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_}- Intelligent Compfiter
2WS: © £e <Z\a
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(4 Cromemco System Three
Compare these
features—
e Fast Z-80A microprocessor
— guaranteed operation at 250 nano
second cycle time, nearly twice the
speed of most others.
e S-100 bus — the industry's
standard.
e CDOS — Cromemco’s disc operating
system, includes all the facilities of
CP/M and more besides. Runs the
CP/M Users’ Library.
© 21 card slots to allow for unparalleled
system expansion, and cards for
daisy-wheel or dot-matrix printers,
analogue-digital conversion, even a
card for programming PROMs.
® The industry's most professional
software, including COBOL, Fortran IV,
16K extended Basic, Z-80 Macro
Assembler, Word Processing Package,
Data Base Management System. Each
at the remarkable price of £59 from
The professional one. ii
Our Cromemco System Three re
combines the industry’s finest hai lb
micro-com puter with the best ® Multi-user operating system —
operating systems, compilers and [IRARAe ries aeilliaaall
applications packages available. + ras unr cteacomeli tama
We'll deliver anywhere in the UK BRISA Saisie ame
and can arrange maintenance at seal
your premises. On 24 hours call-out $iiieesreeiasaecutenrnys
inch floppy discs, RS-232 interface,
if you wish. Interested? Write-or Call RARE SIRS AS le
today for our full colour brochure.
Micro Centre Telephone: 031-225 2022
Complete Micro Systems Ltd. 132. St. Stephen St., Edinburgh EH3 5AA
@ Circle No. 101
ctical
ompyting
Managing Editor
Dennis Jarrett
Editor
Peter Laurie
Computabits Editor
Nick Hampshire
Staff Writer
Kay Floyd
Production Editor
Harold Mayes
Advertisement Manager
Erica Gruffydd
Advertisement
Department
Tom Moloney
Tina Roberts
Subscription Manager
Annabel Hunt
Publisher
Wim Hoeksma
Company Secretary
Carole Fancourt
Managing Director
Richard Hease
Editorial: 01-359 8451 |
Advertising: 01-359 8151
Production and Subscriptions:
01-359 7481
Practical Computing is
published by ECC as a
subsidiary of
WHICH COMPUTER? Ltd ©
at its registered office,
30-31 Islington Green, London
NI
| and printed by
Eden Fisher Ltd,
Southend-on-Sea.
Distributed to newsagents by
Moore Harness Ltd., 31
Corsica Street, London N5 and
to specialist shops by Practical
Computing Ltd.
Subscription Rates:
Single copy: 5Op.
Subscriptions: EK,
£6 per annum
(including airmail postage).
Europe (excluding U.K.), £12;
Elsewhere in the world: £18.
Practical Computing 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
ARTIFICIAL INTELLIGENCE IN THE MICRO AGE
Introducing our exploration of the present state of artificial intelligence’ ..........:-.:s-ssesseeseeesteetesenennees 60
REVIEW I — POWERHOUSE
Is thisithemesk-topiMvicrOWfOr YOU? ....:50cs-nessosceossssaveuseessoreveosevesessvcsemgsocesstevscesseqeenaes soosopesssoveewsosssocssares 53
REVIEW II — ACORN
We test this low-cost 6502 micro ................ccccscesscccessscesscsessccessscssecsssesscesseesseneneees Wess osaadenocsocdscenscaroessecs 56
PRINTERS REVIEWED
A close look at two printers for micro-users — Anadex and Heathkit ................ccssssccccsccecsscseseeeseseesoes 57
BUILD YOUR OWN JOYSTICK
Add a new dimension to your computer ZaMe ..........sseserssrcesserecrereeeeeos Roce EEEEDE oaths senestereseseeesases 87
SELF-TEACHING GAMES PROGRAM
How to teach your processor to teach itself noughts-and-crosses..............0004: winscessshsopeacasteees coeseeee 67
THE COMPUTER SCENE IN THE NORTH-WEST
B & B CONSULTANTS AT BOLTON
Writing microcomputer software for the Corner SHOP............sscssscsseccesseesessseessossssssessensceosssssessonsesens 71
MICRODIGITAL IN LIVERPOOL
Bruce Everiss gives advice to the would-be computer shopkeeper ...............scsscesssonersdenscseseonees consaeaea 72
KEMITRON ELECTRONICS OF CHESTER
John Drury runs a board-manufacturing operation from his attic............... acceep sagneacedvevesbes eee 73
SCHOOL AIDS TO DEVELOPMENT
How a test-bed for a microcomputer was built to the specification of teachers at Priesthorpe
COmPMeNenStye RSCUOG <ccccsscssoseccscecssoussesccsctensssetassosscccstRsrectvarencscceeehsoteaysasaaaessaseets ioaasesasteosadsce ts oSceterenee® 75
MAJOR MATHEMATICS ON MICROCOMPUTERS
Fourier analysis on the Pet.............sscsscscsssseesseeseessesstseoes soeseseneeeenenegeangeecanones ease sncotoateasarentesess vareeerei Lh
NEW YORK SHOW REPORT
Our view of the National Computer Conference .........:ssscssssssssssesseseeseseees pos svesevonateMeesece Ressaetes eaeevEe is 90
THE CASE FOR A MICROCOMPUTER CENTRE
Ian Litterick outlines the benefits and Practical Computing replies ................ssccossotacsssessssessscosovseessooeee ahh
MICROCOMPUTER BUYERS’ GUIDE
Our Invaluable guide to the microcomputers available on the market ............csccssssssocssssscessssesseseeseets 122
ALL THIS AND MORE
EDITORIAL. .............:.200066 seUedsteetaseetvessadeevacces 43 PET CORNER @.0ici.:..cccssssccccsscei8 Sy aacetavensevestccens 98
More ideas for the Pet
FEEDBACK ............00005 sessseceasesesscenssenssneanenses 45
Yon es eas APPLE PUR go. sscsessssississccensdis.ct8sscoscoomen g...103
What fs happening on the Apple scene
PRINT Or eoticsescsaclsceddetenctgrsstesettsessasecpantee4O
News and views
ILLUSTRATING BASIC ............cccsscccssssssseee 105
FICTION kisesoensays.. geasseesctsnreesesss qasuseecssseevsscy 78 cara) aaa Ce OaraPA MME CoUntmueN)
CASSETTE SOFTWARE REVIEW ......ccecc-- 81 GI OSSIAIRWVES,. «2 ccicccsssocscescseessscteots cescssetisennss 129
We try new games on tape
BOOK REVIEWS ......0...ccsccssossssssssssseccsssssoeess 83
All about what to read What’s happening next
THA NID WY, "EO RUIN ererarrescetths os seiecscesoscceossieteeee 93
Tips and ideas for the TRS-80
OCTOBER ISSUE ON SALE SEPTEMBER 12
ADVERTISEMENT IN DEX.............. aseoumeess 133
PRACTICAL COMPUTING © September 1979 3
RESEARCH RESOURCES LTD.
Microcomputers for education, science and technology
Vector and SWTP
Fortran, Pascal, Cobol, CBasic, Multi-user pilot
Exclusive to RRL: Lab-Basic, Sam (Statistical analysis) A-to-D, D-to-A converters.
Showrooms at 40, Stonehills, Welwyn Garden City, Herts. Tel: Welwyn Garden 26633 (24 hours).
@ Circle No. 102
Take a fresh bite
at the APPLE II —
—try the APPLE II PLUS!
Weare proud to announce:
*
EURAPPLE have appointed the Microsense Computers division of Data Efficiency Ltd.,
the MASTER U.K. DISTRIBUTOR for the complete Cupertino produced APPLE System.
The introduction of the NEW EUROPLUS (European version of the Apple II Plus) with:
¢ AUTO-START ROM — permits direct entry on Applications Programs from disc at
switch-on, ‘reset’ protect function and improved screen editing.
e PALSOFT ROM — Applesoft on a ROM saving RAM capacity, the need to buy an
Applesoft card, and a slot.
NEW LOWER PRICE — only £830 (Black and White version).
Weare looking for qualified DEALERS who wish to sell this system to whom we offer big
discounts and many attractive, additional benefits.
CALL — WRITE — TELEPHONE NOW
Mike Brewer Bill Mercer
0442 41191 0442 48151
microsense computers
A Division of Data Efficiency Ltd.
Finway Road, Hemel Hempstead, Herts HP2 7PS.
Prices correct at press and exclusive of VAT.
@ Circle No. 103
4 PRACTICAL COMPUTING September 1979
omart
oat the specialists
-. Pa A
The complete range of North Star
computer products in both kit and
assembled form is offered by
Comart: The Horizon computer,
the Microdisk System, memory
and floating point arithmetic
board. And, Comart being S100
specialists, other items from our
computer catalogue may be easily
added to meet your requirements.
Teaching, Research, Engineering
and Commerce .... each field has
applications where this state-of-
the-art technology provides cost
effective processing of immediate
benefit.
Comart quality. Each assembled
module is final-tested by our own
engineers. Take delivery of a
computer system — plug in a wide
variety of peripherals and use it.
PRACTICAL COMPUTING September 1979
a a .
Attractive prices, good delivery
and a choice of Comart’s factory
repair or on-site service with a.
Computer Field Maintenance
contract make the acquisition of a
Comart computer a safe décision.
Find out more — ask us for the
Comart catalogue of Computers.
The North Star dual drive double-
density Horizon computer A together
with a typical kit product B, the
Microdisk system drive C and
hardware floating point board D.
Contact us direct or call your nearest Comart dealer
The Byte Shop, I!ford, Essex. Tel: 01-554 2177
Cambridge Computer Store, Cambridge. Tel: (0223) 68155
Microcomputermart Ltd., Manchester. Tel: 061-832 2269
Crayworth Ltd., Camberley, Surrey. Tel: (0776) 34044
Digitus Ltd., London W.1. Tel: 01-636 0105
Holdene Ltd., Leeds. Tel: (0532) 459459
Isher-Woods Ltd., Luton, Beds. Tel: (0582) 424851
Newbear Computing Store, Newbury, Berks. (0635) 30505
Xitan Systems Ltd., Southampton. Tel: (0703) 38740
@ Circle No. 104
comart specialists in microcomputers
Comart Ltd., P.O. Box 2, St. Neots, Huntingdon, Cambs, PE19 2AF. Tel: (0480) 215005 Telex: 32514
5
WV
Ck commodore
Autnor iad Dos!
PET
Pet 2001
From £435
NEW PET 2001 with large keyboard.
