peenyaOD Notes on the Conversion Program
IF A= 92 THEN A = 58
FILL P, A = a aa
Pepe) Lines Function
Fee Sea ate neO 10—120 Find name of input file, and check that it exists and is a
, :
Pepe BASIC (type 2) file.
} Bee ag 2 S000 THEN 660 130 — 220 Find how many tines to be skipped. This is normally 0, but
400 TF A= 154 THEN 510 is used to segment a large program.
me RESTORE sd8 Tha 230 — 240 Set number of lines processed to 0, and output pointer to
430 READ AS 256 (decimal), ie 100 hex. tay
2 _— 250 — 260 Read a byte from input file and check if it is the end of file
460 FOR T= 1 TOA mark. :
470 FILL P, ASCCAS(I, 1)) 270 Increment number of lines processed.
pee eer 280 Call subroutine to sort out line number.
500 GoTo 2 290 Read the next byte from input fil
500 GoTo 290 ead the next byte from input file.
2 oe ae 300 Jump if it is a reserved word.
530 REM SUBROUTINE TO SORT OUT LINENUMBERS 310 — 320 Change 4:
i Pee ey 9 330— 340 Output ASCII character and move pointer.
CS = STRSCC) 350 — 370 Check if character was carriage return, and if so output
FOR I = 1 TO LEN(CS) .
ries De 380 iriga d ASCII is nearly full
FILL P, D ump if memory used to store is nearly full.
ae : 390 Go back to read the next line.
RETURN 400 Check for special character indicating an embedded line
PRINT "THERE ARE NOT", L1, " LINES IN THE FILE!” number P 8
PRINT "NO OUTPUT PRODUCED" . .
stop 410—440 Read through data list to obtain the appropriate reserved
PRINT "MEMORY BUFFER BETWEEN CP/M AND NORTH STAR DOS NEARLY FULL” d "
PRINT “OUTPUT STOPPED AFTER", L1, " PHYSICAL LINES” word.
PRINT "LAST LINE NUMBER OUTPUT WAS", C 450—500 Output reserved word character by character.
Pp
PRINT "OUTPUT SECOND PART AS A SEPARATE JOB AND MERGE FILES WITH PIP" 510 520 Call subroutine to sort embedded line number
PRINT = ‘ : r "
FILL P, oe 530 — 620 Subroutine to read to bytes corresponding to a binary line
Neste mE f= 1) 2 "," THEN 750 rise convert to decimal and output as individual ASCII
FS = FS(1, F = 2) characters.
i f 56), "", FS, ".BAS" ;
ee ‘BOOT UP WITH CP/M AND TYPE SAVE", INTCP / 256) BAS 630 — 700 Warning messages.
SEP eke EATTRCTRNCED ITM RUSD 710 Outputs CP/M end of file mark (control/Z).
REM 5 \ CHANGED TO ":" 720 — 750 ‘Prints instructions on how to save the ASCII contents of
oy Sh via pee ecm
REM seeee EXAM CHANGED TO PEEK 850— 1000 Data list of reserved words obtained using the program
REM e#eee SQRT CHANGED TO SQR WORDLIST.

“END,
"GOTO"

) “EUSE",
PILE",
“ant
*uLEN", “CALL, “RND", 4"

In a subsequent article we will show
how the spacing on a North Star BASIC
line can be changed to improve its read-

c
, "LOG", "EXP", “TYP™

ability, but the ideas involved are
applicable to several other systems.

PRACTICAL COMPUTING January 1980 91

Logic board redesign

MIKE LAKE is going to continue to keep
us informed about the PET and the IPUG
which, he tells us, has decided to employ a
part-time assistant to deal with the
administration and has set itself a target
for membership of 1000 by early 1980.

Mike has been using the new 32K
business PET since Easter and the 2040
disk drives since late May and has these
comments to make:

The new ‘‘big’? PETs contain a re-
designed logic board that has sockets for
up to 32K of on-board RAM. The ROM
chips containing the MICROSOFT Basic
and the CBM operating system are on the
main logic board and have been rewritten
to cure the faults present in the first
ROMs, and to expand the facilities of the
operating system.

The array limitation of a total of 256
elements has been removed, the limit now
being determined by the amount of
memory you have available. Similarly the
problems with writing to and reading
from tape have been cured, so that data
files can now be kept with a far higher
level of reliability, though, as before, the
read/write heads of the tape units must be
kept clean and regularly degaussed.

The redesign of the logic board has also
cured the ‘‘snow’’ problem associated
with POKEing the screen RAM; games
designers will be delighted with this
amendment!

Still on the board, the IEEE and user
port connection are unchanged but the
two cassette unit connectors are reversed;
drive | is now at the rear of the PET and
drive 2 is inside (there is now no built-in
cassette unit).

The memory expansion connector, now
of pin rather than edge type, allows not
only additional memory to be added to
the PET, but also the addition of
memory-mapped devices, disks, S100
adapters (BETSI) etc.

An interesting point there is that the
main board contains sockets for extra
ROM chips to be plugged in and already
PETSOFT are importing the PET
TOOLKIT ROM to expand the facilities
available in Basic.

This extra memory space, not available
to Basic programs, could also be used by
extra RAM memory on the memory
expansion port. An extra 12K here would
allow machine code systems to be loaded
at the beginning of the day and remain
there until the PET is turned off —
perhaps a manufacturer would like to take
this suggestion up?

A plea here: will a// manufacturers of
PET-compatible hardware please
remember that since a user may wish to
add more than one device to the PET. All
plug-in items should include a parallel
connector. IEEE devices are a special case
— see the discussion below about the 2040
disk drives.

All in all, the 32K PET has been a
dream to work with; with the new

software available for it, it certainly rates
' as a leading contender for the business

market. On the software side, there is a
problem. The new ROMs are not fully
compatible with the old ones; programs
written in standard PET Basic will work
perfectly with both ROMs, but those that
do any PEEKing or POKEing in the first
1K of memory will have problems, as all
the addresses have been changed to speed
things up. Most suppliers of software now
have versions of their programs suitable
for both sets of ROMs, so be sure to
specify exactly which machine you hve
when you are sending in an order.

Rockliff lock-up

M. VALENTINE has been using his PET
2001/8 with a Rockliff PR40 printer. It is
operated via the parallel user port using a
machine code subroutine supplied by
Rockliff. This is resident in RAM IF@@ to
IFE®@. It is called by the USR function.

All went well until I acquired a PET
2040 Dual Disk Drive. In order to work
the drive, the new PET ROMs are
required, as fitted to the 32K PET. When
the Rockliff routine was tried with the
new ROMs the machine locked up.

On decoding the Rockcliff program, it
became clear that the problem was due to
changes in locations of various functions
on ZERO page. By referring to the PET
manual and by using the listing in
Practical Computing (September 1979) I
managed to write a modified machine
code program.

The modified program requires 256
bytes, one less than Rockliff’s ‘old’
program. Rockliff’s program for the 32K
PET requires 514 bytes. Here is a list of
changed memory locations of significance.

ZERO MEMORY MAP

Old ROM New ROM
From To FromTo Description
000 000

8 4C Constant (6502 JMP instruction).

001-002 001-002 USR Function address lo-hi.

003 014 Active J/O Channel number.

004-007 _

008 017 Line number storage before buffer.

009 018 $2C Constant (special comma for
INPUT process).

010-089 512-591 BASIC input buffer (80 bytes).

090 003 General counter for BASIC.

091 004 $00 used as delimiter.

092 005 General counter for BASIC.

093 006 Flag to remember dimensioned
variables.

094 007 Flag for variable type: 0 = numeric;
1 = string.

095 008
096 009

Fiag for integer type.
Flag to crunch reserved words
(protects *’ & REM).

097 010 Flag which allows subscripts in syntax.

098 011 Flags INPUT or READ. ©

099 012 Flag sign of TAN. .

100 013 Flag suppress OUTPUT (+ normal;
— suppressed).

010 019 Index to next available descriptor.

102-103 020-021 —_ Pointer to last string temporary lo, hi.

104-111 022-029 Table of double byte descriptors which
point to variables.

112-113 030-031 ~— Indirect Index | lo,hi.

114-115 032-033 Indirect index 2 lo,hi.

116-121 034-039 Pseudo register for function operands.

122-123 040-041 — Pointer to start of BASIC text are:
lo, hi byte.

124-125 042-043 Pointer to start of variables lo,hi byte.

126-127 044-045 — Pointer to array table lo,hi byte.

128-129 046-047. —_- Pointer to end of variables lo,hi byte.

130-131 048-049 — Pointer to start of strings lo,hi byte.

132-133 050-051 Pointer to top of string space la,hi byte.

134-135 052-053. Highest RAM address lo,hi byte.

136-137 = 054-055 = Current line being executed. A zero in
136/054 means statement executed is a
direct command.

138-139 056-057 ee no. for continue command lo,hi

yte.

140-141 058-059 Roney to next statement to execute
o,hi.

142-143 060-061 Data line no. for errors lo,hi.

144-148 062-063 Data statement pointer lo,hi.

Locations not specified are used but have
no.clear one function definition.

Old ROM New ROM

FromTo FromTo Description
146-147 064-065 Source of INPUT lo,hi.
148-149 066-067 Current variable name.
150-151 068-069 Pointer to variable in memory.
152-1§3 070-071 Pointer to variable referred to in
current FOR-NEXT.
154-155 072-073 poly to current operator in table
0, hi.
156 074 Special mask for current operator.
157-158 075-076 Pointer for function definition lo,hi.
159-160 077-078 = Pointer to a string descriptor lo,hi.
161 079 Length of a string of above string.
162 080 Constant used by garbage collect
routine.
163 081 $4C Constant (6502 JMP instruction).
164-165 082-083 Vector for function dispatch lo,hi.
166-171 084-089 Floating accumulator no. 3.
172-173 090-091 —_ Block transfer pointer no. 1. lo,hl.
174-175 092-093 —_ Block transfer pointer no. 2. lo,hi.
176-181 994-099 Floating accumulator no. 1 (USR
function evaluated here).
182 100 Duplicate copy of mantissa of FAC
no. |.
183 101 Counter for no. of bits to shift to
normalise FAC] .
184-189 102-107 Floating accumulator no. 2.
190 108 Overflow byte for floating argument.
191 109 Duplicate copy of sign of mantissa.
192-193 110-111 Pointer to ASCII rep of FAC in
conversion routine lo,hi.
194-199 112-117. CHRGOT RAM code. Gets next
character from BASIC text.
200 118 CHRGOT RAM code regrets current
characters.
201-202 119-120 Pointer to source text lo, hi.
203-222 = -121-140 = Next random number in storage.
224-225 196-197 _ Pointer to start of line of cursor
location lo,hi.
226 198 Column position of cursor.
227-228 199-200 reaper purpose start address indirect
0, hi.
229-233 201-204, General purpose and address direct
180 lo,hi.
234 205 Flag for quote mode on/off.
238 209 Current file name length.
239 210 Current logical file number.
211 Current primary address.
241-242 = 212-213. = Current secondary address.
243-244 «214-215 — Pointer to start of current tape buffer
lo,hi.
245 216 Current screen line number.
217 Data temporary for 1/0.
247-248 = 251-252 _—_— Pointer to start location for O.S. lo,hi.
249-250 216-219 Pointer to current file name lo,hi.
251-254 — Unused?
255 -

24-hour clockface

RON GEERE, Editor of IPUG News-
letter, tells us he wrote this program for a
working ¢lockface in a total of three hours
(see right). j

62 bytes on bottom are used for error
correction in tape reads. Also, buffer for
ASCII when BASIC is expanding the
FAC into a printable number. The rest of
page 1 is used for storage of BASIC
GOSUB and FOR-NEXT context and
hardware stack for the machine.

PRACTICAL COMPUTING January 1980

The CBM 2040 disk drive

AFTER MONTHS (who said ‘“‘years’’?)
of waiting, the 2040 disk drives are
becoming available in reasonable quan-
tities. The last six months has seen large
sales of COMPUTHINK and NOVA-
PAC drives, so the CBM ones have a lot
of competition.

To set the bad things out of the way
first, let me say that there are problems
with the 2040 units. The original drive that
I saw at the beginning of the year had heat
problems; Commodore knew of this, but
have done nothing about it. The versions
that have arrived on the market all have
their heat-sink mounted on the main logic
board and facing downwards! Commo-
dore have gone some way to solving this
problem by changing the design of the
case cover to allow a greater circulation
of air.

Even so, my own drives suffer no ill
effects from this heat, though I know of
more than one member of IPUG who has
to have a fan blowing over the rear of the
unit to prevent read errors on drive 1.

The drives offer up to 342K online,
171K per diskette, with up to five files
open at the same time. Here the unit really
comes into its own with its own 6502
processor, 6522 I/O controller, 4K of
RAM and operating system in ROM. It is
potentially very powerful.

Now we come to the other problem;
Commodore documentation, or lack of it!
The original user’s manual can only be
described as appalling, so bad in fact that
Commodore UK refused to support
random-access files because they
themselves were not certain how the
worked! The latest version of the manual
is a tremendous improvement — with
luck, the quality of all Commodore docu-
mentation will now improve dramatically.

The handling of files on the drives is
indeed quite complex — certainly
nowhere near as easy as on the COMPU-
THINK and NOVAPAC drives, but is not
beyond the understanding of a competent

Ron Geere’s speedy clockface programme.

G@ REM ANALOGUE CLOCK BY R.T.GEERE

programmer. Sequential files present few
problems but the first time user should
beware of random-access files — they are
hard!

The real strength of the 2040 lies in its
extreme flexibility. Once mastered, its
controlling instructions from Basic allow
you quickly to set up sequential and
random-access files. The RAM inside the
unit means that buffers do not take up
any of the PE’s memory and this, together
with the tremendous range of facilities
offered with the operating system, means
that tailor-made software should be of a
very high standard. The latest release of
the operating systems, DOS SUPPORT
4.01, goes a long way to helping the new
user in handling the disk — most
commands, such as initialising the disk
and loading programs, now only require
one or two simple key depressions.

Because the 2040 is a IEEE device, it
can be controlled from machine code
using the IEEE protocol and plugs into
the IEEE connector on the back of the
PET. The PET to IEEE cable supplied by
Commodore is unusual in that it has an
ordinary edge connector at one end and a
male and female IEEE connector at the
other. This allows further devices to be
daisy-chained from the back of the disk
drive using the IEEE to IEEE connector
also supplied by Commodore.

If manufacturers of PET IEEE
peripherals and interfaces are sensible,
they will now design their units with an
IEEE socket to facilitate daisy-chaining.
There is no need to supply a separate
connecting cable as Commodore’s own
will do.

For those who wish to create, update
and make enquiries on random access
files; HIPPOSOFT offers a random-
access file handler for the 2040 drives on
the new business PETs. This handler
allows you to create up to 620 records on
one side of a diskette with each record
containing up to 40 variable length fields,
for example PART-NUMBER, UNIT-
COST etc.

PRIHT"CMSSEMREET CORRECT TIME EY SCREEN EDITIHG

peu PRD PT ae ae “ "SMIDSCTI#,°3,2)
= INPUT" Ml" : AF
TIS=LEFTSCAS, 2)+RIGHTS CAS, =)+"HO"
PRINT "02'S :POKES9468, 12° CG@=33388 * K=47S
26 R=11:FORTH=GTOS6QSTEF 3G : A=THen/ 198
A POKECOG+INTCK#RASINCAD +. 52-4Qe INTCRECOSCA D+. 5) 9,35 > NEXT

REM READ TINE

HR=VALCLEFT#(TI#, 2) spare eres 3,2)
ESEUBPERSRERDEDS

36 PRINT" J
HR=HR+MN/68
A A=HR#1."86 *R=7 : CH=42 GOSUB1G09
A ASMHen 38° R=9:CH=46 : GOSUB1 G08
AS=MNIDSECTIF. 5.19
IFMIDS¢TI¢,5, 1 2=AFTHENGZE
A A=HR#1,76 : R=?‘ CH=22: GUSUBINOS
66G A=MN¥n 7/30: R=9: CH=S2 : GUSUB1 E88
386 GOTO388
1606 REM SET HANDS
1H2@ C=COSCA):S=K¥SINCAD

{URE REB!" | HRS MH

1848 FORI=GTORSTEP. S:POKECOG+INTCI#S+.5)-4O8INTC1#C+.52>,CH NEXT RETURN

READY.

PRACTICAL COMPUTING January 1980

a as ogress 8 COT eT

Records can be added to the file,
amended, deleted or listed at random.
Any record within the file can be found
and displayed on the screen within two
seconds. Inquiries can be made on the file
by listing any individual record or by
searching the file for records that fulfil
certain requirements

Afraid of POKE?

For those who like me as beginners are
afraid of POKE commands on a PET,
here are two routines which may help to
show how versatile a machine it is, writes
J. Patterson from Leeds.

1 REM SQUARE PRINTING ROUTINE

5 PRINT ‘(CLR)”*

10 INPUT **HOW MANY UNITS LONG WOULD YOU
LIKE EACH SIDE TO BE"; N

15 IF N21 THEN PRINT **TOO BiG FOR SCREEN”:

FOR | = 1 TO. 1000; NEXT: GOTO 5
20M = 32892

25 PRINT "(CLR)"

30 FOR? = 1 TON

40M = M + 1: POKEM, 224
50 NEXT

60 FOR | = 1 TON

70M = M + 40: POKE M, 224
80 NEXT

90 FOR! = 1 TON

100M = M — 1: POKEM, 224
110 NEXT

120 FOR 1 = 1 TON

130M = M — 40: POKEM, 224

140 NEXT

150 PRINT ‘(CURSOR DOWN 22 TIMES)"

This routine uses a ‘space’ on ‘reverse’
field, but there are over 200 other symbols
which Pet will print.

Here is a short routine to demonstrate
them:

5 REM PET SYMBOLS

10M = 32767

20T = —I
30 FOR I = 1 TO 256

40M =M+1:T=T+1]
50 POKEM, T
60 NEXT

This will print all 256 symbols from the
keyboard in order. The board is printed
four times: first just as it stands, then
once more in the ‘shift’ position, then the
whole process is repeated with ‘reverse
field’ on. The number to POKE lies
between 0 and 255.0 is‘ ’ and 255 is ‘?’
shifted and in reverse field. Then comes
the tedious task of counting which
symbol you wish to use and then amend-
ing the square routine to accept it.

Insert a line 16 into the square routine
as follows:

16 INPUT ‘*WHAT SYMBOL WOULD YOU LIKE”’
tA

Type the number you would like and
alter lines 40, 70, 100 and 130 from POKE
M, 224 to POKEM, A.

As you can see, the results are not
squares but rectangles because the space
used by one character on the screen is 5
x 7 and not square; but then someone
may take this into account and write a
better program.

M is put at 32892 to put it far enough
away from the left hand upper corner of
the screen to look right. Lines 40, 50 and
60 print the upper line by adding 1 to M
for as many units as needed. In the same
way, lines 70 to 140 print the remainder
of the square. Line 150 pulls the cursor
down below the printout to allow easier
re-runs. Omit this line and the cursor ends
up in or near the square. O

METS Ly or

Convert to histograms

MARTIN EVANS, from East Finchley,
has sent in this snippet which he has used
to run programs to list file data on screen,
and to convert data into histogram form:

You noted in November’s Tandy
Forum that cassette data files are very
tedious and cause wear on the cassette
motor relay. One way round this problem
is not to use INPUT -—1 at all, but in-
stead to store the data in DATA state-
ments. If the data is only to be used in one
program, there’s no problem. It can easily
be altered and updated using the editing
facilities. But what if you want to use the
same bunch of data in more than one pro-
gram? :

One answer is to write a short program
consisting entirely of DATA statements,
eg:

5000 REM: MONTHLY CASES PROCESSED

5010 DATA "JANUARY", 1978 : REM: MONTH AND
YEAR OF FIRST DATA ITEM.

5020 DATA 10, 8, If, 12, 9, 15, 14, 13, 20, 14,

5030 DATA 16, 12, 8, 10,

5040 END

Then in writing any program to use this
data, be sure not to use any Line number
greater than 5000. Since DATA state-
ments work no matter where they are in a
program, it will not matter that the READ
statements are much earlier on. Now all
we need is a way of CLOADing a program
form tape and then CLOADING another
one without losing the first one. Fortun-
ately there is a way.

TRS 80 Computing Volume 1, no 3
gave a 3-line Basic program by Ron
Markel to do this. I’ve expanded this so as
to print the instructions for using it on the
screen. It looks like this:

1CLS

2 A= PEEK (16548)

3 B= PEEK (16549)

4E= 17129

5SmE:E= PEEK (S+!)* 256 + PEEK (s): IFE «
@GOTOS

6 POKE 16549, INT (S/256) : POKE 16548 S — INT
(S/256) * 256

7PRINT “INSTRUCTIONS”

SIPRINE

9 PRINT

10 PRINT ‘‘l. POSITION DATA TAPE”

1! PRINT ‘'2. SET RECORD TO PLAY”

12 PRINT “3. TYPECLOAD ENTER ”

13 PRINT ‘*4. AFTER DATA HAS LOADED, STOP

RECORDER AND REMOVE TAPE"

14 PRINT “5. TYPE POKE 16548, ‘‘;A;

15 PRINT ''6. TYPE POKE 16549, *’ ; B; ‘* ©

16PRINT ‘7. TYPE RUN 108 ENTER “

17 STOP

106 REM: START THE MAIN PROGRAM HERE

Each program for using the data should

begin with these lines. This is not as

‘cumbersome as it sounds. Just CLOAD
an existing program that incorporates
them and DELETE the rest of it.

The snags? If you accidentally return to
the beginning of the program, into the
append routine, you’ll have to type in the
POKEs again to get yourself out and back
into the main program. And remember
that the data lines must be numbered
higher than the main program. Even if
they are numbered lower, the program
will add them (out of numerical sequence)
on the end — and nothing you can do
with the edit facilities will get rid of them.

ENTER "
ENTER "

Save more time

CHRIS McGINNES has this to add to
Stephen Toop’s note in Tandy Form
(October), noting that not only is the key-
board disabled but also the program
running time is decreased:

This can be shown by running the
following two small programs below.

(i) 10 FOR = 1 TO 50000:NEXT
which takes approximately 108 seconds.

{ii) 10 POKE 16405,0:FOR 1 = 1 TO $0000:NEXT:POKE
16405,1
which takes approximately 93 seconds.

This is a saving of approximately 13 per
cent running time.

Tandy freebie

R.E. PEEL, wrote from Maidenhead to
suggest that the best way to get the Basic
debounce to work is to stroll down to the
nearest Tandy shop and ask for the key-
board debounce/real time clock cassette:
It’s free!

Also, with reference to Mr Sinclair’s
comments about pulling out the jack on
the cassette recorder to enable you to re-
wind, I would point out that since last
March, Tandy has been selling the TRS-80
with the CTR-80 cassette player, which
obviates the problem. I have had the full
volume CLOAD — on my CTR-80 the
volume needed is between 6 and 8 (8 being
the highest number in the CTR-80) but it
really does make life easier and is worth
the £10 or so it costs.

Has anyone come up with a method of
determining the file name on a tape to be
loaded by the SYSTEM command when
you don’t know what the name is?

Better way to jump

ED PHIPPS asks Tandy Forum,
November 1979, if there is a better way to
jump to the machine code than using the
USR function. M.P. Automation, Leeds,
tells us that there is:

On the Level 2 TRS-80 it is possible to
jump one way only to any location, using
the SYSTEM command. It is not neces-
sary to load a system tape. To jump to a
specified address, type in SYSTEM
(ENTER) / address (in decimal)
(ENTER).

So, referring to Mr Phipps’s Basic pro-
gram, delete line one, delete the remarks
about ignoring error messages, delete line
6. Enter or CLOAD the program, RUN it,
then type in ‘SSYSTEM (ENTER) /20425
(ENTER) NEW (ENTER)”’ and off you
go. Of course, as Mr Phipps says, you
must have answered‘‘MEMORY SIZE?”’
with 20425.

If you ever need to return to
““MEMORY SIZE?’’, do not switch off
— type in “SYSTEM (ENTER) /0
(ENTER).

Quicker key-checks

IN THE OCTOBER ‘Tandy Forum’ a
suggestion was made that the PEEK func-
tion could be used to scan the keyboard.
Alan Pearmain, from Mitcham, has done

a little experimenting, and found that only
seven locations need to be examined to get
a positive check for any key (except, of
course, SHIFT and BREAK). These loc-
ations are not unique; similar checks can
be made on other locations but it is only
necessary to be aware of those listed
below:

“ “se

SPACE 3
>>. No key returns at 4 in 14406
this could be the BREAK key

Tandy has published a software fix for
correcting the problem when using a
READ after an INPUT was executed.
The correction (POKE 16553,255 before
the first READ is performed) appears to
also do funny things to the logic in certain
IF ... RETURN ELSE ... statements
which worked correctly before the above
correction was used. Has anyone else
encountered this problem? The answer
was to split the line after the RETURN to
create a separate line.

PRACTICAL COMPUTING January 7980

aa eT oS ] a Se

Zzzz! Wake up,
Apple users!

THE LATEST market research re-
veals that over 40,000 microcom-
puters have been sold in the UK.
Apple/ITT and Commodore each
have about 20% of the market and
Tandy takes about 10%. Yet every
month about twice as many Tandy
and PET users write to their pages in
Practical Computing and pass on
their hints, tips and ideas.

Why are Apple users so different
from the others? Apple Pie is your
page, for you to write in with your
ideas for the benefit of other users.
Interesting applications are just as
important as programming tricks.

Instruction manuals

W. H. SKIPTON of ABEL Computer
Systems has sent us the following Apple-
soft subroutine which will print whatever
is currently displayed on the screen. He
thinks that it could be. used to print off
menu screens when preparing user
instruction manuals.

Notes

# is printed as £

The PRINT “PR... hasa <CTRL> D
embedded in it

The PRINT “‘80N....hasa <CTRL)> I
ie, they use Apple DOS and parallel
printer card

Improved file handling

J. E. VINE, Quality Control Engineer at
Samco-Strong, in Bristol, has been using a
32K Apple with dual floppy disk drives
and a printer. His company already has an
IBM 32 which is used for accounting
purposes on batch runs:

I am finding that the APPLE II could
be used as a production control aid, but I
would like to extract data from the IBM
32 and run it on the Apple. The most
convenient way of doing this would be for
the IBM 32 to output selected data onto a
floppy disc (8in) and then use the Apple to
read it.

Could you put me in touch with some-
one who would advise me on compat-
ibility? The 1BM 32 is programmed in
RPG and the disc sectoring etc will be a
problem to overcome by either hardware
or software.

In the same issue of Practical Com-
puting in the Review Section is the Disc
Comparisons article. Is there any
programming means by which the Apple
DOS can operate like the Tandy DOS in
that if a file is not found on Drive 1, it
automatically searches Drive 2? Is there
some way of using the ‘FILE NOT
FOUND” error message to transfer to
Drive 2? This would improve the file
handling capabilities of the system.

Also, I need to put on to disc files that
have a vastly varying number of records,
but the records are of fixed length. Is
there a convenient way of determining
how much spare capacity there is on a disc
prior to opening a new file? I have got
half-way through a file and then got a
‘disk full error’’, which is a bit annoying.

HHH RE KE RIE IE IEE HE IE IE HEHEHE EE HEHEHE HEHEHE HHH HHH HHH

C3 Lea,
*
#31000
* =
*#31005 FRINT
* FRINT
oO TO

SSNO00 TE ORS lae=

Pep
40 + J *
FRINT “*"s

#31020 FRINT

HHH KHKRKKKKRKHHHHKHE'
FRINT

+ PRINT :

*IJREM ABEL
*
*#INGHOMC, 1,0
*

*IRUN

REM PRINT CURRENT SCREEN
APFPLESOFT BASIC
IFLES Zale
HEHEHE HHH HHH HE
* HEH KHKHKEK KHER KHEREHEE"
Zit
Oo TO 1:
O TOpste:
(1024 + K * 128 + I *
296 + L))¢¢
NEXT K+J+I
HH HEHEHE HEHEHE HEHEHE

COMFUTER SYSTEMS

FRINT “80ON":

FOR J = 0 TO
PRINT “#"
FRINT CHRS

NEXT L:

PRINT
“PREO"

* ex 2 eK eK RK HK RK eK RK KK RK KK &

HH KK RKHKHE EHH HEE HEHEHE HEHEHE EHHREREKEREHHEEE

PRACTICAL COMPUTING January 1980

Installation error

WE HAVE discovered two errors in
Apple Intelligent Interface installation
and operating manuals and feel that for
the benefit of other Apple users the
following corrections should be made,
writes N. Hearne of Vlasak Electronics:

Apple serial interface card: The reset line
from the interface normally sits at a low
level and when reset_on the keyboard is
pressed, the reset line from the interface
goes high. This is wrong and results in
printer errors being thrown up. To rectify
this, swap the connections to pins 1 and 5
and IC2 (74LS109).

Apple communications interface card:
The modifications required to change the
baud rate of this card are shown on page
36 of this manual. If modified for
4800/1200 baud, as shown in the manual,
the computer will hang when instructed to
use the part in which the card is sited. This
is because IC2 (74C161) is not receiving a
Load enable signal. This may be remedied
by including a link between pins 15 on IC
1 and IC 2.

Current loop input

SOME OF you will find interesting the
recent experience of H. Carson and G.
Purdy with the current loop input of the.
Apple II high speed interface (A2L0008):

We have discovered that the input
speed of the device appears to be limited
by the 4N31 opto coupler to considerably
less than the speed capabilities of the
RS232 or current loop output. We tried
two different high speed interfaces. One
functioned up to 300 baud and the other
up to 1200 baud on the current loop input.

For normal working this would be quite
acceptable as current loop input is
intended for teletype-like devices which
generally operate at 110 baud. If,
however, it is necessary to use the current
loop input at higher baud rates, the opto
coupler can be replaced by a TIL 111 opto
coupler which will enable the device to
Operate at least at 2400 baud. The fact
that the opto coupler is mounted in a
plug-in base makes this change a two-
minute job.

We would like to add, however, that
this observation, which is really only of
benefit in specialised circumstances, in no
way detracts from the remarkable
versatility of the Apple II serial interface
card.

Minimal computers

There are now three minimal computers
available in this country. In order of
appearance, they are KIM, SYM and now
ACORN.

To assist readers to program these
machines, Arthur Richards has written a
Tiny Sym Assembler which we hope to
publish within the next few months.
Further patches for KIM and ACORN are
likely to follow.

Walter Wallenborn, secretary of the
6502 Users’ Club, has offered to help
us start a regular column about the
6502. Walter Wallenborn will write
part of the column in each issue, but
the rest is up to you, the reader. If
you wish to contact the 6502 Special,
send articles, ideas or problems
directly to us.

Cross-fertilisation

THE 6502 USERS’ Club was formed at

the beginning of this year by Steve Cole,

Harry Newman and myself (Walter

Wallenborn) because

@ We all had access to 6502 based

systems.

@ We came up with far more questions
than answers and

e@ We could find no-one who had col-
lected the answers.

So it was decided that the club would be
formed as a self-help organisation where
people at all levels of experience (and
inexperience) could contribute and learn.

Our objectives in the first place were to
@ Circulate a list of members’ names and

addresses and equipment to everyone

who joined the club so that there could
be as much .cross-fertilisation as
possible;

@ Provide an answering service to all
members’ direct questions with the
option of either referring that person
to another member or printing the
question in the Newsletter when I ran
dry;

@ Produce a regular Newsletter with as
much useful information as we could
pack in; and

@ Meet to further encourage discussion
and exchange of ideas.

We always welcome new members. The
more people we have, the better the club
can serve its purpose. If you are interested
in, joining, please write to me, Walter
Wallenborn, 21 Argyll Avenue, Luton,
Bedfordshire.

Interest in interrupts

THIS MAY help people interested in
interrupts. It was written on and for an
AIM 65, but the approach is generally
applicable. What it does is set the
Interrupt Enable Register to cause an
interrupt when timer | in the 6522 times
out. When the interrupt occurs, the B port

is checked to see if any input is low].

(indicating that a switch has shorted the
input to ground). All this is happening
transparently while the machine seems to
be doing everything else normally.

Weir br te Wo

anole

pas et) | VT stay

Wout”
Wa 4

PRACTICAL COMPUTING January 1980

(Pl a OO oT
Life forms unlimited

Life ought to be part of every computer buff's education. We
published a version for the TRS-80 back in August 1979,
which aroused so much interest that we are now publishing
another version, in Basic for the 380Z, by Steve Thomas.

THE GAME of Life was devised in 1970 by

Professor John Horton Conway, at the

University of Cambridge. The first account

appeared in Martin Gardner’s Mathematical

Games column in Scientific American

magazine in October 1970, and further items

appeared sporadically until January 1972.
Since then, probably more computer time

has been devoted to Life than to any other single
problem. Indeed, my own introduction to the
world of computing was through a desire to
implement Life on a computer. This article
gives a brief introduction to Life, and presents
an unusual algorithm, in the form of a Basic
program, for playing it on a computer.

Life was invented as a byproduct of
Conway’s attempts to develop a Turing
machine. It models the growth of colonies of
organisms. Three main considerations were
proposed in developing the ‘Laws of Nature’.
1. There should be no colony of organisms for

which there is a simple proof that it will

grow without limit.

2. There should be colonies which apparently
do grow without limit.

3. There should be many colonies which
develop and grow for prolonged periods
before dying off or becoming stagnant.
After much trial and error, the following

rules were developed:

1. Life is ‘played’ on an infinite plane divided
into (finite) square cells. Each cell can
hold one organism and is deemed to be
adjacent to eight other cells — four
diagonally and four orthogonally.

2. If an organism is adjacent to fewer than two
other organisms (ie fewer than two cells
adjacent to an occupied cell are occupied)
it dies from ‘loneliness’ or ‘isolation’.

3. If an organism is adjacent to four or more
other organisms, it dies from ‘overcrowd-
ing’.

4. If an unoccupied cell is adjacent to exactly
three organisms, a ‘birth’ takes place and
that cells becomes occupied. (Those who
consider a three-parent family unrealistic
should read The Gods Themselves by
Isaac Asimov.)

§. All births and deaths occur simultaneously,
so that dying parents can give birth, and
newborn organisms neither overcrowd the
generation in which they are born, nor
provide ‘company’ for isolated organisms.
At this point, a few examples would perhaps

be useful. Figure 1 shows the first few genera-

tions of the ‘T-tetromino’. Figure 2 shows the
blinker, the simplest of the class of colonies
known for obvious reasons as oscillators.

Generation 2 is identical to generation 0. Note

that, although this colony will persist indef-

initely, it does not conflict with consideration

(1) because the population remains finite.

Figure 3 shows the block, the simplest form of

‘still life’. There are about a dozen still-life

forms which appear frequently as parts of

larger colonies.