From £ 630.00
PET 2001-16N (16K RAM and New Large Keyboard) £630.00
PET 2001-32N (32K RAM and New Large Keyboard) £750.00
PET 2001-4 (Standard PET with 4K memory) £435.00
PET 2001-8 (Standard PET with 8K memory) £515.00
PET 2040 (Dual Drive mini-floppy 343K User Storage) £745.00
PET 2023 (80 col. dot matrix printer with PET graphics) £515.00
PET 2022 (as above with tractor feed) £605.00
IEEE/RS232 Serial Interface ‘A’ Output only £106.00
1EEE/RS232 Serial Interface ‘B’ Input/output £186.00
1EEE-488/Centronics type paralle! Interface £45.00
PET C2N External Cassette Deck £53.00
Interface to $100 (4 slot motherboard) £112.00
IEEE to Pet Kable £19.00
IEEE to JEEE Kable £24.00
Sorceror (My . Zain
Now with the ! Ee: inc
$100 Bus Expansion
Interface and Oual gE -
Drive min-floppy Disk ‘Dealers
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) £1200.00
Exidy $100 Bus with tnterface+Motherboard+ PSU £200.00
Exidy Mini-floppy Disk Drive (143K Storage) £495.00
CP/N for Sorceror on disk £145.00
Disk Drives
Shugart Mini-floppy Disk Drive (including PSU) £350.00
Micropolis Mini-floppy Disk Drive (incl. PSU) £350.00
Percom FD200 Mini-floppy Disk Drive {including PSU) £350.00
APPLE 11/!TT 2020
ITT 2020 incl. PAL Modulator (16K RAM) £895.00
Apple mini-floppy Disk Drive (116K Storage) £425.00
RS 232C Serial Interface for 1TT 2020 Motherboard £110.00
Parallel Output Interface for ITT 2020 Bus £95.00
Palsoft on ROM Board (extended Basic) £110.00
RAM. Upgrade (16-32K, 32-48K) £110.00
ITT 2020 Authorised Dealers
Advanced Systems
Altair, Equinox, Billings, Heath, Rair, Horizon.
Installations to include hard disk, and multi tasking P.O.A.
Software
/
Petsoft COMPUSETTES So/inece @ ceusort
Lifeboat Associates (Authorised Dealerships, Send fot Catalogues)
PILOT (for TRS 80) text orientated language £18.00
COMAC — Computerised Accounting for TRS 80 £50.00
STOCK CONTROL (TRS 80) Inventory, P/O & Invoicing £125.00
CP/M for Thee £95.00
CBASIC for TRS 80 & Sorceror £75.00
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 £0.41
CBM KIM 1 Microcomputer System £94.00
Computalker Speech Synthesis for $100 £350.00
Books — Large range of Microcomputer related books & magazines.
If vou 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
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) 425077
TRS sO
From £350
Now available:
TRS 80 Numeric Keypad
Voice Synthesizer
$100 Interface
TRS 80, 4K Level 1 payee... with 4K memory+
VDU+Cassette drive+240v PSU)
TRS 80, 4K Level II (as above but with Level II basic)
TRS 80, 16K Level II (as above but with 16K memory)
TRS 80, 4K Level I — Keyboard+240v PSU only
TRS 80, Expansion Interface with 16K RAM
TRS 80, Expansion Interface with 32K RAM
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 TRSOOS
Level IIT Super-enhanced BASIC
RSM Assemble/Monitor on Disk
MICROCHESS or SARGON CHESS Cassette/Disk
Disk Drives for TRS 80 — see Disk Drives
UHF Modulators (encased with feads for 625 lines)
RAM upgrade (4-16K, 16-32K, 32-48K}
Supplied and fitted at our premises{Kit £85) £110.00
Upgrade to increase speed 1.78 MHZ to 2.66 MHZ £13.00
Switchable selection of Level I or Level IT (ROMS required) £25.00
Automatic volume control (AVC) for CLOAD £25.00
‘Electric Pencil’ text/word processing package {on cassette) £65.00
‘Electric Pencil’ text/word processing package (disk version) £115.00
‘Electric Pencil’ keyboard mod. to give lower
case with text/word processing package. £28.00
$100 Interface for TRS 80 £375.00
‘Library 100’ — 100 progs for TRS 80 on cassette (Level Il) £39.00
Printers
TELETYPE 43 KSR £875.00 “
Keyboard send/receive Serial printer for /
PET or TRS 80
a
£435.00
£535.00
£645.00
£350.00
£325.00
£435.00
£45.00
£445.00
£45.00
£345.00
£59.00
£245.00
£160.00
£49.00
£34.00
£25.00
£14.00
£20.00
Centronics 779 parallel(friction feed) £790.00
Centronics 779 parallel printer {tractor feed) £B90.00
Centronics 701 parallet printer, Bi-directional+ tractor £1375.00
Centronics micro printer (20, 40, 80 columns selectable)
PRINTEM 879 Pinfeed (100 c.p.s., bi-directional}
HEATH WH 14
TRENDCOM 100 (40 c.p.s., bi-directional, thermal)
TRENOCOM PRINTER (thermal, interfaces extra)
£395.00
£695.00
£510.00
£243.00
£243.00
QUME or DIABLO daisy wheel seria! printers P.O. A.
Terminals
Soroc 10120 VDU/Keyboard — 80 char./24 lines £660.00
PENTLAND V1 VDU/Keyboard, 80 char./24 lines
2 page memory £550.00
Cypher CUB VDU+separate keyboard £380.00
Ansaback ‘Phonemate’ Telephone Answering Machine, voice
operated twin cassette £190.00
PRICES EXCLUDE VAT. FREIGHT & HANDLING SENDOH
‘PHONE FOR PRICE LIST & BROCHURES
JAII prices correct at time of compilation)
Directors: Or. R.V. King, BA, MIEE.
S.G. Johnson, BSc. {Hons.}
T.S. Johnson, ABIBA, ACMB, FBSC, MBIM
A.S. Barton, ACI, ABIBA, CdipAF. = J
® (0276)62506 «iin:
(0272) 425077 Telex 858893
(+ansaback during office hours)
Hours of business 9.30—5.30 Mon-Fri. 9.30—1.00 Sat.
PRACTICAL COMPUTING September 1979
Everything you always wanted
to plug into your 7?
HARDWARE APPLE or TRS- so0* SOFTWARE
DOUBLE DENSITY DISK STORAGE TRS-80
FOR THE TRS-80 DATA MANAGEMENT/REPORT GENERATOR — easily
(220% capacity of Radio Shack’s) formats disk files, allows entry, edit, delete & list of
records; and retrieves data for display or calculation on
-TRS-80 owners can now increase their on-line mass storage EN OP OnNer oe oe). ck casas oteaue.. £200.
capacity to 200K bytes. How? By using the 77 track EL ECTRIC PENCIL — powerful word processor allows full
Micropolis model 1033-11 dual drives. ; cursor movement, insert/delete, string search, block move-
Cost: only £1195 for two drives, to give 400K on-line. ment, adjustable line length, justification (on cassette) .£65.
How does it work? By writing on 77 tracks (instead of the LOWER CASE MOD KIT FORABOVE .......... £28
conventional 35) with precision head positioning. DISK BASED WORD PROCESSING PACKAGE. . £124.95
: ; ] RSM-2D DISK MONITOR — powerful system manipulates
How do | use it? TVJ Microcomputers Etc. provides you gis data, has Z-80 breakpoint routine............ £25
with a special program to let your TRS-80 DOS know there Esp.1 EDITOR/ASSEMBLER............... £29.95
are extra tracks. This program was written especially RSM-IS MACH, LANGUAGE MONITOR tape base. £23.95
by Randy Cook, author of TRS-80 DOS. DCV DISK CONVERSION UTILITY — use with TAPE-
Will the double density disk work with my Radio Shack DISK utility to save system tapes on disk (i.e.) Pencil. £9.95
drives? Yes, except of course for copying an entire 77 track UTILITY PACK 1 — a) Libloader merges from tapes _
disk to a 35 track drive. b) Renumber (spec. mem. size); Statement analysis for
debussing......... £9.95 ea. all 3 for £24.95
NEW SARGON CHESS — 16K lv Il — the 1978 champ .... £14
: : MICROCHESS 1.5 by Jennings —4K any lev....... £14
Radio Shack Voice Synthesizer for TRS 80 provides the LABRARY 100 — anvassortment of 100 programs for; . E39
ability to speak in English and limited foreign languages. 4
. ; MAZE — random maze on the TRS-80 graphics.... £14
Capable of producing 62 phonemes (sound units) that are Ack about our COMPLETE BUSINESS SYSTEM
the building blocks of spoken language. Includes audio FORTRAN IV FOR THE TRS-80! Finally, for high speed
Eeeeitlel aiid SBEAWET.. . «nate ‘calculations on your micro, MICROSOFT’s FORTRAN can
speed up those computation-bound programs. Complete
NEW package includes compiler, relocatable assembler, text
TRS 80 Printer Interface Cable — allows you to connect a" ,. aes : :
iaitel printer (eo. Centronics: 70 saree eareetato tae editor, and linkingloader. .................. £244,
0 hietlchl a whe Oe eee B/W + CBASIC for TRS-80.:5..i5i.4-6.-..- £170.
Level || Keyboard, i.e. Expansion Interface not required. NEW DOS. — LASDOSwith.corrections& enhancements €25
eee st a Si “NEW DOS+ —As above but with further facilities:- KBFIX,
NEW RENUM, Screen to Printer one step, DOS commands from
—s BASIC, Level | in Il, SUPERZAP, Disassembler, Open ‘E’
TRS 80 Numeric Keypad Mod. — Calculator Style Numerictg end of sequential file, Load and Save faster, List
Key pad which sits to the right of the standard keypad; has variables .......... 2... ee ee ee _ £49.
keys for 0 to9, decimal point and ENTER. Both Keyboards PET
activerat the same time. .: ... 5. .62 a6 . qeua er 7HS9
“JOYSTICK PACKAGE — complete with connector, soft-
NEW ware, instructiond..... £39.95 single,..... £59.95 dual.