PRACTICAL COMPUTING January 1980

Figure 4 shows the glider, the simplest
colony which moves. The colony moves down
and to the right one cell every four generations.
There are several other species of moving
colonies known, notably the spaceship (Figure

There is of course much more to Life than
this brief account. Colonies have been dis-
covered which periodically throw off a glider.
These colonies, known as glider guns, grow
without limit, and thus conflict with consider-
ation (1). Similar in concept is the spaceship
factory, which periodically assembles and
launches a spaceship. Another interesting
colony is the ‘puffer train’, a colony which
moves leaving behind stationary ‘smoke’.
Examples of these and many other interesting
colonies are to be found in the Scientific
American articles mentioned above, and in a
recent issue of BYTE magazine (December
1978).

Implementation

There are at least two basic approaches
towards implementing Life on a computer. The
simpler approach is to approximate the infinite
plane of the playing area by a finite rectangular
array. Each element of the array holds codes

- for ‘alive’ or ‘dead’, with extra codes generated

while the colony is being scanned — ‘dying’
and ‘about to be born’.

This approach suffers from two major dis-
advantages. Firstly, the maximum size of the
colony (as measured by the area of the smallest
rectangle which will cover the whole colony) is
restricted to the memory space available. I have
not yet seen a published program which will
cope with the ‘R-pentomino’ (Figure 6). This
colony lasts for 1103 generations before
becoming stagnant, and eventually covers an
area about 500 by 550 cells.

The other major problem is one of execution
speed. The execution time such a program is
proportional to the area covered by the colony,
so that sparse colonies are dealt with very
slowly.

A more versatile approach, exemplified by
the program presented in this article, is to store
the coordinates of the living organisms. The
program is relatively complex, but the increase
in performance is enormous. The run time and
storage use are both approximately pro-
portional to the population, and the colony can
cover an area limited only by the precision of
the arithmetic used. This programme has an
arbitrary limit of one million square.

Running the program

When the program is started, it will prompt

Origin?

The program requires the coordinates of the
top left-hand corner of the colony. The colony
should be placed near the middle of the playing
area, as no check is made for overflow. After
the origin, a number of strings describing the
colony should be input.

Each string describes a single row of the
colony, with any character other than a space
signifying a live organism. Empty rows are
given by a string containing only spaces. The
input to the colony is terminated by a null
string. The program will then reprompt for an
origin. More organisms can be added if
desired, although they can only be added below
the old organisms. If an origin of 0,0 is given,
the program starts playing, and continues until
interrupted.

How it works

Each row of the colony which contains at
least one organism is described by a ‘row
number’ followed by a column number for
each organism on that row. The row numbers
are held as negative quantities and the column
numbers as positive. The whole colony is
described by a number of these row
descriptors, terminated by a zero.

The colony is scanned on a row-by-row basis
to produce the next generation. The old
generation is held at the high end of the storage
array, and the new generation at the low end.
At the end of the colony, the new generation is
shifted to the top of the array, displayed, and
the cycle repeated.

Three variables (R4, R3, and R5) point to the
row being scanned and the rows immediately
above and below it. If any of these rows do not
exist (ie they are empty), then the pointer is
zero. RI holds a pointer to the next existing
row after the row being scanned. This will be
the same as RS if RS is non-zero. RI is zero
only at the end of the colony. R holds the row
number of the row below the one being
scanned.

There are three column pointers, held in the
array C. C(1), C(2), and C(3) hold pointers to
the next existing column after the column
currently being scanned, in the rows pointed to
by R3, R4, and RS, respectively. If either the
rows or the columns do not exist, then the
column pointer is zero. C holds the column
number of the column immediately to the right
of the one being scanned.

DI, D2, and D3 hold the total numbers of
organisms in the three columns with column
numbers C-2, C-1, and C, in the three rows
under consideration. D4 holds the population
of the cell with coordinates R-1, C-1. The rule
for an organism existing in the next generation
thus reduces to

(D1 +D2+ D3 =3) OR (D1 + D2 +D3—D4 = 3)

The organisation of the program is straight-
forward. The subroutine at 1000 displays the
colony. Because the colony can be very wide,
the display is limited to a vertical slice of width
W2 through the colony. Where the display is
wider than the colony, the colony will be
positioned at the left of the screen. Other-
wise, it will be positioned according to the
variable W1 — if W1 =0 the window will be at
the left of the colony, and if Wl=1, at the

continued over

right. If there are four or more successive
-empty rows, then a message to that effect is
output instead of the blank lines.

The subroutine at 2000 produces the next
generation. It does this by repeatedly calling
subroutine 3000. This scans a single row of the
colony. Again, the main section of this routine
calls subroutine 5000 to check and if necessary
create each cell.

Subroutine 4000 is rather complex. Its
purpose is to determine whether the organism
in column C exists in the row specified by the
dummy variable Z. It does this by comparing
the column number of the column pointed to
by C(Z), if necessary incrementing C(Z) and
trying again. Subroutine 6000 calls 4000 three
times to determine the next value of D3, and
7000 shifts the colony from the bottom of the
array to the top.

Possible problems

The program is written in Research
Machines Ltd 9K Basic. The only features
which may cause difficulty with other Basics
are as follows:

Input of the colony is achieved by use of
strings. The actual method of obtaining sub-
strings will probably be different in other
Basics. The input is terminated by a null string.
If your Basic objects to this, replace line 140
with

IF QS = “ZZZZ" THEN 70
and terminate the input with ‘‘ZZZZ’’. Some
Basics may require that the string be
DIMensioned to reserve storage.

The program makes extensive use of ON .. .
GOTO statements. They have been arranged so
that control never ‘drops through’, so there
will be no problem about portability from this
consideration. However, some Basics do not
support the computed GOTO at all, and they
will have to be replaced by a series of IFs.

The program uses AND and OR within IF
statements. They can be replaced by multiple
IFs with some loss of efficiency.

The program assumes that 999999 and
1000000 are recognized as different and do not
cause overflow. If this is not the case, then the
size of the board will have to be reduced by
altering lines 40, 2010, and 3040.

The other possible source of trouble is that
use is made of the ability to use relational
expressions within arithmetic expressions.

10
20
30
40

50
60
70
80
90

100
110
120
130
140
150
160
170
180

190
200

210
220
230
240
250
260
270
280

290
300

310
320
330
340

Figure |

Figure 2

CLEAR 200

DIM A(3000) ,C(3)

W2=38

L=1E6 :REM The LHS of
the colony

P=]

R1=100

PRINT "Origin";

INPUT R,C

ON 1-(R=0)-(R<R1 OR

C<100) GOTO 100,70,260

IF C<L THEN L=C
INPUT Q$

R=R+1

RI1=R

IF Q$="" THEN 70
A(P)=1-R

P=P+1

FOR Z=1 TO LEN(Q$)

IF MINS$(Q$,Z,1l)="_"
THEN 230

A(P)=C+Z-1

IF A(P)>B THEN B=A(P)
:REM The RHS

P=P+1

Q=Q+1 :REM Population

NEXT Z

P=P+(A(P-1)<0)

GOTO110

A(P)=0

N2=P

GOSUB 7000 :REM Shift
the colony up
GOSUB 1000 :REM Display
GOSUB 2000 :REM Do one
generation
IF Q=0 THEN 340
T=T+l1
GOTO 290
PRINT "The colony is
extinct"

350 STOP

1000
1010
1020
1030
1040
1950
1060

P=G
IF B-L>W2 THEN 1040
C=-L
GOTO 1050
C=W1*W2-W1*B-(1-W1)*L
R=A(G)
PRINT "Gen"; T;

Novestnstin (He
PRINT =A(G); ","3 L;

a) Pop'';Q

1070

1080
1090
1100

GOTO 1100

P=P+l

ON SGN(A(P))+2 GOTO
1110,1240,1200

N1=R-A(P)

R=A(P)

N2=4

IF N1<4 THEN N2=N1

FOR Z=l1 TO N2

IF Z=3 AND Nl>=5 THEN

PRINT N1-3;''Rows"

NEXT Z

GOTO 1090

W=C+A(P)

IF W<O OR W>W2 THEN

1990

1110
1120
1130
1140
1150
1160

1170
1180
1190
1200
1210

1220
1230
1240
1250
1260

PRINT TAB(W);
GOTO 1090
PRINT

RETURN

at,
)

2000
2019 L=1E6
2020 B=

2030 N1=0
2040

PRACTICAL COMPUTING January 1980

2050
2060
2070
2080
2090
2100
2110
2120
2130
2140
2150
2160
2170
2180
2190
2200
2210

A(1)=0

A(2)=0

N2=1

IF Rl=O THEN 2200

R=-A(R1)

R3=0

R4=0

R5=R1

IF R5=0 THEN 2080

GOSUB 3000

IF R5<>0 THEN 2140

GOSUB 3000

IF R5<>0 THEN 2140

GOSUB 3000

GOTO 2130

A(N2)=0

IF B=0 AND N2>1 THEN
B=A(N2-1)

2220 GOTO 7000

5000 S=D1+D2+D3

5010 IF S<>3 AND S-D4<>3

THEN 5130 :REM Cell exists?

IF R+Nl=1 THEN 5100

A(N2)=1-R

N1=A(N2)

IF C-1<L THEN L=C-l

B1l=0

IF N2>1 THEN BL=A(N2-1)

IF Bl1>B THEN B=Bl

N2=N2+1

A(N2)=C-1

N2=N2+1

Q=Q+1

D1=D2

D2=D3

Z=2

GOSUB 4000

C=C+1

D4=D

D3=0

PRACTICAL COMPUTING January 1980

6010
6020
6030
6040
6050

7000
7010
7020
7030
7040

3000
3010
3020
3030

3040
3050
3060
3070

3080
3090
3100
3110
3120
3130
3140
3150
3160
3170
3180
3190
3200
3210
3220
3230
3240

FOR Z=1 TO 3
GOSUB 4000
D3=D3+D

NEXT Z
RETURN

FOR Z=0 TO N2-1
A(3000-Z)=A(N2-Z)
NEXT Z

G=3001-N2

RETURN

C(1)=R3+(R3=0)+1

C(2)=R4+(R4=0)+1

C(3)=R5+(R5=0)4+1

IF C(1)4+C(2)+C(3)=0
THEN 3200

C=1E6

FOR Z=1 TO 3

IF C(Z)=0 THEN 3080

IF A(C(Z))<C THEN

C=AKC (29),

NEXT Z

D1=0

D2=0

D4=0

GOSUB 6000

IF D3=0 THEN 3030

GOSUB 5000

IF D3<>0 THEN 3140

GOSUB 5000

IF D3<>0 THEN 3140

GOSUB 5000

GOTO 3130

R=R+1

R3=R4

R4=R5

IF R1=0O THEN 3280

ON SGN(A(R1)+R)+2 GOTO

R1=R1+1
ON SGN(A(R1))+2 GOTO
3240,3270, 3250

3250
3260

R1=0
R5=0
RETURN
R5=R1
RETURN

3270
3280
3290
3300
3310

4000
4010
4020

D=0

IF C(Z)=0 THEN RETURN

ON SGN(A(C(Z))-C)+2
GOTO 4030,4070,4080

C(Z)=C(Z)+1

IF A(C(Z))>0 THEN 4020

C(Z)=0

RETURN

D=1

RETURN

4030
4040
4050
4060
4070
4080

TRUE evaluates to —1 and FALSE to 0. Some
Basics allow this type of expression, but use
TRUE = 1, and some do not allow it at all.
The former case requires adjustment of a few
signs. In the latter case there is nothing for it
but to use a few more IFs.

Better things

The major difficulty with this program is
that it is very slow, at least on a microcom-
puter. Minor improvements can be made, by
optimising the code for speed, at some cost in
legibility. The only solution, apart from
acquiring a much faster computer, is to write
the program in assembly code,

Fortunately, translation is straightforward,
because most of the arithmetic consists of
incrementing by one. On an 8-bit machine, the
best board size is probably 32767 square.
Making it larger would slow the program and
increase its storage requirements, and 127
square is probably too small (although this is
still better than most programs). The effort
involved is well worthwhile, as Life really
comes into its Own when seen at several

3280, 3300, 3250 | generations per second.

A Guided Tour of
Computer
Programming in
Basic

by Thomas A Dwyer and
Michael § Kaufman; published
by Houghton Mifflin Co,

1977; 156 pages; $4.80.

DWYER and Kaufman wrote this |

as a teaching aid in 1973 and
adopted a very human approach
towards explaining programming
in Basic. The style of writing, the
cartoon-like pictures, large
lettering and imaginative but not
freaky layout make it an enter-
taining text to read. At the same
time it detracts in no way from an
explanation of the language.

The computer is presented as a
non-intelligent robot with the sole
function in life of obeying the
instructions given to it by a
programmer explicitly. The
authors clearly make the point that
humans are intelligent —
computers are not.

All this is under the heading
How to recognise a computer, and
for a change the authors start with
minicomputers and mention
punched cards only as an after-
thought. Large computers get a
look in as time-sharing terminals,
rather than as the fundamental
characteristic of computing.

The book starts-with an easy

introduction and then uses a
structured approach to build the
definition of the Basic language.
Each new statement type is intro-
duced and explained
meaningful examples, with flow-
charts used to illustrate the logic
behind the examples.

To illustrate the author’s easy
style, try this friendly exposition —
“the FOR and NEXT statements
were invented to simplify the
writing of programs that do the
same kind of thing over and over
again, in other words, programs
that contain loops. This means
that FOR and NEXT can help you
write short programs that produce
lots of output’’. It’s true, they can.

A concise explanation is offered
for the use of flowcharts and each
section ends with a good review of
the material introduced. The
examples are produced as Tele-
type listings and include the results
obtained from a computer run.

Exercises are included in each
section and although the authors
expect the reader to have access to
a computer to try them, the
majority are understandable as
read.

From time to time the Guided
Tour shows its age slightly by
talking about program preparation
using punched cards and paper
tape, neither of which are likely to
be of any but historical interest to
today’s reader.

More important, however, the

with,

authors point out a number of the
differences the reader is likely to
find in the implementation of the
Basic language, but they miss
others, including the range of line
numbers available for use and the
restrictions on dimensioning
arrays.

Our one major criticism is that
the authors have omitted to ex-
plain the use of character strings
and of files, both of which are
important parts of the current
commercial use of Basic. This
seems to be a common feature of
Basic books and presumably
results from their classroom
Origins.

It could be argued that children
learning the language will not need
an appreciation of text handling or
of files. We would disagree, of
course.

Conclusion

@ This book could do with an
update by the authors to include
some of the missing language
commands, especially those for file
handling. Apart from that, it
makes a very readable and enter-
taining introduction to the Basic
language, we can recommend it.

*We had to order our copy from the States,
which is why we give a dollar price. Ours was
from the Creative Computing catalogue and
despatch added $1.25 to the price. The address
is PO Box 789-M, Morristown, NJO7960,
USA. Please mention Practical Computing if
you order. Are there any U.K. stockists? Let
us know and we will print your address.

Personal Computing

Edited by Raymond P Capece,
published by McGraw-Hill,
1978; hard cover, 266 pages;
£11.20

THIS is yet another compilation of
previously-pu blished articles culled
from a variety of magazines with
dates between November, 1973
and November, 1978. It divides
into sections and is arranged with
the intention of providing an
introduction to hardware and
software for users of personal
computers. It’s a substantial and
generally well-produced book
from a major publisher and the
author is a respected U.S. technical
journalist. So far so good.

If you set out to obtain inform-
ation in the fast-changing world of
computing it’s important to get the
latest available. An article five
years old can be well out-of-date.
On the other hand, well-chosen
articles — preferably edited to
delete irrelevant references — and
arranged in a logical sequence can
provide a good grounding over a
wide area.

Some duplication is inevitable
between books such as this and the
things you might read in the
current magazines. Add to this the
fact that there will be references to
products — and even companies —
no longer around; and beware that
some items will have no relevance
to British readers — for example, a

professional printer-

"End user, quantity one, cash with order price.

100

PRACTICAL COMPUTING January 1980

list of suppliers of second-hand
equipment. You may find the use-
fulness of the content reduced
considerably.

That said, this a pleasant book
to handle. It has an index as well as
the obligatory list of buzzwords —
though both are short — a glossary
of terms and a useful list of
graphic symbols for electronics
diagrams.

For novices

It starts with an Introduction to
Personal Computing which has
some general information for
absolute novices and looks at a few
applications; not too bad. Part 2 is
Basic Computer Theory dealing
with architecture, chips and
memories; a trifle leaden, because
a sequence of magazine articles is
no way to educate someone in
textbook fundamentals. The third
part covers Advanced Theory and
goes further into the technology —
amuch better subject for magazine
articles.

Then there are eight reviews of
personal computers, much of
which looks rather like a public
relations exercise.

Part 5 deals with software and
includes an introduction to Basic,
an enthusiasm over Pascal, and a
discussion of the relative merits of
Pascal over Basic. In this section
each item can be regarded only as

the briefest of introductions.

The final part comprises speci-
fications and other information,
some of which isn’t very useful
here — unless you want to know
where you can buy a Teletype in
New Jersey.

Conclusion

@ As the title says, it’s basic, and
if you want plenty of basic inform-
ation, you’ll certainly get it. If you
have a good memory, you’ll be
able to astound your friends by
reciting the technical specifications
of 24 micros.

@ The bias is on hardware and
electronics, though, and though
this anthology might make a good
taster for the subject, you can
spend less and get more in the way
of an introduction. — R.G.

Getting acquainted
with microcomputers

by Lou Frenzel; published by
Howard W. Sams Co, 1978
(distributed through Prentice
Hall); paperback, 288 pages;
£6.55

LOU FRENZEL is an electronics
engineer by training and an
educator by profession. Currently
he runs that section of Heath Co
which puts out the H8 and H11

personal computers, as well as
Heath’s self-instruction kits and
other neo-educational products.
So he ought to know what he’s
talking about. And just to make
sure that he was not writing a
thinly disguised plug, we scoured
the text for references to Heath, its
microcomputers, and the idiosyn-

; cratic Benton Harbor bus that they

employ. We are able to report that
Heath Co gets only the exposure it
warrants.

The book promises it ‘‘will help
you learn more about micro-
computers and their application
and prove invaluable for those
who want to know more about
hobby and personal computing.’’

Basic knowledge

Our reaction is that the first
sentence is true; the second very
unlikely to be so. The book goes
into detail and requires at least a
basic knowledge of electronics
before you will be able fully to
understand it. Such quotes as ‘‘and
is usually Schottky TTL’’, with no
previous explanation of the mean-
ing of these words — nor for that
matter an index for them — makes
it pretty heavy going for the in-
experienced reader.

Another example: ‘‘The earliest
microprocessors used P channel
enhancement mode FETs. Some P
channel microprocessors are still

within your reach!

eae

being manufactured, but to date
most microprocessors used N
channel circuitry. Enhancement
mode MOSFETs are the prime
circuit elements, although some
depletion mode devices are also
used. CMOS integrated circujts are
also used to make microproces-
sors.’’ To a novice, this is obscure
and probably unnecessary.

It is not aimed at the rank
novice, though, and provides a
good introduction to microcom-
puters for someone who wishes to
expand his or her knowledge of the
subject. It offers a large amount of
useful information — for example,
describing several microprocessors
with their technical specs. It has
many illustrations, too.

The bibliography at the end is
very short and it seems somewhat
pointless — literature on micro-
computers is now extensive and to
give only two dozen or so titles
seems restrictive. The index in this
kind of book will usually be used
quite heavily: this one is fairly

superficial and should be
expanded.
Conclusion

For someone who has a reasonable
amount of background knowledge
of computer hardware, this book
will form an excellent introduction
to microcomputers. For other
people, it may prove too
technically detailed.

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102 PRACTICAL COMPUTING January 1980

ETS OO) Ss

There’s no need to tear your hair out getting to grips with
your monitor. R. D. Hodgson describes how to squeeze the

last drop out of the CPU while keeping hardware to a

minimumin...

A brief encounter with
monitor program software

FOR MOST microcomputer users, the
first software encountered is the program
that lives in ROM somewhere in the
system hardware. Even if the system costs
thousands, handles four floppies and has
colour graphics, it will almost certainly
also sport a monitor program.

The reason for this is built into the
processor chip itself, and is a result of
what happens during ‘reset’. With very
few exceptions, applying a reset pulse to
your microprocessor forces the program
counter to zero and more often than not
also disables the interrupt system. Once
the internal initialisation routine built into
the CPU chip is complete, the processor
fetches its next instruction from location
zero.

Obviously, if you have no program
living there, the CPU stands a good
chance of getting hopelessly lost in the few
few bytes, and we all know that feeling!

Depending upon what other com-
ponents are attached to the system buses,
the monitor program will probably output
a few bytes to initialise other programm-
able devices, such as PIOs and UARTs,
before doing anything else. On larger
systems, the monitor might also contain a
‘bootstrap’ routine which loads the
operating system down from disc if the
disc is ready; otherwise a simple monitor
is usually substituted.

Since micros of the 8080/Z80 type have
dedicated locations in the first few bytes
of their address space for use by restart
instructions and simple interrupts, it is
usual to jump round these locations and
leave those bytes for jumps to other useful
routines, of which more later.

If your system has a memory-mapped
VDU, the very next thing the monitor
program will do is clear the screen. This
usually takes only a few bytes of code

730
LD HL, VDURAM

LDC,CHARS
LD (HL),20H
INC HL

DECC

JR NZ,CLEARI
LD HL,BOTLFT

CLEAR]

LD (HL),CRSR
LD (POINTR),HL

PRACTICAL COMPUTING January 1980

MVIC,CHARS
MYVIM,20H
INXH

DCRC

JNZ CLEAR!
LX1H,BOTLFT

MVIM,CRSR
SHLD POINTR

Figure 2

Z30 8080
COMD LDA,(LENGTH) COMD
LDE,A
LD HL,TABLTOP

LD AHL)
cr

COMD2

JR Z.MATCH
LDA,L

ADD A,3
LDL,A

DECE

JR NZ,COMD2
JP ERROR

INC HL
LDE,(HL)

INC HL
LD DHL)
EX DE, HL
JP (HL)

since it involves writing a space (20H) to
each location of the VDU RAM. The
Nascom | monitor, NASBUG, has a clear
screen routine which can be called by the
user simply by putting the right charcter
into the accumulator and calling the
character output routine, and many
similar systems use the vertical tabulation
character for this purpose.

After clearing the screen, the cursor is
usually placed in the bottom lefthand
corner, as in Figure |.

The first visible part of the monitor
program is usually the monitor prompt,
which takes the form of a non-alpha-
numeric and is written to the first location
on the screen, or output to the console,
sometimes preceded by carriage return
and line feed — good practice, but, as
Nascom users will know to their annoy-
ance, not always implemented. The
memory-mapped VDU will then have the
cursor moved one space to the left and
cursor pointer incremented.

8080
LX!H, VDURAM ;Puts the address of the VDU

INHL

{Put the size of the screen inC
;Put a space in each location
3Go for the next location
;Count the locations

jTest for last location

;Put address of bottom left in
HL

;Put the cursor on the screen
;Put current cursor position in
pointer

LDA LENGTH ;Put the length of the table into
A

;Put it into E

;Put the table start address into
HL

;Read the first entry of the tabie
;Compare with the input
character

;Have we found a match

3If not, look at next entry
3(Jump round the address of the
;command)

;Last entry in table?

MOV E,A
LX! H,TABLTOP

MOV A,M
CMP C

JZMATCH
MOV A,L
ADI3
MOVL,A
DCRE

JNZ COMD2
JMP ERROR ;Not a valid command. Chastise
user

;Valid command

Fetch address of command
;toutine

tinto DE pair

INX H
MOV E,M

INX H
MOV D\M
XCHG

PCHL iJump to command routine

The appearance of the prompt
character indicates that the monitor is
sitting in a loop, reading the keyboard or
UART and waiting for input. This is how
the processor in most single-user machines
spends most of its time.

When an input is received it is de-
coded, either by look-up table, or by a
series of ‘Compare . . . Jump if Zero’
instructions. The choice depends on the
instruction set of the processor. The look-
up table can be part of the monitor ROM,
or may be written into RAM during
isation, or a compromise such as that used
in Nasbug may be used, where the look-up
table is in ROM, but the address of the
beginning of the table is written into RAM
during initialisation.

This means that other look-up tables
can be used, but that if all the original
commands are to be retained, the relevant
parts of the table must be duplicated in
the new table. Where the look-up table is
itself in RAM, further commands may be
implemented more simply. With the
‘Compare . . . Jump if Zero’ type of
command-decoding, as in the Intel 8080
monitor, no command extension is
possible.

The look-up table type of decoding
could be implemented as in Figure 2.

The appropriate command table would
then consist of groups of three bytes, the
first being the character used to call that
command, and the second two the address

Continued over

103

of the routine being called.

Decoding of input can be immediate, as
in the case of the Intel monitor, with
faulty commands indicated by some sort
of error character; or an input buffer can
be used which may allow editing of
commands (using backspace or rubout)
with decoding occurring on receipt of a
carriage return. The latter, without error
messages, is used on the Nascom, where
the video RAM doubles as the input
buffer.

Most monitors provide facilities to aid
the programmer in program entry and
debugging. The commonest are used to
examine and/or change registers or
memory, load memory locations from
some input device (where this device is a
cassette interface, a corresponding dump
facility is usually provided), execute a
program from a specified location, and
insertion of breakpoints. Some less
common facilities are single step and
block relocation (Move or Copy). Single
step requires the addition of hardware,
although some processors can handle a
single step facility entirely in the software.

It is common practice to make most of
the commands in the monitor into sub-
routines, which allows them to be called
by user programs: character input and
output are the most popular.

Breakpoint and single step facilities
almost always use the interrupt and restart
vectors near the beginning of the monitor
ROM. On the Z80/8080 family of pro-
cessors, several restart instructions are
provided which can be used for this
purpose.

An ‘insert breakpoint’ command can be
implemented quite simply by a routine
which replaces the specified byte with a
restart instruction, and stores the replaced
code elsewhere, as in Figure 3.

Normally, the next command would be
‘execute’, and when the restart instruction
is encountered, the program counter is
loaded with the restart vector (in this case
0038H).

Obviously, the above breakpoint
scheme is the bare minimum, and can be
abused. Repeated use of the breakpoint

command, without an execute command
between each, will leave your program full
of restart instructions, and only the last to
be set will be restored correctly.

This scheme could be expanded to allow
several breakpoints to be set if the
replaced instruction were stored with its
original address in tabular form, and the
return address on the stack used to restore
the correct byte of program.

Single step involves a similar recovery
routine, but does not need to save or
restore instructions. Nasbug uses the same
routine for both recoveries, but the
restoration of instructions is done by the
‘set breakpoint’ routine prior to setting
the next. At first glance, it may appear
possible to implement a single step facility
using inserted restarts, but since the
instruction length of all but the most rudi-
mentary controller-type micros is
variable, the program would need to
know the length of the next instruction
before it could work out where to place
the ‘restart’.

It is more usual, therefore, to
implement part of the single step routine
in hardware, and to use the interrupt
handling structure of the processor to
interrupt after one instruction has been
executed. Since the interrupts must be
enabled at least one instruction before the
jump to the instruction to be executed,
some sort of counter is needed to count
the number of instructions after the
‘enable interrupt’ instruction before
raising the interrupt request.

This is arranged so that the interrupt
occurs during the user’s instruction, but
since the processor always completes the
current instruction before acknowledging
an interrupt, this allows just one user
instruction to be executed. Unless the
processor has a non-maskable interrupt,
Or trap, it is necessary to ensure that no
attempt is made to step through a ‘disable
interrupts’ instruction.

An interrupt can either cause a jump to
a particular location near the beginning of
the monitor ROM, (as in the Z80 NMI, or
the 8085’s TRAP,RST 5.5,6.5 and 7.5
inputs) or may require a restart instruc-

Figure 3. ppt) LD HL(ADDRBK)BPT1 LHLD ADDRBK — ;Put address of break into HL
LD A,(HL) MOV A.M ;Pull out the code at that address
LD (BRKINS),A STA BRKINS ;Save the byte being replaced
LD (HL),OFFH MVI M,OFFH :Put restart code in its place
RET RET

0038H LD(HLSTO),HL SHLD HISTO ;Save H&L registers |
XCHG
LD (DESTO), DE SHLD DESTO iSave D&E registers
PUSH B
LD (BCSTO), BC POP H jSave BAC registers
SHLD BCSTO
PUSH AF PUSH PSW ;Save accumulator and flags
POP HL PPH
LD (AFSTO),HL SHLD AFSTO
POP HL POP H ;Save program counter where break
DEC HL DCX H yoccurred
LD (PCSTO),HL SHLD PCSTO
LD A,(BRKINS) LDA BRKINS Retrieve original instruction
LD(HL),A MOVM,A ;PUt it back
LD HL,O LX1 H,°
ADD HL,SP DAD SP ;Save user's stack pointer
LD SP,MONSTK LXISP,MONSTK ;Reload monitor stack pointer
JP INPUT IMP INPUT Go for next command

104

tion or other vector to be supplied by the
interrupting hardware, as with the 8080.

The ‘execute’ or ‘go’ command usually
takes the form of a carefully prepared |
return from a non-existent subroutine,
and can frequently be used either with or
without a start address. Some monitors
such as MIKBUG require the user to
insert the start address into a RAM
location before the use of this command.

Since most monitors save the main
registers, it is usual to restore all the saved
registers before the ‘return’ instruction,
although one processor, the 9900, renders
this unnecessary because of its workspace
pointer, which effectively places the
registers in RAM, and they can then be
saved just by changing the workspace
pointer.

The ‘execute’ command for a Z80-
based or 8080-based system might go like
this:

Z30 8080
(DHL A(SPSTO) LHLDSPSTO Restore user stack
pointer
EX SP,HL SPHL
LDHL(PCSTO) LHLD PCSTO :Put program counter
on stack
PUSH HL PUSH H
LD DEDESTO) LHI.D DESTO Restore D&E registers
XCHG
LD BC\(BCSTO) LHLD BCSTO ;Rstore B&C registers
PUSH H
POPB
[DHE AAFSTO) LHI DAFSTO ;Restore accumulator
and flags
PUSH HI PUSH H
POP AF POP PSW
LDHL.HI STO) LHL D HISTO :Rstore H&L. registers
RET RET :Jump to address

trom PCSTO

A listing of the monitor program for
your system may at first appear to
comprise a lot of short routines and a lot
of call instructions, since many functions
are duplicated in each command, such as
acquisition of arguments, checking for
valid digits and delimiters, echoing input
back to the console, control of the cursor
and scrolling (on memory-mapped
VDU's), conversion between ASCII and
hexadecimal, and many others.

Some single-board computers with
built-in keypads and displays make much
greater use of the monitor program, using
it to scan and decode the keys,
debouncing, decoding and driving LED
displays. Some SC/MP based micros,
where a test pin is used on the processor,
even accept a serial input directly, and
bytewise reconstruction of the serial data
is done by the monitor.

The main disadvantages with this tykpe
of monitor program is that when the CPU
is away doing something else, the display
and keyboard die, and if the display is to
be used to output messages by the user’s
program, he is often faced with having to
duplicate some of the scanning routines
into his software, is making sure that the
display is refreshed often enough one of
the hardest tasks.

I hope that this will have been some
help to those of you who are struggling to
get to grips with your monitor, it is by no
means exhaustive. There are many
variations in use around the micro world.

PRACTICAL COMPUTING January 7980

fa .. eee (

Cut out conversion fiddle
with assembler program

SOONER OR LATER the majority
of micro-computer users will want to
write programs in machine code. The
usual reason is that high-level
language interpreters like Basic are
far too slow for some applications.
Examples of such applications are
sorts, and interfacing with external
equipment in data logging or process
control. Using machine code can
often increase speed of processing by
as much as 200 times the speed of a
comparable Basic program.

Machine code programs can be written by,
hand, but this is a slow and very tedious.
operation and the result is invariably full of
errors. Hand coding involves the conversion of
the microprocessor instructions into a set of
binary values for storage in memory. It is much
simpler to use a program to perform this
function. Such a program is known as an
assembler. It allows a machine code program
to be written in an assembly language rather
than the binary values used in hand coding.

An assembly language uses a set of
mnemonics and symbols to repreent the
program. These are then translated by the
assembler to produce the actual binary values
of the machine code program. In comparison
with a high-level interpreter of compiler, each

6502 instruction set opcode mnemonics
ADC — add with carry to accumulator
AND — “AND” memory with accumulator
ASL — shift accumulator left one bit
BCC — branch on carry clear
BCS — branch on carry set
BEQ . - +... branch on zero result
BIT — test bits in memory with accumulator
BMI — branch on result minus
BNE — branch on result not zero
BPL — branch on result plus
BRK — force an interrupt or break
BYC — branch on overflow clear
CLC — clear carry flas
CLD — clear decimal mode
CLI — clear interrupt disable bit
CLV — clear overflow flas
CMP — compared memory and accumulator
CPX — compared memory and index X
CPY —compared memory and index Y
DEC — decrement memory by one
DEX — decrement index X by one
DEY — decrement index ¥ by one
EOR — exclusive ‘OR memory with accumulator
INC — increment memory by one
INX increment index X by one
INY — increment index Y by one
IMP — jump to new location
JSR — jump to subroutine address
LDA — transfer memory to accumulator
LDX — transfer memory to index X
LDY — transfer memory to index Y
LSR —~ shift accumulator one bit nght
NOP ~- no operation
ORA — /‘OR* memory with accumulator
PHA — push accumulator on stack
PHP — push processor status on stack
PLA — pull accumulator from stack
PLP — pull processor status from stack
ROL — rotate accumulator one bit left
ROR — rotate accumulator one bit right
RTI — return from interrupt
RTS —return from subroutine
SBC ~- subtract memory and carry from accumulator
SED — set decimal mode
SE! — set interrupt disable status
STA — store accumulator in memory
STX — store index X in memory
STY — store index Y in memory
TAX — transfer accumulator to index X
TAY — transfer accumulator to index Y
TSX — transfer stack to index X
TXA ~ transfer index X to accumulator
TXS — transfer index X to ssack
TYA — transfer index Y 10 accumulator

PRACTICAL COMPUTING January 1980

assembly language statement will translate into
one machine instruction occupying between
one and three bytes of memory. A high-level
language statement will, however, be trans-
lated into a whole block of machine instruc-
tions. It is for this reason that a machine code
program is often so much faster than a high-
level program, since a single assembly
statement is often equivalent in its function toa
high-level statement.

All digital computers use the binary number
system for representation of data and in-
structions since a computer understands only
ones and zeros corresponding to the ‘‘on’’ and
“off” state. Such a system is, however, very
difficult for human users and it is more
convenient to use number representations like
octal (base 8), decimal (base 10), or
hexadecimal (base 16). To compare binary
notation with hexadecimal — the usual
notation used in assembly languages for eight
bit micros — the following of an instruction to
load the accumulator of a 6502 micro with the
value 95 (decimal).