; PVIIGROGHESS Z.0iby Jennings ...4<s i ake . 2. £14
4
Pe Shack (Microprinter for TRS Sige eo ee AGGROLOGY/NATAL PACKAGE — sophisticated otart
electro-static Printer, switch selectable RS232 Centronics computation with PET graphics £14.95
Parallel and TRS 80 BUS Interfaces ............ £245.cuRS — best graphics yet — drop depth charges on the subs
below you and rack up points. Complete adjustability for
NEW Mah. SMe VanlatlOnS. .. 66 2 ee ew ge a os £19.95
TRENDOCOM Printers for TRS 80, PET or APPLE. 40 cps, SUPER MAZE — 2 games in 1: Tunnel vision lets you travel
40/columnihermal Printer .¢ 6. 2226 ae eames £292.through the maze in perspective with graphics, also Kat’n’
TRS 80 Interface for Trendcom Printer.........., E2ZOFMOUSEChhaS@ ate: fe Die rae. Roe es) come £19.95
PET/APPLE interface for Trendcom Printer...... . £49.74 COMMON BASIC PROGRAMS on 1 tape....... £15
19 different games at........... ee? See ne
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 BS78BH
Branches at: Birmingham, Bristol, Edinburgh, Leeds, London, Louth,
Newmarket, Nottingham, Oxford, Byfleet, Wokingham.
@ Circle No. 105
PRACTICAL COMPUTING September 1979 7
NTERPRISES
Room M.0. 24
313 Kingston Road, ‘Ilford,
Essex, 1G1 1PJ, England
01-553 1001
EUROPE'S LARGEST SELECTION OF MICROCOMPUTER BOOKS, MAGAZINES AND SOFTWARE FOR 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)
Vol 3: Some Real Support Devices {without binder)
Vol 3: Some Real Support Devices Iwith binder}
Updating subscription (6 issues} for Vol 2
Updating subscription (6 issues( for Vol 3
Updating subscriptions for Vol 2 & 3
1 Updating issue (specify for Vol 2 or 3)
1 Binder (Specify for Vol 2 or 3}
6800 Programming for Logic Design
8080 Programming for Logic Design
Z80 Programming for Logic Design
More BASIC Computer Games {coming soon)
BASIC Computer Games (also see software section)
What To Do After You Hit Return
8080 Galaxy Game
SUPER-WUMPUS — A game in 6800 Assembler code & BASIC
Computer Music
Computer Rage (A 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)
Z80 Instruction Handbook
8080 Programmers Pocket Guide
8080 Hex Code Card
8080 Octal Code Card
Best of BY1E
Scelbi BYTE Primer
Best of Creative Computing Voi 1
Best of Creative Computing Vol 2
Best of MICRO (Issues 1-6 of Micro Magazine)
Z80 Assembly Language Programming (coming soon)
6502 Assembly Language Programming (coming soon)
Microcomputer 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 Management System
Scelbal High Level Language + Supplements
Basex — A Simple Language + Compiler for the 8080
Magazine Subscriptions: UK Overseas
Price Price
Subscriptions start within 3 weeks
MICRO-6502 Journal 112 issues)
Personal Computing (12 issues)
Interface Age {12 issues|
Dr Dobbs Journal (10 issues)
Computer Music Journal (4 issues}
People’s Computers (6 issues)
BYTE {12 issues}
Creative Computing (12 issues]
Kilobaud (12 issues]
Microprocessors from Chips to Systems
Microprocessor Interfacing Techniques
Z80 Microcomputer Handbook
TV Typewriter Cookbook
Cheap Video Cookbook
CMOS Cookbook
IC OP-AMP Cookbook
RTL Cookbook
TTL Cookhook
tC 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 Cumputers are Here
New Hobby Comeuters
Understanding Microcomputers and Smali Computer Systems
Instant BASIC
Basic BASIC
Advanced BASIC E
My Computer Likes Me . -. When 1 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
Voi 3: Advanced Business Programs
Vol 4: General 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, Z80 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
Magazine Back Issues:
Micro-6502 Journal
Personal Computing
Interface Age
ROM
Dr Dobbs Journal
‘Computer Music Journal
People’s Computers
BYTE
. Creative Computing
Calculators and Computers
Kilobaud {reprints only)
73
Magazine Storage Box (Holds 12)
PRACTICAL COMPUTING September 1979
SUMMER HOLIDAY BONUS: For the purchase of 2 or mote software
SOFTWARE
DISCOUNT!
Computers Plus fnc., | FMS-80 (File Management System)
Demo Pack (includes manual & demodisc) £36.00
Bidirectional driver for Diablo Hytype printers
for use on CP/M, CDOS & IMDOS systems.
BI-DIRECT Complete System
Manual only
Computer Services
£65.00
£15.00
CP/M User Library 40 Volumes (8" only) £4.00 each
Creative Computing | Pet
Cassettes: CS-1001 Logic Games — 1
CS-1002 Number Games — 1
CS-1003 Logic Games — 2
CS-1004 Graphic Games — 1
CS-1005 Graphic Games — 2
CS-1006 Conversational Games ~ 1
CS-1007 Board Games — 1
CS-1008 Sport Games — 2
CS-1201 Simulations — 1
Apple II
CS-4001 Space Games — 1
CS-4002 Sports Games — 1
CS-4003 Strategy Games — 1
CS-4201 CAI Programs — 1
CS-4301 Know Yourself
Exidy Sorcerer
CS-5001 Graphics Games — 2
OSI Challenger 1P & Superboard I!
CS-6001 Graphics Games — 3
SOL-20
Coming Soon
TRS-80
CS-2001 Games — 1 (level 1)
CS-3001 Board Games — 1
CS-3002 Space Games — 3
Each of these are £6.50
£12.50
£19.50
CS-3033 Adventure
CS-3201 Ecology Simulations ~ 1
for CP/M
CS-9001 BASIC Games, Volume 1, disc 1
CS-9002 BASIC Games, Volume 1, disc 2.
CS-9000 Both discs purchased together
These cost £12 each, or
£20 if purchased together.
On5” Ons"
Discs Discs
Creative Computing
Discs:
Operating Systems:
Name
Digital Research
CP/M for North Star
CP/M for MDS-800
CP/M on Cromemco N/A
N/A £65.00
£85.00
SID £55.00 £50.00
MAC £65.00 £60.00
TEX £55.00 £50.00
DESPOOL £36.00 £32.50
CP/M Manuals only £25.00
TEX Manual only £12.00
SID Manual only £12.00
MAC Manual only £15.00
DESPOOL Manual only £5.00
CP/M Disc only £85.00 £45.00
SID Disc only £50.00 £45.00
MAC Disc only £55.00 £50.00
TEX Disc only £50.00
DESPOOL Disc onty £32.50
STOP PRESS:
To be announced soon a Multi-User, Multi-Tasking opetating System tor
use on 280 Systems with a minimum RAM of 64K; maximum of 16M
Ram.
STOP PRESS:
More Coming
"*Please specify H single or double Density 5” discs required.
add €1.50 for Postage & Insurance; plus VAT,
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 fog Credit Card orders (24 hr answering service)
Send to address on page 1
Indicate Payment Method; and underline items required.
packages, and paying by cheque, P.O. or cash, give yourself a 10%
Information
Uniimited Inc.,
WHATSIT for North Star Horizon
APPLE 2; 48K
APPLE 2; 32K
CP/M
Diablo Driver runs 300/ 1200 baud with autoload
For CDOS
For CP/M
CP/M for CDOS Users
Program to Expand CP/M system to be
compatable with Cromemco CDOS S/W.
LP Enterprises
Michael Shrayer Electric Pencil
A) SS II for TTY etc.,
b) OS li fora DIABLO
c) TRS-80 Cassette
d) TRS-80 disc (on cassette)
WORD-MASTER
manual only
TEX-WRITER
Manual only
WORD-STAR
Manual only
SUPER-SORT
Version 1
Version 2
Version 3
Manual only
£175.00
£215.00
£75.00
Micropro
£25.00
£45.00
£15.00
£300.00
£150.00
£120.00
Northshare
** A Multi-User system for Northstar User's £32.00
Disc only
Manual only
Starfleet Orion Game for PET 8K, TRS-80
(level 2 16K)
APPLE 2; TRS-80 (24K)
£10.00
Some Common Basic Programs for PET on
cassette
with book , £15.00
Software Systems CBASIC Disc & Manual £85.00
CBASIC Disc Only £75.00
CBASIC Manual Only £15.00
Software Works On North Star Discs
Inventory — 1
Inventory — 2
Mail Room
Housekeeper
Preventative Maintenance
FIX-tT
Manuais Only
Accounts Receivable (Sales Ledger)
Disc & 222 Page Manual
Accounts Payable (Purchase Ledger?
Disc & 177 Page Manual
General Ledger (Nomina} Ledger)
Disc & 150 Page Manual
Inventory (Stock Control)
NAD (Name & Address System)
QSORT (Sort Utility)
Demo disc for SL, PL, NL, CAR, AP, GL)
Tiny-C language for 8080, Z80, 8085 systems
Manual with Source-Code
Disc containing all files
both source & object code
Automated
Simulations
£15.00
£.17.50
£50.00
£75.00
£50.00
£35.00
£75.00
£20.00
£10.00
Structured Systems
Software £395.00
£455.00
£495.00
T.B.A
£45.00
£55.00
£25.00
Tiny-C Associates
£35.00
£35.00
THIS LIST CANCEL S ALL PREVIOUS PRICE LISTS: EFFECTIVE JULY 1979
DUE TO FLUCTUATIONS OF THE DOLLAR, PRICES SUBJECT TO CHANGE WITHOUT NOTICE.
All Orders must be Prepaid ;
Total Enclosed £
.... My cheque, P.O., 1.M.O, is enclosed in Sterting on U.K. Bank
Charge to Barclaycard/Visa/Access/Diners/American Express
Credit Card No
All publications are published in U.S.A. and shipped into Britain air-freight by L.P. Enterprises. In unusual cases, processing may exceed 30 days.
Prices subject to change without notice
TRADE ENQUIRIES WELCOME
PRACTICAL COMPUTING September 1979
®@ Circle No. 106
NEW LOW BOOK PRICES AT
Microprocessora: from chips to
systems — R. Zaks — £7.95
Microprocessor interfacing
techniques — R. Zaks — £7.95
Practical sokd circuit design.
Olesky — £5.20
Some common Basic programs —
A. Osbome — £6.30
Understanding soiid state
electronics.
Texas instruments — £2.40
Microprocessor systems design.
Klingman — £14.00
Designing with TTL integrated
circuits.
Texas Instruments — £24.80
Fundamentsis and applications of
digital logic circuits — S. Libes —
£6.36
Semiconductor circuit elements —
T. Towers and S. Libes — £5.56
TTL cookbook — D. Lancaster —
£7.50
CMOS cookbook — D. Lancaster —
£7.95
T. V. Typewnter cookbook — D.
Lancaster — £7.50
Cheap video cookbook — D.
Lancaster — £5.10
Microcomputer probiem solving
using PASCAL — K. L. Bowles —
£7.84
PASCAL User Manual and Report —
Jensen and Wirth — £5.52
Best ot BYTE vol. 1— Heimers etal.
— £8.95
Best of Creative Computing vol. 1 —
AHL et al. — £6.95
Best ot Creative Computing vol. 2—
AHL et al. — £6.95
Scelbi-Byte Ponmer — Helmers et al.
— £9.95
The Best of Micro — Tripp et al. —
£6.95
The First West Coast Computer
Faire Be ronment — J.C. Warren —
£9.5
The a West Coast Computer
Faire proceedings — J. C. Warren —
£9.56
Basex — P. Warne — £6.40
Superwumpus — J. Emmenchs —
£4.80
Ciarcia's Circuit Cellar— S. Ciarcia
— £6.40
Bar Code Loader — K. Budnick —
£1.60
Tracer: A 6800 debugging program
— J. Hemenway — £4.80
RA6800ML: An M6800 Relocatable
Macro-assembler — J. Hemenway
— £20.00
The 8080A Bugbook-
Microcomputer interfacing and
programming — P. R. Rony et al. —
8080 machine ha,
programming for
Santore— £5.10
ginners — R.
Phone in your
Access/Barclaycard
Sceibi “8080” software gourmet
guide and cookbook ~— Scelbi
computer consulting — £7.95
8080/8085 Software design—C. A.
Titus, P. R. Rony et al. — £7.50
Practical microcomputer
programming: The intel 8080 — W
J. Welter et al. — £17.56
Scelbi's 8080 standard monitor£9.95
Sceibi’s 8080 standard editor £9.95
pee 8080 standard assembler
Sceiby computerconsuttants.
8080 Assembly language
programming— L. Leventhal —
£7.95
An Editor/Assembler system for
8080/8085 based computers — W. J.
Weller— £11.96
Sceibi 8080 Galaxy game — scum
computer consultants — £7.95
2-80 aoe handbook — Sceib:
—£3.9
Practical microcomputer
programming: the 280 — W. J.
Weller — £23.96
Sargon 280 Chess Program — D.
and K. Spracklen — £9.50
The 280 microcomputer handbook
— W. Barden — £6.95
A-80 Programming for togic design
— A. Osbome — £5.95
Z-80 Programming manual —
Mostek — £4.50
Sorcerer Technical manual — £8.95
Practica! microcomputer
programming: the M6800 — W. J.
Weller et al.— £17.56
Sceib: 6800 Gourmet guide— Scels
computer consultants — £7.95
Programming the 6800
microprocessor — Bob Southem —
£8.00
6800 Assembly language
programming — L. Leventhal —
£7.95
Using the 6800 microprocessor—
E. Poe— £6.25
APL — an interactive ap eas —
Gilman and Rose — £39.
Microprogrammed APL
implementation — R. Zaks — £14.75
Aguide to SC/MP programming —
Orury — £4.00
Artist and computer— R. Leavit—
£3.96
illustrating Basic — a simple
anny language — D. Alcock
— £2.25
Basic computer games — D.H. Ahl
—£5.50
Game playing with BASIC — D.
Spencer — £5.56
Starship simulation — R. Garrett—
£5.10
Game playing with computers — D.
Spencer — £13.56
57 Practical programs and games in
BASIC — K. Tracton — £6.36
Chess and computers — D. Levy —
£7.16
Chess skill in man and machine —
P. Frey ed — £11.84
V. & T. ELECTRONICS
ASSEMBLER FOR NASCOM ON TAPE £10:00
supports all standard mnemonics, occupies 33K available
in sixteen different versions, i.e. one for each page of
O to F; please state which page you require.
CONVERSION KIT TO PLACE NASCOM
MONITOR & VDU ON ANY PAGE IN MEMORY
please write or phone for details.
THIS MONTH’S SPECIAL OFFER: NATIONAL
MM5270 4Kxl 200NS CERAMIC PACKAGE
£10:00 FOR 8
21L02 450ns
21L02 250ns
4116 250ns
2114 300ns
8 off £6:00
8 off £7-00
8 off £7-00
2 off £11-50
Z80 cpu _£13-00
Z80 cpu £16-00
Z80 PIO £15-00
2716 INTEL 1 off £23-50
We apologise to our customers who have tried to contact
us at Dartmouth Rd, N. W2., but we haven't moved
yet—our address is still as below. Stuck for a bit in
the middle of the night? We are often open very late
but please phone first. If you don’t see what you need
in this ad, please phone and enquire. By the time this
ad appears, we hope to have some 8 in. floppies in at silly
prices—first come, first served.
Please add 40p postage then V.A.T.
V&T ELECTRONICS 01-263 2643
82 CHESTER ROAD, LONDON N.19
@ Circle No. 108
BIRMINGHAM
COMPUTER CENTRE
Commodore Specialists in
Authorised agents Commodore
PETSOFT DIST. Hardware
PETACT ALL MODELS
business EX STOCK
programs
2001-4K 2001-8K 2001-16K 2001-32K
e
All at special discount prices including large keyboard
Floppy dual disk drive — Printers
e
KIMI BETSI — KIMSI, etc
Cassette tapes super quality
Number on Diskettes — super qualit
051-236-0707 fam mm mm som oom com mo oes mm sg Sr ead
1 or complete t ENCLOSE:
i Now available ex stock £675 —
Camden BD 80 Printer professional business use. 2K
this order
form
CHEQUE/POSTAL ORDER NO.....................
BARCLAYCARD NO...........
PLEASE ec seaepagelataen es a character buffer
dca _.... ADDRESS... Sts | ' Si
| aie il a QN Send for free literature =—
| HP terms available ——
i re ‘ | COMPLETE ANO POST TO ee. | Showrooms open Mon to Sat, 10am-6pm
NE : ;
mer MICRO DIGIT AL LTD. 25.28UNSWICK STREET oe, | Camden Electronics (first floor) 462 Coventry Road,
con coe ane ae OOo me A ee Small Heath, Birmingham BIO OUG Tel: (021) 7738240
@ Circle No. 107 @ Circle No. 109
10 PRACTICAL COMPUTING September 1979
PET
SWTP
GRAMA (WINTER) LTD
This is how your business appears on the screen
A complete Business Program Package (version one) free with the purchase of a 32-40K computer
system.
Approx 60 entries * updates require only 1-2 hours weekly and your entire business is under
* PROGRAMS ARE INTEGRATED
1=ENTER NEW NAMES/ADDRESSES
2=* ENTER/PRINT INVOICES
3=%* ENTER PURCHASES
4=* ENTER A/C RECEIVABLES
5=ENTER A/C PAYABLES
6=ENTER/UPDATE STOCKS REC’D
7=ENTER ORDERS REC’D
8=EXAMINE/UPDATE BANK BALANCE
9=EXAMINE SALES LEDGER
10=EXAMINE PURCHASE LEDGER
11=EXAMINE ORDER BOOK
12=EXAMINE PRODUCT SALES
WHICH ONE (ENTER 1 TO 24)
control.
SELECT FUNCTION BY NUMBER
13=PRINT CUSTOMER STATEMENTS
14=PRINT SUPPLIER STATEMENTS
15=PRINT AGENTS STATEMENTS
16=PRINT VAT STATEMENTS
17=PRINT WEEK/MONTH SALES
18=PRINT WEEK/MONTH PURCHASES
19=PRINT YEAR AUDIT
20=PRINT PROFIT/LOSS ACCOUNT
21=UPDATE ENOMONTH FILES
22=PRINT CASHFLOW ANALYSIS
23=ENTER PAYROLL
24=RETURN TO BASIC
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.
THINK OF THE POSSIBILITIES, AND ADD TO THOSE HERE IF YOU WISH
Price tor above: Version 1 {excluding programs 19, 20, 22, 23) — £275 plus VAT; Version 2 (including programs 19, 20, 22, 23) — £375 plus VAT; Version 3 {including
sorts and incomplete account handling) — £475 plus VAT, or tull listing plus manual to be typed-in on most computer systems £150. Barclaycard enquines welcome.
Hardware systems tailored to your requirements (SWTP and PET) from £600 to £5,000 approx. Above package is intended to work with processor. twin-floppy
and printer. 5 x “in soft-sectored spaced disks £2.55 plus P&P.
MULTI-MODE ANDO
PET DISK USERS!!!
THE ADDRESS MODE
—EX AMINE MODE—
FUNCTION PROGRAM HAS SEVERAL FUNCTIONS. FOR
EXAMPLE:
SELECT MAIN MODALITY SELECT WHICH YOU REQUIRE 01 = NUMBER
1 = GENERAL 1 = EXAMINE ADDRESS 02 = NAME
2 = ADDRESS 2=AD2 ADDRESS 03 = ADORESS 1
3 = STOCKS 3 = AMEND ADDRESS 04 = ADDRESS 2
4 = ORDERS 4 = DELETE ADDRESS 05 = ADDRESS 3
5 = BANKS 5 = PRINT LISTING 06 = ADDRESS 4
6 = COSTING 6 = COMBINE NUMERICS 07 = ADDRESS 5
7 = PROCESS 7 = CHANGE MODE 08 = PHONENO ,
8 = RENTALS 8 = RETURN TOMAIN LIST 09 = DISC CODE
9 = DECISIONS 9 = RETURN TO BASIC 10 = AGENT NO
10 = SHARES 11 = 0 SHLASH HEAD CODE
12 = CREDIT LIMIT
WHICH? WHICH? WHICH NO?
“ALL = 99999 FINISH = 0”
Create your own modes, combine your own numerics, program requires approx. 20K bytes disk space .. ..£100
Please telephone for appointment — Tony Winter on 01-636 8210
GRAMA (WINTER) LT
PRACTICAL COMPUTING September:!979
(G.W. COMPUTERS LTD)
21B Dryden Chambers,
119 Oxford St., London W1.
®@ Circle No. 110
|
SMALL SYSTEMS ENGINEERING LTD.
(Incorporating R. BAILEY ASSOCIATES)
62 New Cavendish Street, London W1M 7LD, Tel: 01-637 0777, Telex: 8813085 Abacus
SUPPLIER OF PET MEMORY BOARDS AND
INTERFACES THROUGHOUT EUROPE
IEEE-488/RS232C SERIAL INTERFACE
—Full IEEE address decoding, RS232C or 20mA loop output, NOW AVAILABLE COMPUCOLOR II MODEL 3
—Switch selectable Baud Rate, Crystal controlled Baud Rate timing, i :
—Boxed units complete with connectors, full operating instructions —13in. 8-colour CRT. 8080 Microprocessor.
and sample programs supplied —16K extended disk BASIC in ROM.