A hand-assembled machine code program
would most likely be written in hexadecimal,
and a monitor program used to load it into
memory and convert it into binary format. The
numeric representation of instructions is,
however, tedious to work with and for this
reason an assembly language uses a symbolic
representation for the instructions.

Thus in the previous example the instruction
might bé written as:

LDA # 95
where LDA is a mnemonic symbol for the
instruction to load the accumulator, this is
equivalent to the hexadecimal value AQ in the
previous example. The value which is to be
loaded into the accumulator is represented in
decimal form and the # sign is used to show
that an immediate addressing mode is used.

A program written in this symbolic form is
referred to as the source code. This is converted
by the assembler into a numeric form which is
known as the object code. The processor
cannot execute a program in source code form
— it must first be converted into object code by
being assembled. In assembly language every
instruction in a program has a symbolic name
— ie LDA — referred to as the opcode (short
for operation code). Thus in the 6502 assembly
language there are 55 different opcodes: see
figure 1.

An assembly language instruction thus
consists of an opcode and perhaps also an
operand which specifies the data on which the
operation is to be performed. This operand
may be a value in either decimal, hexadecimal
or octal format, or a symbolic name, which
references a location in which the data is
stored.

In the 6502, instructions have a maximum of
one operand, though some of the so-called
implied instructions, of which there are 25,
have no operand. An example of such an
instruction is CLC — clear carry bit. Some
instructions perform jumps or goto functions,

thus instructions may be labelled for reference
by other instructions. In the following example
the label START is used to reference the first
instruction by the conditional jump instruction:

START

LDA # INPUT

CMP # 95

BEQ START

Programming in assembly language is much

Figure 2

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LSTKEV=$37

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3G #=BEGIN

REPEAT KE ENABLE

REFON SEI

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STA IRRY

LIAR #2 3REFEAT
STA IFRMY+1
LIA #1

STR REPDEL
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=
it

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Zan:

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314 BEG REF I

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1446 LIAR ##64

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14656 LOA ##42

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1496 EHD

REAL.

105

more difficult than programming in Basic,
since not only does it require the learning of an
extensive set of opcodes, it also requires very
Strict adherence to assembly language
structure, addressing conventions and
processor status.

It is very important that assembler instruc-
tions are formatted correctly. To achieve this,
source code programs are usually written using
an editor program. The function of an editor,
as its name suggests, is to allow the program to
be modified easily. It also incorporates such
functions as auto line numbering, searching for
variable names, changing variable names and
printout formatting for ease of reading.

Correct format
The source code will contain not only
machine instructions but also assembler
directives which are required by the assembler
program, for example to determine the starting
address of the object code. Each machine
instruction can consist of up to five fields, each

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ERRORS = G68

106

field separated by one or more spaces. Two of
the fields, the line number and the opcode,
must always be present in every instruction: the
remaining fields depend on the instruction and
the program. The instruction format is:

Line number Label 1 Opcode Operand: Comment

An example of a source code listing for a
6502 program is shown in figure 2. This was
produced by the editor on Commodore’s new
assembler package for the PET. The source
code program, which was written to provide
the PET with a repeat key function, can be
divided into two parts.

In the first part the variable names used in
the program to represent data storage locations
are assigned addresses (these are in
hexadecimal, this being signified by the
preceding $ sign). This section of the code ends
with the assembler directive ‘** = BEGIN”
where ‘“‘BEGIN”’ has been assigned a value of
hexadecimal] 1000, which is to be the starting
address of the program.

i®. REPEAT KEY

5%) 866°10773

1 RRR ERE EERE R RRR ER RRR

REF UEL=$08

DELAY = =F@1

KE’ =$02

IRGY =$96

LSTKET=$97

BLINK =$AS

BEGIN =$160G@
¥=BEGIN

iREPEAT KE% ENABLE

REFON SEI
LDA
STA
LIA
STA
LIA
STA
Gey
RTS

[REPEAT KEY FUNCTION

#<REPERT
Ire’
#>REPEAT
IRQV+1

#1
REPDEL

REFEAT LIA
CHP
BEQ
STR
LDA
STA
JF
CHP
BEG
LIAR
BEQ
DEC
BNE
DEC
BHE
LIA
STA
LDR
STA
BME
END

LSTKEY
KEY
REF 1
KE"
#414
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IRQY
#3FF
REPEND
DELAY
REP2
DELAY
REPEND
REFDEL
REFEHD
#464
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BLINE
REFEND

REPEND
REF 1

The second section of the code consists of
the actual machine instructions, each being
written according to the above format.
Comment headings between subroutines and at
the beginning of the program are defined by
being preceded by a ‘‘;’’ and comments after
an instruction are defined by being preceded by
a ‘‘:’’, The source code program ends with the
assembler directive to end ‘*.END’’.

Having written a program in object code and
saved it on either tape or disc — further
functions provided by the editor — it is ready
to be assembled. The assembler loads the
object code file off the storage media and
procedes to do the first pass assembly. Two
Passes are required to assemble a program. In
the first pass, all the opcodes and all the
operands except jump addresses are calculated
and placed in the correct memory locations.

In the second pass, the jump addresses are
calculated and inserted into the unfilled
memory locations left for them in the first
pass. These memory locations are entries in the
source code listing created by the assembler
and not direct entries into memory locations.
Any errors in the object code encountered by
the assembler are. displayed during the
assembly process together with the appropriate
error message.

If errors are present in the object code, then
Obviously the object code will have to be
corrected before a correctly assembled source
code is produced. The source code created by
the assembler program is stored on disk or
tape. Having stored the source code listing, the
assembler will if reqired produce a printout, as
in figure 3, of the complete source code,
together with a symbol table, giving the
location of all labels and data names.

Once created, the source code file on
magnetic media can be used by a third program
in the assembler package — the loader. This
program, as its name suggests, converts the
hexadecimal numeric values created by the
assembler in the source code program into
binary values stored in the correct locations in
memory. Once the program is loaded, it can be
run in the normal manner using say the SYS
command from Basic.

There are many different kinds of assembler
available on the market, covering every make
of microprocessor. The majority of full
assemblers follow the general pattern described
above and of which the Commodore assembler
is an excellent example.

There are, however, other simpler
assemblers available, some even writen in Basic
and consequently extremely slow. A very useful
type of simple assembler is known as a spot
assembler. This does not require an editor or
loader, being just an expanded monitor. A spot
assembler does not allow the use of variable
data names or labels but simply converts
opcode mnemonics directly into binary values
and inserts them into the correct memory
locations.

Spot assemblers are very handy in construct-
ing small machine-code programs or system
Patches, since they give one an almost
interpreter-like control of the program,
especially when used in conjunction with a
disassembler. An example of a spot assembler
is found in Commodore’s new Extramon 7.5
monitor program for the PET — this also
includes a disassembler and a host of other
useful functions.

@ The Commodore assembier is available from
any Commodore dealer, price £75 on diskette
for 16 or 32K machines with Commodore disk
drive and printer.

PRACTICAL COMPUTING January 1980

Outside
connections

Nick Hampshire deals with the daunting
topic of interfacing a micro to the outside
world by discussing the basics of the
KIM’s I/O port.

THE CONNECTION of a computer to
external electronic and mechanical devices
can open a new world of applications, yet
it is an area which most people approach
with considerable trepidation. Such fears
are, as will be shown in the short series of
articles of which this is the first, unfound-
ed and due mainly to the fact that most
computer programmers are not electronic
engineers and vice versa.

The computer system on which I shall
base this introduction is the KIM 1, the
reason being that it is an extensive, easy-
to-use and, above all, has the same 6502
microprocessor as Pet and Apple com-
puters.

The Kim, like most microcomputer
systems, has a programmable eight-bit
1/O port, and it is the connection of de-
vices to the lines of this port and their
} control by a computer program which we
will examine.

Those lines of the I/O port are usually
from a device known as a PIA or Periph-
eral Interface Adapter. The most common
are the 6520 and the identical 6820. The
PIA is under direct control of the pro-
cessor and consists of a set of eight-bit
registers, each of which functions, as far
as the processor is concerned, as a
memory location.

Of the registers on a PIA, two types
which are important and their function
must be understood if we are to connect
external devices to the I/O lines, and
control those devices by means of a com-
puter program.

The two registers which are universal to
every PIA are the Peripheral Interface
Buffer and the Data Direction Register.
The Peripheral Interface Buffer — as its
name suggests, is the register — memory
location — from which data being put out
to the [/O lines is stored, and from which
data coming-in on the I/O lines is read by
the processor.

The Data Direction Register is used to
define each of the eight I/O lines as being
either an input or an output. It is this
ability of a PIA to have the direction of
data on each line controlled by a program,
which is one of the most powerful features
of these devices.

On the Kim, the Data Direction Regis-
ter for I/O port A is at memory location
1701, and the Peripheral Interface Buffer
is at location 1700. If we want to define
I/O line S as an output, we must set bit 5
of location 1701 to a logical ‘1’. Similarly,
if we want to output on line 2, we must set
bit 2 to ‘1’ and so on. If we want to define
an I/O line as an input, we must set the

PRACTICAL COMPUTING January 1980

ees Computabits mmm

corresponding bit of the Data Direction
Register to logical ‘0’.

Having defined the function of each
I/O line as either an input or an output,
we can read the current state of those lines
configured as inputs by examining the bits
corresponding to those lines in location
1700, the Peripheral Interface Buffer.
Similarly, we can output data on those
lines defined as outputs, by writing the
desired output to the corresponding bits
of the Peripheral Interface Buffer; logical
‘1’ for a 5-volt output on that line and
logical ‘0’ for a zero volt output.

As an example, say we have defined line
5 as an output and line 3 as an input. If we
want to set line 5 to give a 5-volt output,
we must write a binary word ’x xxx 1x xx’
to location 1700 — the x’s represent bits
which can be either ‘1’s or ‘0’s.

To read the current state of line 3, we
must read location 1700 and look at the
state of bit 3, thus if it is ‘x x 1 x x x x x’,
line 3 is currently in a high or 5 volt state,
and if ‘xx0xxx xx’, the line 3 is in a low
or zero volt state.

The simplest form of output circuit is to
use the computer to turn a device, such as
a lamp or a relay off or on.

More sophisticated outputs require two
or more I/O lines to control a device. The
computer would not turn the device on or
off; it would also control its mode of
operation. Whatever the sophistication of
the computer control, it relies on the
ability to control individual I/O lines with
a computer program.

The best way of learning to do that is to
construct a simple experimental 1/O
circuit. Mine uses a single eight-bit I/O
port and provides four outputs to light-
emitting diodes and four inputs from
single-pole, double-throw switches. A
single 7404 integrated circuit provides the
four buffers on the outputs, which are re-
quired to raise the power output from the
PIA to that required to drive the LEDs. It
should be noted, however, that ‘those
buffers invert the output of the PIA, so a
zero voltage output from the PIA will
light on a piece of Veroboard. The num-
bers by the side of each buffer on the
circuit diagram indicate the integrated cir-
cuit pin number (pin 1 on an IC is to the
left of the notch at one end of the IC
looking from above. The other pins are
numbered anti-clockwise. The circuit re-
quires 5 volts of power, which can usually
be obtained from the computer power
supply — see manufacturer’s document-
ation — or from a battery. Pin 7 of the IC
should be connected to ground and pin 14
to + 5 volts.

Having constructed the experimental
1/O circuit, it should be connected to the
processor I/O port via the appropriate
connector, and its power supply turned
on. With the Kim, and most other com-
puter systems, we can use the monitor
to control the operation of the PIA from
the keyboard. We must first set the Data
Direction Register so that lines PAO to

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® Circle No. 189

108

PA3 are configured as outputs. This
means that we must set bits 0 to 3 of
location 1701 to logical ‘1’ and the re-
maining bits to zero. To do this, we load
1701 with hexadecimal ‘OF.

Remember that the lines on our circuit
have been inverted so that to light a LED
on a particular line we must write a ‘0’ to
the corresponding bit in the Peripheral In-
terface Buffer. Thus to turn-on the LED
on line 0 we must set bit 0 to ‘0’ and bits
1,2 and 3 to ‘1’ in location 1700; since bits
4 to 7 have been defined as inputs their
contents will reflect the current state of
the input lines.

To do this we need to write hex ‘OE’ to
location 1700, whereupon LED 0 should
light and the other three LEDs should go
out, providing that the circuit was
assembled correctly. To turn-on LED 1
write hex ‘OD’ into 1700; LED 2 is ‘OB’
and LED 3 is ‘07’; other values give com-
binations of two or more LEDs on and
‘OF’ extinguishes all four.

Having controlled the outputs man-
ually, it is simple to control them via a
computer program. The computer
program must perform the same sequence
of processes which were performed in the
manual output of data, therefore, to turn-
on the LED on line 2 we can use the
following short machine code program:

A9OF LDAWOF
8DO!I7TSTA 1701
ed ag Output a ‘0’ on line 2

8DO0017STA 1700

@ ~~ RTS End

By varying the values, this little sub-
routine could be used in a program to turn
any single or combination of LEDs on or
off. By stringing together a sequence of
program steps like this one, where each
stores a different value in location 1700,
we could create a sequence of flashing
lights. This would require four blocks of
code, as indicated, and would terminate in
a jump command to return the program
to the beginning, to start the sequence all
over again.

If you try this, however, all you will see
is four lit-up LEDs since the program runs
so fast that we are unable to perceive what
is happening. To see the flashes we must
slow the program by inserting a delay be-
tween each step. A delay can be generated
by using a counted loop, like a FOR —
NEXT loop in Basic.

Since machine code programs are so
fast it is usually necessary to nest two or
three loops, one within the other, to
obtain a visually-acceptable delay of one
or two seconds. The following is a simple
location hex 0 as variable storage:

Set Data Direction Register

200 A2FO LODX LDX#FO sinitialise index

register X
AOFO LODY LDY#FO sinitialise index
register Y
ces LOOPY INC Y sincrement Y
C000 CMP Y00 tisY = 0?
DO FB BNE LOOPY :ifsogoto LOOPY
Es INCX tincrement X
£0 00 CMP X¥h00sisX = 0?
DO F4 BNE LODY tif so go to LODY
£600 INC Z00 sincrement location 0
AS 00 LDA Z00
900 CMP#00 tislocation 0 = 0?

DOEA BNELODX — : ifso goto LODX
60 RTS :return to calling
program

The delay generated by this program
can be varied by changing the initialis-
ation values for index registers X and Y.
The smaller the values the longer the delay
— the values indicated give a delay of
about one second. This delay subroutine
can be incorporated into the flashing
sequence of LEDs program so that each
LED remains lit for about one second
before being extinguished and the next
LED lit. That is done by this program,
starting at location 10.

10A9OF LDA*OF sinitialise Data Direction Register
8D0117 STA1701

15 AIOE LDAOE :set LED 0 on others off
8D0017 STA 1700
200002 JSRDELAY — :go todelay subroutine
A90D LDA OD sset LED } on others off
8D0017 STA 1700
200002 JSR DELAY
A90B LDAOB :set LED 2 on others off
8D0017 STA 1700
200002 JSR DELAY
A907 LDAA07 set LED 3 on others off
8D0017 STA 1700
200002 JSR DELAY
4C 1500 JMPOOIS ireturn to start of display program

By changing the binary values loaded
into the Peripheral Interface Buffer the
sequence or pattern of flashing LEDs can
be changed. Further steps in the sequence
can be added by inserting further display
blocks of code. For long sequences,
however, this method takes an excessive
amount of memory and in such cases it is
best to use a table of output values.

Sequential

In the following program each value to
be loaded into the Peripheral Interface
Buffer is stored in the sequence in which it
is to be output, in one of the bottom
256 memory locations. The program
accesses this table from location | up-
wards, sequentially, and on reaching the
entry in location 255 returns automatically
to the entry in location 1. The contents of
the table can be input manually using the
monitor and the keyboard.

0240 A9 OF INIT LDA4OF sinitialise Data
Direction Register
8D Ol 17 STA 1701
0245 A201 DISPLAY LDX4Q01_—:set index register X

to point to start of data
table

sfetch entry from table
pointed to by X index
register

0247 BD0000 DISP2 LDA 0000,*

8D0017 STA 1700 output to Peripheral
Interface Buffer

BA TXA stransfer X reg to
accumulator

48 PHA tput accumulator
on stack

20 00 02 JSR DELAY

68 PLA :pull accumulator
from stack

AA TAX transfer accumulator
to index X

E8 INX rmove X register
pointer to next entry

E000 CPX 00 rend of table?

DO EE BNE DISP2

4C 45 02 JMP DISPLAY

The reason the contents of the index
register are transferred to the stack is that
the X register is used in the delay sub-
routine, and if the index register were not
saved the table pointer would be lost.
Having generated a delay, the contents of
the index register are recovered from the
stack. @

PRACTICAL COMPUTING January 1980

Mn as CONpUtAbItSs ae Shop Window

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Numbers all change |) "~~

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The program listed below not only does | 360 N is converted into a numerical digit. Also other $100 products.
this conversion quickly for all numbers, | 340 Q is the remainder of the number. ‘ :
but it also works for number bases from 2 | 380 This is a ‘fudge factor’ which slightly ve mec ttcirect from U.S.A. and our
< . ° 5 ification as necessary.
(binary) through 10 (decimal) and 16 increases Q. I have found that it works ; 3
(hexa-decimal) to 36 (using the numerical for all numbers and bases I have tried, ecu support. Write or call for
digits, and all the upper-case alphabetical but micros other than the Sorcerer may Sarit
characters). It can even be extended require a different factor. It is necessary INTELLIGENT ARTEFACTS
through the ASCII characters 91 to 96 to because of the division in line 330. geeecsse Road,
the lower-case alphabetical characters. Take care that you input the right kind Royston, Herts.
For those uncertain about what number | of characters for the number base you Tel: Arrington 689
bases are, an explanation of them is given | start with, and that L2 is sufficiently large -
later. for the answer, otherwise nonsense * Circle No. 190
The program has a further use. | answers will be displayed. NEW NEW
Changing a number from one base to | The decimal number 234 TRS-80 EXTENDED BASIC
another can be a way of packing more in- | which we read as two hundred, thirty and | | (2reue, Go0 ane grea, onan
formation into an array. For example, | four may be written as (with variables), DEFUSR, LINE INPUT, LINE
suppose you want to record the results of 200+ 30 + 4 a = e Lieairg ae ae and DEFFN.
football matches between teams A and B } or as 2+100+3x10 +4x!I LEVEL IIGAMES PACKS £12 each + 50p.
over the years in one element of the array | or as 2x10? + 3x10! + 4x 10° postage. ...
FOOT(A,B). There could be no inform-| 10% is read as ten to the power of two, || PACK 1omato Amer (own oaehi
ation (0), a home win (1), an away win (2), | and means that the number 10 is multi- (animated quick draw game), Simon (with

or a draw (3). plied by itself 2 times (10 10). The 10 is PACK 2 Stertrok (real time graphic version)

Thus for a series of results over the | said to be the base of the system (hence fudirigiata (over G00 words), Golt, Tle-nec- toe!
years, we might have a sequence such as | the name decimal). PASSWORD CRACKER!
2122110. 1f we consider this as a number Note that any base raised to the power Disk command program enables retrieval of
to base 4 (since four digits are used), we | of zero is equal to one. Notice that the 1 tah Ta tea) Bre ee:
can convert it into its decimal equivalent | power for the right-most digit (the four) is CHEAP HARD COPY!!!
9876, and so save space. 0, that for the next digit to the left (the Still a small number of Olivetti teletypes

The remark statements in the program | three) is 1, and the next 2, and so on. Saas ge Sie -_
give an indication of how the program is| _ In the hexa-decimal system, there are 16 | | 50nd to: dake Gammander. 305
organised, but an explanation of the | symbols, consisting of the ten digits0to9| | Birmingham B34 7EA.

following lines of the program may be | plus the six upper-case letters A to F. A Tel: (021) 747 6964

helpful to an understanding of it: hexa-decimal number such as 2A3F may ¢ Circle No. 191
010 Sorcerer’s method for clearing the | be converted to its decimal number equiv-
screen, alent by first converting the individual THE BEST OF
130 Asks for the number of digits or | characters to their decimal equivalent AMERICAN SOFTWARE
characters required in the answer. (from A=10 to F=15), and then multi- | | iy -ounts payable SSG
240 Divides the number into its separate | plying each of these by the base 16 raised Accounts receivable SSG
digits or characters. to the power appropriate to the position General ledger SSG
260 Converts an alphabetical character in- | of the digit or character in the original oo zee
to its numerical value. hexa-decimal number. Hence 2A3F Basic 2
270 Converts a numerical digit into its] becoMeS 4,464 10x16: +3 x 16! + 15 x 16° Letteright
numerical value. = 2x16%16K16 + 10x 16x16+3x 16 +151 ___ Whatsit ;
280 The numerical value is multiplied by| = 515" Jae Vicar 8 seis So elie
the base B1 raised to the power (L2-R) = 1081S Q
; SWC ELECTRONIC DISTRIBUTORS,
Fig 1 Port locations vale Suk : - —— eat 8 ' P.O. BOX 30 LONDON E4
56 DIM ¥¢5>: Dim N¢S> :POKESS459, 255:P=S9d71:> REM USER FORT OUTPUT
10@ PRINT"WHEN YOU FEEL A SHOCK" * Circle No. 192

{G5 PRINT"RESPOND WITHIN 5S SEC WITH: "

110 PRINT’1=JUST MOTICED Z=EASIL'Y NOTICED" DATAPLUS

{15 PRINT"Z=UMPLEASANT 4=PAIMFUL 9 S=VER'Y PAINFUL" BUSINESS SYSTEMS

15@ FORJ=8TOS: ¥6J9=0:N¢J2=@:NEXT PROGRAMMED
28@ FORM=17036 > V=INT<(255#RNDC 12>: GETAS SUPPLIED AND PRO

218 POKE PV: FOKEP.G rr TO YOUR REQUIREMENTS

228 FOR J=aTOJ=5@@a: NEXT: GETAS :A=YAL CAS) > IFAD 30

238 VOAD=VCAD FY HEAD SHCA +L: BUY/LEASE .

248 FORJ=A@TO1GH04RHD¢ 1 >> MEST? NEXT Dataplus, 67 Bridge Street,

228 FORT-ST05: LFNCJ=@THENNC J 291 -. a ; Manchester M3 3BQ.

Bi@ NEXT: VESINT © VES) CHCS) +24Y 04 ANOS 948 CSI AHC5 0 972. 55 3

228 PRINT"THRESHOLD 13 "VF" VOLTS" | Telephone 061-832 3265

READ". ® Circle No. 193

PRACTICAL COMPUTING January 13980 109

meee chop Window

DATA
PROCESSING
JOURNALIST

Data Processing, the international
monthly magazine for computer
managers, requires a journalist to
join its small, lively team.

He/she will have a busy and varied
working life which will include the
origination and writing of business
{and technical articles, subbing, proof
‘reading, attending press confer-
ences. Salary: £5,771.00 plus reading
allowance of up to £210.00 per
annum.

Write, with full details to Sarah
Hardcastle, Editor, Data Processing,
IPC Electrical-Electronic Press Ltd.,
79/80 Blackfriars Road, London SE1
8HN. Tel: 01-261 9111.

The salary and conditions quoted are
in accordance with the IPC/NUJ
agreement.

¢ Circle No. 194

¢ Circle No. 195
TRS-80 System

All items stocked, Barclaycard,
Access & American Express are
welcome, or apply for your own
RADIO SHACK Charge Card.
U.K. Delivery by Securicor.

Direct and Personal Exports.

RADIO SHACK LTD.
188 Broadhurst Gardens,
London NW6 3AY.

Tel: 01-624 7174 Telex 23718
¢ Circle No. 196

ULTRA FAST CASSETTE INTER FACE BOARD
FOR THE NASCOM | providing reliable data storage
and recall at up to 7,800 baud!! on standard cassette
recorder.

e.g. 1K of data loaded in less than 1% seconds!!

The modifications required are minor and ful!
documentation is supplied with each board which
comes built, tested and guaranteed.

For immediately delivery send £15.95 + 35p PEP to:

JC Hunter
85 Portland Street, TROON,
Ayrshire, Scotland
or telephone 0292-311613 evenings.

110

BUYERS’

The Buyers’ Guide is a summary of low-cost

computers available in this country. It appears

each month; we add new computers and
amend existing information, as required, to

keep it up-to-date. Systems are listed by manufacturer.

ACORN COMPUTERS

Acorn. Single Eurocard-sized microcornputer with 6520 processor,
IKB RAM, 16-way I/O. Max size; a second Eurocard adds hex keypad
and CUTS cassette interface. Monitor and machine-code. prog-
ramming now Basic and disc operating system in the future. ‘Highly
cost-eltective basis for a computer or an industrial development
system”. Available from Acorn (0223) 312772 or Microdigital (051,
236 0707.

£74.75 kit, £86.25
assembled

APELEMGOMPUTLERS

Apple Il. Min size: 16K memory; 8K ROM; keyboard; monitors; mini
assembler; colour graphics; Pal card; RF modulator; games; paddles
and speakers; 4 demo cassettes. Max size; Expandable to 48K
memory; floppy discs and printers are now available. Two versions of
Basic, PASCAL; Assembler, games; business packages. An American
system regarded as suitable for any kind of aplications. Maintenance
contracts offered Microsense Computers is the sole U.K. distributor
and has 4 national dealer network. Tel: (0442) 41191/48151 (24-hour
answering service)

Around £1,000

ATTACHE

Attache: Min size: system with 10 slots, S100 bus, 8080 processor
and 16KB housed in desk-top case with built-in keyboard. Max: 64KB,
parallel printer interface, two single or double density 8” floppies,
video screen. Disc Basic. Full business system includes all software.
Mecotronic is UK agent south of Birmingham. Tel: (0276) 29492,
R. J. Spiers, 3 Birch Court, Woodlands Garden, Norwich, north of
Birmingham.

From £1737. Full
business system
‘000

BILLINGS

Billings Microsystem (BMS): Z-80A, 64K RAM, 12" screen,
QWERTY keyboard, range from double density 8” floppies (600KB),
to 200 MB hard disc. Software includes COBOL (ANS174 with ex-
tensions), FORTRAN, Extended BASIC and MAC80 Assembler. The
microsystem could be used as a program development aid. Avail-
ability: Mitech Data System Ltd, Woking (04862) 23131.

From £4295

BRUTECH ELECTRONICS.

BEM-CPUI. Single-board processor with 6502 and no RAM.
Applications software. Available from Data Precision Equipment
(04862 67420). (Reviewed March, 1979.)

£133 exc VAT

PRACTICAL COMPUTING January 1980

= 2a Buvers' Guide sess

BYTRONIX MICROCOMPUTERS

Megamicro. 8080A/Z-80 processor. 64K. Double-sided discs, two-
page addressable VDU, 140 cps printer. Software includes Basic,
Fortran, Cobol and Pascal, all running under CP/M. Applications
include automatic letter writer, sales ledger and stock control, payroll
and bought ledger. Self-diagnosis utilities. Aimed at business and
university user. Available from Bytronix (0252) 726814.

From £6,080.

COMART

Microbox: Chassis with three to six PCB sockets for $100 boards,

plus fan. Several $]00 boards available. Aimed mainly at OEM indus-

trial users and perhaps the serious hobbyist. It will'take Cromenco,

ons Star and other processors. Available from Comart (0480)
50085.

VDM Board: Adds word processing power to the S100 bus by

providing on-board screen storage. Generates 16 by 64 character
lines from data stored in a 1024 byte on-board memory.

£195

£145

COMMODORE SYSTEMS DIVISION

Pet. Single unit containing screen, tape cassette and keyboard.
Floppy disc, printer and full-size keyboard are options, as are external
cassettes. Basic; games; business packages. The British subsidiary of
Commodore Systems of the U.S. sells Pet for home, educational and
small business applications. About 80 distributors.

Kim-1, processor (6502 chip); small calculator-type keyboard; LED
six-digit display; built-in interfaces for audio-cassette and Tele-type; IK
RAM; 2K ROM (can add up to 64K). No software available, but it has
three good manuals. An American import which gives Pet-type
capabilities with a maximum configuration. For the hobbyist but used
mainly as an evaluation board for the 6502 chip. Twelve to 15
dealers. (Reviewed October, 1978.).

£460-£795 exc
VAT

£99.95

COMPELEC ELECTRONICS

Series I. Z-80 processor 512MB floppy, 32KB, Centronics printer,
VDU. Up to 4MB disc and 64KB. CP/M, Basic, Cobol, PASCAL, For-
tran IV, Assembler, Business and word processing packages available.
From Compelec (01-580 6296), which 1s also sole supplier of Altair
systems.

COMPUCOLOR

Compucolor II. Packaged system including 13in. eight-colour dis-
play with alphanumerics and graphics, 72-key detachable keyboard,
8KB, and bult-in mini-floppy. Max size: 32KB. Extended disc. Basic in
ROM, ‘graphics progams and games. The system row ranks fourth
behind Pet, TRS-80 and Apple in personal computer sales. Abacus
(01-580 8841) is sole U.K. agent and is arranging distributors,
including the Byte Shop and Transam, (Reviewed lune, 1979.)

COMPUCORP

Less than £5,000
for basic system

from £1,390

610: desk-top unit using Z-80 and incorporating screen, 150KB
floppy, 48KB. Up to 60 KB memory, four floppies, printers. Basic,

ae DOS, text editor, file manager; business packages. Nine
ealers.

COMPUTER CENTRE

Mini kit: Z:80 CPU, CTC, USART, serial and parallel I/O, 16 bytes
memory, Western Digital disc controller, SA400 Sin. drive plus CP/M,
cables and cornectors.

Maxi kit: As above but with DRI 7100 8in. drive instead of Sin.
drive. All (33) volumes of CP/M user group library available for cost
of media. Library includes utilities, games. Basic compilers/inter-
preters and Algol compiler. Microsoft Basic, Cobol, Fortran also
available. Computer Centre (02514 29607). ‘

PRACTICAL COMPUTING January 1980

From £3,890

Mini kit: £786

Moxi kit: £886

Shop Window

Vets for Pets

Anita Electronic Services (London) Ltd.
are specialists in the repair and service of
Commodore Pets.

= We offer a fast on-site service, or alter-
= natively repairs can be carried-out at our
= workshops should you wish to bring In
= your Pet.

= Pet maintenance contracts are available
= at very competitive prices. Trade inquir-
= ies welcomed.

UUUUTODVODODERSODODO LE

For further information tel. or write to:-:

John Meade
Anita Electronic Services,
15 Clerkenwell Close, London ECI
01-253 2444

° We also specialise in the repair of all
= makes of office equipment.

COMMODORE
PET
SPECIALISTS

We stock the Commodore
range of equipment and have a
large selection of high quality
software to go with it.

We also have programming
facilities and fast reliable main-
tenance support.

In stock is a selection of
secondhand and ex. demon-
stration machines all guaran-
teed.

Give us a Call first to see what
we have to offer.

DAVINC!] COMPUTERS LTD.
Tel: 01-202 9630 j
Classic Offices

Rear of Classic Cinema
Hendon Central

London NW4.

VULTVUUUERRNTUAUNONDDODNNENNAL
VOLVUNEGUUSGOORROAGRNEGOAUUECOCUGDSONONEDSOUOEOONOUOERONUOUGEAOUEN SULURCOH ES

Da Vine CH

° Circle No. 199

PROGRAMMER

WANTED

for small software house, to work on
interesting assignment developing
specialised accounting system. Personal
service and involvement essential,
London area. Please give details of
experience and method of charging to

Box No 102

Programs for minimum Nascom-1
— Fruit Machine Game

— Submarine Chase Game

—Game of Life

—Minefield Game

Programs for extended Nascom-1
—Renumber Basic Program

All supplied fully documented with

£3.45
£3.45
£3.45
£3.46

£4.60

listings on B-Bug, T4 or Nasbug
format cassette tape.

C20 cassettes (inc. library §

£2.76
cases) 10 £4.83
Machine code, Assembler or Basic codin
forms. £1.60 each pad (approx. 80 sheets).
Add 35p for p&p, all prices include VAT.
Send SAE for details:
21 Lime Tree Drive, Farndon, Chester

¢ Circle No. 201

111

me Op Wc 0 guerra era

Philips

Mini Digital
Cassette Recorder
UP TO 128K SERIAL MEMORY
HIGH SPEED — LOW COST
SPECIFICALLY DESIGNED
FOR DATA STORAGE &
INTERCHANGE
READ, WRITE, IDLE,
FORWARD AND REVERSE
FACILITIES
IDEAL TO INTERFACE TO
YOUR MICRO
£95 EA. + VAT (£1.50 FOR
P.& P.

INTERFACE CARD TO PROVIDE ALL
NECESSARY INPUT AND OUTPUT
FACILITIES TO ENABLE FULL
AUTOMATIC CONTROL OVER THE
TAPE UNIT.

PRICE £37.50 EACH

(CIUIRIRIATH) conronenss

79 Crowiand Rd. Hartlepool Cleveland.
TS 242JN. Phone 0429 / 871900

¢ Circle No. 202

Some people
would give

anything to have

your

micro experience

If you have solid experience on
Intel 8080 or similar and are
interested in contract work
Richard Kaluzynski will putyou in
touch with them.

Knight Computer Services Limited,

14 Old Park Lane, London WIY 4NL.

Tel: 01-491 4706.

Knight
4(]L4 4

Staff Services Division of BOC Datasolve Group
and E/E a member of Computing Services

Association

¢ Circle No. 203

Fed having to return tapes that won't
ds

loa

TRY THE QUALITY OF
KANSAS

High density tapes with comparable mechanics
and everything actually produced at our works
down to the labels and library cards (yes
library cardsl).

TANDY LEVEL I! — send for catalogue

(Kansas Kansas

112

City Systems

Unit 3, Sutton Springs Wood, Chesterfield
Tel (0246) 850357
(21 years in media production)
We publish programs on a royalty basis

¢ Circle No. 204

COMPUTER WORKSHOP

System I. Typical size: 40K memory; dual 8in. floppy disc, total
storage capacity 1.2MB; Ricoh daisywheel printer.

System 2. Typical size: 24K memory; dual minifloppy discs of BOK
bytes each; Centronics 779 dot matrix printer; VDU.

System 3. 12K memory, cassette interface; 40-column dot matrix
printer. Editors, Assemblers, Basic, games, information retrieval
package. The systems were designed and built in Peterborough and
are suitable for educational and small business users and perhaps the
more serious hobbyist. Twenty-five dealers.

System I. £5,000

plus

System 2, around
£3,000

System 3, from
£1,300

CROMENCO

Single-card computer: 4MHz Z-80 CPU, S-100 bus, 1KB RAM,
sockets for 8K ROM. 20mA/RS232 serial interface and_ parallel
bidirectional interface. Basic in ROM and Z-80 monitor. For OEM and
industrial users; used with backplane for “full computer compatibility”
(Reviewed February 19779).