—Lower Case Printing | —71-Key detached keyboard.
—Serial Interface B, input and output... . £186 —8K RAM memory for user programs.
—Serial Interface A, output only .. . . £106 —64 characters per line by 32 lines per page.
IEEE-488/CENTRONICS TYPE PARALLEL INTERFACE : : F A
Low cost unit without IEEE address decoding —Special graphics package with 128 x 128 point
Also suitable for Anadex DP-8000 Printer... . £45 plotting.
ANALOG INPUT/OUTPUT* —Built-in mini-floppy disk drive.
—IEEE-488, 16 Channel, 8 BitA-D .... £300 —50 pin bus.
—lEEE-488, 8 Channel,8 BitD-A.... £400 —RS-232 1/O port for serial printers, etc. . . £1,390
PET INTELLIGENT TERMINAL SOFTWARE PACKAGE
A software package which, in conjunction with an Interface B P & T 488 S-100 IEEE-488 INTERFACE
—lInterfaces S-100 computers to the |EEE-488
F F i - instrumentation bus.
Wiles li ala —Functions as a 488 controller, talker or listener.
PET MEMORY BOARDS —Three software packages available:
internally mounting memory boards available in 2 configurations North Star DOS/BASIC interface CP/M interface.
—24K ... £328 -32K... £432 Custom. systems interface £325
NEW MULTIPURPOSE UNIDIRECTIONAL IEEE-488 Sa ee
INTERFACE
Addressable * Pet floppy disc unit compatibility * : j
Code conversion facilities included * Custom units TERMS: All prices EX. VAT. Please make
may be supplied with special code sets * Serial C.W.O.
Version: switch selectable Baud Rates up to 9600 Cheques payable to SMALL SYSTEMS
Baud & 2 printer busy input, both RS232C & 20MA ENGINEERING. Post and Package (includes
ANADEX and PR&O Printers, £120 SECURICOR express delivery) £5.00. All
goods supplied under 90 days warranty.
*All enquiries on analog I/O ring 01-387 7388
@ Circle No. III
MICRO MEDIA SYSTEMS
CONSULT THE EXPERTS
Announcing COMPUCOLOUR II
Plus — EQUINOX 300 — CROMEMCO — PROCESSOR TECH. SOL. — NORTH
STAR HORIZON. — COMMODORE PET. — MICROSTAR 45.
We supply a complete range of peripherals to suit the range listed, including Texas, Elbit,
Teletype, Diablo, Adds, Cifer, etc.
(O.E.M. terms available). Send S.A.E. for our Booklist.
Accounting suites — Payroll — Mailing list — Hotel package — Pert — Perspective drawing —
Simplex linear programming — Planets (Management Game) PLUS A COMPLETE BESPOKE
PROG. SERVICE.
WE ARE CURRENTLY RUNNING A SERIES OF ONE DAY SEMINARS. RING US FOR DETAILS.
Micromedia Systems, 14 Chepstow Road, Newport, GWENT. NPT 8EA.
Tel: (0633) 841691/50528/63310.
@ Circle No. 112
12 PRACTICAL COMPUTING September 1979
THENEW STANDARDIN
MICROCOMPUTER
POWER
SIMPLICITY. SOPHISTICATION.
Apple II Plus
APPLE-I| 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. APPLE-II PLUS is appealing and
comfortable (like other appliances that make your life
easier), and it brings to personat computing a new level
of power through hardware and software
sophistication.
The APPLE-1I PLUS is faster, smaller and more
powerful than its predecessors, and it's easier to use
too, because of advanced, built in features like:
“PALSOFT
A fast, extended 10K BASIC with 9-digit precision and
graphics extensions
“HIGH RESOLUTION GRAPHICS
Ona matrix of 280X192 individually addressable points.
*“AUTO-START ROM
With power on boot of application 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.
Apple Pascal
APPLE PASCALTMN is the new extension to
microcomputer power.
PASCALTM incorporating UCSD PASCALTM, offers
extended features in a complete interactive package
employing today’s 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.
“EDITOR
A fast, screen-oriented editor for program development
and word processing applications.
“COMPILER
Standard PASCAL plus full set of extensions for
Strings, disc flles, graphics and system programming.
Hi-res graphics “Turtlegraphics’: as originated at MIT.
INIT turtle. PENCOLOR, TURNTO, TURN, MOVE,
TEXT GRAF.
GOTOXY procedure for cursor addressing
FUNCTION Keypress tells whether character available.
Library routines include: RANDOM, RANDOMIZE,
PADDLE, BUTTON. TTLOUT. KEYPRESS etc.
"RELOCATABLE ASSEMBLER
Permits relocatable assembly language routines to be
generated and linked to Pascal programs.
“SYSTEM UTILITIES
Includes desk calculator-performs basic calculations
and parameter — allows examination and modification
of system environment.
25 BRUNSWICK STREET, LIVERPOOL L2 OBJ.
Mail Order: 051-236 0707 Other Departments: 051-227 2535
PRACTICAL COMPUTING September 1979
Floppy Disks
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.
Features
* Storage capacity of 116 kilobytes/diskette.
* Date transfer rate 156K Bits/second.
* Individual file write protection.
Powered directly from Apple Il.
* Fulldisk capability with systems as little as 16K bytes of
RAM.
* Fast access time — 600 m sec (max) across 35 tracks.
“ Powerful disk operating software.
* Load and store files by name.
* BASIC program chaining
* Random or sequential file access.
Fioppy Disk Subsystem
Vat
63.75
Second disk drive and connecting cable
375.00 56.25 431.25
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 buiit into the card, to eliminate
user programming requirements.
Nett Vat Total
110.00 16.50 126.50
Communications Interface Card
Allows your Apple to “taik” (though a modem) with
other computers and terminals over ordinary telephone
an load programs over the phone, send messages to
remote terminals or access your office computer trom
the comfort of your home.
Communication interface Card
Nett Vat Total
110.00 16.50 126.50
High Speed Serial Interface Card
Allows Apple to exchange data with printers, plotters
and computers in serial tormat at up to 19.2 K Baud
High Speed Serial Interface Card
Nett Vat
110,00 16.50
Speechlab Voice
Card
Allows the Apple to recognise a spoken vocabulary of
up to 32 user-selected words. The computer can be
programmed to perform any task desired upon
recognition of a key word.
Volce Recognition Card
Vat
Nett
425.00
Total
488.75
Total
126.50
Recognition
Nett
Prototyping Card
Provides the User with a means of building up
experimental circuitry forthe Apple computer. The 23,"
x7" double-sided board includes a hole pattern that
accepts all conventional integrated circuits and passive
components. Documentation includes a compiete
system bus description to aid the interface designer
Prototyping Card
Nett Vat.
18.00 2.70
Carrying Case
The Apple is truly portable and this padded viny!,
leather look case protects your Appie in transit and
makes it easler to carry.
Carrying Case
Vat
3.75
Apple Pascal
System
A recommended configuration for developing and
using Pascal application programs
APPLE-II PLUS, 48K RAM
FLOPPY DISK system.....
PASCAL extension card
Apple Soltware Bank Vols. 1-5 (S disks} FREE
Other Prices
8x 4116 RAMS 16zk Bytes
Joystick .
Oisketles ...
10 C13 Cassettes
Oolphin 8.0. 80...........
TRENCOM-100 Incl. interlace
AXIOM micro Printers .
AXIOM graphics Printers
Books
Apple operators manual
Applesoft extended
Basic manual .
Basic tutor
6502 Pragismmlng manual .
6502 hardware manual
PART EXCHANGE
Apple
wners’, trade uptoan
re MICRODIGITAL. We can alow
up to £300 tor your old on
against the cost of anew Apple tl.
Total
20.70
Nett
25.00
Total
28.75
£950
. £425
Ring lor price.
NO VAT ON
THESE
ITEMS
grey
@ Circle No. 113
13
JUST AVAILABLE !!
Does your computer speak to you?
“WEHL IHT KAAN DOO WIHTH MEE!’
Features Make your computer
@ Single PCB plugs directly talk
into an SWPTc 6800 bus. ie 2 ee phonetic
ext (as in the sentence at
e pee rae vocal tract the top of the page).
* Microspeech with the
@ Realtime software MSP2 software can make
converts any stored your computer speak.
phonetic code to speech. MSP2 uses only 4K of
@ Computer Games. memory. Every extra 1K
@ External input for special of buffer space can store
musical effects. 90 seconds of speech.
TRENDCOM 100
Intelligent Printer
40 character per second rate
Quiet operation
96 character set
Microprocessor controlled
Bidirectional printing
High reliability
Clear 5 x 7 characters
40 characters per line on 4%" thermal paper
SMO sore Weight 7lb.
era oe
—
és ie
existing BASIC programs.
Microspeech package a’ &
@ Speech synthesizer board . -8 ge 6 ®
(assembled & tested). a we
:
@ MSP2 Software on floppy ere tt tT
disc or cassette.
@ Hardware & Software :
Reale It speaks for itself
@ Speaking BASIC software
option.
TIM ORR DESIGN COSTRONICS
CONSULTANT ELECTRONICS
55 Drive Mansions, 13 Pield Heath 7, Amersham Hill,
Fulham Road, Avenue, Hillingdon, High Wycombe,
_———
London, SW6 Middlesex | CM L
@ Circle No. 114 \\ — Tel: High Wycombe (STD 0494) 20416
@ Adds speech output to c<?
a
Trendcom 100 £243
Interface for Pet, Apple £49
Interface for Sorcerer, TRS80 £29
Thermal paper (2 rolls x 80ft) £5
Add VAT @ 15%, £2 for delivery
Cash with order to:-
Chiltern Microcomputers Ltd.
a
Bucks 11P13 6NQ
.
|
!
@ Circle No. 115
Select Pet, Apple or Nascom in West London.
Choosing the computer most suitable for
your needs can be difficult at the best of times.
And when it comes to the final selection from today’s
three top-value micros it doesn’t get any easier
We won't promise to make your decision for
you, but a combination of your requirements and
our professional expertise will ensure you get a
system that's right for you.
So why not drop in to discuss your personal
computing needs with us? Naturally we can
arrange a demonstration, but better still try a
machine yourself.
When you’ve chosen your hardware
remember that’s not the end of the tale. We can
provide software packages, tailored business
systems and even games. Plus of course systems
and programming support, maintenance and finance.
Adda Computers, 17-19 The Broadway, Ealing,
London W5 2NH. Telephone: 01-579 5845.
Open 09.00-18.00 Monday to Friday.
10.00-16.00 Saturdays.
adda
we add up toa great deal,
@ Circle No. 116
14 PRACTICAL COMPUTING September 1979
Get it right...
The right machine PE'T
The right programs
Computastore
PAYROLL This flexible PAYROLL system
makes wage calculation fast, easy and accurate. It
prints payslips, totals, coin analysis, and year end
totals. Updates for tax and NI changes available.
PETE Go on-line with this unqiue software
package which turns your PET into an intelligent
RS-232 terminal with user definable transmission
. parameters.
ASSEMBLER Really fast Assembler written in
machine code, assembles up to 500 lines per
minute on the Commodore Disk. It allows 200
symbols on an 8K PET (1000 on larger PETS).
Computastore
Software that means business
‘PRACTICAL COMPUTING § September 1979
,ORE
o An,
DISASSEMBLER Can even display the PET’s
ROMs, and search them for strings of characters
or patterns af hexadecimal. bytes. Outputs to
screen or printer.
KEYBOARD Big keyboard terminal or printer
(e.g. TTY 43) can now be used as a dumb terminal
for keying in BASIC programs or data for your
PET. The PET can even be in a different location!
Also, speeds up data entry for 8K PET owners
with keyboard/printer.
Cassette and Commodore Disk versions
available for old and new ROM PETs.
DUST,
COVERS
£3 each
7]
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. 117
15
4096-16
4116-3
4118
74188AN
(300ns)
(250ns)
4K x 1 DRAM -00
16K x 1DRAM -00
1K x 8 SRAM -50
256 bit PROM -00
2708 (450ns) 1K x 8 EPROM “50
2-80 CPU 4 MHz -50
2-80 PIO -50
CMOS p CMOS
4000 -15 4024
4001 -15 4025
4002 -15 4027
4007 -15 4028
4011 -15 4029
4012 -15 4040
4013 -26 4042
4015 -76 4043
4016 -28 4044
4017 -57 4046
4018 -65 4047
4020 -67 4049
4021 -67 4050
4022 -65 4051
4023 -15 4052
CMOS p
4053-51
4060 -94
4066 -33
4068 -15
4069 +15
4070-15
4071-15
4072-15
4073-15
4075-15
4076 -73
4077-15
4078 +15
4081 15
4082 -15
4093-39
P&P 30p
All prices
include VAT.
Access Cards.
Welcome.
STRUTT ELECTRICAL & MECHANICAL
ENGINEERING LTD.
Telex 45263
3C, Barley Market Street,
Tavistock, Devon, PL19 O5F.
Tel: Tavistock 0822 5439.
@ Circle No. 118
World’s widest range of micros
from the UK’s specialist importers.
C1iP & Superboard — better keyboard than PET!
better BASIC than TRS80! cheaper than either!
From less than £300.
C2-4P also has better display and graphics than
PET or TRS80! C2-8P worlds most expandable
" personal computer. From less than £600.
Software over 60 personal, business, games &
educational programs on cassette or minidisc.
Expansion — up to 32K (48K C2-8P), I/F boards
for printers, D/A converters, prototyping boards,
voice I/O, sound and AC control option (C2 only).
SMALL C30EM, C381, C3A, C3B, C3C — real business
BUSINESS | systems starting with 32K & dual 8" floppies,
Ny) Expandable to multiusers, 20 or 75MB hard discs,
¢ Of * BASIC, FORTRAN, COBOL RPG11. Applications
Ved software and DATA BASE MANAGEMENT
Nee oF 2 PACKAGE.
WW?-4 | From £3250-C30EM, £12,350 with 75MB disc-C3B.
Phone for details or to arrange demo!
U-MICROCOMPUTERS
U - Microcomputers Ltd
PO Box 24, Northwich, Cheshire CW8 1RS
Tel: 0606-75627 Telex: 666592 ¥
@ Circle No. 119
U-Microcomputers are an official Ohio importer
Some dealerships in N. & Midlands stil! available
Now youcan hire before you buy at noextra cost,
at last you can be sure that the machine you buy,
is the machine that best suits your needs. You —
may hire a microcomputer system for as little as
| £5.00 aday, peripherals availableinclude, floppy |
disk units, colour and monochrome TV's, cas-
sette recorders, etc.
Each machine is supplied with a selection of
relevant software. Delivery is free if within the
Merseyside area, otherwise charged at cost.
N.B.
The hire charges can be deducted from the cost
of anew machine, no matter which machine you
eventually purchase.
Please send for our free Price List.
25 Brunswick Street, Liverpool L2 OBJ
For further details and booking
Ring: 051-227 2535 (Paul Fullwood)
@ Circle No. 120
EXIDY INC.
SORCERER
COMPUTERS
EDUCATION
Exidy Sorcerer
8K-£702 16K-£820.80 32K-£927.72
$100 Expansion Box 6-slot-£226.80 _
Micropolis Dual Disc Drive—£1,296.00
Centronics Printer-£864.00
PET 2001 House Trained
PET 2001 4K-£496.80
8K-£594.00
16K-£729.00
32K-£858.60
INTERNAL MEMORY EXPANSION BOARDS AVAILABLE
NASCOM 1 kit £178.20 or Built & Tested £232.20
3A Power Supply kit £21.50 or Built & Tested £26.50
Ohio SUPERBOARD II 8K Basic Built & Tested £284.95
CHESS CHAMPION 6-level Chess Computer £89.50
STARCHESS Colour TV Game (Space Age Chess) £64-96_ £59.50
ELECTRONIC MASTERMIND Pocket-size 3, 4 or 5 Digits £14.90
TRS 80 LIBRARY 100-100 Programs on Cassettes £46-95
2K BASIC for NASCOM 1 used in place of Nasbug or B-Bug £22.00
SAE with all enquiries — All price inclusive VAT
DUAL DISC DRIVE
FOR PET
£989.28
SUPPLIERS TO BUSINESS, EDUCATION & HEALTH AUTHORITIES
27 Sidney Road, London N22 4LT
01-889 9736
@ Circle No. 121
PRACTICAL COMPUTING September 1979
Ra
rPrPey Fs
ewewrveyere fe
ARM ew eae e tf
se
-—~rwvwovwvene
DETAILED SPECIFICATION
MODEL VDP 10
VIDEO
— One page memory
64 characters per line 16 lines per page
— Full 128 ASCII character set
96 upper and lower case characters 32 control symbols
— Comprehensive cursor controls
Left/right/up/down CR/LF Clear/home/line-erase
— PROM translation of inbound characters, giving:-
Programmable coding for cursor commands
Programmable display control for each input code
— Cursor command codes can be displayed using:-
‘Display’ key for protocol debugging V24 input bit 8
under remote software control
— European compatible composite video out for:-
TV monitor, or Modified TV set.
Vv28 1/0
— High/low rates externally switchable and jumper selectable
from:-
9600/4800/2400/1 200/600/300/150/75 bits/sec.
220/110 bits/sec. (NOTE: at high receive speeds, remote
software should allow 8.3 ms for CR, LF and 132 ms
for Clear)
Odd, Even or No Parity Full duplex or local mode
One or two stop bits V24 serial |/O using standard 25 pin
socket
KEYBOARD
— 72 key ultra-reliable solid state contactless keyboard
— Standard ASCII layout plus programmable cursor control
keypad
— QWERTY standard
— Full N key rollover
— Caps Lock with LED for TTY compatibility
— Repeat key.
MAINS POWER SUPPLY
— Built-in — needs 220-240V 50Hz.
PRACTICAL COMPUTING September 1979 .
DATA PRECISION [Equipment] Lid.
provdiy present
THE
VIDEO
HETBORRU
— 72 key ultra-reliable contactless capacitive keyboard
with cursor command keypad :
— RS 232/V24 serial 1/O up to 9600 bauds
— Composite video output for monitor or modified TV
— Built-in mains power supply
Although low-cost, the Video Keyboard is OEM built
in the UK using only top-quality components. Other
low-cost products use cheap, low MTBF contact-switch
keyboards. The Video Keyboard uses the same pro-
fessional quality ultra-reliable contactless keyboard
used by top-flight UK terminal manufacturers.
CABINET
— Tailor-made to house all. electronics, keyboard, video and
V24 sockets, switches and power supply.
SWITCHES
— Power on/off
— Ond-ine/Off-line
— Baud Rate Select
Medium/High/Low
— Display Key
Displays control characters for easy protucol debugging
Normally set to 9600/1200/300
AVAILABLE IN TWO VERSIONS (Monitor/converted TV not
included).
Complete Video Keyboard £230+VAT (UK p&p paid)
Stripped Video Keyboard ..... £190+VAT (UK p&p paid)
Istripped version excludes case, case hardware (switches,
plugs), 240/9-0-9 VAC transformer but otherwise complete
and tested} .
Both versions are brand new with comprehensive manual and
12-month warranty.
DATA PRECISION (Equipment) LIMITED,
81 Goldsworth Road, Woking, Surrey GU21 1LJ
Tel: Woking 64444/67420 Reg. in England No. 913775
Please send me:
. Complete Video Keyboards @ £264.50 each, inc. VAT
and UK postage and packing
.... Stripped Video Keyboards @ £218.50 each, inc. VAT
and UK postage and packing
. Video Keyboard Manuals @ £2 each, inc. postage and
packing (free with Keyboard)
LI | enclose my cheque
L) Charge to my VISA/ACCESS/DINERS Card ¢Not VISA
LILLMlititiitt |
Name. .
Adaress. . .
Signature.
@ Circle No. 122
1?
i=)
GODBOUT Computer Products
Alpha Micro/Altair/Cromemco/Imsai/North Star/Polymorphic,
etc. S-100 Bus computer compatible memory and other pro-
ducts.
NEW LOW PRICES ON MEMORY, e.g.—
' Kit Ass.
Econoram IV, 4MHz, 16K bytes £150 £169
Econoram VII, 4MHz, 24K bytes £230 £249
Econoram XIil, 4MHz, 32K bytes, bank select £315 £339
EXTRA LOW PRICES ON QUALITY DISKS
(Verbatim, Scotch, Memorex, etc.) Diskettes stocked for most
micro-computers: :
Apple, Cromemco, Tandy, Vector Graphic etc. (soft sector
mini)
North Star, Polymorphic, Wang etc. (10 sector mini)
Altair, Micropolis etc. (16 sector mini)
ISKS ‘ LTT : MEMORY : DISKS : LTT : MEMORY : DISKS : LTT: MEMORY
START
ARE YOU ABOUT TO
BUY A'PET' ?
MAKE A NOTE OF OUR NUMBER:
YOU NEVER KNOW...