Z-2: Min. size: chassis, 3] A power supply, motherboard, Z-80 pro-
cessor, 16KB memory. Max size: 512KB, 21 sockets, three mini-
floppies or four 8" floppies. Basic, Fortran, Cobol, assemblers. For
serious hobbyists, OEMs, educational applications, and industrial/
scientific userers.

System Two. Min size: factory-assembled system with 32KB, dual
9OK minifloppies, dual printer interface, serial interface. Max size: two
additional floppies, 512KB, up to seven terminals, CP/M-compatible
operating system (CDOS), Fortran, Cobol, Basic, assemblers, word
processing, database manager. Multi-user system for software
development, or scientific/industnal/business users.

System Two/64: 64KB, dual 90K mini-floppies, dual printer inter-
face, serial interface. Options: two additional floppies, 512KB, up to
seven terminals, CP/M compatible operating system (CDOS), Fortran,
Cobol, Basic, assemblers, word processing, data-base manager. Multi-
user-system for software development, or scientific/industrial/business
users.

System Three. Min size: 32KB, dual 256KB floppies, dua! printer
interface, 20mA/RS232 serial interface, Z-8O processor. Max size: two
additional discs, 12KB, seven terminals, multi-channe] A/D and D/A
interlace, PROM programmer. Software as for System Two.
Described as appropriate for small to medium business, scientific and
industrial users -— “rivals minicomputers at more than twice the price”

System Three/64: New configuration featuring dual 8” floppies,
Z-80A processor, 64K of 4MHz memory; console and printer inter-
faces. Macro assembler, Fortran IV, Extended Basic, Cobol, Multi-
user Basic. All systems sold by Datron Interform, Comart, Micro
Centre. Prices quoted by Comart.

£225 (in kit form)
to £260

£360 (in kit form)
to £37

£1,995 upwards

£1995 upwards

£2,995 to more

than £8,000

£3270

DIGITAL MICRO SYSTEMS

DSC-2. Min size; 32KB, but 64K standard; Z-80; over IMB floppy disc
on two single-sided 8in. drives; four programmable RS232 and one
parallel interface. CP/M and Basic included in price. Extended Basic,
Fortran, Cobol, text processing, Macro Assembler, Link Loader,
business packages and CAP-CPP business software. Add-on rigid disc
system (14 and 28MB) available soon. Modata (0892 39591) is sole
U.K. distributor; dealers being appointed.

From £4,465

DYLE HOUSE

Business Computing System 2000. Z-80A. Dual 8in. discs, 140
cps 132 char printer. Dyle House Business Basic, and disc operating
system. Accountancy, payroll and parts control suites. Applications:
Sales acknowledgments, sales invoices, delivery notes, purchase
orders, customer statements, remittance advice. Dyle House Ltd
(01-529 2436).

No price
announced

PRACTICAL COMPUTING January 1980

ees Buyers’ Guide mmm Shop Window gags

INTELLIGENT

EQUINOX

ARTEFACTS

Equinox 300. Min size; 48K memory; dual floppy discs giving 600K
bytes of storage; 16-bit Western Digital m.p.u. Max size; up to 256K
memory; up to four }OMB hard discs. Basic, Lisp, PASCAL, Macro
Assembler, Text Processor. All software bundled. The system is a
multi-user, multi-tasking, time-sharing system for two to 12 users.
Application software available for general commercial users. Sole
distributors Equinox Computers Ltd (01-739 2387).

S100 16K static RAM boards in
£5, 000-£40, 000 stock

plus — INCREDIBLE VALUE £150
Z80 CPU cards 4MHZ £100

We import direct from U.S.A, under-
cutting all competition on PETs, Ohio
Scientific, $100 ete.

Phone fdr prices: Arrington (022020) 689

Intelligent Artefacts Ltd,

EURO-CALC

Cambridge Road,
Orwell, Nr Royston, Herts

Euroc: 8080A CPU, 64KRAM, two times double-dsided single-
density 8" floppy disc drives with approximately 1 MByte capacity.
15” screen with 80 by 25 characters, QWERTY keyboard. CP/M
operating system 140 CPS tractor feed matrix printer. Software:
C-BASIC 2. Supplied with accountancy package for sales, purchases
and nominal ledgers and initial stationery. Sold through Euro-Calc,
55/56 High Holborn, London W.C.1. Tel: 01-405 3113.

EXIDY

Sorcerer: based on Z-80, 16K and 32K; cartridge and cassette inter-
faces; 79-key keyboard; 256-character set (128 graphics symbols),
12in. video monitor; expendable with Micropolis floppy discs. Basic,
Assembler and Editor; games, word processor. Other pre-packaged
programs plus EPROM Pack for your own programs on cartndges.
Factor One is sole distributor for U.K. (Reviewed March, 1979.)

® Circla Na onc

£8000 -
Ni9e) Roberts and RoY Trubshaw would like
to announce TheY are now trading asi-
(ATH) cheap,nigh quality softwore with full
paint:
or speciality,
~~ mo ey y fer: SUPERWOMPUS
without VDU to as Ors Sra SUE :
£1,200 with ee

Lombdo Systems
P.0. Box #9.

i]
Colchester.Cow 3SF e

floppy discs

HEATH SCHLUMBERGER

H8. 8080 CPU. 4664K PAM. Serial/cassette I/O; front parallel
monitor; keypad; optional parallel I/O; serial multiport; breadboard
I/O and disc system. Basic, Ext. Basic, Mierosott Basic, HDOS, CPM.

WHBS9. All-in-one computer. 2-80 processor plus Z-80-controlled
VDU. 16K expandable to 48K, user-accessible. Two RS232 I/O ports.
Operating system includes Benton Harbour Basic, two-pass absolute
assembler, text editor, utlity programs, Mierosoft Basic and Fortran
word processor package. Heath Schlumberger (0452 29451).

PET’s
an £262 (in kit +
a SHARP MZ-80’s
(THE NEW MICRO)
+e

HEWLETT-
PACKARD

About £1,600

HEWART MICROELECTRONICS

HP-41’s

Mini 6800 Mk II. IK momtor; IK user RAM, IK VDU RAM; CUTS
Upper- and lower-case VDU with graphics option. 128-byte
scratchpad; decoder/bulfer; power supply; Basic in ROM; monitor
command summary. SWTPC programs; Newbear 6800; Scelbi 6800
Cookbook. Markets are small business, education and home user.
Cash with order to Hewart. (0625) 22030.

6800S. 16K dynamic RAM; IK Mikbug-compatitile monitor; recom for
BK Basic in ROM; upper- and lower-case graphics; single floppy disc
drive; printer and high-speed tape interfaces. “Mountains of software
available.” Test tape with CUTS test tones, test message and games
with kit.

+
COMPUTER
BOOKS

From £127.50
plus VAT

SIGMA SYSTEMS

54 PARK PLACE
CARDIFF 21515

From £275 plus
VAT

IMSAI

VDP 40: 32K or 64K RAM memory; Qin. display screen, standard
keyboard. Two 5'ain. floppy disc drives; serial I/O. Full software
support, and packages available for the VDP 42, which has larger disc
capacity. Packages for VDP 80 could be converted for smaller
systems. This would be from about £700 per package. Two main
dealers in the country

¢ Come and see these fine computers
in our new showrooms.

¢ Try them and discuss your require-
ments.

Sensible Software for Apple

£4,507 for 32K
model. £4,950 for
VDP 42

¢ Invoicing/ Debtors’ Ledger
¢ Financial Modelling.
¢ Shape maker

ITT

¢ Educational systems; maths; physics;
commerce.

2020. Identical to Apple II. Min. size: 4K memory; 8K ROM;
keyboard, monitor, colour graphics, mini assembler; Powell card; RF
Modulator, games, paddles and speaker; Max size: 48K with floppy
discs and printers. Basic, Assembler, games, business packages.
Generally suited to any type of application. Fifteen wholesalers,
including Fairhurst Instruments.

PRACTICAL COMPUTING January 1980

From £827 to
£3003 for 48K,
two floppies and
printer

SOFTECH LTD
51 Lower Camden Street,
Dublin 2

Tel: 01-976279

® Circle No. 208

113

TOPMARK
Computers

dedicated to
APPLE |

Simply the best!

Full details from Tom Piercy on
Huntingdon (0480) 212563 or circle
enquiry card.

® Circle No. 209

ASR TELETYPE 33’s
£250 + VAT

Secondhand Serviced
30 Day Return to Workshop Guarantee

Also available:

@ Fitted Silencing Cover for above
@ 10-30c.p.s DIAN KRS/ASR

@ 10-20 c.p.s Log Abdx Lx180 KSR
@ Acoustic Couplers

Enquiries to:
Derek Lade 01-637 1355 (S. England)
Ken Pickford 0772 686010 (N. England)

ADP Network Services
179-193 Great Portland Street
London W1N 5TB

ANTIQUE
* DEALER *

requires accounting programs, including

provision for the special VAT scheme for
antique dealers, also preferably provision
for foreign exchange. Details please to

Box No 101
@ Circle No. 211

Bought, sold or exchanges
(repairs as well)

MICRO HIRE

Pets; Apples, Sorcerers; Horizons; Printers
and floppy disks etc.
We also stock Horizon and Apple.
Low prices and free deliveries
Mon — Sun — evenings
Promglow Ltd
01-388 9002

114

LUXO

ABC 80. Min size: 35K with keyboard, CPU 12in. screen and cassette.
Max size: 40K RAM with discs. Z-80 processor, loudspeaker with 128
effects, real-time clock. Options: printers, plotter, discs, module cards,
digitiser, modem. 60 compatible /O memory boards. Software: Basic
with resident editor; assembler:. games; business and educational
packages. Personal computer aimed at home market, small business
and education. CCS Microsales is U.K. agent and is looking for
distributors.

£795 plus VAT

MICRONICS

Micros. Typical size: IK monitor; 47-key solid state keyboard; inter-
faces for video, cassette, printer and UHF TV; serial I/O, dual parailel
VO parts; 2K RAM; power supply. 2K Basic; British-designed and
manutactured system. Claimed to be the cheapest data terminal — a
system with an acoustic coupler and VDU for £1,020. Prospective
applications for small businesses, process controllers and hobbyists.
Manufacturer is sole distributor (01-892 7044).

MICRO V

Microstar. Single box with twin 8in. flopy discs, 64K RAM, three
RS232 serial inputs, STARDOS operating system enables system to
have three VDUs, plus a fourth job running simultaneously. Word
processing software available. Packages being developed include
invoicing system, payroll, accountancy type system. Price includes a
reporter generator language. Imported by a “Data Efficiency
subsidiary, Microsense Computers, Mictosolve is London agent; other
distributors being arranged.

MIDWEST SCIENTIFIC
INSTRUMENTS

MSI 6800. Min size: 16K memory Act | termnal; cassette interface.
Max size: three disc systems — minitloppy system with triple drives of
80 bytes each and 32K memory, large tloppy system with up to four

'312K-byte discs and 56K of memory mounted in a pedestal desk, or

hard disc system with OMB and 56K Basic interpreter and compiler;
editor; assembler; text processor on small disc system. American-
designed system being manufactured increasingly in the U.K. Sole
U.K. agent is Strumech (SEED) (05433 4321) but a distnbutor
network 1s being established

NASCOM MICROCOMPUTERS

From £400,

assembled

£4,950 machine
and software

Basic system:
£1,100 (£815 as
kit); Minidisc,
£2,500; floppy
disc £3,200; hard
disc, £8,000-
£12,000

Nascom I. Min size: CPU; 2K memory; parallel I/O; serial data inter-
face; IK monitor in EPROM. Max size. CPU, 64K memory, up to 16
parallel /O ports. Mostly games, but also a dedicated text editor
system written by ICL Dataskil Nascom is working on large versions
of Basic, and 8K Microsoft Basic should be available soon. Eleven
distributors in U.K. Nascom is negotiating to increase the number.
(Reviewed January, 1979.)

£165 exc VAT

NATIONAL MULTIPLEX

Pegasus. Min size: 48K, Z-80; double-density floppies (320KB); S100
bus; 12in. CRT; 58-key keyboard; two serial and one parallel inter-
faces; bi-directional printer. Options: 8in. drives; 1-2MB additional
drives; digital recorder 9,600 baud. Assembler, Cobol, Fortran,
Extended Basic. General business package available as well as text
editing and mailing list. All run under CP/M. Suitable for education,
psn and home users. London Computer Store (01-388 5721) sole
supplier.

NETRONICS

£2,700 exc VAT

Elf II: single-board computer in kit form or assembled. RCA Cosmac
1802 processor, hex keyboard, 256 bytes RAM; options include up to
64KB, ASCII keyboard, cassette and RS232 I/O, and video output.
Machine code or Tiny Basic. Promoted as a teaching system in
minimal form, but expandable for more general use. Sole U.K.
distributor HL Audio (01-739 1582).

Basic kit £79.95.
Assembled
£99.95. I/O board
£35

PRACTICAL COMPUTING January 1980

es Buyers’ Guidcmmmmms Shop Window gus

Explorer 85; Min size: 4K. Max. size: 64K. 8085A processor, VDU
board, ASCII Keyboard, S100 expansion. Cassette, RS232, TTY
interface on board. I/O ports, programmable timer. Disc software,
Microsoft Basic on cassette, 8080 and Z-80 soltware can be used.
Aimed at hobbyist, OEM and small business. Available from New-
tronics (computer division of HL Audho).

NEWBEAR

7768: CPU board, 4K memory, cassette and VDU interfaces. Range of
Basics and games. British manufactured system for hobbyists. Expand-
able to 64K memory available only in kit form. From Newbear in
Newbury and Stockport.

NORTH STAR

Horizon. Min size: 16K memory; Z-80A processor, single minitloppy
disc drive (18OKB), Max size:’ 56K memory, tour minitloppy disc
drives (180KB), any acceptable S100 periphere! boards. Basic
(includes random and sequential access), disc operating system and
monitor. Options: Basic Compiler, Fortran, Cobol, Pilot, PASCAL and
ISAM. The system is suitable tor commercial, education and scientific
applications. Application software tor general commercial users.
Twenty distributors. (Reviewed Apnil, 1979.)

OHIO SCIENTIFIC

From £297 plus
VAT

From £45

£995 to £2, 500

Ohio Superboard II. Min size: 6502 processor, 8K Basic in ROM;
2K monitor in ROM; 4K RAM; Cassette I/F, full keyboard; 32 x 32
video I/F, 8K Basic in ROM; Assembler/Editor; American single-board
system with in-board keyboard. Aimed at hobbyist/small business.
Ohio makes games, personal maths tutors, and business programs.
This and other Ohio products have six U.K. distributors. (Reviewed
June, 1979.)

From £298

PERTEC

System 1390. Min size: 32K memory; dual minitloppy discs 71 bytes
each, formatted; serial interfaces. Max size: 64K memory; four serial
parts. Basic (single and multi-user), Fortran, Cobol. The hardware for
Compele= Altair systems is from Pertec but the software is Anglo-
Dutch. Sole distributor Compelec (01-580 6296)

£3,000-£5, 000

POWERHOUSE MICROPROCESSORS

Powerhouse 2: Desktop unit using Z-80A with 5” built-in VDU and
built-in minicassette (optional), 16K or 32K RAM, full keyboard, real-
time clock, two spare slots, RS232 interface. Software: Disc and
cassette operating system, programmable keyboard facilities for eight
PROM chips giving a max of 16 or 32K or ROM, 2K monitor in
EPROM. Extended basic (optional). Aimed at OEMs and expert users
such as scientists or researchers. Applications include real-time pro-
cess control, engineering calbulations. Availability: Powerhouse only
(0442) 42002. (Reviewed, September 1979).

From £1200

PROCESSOR TECHNOLOGY

Sol. 808-based S100 microcomputer packaged with cassette and
video intertaces (including graphics), keyboard with numerics pad, and
16KB RAM. Basic, assembler, word processors. Floppy disc systems
available. Several distributors including Comart (0480 215005),
He can offer nationwide maintenance contracts (Reviewed July,
979.) ‘

RAIR—

Black Box. Min siz: 32K memory dual minifloppy discs, 80K bytes
each; two programmable serial I/O interfaces. Max size: 64K memory;
eight serial interfaces; IMB disc storage (or 1OMB hard disc); range of
peripherals. Basic, Fortran IV, Cobol, Hardware distributors are
being signed and agreements made with software houses to add
software. A warranty and U.K.-wide on-site maintenance is given.
From manufacturer (01-836 4663) and systems houses.

PRACTICAL COMPUTING January 1980

From £1,750
(excluding monitor
and cassette).
Complete floppy
disc systems with
word processing
about £5,000

From £2,300

EXIDY SORCERER

32K Micro Computer

£859.00+ VAT
Dealer for

Bristol and
South West

ELECTROPRINT (Mr, Tasker)
5 Kingsdown Parade « Bristol6 »« 292375

¢ Circle No. 213

6800 — 5 BUS.

32K Dynamic Ram Kit
available in 16K form at £130
and only £200 for 32K

6800S The world’s most
powerful single-board 6800-9
computer kit. 16K version with
keyboard £299.

Mini 6800 multi-board
system from £127.50. All
prices without VAT and post
SAE for leaflets to: Hewart
Microelectronics, 95 Blake-
low Road, Macclesfield,
Cheshire SK11 7ED.

NASCOMS 1 & 2

Up to 10 Channels I/O Board.
Other I/O Boards soon.
S.A.E. to:

BING SYSTEMS

8 Glen Road, Bin ye
West Yorks., BD16 3ET.

ENERTECH

ITHACA $100
and tested P.C. Boards with documentation
Hz

8K Static RAM
8K Static RAM
2708/2716 EPROM
VDU 60/60Hz
Floppy disk controller
DPS-1 mainframe with ZBO CPU 4 MHz, front panel,
20 slot motherboard, 254 power suppty and fan £695.00
VERO $100
Sub rack with 6 slot motherboard, fittad connectors,
power supply and cooling fan £233.00
ENERTECH FIRMWARE for systems using Z80 CPU
MAPP 1-42
A relocatable floating point arithmetic and functions
package, 40-bit format, range +/-1E+/-38, generates 43
additional object codes for use with ZBO object code,
input/ interpret & output ASCil decimal with choice of exp.,
binary read and write, push, pop, and relative jumps Can be
used on systerns with less than 1K RAMI
Manual onty
Four 2708 EPROMS with manual (4K)
As above but assembled on ITHACA $100
EPROM Board b
TERMS: Above prices exclude VAT and delivery. Please
add VAT at 15% (except a marked °) plus 1% carriage
and send your cheque or P.O. to:
ENTERTECH LTD., 32 GILDREDGE ROAD,
EASTBOURNE, EAST SUSSEX, BN21 4SH
TEL: (0&23) 870814 (24 hour answering service. )
C.W.O. Proforma invoice service for official orders.

Security delivery at cost.

ENGINEERING DEVELOPMENT SERVICE AVAILABLE
Above prices correct at time of going to press, subject to
change without notice.

115

Q-SOFT Are Now Selling Direct
As the king surveyed his tired but
victorious army he pondered his next
move. He had. just regained Somerset
from the Roundheads at a cost of 60,000
men and 56 cannons. The scouts report
troops and archers hidden in the Devon
Woods — should he push on with his
weary troops or await reinforcements
from Norfolk? ;
Put on the crown yourself and play the
best-selling “Civil War’’
Now available for TRS 80 — Apple —
Sorcerer and PET. ,

£7,50
In-’’Matchplay Golf’ you play a round of
golf with the opponent of your choice.
You‘ve got to be good to win. Drive off
and see your ball lazily sail 250 yds. and
land .. . ina bunker. Great graphics!

_ (PET 67250

And many more — send for list to: —

Q-Soft
315, Toller Lane, Heaton,
Bradford 9,
Yorks.
Phone Bfd. 23500

We do not boast the largest selection of
software but what we have is Smooth!
Dealers enquiries welcome.

THE BEST. FOR LESS!
Computers, Firmware,
Software
Most Makes Bought,
Sold, Exchanged,
Constructed.

PET ITT ELF & NOW

. NEW SHARP!
PETSOFT & GEMSOFT
€xamples of low, low prices: —
Teletext Decoder £215. Grandstand
Games Computer £115.
Sharp 10K £499; 18K £599; 22K £619;
34K £699. All plus VAT/Carriage.
OPTELCO
PHONE: RAYLEIGH (0268) 774089

_UPTO8pm

QWERTY. CO

MPUTER
SERVICES
NEW
PET Cassette Interface — use your own
cassette and save over £25.

ONLY £25 ‘
5v, 1A power supply £16.50
T.V. Interface — £20.00
Switcher £10.00

Amplifier plus music program £15.00
Software for PET, Apple and TRS 80 QCS,
Petsoft, Gemsoft etc.)
SPECIAL OFFER: any four QCS programs
for £10.00.
SEND OR ‘RING’ FOR DETAILS
QWERTY COMPUTER SERVICES
20 WORCESTER ROAD NEWTON HALL, DURHAM
TEL: (0385) 67045 _

WORD-PROCESSING

written by C.B.C. for

APPLE & ITT 2020

cassette: £20 disc: £26 + VAT
inc}. Documentation, For Anadex, Centronics etc.

Sénd Cash, Cheques, P.O. or Access/ Barclay
No, for €23/£30 (incl. VAT and P&P) to:

MILDMAY ELECTRONICS (Dept. A)
200, Moulsham St., Chelmsford, Essex

® Circle No. 220

116

¢ Circle No. 218

Shop Window guesses

RESEARCH MACHINES LT

380-Z. Min size: 4K memory; 380-Z processor, keyboard. Max size:
56K memory. Options: cassette, single or dua] mimfloppy discs, dual
8in. double-sided discs (IMB); serial interfaces; parallel interfaces;
analogue interface; printer available. Basic Interpreter, Z-80
Assembler; interactive text editor; terminal mode software; data
logging routines; CP/M, DOS, text processor, CBasic, Fortran, Algol,
Pilot, Cobol, CP/M users’ club hbrary. Sold principally to higher and
secondary educaton, and for scientific research, data processing and
data logging. Available from Sintel and the manufacturer. (Reviewed
December, 1978.)

280-Z. Board version of 380-Z system, 4K or 32K (identical in perfor-
mance to the 380-Z). Interfaces, software as for 380-Z.

From £830-£3, 500

4KB version at
£398; 32KB for
£722

RCA

Cosmac. 1802 micro with hex keypad and output to TV screen.
Assembler and machine code programming; options include Tiny
Basic. Available by mail order from HL Audio (01-739 1582)

ROCKWELL

Kit £79.95.
Assembled £99.95
exc VAT

Aim-65. Kim-compatible with full keyboard and on-board printer. 1K
or 4K RAM. The 4K version is described as a development system
rather than a personal computer. Assembler, editor, Basic. Available
sisi Pelco, Microdigital and Portable Microsystems (Reviewed July,
1979.)

iK — £249.50
4K — £315

SCIENCE OF CAMBRIDGE

Mk 14. SC/MP processor, 256 bytes user memory; 5] 2-byte PROM
with monitor program; hex keyboard and eight-digit, seven-segment
display; interface circuitry; 5V regulator or board. To this can be
added: ¥«K RAM (£3.60); 16 I/O chip (£7.80); cassette interface kit
(£5.95); cassette interface and replacement monitor (£78.95); PROM
Programmer (£9.95). No software provided but a 100-page manual
includes a number which will fit into 256 bytes covering monitors,
maths, electromics systems, music and miscellaneous. Based on
American National Semiconductor cnips. Science will soon have a
VDU Interface and large manual on user programming. Mail order
from manufacturer (0223 312919) and by selected dealers.
(Reviewed May, 1979.)

£39.95 basic

SDS

SDS 100. Single unit containing 32K memory (expandable to 46K);
up to 8K PROM; twin double-sided floppy disc drives of 500 bytes
each, serial and parallal RS232 interfacing; keyboard; 12in. video
display; power supplies; SD monitor program: line printer available.
CP/M, 8080 assembler, E Basic, Editor supplied with system; M Basic,
Fortran, Cobol available for business use, industrial process

_monitoring and control (with additional hardware). All CP/M games

and business packages. Sole supplier Airamco (0294 65530).

From £3,750

SEMEL

Semel I. Min size: 4K with CPU, keyboard and monitor. Max side:
64K with single floppy disc unit, printer, VDU and keyboard. Can be
coupled to any external device and controls up to 8 x 250K floppy
disc units. Four configurations available. Options: Light pen
attachment; 12V DC power supply; remote terminals. Software:
Editor, Assembler, debug, full file-handling capabilities in Basic,
Fortran and Cobol available on 64K machine; user-defined programs
written and compiled by agreement; word processing. General-
purpose unit for use as a terminal controller. Suitable for small
business and OEMs. Available from Semel] exclusively (0822) 5439.

£1,950 with Basic

PRACTICAL COMPUTING January 1980

es ors’ Guide =

—$<—<$<

SOLID STATE TECHNOLOGY INC.

Athena Dt/C 8200: Eight-bit 8085 desktop computer with in-built
dual mini floppies, inbuilt dual mini-cassette, inbuilt matrix printer and
1920 display. Can be expanded with 10 micros, beyond the CPU,
each working as an intelligent controller, up to four floppy disc drive
and four rigid disc drives. Maximum memory is 1.2GBytes. Standard
system software is the AMOS multi-task operating system. Claims a
performance roughly comparable to the DEC PDP-11/34. Butel-
Comco, Southampton (0703) 39890, are the sole U.K. distributors.

SORD

M100. Min size: 16K RAM; 4K ROM Monitor; full keyboard plus
function keypad; two-channel joystick dual cassette I/F; 11K E Basic
on cassette; video; graphics; printer; S100 bus; converters; speaker;
24-hour clock. Max size: 48K RAM, 8K ROM; black and white or
colour graphics; mini-floppy discs. Suitable for OEMs, small business,
educaton, laboratory and scientific and home computing. Main
distributor is Dectrade, but for London and South contact Midas
Computer Services (0903) 81 4523.

SYNERTEK

Sym 1.6502 chip and keypad with memory available in 4K blocks up
to 64K. Port expansion kit, TV interface card, RAM expansion kit,
cassette and Teletype interfaces. Any Kim software, Basic interpreter,
Assembler/Editor, American, meant to be the foundation system for
every small business and hobbyist users. Available from Newbear
(0635 49223).

From £3000

From £726

From £160 plus
VAT.

TANDY CORP.

TRS-80. Min size: Level 1 4K memory; video monitor; cassette; power
supply. Max size: Level II 48K up to 350K on-line via floppy discs; line
printer; tractor feed printer and quick printer; floppy disc system.
Modern, telephone interface soon available. Basic; some business
packages. Level | aimed at the hobbyist and education market and
Level II at small business applications. Hundreds of dealers.
(Reviewed November, 1978.)

Level I — £499
Level [I] — from
£578-£4, 700

TRANSAM COMPONENTS

L4.1. 1K monitor, 2K Basic in EPROM; full graphics capability; 128
character set; power supply; cabinet; 56-key keyboard. Expandable
to 65K. Available from manufacturer (01-402 8137)

ULBRICH AUTOMATION

Powerhouse II. 16K or 32K RAM, Z-80 processor, RS232 interface;
Sin. built-in VDU; full keyboard; built-in mini cassette; real-time clock.
Software; Programmable keyboard in 16K PROM; 2K monitor
system; DOS; Extended Basic. Options: larger VDU; discs, 1 4K Basic,
Tripoh interface; X-Y graphics; IEEE interface. Compatible with all
computers and peripherals. Applications: file management, off-line
data processing and assembling capabilities. Suitable for OEMs and
expert users. Available exclusively from Powerhouse Microprocessors
Ltd. (0442) 42002, which will also manufacture it next year.

VECTOR GRAPHIC

48KB RAM. Z-80 micro; 63K bytes, mini-discs are standard. Options:
graphics. Monitor, MDOS, Basic; business packages from dealers.
Several distributors.

PRACTICAL COMPUTING January 1980

£286 kit with SKB

£2,300

Shop Window

MICRO ADS

are accepted from private readers only, pre-paid
and in writing, 20p per word, minimum charge
£2.

Financial crisis forces sale — Superboard £200,

Apple i! Plus £800. 2716 Eproms £20, 2708 £5, 2114
£3. Aylesbury 631200.

Save over £10011! Pet 8K for sale, 4 months old,
mint condition. Also full introductory programme
course. £495. Tel: Thistleton (Leics) 332.

1 brand new Apple |! Europlus complete with guaran-
tee, TV modulator all instruction manuals and several
games. Cost £882.50 best offer over £650. Please
ring 0624-4349.

Apple tl, 32K plus applesoft card, R.F. modulator. 2
months old, perfect. Not suitable for particular re-
quirement. £1000 inc. VAT. Tel: 096 279 228 (Near
London, Southampton).

SWTPC 6800, 16K, dual 5” floppy, BASIC, editor,
assembler, many extras. £850 o.n.0. 01-994 2360
evenings.

Heathkit H14 Printer, professionally assembled,
virtually brand new, £390.00 + V.A.T. Current List
£590 plus. Latest 30MH/z Dual Channel NLS Mini-
scope oscilloscope. Current Imported Price over £500
— £285 + V.A.T. Also New Motorola 02 Kit with
Manuals — offers invited. Telephone 0670-822790
(Bedlington).

Complete Computer System. Brand new CBM
32N large keyboard PET, CBM 2023 printer,
CBM 2040 dual floppy drives. Approx 70
Petsoft Program Cassettes, 12 floppy discs,
approx value software £700, hardware £2500,
offers, cash, exchange for Motorhome,
W.H.Y. Phone 0602 255155.

NASCOM with 8K expansion and B-Bug,
neatly finished in Verocase with documenta-
tion and games cassette. £275 o.n.o. Tenbury
Wells (Worcs) 810015.

PET 2001-8K only a few months old. £500
including delivery in UK. Telephone 0905
820939.

FOR SALE — brand new Commodore PET
2001-8. Price includes 20 tapes of assorted
business and games programs. £500. Uxbridge
39779 after 7p.m.

SCHOOL REGISTRATION package for RML
32K DBAS9Y. Register files, updating, lists,
age, mail. Surname christian name siblings sort
giving year, house, school rolls. £25 including
minidisc. S.A.E. details Redhead 42, Larch
Grove, Kendal.

BACKGAMMON program for 8K {or more)
PET. Includes mvoe validity check, doubling.
Program cassette plus full details £6; sample
game on cassette £1 (50p refunded if program
purchased); sae for details only. P. Compact,
118 Disraeli Road, Putney, London SW15.

FOR SALE — TI-59 programmable calculator
and PC100-C printer. Both within warranty
period. Owner upgrading kit. Price £199 the
pair. (separate sale considered). Tel. 368-2762
eves.

FOR SALE — TI-59, printer etc — £275 ono.
Write — Kishore, 386 Green Lane, Seven
Kings, liford or call evenings.

OS! SUPERBOARD SOFTWARE — Tank
Battle, Life, Zombies, TicTacToe, StarTrek,
Magic Squares, Disassembler, Biorhythms,
Magic Numbers, plus many more, £1 each
(minimum order 3). Also cassette controller —
write for details. Commissions undertaken.
Velvet Software, 26 Colesbourne Close,
Worcester.

IT has been said that it is better to leave your
PET powered up at all times. Now give it
something to do with our programme.
“Perpetual Calendar’ gives a display of day,
date, month, year and time. Runs on any Pet.
Program cassette and listing, £3. John and
Peter Douglas, 2 Glebe Park, Dumbarton G82
3HF. Telephone (0389) 64384.

117

EE i iS eS oe Diary =e

January

@7-9

@7-11

@7-18

@14

@14-18

@ 14-25

@15-18

118

TRS 80 Software. Venue: Reading. Arranged by the
Thames Valley Amateur Club, ‘The Southcote’, South-
cote Lane, Reading, Contact: Brian Quarm, tel: Camber-
ley 22186 or Brian Steer, tel: Slough 20034.

Fundamentals of computer operations. Venue: Cannock,
Staffs. Designed for trainee and junior DP staff. Gives
a basic understanding of the technical aspects, hard-
ware and software concepts, control procedures and
provides job orientation. Organised by Compower Train-
ing School, Cannock, Staffs, WS11 3HZ. Fee: £125 +
VAT. Contact: Compower Training School, Cannock,
Staffs, WS 3HZ, tel: Cannock 2511.

Database in DL/1. This database course is for users of
IMS. Venue: Cannock. Compower Training School.
Fee: £215 + VAT. Organised by Compower Training
School, Cannock, Staffs, WS11 3HZ, tel: Cannock 2511.

Cobol (advanced). Venue: Cannock. Designed for pro-
grammers with minimum of.two months’ practical ex-
perience, to enhance the student’s ability to use the
language and the machine efficiently. Fee £450 + VAT.
Organisers: Compower Training School, Cannock,
Staffs, WS113HZ, tel: Cannock 2511.

Personal Computing Course. Venue: Sunderland Poly-
technic. This ‘course consists of 10 Monday evening
sessions and is aimed at beginners who wish to take up
computing as a hobby or apply computing to their work
environment. Organiser: Faculty of Science Registrar,
Sunderland Polytechnic, tel: Sunderland 76191.

Basic systems principles for programming staff.
Venue: Cannock. This course enables programmers to
work effectively by giving them insight into the role of
the systems analyst. Fee: £255 + WAT. Organisers:
Compower Training School, Cannock, Staffs, WS11
3HZ, tel: Cannock 2511.

Management in Computer operations. Venue: Cannock.
Course for all managenient grade staff within the opera-
tions environment. All the essential aspects of management
in the operations section are covered and participative
syndicate work relates topics to practical situations. Of
particular benefit for shift leaders/managers. Fee: £480
+ VAT. Organisers: Compower Training School,
Cannock, Staffs, SW11 3HZ, tel: Cannock 2511.

Filetab TABN. Venue: Cannock. This course on Filetab
— the report generator and file maintenance package
designed by NCC — gives instruction in both the TAB
360 (IBM) and TAB-N (ICL) versions. Fee: £215 + VAT.
Organisers: Compower Training} School, Cannock,
Staffs, WS11 3HZ, tel: Cannock 2511.

Principles of 2900 operating. Venue: Cannock. Designed
for staff with at least three months’ operating experience:
enables them to play their full part in a 2900 environment.
Fee: £215 + VAT. Organisers: Compower Training
School, Cannock, Staffs, WS11 3HZ, tel: Cannock 2511.

Microcomputers in manufacturing and industrial control.
Venue: London, ICS/PCL Microprocessor Education
Centre, Holborn. Designed for manufacturing and
process control engineers and managers. Fee: £470 +
VAT. Organisers: Integrated Computer Systems UK,
Pebblecoombe, Tadworth, Surrey, KT20 7PA, tel:
(03723) 7911.

@15-18

@16

@21

@21-24

@21-
Feb 8

@22

@ 22-25

@28-31

@28-
Feb 1

Pascal: Programming in the structured language. Venue:
London. Designed for scientists, engineers, program-
mers, systems analysts and managers who are using
or plan to use Pascal for the development of software
systems. Fee: £540 + VAT. Organisers: Integrated
Computer Systems UK, Pebblecoombe, Tadworth,
Surrey, KT207PA. Tel: (03723) 79211.

Microprocessor Course. Venue: London, Willesden
College of Science and Technology. Ten-week in depth
course with attendance every Wednesday. Includes
System architecture, MPU — memory I/O, Bus structure
etc. Fee: £35. Organisers: Bill Stoddart and Dr Tony
Berk, Science Department, MPU Courses, Willesden
College of Technology, Denzil Road, London, NW10
2XD. Tel: 459-0147, ext 13.

Personal computers (how to build your own). Venue:
Wimslow. This course should be of special interest to
hobbyists who would like to built up their own com-
puter system starting from as little as £100, and to those
who have standard systems as the Pet and would like
to understand more about how they operate and make
use of their assembly languages to obtain maximum
performance. Fee: £5.20. Organisers: Course Registrar,
Wimslow Guild, | Bourne Street, Wimslow.

JCL for programmers: Venue: Cannock. Designed for
programmers who use IBM equipment to enable them
to code their own JCL. Fee: £215 + VAT. Organisers:
Compower Training School, Cannock, Staffs, WS11
3HZ. Tel: Cannock 2511.

Cobol (Basic). Venue: Cannock. Designed for trainee
programmers. Includes introduction to programming,
flowcharting, techniques, structuring, coding techniques,
documentation and standards. Fee: £645 + VAT.
Organisers: Compower Training School, Cannock,
Staffs, WS113HZ. Tel: Cannock 2511.

Microprocessor Seminar. Venue: London. Designed
for the businessman. Gives general introduction to the
Basic logic and Basic technology, and shows the use
of the microcomputer in commercial applications.
Organisers: Naomi Buhai, Birklands Management
Centre, 330 London Road, St Albans, ALi 1ED. Tel:
St Albans 66661.

Microprocessors and microcomputers. Venue: London,
ICS/PCL Microprocessor Education Centre, Holborn.
This comprehensive introduction with hands-on work-
shops is designed for engineers, scientists, systems
analysts and their managers. Organiser: Integrated
Computer Systems UK, Pebblecoombe, Tadworth,
Surrey, KT20 7PA. Tel: (03723) 79211.

JCL/Utilities for operations staff. Venue: Cannock.
Designed for operations staff including control/set up
and planning staff. Fee: £215 + VAT. Organisers: Com-
power Training School, Cannock, Staffs, WS11 3HZ.
Tel: Cannock 2511.

Computer-aided design and manufacturing. Venue:
London. Presents total overview of CAD/CAM tech-
nology, methodology and applications. Fee: £470 +
VAT. Organisers: Integrated Computer Systems UK,
Pebblecoombe, Tadworth, Surrey, KT20 7PA. Tel:
(03723) 79211.

Troubleshooting microprocessor-based systems. Venue
London, ICS/PCL Microprocessor Education Centre,
Holborn. Designed for engineers and senior technicians
involved in production testing, field service, and design
of microprocessor-based systems. Fee: £540 + VAT.
Organisers: Integrated Computer Systems UK, Pebble-
coombe, Tadworth, Surrey, KT20 7PA. Tel: (03723)
79211.

PRACTICAL COMPUTING January 1980

ws? ~

_ '
SS ne *, ‘eam
ee al 5

Multi-user Multi-tasking Multi-language
Micro-Systems
for

BUSINESS, EDUCATION or SCIENTIFIC use
from as little as £5,000
Write or phone

FQUINOX

COMPUTER SYSTEMS LTD.
KLEEMAN HOUSE
16 ANNING STREET,
NEW INN YARD,
LONDON EC2A 3HB.
01-739 2387/9. 01-729 4460

® Circle No. 226

PRACTICAL COMPUTING January 1980 119

120

BINDERS

The U.K.-designed and manufactured Novapac disk system
for Commodore's PET*, continues the integrated design
concept of your PET, with no trailing wires or bulky desk-top
modules.

The sophisticated, easy-to-use Disk Operating System
supports multiple File handling and incorporates Mainframe
operating procedures and extensive error-recovery software
for maximum Data integrity. Optional Password security for
any File or any Disk is standard. Clear documentation and a
range of Demonstration programs assist the first-time User,
while for the experienced programmer full Utilities are
supplied to aid concise program development.

A broad range of general or specialised software is available
which can be tailored to our own specification.

analog electronics

PET DISKS .... £499

(single disk)

* Novapac may be used with any available RAM plane or
with N-series PET.

* Data transfer takes place at 15,000 char/sec — effectively
1,000 times faster than cassette!

* Storage capacity is 125 K/bytes (unformatted) on 40
tracks per diskette side.

* Dual index sensors permit dual-side recording for 250 K/
bytes per diskette.

* Easy operation full-width doors prevent media damage.

* System expandable to 4 drives.

“Industry Standard IBM 3740 recording format for in-
dustry-wide media compatibility offered only by NOVA-
PAC.

“Dedicated Intel 8048 microprocessor and 1771 FDC
minimise PET software overhead.

* Local maintenance support available.

Novapac Dual-disk system complete with PDOS and Utility

disks £899 + VAT. Del. Ex. Stock.
32N — PET plus Dual disks £1,600 + VAT.
Complete system including 80 col. printer £2,200 + VAT.
3% discount for C.W.O.

47 Ridgeway Ave,
Coventry
Tel: (0203) 417761

INNOVATIVE

Y Personal

/ Games

TRS-80 SOFTWARE

Y Business ¥Y Programming Aids
Y Custom

/_ Utilities

6 Years Microprocessor Experience!

95p plus 50p postage for list and binder.

A.J.HARDING CMOLIMERX)

28 COLLINGTON AVENUE,BEXHILL-ON-SEA,E.SUSSEX.

TEL: (0424) 220391 =a
TIhiItliiiiiiiiiiiiiiiliiliiiietii litle

Our Software List is being updated so frequently now that we are supplying it pre-punched
for a ring binder. We are also supplying, without profit, a handsome ring binder which will
house the list and also has room for program instructions, notes etc. Large 18p SAE for list alone,

¢ Circle No. 228
PRACTICAL COMPUTING January 1980

A division of
CRAYWORTH (COMPUTER SERVICES) LTD.

SHOWROOM and OFFICES

34B London Road, Blackwater,
Camberley, Surrey.

Telephone: 0276 34044. Telex 858893
open Monday-Friday 9 a.m.-6 p.m.
Saturday 10 a.m.-5 p.m.

by appointment only

Personal Callers Welcome.
Please phone first if you require a personal demonstration.

Cromemco System 3

*multi-user *Mailing lists

*Fortran “finance available

“Word Processing *Cobol

“early delivery “Data-Base management
*Basic

* Assembler

Exidy Sorcerer

32K Machine with Z80 processor and 8K ROM BASIC.

128 character ASCil keyboard and superb graphics.
DOUBLE DRIVE configured MICROPOLIS DISK SYSTEM
with MDOS or CP/M 630Kb. Professional quality monitor,
various sizes up to 16’’.

Alternatively, now available, the new VIDEO-DISC UNIT
incorporating dual disc drive and screen. Printer —
optional 80 or 132 column printer. Software packages are
available, including the Word Processing EPROM PAC,

or can be written to your own specification. The system
can be expanded to suit your own applications.

PRACTICAL COMPUTING January 1980

*Sorcerer CP/M Software

CP/M operating system MAC macro assembler

SID symbolic debugger TEX text formatter.
DESPOOL simultaneous print utility.

TEXT WRITER II text formatter.

SELECTOR II multi-key database (requires CBASIC 2)
CBASIC-2 pseudo-code compiler.

DIZILOG Z-80 disassembler.

*Specially designed software need
not be expensive

We specialise in producing well designed and constructed
software with full documentation, user training and a
guarantee.

We can quote ona fixed price or time and materials basis.
We require only one third payment on commencement of
software projects, one third on delivery and one third
AFTER the guarantee period. We can then provide an
annual maintenance agreement.

Cromemeo

Cromemco Z2.

The outstanding Cromemco Z2 with fast Z-80 CPU

and 21 slot S-100 backplane. Software includes
EXTENDED BASIC, ASSEMBLER FORTRAN, COBOL,

DATA BASE MANAGEMENT and WORD PROCESSING.

Dolphin BD-80 Printer

80 column, bi-directional, the best in its price range.
Dealer enquiries invited.

PRINTERM 879 — Matrixprinter 120 cps.

OKI DP100 — 132 column 275 cps 1251 pm.
SPINWRITER — high quality printer, ideal for word
processing functions.

BURNT HILL BH720 VDU.

ELBIT DS 1920X.

MONITORS — Professional quality 9°’ & 16”’.
COMPUTER BOOKS — Awide range of micro, mini &
mainframe books. Full catalogue available.

MEDIA — Floppy discs, library cases, cassettes.

e Circle No. 229

121

U.K. — Micro Supplies —SCOT LAND. 13371-795
FLOPPY DISCS (iazozos $100 BOARDS

1041-11 315K drive + controller SD Sales 32K Ram 375 ns Assm.+tested £355
Cable + BASIC, ASSEMBLER, JADE Z80 2 mhz Assm. +tested £140

+ EDITOR only £595.00 MIKOS 15 slot Mother Board Assm.+tested £110
1015-11 315K drive — add-on £395.00 MIKOS 2 Parallel/2 Serial Assm. +tested £130
other products on application MIKOS 16K Erom (No 2708's) Assm.+tested £110
MIKOS Extender Board Assm. +tested £47

DS525-10 Pack of 10 5%in. floppy disk £29.00 MIKOS Real time clock 2 interrupt Assm. +tested £120
DSEL P.S.U. Kit+8v +16v 4A Assm.+tested £175

V.D.U.s neaeSena SOFTWARE

ADM 3A Introductory Offer CP/M for Micropolis
Hard disks 5-36 M6 POA MACRO for above

Volume discounts *special offer* TAILORED Software for all applications

eR ak CEN TRONICS| SYSTEMS

Centronics 779 £750.00 U.K. DISTRIBUTOR for
Centronics 701 £1210.00 SDS-200 (SD Sales) also HORIZON,
Centronics 703 £1894.00 CROMEMCO, DATA SYSTEM 800, 801

FULL SERVICE & BACK-UP FACILITIES AVAILABLE
Telephone for all Non-Listed items ACCESS

BARCLAYCARD
OEM & DISCOUNTS on Application

Delivery at cost — Pricés exclude VAT

TD.
tiie Osd74-795

NEWBURGH, FIFE, SCOTLAND.

® Circle No. 230

INTEGRATED SMALL BUSINESS SOFTWARE
-iISBS -

FAST AND EASY TO USE ISBS MEANS INCREASED EFFICIENCY
AND PROFITABILITY - PUT IT TO WORK FOR YOUR BUSINESS
ISBS

STOCK ORDER ENTRY toc CONTROL x.
CONTROL & INVOICING ORDER ENTRY & INVOICING 350
GENERAL ACCOUNTING 400
NAME & PAYROLL 500
ADDRESS Packages supplied on floppy disk with easy to follow
Reference Manuals — NO PREVIOUS COMPUTER |
KNOWLEDGE REQUIRED TO OPERATE. ISBS runs
on 48K Northstar Horizon, Rair Black Box or other sys-
Other software packages available include Time
Recording Systems, Finance Control and many others.
Special application software undertaken for Northstar
GENERAL & Black Box and also complete TURNKEY SYSTEMS.
PAYROLL
ACCOUNTING ' “CP/M registered trademark of Digital Research.
Costs shown exclusive of VAT.

| NAME & ADDRESS SYSTEM 250
COMPANY eres” ) tems supporting CP/M* — plus VDU and 132 col
Dealer enquiries welcome.

COMPANY PURCHASES SYSTEM 450
PURCHASES SALES printer. Complete suite or individual packages avail-
| —J —l — —J _]_ | Tf, S2 SHAFTESBURY AV. LONDON W171.

COMPANY SALES SYSTEM 450
SYSTEM SYSTEM able now and are fully supported.
————Se
01-734-ss6e

122 PRACTICAL COMPUTING January 1980

QUALITY PROGRAMS FOR PET

TARGET GOLF £8 inc

Oisr latest cassette and entirely compatible with our policy of only
publishing the very best programs. The graphics with this game
have to be seen to be-believed. The representation of your golf
swing portrayed on the PET screen is remarkable. The spacing and
rhythm of striking three keys allows this clever machine code pro-
gram to effect a variety of shots: Pulled, Faded, Sliced, Topped,
Pushed, Drawn, Hooked etc. The ball proceeding across the screen
to the target hole. A variety of holes and wind conditions are pre-
sented to the player, to which he makes his choice of club and
tvpe of swing, This is another of the very few programs, like Stud
Poker, that we, who live with computers all day long, can play
continuously without getting bored.

AIR TRAFFIC CONTROL €5 inc

Can you keep your cool? After a few minutes with this
simulation you'll see the problems Air Traffic Controllers have,
Yur screen is the radarscope and you have to give orders for
aircraft to lose or gain height or alter course to avoid collisions --
after you've requested a SQUAWK of course. And sometimes
it gets very busy up there!

DOGS CHANCE €5 inc

Reduces everyone to hysterics the first time they see it. You have
to take off in your biplane, being careful not to try and leave the
ground too soon and not leaving it too late, climb away avoiding
the anti-aircraft guns. Having congratulated yourself on this
achievement the ‘flying bombs’ suddenly appear. You must en-
deavour to shoot them down before they get you. And, well...
you haven’t a Dogs Chance! Again, truly marvellous graphics in
this machine code program.

FIVE CARD STUD POKER £8 inc

This is certainly the best Poker game we've ever seen, It should
not be confused with those where you only bet against the odds
of completing a hand. PET ACTUALLY PLAYS AGAINST
YOU and a very poker-faced, cunning game tool If you are
already a poker player then you won't be able to leave this
alone, If you don’t play yet, be warned — you'll be hooked in
minutes. The graphics are superb of course, Even we can’t leave
this one alone — and that’s saying something!

and now tntroducing.....

PAYROLL
FoR 52K PET anp CBM DISK

At last, an easy to use, efficient, straightforward Payroll Program
for the New PET and Commodore Disk. It is so ‘User Friendly’
that it almost doesn’t need a Manual. There is one of course.

Don’t let the price mislead you. We believe that this is the best
Payroll Program of its type on the market.

Look at its coverage:

* ALL Tax Codes

* ALLN.|. Codes

* Hourly, Weekly and Monthly Staff
{and mixed on the same Disk File)
3 Rates of Overtime

5 Pre-Tax Adjustments with Aipha
5 After-Tax Adjustments with Alpha
Cash Analysis

Separate Total for Cheque Payments
Can run with or without Printer
Prints Payslip and Copy side by side
Prints Totals to Date

Prints employee File Details
Suitable for most Printers (Strings)

ee @e es ew ee eee

The program has been written to our usual high standards.

FROM YOUR DEALER OR DIRECT FROM US CWO

LANDSLER SOFTWARE
29a, TOLWORTH PARK ROAD
SURBITON, SURREY KT6 7RL

Telephone: 01-399 2476/7

WE CAN! HELP
YOU WITH:

qo?
or 8
2001(32K) £715
2001(16K) £607
2001(8K) £495
PETACT: Well written business systems

covering Sales & Purchase Ledger,
Invoicing, and Stock Control:from€270

_ £675 |CBM3040 £880
inc cable

£550 | COMPU)\400K£875
THINK /800K £1095
from£essg

CBM 3022
ANADEX
TELETYPE 43

PETAID: From Stage One Computers,
disk based file handling in-hours, not
weeks — possibly the most useful
piece of software available for PET.
CBM or COMPU-THINK £140

Many more items in stock

For details of these and many more products and services; telephone:-

IAN KENDRICK ~ 051-227-3301

e Circle No. 232

PRACTICAL COMPUTING January 1980 123

MODEL 14 EPROM ERASERS | Happy Memories

21L02 450ns Pp

21L02 250ns TRS-80 16K Upgrade Kit
450ns 5
250ns £64 for keyboard unit
300ns
150ns £58.50 for expansion box
450ns

Floppy Discs by VERBATIM £21.50 box of 10
{Mini soft sectored for APPLE. PET. TRS-80 etc:)

We stock the full NASCOM range of products
Large quantity of 74LS stocked along with many

EPROM ERASER UVIAl

Features:

5 to 50 minute timer : TEXAS IC SOCKETS 8 14 16 18 20 24 28 40
¢ Safety interlocked to prevent accidental exposure Solider tail pence:10 11 12 16 17 21 27 «37

ie UV source a Wire ceoran -- 24 36 39 46 58 63 70 109
e Fast erase times (typically 20 minutes for ¢ :

5 Convenient slide-tray loading of devices Gold plated S100 edge connectors £3-25 each 3/£9-50

e Rugged construction 4.7 & 8 way DIP switches, all at 85p We keep a full range
¢ Price only £78 + VAT (Price includes delivery)

: ate 4 sth:
pe fli also available: similar to UV141 but with ener Ss ener es

Price £61.50 + VAT (Price includes delivery). = | Werve got
Use the reader enquiry service or write/telephone for y | Educationaid Gobernmi@nt
further information.

Send Cheques/ Official Orders to: orders welcome Min £10 |
a es |

GP lndustrial: Electronics Ltd. Shop open ten until six Access & Barclaycard
ardon Works, Skardon Place, ill, : inc VAT ord d
Plymouth PL4 8HA Prices inc VAT, orders below £10 add 25p p&p
Telephone Plymouth (0752) 28627 19 Bevois Valley Road, Southampton,

SERENDIPITY
SYSTEMS
SOLVE

THE
SOFTWARE
If you're puzzled by the lack of good application PUZZLE

software for micro-computers — then puzzle no longer! Great Northern Computer Services are now
the distributors for the Serendipity Systems range of packages and we are looking for dealers.
Stock Control, Ledgers, Payroll, Job Order Control, Professional Client Billing, Appointments and
many more. The Programs conform to British practice and the manuals are user-oriented;

so there is no puzzle there either.

The programs are offered in. CBASIC, Cromemco Extended BASIC and North-Star BASIC. There

are also packages for the Apple. Over 1800 packages have already been sold by more than 200
dealers and retailers. So stop puzzling and write or call today!

GREAT NORTHERN --:--: s--ice:

15 Wellington Street, Leeds LS1 4DL Telephone (0532) 450667

of wire wrapping equipment: Wrap-Strip-Unwrap tool £5-97

¢ Circle No. 235
124 PRACTICAL COMPUTING January 1980

}RAINSAM, s2usvck
PRODUCTS
TRITON 22" _| | EXPANSION MOTHERBOARD

THREE NEW EXCITING EXPANDABLE SYSTEMS 7\
DESIGNED FOR EASE OF CONSTRUCTION - )
AMD FLEXIBILITY. KITS COME Va ‘
COMPLETE WITH CASE, POWER ee

SUPPLY, FULL KEYBOARD, PCB. \

ALL COMPONENTS AVAILABLE SEPARATELY

SEE CATALOGUE.

FULL HARDWARE AND PROGRAMMING MANUAL AVAILABLE.

THE SYSTEM IS EASY TO EXPAND AND IS WELL SUPPORTED.
FEATURES 2, 2.5 OR 7K BASIC IN EPROM (SEE CATALOGUE).

TRITON. Expand your Triton simply

and easily with our new 8-slot mother-

board; complete with its own P.S.U.

takes 8 plug-in Euro cards. Plug-in 8K

RAM card and EPROM cards now

available. Kit complete with PSU + 1 Set Connderore,

8K RAM aN 8K EPROM
CARD ES “| | CARD

@SINGLE BOARD @ THREE FIRMWARE OPTIONS TRITON 8K STATIC TRITON 8K EPROM CARD LQ Y
@HOLDS UP TO 8K MEMORY @BASIC IN EPROM RAM CARD KIT USES MS 6 KIT DESIGNED TO TAKE UP T0._<@>

@ VHF OR VIDEO OUTPUT @64 GRAPHICS CHARACTERS 2114 LOW-POWER 4K KIT 82708 EPROMS (1K x8)_/Q> Oy
@ CASSETTE INTERFACE @ PLUG IN EXPANSION BOARDS STATIC RAMS ON-BOARD £97 PC8 ONLY £15 ‘ 2 ,

REGULATION MEMORY KIT LESS EPROMS £31
JUMP SELECT EPROMS (BLANK) £9

PCB ONLY £15, RAMS £5.50 vat PLUS VAT +
KIT LESS RAMS INCL ALL SKTS & COMPONENTS COMPLETE KIT VAT

Personal Computer £286 +var

BI-DIR ' our
BI-DIRECTIONAL £595 + var S100 BOARDS __s ITHACA DPS! weet
MATRIX PRINTER 8K Static RAM board (450ns) £123.75 Pascal/Z —
THE BD8O IS A LOW-COST, 80-COLUMN LINE PRINTER BK Static RAM board 250ns) 146.25 ea rd
wiTH MICROPROCESSOR CONTROL TO PROVIDE Fava ard (aM Ce eons remel ig 3 aot
EXCELLENT AVAILABILITY AND PERFORMANCE. 2708/27 16 EPROM board Gee ads Wie le F ei Eg]
@5 x7 Dot Matrix @Full ASCII Char. Set @Selt Test Rrotetype oats ore a Available bus system using DPS] /e =~. - elgg
@10 Char. perinch @10 Lines/sec Paper Advance ae bene ane ee rn, ee =88e
@6 Lines/inch @112 Char./sec @Fully Cased Disk controller board 2 pe

@400 Char. Buffer @82 Li mi K2 disk operating system
ead “Alaa ig Assemble/ZMacro Assm A We stock the full range of ITHACA products.

A
UNIQUE _ — ”
PRINT riton resident assembly
mee EDGE CONNECTORS GOLD CONTACT TRAP! = language package.

AND DOUBLE- SIDED PCB CONNECTORS Links via the L6.1 monitor and new scientific
RELIABLE lin. PRICE . PRICE basic to make Triton a stand alone development
system. Trap is an 8K package in EPROM and
resides on our EPROM card. Set of 8 x 2708
only £80 including document.

SWITCH-SELEC TABLE BAUD RATE FROM 110 TO 9,600
ON A STANDARD V24 AND RS232 INTERFACE. SEND
SAE FOR FURTHER DETAILS. IDEAL PRINTER FOR
TRITON OR ANY SYSTEM REQUIRING HIGH-SPEED, 5, .

RELIABLE HARD COPY. WE CAN SUPPLY . 5 ; . CREATE to ° MONITOR © aad
CONSUMABLES. : ul “ See catalogue for further details.

ARORA P RRA MING
STTUG AGRA ARE ECE

MEMORY AND SUPPORT CHIPS prices exciuve vat) NEW LOW PRICES

COM PONENTS 74LSXX 8292 res 3 twats 5 1M
; 300 tuasen east

tMtcBeD Peat
MISC.

SN74.SOON 18 SN7ALSS4N SN74LS138N SN74SI95AN
18 SN74LS5SN 21 SN74LS139N SN74LS196N
20° SN74LS63N 1. SN74LS145N SN74LS197N

SN74LS73N 35 SN74LS148N 175 SN74LS221N

SN74LSO4N SN74LS74N SN74LS151N ES SN7ALS240N

SN74LSOSN SN74LS75N SN74LS153N SN74LS241N

SN74LSOBN SN74iS76N SN74LS154N 1 0 SN74LS242N

SN74LSO9N SN74(S78N

SN74LS10N SN74LS83AN

SN74LS11N SN74LS85N (0 SN74LS1S7N 60 SN74LS245N

SN7T4LS12N SN74LS86N SN74LS158N SN74LS247N

SN74LS13N SN74LS9ON SN74LS160N SN74LS248N

SNT4LS14N SN74LS91N 99 SN74LS169N

SN74LS15SN 25 SN74LS92N SN74LS162N

SN74LS20N SN74LS93BN SN74LS163N

SN74LS21N SN74LS9SAN SN74LS164N

SN74LS22N ‘ SN74LS96N . SN74LS165N SN74LS386N

SN74LS26N SN74LS107N SN74LS166N SN74LS390N

SN74LS27N SN74LST09N SN74LS166N 39 SN74LS393N

SN74LS112N i SN74LS395N
SN74LS113N Ns 39 SN74LS396N
SN74LS114N SN74LS173N SN74LS273N SN74LS398N
SN74LS122N SN74LS174N 1. SN74LS279N _.79 SN74LS399N
SN74LS123N SN74LS175N 1. SN74LS280N SN74LS424N

SN74LS36N =. 29 SN74LS124N SN74LS181N SN74LS283N SN74LS445N

SN74LS40N SN74LS125N SN74LS290N SN74LS447N

SN74LS42N SN74LS293N SN74LS490N

SN74LS47N SNosLS205AN 2 20 SN74LS668N

SN74L548N k 75 SN74\S298N 220 SN74LS669N

SN74LS49N 1. SN74LS136N SN74LS194AN SN74LS324N 180 SN74LS670N

SN74LS325N
SN74LS326N
SN74LS327N
SN74LS352N
‘SN74LS353N
SN74LS365N
SN74LS366N

8ssse

M4890.
tM1489AD

RESRRSSASSSELRSENASSSRRASSESSH
BABRSF ara

Beanna——

Ses trans

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S

SN74LS373N
SN74LS374N
SN74LS375N

LM301AN-8
LM (MINI DIP}
LM308N

meee SONI ae RBRowW SU ee

BRBES se 5esesssssssssse:
8s

a als a wae en SS ee eC
MHVH ery
2RSsers

FSSRSSERESSSSSRSSE

mane
TOR

SSanmese

BESSS ono RSS S Swen
8ES883sss

9900
WAWRAP SKTS
8DIL

S888S ssssssssasssssssszSx3x
eam

AR SR Sn eee

nm
RSwom

81LS98

BSssosraetss

16 x 21144 onty £79 LM741Ch-14
MTAICN-
8 x A1N6 only 58 [uyaren-te

TRITON DOCUMENTATION HOME COMPUTING CATALOGUE

available separately as follows, prices include p &p

Triton manual — detailed circuit description and constructional If you're in town, visit our showroom in NEW

details + user documentation on ‘evel 4.1 monitor & basic i Chapel Street, next to Edgware Road tube { RAN? M SIZE CATA

L4.1 listing — listing of 1K monitor & 2K tiny basic i station. We have Tritons on display plus a \ fe lg

POM eet er ha ET dy ; comprehensive range of components and ay LED

L5.1 listing — listing of 1.5K monitor & 2.5K basic ; a aE coe eercs LATEST PRODUCTS
; accessories, specifically for personal com-

L6.1 user documentation on 7K basic interpreter k: dat 40p+ SAE

Motherboard, 8K RAM & 8K EPROM constructional details puter users. Books, mags, tapes, data, | \

User group newsletter subscription £4 per annum cables plus much more. Showroom open 6 | cauios ¥ ALL PRICES

Triton sottware — Send SAE for list of programs available tor Triton. days a week. (Half day Thurs from 1.30 pm) \ EXCLUDE VAT

TRANSAM COMPONENTS LTD.
TRAIN VW INAN = VAT ALL PRICES 12 CHAPEL STREET, LONDON, NW1
By teuh dicen! GEER EXCLUDE VAT TEL: 402 8137
e Circle No. 236
PRACTICAL COMPUTING January 1980 125

SSsssssssssessE
SSSSSSSSSRSRESESSE
eecosco
SrSfSaS

n
a
s

NEW EDITION FOR BOTH OLD & NEW ROMS

ESSENTIAL READING FOR ALL PET USERS

THE PET
REVEALED

ALMOST 260 PAGES OF SOLID INFORMATION FEATURING:

PET circuit diagrams — How to use the diagnostic routine — PET
ROM subroutines and their entry points — Programming in machine
code — Using the IEEE and User Ports — Double-density graphics —
Uncopyable programs — Page zero locations and their uses —

A TRACE program for Basic program debugging — Disabling the
keyboard and/or the Stop key — Adding a repeat key — Line
re-numbering — Auto line erasing — Making the PET write its own
programs — Printer interfaces — Adding new commands to

Basic — Interrupts and multiprocessing.

Plus many more fascinating facts about the PET.

€ commodore APPROVED PUBLICATION

Send cheque for £10.00 made payable to Computerbits Ltd.
For details of new edition availability contact

COMPUTERBITS LTD

PO BOX 13, YEOVIL, SOMERSET. TEL. YEOVIL 26522

@ Circle No. 237
126 PRACTICAL COMPUTING January 1980

Practical Computing Back Issues

If you are interested in microcomputers you will want
to read the Practical Computing reviews of the
machines in which you are interested. Each month
Practical Computing cames at least one hands-on test
of a popular microcomputer for use in business, the
home, schools and colleges. Each review contains the
kind of information you need -technica! data and
unbiased cntical comment on the strengths and
weaknesses of each system.

Each issue is packed with essential reading on
microcomputers, including all our regular monthly
features: Book and cassette reviews; Glossary of
computer terminology; Computabits; Pet Corner
(February onwards); Apple Pie (May onwards); Tandy
Forum (March onwards); senalised Illustrating Basic
(October 1978 onwards).

All this makes Practical Computing the invaluable
source for the whys, wherefores, hows, ifs and buts of

November 1978
Review: Tandy TRS-80 Projects for KIM.
Pet goes to school; VAT accounting
complete program Part 2; Complete
@ program — Mastermind; Software
1cs Basic compiler review

December 1978

Review: Research Machines 3802.
Choosirg your first computer; ITT inter-
view; Complete games programs —
Battleships. Racing Cars and Monsters;
A microcomputerised reservation system

January 1979

Review: Nascom |. Convert an IBM
typewriter into a terminal Part I. In-car
computing — Pet in the Panther Deville
Report from the Los Angeles Computer
Faire; Pascal v. Basic.

February 1979

Reviews: Cromemco Z-2D. Low-cost
peripherals; Systems for estate agents

and doctors; A £1000 payroll system; IBM
typewriter conversion Part 2; Complete
game program — Warlock Warren

March 1979

Review: Single-board computers for less
than £50 Low-cost stock-control systems;
TBM typewriter conversion Part 3. New
monthly column — Tandy Forum. Complete
game program — NIM.

April 1979

Review: Norih Star Horizon Business
accounting systems. Apole I] design story
Part I; Computerised school meals;
Finance for school computing; Build your
own frequency meter; Star Trek game

microcomputing.
Practical
Computing

We review:
Compucoler il

pius
Ohio Superboerd

june 1979

Reviews: Compucolor Il. Ohio Super-
board II Low-cost word-processing;
Computing in a pharmacy; Designing 4
smal! business application Part 1;
Computer v. Brain; Zombie game

May 1979

Reviews: Exidy Sorcerer, Science of
Cambridge Mk 14. Printers for less than
£1000; Order processing/invoicing
packages; Retire with your computer
Apple II design story Part 2: Slalom game.

Practical
| bee <4

Chumeing your
firmt computer-
Cogn pate geet

ots.
July 1979

Reviews: AJM-65, SOL-20 Choosing your
first computer; Interfacing Pet with a
maintrame; Nascom story; Designing a

smal! business application Part 2;

Biorhythms program

actical |

August 1979

Reviews: Pet II KIM, Pros and Cost of
PASCAL Microcomputer user groups
Designing a small business application
Part 3; Interfacing Pet with a mainframe
Part 2; Life game program

your
joystick

‘teaching

October 1979

Reviews: Disc systems for Pet, Appie II
and Tandy; Build an electronic score-
board; Inside Speak & Spell;
Introduction to LISP; Inside Prestel.

September 1979

Reviews: Powerhouse 2, Acord. Anadex
and Heathkit printers Artificial intell-

igence; Build your own joystock; Computer
scene in the North-West; Mathematics on

8 Pet; Self-teaching games program.

Faalt diagnosis

Review
Rafr Black Box

Programmer
of the Year

November 1879

Reviews: Rair Black Box and TECS
Teletext computer; Computers for the
radio amateur; Learning programs;
The self-testing chip; Financial
modelling

Computing

Artificial
Intelligence
Cell Scanning

Eurapple v. ITT
2020

December 1979

Reviews: Transam Triton. Eurapple and ITT
2020. Corvus hard disc for Apple II. How to
set up Computer studies in schools. Tips for
Sorceror users, File handling techniques.

Only the above issues are stil] available. Fill in the coupon opposite and return it with your remittance to Practical Computing, General Sales Dept, Room CP34,
Dorset House, Stamford Street, London SE] SLU

PRACTICAL COMPUTING January 1980

127

PADMEDE
COMPUTER
SERVICES

VISICALC... £100
Already successful in U.S.A.
this software should be useful
to Engineers and Accountants

alike; it will be particularly
attractive to business executives
for FINANCIAL MODELLING

IEEE-488 INTERFACE CARD £216

Impact Matrix Printer £675

Simple! Quiet! Reliable!
12 characters per inch = 96 ch’s per line
at a print speed of 140 c.p.s.

Software developed and installed —
Incomplete Record Accounting £450
Time and Cost Recording £300
Job Costing £300
Order Processing £250
Sales Ledger £300
Purchase Ledger £300
Selective Name/Address Reporting £150

Enquiries for the above software
from Apple Dealers welcomed: —

Please quote P/12/ when ordering: —

PADMEDE COMPUTER SERVICES
112/116 HIGH STREET,
ODIHAM, NR. BASINGSTOKE, HANTS.
TEL: ODIHAM (025-671) 2434

COMPUTER PRODUCTS

NOW A NASCOM DISTRIBUTOR IN YORKSHIRE
Full range of Nascom Products available.
We are Nascom service and repair specialists order with confidence.
Free for a limited period with Nascom 2. 16K memory board, mini mother board
and 2 edge connectors. This is 8K more memory than specified and leaves 28K of
free space.
Unbelievable Nascom 1 now only €125.00 or £140.00 ready built and tested.

Upgrade your Nascom 1 to Nascom 2.

By using our specially designed contro! key pad this enables you to run Nas-sys
on Nascom 1. Gain on screen edit and cursor movement. The power of Nas-sys.
Kit only £21.50. Nas-sys £25.00.

A hexadecimal keypad for Nascom 1 & 2. Specially designed for your Nascom
by us. This is an essential for entry of machine code listings. New fine, space
and back space are duplicated for convenience, £29.50 complete kit.

Control and hexadecimal key pads combined for Nascom 1 £36.50 complete
kit. The above key pads require no modification at all to your Nascom.

Port Probe, A simple but essential device for Nascom 1 or 2. Allows monitoring
of the port output on L.E.D. indicators, input words can be set up with L.E.D.
indication interrupts can be tested manually or by using the variable clock pro-
vided, this also allows real timing for games £10.60 complete kit.