DO YOU LIVE WITHIN
‘50M OF NW LONDON
DO YOU WANT TO PAY
THE LOWEST PRICE?
THE NATIONAL DEBT NEEDS
PEOPLE LIKE YOU...
yes
ARE YOU ONLY FREE no WE ARE OPEN NORMAL HOURS
AFTER NORMAL HOURS Too!
yes fe
| YOU ARE EN-ROUTE TO
L&J COMPUTERS
JUST FOR STARTERS ore
PET 2001-4 £419 + vat
PET 2001-8 £499 + vat
PET 2001-16 £599+ vat
PET 2001-32 £725 + vat
WE ARE OPEN ALL HOURS
OUR PRICES ARE THE
LOWEST IN THE U.K.
MAIL ORDER: OR
MOVE NEARER!
DEC, Cromemco, Prime, etc. (soft sector floppy, 8in.)
Eh eee - + PRINTERS
Pack of ten disks, £19. Carton of ten packs (100 disks), £175 RNa ainooneee +FLOPPIES
hewitt + SOFTWARE
' . + INTERFACES
| | r
WE ACCEPT VISA EXTRA SPECIAL OFFER THIS
ACCESS: BARCLAYCARD MONTH:
CARD BACKED CHEQUES
CASH PET 2001-8
FOREIGN CURRENCY +CENTRONIC 779 PRINTER
+ INTERFACE
ALL FOR £1290 ¢ vat t
DON'T DELAY - YOU WORK OUT THE SAVING !!
PHONE J
TO-DAY!
All prices given include postage and packing (overseas add
£10). Just add VAT (presently 15%). Send 9p stamp for
details.
Quantity discounts available on application. Credit terms (nett
30 days) given to large companies and government establish-
ments.
LTT ELECTRONICS
8 Waldegrave Road
London SE19
Mail Order ‘phone: 01-828 1785
LTT : MEMORY : DISKS : LTT ;: MEMORY :-DISKS : LTT : MEMORY : DISKS : LTT : MEMORY : DISKS
L&J rae TEES: ; pL a4 7525
SLIT : MEMORY : DISKS : LTT . MEMORY ; DISKS: LTT : MEMORY : DISKS : LTT : MEMORY : DISKS
SKS : LTT : MEMORY : DISKS : LTT : MEMORY : DISKS : LTT : MEMORY
@ Circle No. 123 @ Circle No. 124
TTT TTT TIT ier)
INNOVATIVE
TRS-80 SOFTWARE
Y Business Y Programming Aids
Y Personal Y Custom
Y Games Y Utilities
6 Years Microprocessor Experience!
BINDERS Orr 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. SAE for list alone, 85p
plus 30p postage for list and binder.
A.J.HARDING C(MOLIMERX)
28 COLLINGTON AVENUE,BEXHILL-ON-SEA,E.SUSSEX.
VISA
TEL: (0424) 220391
TTTITILIIITLIIIITiiifTiTfTiitlirtrliiiiliiiliriiitliiriitlirrl ii
@ Circle No. 125
18 PRACTICAL COMPUTING September 1979
Now, the complete MK 14 micro-computer
system from Science of Cambridge
VDU MODULE. £33.75
(£26.85 without character generator) inc. p & p.
Display up to 2K memory (16 lines x 32
chars. with character generator; or 4096
spot positions in graphics mode) on UHF
domestic TV. Eurocard-sized module includes
UHF modulator, runs on single 5 V supply.
Complete ascii upper-case character set can be
mixed with graphics.
CASSETTE INTERFACE MODULE.
£7.25, inc. p & p.
Store and retrieve programs on any cassette
recorder. Use for serial transmission down
single line atup to 1]Q baud (teletype speed
e.g. over telephone line, and to communicate
between two or more MK 14s.
POWER SUPPLY. £6.10 inc. p & p.
Delivers 8 V at 600 mA from 220/240 V mains -
sufficient to drive all modules shown here
simultaneously. Sealed plastic case, BS-approved.
PROM PROGRAMMER.
£11.85 inc. p & p.
Use to transfer your own program developed
and debugged on the MK 14 RAM to
PROM (748571) to replace SC10S
monitor for special applications, e.g.
model railway control. Software allows
MK 14 MICROCOMPUTER KIT ee eK
editing and verifying.
£46.55 inc. p&p.
Widely-reviewed microcomputer kit with
hexadecimal keyboard, display, 8 x 512-byte
PROM, 256-byte RAM, and optional
16-lines I/O plus further 128 bytes of RAM.
Supplied with free manual to cover To order, complete coupon and post to Science of Cambridge for DELIVERY WITHIN
operations ofall types = from games to 14 DAYS. Return as received within 14 days for full money refund if not completely satisfied.
basic maths to electronics design. Manual i
contains programs plus instructions for | To: Science of Cambridge Ltd, 6 Kings Parade, Cambridge, Cambs., CB2 1SN.
creating valuable personal programs. Also
a superb education and training aid - an Please send me:
ideal introduction to computer technology. OM«K /4standard kit @ £46.55. O Cassette interface module @ £7.25.
Designed for fast, easy assembly, supplied OExtraRAM @ £4.14 per pair. OPROM programmer @ £11.85.
with step-by-step instructions. DRAMI/O device @ £8.97 DOPower supply @ £6.10
| OVDU module including character Full technical details ofthe MK 14
generator @ £33.75. System, with order form.
S | | OVDU module without character All prices include p and p.
generator @ £26.85.
G b id | | I enclose cheque/MO/PO for > —~—SS————(total)
al 4 ge td | Name = _
6 Kings Parade, Cambridge, CAMBS., CB2 ISN. Address (please print — -
Tel: 0223 311488.
| Delivery within 14 days.
@ Circle No. !26
PRACTICAL COMPUTING § September 1979 19
GPW
electronics limited
(Computers)
GPW 201 8080A CPU with vector interrupt.
Price — Kit: £64. Assembled: £97.
GPW 302 Z80 CPU (2MHz) inc 2708 and power
jump.
Price — Kit: £87.60. Assembled: £120.
GPW 303 Z80 Upgrade kit to 4MHz.
Price — Kit: £12.
GPW 501 8K Static RAM 250ns.
Price — Kit: £116. Assembled: £144.
GPW 502 8K Static RAM 450ns.
Price — Kit: £97, Assembled: £126.
GPW 601 Tarbell Floppy Disc Controller.
Price — Kit: £123.40. Assembled: £158.
GPW 506 EPROM Board up to 16K of 2708
(not supplied)
Price — Kit: £45.
GPW 701 Serial/Parallel I/O including Kansas City
Tape Interface.
Price — Kit: £74. Assembled: £114.
GPW 801 Video Interface VB1B.
Price — Kit: £76. Assembled: £109.
GPW 850 Tape Interface with DMA.
Price — Kit: £71. Asembled: £104.
GPW 503 Memory Board 8K RAM and 8K ROM.
Price — Kit: £97. Assembled: £126.
GPW 901 Card Extenders.
Price — Kit: £19.70.
TANDY TRS-80 — 16K expansion kits complete
with headers/instructions. Price — £70.50
EXIDY SORCERER — CPU including 16K mem.
TV modulator output fitted. Price — £760.
CPU including 32K mem. TV modulator output
fitted. Price — £859.
S100 EXPANSION BOX. Price — £210.
MICROPOLIS S100 floppy disc (143K) and
controller. Price — £499.
MICROPOLIS S100 dual (630K) and controller.
Price — £1.200.
Larger range of $100 and other interface boards
available. Please write or telephone for a complete
list.
All items ex-stock at time of going to press; prices inclusive
of post and packing. Please add VAT. 24-hour order
service. Terms C.W.O. Access or Barclaycard.
|
tinburg
LINBURG ELECTRONICS LTD
QUALITY SEMICONDUCTORS WITH FULL
INDUSTRIAL SPECIFICATION
74LS TTL
74LS00
74LS01
74LS02
74LS03
74LS04
74LS08
74LS10
74L$14
74LS20
74LS27
74LS$30
74LS32
74LS42
74LS47
74LS74
74LS75
74LS90
74LS93
74LS155
74L$174
74LS367
MOTOROLA
MC6800P CPU
MC6810 RAM
MC6820 PIA
MC6850 ACIA
MC6875 CLOCK
D2 EVALUATION KIT
(MEK 6800 D2)
ZILOG
280 CPU 2.5MHZ
Z80 CTC
Z80 PIO
PROMS
2708 1K x 8EPROM
2716 2K x 8 EPROM
(TEXAS TRIPLE SUPPLY
VERSION)
SUPPORT CHIPS
MC1488 V24 Tx
MC1489 V24 Rx
8216 BUS DRIVER
AY-5-1013 UART
8 in. FLOPPY DISCS
(SINGLE DENSITY,
SINGLE SIDED)
£7.10
£3.20
£4.50
£4.50
£3.80
£176.00
19p
19p
19p
19p
20p
20p
20p
74p
22p
32p
26p
26p
88p
£1.00
30p
40p
54p
54p
57p
80p
54p
£14.00
£9.00
£9.00
£6.75
£17.00
PLEASE ADD 30p
POSTAGE AND PACKING
AND THEN ADD 8%
V.A.T.
LINBURG ELECTRONICS LTD
DEPT PC, MOSS WAY DONIBRISTLE
INDUSTRIAL ESTATE, HILLEND
DUNFERMLINE, SCOTLAND
TEL: (0383) 823222
@ Circle No. 128
APNMODONADEN DMO UU TODO CCOROROTOOROROORTROOPRODAD IO TDNNGUILODCGUGUGCCGUDOULONOUITUGUTUOUGUGNOUDLODIDGGE
Happy Memories
21L02 450ns 78p
4116 300ns £7.45
2114 250ns £5.40
2114 450ns £4.95
21L02 250ns 95p
2708 450ns £7.25
TRS-80 16K Memory Upgrade Kit: £70
$100 16K 250ns_ Static RAM Kit:
£195 With 4K £81, 8K £119
Low Profile Pins: 8 14 16 18 20 22 24 28 40
DIL Sockets Pence: 9 10 11 15 16 18 20 25 35
Our new shop is now open at the address below. We shall be
stocking a wide range of items to interest all those of you who are
building or plan to build your own microcomputer. Why not pay
us a visit? We are open from Mon to Sat 10 to 6 and often much
later
We stock a range of books covering fundamentals through to
advanced topics (like games)
We are NASCOM dealers for the South Coast.
Do-it-yourself with our range of wire wrapping aids and materials
from the O.K. corral, or Box-it-yourself with a Vero enclosure after
Soldering-it-yourself with Antex.