Dual monitor board. This kit allows switching between 2 monitors on Nascom 1
40

Chess for Nascom. A powerful chess programme which requires our graphics
options. This must be the best chess graphics available, £15.00 on cassette, ask

for details.

Nascom 1 £125.00 kit or built £145.00
Nascom 2

Power Supply Unit
Nascom 1 Buffer Board

8K Ram Board

16K Ram Board

32K Ram Board

Nascom 1 Graphics
Nascom 2 Graphics Rom
Bits & P.C.s Data Cassettes
Price for 10 C12

Please check with us for your
Nascom requirements,

Add 15% VAT to all our prices,
Barclaycard and Access phone your
order. Personal demonstrations by
appointment. Please send S.A.E.
for any details.

BITS & P.C.s

18 Rye Garth

Wetherby, West Yorkshire

LS 22 4UL

Tol: (0937) 63744 9a.m.to7p.m.

e Circle No. 239

Does your computer speak to you?
“WEHL IHT KAAN DOO WIHTH MEE!’

Features
@ Single PCB plugs directly
into an SWPTc 6800 bus.

@9 parameter vocal tract
model.

@ Realtime software
converts any stored
phonetic code to speech.

@ Computer Games.

@ External input for special
musical effects.

@ Adds speech output to
existing BASIC programs.

Microspeech package

@ Speech synthesizer board
(assembled & tested).

@ MSP2 Software on floppy
disc or cassette.

@ Hardware & Software
manual.

@ Speaking BASIC software
option.

TIM ORR DESIGN
CONSULTANT
55 Drive Mansions,
Fulham Road,
London, SW6

Make your computer

talk

Just by entering phonetic
text (as in the sentence at
the top of the page).
Microspeech with the
MSP2 software can make
your computer speak.
MSP2 uses only 4K of
memory. Every extra 1K
of buffer space can store
90 seconds of speech.

SU
“

>
—

it speaks for itself

COSTRONICS
ELECTRONICS
13 Pield Heath
Avenue, Hillingdon,
Middlesex

e Circle No. 238 e Circle No. 240
128 PRACTICAL COMPUTING January 1980

BUY

nascom-

NOW AND GET A FREE
16K RAM BOARD

The tack of availability of the MK4118 RAMs has
seriously delayed the launch of the Nascom 2, so
we have decided to relaunch the product with an
offer few will be able to refuse.

The Nascom 2 will be supplied without the optional
user 4118s. Instead, we will supply a 16K dynamic
RAM board and the interconnect for the NASBUS —
absolutely FREE. This board allows further expansion
to 32K. Also, when the 4118s become available,
customers taking advantage of this offer can have

the 8K for just £80 (plus VAT).

Meanwhile, the empty sockets on the Nascom 2 can
be filled with 2708 EPROMs allowing dedicated usage,
now with 16, or 32K of extra RAM. All the other
features of the Nascom 2 are available and these include :

MICROPROCESSOR
Z80A 8 bit CPU which will run at 4MHz but is selectable between
2/4 MHz.
HARDWARE

12” x 8” PCB through hole plated, masked and screen printed. All
bus lines are fully buffered on-board. PSU: +12v, -+5v, ~12v,—S5v.

MEMORY

@ 2K Monitor-NAS SYS 1(2K ROM) @1K Workspace/User RAM
@ 1K Video RAM @ 8K Microsoft BASIC (MK 36000 ROM)

INTERFACES

New 57-key Licon solid state keyboard. Monitor/domestic TV

PLUS
VAT

The Nascom 2 makes extensive use of ROMs for on-board
decoding. This reduces the chip count and allows easy changes for
specialised industrial use of the board. On-board link options
allow reset contro! to be reassigned to an address other than zero.

The 1K video RAM drives a 2K ROM character generator

On-board UART provides serial handling for Kansas City cassette
interface (300/1200 baud) or the RS232/20mA teletype interface.
Totally uncommitted PIO giving 16 programmable I/O lines.

providing the standard ASCII characters with additions — 128
characters in all. There is also a socket for an optional graphics
ROM on-board.

Be NASCOM UK DISTRIBUTORS EEE — FSS Se Se eee eee

To:Nascom Microcomputers Ltd.,

ADDACOMPUTERS TARGETELECTRONICS ELECTROVALUELTD LOCK DISTRIBUTION a 92 a. d Street Giesham Bucks a
Ealing,London W5. Bristol. Manchester M19. Oldham,Lancs. a ’ ’ . |
Tel:01-5795845 _ Tel:0272 421196 Tel:061-4324945 Tel:061-6520431 al Tel:02405 75155. NM/PC/5 a
BITS & P.C.s THECAMERACENTRE ELEYELECTRONICS MICRODIGITAL ;
Wetherby, Barrow-in-Furness. Glenfield, Leics. Liverpool L2. B Please send ae Nascom 2 kits ia
Tel:093762592 - Tel:0229 20473 Tel:0533871522 Tel:051-227 2535 i (complete with construction article and |
BUSINESS & LEISURE COMP SHOP HAPPY MEMORIES pHOTOACOUSTICS ff extensive software manualforthe monitorand Jj
MICROCOMPUTERS NewBarnet,Herts. | Southampton. Watford, Herts.
Paver, Tel-01.441 2922 Tel:0703 39267 var raeaaeoee B BASIC) at £295 plus VAT plus £1.50 p&p. o
Tel:0926512127 COMPUTERMANIA HENRY’'S RADIO B And 3A PSUs at £29.50 plus VAT a

‘ PIPS COMPUTER 5
THE BYTE SHOP Great Milton,Oxon. — London W2. SERVICES B plus £1.00 p&p. And optional a
{lford,Essex. Tel:Great Milton 729 Tel:01-723 1008 Whitley Bay, 5 graphics ROMs at £15.00 plus VAT. a
Tel:01-554 2177 C. C. ELECTRONICS ER EATS Tel:0632 482359 a Fj
London W1. Torquay. COMPONE
Tel:01-6360647 —‘ Tel:0803 22699 Amersham,Bucks. P ie COMPUTERS | Name a il
COMPUTERLAND DATRONMICROCENTRE Tel:0240322307 —_— Belfast. A 5
Nottingham. Sheffield. A& GKNIGHT STRATHAND Address
Tel:0602 40576 Tel:0742 585490 Aberdeen Glasgow. | i
Manchester 1. ELECTRONICSERVICES 1 e!:0224 630526 Tel:041-552 6731 al al
Tel:061-2364737 Sheffield. ia 4]
Birmingham. Tel:0742 668767 Aetessi
Tel:021-6227149 ELECTROVALUE LTD D barckycardNo! Oi
Glasgow. Egham, Surrey. i SS eee
Tel:041-2217409 Tel:078433603 Nascom Microcomputers (Ey A ss ee ed

BARCELLOS Ltd

Kimberley House, Vaughan Way,
, Leicester. Tel. 0533-26584

All your microcomputer requirements can be
bought with confidence by mail order from
MICRODIGITAL, one of the largest and longest
established computer stores.

Most orders are despatched same day as
receipt, if not a note explaining what the supply
situation is. If we cannot supply within 30 days we
will, on request, make an immediate cash refund.

Access and Barclaycard orders are welcome
either in writing or over the phone. Your account
will not be charged until the goods are despatched.

Official orders of over £10 are also welcome.
With norma! 30 days trade credit extended to bona
fide commercial and government organisations.

If you do not have our brochures, write or
phone today for free copies by return.

/M\\CRODIGITAL,

MICRODIGITAL LIMITED
FREEPOST (No stamp required) LIVERPOOL L2 2AB
= TEL: 051-236 0707 (MAIL ORDER 24 HOURS ADAY) ff rs i
TEL: 051-227 2535

Four only

Word Processors
as new for
immediate delivery

Price £1500.00 each

Rental terms £25 per week*
Minimum rental period 12 weeks

FULL SERVICE AVAILABLE THROUGHOUT
EAST MIDLANDS AREA

*Rental price includes service in East Midlands

Phone or write
for details
e Circle No. 242 ¢ Circle No. 243

REAL-TIME EXPANSION
SPECTRUM bac
ANALYZER

£340

break-
through

You can now buy, for about one-sixth the
price of current products, a third-octave

spectrum analyzer with more features and

capabillties than were previously available

at any price. What's the catch? ie 3 2 5
If you don't already own a Commodore

PET computer (or, soon, a Radio i

Shack TRS-80 or Apple), you'll rae items ao
have to get one. This will raise eseenan
the price to somewhat under demonstrated at
one-half the price of com- our London showroom
peting products, but of course ite
you'll aiso have a COMPUTER! Orders accepted by

The THS 224 REAL-TIME FREQUENCY ANALYZER

mail, phone or in person.
comprises a single circuit board which installs inside the PET. PETS 8k *P a
This board contains a set of 31 third-octave filters (20 Hz to 20 kHz),

Prices exclude VAT. Send or phone

defectors, an analog-to-digital converter, a 1K Read Only Memory from £ 4 9 5 for further details and brochure.
containing machine language routines which allows the PET processor fo Access, Barclaycard, Ss
to interface with the Analyzer, andthe peripheral circuitry necessary ——-EEISATMDEMARKOF and Trustcard accepted. Caden) =m

to transfer analog data into the PET memory. The simplest BASIC
program required fo turn the PET into an analyzer is only
three statements long! Much longer programs can be
written to allow complete user interaction with the analyzer,
including many new forms of statistical signal processing,
curve weighting, voice recognition etc.

{ UK Distributors

Feldon Audio Ltd.,

126 Great Portiand Street. London W: Tel oe -580 4314. Telex: London 28668.

@ Circle No. 245
130 PRACTICAL COMPUTING January 1980

WHY BUY A
MICRO-COMPUTER FROM

PETAL HESS seavicine cro.

BECAUSE

1) Established company trading since 1971 7) We can arrange finance

2) Electronic servicing is our speciality 8) We offer, after the three-month warranty, a
service contract from £69.50

3) We have in-house programmers/systems

analysts 9) You benefit from our experience of having
4) We have our own service engineers sold over 450 micro-computers to industrial,
: educational and business, personal users.
5) We will demonstrate the PET at your 10) We specialise in programs and interfaces for
ai weighing applications for average weight
6) We can customise the PET to your control and counting etc.

requirements

All ‘PETS’ sold with a Basic Tutorial Tape

8K £550.00 + VAT
16K £675.00 + VAT
32K £795.00 + VAT

New Large
Keyboard ‘PETS’
Now in Stock

In our showroom we sell
Books, Programs, etc.

Also available:
24K Memory Expansion Boards (disk-compatible), only £320 + VAT
PET-compatible : dual floppy disk unit with advanced operating system, only £840 + VAT
Large Extension Keyboard for the PET £89.50 + VAT
Telephone for complete system prices : Wide Range of Printers Available

If you require any more information or demonstration regarding the PET 2001/8 or any associated
equipment, programs, etc., please contact Mr. P.J.A. Watts or Mr. D.W. Randall at:

Shop at:

PETALECT ELECTRONIC SERVICES LTD PETALECT
33/35 Portugal Road, Chertsey Road,
Woking, Woking,
Surrey. Surrey.

Tel. Woking 69032/68497 Tel. Woking 21776/23637

¢ Circle No. 246

PRACTICAL COMPUTING January 1980 131

You're invited to come and see the

USINESS SYSTEMS

at your official

commopore CX ana PetSott
dealers in... <Loun est London

Combine the NEW large keyboard PET with the

East Sheen

London SW 14

Tel. 01-876 6609

ACT PETSOFT Professional Disk Systems and
Software, and the result is a powerful business
tool. If your application includes Sales Ledger,
invoicing, Purchase Ledger, Payroll or Stock
Control, then come and see us without delay.

MICRO COMPUTER CENTRE

Virage Holding Co. Ltd.
314 Upper Richmond Road West

¢ Circle No. 247

CRYSTAL ELECTRONICS
CC ELECTRONICS

NEwI! XTAL BASIC 2.2

HAS TO BE THE BEST YET FOR YOUR
NASCOM 10R2

Ail the best features of other 8K floating-
point BASICS

PLUS:

EXTRA COMMANDS/FUNCTIONS—CHIN,
KBD, CMD§ ON ERR GOTO

% — Add up to 64 reserved words of your
choosing — NOW put your own disc, tape,
control, graphic commands, etc. for, the
ULTIMATE in BASIC flexibility!

FULLY upward compatible with version 2.1
(see earlier ads).

EXISTING 2.1 users — Return your original
tape (less manual) with 50p p&p and we
will update it FREE of chargel

PRICE: STILL ONLY £35 + VAT

Shop open 0930-1730 except Wed. & Sun.
40 Magdalene Road, Torquay, Devon, England. Tei: 0803 22699

Access and Barclaycard welcome. = | |

132

GRAPHICS BOARD ‘phone for details.

By local designer — as shown in
COMPUTING TODAY (DEC).

2 versions — 32 or 128 programmable shapes
Resolution 192 x 128 — for minimum or
expanded system.

CREED PRINTER INTERFACE

For NASCOM or APPLE — lowest cost
hard copy!

Complete kit of parts (with Software) £18
+ VAT.

16-CHANNEL RELAY BOARD

Now in stock for NASCOM 1/2. For £49.95
+ VAT.

16 switched (isolated) channels for many
control applications. This kit will greatly
increase the flexibility of your NASCOM.

NOW IN STOCK —

FOGT Dr 2 2295 + var

Includes free 16K RAM board, making this
the cheapest 16K + machine on the market.
Also the new NASCOM PRINTER at the
SUPER price of £325 + VAT — Serial
operation, suits most micros.

PRACTICAL COMPUTING January 1980

computer

—— Sales and Service
APPLE II. Now from £750 + VAT

Eighteen months of experience in APPLE
hardware and software makes us the leaders
in the West Country.

New PASCAL system £296 + VAT.
A & D CONVERTOR BOARD £175 + VAT.

B & W monitors 9’ £132 + VAT
12" £210 + VAT

plus fuil variety of printers, cards, memory, etc.

LL RANKS)
or art

For speed, power, storage, high print rate
and compactness. Probably the world’s first
self-contained desk-top computer. One
megabyte at your fingertips. Add-on to 20
megabytes, multi-tasking, etc.

£8500 starts you into the BIG league of

business computing.

® Circle No. 248

COMPUTERS
AND
COMPONENTS

SNCROSVSVEMNS 80

A Conference and Exhibition to
helo you come to terms with the
second Industrial Revolution ©
sh
at the WEMBLEY CONFERENCE CENTRE

JANUARY 30 -FEBRUARY 1 from 10 am each day

CONFERENCE SESSIONS enable you to share the
experience of experts in the microtechnology field.

A BUYERS’ FORUM helps you to establish
effective criteria for selection of goods and
services.

A PROFESSIONAL DEVELOPMENT SEMINAR
introduces managers to the use of microprocessors
in business and industry.

AN EXHIBITION where you can talk personally

with the suppliers of microtechnology products
and services.

Admission to the exhibition is free. You may book
in on the spot for conference sessions, or obtain
further details of fees and a booking form from:

PNNCR@SVSIEMNS

CON PelkeNiCe Room 821, Dorset House, Stamford Street, London, SE19LU.

e Circle No. 249

PRACTICAL COMPUTING January 1980 133

The new all-British-designed single-board

MICROCOMPUTER

SEMEL-ABACUS
IN KIT FORM

Supplied with 16K of RAM
Uses the powerful Z-80 Microprocessor
Space for up to 32K RAM on board

8K Full Basic

VDU Memory Mapped

You Can See
The ABACUS

i At Bread
64 Characters by 16 Lines ot Gea

Tape Interface
Single-Board Construction
RS232 Printer Interface
Plugs into a standard TV set

Royal Horticultural

Halls, London SW1

4th-8th December
Stand G7

‘Full alphanumeric Characters plus 64 User-

Definable Graphics
Stabilised power supply

Camere SRO RS i ’
oii aa.

nencui — wi = ] 4
RALIETS 3) apedl i
cence! “Sree, PT nT

TECS: FEATURES

*VIEWDATA AND PRESTEL
DATABASE ACCESS

* FULLY EXPANDABLE COM-

PUTER SYSTEM

* MEMORY-MAPPED TV DIS-
PLAY RAM

*24ROW x 40 CHARACTER,
ALPHANUMERICS AND
GRAPHICS (226 Individual sym-
bols} DISPLAYED IN SIX COL-
OURS PLUS B&W, ON UNMOD-
IFIED COLOUR T.V.

* EXPANSION TO FULL 64K
MEMORY

* SUPPORTS BOTH 5%” and 8”
FLOPPY DISCS

* RS232 PORT AS STANDARD
*3K TECS MINI-BASIC,

INTEGER VERSION WITH COL-
OUR DISPLAY

* 8K TECS BASIC; FULL FLOAT-
ING POINT VERSION
*TECSBUG: POWERFUL
MACHINE CODE MONITOR
*TECSOFT RANGE OF
SOFTWARE TO EXPLOIT THE
FULL POTENTIAL OF THE TECS
SYSTEM

*FULL FACILITY TELETEXT
RECEPTION (CEEFAX, ORACLE)
*KANSAS CITY STANDARD
CASSETTE INTERFACE

*FULL DOCUMENTATION
PACK

* ALL SYSTEMS CAN BE
EXPANDED LATER;

OPTIONAL

* Colour Graphics

* Expansion board to full 64K Memory
* Analogue Interface

SYSTEM Tl TELETEXT, 3K BASIC KIT BUILT
4K USER RAM £895 £1175

SYSTEM T2 TELETEXT, MONITOR, £1115 1405
8K BASIC, 4K USER RAM

SYSTEM T2a AS T2 but +16K RAM £1335 £1635

SYSTEM T2b AS T2 but +32K £1435 £1735

SYSTEM T2c AS T2 but +48K £1535 £1835

SYSTEM T4 ‘PRESTEL SYSTEM’ NIA £1955
TELETEXT, PRESTEL, 4K RAM, 3K BASIC

STRUTT

ELECTRICAL AND MECHANICAL ENGINEERING LTD.
3c Barley Market St., Tavistock, Devon PL19 05F

Tet: Tavistock (0822) 5439 Telex: 45263

(KITS AVAILABLE DIRECT FROM TECHNALOGICS ONLY.) PLEASE SEND FOR FURTHER

DETAILS (LARGE S.A.E., 13P STAMP PLEASE) OR ORDER NOW (SPECIFY RACK OR

TABLETOP VERSION) FROM YOUR DEALER OR IN CASE OF DIFFICULTY DIRECT FROM
TECS SALES DEPT.,

TECHNALOGICS LTD.,

8 EGERTON STREET, LIVERPOOL L8 7LY Tel:
051-724 2695

ALL ORDERS DEALT WITH IN STRICT
ROTATION, CARRIAGE AND INSUR-
ANCE PAID. ALL PRICES SUBJECT TO

15% VAT.

¢ Circle No. 250

@ Circle No, 251

COMPLETE COMPUTER SYSTEMS (CCS)

- CCS Microsales

LEARN “BASIC” witha £50
Voucher towards the cost of

a“ BASIC” course when you buy
a micro from us

ABC80

APPLE

We Know

SEEING IS BELIEVING

and invite you to come and see the ABC80 and others at our-new
Letchworth shop (Open Nov.) Just clip the coupon and sent it to:
CCS MICROHIRE/MICROSALES
FREEPOST (7 The Arcade)
Letchworth, Herts.

134

Z80A based. Fastest in this price range. Fantastic ‘BASIC’

in 16K ROM plus Assemblers and FORTRAN (disc based) and
over 35 Industrial 1/O and memory boards.

48K Disc based WORD PROCESSING Turnkey System inc.
{BM Printer only £1990 (ex. VAT) also 12 extra boards from
CCS as options to all the usual Apple Boards.

PET Our own boxed $100 interface so you can choose from the
200+ index of S100 boards and use them with your PET.

All sorts of S100 goodies available on order at costs which
SORCERER make it better than the hassel of getting them on your own.

CCS Microhire

Still the Leading Microcomputer Hire
Company with the best range of
equipment:

PET (8K) now £4.20/day*

APPLE (16K) now £5.70/day*

Apple Il; PET; Exidy Sorcerer; SEED
System One/MSI 6800; NASCOM/
MICROS; Research Machines 380Z
and Tandy TRS-80.

Over 500 million Bytes (half mega-
bytes memory) available for hire in
units from 4K to 48K.

Send for our NEW PRICE LIST giving
the most attractive prices yet.

* four day rates

CCS MICROHIRE
FREEPOST (7, The Arcade}
LETCHWORTH, HERTS SG64YA

| would like to come and see the ABC80;

PET; APPLE.

Please call me back to arrange an
| appointment.

® Circle No. 252 ® Circle No. 253
PRACTICAL COMPUTING January 1980

Start Computing For Just £99.95 With An
8085-Based Professional Computer Kit —

Explorer/85

100% compatible with all 8080A and
8085 software & development tools!

No matter what your future computing plans may be.
Level "A" — at £99.95 — is your starting point.

Starting at just £99.95 for a Level “A” operating system, you
can now build the exact computer you want. Explorer/85 can
be your beginner's systems, OEM controller, or {BM-formatted
&’ disk small business system... yet you're never forced to
Spend @ penny for a component or feature you don’t want and
you can expand in small, affordable steps!

Now, just for £99.95, you can own the first level of a fully
expandable computer with professional capabilities — a com-
puter which features the advanced Intel 8085 cpu, thereby
giving you immediate access to all software and development
tools that exist for both the 8085 and its 8080A predecessor
(they are 100% software compatible} — a computer which
features onboard S-100 bus expansion — plus Instant conver-
sion to mass storage disk memory with either 5%’ diskettes or
standard IBM-formatted 8" disks.

For just £99.95 {plus the cost of a power supply, keyboard/
terminal and RF modulator, if you don’t have them already),
Explorer/85 tets you begin computing ona significant level . . .
applying the principles discussed in leading computer maga-
zines .. . developing “stage of the art’ computer solutions for
both the industrial and feisure environment.

Level “A” Specifications

Explorer/85’s Level A” system features the advanced Intel
8085 cpu, an 8355 ROM with 2k deluxe monitor/operating

ELF Il

THAT EXPANDS

ELF Il
BOARD WITH VIDEO OUTPUT

you how to use them.

THE TRIED AND TESTED
MINICOMPUTER

£79.95

FEATURING THE RCA COSMAC 1802 cpu + VAT
STOP reading about computers and get your “hands on” an ELF 11 and
Tom Pitman’s short course. ELF 11 demonstrates al the 91 commands
which an RCA 1802 can execute, and the short course speedily instructs

system, and an 8155 ROM-1/O — all on a single motherboard
with room for RAM/ROM/PROM/EPROM and S-100 ex-
pansion, p/us generous prototyping space.

{Level “A’’ makes a perfect OEM controller for Industrial
applications and is available in a special Hex Version which
can be programmed using
the Netronics Hex Keypad/
Display).

PC Board: glass epoxy, plated
through holes with solder mask

WO: provisions for 25-pin
D825) connector for terminal
serial 1/0, which can also sup-
port a paper tape reader
e " . . provision for 24-pin DIP
biests, or industrial con- socket for hex keyboard/dis-
troller use. play . . . cassette tape recorder in-
put... cassette tape recorder output . . . cassette tape control
output . . . speaker output. . . LED output indicator on SOD
(serial output) line . . . printer interface (less drivers) . . . total of
four &-bit plus one & bit 1/0 ports @ Crystal Frequency: 6.144
MHz @ Control Switches: reset and user (RST 7.5) Interrupt
. . . additional provisions for RST 5.5, 6.5 and TRAP
interrupts onboard @ Counter/Timer: programmable, 14-bit
binary @ System RAM: 256 bytes located at F800, ideal for
smaller systems and for use as an isolated stack area in
expanded systems . .. RAM expandable to 64k via S-100 bus
or 4K on motherboard.

System Monitor (Terminal Version): 2k bytes of deluxe
system monitor ROM located at F000 leaving 0000 free for user
RAM/ROM. Features include tape load with labeling . . . tape
dump with labeling . . . examine/change contents of memory

. insert data . . . warm start . . . examine and change all
registers . . . single step with register display at each break
point, a debugging/training feature . go to execution
address . . . move blocks of memory from one location to
another . . . fill blocks of memory with a constant. . . display
blocks of memory . . . automatic baud rate selection
variable display line length control (1-255 characters/line) . . .
channelized 1/0 monitor routine With 8-bit paralle! output for
high speed printer . . . serial console in and console out
channel so that monitor can communicate with I/O ports.

System Monitor (Hex Version): Tape load with labeling . . .
tape dump with labeling . examine/change contents of
memory .,. . insert data. . . warm start . . . examine and
change all registers . . . single step with register display at each
break point. . . go to execution address. Level “A"’ in the
Hex Version makes a perfect controller for industrial applica-
tions and can be programmed ysing the Netronics Hex
Keypad /Display.

Level "A" at £99.95 is a
complete operating system,
perfect for beginners, hob-

Hex Keypad/Display Specifications
£58.00

Calculator type keypad with 24 system defined and 16 user
defined keys. 6 digit calculator type display which displays full
address plus data as well as register and status information.

Level’’B’’ Specifications £42.00

Level “B” provides the S-100 signals plus buffers/drivers to
support up to six §-100 bus boards and Includes: address
decoding for onboard 4k RAM expansion select-able in 4k
blocks . . . address decoding for onboard 8k EPROM expan-
sion selectable in 8k blocks . . . address and data bus drivers for
onboard expansion . . . wait state generator (jumper select-
able), to allow the use of slower memories . . . two separate.
5 volt regulators.

Level “C”
Specifications

Level ‘‘C’’ expands Explorer's
motherboard with a card cage,
allowing you to plus up to six
S-100 cards directly Into the F 2 ‘
motherboard. Both cage and :

cards ae neatly contained inside Ere OLS ee ae vee
Explorer's deluxe steel cabinet. care Caer Bhat
Level 'C” includes a sheet metal superstructure, a 5-card gold
plated S-100 extension PC board which plugs into the mother-
board. Just add required number of S-100 connectors.

Level’D’’ Specifications £58.75

Level ''D” provides 4k or RAM, power supply regulations,
filtering decoupling components and sockets to expand your
Explorer/85 memory to 4k (plus the original 256 bytes located
in the 8155A). The static RAM can be located anywhere from
0000 to EFFF in 4k blocks.

Level’’E’’ Specifications £5.00

Level E” adds sockets for 8k of EPROM to use the popular
Intel 2716 or the TI 2516. It Includes all sockets, power supply
regulator, heat sink, filtering and decoupling components.
Sockets may also be used for soon to be available RAM IC's
{allowing for up to 12k of onboard RAM).

SYSTEM

TO MEET
YOUR NEEDS

ulator), £120.50.

85, £33.60.

O Deluxe Stee! Cabinet for ASCII
Keyboard/ Terminal, £16.00.
O Deluxe Stee! Cabinet for Explorer/

EXPLORER/85 PERIPHERALS

© ASCil Keyboard/Computer Ter-
minal Kit (features a full 128 character
set, upper & lower case, full cursor
control, 75 ohm video output con-
vertible to baudot output, selectable
baud rate, RS232-C or 20 ma, 1/0, 32,
or 64 character by 16 line formats, and
can be used with either a CRT monitor
or a TV set (if you have an RF mod-

O RF Modulator Kit (allows you to
use your TV set as a monitor), £2.78.

O Intel 8085 cpu User's Manual,
£6.00 inc VAT).

O 8k Microsoft BASIC in ROM Kit
(requires Levels “B" "'D' and "‘E"),
£82.00.

EXPLORER/85 INTRODUCTORY OFFER
BUY LEVELS A,B,D PLUS VIDEO TERMINAL
FOR ONLY £298 + VAT

NEWTRONICS KEYBOARD TERMINAL

The Newtronics Keyboard Terminal is a low cost stand alone Video Terminal that operates

quietly and maintenance free. It will allow you to display one a monitor 16 lines of 64 char-

acters of 16 lines of 32 characters on a modified TV (RF Modulator required).

The characters can be any of the 96 ASC 11 elphanumerics and any of the 32 special char-
acters, in addition to upper lower case capabilityit has scroll-up features and full X-Y
cursor control. Ail that is required from your microcomputer is 300 baud RS232-C or 20ma
loop sefial data plus a power source of 8v DC and 6 3v AC. The steel cabinet is finished
in IBM Blue-Black. And if that is not enough the price is only £135.50 + VAT as a Kit,

or £175 + VAT assembled and tested. Plus £2 P&P (Monitor not included).

elf 11's VIDEO OUTPUT makes it unique among computers selling at
such a modest price. The expanded ELF 11 is perfect for engineers,

business, industry, scientific and educational purposes.

ELF 11 EXPANSION KITS

Power Supply (6.3v AC) for ELF 11
ELF 11 Deluxe Steet Cabinet (IBM Blue)
Giant Board Kit System/Monitor, Interface to/
cassette, RS232, TTY, etc
4K Static RAM board kits (requires expansion power
sukpply)
Expansion power supply (required when adding 4K
Rams)
ASC11 Keyboard Kilts 96 printable characters, etc.

¢ ASC11 D/lux steel cab {IBM Blue)
Kluge prototype board (build your own circuits)
86 pin Gold plated connectors each
ELF Light pen writes/draws on TV screens
Video graphics board 32/64 characters by 16 lines
on TV/monitor screens
ELF 11 Tiny basic on cassette
ELF 11 Bug/ monitor powerful systems monitor/ editor
T. Pitman short course on tiny basic manual (nil VAT)
RCA 1802 users manual (nil VAT)

® On cassette Text Editor; Assembler, Disassembler
(each)
Save 10% and buy all three together.

PRACTICAL COMPUTING January 1980

£5.00
£23.00

£36.00.
£69.44

£19.00
£60.58
£16.02
£12.83
£4.00
£6.50

£69.95
£13.50
£13.50
£4.00
£4.00

£16.95

ELF 11

SPECIFICATION

“RCA 1802 Bort microprocessor
with 248 byte RAM

expandable to 64K bytes

“RCA 1861 video IC to display
program on TV screen we the RF
Modulator

Single Board with

Professional hex keyboard, fully
decoded to ehmiante the waste
of memory for keyboard decoding
Greurts_

Load, run and memory protect
switches

16 Registers

Interrupt DMA and ALU

Stable crystal dock

Buitt in power regulator

§ slot plug in expansion bus

(less connectors} supplled

wired and tested

RACAL AP12, C12 TAPES: 10 for £4.50 + VAT
NOW AVAILABLE 8K FULL BASIC FOR ELF 11
NEWSOFT GAMES FOR ELF 11: 4 for £5 + VAT

SEND SAE FOR COMPREHENSIVE BROCHURE

Please add VAT to all prices (except manuals), P&P £2.
Please make cheques and postal orders payable to NETRONICS
or phone your order quoting BARCLAYCARD, ACCESS nuniber

To Newtronics 138 Kingsland Road
All units can be London E2 8BY
Tel: 01-739 1582

SOLE U.K.
AGENTS

DEPT. P/C

135

CPS

DATA SYSTEMS

The
Midlands

Micro
Sales Centre

Established by CPS to ensure that you buy the
micro best suited to your particular need.
During your visit you can see, and try at
leisure a whole range of microcomputers.

Expert advice is always on hand to guide you

through our hardware, software and
back-up services.

We're Authorised Dealers for Pet, Apple, Rair
and Transdata microcomputers;

Decision Data and Datac printers;

and Lear Siegler terminals

—all available off-the-shelf;

CPS (Data Systems) are
exclusive Midlands Distributors for
the outstanding

Panasonic

Business Computers.
Phone us today, to arrange your visit, or for
product information.

Telephone: 021-707 3866

CPS (Data Systems) Ltd
Third Floor, Arden House, 1102 Warwick Road,
Ly Acocks Green, Birmingham B27 6BH

A member of the CPS Group

® Circle No. 255

136

The

is here

LOGITEK announces the arrival in the U.K. of the
latest ALTOS Sun Series 8000 computer — rated by
many as one of the most sophisticated micros on the
market.

Consider these features:
HARDWARE

*“CPU:Z80 single board microprocessor, 4 MHz

* RAM: 48-64 kilobytes

*ROM: 1 kilobyte

"DISC: 1 Megabyte

“Drives: Shugart, two 8 inch single sided, double

density

*1/0:2 RS 232, 1 Parallel

*DMA: Z80 (optional)

*FPP: AMD 9511 floating point

processor (optional)

SOFTWARE

* CP/M Disc Operating System

* CBasic (extended basic)

* Fortran 1V (Compiler)

* Pascal

* Cobal

* Macro assembler (Z80)

* Microsoft Basic

Logitek in conjunction with its own microsoftware
house, Interface Software Ltd. of Canberley, is
able to supply a wide range of proven ‘off the shelf’
business software, including word processing.

If you are a dealer who may be interested in
promoting the ALTOS and wish to know more —
contact Logitek — we have something rather special
to offer you.

LOG:

E.1.C. Electronics Ltd., and at

30 Kelvin Avenue, Portland Street,
Hillington Industrial Estate, Chorley,

Glasgow. G52 4LH Lancs.

Tel: 041-882 1166/1661/1662 Tel: Chorley 66803.
Telex. 777255

e Circle No. 256
PRACTICAL COMPUTING January 1980

L &.

Com PUTERS

3 CRUNDALE AVENUE, KINGSBURY NW9 9PJ_ 01-204 7525
THE “PET” SPECIALISTS

HARDWARE

COMPARE OUR PRICES!

PET 8K

PET 16K

PET 32K

EXTENSION CASSETTE DECKS (WITH COUNTER)

DUAL DRIVE DISK UNITS
PET 3040

COMPUTHINK 400K
COMPUTHINK 800K

PRINTERS

PET 3022

CENTRONIC 779 (Tractor feed)
SWT PR 40 (Inc Interface)
(becomes an on-line printer)
TELETYPE 43

SUNDRIES

TOOL KITS

VARIOUS INTERFACES

FLOPPY DISCS

PAPER: ROLL & TRACTOR FEED

FULL RANGE OF PETSOFT & COMMODORE SOFTWARE
/f you can’t see what you want — ask.

We pride ourselves on getting what the Customer wants — quickly!

PRICES DO NOT INCLUDE VAT

£740
£830
£998

£640
£869
£295

£875
from £55

from £40
from £2

SYSTEMS

WE OFFER SMALL BUSINESS SYSTEMS FOR UNDER £2600
WHICH CAN NOT ONLY CARRY OUT MOST OF THE DAY TO DAY
CHORES, BUT ALSO HAVE ROOM TO SPARE TO COPE WITH
THOSE ‘‘ODD JOBS”. TAKE YOUR CHOICE!

EACH PACKAGE COMPRISES A ‘PET’ 32K, CABLES, ANY
INTERFACES REQUIRED, BUT DOES NOT INCLUDE PAPER,

mt.
_

SOFTWARE

As well as a full range of Petsoft and Commodore Software, we
hve some highly reliable ‘“‘Home-Brewed"’ programs available.

STOCK CONTROL & INVOICING £60
(Handles up to 500 items — 32K) (180 on 16K). Stock depleted on
invoicing, search etc. Cassette, disk {& print option).

STOCK CONTROL & INVOICE (RANDOM ACCESS) £120
On-line handling of 3400 items (50 char.) per disk. Disk (+ printer
option) (16 or 32K) search etc.

ADDRESS/PHONE BOOK

Create, amend, enlarge, search {+ print option) (16K or 32K).

MINI CAB/DELIVERY INVOICE & DRIVERS WAGES £220
Weekly or monthly invoices — cheque writing facility — optional
deductions. (16 or 32K + disk + printer).

INFORMATION RETRIEVAL £130
Multi field; multi item; infinitely variable. Print facility: automatic
sort.

ALARM CLOCK £5
See the time — hear when you're overdue! (All Pets).

YOUR MONTHLY PLANNER £7
Print your own planner on your own printer! Any year or month.

RANDOM ENTRY & ANALYSIS £40
Makes adding up all those different invoices childs’ play! Cash,
cheques etc., balances & VAT.

SCHEDULE 'D’

Check your own tax without being an accountant!
SEND SAE. FOR FREE BROCHURE

PRICES DO NOT INCLUDE VAT.
We can write specialist programs for you. Ask us for a quotation.

BASIC COURSE

IN RESPONSE TO MANY REQUESTS AFTER OUR VERY
SUCCESSFUL ONE-DAY PROGRAMMING COURSE, WE ARE
RUNNING ANOTHER ON THE 5th FEBRUARY 1980 AT THE SAME

£35

£25

VENUE (EUROCREST HOTEL, WEMBLEY). COST fincluding Hotel
Lunch, etc & VAT) £46.

EARLY APPLICATION !S ADVISED !F YOU WANT A PLACE.
S.A.E. FOR PROGRAMME & APP. FORM.

ACQUISITION

You are welcome to try, browse & purchase at our premises.

You can phone your order.

You can fill in & send off the form below.

Whichever way you choose, you cannot help but be delighted with
our service. .

ORDER FORM

TOL & J COMPUTERS:
PLEASE SEND ME BY RETURN: —

| TRACTOR FEED PRINTER
PET 2022 TELETYPE43

DUAL DRIVE
DISK UNIT

COMPUTHINK
200K x 2

PRICES DO NOT INCLUDE VAT

DISKS ETC.
CENTRONIC779

ADD £9 for large items
ADD 50p for small items
VAT €£

TOTAL €
CHEQUE/P.O ENCLOSED*
CHARGE TO MY ACCESS/BARCLAY/VISA CARD No.*
(*delete as req'd)

ALL GOODS SENT SAME DAY WHEREVER POSSIBLE — [re |
Recorded delivery by post: or Securicor. ** aan /

PRACTICAL COMPUTING January 1980

You've heard about it
Read about it — HERE ve is

AVAILABLE EX-STOCK Nw
COMPLETE KIT AS PER *y lo
MANUFACTURER'S SPECIFICATION Gy 5,°2

With provision for 8K on board expansion. Excludes 4118 x8« Ds Cn,

AERCO GEMSOFT

APPLE 2 Comes to Woking!

Aerco Gemsoft have just opened their new computer division in Woking and invite
you to drop in for a look at some real computers: —

APPLE 2
SUPERBRAIN
MICROSTAR 45
OHIO SCIENTIFIC

We are official Apple agents and southern area distributors for the Intertec Superbrain.

4 “Cy
INCLUDES FREE 16K EXPANSION ty

VALUE £140 includes ALL parts with every kit
&

i =
NASCOM-2 £295 ii” nee
ON DEMONSTRATION NOW | 16k EXPANSION WORTH £140

AVAILABLE ONLY FROM US ON THE COUPON BELOW
OPTIONAL EXTRAS BOFF4118*

r Apple 2 16K (Europlus B & W) £750.00

ieee “id POWER patios la a Superbrain 64K (Twin Disks) £1998, 00

Vf - asers ITT 2020 16K (Colour) £867.00

£29.50 al is Early Microstar 45 Plus £4950.00

i : £80 pelivery Appte 2 Disk Units from £355.00

For NASCOM-2 16K Memory Upgrade Kit £69.00

Serial/Parallel Interface Card £110.00

RS232 COMPATIBLE Pascal Language Card £296.00

80 COLUMN PRINTER OUR PRICE ere one ae
brand new + VAT Hitachi Monitor :

6 z 2 "* Hitachi Monit £210.00

List price £550. If sent by carrier £5 extra £325 15% cir none a £40.00

E i Card
FULL MANUFACTURER'S WARRANTY — DON'T DELAY. ORDER TODAY pccaritae

Please send me my NASCOM.-2 KIT with the FREE 16K EXPANSION
for £295 + VAT.

! enclose remittance to cover

DISK BASED BUSINESS SOFTWARE FOR APPLE 2/ITT 2020

SalesLedyer Payroll
Stock Control General Ledger
Invoice Printer Price List Maintenance

Name & Address Please add 15% VAT to above prices.

Send S.A.E£. for full catalogue containing over 100 programs for PET, Apple & Exidy
Sorcerer. Trade enquiries welcome.

Also in stock NASCOM.-1 @ ELF @ TRS80 as previously advertised

HENRYS =)

Computer Kit < fe
404 Edgware Road, London, W 2, England
01-402 6822

Gemsoft can supply you with a complete (and fully expandable!) Apple system off
the shelf including twin disks & printer for £2431 + VAT.

We specialise In designing complete systems and our expert in-house programmers
are available to write any customised software from business systems, through
industrial control systems to scientific and research programs.

GEMSOFT LTD, 27 Chobham Road, Woking, Surrey. ere Woking (04962) 22881.
Open 6 daysa week 9.30-5.30 p.

13 WARWICK ROAD

SIRTON PRODUCTS (sp) coutspon

SURREY Tel: 01-660 5617

MIDAS S100 SYSTEMS

Substantial Mainframe to house your $100 system, with optional

-— 5in. or 8in. disc drives. Special systems built to your requirements
from Z-80 CPU and other $100 boards held in stock.
Mainframes from £228
ne y MIDAS 1 : Z-80 System from £625 (built)
7

MIDAS 2: Z-80 5in. Disc System from £1,100 (built).
MIDAS 3: Z-80 8in. Disc System from £1,300 (built).

ITHACA INTERSYSTEMS DPS 1

Professional versatile computer system with comprehensive front-
panel facilities and 20-slot motherboard. Units have substantial
power supply etc. and come with 2 or 4 MHz Z-80 CPU. BUS
conforms to the IEEE $100 standard.

DPS.1 from £695

COMPREHENSIVE RANGE OF S100 BOARDS AND SOFTWARE STOCKED
from
ITHACA INTERSYSTEMS ° SD SYSTEMS - GODBOUT - CROMEMCO -

E Gale Sioivi Etc =
eee Write or Phone for Catalogue e)
¢ Circle No. 260
138 PRACTICAL COMPUTING January 1980

IN A CLASS OF TTP’S OWN
SUPERPAY FROM COMPUTASTORE

Professional standards and software support of
the highest order are guaranteed features on all
Computastore programs.

Other packages for the PET Series
Microcomputers include:

: PETE —turns PET into an intelligent RS232 terminal

ASSEMBLER > iad up to 500 lines
— with erful
DISASSEMBLER seat 3c"
ie i da
KEYBOARDS”

PRACTICAL COMPUTING January 1980

Unrivalled for speed and accuracy our new
Superpay Payroll Program guarantees the
PET user all the advantages of precise

full payroll computing.

i Unique Screen Layouts

2. Easily understood duplicate payslips

KB Payroll master file reporting and
departmental analysis

4. Credit Transfer payments and coin analysis
5. Automatic Year-End analysis
6. Security and confidentiality

7. Reliable updating service for rate changes

The main features of Superpay are also incorporated
into the Standard Disk and Cassette Options.

Computastore

Software that means business

Ask your local PET dealer or Computastore for a demonstration

COMPUTASTORE Ltd., 16 John Dalton Street,

Manchester M2 6HG. Tel: 061-832 4761
° Circle No, 261

139

Possibly the most
cost effective word
rocessors in the wort

The Vector Graphic MZ

i CPU The Vector Graphic System B
630K Bytes disk storage Plus a large range of CP/M compatible software Complete Vector MZ system plus: *
:&Serial port and two parallel ports including Fortran, Cobol, Macro assemblers etc. * Vector Mindless terminal *
%*Prorm/ram Board with monitor a Flashwniter 2 video board (24 x 80) *
3MDOS Operating system : +#Software driver on prom:
£280 Assembler MZOS North Star compatible DOS *
Basic Interpreter %* CP/M configured by Almarc

uain tox SORCERER stockists TRS 80
EMG ol 688 0088 a

COMPLETE 32K SYSTEM
WITH VDU CASSETTE

WORD PROCESSING PLAYER EXPANSION

INTERFACE TWO R0K

SYSTEM b1999 CASE MOD £1600
ESTATE AGENT MICROPOLIS

DISC DRIVES £325

SYS T E M § 245 g LOWER CASE MOD £28
COMPLETE BUSINESS essere ar
SYSTEM £0909

INC.630K DISC STORAGE & PRINTER

MAINS STABILIZATION
KIT £30

232 INTERFACE TO
SYSTEMS DESK £170 MEMORY UPGRADES MAINS — STABILIZATION TELETYPE 43 £45

COOLING FAN POUND MOD TELETYPE 43. FULL SERVICING NNDERTAKEN
Nee GAMES CASSETTE £5

6 C0 PIES 0 F SOURCE THE SORCERER MAGAZINE £5 GAMES DISKETTE £7

GAMES CASSETTE £6 GAMES DISKETTE £8 FULL SOFTWARE

EMG 121
ON REQUEST roEMG MIGROCOMPUTERS LT VARIOUS SOFTWARE

WRITE TO EMG 121
30 HEATHFIELD ROAD CROYDON SURREY ALL PRICES EXCLUDE VAT

BROCHURE ELECTRIC PENCIL £100

® Circle No. 263
140 PRACTICAL COMPUTING January 1980

Adams, C., Beginners’ Guide to Computers and Microprocessors With

Projects £ 5.70
Ahl, Basic Computer Games £15225
Albrecht, B., Basic for Home Computers £4.95
Alcock, D., Illustrating Basic £ 2.60
Altman, L., Microprocessors £10.65
Aitman, L., Applying Microprocessors £12.00
Aspinall, D., Introduction to Microprocessors £ 6.50

Barden, W., Z-80 Microcomputer Handbook £7.05
Barden, W., How to Buy and Use Minicomputers and Microcomputers
£ 7.85
£7225
£ 8.60
£12.60
£11.70
£ 6.00
£ 6.00
£11.80

Barden, W., How to Program Microcomputers

Barna, A., Introduction to Microcomputers and Microprocessors
Bibbero, R., Microprocessors in Instruments and Control

Boyce, J.C., Microprocessor and Microcomputer Basis

Bursky, D., Microcomputer Board Data Manual

Bursky, D., Microprocessor Data

Bux, W., RPG and RPGII Programming

Clifton, H., Business Data Systems

Coan, J., Basic Basic

Coan, J., Advanced Basic

Conway, R., Intro. to Microprocessor Programming using PL/Z £14.00

Conway, R., Intro. to Programming, Structured Approach using
PL1-PLC 14.00

£ 6.00
£ 7.80
£ 5.80

£ 4.00

Ditlea., A Simple Guide to Home Computers
£13.60

Duncan., Microprocessor Software Engineering

Eadie, D., Microcomputers Theory and Operation £13.10

Micro-
£ 5.60
£ 7.20
£ 3.95
£ 4.95

Freiberger, S. Consumers’ Guide to Personal Computing and
computers

Frenzel, L., Getting Aquainted with Microprocessors

Fry, T., Computer Appreciation

Fry, T., Further Computer Appreciation

Gilmore, C., Beginners’ Guide to Microprocessors £ 4.85
Gosling, R., Beginning Basic £ 4.75
Graham, N., Microprocessor Programming for Computer Hobbyists

7.10

Grosswirth., Beginriers’ Guide to Home Computers £ 4.50
Hansen, P., Operating System Principles £16.30
Hartley, Introduction to Basic £ 2.60
Haviland, N., The Compulator Book £ 6.50
Heisermand, D., Miniprocessors from Calculators to Computers £ 5.00
Higgins D., Programmed Design and Construction £ 7.50
Hilburn, J., Microcomputers Microprocessors Hardware/Software
Application £17.00
Hill, F., Digital Systems Hardware Organisation and Design £ 9.00
Huffman, J., Microprocessors in Personal Computing £11.10
Hunt, R., Computers and Commonsense £ 4.00
Johnson, D., Digital Circuits and Microcomputers £13.10
Jung, W., IC OP AMP Cookbook £10.00
Jung, W., IC Converter Cookbook £ 9.50
Jung, W., IC Timer Cookbook £ 7.50
Klingman, E., Microprocessor Systems Design £17.00
Kemeny, J., Basic Programming £ 6.50

Korn, G., Microprocessor and Small Digital Computer Systems for
Engineers and Scientists £19.00
Kraus, L., Computer Fraud and Counter Measures £21.50

Lancaster, D., TV Typewriter Cookbook Ea TAL
Lancaster, D., Cheap Video Cookbook £ 6.50
Lancaster, D., TTL Cookbook £ 7.00
Lancaster, D., CMOS Cookbook £ 8.20

Lancaster, D., Incredible Secret Money Machine (How to set up your
computer or technical business) £ 4.95
Lenk, J., Handbook of Microprocessors Microcomputers and Mini-
computers £14.00
Lenk, J., Handbook of Practical Microcomputer Troubleshooting £13.00
Lesea, A., Microprocessor Interfacing Techniques £ 8.00
Leventhal, Introduction to Microprocessors £16.70
Lewis, T.G., Mind Appliance Home Computer Applications
Libes, S., Small Computer Systems Handbook
Lippiatt, Architecture of Small Computer Systems

Mano, M., Digital Logic and Computer Design
Munro., Interactive Computing with Basic
Munro., Basic Basic

Moody, R., First Book of Microcomputers

PRACTICAL COMPUTING January 1980

COMPUTING BOOKS

McGlynn, D., Microprocessors Technology Architecture & Applications
£ 8.60

McMurran, Programming Microprocessors
Myers, S., RPG II with Business Applications

Nagin, P., Basic with Style

Nahigian., Computer Games for Business Schools and Home £10.50
Ogdin., Software Design for Microcomputers £ 7.00
Ogdin., Microcomputer Design £ 7.00
Peatman, J., Microcomputer Based Design £ 7.00 |
Peatman, J., Design of Digital Systems £ 7.90
Peckham, Hands on Basic with a Pet £ 8.70
Peckham, Basic A Hands On Method £ 6.95
Rosen, A., Word Processing £11.60
Rao, G., Microprocessor and Microprocessor Systems £20.50

Rony, P., 8080A Bugbook Micromputer Interfacing and Programming

£ 8.20
Scelbi., 6800 Software Gourmet Guide and Cookbook £ 7.80
Scelbi., 8080 Software Gourmet Guide and Cookbook £ 7.80
Scelbi., Understanding Microcomputers £ 8.80
Schoman, K., The Basic Workbook £ 4.00
Sipple, L., Computer Power for Small Business £ 7.50
Sirion, D., Basic from the Ground Up £ 6.25
Snover, How to Program Your Programmable Calculator £ 6.00
Sourcek, B., Microprocessors and Microcomputers £19.00
Spencer, Game Playing with Basic £ 5.00
Spencer., Computers in Society £ 4.00
Spracklen., Sargon (Computer chess program in Z-80) £10.00
Streitmatter, G., Microprocessors Theory and Application £12.50
Titus, C., 8080/8085 Software Design £ 7.60

Titus, C., Microcomputer Analog Converter Software and Hardware

Interfacing £ 7.60
Tocci, R., Microcomputers and Microprocessors Hardware/Software
£11.80
£ 4.50
£ 6.60

Tracton, K., Basic Cookbook
Tracton, K., 57 Practical Programs and Games in Basic

£13.00

£ 6.50
£ 1.50

Veronis., Microprocessor Design and Applications

Waite, M., Microcomputer Primer

Waite, M., Your Own Computer

Welsh, J., Introduction to Pascal

Wirth, N., Algorithms Plus Data Structure = Programs
Ward, Microprocessor/Microprogramming Handbook

Yourdin., Structured Design

Zaks, R., Introduction to Personal and Business Computing
Zaks, R., Microprocessors from Chips to Systems
Zaks, R., Programming the 6502

Zaks, R., 6502 Applications Books £ 8.60
Zelkowitz, M., Principles of Software Engineering £15.00
TVT 80A—Z £ 4.25
TVT 802N £ 4.50
THT 77 £ 4.50
TIL 79/80 £ 6.50
DATI A-BUG Data Dictionary £ 6.95
LINI £ 4.00
LIN II £ 4.20
Digital IC Equivalent Book £ 5.50
DIO DE Data Book £ 2.60

What Is A Microprocessor 7

SEND TO:

TECHNICAL BOOK SERVICES
PC12 PO BOX 79,
MAIDENHEAD,

BERKSHIRE SL6 2EG

A division of Strathearn Publishing Ltd.

Please note that all prices include postage and packing. Please
make cheques, etc. payable to Technical Book Services. (Payment
in U.K. currency only please).

THE ELECTRONIC REVOLUTION

SPECIAL OFFER — 8K PET £995 ex. VAT (+ p&p £15 in U.K.)
%*& SPECIAL VALUE! GAMES GALORE!

For your PET 20 different games on disk or tape for £23 inc. VAT (+ SOp p&p) — media included.

It sounds like a steal! All originals, most games with super graphics.

1. Cannibal Island 8. Junior Hangman 15. Howitzer

2. U-Boats 93. Death Race 2000 16. Doodlebug

3. Minefield 10. Ski Slopes 17. Brands Hatch
4. Oth+tllo 11. Master Mind 18. Battlestar

5. Draughts 12. Fly Swat 193. Dambuster

6. Star Wars 13. Evens 20. Rugby

7. Hangman 14. Rocket Attack

Also: Serial ASCIi unidirectional interface for PET to RS@&S3ec
(Turn your PET into a wordprocessor) £92 inc, VAT (+£1 p&p)
Well Ring my Chimes! DOOR CHIMES. 24 fantastic electronic tunes to amaze your friends when they
‘ring your bell’ — Complete £12.50 inc. VAT (+ £1 p&p)
PET DEMO CREATOR
Create your own personalised automatic demonstration — large characters all built-in — just say what
you want to say! A new demo everyday £10.
MAIL ORDER
Written orders with cheque or Access/Visa No. to:

6 Criterion Arcade, Old Christchurch Road, Bournemouth.
Please supply:
BITE. 0. sscsscseeesss syetore - ee ee ee ee COUNT eiesencncnicn Ratner

ENA ING Se sib 8a: nos nnencteeerieetpaeacenmmannenn ieneaseeivnemuerresenMie ote oot seFhgaaaee CMEGIWIEING..ssce cecctenesinncctegen cscs crrcierteseccsss ceric mereenerenees

Name ; Address ——_— ACCESS/VISA NO.

COMPUTER BOOKS *
Introduction To Microcomputers Vol 0 5.45 bi BOBO Gourmet
Introduction To Microcomputers Vol 1 6.30 seer! en Geurrne Sara
Introduction to Personal and Business Computing £5.45 Sceib! 8080 Standard Assembler
6800 Assembley Language Program 6800 Program For Logic Designer

Scelbl 6800 Gourmet Guide VERO PRODUCTS

0.1" Copperciad Boards

TTL Cookbook

CMOS Cookbook

Cheap Video Cookbook
TY Typewriter Cookbook
80804 Cookbook

Using 6800 Micros.
Progtammung 6502

15 Z-80 Microhandbook

48p 60p
56p , T10p
" 56D 275p
8080 Machine Language Program 8080 Program For Logie Designer

BOBOA/808S Assembley Language Program 30 2.80 Program For tou Detioer
Computerisation For Small Business 98 8080/8085 Software Design

No VAT on books, Pisase add 55p p & p per book,

DIP BREADBOARDS:

V-0 Dip Breadboard (No track cutting) 105p
Dip Breadboard with Busbars (4,15 6. 151 2609
Dip Beeadboard sultable for 19° Card Frame System with

OTHERS f 31 Way Tracks 2350p
45 SUS SERIES 31 Way Plug for the above 110p

pat soa 2 31 Way Socket to fit the above 0p

74L$10 VERO S100 SUB RACK £202
74LS13 PEP ta
74LS20 2732 (19" rack mountable development kit, complete with power supply and back:
74LS30 . plane motherboard, for construction and evaluation of microprocessor sytem
74LS32 if to the S100 format)

6809
SC/MPII 40 Be eee VERO S100 SYSTEM CARDS AND ACCESSORIES
80804 ? ae Code Description
zB0 7490 CHARACTER GENe 06-0095L $100 Dip Board
ZBOA 74L$107 3257ADC 06-2337L_ S100 High Density Board
MEMORIES 748123 MCM6576 06-7338F S100 Square Pad Board
2102-21. crc 650p 74S 124 RO-3-2513UC 09-2340H = $100 Extenderboard
21078 Jatsyas RO-3-2513LC 76-2867G Keyboard Console
2111-2 bas SN74S262AN ‘ 200-21341D Vero Wiring Kit comprising Vero pen, spere spool + 25 combs
2112.2 KEYBOARDENCODER -
Bie 74S 132 Poets
21141300 pneise ADIDA CONVERTER
4146 74L$165 209
a 74.515? ‘ VOU INTERFACE KITS sacl
Ci t Tint yng simple to construct VDU interface kits
s10 pres INTERFACE ICs Meer eieeiied VOU enatans it oe oe
ROMIPROMe 74LS165 8123 (wath on board modulator)
25810 74L§221 75107 (dea! tor KIM, MK 14, MEKD2, end eny other microcomputer system which
745188 Ol SOCKETS 74.8244 has seven sagment readouts only.
748287 74.S273 Elekterminal Serial 1/0 VOU interface Kit £62
148387 ae : 74L$365 UHF Modulator £4.20 extra.
745470 re 74LS367 When used in conjunction with ASCII Keyboard, the aystem can be used as 8
748471 bin 74LS368 stand alone videowriter or a complete video data terminal with any microprocessor
oud 1250 741$373 syetern using serial I/o facility,
i 74.$374
93446 aon 7408378 INSB295 4K NIBL ROM
a 748393
Pate ARAB LER mee COUNTERS EDGEBOARD CONNECTORS 0.156” PITCH
SFF96364 pin Full 74, 74LS & CMOS 2™ 10 Way 85D
= = ine a eke
rv ip

Manan
avoNvewn
REKFRRES

50
x»
30
2

™

VOLTAGE REGULATORS OPTO-ELECTRONICS DL704 1400 TH312/3. 110;
Fixed Plastic TO 220 2N5777 45p DAPEO DL707 Red140p Tit321/2 sae
+ve —ve QOCP71 1130p ORP61 707GR 1340p TIL330 © 140p
7908 oe ORP12 —_—90p TIL78 DL747 Red22Sp 7750/60 200p
OPTOASOLATORS 747Gr 2Z26p DRIVERS BREADBOAI PR Al
cde foe sae (L074 ane ues) 908 £0367 120p %I%E %°°P SEO ees Boanaee AD (A) SOLDERLESS BREAO.
iP iP ND: 120p % 4)" eeP (Up to 3 x 14 pin ICs) “Socket Strips /Bus Strips/ Binding P
toma TOS ta 190p TILII6 90p FNC507_ 120p UDN6t18 320p EXPESO3 6° roe" on sturdy base aie ee ae
ee I is 5 a2 MAN3640 175p UDN6164 320p (Up to 1% 40 pin IC) PB6 6m 14 DIL ICs £9.20
Vicente 11220 Red 16p MAN4640 250p EXP300 6” x) 1" PB100 10x 14 DIL ICs £11.20
i ere ee 6p TK222Gr 18p ANTEX SOLDERING IRONS (Uto 6x 14 pin ICs) PB102 12% 14 DIL ICs £22 96
OTHER REGULATORS TIL209 Red 13p TIL22B Red 22p C-15 15W 400; EXP600 6" x 2.4” 30 PB103 24 14 DILICs £34 4B
LM309K135p TBA625B Tee Se ee CCN SW (Up to 1x 40 pin DCaD P8108 32 x 14 DIL ICe £45 96
LM3t7T 200p 7BHGKC TER ie ae a isd Lee (The above boards are suitable for all DIL ICs.)
it
LM323K —§50p 7BHOSKC OISPLAYS NSB5881 670p UHF MODULATORS

LM72337p TEMGT2C 301SF 200 THLSI1 Gone pt =~
BMH:

VAT: Please add 15% to total Please add 30p p&p. TECH N O M ATI C LTD 8

Access and Barclaycard accepted Government, Colleges, etc. Orders accepted. 17 BURNLEY ROAD, LONDON NW10

ees .-Fri. 9.30-5.30 inut llis Hill ti nple street parking).
(hficimum Card nOHOOLOMer EO CAMMEMRUMEUOME Seetegea fpr een omens estan en

e Circle No. 266
142 PRACTICAL COMPUTING January 1980

A NEW Micro-Computer Centre
a for the MIDLANDS

NOW OPEN IN KENILWORTH

Business & Leisure Micro Computers Is now
open in Kenilworth. Stockists of well known computer
systems and micro processors. B&L Micros offer a
user service which will be of special interest to the

Dp
yy LN

NASCOM 2 is HERE

Nascom 2 complete kit
ex stock £295.00 + V.A.T.

plus ¥ businessman as well as the hobbyist seeking a new and
DUCTOR exciting challenge.
SUPER INTRO
OFFER

A full range of micro computers and peripherals
are available. Books, instructional material and
software. Call in and talk over your requirements.

REE 16K Memory
t aeiee board worth
€140.00

_____s\ Free software given away with every PET
or Nascom bought. All models in stock.

Also available

NASCOM 2 fully bullt and

tested £335.00 + V.A.T.

POWER SUPPLY KIT for
Nascom 1 or 2

ef We stock ALL you need to build your Nascom - tools, soldering irons, add ons etc.
& Try before you buy — we sell time on a full range of machines at economic prices.

¥ Printers, floppy disks, cassettes, paper, books, components.

£29.50 + V.A.T.
A Special B&L Micros We can offer computer time for business users and
fi m Service Selling others. Our Nascom and PET's can be hired by the Ce comocone
7 hour or day for software devel t. Enquiries are
ORDER NOW Nation Maciocomeulere Computer Time privniol. y for software development Quirie:

Business & Leisure Micro Computers

16 The Square, Kenilworth, Warwickshire CV8 1EB. Tel: (0926) 512127
¢ Circle No. 267

is
Access Barclaycard

TRS-80 OWNERS!

LEVEL Il CASSETTE DISK

ADVENTURE (LAND)*
ADVENTURE (PIRATES)*
AIR RAID*

AMAZIN’ MAZES
BACKGAMMON
BALLOON RACE
BARRICADE*
BASEBALL

BATTER UP

BINGO

BOWLING (TEN PIN)
BREAKAWAY
BRIDGE CHALLENGER
DOGSTAR

END ZONE
FASTGAMMON®
GALACTIC BLOCKADE
HAMURABI
HANGMAN
KAMIKAZE
KENTUCKY DERBY
LUNAR LANDER
MASTERMIND*
MICROCHESS*
MISSION IMPOSSIBLE*
OTHELLO Ill
PENTOMINOES

PORK BARREL
REMAINDER
ROBOTS

ROUND THE HORN
SAFARI

SANTA PARAVIA
SARGON*

SINK'UM

SPACE BATTLES
STARTREK III

TIME BOMB
TREASURE HUNT
TREK 80

TAIPAN

TYCOON

X-WING FIGHTER
WARFARE |

PRACTICAL COMPUTING January 1980

N
&

PPENTDWWONNWS SE TWEDTwWISS SWeWWEVEONWEWWEANOERENN

LncTac Mac l acl acl nc Mec MacleclaclacMacl acl acl ac lalaclec lala lecla ladle la laclaclacleclacl acl Lacleclac la Taclaclaclaclaclaclac!
SSSSSSseessssssssssusssessseuseusssssusssuy

ACCOUNTS RECEIVABLE
APPOINTMENT LOG
ASTRONOMY II
BIORYTHMS

CALENDAR FUNCTIONS
CALCULATOR

CASH REGISTER
COMPLEX MATHS
CURVE FITTER

ELECTRIC PENCIL®
ELECTRONICS ASSISTANT
ESP TESTER

FILE HANDLING
FINANCE (LOANS & INVEST)
FINANCIAL PACKi
FINANCIAL PACK II
FOURIER TRANSFORMS
GENERAL ACCOUNTING
HAM RADIO

HOME FINANCE
INVENTORY MOD.
INVENTORY FP.
INVENTORY CONTROL
KEYBOARD-80

KVP EXTENDER

LEVEL Ill BASIC

LINEAR PROGRAMMING
MATH DRILL
MICROTEXT
MORTGAGE CALCULATOR
NUMERICAL INTEGRATION
PERSONAL FINANCE
PRE-FLIGHT

RPN CALCULATOR
RENUMBER*

ROOT FINDER

SCREEN PLOTTER
SIMPLE SIMON
STATISTICS |, ti, ill

STAR FINDER

SYSTEM COPY*
LIBRARY 100

75 BASIC PROGRAMMES
MANUAL FOR ABOVE

AANAAAAHWASAaMwowaumd
SSSSSSesSsessexsssssyss

PP MMMM MMMM MMMM MMMM MMMM MAM MMMM MMMM MMMM Mmmm MmMmMmm

ACCOUNTS RECEIVABLE II
ADVANCED PERSONAL FIN.
AMATEUR RADIO SYSTEM
GENERAL LEDGER II
INVENTORY 2.2

INVENTORY 2.3
INVENTORY II

LEVEL JIN LEViIRAM

MAIL LIST Il

NEWDOS +

TEXT:
ST 80-D

PPM Mm PP Mmm mmm rm
S8ISSSESESSS
SSsssssssess

TARANTO & ASSOCIATES CONVERSION
OF OSBORNE & ASSOCIATES BUSINESS

PROGRAMMES.
ACCOUNTS PAYABLE
ACCOUNTS RECEIVABLE
GENERAL LEDGER
PAYROLL

MANUALS FOR ABOVE
76 BASIC PROGRAMMES.
MANUAL FOR ABOVE

*DENOTES MACHINE LANGUAGE
SEND 50P FOR FURTHER DETAILS

OF ABOVE PROGRAMMES.

ADD 50P TO ORDERS UNDER £20.00

DEALER ENQUIRIES INVITED.

Pm Mmm mem
ons88ss
8888sss

ALL LISTED PROGRAMMES IN STOCK.

FOLLOWING AVAILABLE TO ORDER.

FORTRAN

cP/M

MMSFORTH CASSETTE
DISK

PILOT

MICROCOMPUTER
APPLICATIONS

11 Riverside Court, Caversham,
Reading, RG4 8AL, England.

® Circle No. 268
143

HOME +
BUSINESS
COMPUTERS

‘“*PET SHOP”’ FOR THE HOME AND
SMALL BUSINESS MAN 8K—16K—32K
“THE QUICKNESS OF THE CHIP DECEIVES THE

EYE’’ WITH SORCERER 32K OF MAGIC. THE
IDEAL SYSTEM FOR THE MORE AMBITIOUS
HOME USER AND THE BUSINESS MAN FLOPPY
DISKS PRINTERS-WORD PROCESSING

BOOKS, MAGS, TAPES GALORE!

Add a little colour to your life with APPLE/ITT

2020 what better use for your colour TV?

Stock arriving by the day. Please phone for further
information.
WE ARE HERE

East Ham Sin

Hig St. North Woolwich Ferry —om

Manor Park Stn, Strattord

455, High Street North,

Manor park,

LONDON E.12

Tel: 01-472 5017 (24hr Ansaphone)

¢ Circle No. 269

“SORCERER'S APPRENTICE

Wide range of software available for the Sorcerer:
DRAW draws pictures on the screen and saves on
CaSSAtte accent ape 28 Le hia oats SERA Ss 4.60
LINK links basic programs together: renumbers
PrOGKANNS)..: 2... .bew Se. Ce ioniae. : a): false se:
STATISTICS a comprehensive package......
PLOT 2 high resolution plots of polar functions. . 6.90
ALPHA sets graphics to give Greek alphabet and
SCIENCING SYMBDOIS.,..d6 «poss vs geese os eee 5.75
CASSETTES C10’s 50 pence each

All the above prices include VAT
Business programs and software from LIFEBOAT
ASSOCIATES
MICROSTOCK Disc-based stock control with
advanced features e.g. allows instantaneous access to
item details. Package cost 120.00 plus VAT (manual
5.00).
Send SAE for full software list.

WE PUBLISH PROGRAMMES

Good royalties available for quality original
software. Plese send copy for inspection.
EXIDY PRODUCTS full range supplied.
PRINTERS Rioch (daisy wheel) Centronics Dolphin
Printerm

MICROPUTE
7 Westbourne Grove Manchester 20
Tel 0625 612818

Romiord Ad

144

VISICALC

for your Apple

£100 + VAT

Visicalc has to be one of the neatest Software
innovations of 1979. It gives tremendous
flexibility in handling any type of data that can
be organized in rows and columns. This
Software should be useful to Engineers and
Accountants alike; it will be particularly
attractive to business Executives for financial
modelling.

ALREADY VERY SUCCESSFUL IN THE STATES

For your folder, manual, diskette etc. please
send your order together with your cheque to:

PADMEDE COMPUTER SERVICES,
The Tuns, High Street, Odiham, Hants.
Tel. Odiham (025-671) 2434

¢ Circle No. 270

CHS electronics

your soundest connection in the world of components
Dept PC, 56 FORTIS GREEN ROAD, MUSWELL HILL, LONDON, N10 3HN

TELEPHONE: 01-883 3705/2289

AY-5-1013 £4.20
MM 5503

DYNAMIC RAMS
DYNAMIC RAMS 1+
4027
4116 (250 ns)

B1LS 95 99) 74L $00 7p .
STATIC RAMS 3 a1 Niza
STATIC RAMS ets
21028 oe pea
08 .229
14 75p
28 .22p
Z 3 30 21p
MM 5257 (TMS 4044) os Be
MM 2114 £7 18 1p
MC 6810 i 310
4035 (1000 ns) re ae
i }
4045 (250 ns) 151 “935
ROMS 138 apo
2513 {Upper Case) 163 "Sop
2513 (Lower Case) 166 €1.90
MM 5230 179 £1.98
192 £1.20
EVALUATION KIT 193 £1.20
194 .99p
195 £1.12
197 €1.12
21 £1.06
253 £1.06
279 ‘65p
283 £1.25
293 £1.05
348 €1.60
365 ‘5p
74 $00 €0.650 366 4p
74 $387 £2.68 ‘Bap
T.V. CONTROLLER ae | oe se on
SFF 96364 £16.77 74 $262 £12.00 668 £1.35

¢ Circle No. 272
PRACTICAL COMPUTING January 1980

1 the
same day (min tel order

3 Fullafter-sales service in our own workshops
ye One year guarantee onall machines

for under £400

keyboard, computer,
power supply, UHF modulator ©
and all cables to plug into your
own TV set and cassette
recorder and go!!
16K of user RAM for decent size
Programmes and data, Sophisticated
fevel I! microsoft basic.
Fully Converted to UK standard
including frame sync. frequency
(no wobbly display).
Tandy don't do this!
Complete with level | and level |t

Programming manuals. What more
could you ask?

This lot must be today

Improve your
8K PET with

memory expansion boards

i ting,
internally moun

full instructions supplied, '
plug and socket connection

(24K $390 |

4
-

only, 3

characters per second.

Leasing
available to
companies //

‘Omni :

Y) NV
| J / ; ww

Tel: Bath (0225) 28819

Your dealer for Bath, Bristol and S.W.

NWN
f

Computerama

Harpers Kensington Showrooms
London Rd. Bath, Avon

Please add £10 Securicor

delivery on computers

plus 152 VAT on all prices

PRACTICAL COMPUTING January 1980

\ Buy here at discount prices

The only 16k complete computer

Converted to
Anadex Print out without UI K

Paper waking baby! 7001 -8 frame stalk:
Ticer | DP8000 |Trendcom ie) eerste [a wotsy aap

1g dot matrix printer Silent thermal and integral cassette) ~ M0 one else does it!
dot matrix printer | 96 character set, santer
Shae og eee dten 40 column
ak ee tullp auiiictable bidirectional A
sizes, 80 or , printing, 96 e
ssl 10 crates y = 001 — 32N (32K RAM and new large aa £590
adjustable widths aad bidir clear, 10 2 Ten (16K RAM and new large keybo
tractor feed. sec tin Supplied characters per 2001 — en cee an
Centronics type prin Ha with inch, 5 x 7 dot External cassette deck, suitable pe
parallel and RS232 RS232/current loop matrix format at CBM dual drive mini floppy ae
serial interfaces serial and Centronics type | 40 characters fou ierinr feed printer with Pet graphic
ee a parallel interfaces. per second, robust.

. ri |
Unbeatable value! | Knockdownprice! | A snip! Ma k e PET t I
£575 £499 £249 outside id K to the
Interfaces - ; 1EE/RS Fae d
Interfaces- tee Aa, Qhios £10 | Pet £49 Ohios £10 IEE/Agose Serial input/output E1ag
Pet £49 Ohios £10 | Pet 80 £12 Sorcerer £6 | TRS-80 £12 Sorcerer £6 Pet to S100 4 siet Output £89
TRS—80 £12 Sorcerer £6 avail te Apple £49 : motherboard 442
Apple £110

IEE/Centronics
parallel i/f

SS
oo.

Credit card orders accepted

for immediate despatch.

£399

Extra numerical
keypad £33.95
Expansion interface
Complete with

32K RAM £299

‘s best buy!

£45

BARCIAYCARD ¢
VISA

VISA

telephone

e B mane nurs

IN L\SCOM S = :

the Nasco ahot soldering iron

: mi
Britain’s big S NOw supplied BUILT!
Here’s anoffer youcan'trefuse:

Because of the lack of availability of MK 4118
RAMs, Nascom Microcomputers is supplying its
Nascom 2 without the 8 spare 4118s but with a FREE

~ a —. 16K dynamic RAM board.
| When the 4118s become
available, Nascom 2
- purchasers can have them
atthe special price of £80
+ VAT forthe 8K.
So, for £295 plus VAT

this Is what you get:
MICROPROCESSOR @ Z80A which willrun at 4MHz
MEMORY butis selectable between 2/4 MHz.
@ 16K RAM board HARDWARE @ Industrial standard 12" x 8" PCB, through
(expandable to 32K). hole plated, masked and screen printed, All bus lines
® © 8K Microsoft BASIC. are fully buttered on-board
AS-SYS 1

eAneS INTERFACES @Licon57 key solid state keyboard,

Me 1K Video RAM @ Monitor/domestic TV intertace.
@ 1K Workspace/ @ Kansas City cassette Interface (300/1200 baud) or

User RAM RS232/20mA teletype Interface.
@ Malin boardsockets The Nascom2 kitis supplied complete with

for the 8x4118s or construction article and extensive software manual

2708EPROMS. for the monitor and BASIC

NQasCO

12° x8" PCB car

ca, Q
executing 158 Pable of

'NStructions inc}
all 8080 code uding

REVOLUTIONARY TOUCH
ACTIVATED KEYBOARD. A

W/<

¢ Fully built and housed in
a stylish enclosure for just

4 :
AS 3 ‘ = plus VAT.
yaArvall\)a) nterfaces with all micro
Spaces computers.

“ae
— ie he a

Designed and manufactured by TASA Inc of
California, the TASA keyboard is a truly solid state
system that has no moving parts and is virtually
indestructible. Totally flat and measuring just
0.325" thick, 6.25” deep, 15.05” wide, the TASA
has full 128 position 8-bit ASCII output plus
continuous strobe, parity select. The touch
sensors are sealed in tough polycarbonate whic
is washable and can withstand rugged treatment
in harsh environments.

Other features Include:

@ Built-in electronic shift lock.

The Nascom IMP (impact
Matrix Printer) features are listed below: . |

OF \
® 6Olines per minute. e 80characters
per line. @ Bi-directional printing. ORDER FORM
@ 10tine print buffer.e Automatic CR/LF
@ 96 character ASCII set Send your orders to: ;
(includes upper/lower case. $,#, £) Interface Components Ltd, Oakfield Corner,

Sycamore Road, Amersham, Bucks HP6 6SU.

a
c
@ Two-key rollover to prevent accidental two-key © Accepts 85" paper (pressure feed). t
operation (excluding “control” and “shitt”). © Accepts 9}" paper (tractor teed). & Tel: 024035076. Telex: 837788. PC/1/80
@ Electronic hysteresis for firrn “feel @ Tractor/pressure feed @ Description Quantity | Price
@ Signal activation time of 1 millisecond. © Baud rate from 110 to 9600. a |
@ Output via 12-way edge connector. @ External signal for optional | ==
@ CMOS compatible with pull-up resistor. synchronisation of baud rate. T _—= — =il. a
@ Parallel output: active pull-down, direct TTL © Serial RS232 interface with parallel BE
compatible (one load) open collector type. option avaitable soon. a as _ =} i _e
: |
MEMORIES a | | ‘s
MICRO MAR 21L02 £1.20each NASCOM FIRMWARE LJ a 7 1 7 a ae
IC SOCKETS 4027 £2.75 each NASPEN: £25.00 + VAT +30p P+P a VAT at 15%
8 pin ; Wpeach 4116 £7.50 each ZEAP 2: £50.00 + VAT + 30p P+P a = 4.
14 pin 12peach 2114 £4.00 each NAS-SYS 1: £25.00 + VAT + 30p P+P | P4+P
16 pin 13p each 28 Vv B
20 pin 25p each ater aces £12.50 each NASCOM HARDWARE a Totalenclosed |
elt 30peach 143881 (PIO) ..£7.50 each Motherboard: £5.50 + VAT + 50p P+P
28 pin 35p each ) a
ag On 40p seach MK3882(CTC)...£7.50each Mini Motherboard: £2.90 + VAT +50pP+P g jame
ce vouraceaecutaron I 2B opisaatiowwuares-r &
EPROMs 2708 ...£9.00each SPECIAL OFFER oo B Address ms
EPROMs 2716 .£32.00 each LM309K. 90p each NASCOM SOFTWARE |
Add VAT and 300 P- Pto allorders 8K BASIC tape: £15.00 + VAT mains i‘
ZEAP 1 tape: £30.00 + VAT + 50p P+P @ Access/Barclaycard No: ;
VISIT OUR NEW SHOP ZEAP 2 tape: £30.00 + VAT + 50p P+P «Cheques & P/Os made payable to Interface Components Lid.

e Circle No. 274
146 PRACTICAL COMPUTING January 1980

REESE a eS es sens 10S Sa" amen

A PRACTICAL
GLOSSARY

Continuing the terminological gamut with P

Pilot

A language which was designed for
writing Computer Assisted Instruc-
tion programs, aiming to overcome
the shortcomings of languages such as
Fortran and Basic which are not
designed to deal with text in a

flexible, interactive way. Some
languages with text processing
features, like PL/I, are not

commonly available to the teachers
who need to write CAI programs,
and they are troublesome to learn.
Most CAI’ programs have been
written by professional programmers
on large machines and that creates
obvious barriers. Pilot is a simple
language anyboby can use which can
be Implemented on a wide variety of
machines. It is inexpensive and it
works. (See PC, Nov. ‘78, pSS).

Pins

Connector pins are the legs on a chip
(qv). They connect the chip to the
electronic circuits on a circuit board;
they fit into pre-defined holes and are
soldered there, the solder making
contact between the circuit and the
pin. ;

You'll also have ‘pins’ inside a
plug,of course. They do much the
same job; as with mains electricity,
the plug pin fits into a socket to make
a connection.

PL/I

An interesting failure. PL/I is an
immodest acronym for Programming
Language/| and it was designed by
IBM to combine the business dp
virtues of languages like Cobol with
the scientific capabilities of Fortran
and Algol. The result is by no means a
bad thing but it has never displaced
the others. Big IBM installations make
heavy use of it but even there IBM
Assembler, Cobol and Fortran dre
utilised more widely.

The trouble is that it needs a good
deal of memory and plenty of re-
learning, so it never appealed to the
mass market of small
users, and it was never adopted over-

computer

enthusiastically by programmers who
could make a living more easily with a
different language.

PL/M

An Intel programming language
designed for use’ on development
systems.
assembler and probably qualifies as a
high-level language. There is no
connection with PL/I.

Easier to use than an

PLA

Programmed logic array. A kind of
sub-microprocessor. A PLA is an LSI
chip which can read several inputs to
deduce which of several alternative
outputs it should produce. You'll be
safe sticking to PLA as Port of
London Authority.

Plasma display
A microscope slide of blood.
Alternatively see gas discharge.

Plotter
A device which draws things
automatically; it could be a graph, a
picture of a man with cloak, tall hat,
beard, a fizzing bomb labelled BOMB.
Plotters are sometimes called any
or all of graph, digital, incremental or
X-Y plotters. They all work by
receiving digital information from the
computer, converting it into X-Y co-
ordinates for a pen — or ink-jet gun,
in more esoteric devices — and
moving the pen across the paper in

minute increments and in the
direction specified.

Plugboard

Also known as patchboard — very
occasionally — or patch panel,

sometimes Jack panel. A plugboard is
simply a circuit board, which may or
may not have circuits printed on to it,
with sockets for removable plugs
(jackplugs). Switching around the
plugs can alter what the computer
does, so plugboards are normally
utllised only for diagnostic use by a
maintenance engineer.

Plug-compatible

Something is plug-compatible if It can
plug straight into something else,
which in computer terms means it
must meet all the electrical, logical
and mechanical requirements of the
‘host’. Typically an independent
company will develop and sell plug-
compatible add-ons — like terminals
or disc drives or memory boards —
which fit on to a popular computer,
like the TRS-80 or Pet or PDP-1) or
{BM 360/370.

They may well be cheaper and
better than the computer manu-
facturer’s own products, or there
may be no alternative offering from
the computer vendor.

PMOS
Or P-channel. An older alternative to
N-channel MOS. A fabrication

PRACTICAL COMPUTING January 1980

method for MOS semiconductor
circuits; it is slower than NMOS.

Point of sale
This describes the
money changes hands In a shop of
some sort. Ordinary cash registers
are belng replaced by clever devices
which do everything the till does but
also collects information about the
sale — what has been sold and how
much for.

This might be stored on a cassette
and removed at the end of the day or
it might pass the information directly
to a computer. Either way the
information is processed by
computer to provide almost instant
notification of matters like sales
income and stock position.

locale where

Point to point

In computer terms it means a circuit
connecting two and only two things
— like a computer and a terminal —
without the intermediate assistance
of something else, like a computer.
Compare multi-point connections,
where several terminals attach by
one line to one computer.

Pointer

Could be a register or accumulator
which holds the address of the next
memory location to be accessed by a
program. Could be a register which
effectively tells you which instruction
you have searched in your program.
Could be an address of part of an
instruction which defines the start
address elsewhere of something else
— a table of values, for instance.

POKE
An instruction available in most Basics
which stores integer values In a
specified memory location. For
example, POKE 65S,15360 places the
ASCII number 6S — which is the
letter ‘A’ — in memory address
($360.

Polish

Polish notation is a way of writing
Boolean algebra so that all the
operators precede all variables. There
is also a backward version called
Reverse Polish notation. Now forget
it.

Polling
A technique used in
transmission, typically on multi-point
networks where several terminals

data

are sharing one line. A program in
the computer interrogates each
terminal in turn to find out whether
it has anything to say. This happens
very quickly and, of course, it means

you meed terminals which can
recognise when they are being
polled.

Polymorphic systems

Maker of the Poly 88 personal
computer, and several derivatives,
and another of the early leaders in
the business. It has a very good Basic.

Port

A socket on the computer into which
you can plug a terminal or some
other I/0 device.

POS
Or PoS. It stands for point of sale (qv).

Precision

A neat and logical definition, which
makes a change. Since ‘precision’
means being very clearly defined, it is
reasonable that in arithmetic it
usually means the number of
significant digits In a number.

On the other hand, there is
nothing inherently clear about logic
per se; precision, you see, is
contrasted with accuracy. They are
not the same thing. Accuracy refers
generally to the number of figures
following the decimal point — the
more you have, the more accurate
your number is. Precision refers to
discrimination from a number of
possibilities; so, irrespective of the
position of the decimal point, a four-
digit numeric form allows you 10,000
possible numbers; that's exactly how
Precise you can be, no more and no
less.

Practical Computing con-
tinues its A-Z primer of
technical terminology with
Q and R in the next issues.

Be sure not to miss it —
place an order with your
newsagent now — or better
still, take out a subscription.

147

OPERATING SYSTEMS

¢ CP/M
¢ PASCAL

¢ MULTI-USER, MULTI-TASKING
¢ CAP MICROCOBOL BOS

WORD PROCESSING SOFTWARE

HARDWARE

Z-80 Processor
S-100 Bus

MAINTENANCE

e Nation-wide servicing facilities

available.

Memory Management to 512KB
5%" Floppy Discs (dbl. density)
8” Floppy Discs (dbl. density)

Cartridge Disc Drives (to 40MB)

FQUINOX

COMPUTER SYSTEMS LTD.

TAKE YOUR PICK!

LANGUAGES

C-BASIC Compiler
M-BASIC
FORTRAN-80
COBOL-80
PASCAL
CAP-Microcobol

COST OF DEVELOPMENT SYSTEMS

(including CP/M and C-BASIC)

¢ 48KB, dual5%” Floppies
¢ 48KB, dual 8” Floppies

exchange rate variation.

“KLEEMAN HOUSE”
16 ANNING STREET,
NEW INN YARD,

LONDON EC2A 3HB.
01-739 2387/9. 01-729 4460

£1675
£2495

e Circle No. 275

Advertisement Index

Abel Computer Services 24
Acorn Computers 35
Aculab 10
Adda 40
AJD 32
Algobel Computers 30
Almarc Data Systems 28, 140
Analog Electronics 120
B

Barcellos 130
Bits & Pc's 128

Business & Leisure

Microcomputers 143
Cc
Cambridge Computer Store 24
Camden Electronics 39
CCS Microhire 134
Chromasonic Electronics 144
Clento Computers 20
Comart 2g Ue Le?)
Comp Computer

Components 149, 150, 151
Computastore 26, 139
Computerama 145
Computerbits 126

Computer Retailers Association 10

CPS 136
Crofton Electronics 32
Crystal Electronics 132
D

DAMS 123
Data Systems Supplies 122
Datron Microcentre 4
Digitus 44,46
Direct Data Marketing 38
148

EMG Marketing 140
Ensign Computer Systems 25
Equinox 83,119, 148
Essex Computer Services 34
F

Feldon Audio 130
Fletcher Worthington 30
Flyde Micro Services 38
G
Gemsoft 138
GP Industrial Electronics 124
Graffcom $22
Grama (Winter) 4
Great Northern Computers 124
H

Hal Computers 36
Happy Memories 124
Harding, AJ (Molimex) 120
HB Computers 28
Henry's Radio 138
Home & Business Computers 144
1

Icarus 21
Interactive Data Systems 38
Interface 146
Intersystems 48
Intex 40
K

Keen Computers 75
Kode Services 16
L

L & J Computers 137

Landsler Software 123
Lifeboat Associates 6,7
Liveport 80
Logitek 136
Lotus Sound 20
LP Enterprises 13
LTT Electronics 22
M

Microbits 121
Micro Centre 2
Micro Computer Applications 143

Microcomputer Business Machines 17

Micro Computer Centre 132
Micro Control 12
Microdigital 76, 77, 83, 130
Micro Management 16
Micromedia (Systems) 27
Micropute 144
Microsolve 18
Microsystems ‘80 133
Microtek 28
Mills, A 34
Moxon, Dolphin & Kirby 14
N

Nascom Microcomputers I1, 29, 129

Newbear 34, 36
Newtronics 135
oO

Online Conferences 62
P

Padmede 128, 144
Petalect 13)
Petsoft 65
Personal Computers 78
Plessey 16
Portable Microsystems 31

Praameterised Computer Systems 30

Protechnic

Rair

Research Resources
Rogis Systems
Rostronics

SEED

Sirton Products
Slough Microshop
Stack

Stage One

Strute

T
T & V Johnson

Tandy

Tally Printers
Technalogics
Technamatic

Technical Book Services
Telesystems

Tempus

Terodec

Texas Instruments

Tim Orr Design
Transam

Tridata Micro’s

TW Computers

Vv
V & T Electronics
Video Vector Dynamics

Xitan

100,

PRACTICAL COMPUTING January 1980

COMP PRO Mixer

Professional audio
mixer that you can build yourself and save over £100.

| 6 into 2 with full equalization and
echo, cve and pan controls.
All you need for your own
recording studio is a stereo tape or
cassette recorder.
| This superb mixer kit has slider
faders, level meters and
i additional auxilliary inputs.
Only £99.90 plus'VAT for
| complete kit Plus FREE power
\ am || supply valued at £25.00
ol

Ideal for
DISCOS STAGEMIXING HOME STUDIOS
AND MANY OTHER APPLICATIONS

Break the language barrier £138

+ VAT

At a price equivalent to learning one
language, LEXICON offers you, English,
Spanish, French, German, Itallan and Greek.
The LK3000 comes to you with the person to
person module which contains 6 languages,
sae MoToOaw See UaE carrying case and a bat aenetor
using Its own power source which will give

Seamer ea : you Re snouts continuous use, and can easily
be re-charged from the mains supply,

wherever you may be in the world. Every additional module carries a concise

and understandable instruction book. Your deluxe carrying case has room for
two additional modules.

ETI TV PINBALL FEATURING BREAKOUT
CHIP & PCB £14.90 ALL OTHER PARTS

HITACHI PROFESSIONAL
by MONITORS 12°= f180

@ Reliability Solid state circultry using an IC and silicon
transistors ensures high reliability.

®@ 500 lines horizontal resolution Horizontal resolution in
excess of 500 lines Is achieved at picture center.
® Stable picture Even played back pictures of VTR
can be displayed without jittering,

@ Looping video input Video input can be tooped through
with built-in termination switch. © External sync operation (available as option
for Uand C types) @© Compact construction Two monitors are mountable side
by side in a standard 19-inch rack.

MODULATORS UHF Channel 36
Standard 6 meg band width £2.90
High Quality 8 meg band width £4.90 EX-STOCK

Our charges are £7 per hour plus parts.

MEMORY

On-board, addressable memory:— 2K Monitor — Nas-Sys 1(2K ROM), 1K Video
RAM (MK 4118), 1K Work space/User RAM (MK 4118), 8K Microsoft Basic (MK
36000 ROM) 8K Static RAM/2708 EPROM,

KEYBOARD

New expanded 57 key Licon solid state keyboard especially built for Nascom.
Uses standard Nascom, monitor controlled, decoding.

TN;

The lv peak to peak video signal can drive a monitor directly and is also fed to
ye on-board modulator to drive the domestic T.V,

4.0.

On-board UART lis a which provides serial handling for the on-board
cassette interface or the RS232/20mA teletype interface.

The cassette interface is Kansas City standard at elther 300 or 1200 baud. This
Is a link option on the NASCOM-2.

The RS232 and 20mA loop connector will interface directly into any standard
teletype.

The input and output sides of the UART are independently switchable between
any of the options —

el is possible to house input on the Cassette and output on the printer.

There is also a totally uncommitted Parallel 0 (MK3881) giving 16,
programmable, I/O tines, These are addressable as 2x 8 bit ports with complete
handshake controls.

CHARACTER GENERATORS

The 1K video RAM drives a 2K ROM character generator providing the standard
ASCII character set with some additions, 128 characters in all. There is a
second 2K ROM socket for an on-board graphics package which is software
selectable. Gives another 128 characters.

DOCUMENTATION

Full construction article is provided for those who buy a kit and an extensive
software manual Is provided for the monitor and Basic.

UNIVERSAL POWER SUPPLY

Suitable for Nascom I, Nascom Il, Superboard and all computers requiring
; these specifications.
+5V @3amps +12V @1amp —5V @ 500 mA

—12v @ 500 mA
Easy to construct — complete with transformer.

Our price £24.90

= 12" BLACK & WHITE
video Ee
MONITOR !
(ae
Vos We

— @ Ideal for home, personal and business computer systems
® 12" diagonal video monitor
® Composite video Input
@ Compatible with many computer systems
@ Solid-state circuitry for a stable & sharp
picture
@ Video bandwidth - 12MHz + 30B
® Input impedance - 75 Ohms
®@ Resolution - 650 lines Minimum In Central
80% of CRT; 550 Lines Minimum beyond

central 80%. Only £79 + VAT

Compucare is a company that has been set up to provide servicing and maintenance for the popular makes of micro-
computers |.e. Sorcerer, Pet, Apple, TRS80, Nascom, Compukit.
( OMPUCARE Because of the extensive range of spare parts stocked you can usually expect your micro to be repaired within 10 days for an
average charge of £14 labour.

(Part of the Compshop Ltd. Group)

Emergency 24 hour repairs can be handled for a £10 surcharge where possible.
Compukits and Nascoms unsuccessfully constructed will be charged a standard £25.

Come and visit our newly fitted showrooms where we have the largest range
of machines on demo than anywhere in the country along with an extensive
range of books and magazines.
%# NOW OPEN ALL DAY SUNDAY FOR SHOP SALES ONLY 3%
Also full range of components and spare parts now stocked
_fwe SPECIAL SERVICES: Eprom copying — 2708 or 2716 — £5 + parts

FOR ORDERING
DETAILS

Custom ROM manufacture (minimum quantity 500) — Ring for quotation

PRACTICAL COMPUTING January 1980

149

| r

i SOFTWARE NOW AVAILABLE
i ——

| TOP QUALITY RS232

150

PET COSTS LESS
AT COMP and it's

86K — Comes complete with

r= | pedigree integral cassette deck

Full manuals
supplied. Powerful 8K Microsoft Basic in ROM.

THE TRS80 (Special Scoop)
Low Priced, Ready _

Masses of software available — £499 + VAT
16K — Same as above but with new

Improved keyboard and cassette supplied

as extra, Machine code monitor on board

sO you can program in 6502 machine
code — £590 + VAT <
32K — for a little extra get 32K memo
providing greater storage Capacity tor
Programs or data — £690 + VAT

External Cassette deck for 8K, 16K of 32K — £55 + VAT
complete with cable and connector.

PLUGS INTO YOUR OWN TV
Use your own cassette
LEVEL || BASIC WITH 16K USER RAM provides you with possibly the most power-
ful micro around. All our TRS80s are fully converted to English Television Stan-
dard and include a U.K. Power Supply, Cassette Leads, Sample Tape, Level | &
Level !1 programming manuals, and special lead that enables you to connect
direct into your own television.
Special features of Level || Basic enable you to:-
— Set or reset any point on the screen — Test for the presence of a point on
the screen (these features enable easy animation) — Save or load data from
cassette under program control — File handling capabilities on cassette using
named files. — Graphics blocks as standard — design your own pictures and
many many more features for only £399 + VAT

FULL RANGE OF TRS80
|| SOFTWARE NOW AVAILABLE

|
1} TRS80 EXPANSION ysesszoueten =
| | your needs increase.
Contains sockets for
INTERFACE additional. 16K or 32K RAM and a disk controller
| for up to 4-mini-disks. Software selectable dual

| cassettes can be used. Features a Centronics

paraliel port, real time clock, and a connector for
an RS-232C interface or whatever. Requires =
Level-I! Basic. Complete with power supply.

=) | Complete with 32K RAM — £295 + VAT —_

ULL RANGE OF PETSOFT

ee ee pe

e" SORCERER SPEAKS
YOUR LANGUAGE A
A

For personal or business use. The
best value for money around.
# 512 by 256 point screen
resolution # 16K or 32K
User RAM » Centronics
Parallel Port # RS232C Serlal
3 “Port * Composite IV peak to peak video

~ output T.V. output supplied as extra. w 64
im) programmable graphics + 64 standard PET
-f graphics * 79 key keyboard including 16 key
numeric keypad. » Expansion bus for

Connection to $100 Expansion Box.
16K Sorcerer — £690.00 + VAT

32K Sorcerer — £790.00 + VAT

$100 Expansion Box — £210 + VAT

Development Pac — £70 + VAT

Processing
Pac and
Development Pac
now available.
Word Processing Pac — £70 + VAT

preeians with properly controled Subscripts Git superscripts are ecally ‘ - —

printed. The same features also provide the ability to plot business charts an

oraghs. 3 sola iae aan a. HIRE PURCHASE AVAILABLE THROUGH
— SUITS THE OEM BUYER i
Thelwide fangs pt uses ae Ge Sextet of the new Cee pale Banter HO DG E Fl N AN Cc E.
make them attractive to the systems supplier, particularly in the role o
system console/output printer. u ut paalts _ ih SEN D S.A.E. FOR APPLICATION FORM.

PET Connector — £49

The DP 8000 prints the 96-character ASCII
FF set In s|[ngle or double width at 84 lines
per minute. @ The unit operates bl-

directionally to print a 9 x 7 matrix on
multiple copy, pin-feed plain paper. @ | |
This model accepts RS-232C or current

loop serial data at baud rates switchable | |
from 110 to 9600 and Parallel Bit data In-
put at over 1000 characters per second.
@ Standard storage capacity of 256 characters @ Other features Include Out

| of Paper Detector, Top of Form Programming and Skip Over Perforation Control. I

|| ANADEX DP8000 = °",£540 «=

= : ———
; to 5
. a} | jsned ° ations:
) BF IBM SELECTRIC pctunistes ccitcat
* Full colour — UHF output * Audio cassette tape Interface * Up to 48K | GOLFBALL n
RAM on board » BASIC in ROM (graphics commands Include COLOUR = Comes complete with Interface to

i Centronics parallel standard, Switchable

ra ie PE haa ce emetic eae iy i. a a olfball heads makes this the most versatile golfball printer around. Fits the
SU AS ALI ( PO SERRIN — ELS Ca oN Bo rcerer, TRS80 Expn. Interface, Apple & ITT2020 (with parallel card extra), Pet
only £425 + VAT EX-STOCK (with special connector extra)

F eee ss

; = and any machine that has
Centronics compatable
parallel output. Control
buttons to enable you to

—=

= = |g

suspend printing while
changing paper.
Recognises control codes
to switch printer on or off.

only £690 + vat

complete with Interface and
manual. Limited supply of
converted typewriters only

735- EX-STOCK

Ring to check | Q
Availablity, + 6d - £850 + var
1 Including Interface & manual. j

characters enhances formatting, a eT |
and it ts particularly suited to the preparation of s | FO R
shipping/freight labels and materials handling tags. |

— PLOTS CHARTS AND GRAPHS | COMPUTER PROGRAMMES 10 for £4.00

SERIAL PRINTER FOR <a ||
YOUR BUSINESS aa |

— MANAGEMENT REPORT WRITING
Theipunter's 9 x 7 dot matrix

head gives the user the abillt

to produce variable text and for-

mat. These combined with the
tabulator facility are extremely

useful to users engaged in
management report writing. The
abllity to print double size

Under program control, forms may be moved in either the forward or reverse
directions in Increments of 1/6, 1/2 or 1 full lIne. As a result, mathematical ex-

@ Circle No. 309

EUROPES FASTEST SELLING ONE BOARD COMPUTER —
AS SEEN IN JUST CHECK THE SPEC’S. sal amd

WITH EXTENDED
P.E. AUGUST, SEPTEMBER MACHINE CODE MONITOR
OCTOBER 1979 MPUKIT UKIO1 “se oissessenaten

INCLUDED FREE

LOW COST SUPERBOARD IN KIT FORM

The Compukit UK101 has

everything a one board ‘superboard' should have. P A
* Uses ultra-powerful 6502 microprocessor. Simple Soldering due to clear and

Oe prame fetraahy for Steady clear picture q ‘ " consise instructions compiled by
-S.A. products wit iz frame refresh always
results in jittery displays) : t Nw Dr. A.A. Berk, BSc.PhD
* 48chars by 16 lines — 1K memory mapped video ’ ;
system providing high speed access to screen display . '
enabling animated games and graphs
* Extensive 256 character set which includes full : : NO EXTRAS NEEDED JUST HIT
upper and lower case alphanumerics. Greek symbols RETURN’ AND GO.
for mathematical constants and numerous graphic
characters enabling you to form almost any shape you
desire anywhere on the screen i
* Video output and UHF Highgrade modulator (8Mz Build, understand, and program your
Bandwidth) which connects direct to the aerial socket
of your TV. Channel 36 UHE own computer for only a small
* Fully stabilised 5V power supply including trans- outlay.
former on board.
* Standard KANSAS city tape interface providing
high reliabilily program storage — use on any
standard domestic tape or cassette recorder. KIT ONLY £21 g + VAT
* 4K user RAM expandable to 8K on board £49 ij
aul including RF Modulator & Power
« 40 line expansion inteliece socket peste elt Supply.
attachment of extender card containing 24 an =
disk controller. (Ohio Scientific compatible). Absolutely no extras.
* 6502 machine code accessible through powerful
2K machine code monitor on board.
* High quality thru plated P.C.B. with all |.C.’s Available ready assembled and
mounted on sockets. *8K Microsoft Basic means conversion to tested, ready t far
* Professional 52 Key keyboard in 3colours — soft- and from Pet, Apple and Sorcerer easy. ed, y to go to
ware polied meaning that all debouncing and key Many compatible poorer already in print. £269
decoding done in software. SPECIAL CHARACTERS + VAT
@ €Erases line being typed, then provides
COMMANDS Carriage return, line teed.
CONT LST NEW NULL RUN Erases last character typed FUNCTIONS
STATEMENTS CR Carriage Return — must be atthe endof ABS(X) ATN(X) COS(X) EXP(X)
CLEAR DATA DEF DIM END _ FOR each Iine. LOG(X) PEEK(|) POS(I) — RND(X)
GOTO GOSUB IF.GOTO | IF. THEN INPUT LET . Separates statements on a line. SPCtl) SOQR(X) TAB(!) TAN(X)
NEXT ON..GOTO ON..GOSUB POKE PRINT REAC CONTROLIC Execution or printing of alist FRE(X) — INT(X)
REM RESTORE RETURN STOP is interrupted at the end of a line. SGN(X) SIN(X)
EXPRESSIONS “BREAK IN LINE XXXX” ts printed, in USRIN)
OPERATORS oF a dicating line number of next statement to be
4 . + executed or printed. STRING FUNCTIONS
et J? NOT.AND.OR, >< .<?,>=<= RANGE 10°" to 10 CONTROLIO No outputs occur until return ASC(X$) CHRS$S(l) FRE(X$) LEFTS(XS.1)
VARIABLES made to command mode. If an Input state- RIGHTX$.I) STRS(X)
A.B.C. 2 and two letter variables ment is encountered. either another LENIX$) MIDS(XS.1.J)
The above can all be subscripted when used in an CONTROLIO is typed. or an error occurs. VALINE a
array String variables use above names plus $.e.g.A$ 2? Equivalent to PRINT

COLOUR ADD-ON CARD AVAILABLE SOON

Enables. you to choose your foreground the background colour anywhere on the screen. Flash any character on the screen at will. Full
documentation and parts in kit form.

THE ATARI VIDEO COMPUTER SYSTEM

Atari’s Video Computer System now offers more than 1300 different game

varlations and options in twenty great Game Program™ cartridges!

Have fun whlle you sharpen your mental and physical coordination.

You can play rousing, challenging, sophisticated video games, the

games that made Atari famous.

You'll have thrill after thrill, whether you're in the thick of a dogfight, screeching around a racetrack,
or dodging asteroids in an alien galaxy. With crisp bright color (on color TV) and incredible, true-to-
life sound effects. With special circuits to protect your TV.

Cartridges now available in stock:

Basic Maths — Hunt & Score* — Space War —

Video Olympics — Outlaw — Surround — Sky Diver g\
Basket Ball — Air Sea Battle — Black Jack — Breakout e
“Codebreaker — Miniature Golf.

Extra Paddie Controllers — £14.90 + VAT

*Keyboard Controllers — £16.90 + VAT

SPECIAL OFFER WHILE STOCKS LAST:

Free extra cartridge of your choice please state 1st 2nd and 3rd preference.

AIIVIVAV SS V4i JIGS GN Ga av

Please add VAT to all prices — Delivery at cost, will be advised at time of purchase. Please make
cheques and postal orders payable to COMPSHOP LTD., or phone your order quoting
BARCLAYCARD, ACCESS, DINERS CARD or AMERICAN EXPRESS number.

CREDIT FACILITIES ARRANGED — send S.A.E. for application form.

14 Station Road, New Barnet, Hertfordshire, EN5 1QW Telex: 298755 TELCOM G

Telephone: 01-441 2922 (Sales) 01-449 6596
OPEN - 10 am - 7 pm — Monday to Saturday ‘COMP COMPUTER

COMPONENTS

Close to New Barnet BR Station — Moorgate Line. (Part of the Compshop Ltd. Group)

All Systems Are Not
Created Equal

eS) ‘ =

+ [essaenesio zea)

PORTLAND HOUSE, COPPICE SID&
BROWNHILLS, WEST MIDLAND

TELEPHONE: BROWNHILLS 4321 |

@ Circle No. 310

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