Our stocks are rapidly increasing; please write or call for latest
lists of available products. We welcome your suggestions for
stock lines. What do you find difficult to obtain? (We know about
buffers).
Please add 20p p&p to ail orders less than £10 in value. Cheques
or P.O.s payable to ‘Happy Memories’. Access or Barclaycard
at orders may be telephoned 24hrs a day. 10 ;
Prices quoted include VAT M
at 15% Please adjust for
any change in rate.
19 Bevois Valley Road, Southampton, Hants. SO2 OJP
Tel: (0703) 39267
MMU
@ Circle No. 129
PRACTICAL COMPUTING September 1979
146a London Road, Portsmouth, Hampshire gam
Tel: Portsmouth 693341. Telex: 86526 au
J
@ Circle No. 127
20
SHOW YO
EVERYTHING
Because we've got the
biggest and widest
range of micro-
computers, there’s
more for you to
bite on ata Byte
shop.
So you're
not only sure of
finding exactly
what you want: you
can take the opportunity to
experiment before you buy.
And because we're
backed by the huge financial
resources of a major
Branches at:
LONDON (WEST END):
48 Tottenham Court Road —
tel (01) 636 0647
PRACTICAL COMPUTING September 1979
investment group, we'll be
here tomorrow as we are
today. All over the UK.
So whether you
want a micro-computery
for yourhome, your
business, for industry Gimmes
a for education — or if
you'd just like to find out
which model you get on
best with — you'll find a
NOTTINGHAM: 92a Upper
Parliament Street —
tel (0602) 40576
visit to a Byte Shop a
Knew and invaluable
mesa x perience.
You can
call at a Byte
Shop any time
from Monday to
Saturday.
the
EUTE SHOP tid
The Byte Shop
426/428 Cranbrook Road,
Gants Hill, tlford, Essex
Telephone: (01) 554 2177
Telex 897311
MANCHESTER: 7-8 Corn
Exchange Building,
Fennel Street —
tel (061) 834 0220
@ Circle No. 130
2)
Yo PRICE SUMMER SOFTWARE SALE
Compusettes for Pets Speakeasy for Apple
Warlords
Games 1—Rhino, Hangman, Reaction Test £4 Microtrivia
Kids Stuff all at £7 per title
Games 2—Mastermind, Hammurabi, Go £4
Bulls & Bears
Games 3—Bridge, Bridge Dealer, 3-D, Transactional Analysis
Tic Tac Toe £4
Microchess 2.0 (for 8K Pet) £7 Financial Analysis
Mail Order only. Infogudies Ltd.,
142 Wardour Street, London.
@ Circle No. 131
COMMODORE BUSINESS SYSTEMS EXIDY PET ADD-ONS
PET 2001-4 Computer £460.00 Exidy Sorcerer 8K £650.00 MEMORY BOARDS
PET 2001-8 Computer £550.00 Exidy Sorcerer 16K £759.00 Expandamem 16K £295.00
PET 2001-16N Computer £675.00 Exidy Sorcerer 32K £859.00 Expandamem 24K £320.00
PET 2001-32N Computer £795.00 S 100 Interface £197.00 Expandamen 32K £392.00
PET 3022 Printer £645.00 Micropolis Dual Disk System £1200.00
PET 2040 Dual Floppy Disk £780.00 Video Display Unit £240.00 'NTERFACES
; ; IEEE — RS232 Unidirectional £85.00
25.00 110 E on Kit £99.00
PET Co IECE ot ee ead vara 1EEE — RS232 Bidirectional £185.00
C2N Cassette Deck £55.00 Aim 161 A/D Converter — 16 Way £130.00
KIM 1 Microcomputer £99.95 T.V.Interface £42.00
KIM 3B 8K Memory Expansion £129.95 DISK SYSTEM
KIM 4 Motherboard £69.95 Computhink Dual Drive £840.00
RS232 Printer Connector Cable £25.00
Dust Covers (4 colours) £8.00
Sound Box £12.00
All prices are exclusive of VAT unless - : : MISCELLANEOUS
otherwise indicated. All items are sold — C12 Blank Data Cassettes (per 10) £4.00
=a to the Company's Conditions of 5%" Diskettes (per 10)
Single sided/single density £30.00
i i:@ Double sided/double density £35.00
APPLE Continuous single part paper
8 x 12 (2,000 sheets) £15.00
APPLE Il 16K £950.00 9 x 11 (2,000 sheets) £16.00
APPLE Wt 32K £1050.00
APPLE II 48K £1150.00 Edge Connectors — 12 way £1.60
Disk Drive with Controller £425.00 24 way £2.55
Disk Drive without Controller £375.00 PRINTERS RS232 80 way £3.00
Parallel Printer Card £110.00 Micro Printer M879 £695.00
Communication Card £110.00 Teletype 43 Pin Feed £850.00 Mains Power Adaptor
High Speed Serial Card £110.00 Digital Decwriter LA34 £868.00 Input 240V 50HZ
Applesoft Rom Card £110.00 Digital Decwriter LA36 £840.00 Output 6V/7.5V/9V DC-300MA
Voice Card £165.00 Whymark 201 40 Column £395.00
Carry Case £25.00 Trend Com 100 £245.00 Co-Axial Lead Connector (2 metre)
16K Ram Add-on Memory £90.00 PET APPLE Interface £40.00 Aerial Splitter
Books and software packages now available.
22 Newland Street
HB COMPUTERS LTD sisi
Telephone (0536) 83922/
Computers tor Business Home 520910 Telex 341297
@ Circle No. 132
oF] PRACTICAL COMPUTING September 1979
Pic witht
The new EUROPLUS APPLE II is an enhanced APPLE II featuring: —
i) AUTO-START ROM — permits direct entry into application programmes from disc
at switch on. Also includes a reset protect function and improved screen editing.
i) PALSOFT ROM— Applesoft on a ROM saving RAM capacity and the need to buy
an Applesoft firmware card.
Ey NEW LOW PRICE! only £830 for the 16K version (B&W).
COMING IN SEPTEMBER: —
PASCAL card —This powerful new language on a card. Business users will find
PASCAL ensures faster and easier programming and permits simpler programme
modification. Autostart ROM on card. External 80 x 80 scrolling terminal
supported.
hr) New UK Colour Board —Giving much sharper colour definition.
PRICE LIST
16K (B&W Modulator) Europlus Apple fl —.-_._ «£830.00
Dise Drive withiGomtroner cee CAS. 00
VG Add 0in NAGI yal a rein £90.00
Hi-Speedisericl lirterfcac ee £11000
Peeireea lie) iyi ce ec ee CCCéE 110.00
Comms card __ . = 24 £14008
Aipplesott FirmrtWwerere@ anger £11000
Cenirenics Card See ee eee EO CED OU
Clock card , = £4000
ALL PRICES EXCLUDE VAT.
AVAILABLE EX STOCK FROM
Midwich Computer Company 9 Churgate Street, Old Harlow, Essex CM17 OJS Tel: (0279) 25756
@ Circle No. 133
PRACTICAL COMPUTING September 1979 23
Compfer Ltd.
Business Systems
We are the business software experts,
specialising in fully comprehensive disc
based software for the Commodore Pet
& Peripherals.
A working system is only ever as good as its
software and we consider that too much of
the business software hitherto available for
micros has proved to be the weak link.
Business users are entitled to expect the very
best from their systems and with this in mind
we have developed what we believe to be the
most sophisticated business software available.
If you are a business man wishing to acquire
a complete system that really does work for
you or a dealer who may be interested in
promoting our software, please complete
and return the coupon below or telephone
Don Steele who will be pleased to answer
your queries.
Compfer Ltd.
Preston Computer Centre
6 Victoria Buildings,
{| Fishergate, Preston.
Tel: O7'72- 57684
Se SS SS
: Please send me further information about your business
software and systems.
Name
Company
Address
Tel.No:
@ Circle No. 134
MICRO COMPUTER CENTRE,
314 Upper Richmond Road West,
East Sheen, S.W.14 876 6609.
Business Specialists/Authorised Dealers for
PET
Computers
Standard PET with integral cassette and
calculator type keyboard. 8K bytes of memory
PET with 16K bytes of memory and large
keyboard. External cassette optional £695.00
PET with 32K bytes of memory and large keyboard.
External cassette optional £795.00
Printers
Whymark 201 — 20 columns complete with interface ¢400.00
Datac BD80 — 80 columns £750.00
1-way Interface £106.00
Teletype 43 — 132 columns — Upper and
Lower Case Keyboard
2-way Interface
Memories
16K Memory Extension for 2001 — 8K
24K Memory Extension for 2001 — 8K
Disc Drives
Compu/Think Twin Floppy Disc Drive — double
sided discs — 100K per side £833.00
Pet Twin Floppy Disc Dual Drive including cable £815.00
Cassette Recorder £55.00
The above prices are exclusive of VAT. All the above
items are IN STOCK at time of going to press.
We stock all PET accessories and handbooks PETSOFT
and PETACT Programs.
£550.00
£900.00
£186.00
£276.00
£337.00
@ Circle No. 135
OUR 1979 CATALOGUE RAM
including the first edition of 2102A-2
10
STOP PRESS aac"
* LATEST LOW PRICES 16 For £16.96
* FASCINATING NEW ITEMS
* SPECIAL OFFERS
a bargain on their own
* LOWEST PRICES EVER FOR TTL
* FREE 45p WORTH OF VOUCHERS
USE. OUR ““ORDER-RING” LINES
VAT INCLUSIVE PRICES P + P 25p
CHROMASONIC
electronics
56 Fortis Green Road,
Muswell Hill London N10 3HN
Telephone 01-883 3705/2289
Has with Woes
@ Circle No. 136
PRACTICAL COMPUTING September 1979
WHY BUY A
MICRO-COMPUTER FROM
PHTALECD seavicine cro.
BECAUSE
1) Established company trading since 1971 7) We can arfange finance
8) We offer, after the three-month warranty, a
service contract from £69-50
9) You benefit from our experience of having
2) -Electronic servicing is our speciality
3) We have in house programmers/systems
analysts
4) Weh =. Sold over 150 micro-computers to industrial,
e Remegeee OMOH SETV ICSE Nileees educational and business, personal users.
5) We will demonstrate the PET at your 10) We specialise in programs and interfaces for
anaes weighing applications for average weight
6) We can customise the PET to,your control and counting etc.
requirements
8K £550:00 — VAT. Ail 'PETS’ sold with a Basic Tutorial Tape
16K £675:00 — VAT.
32K £795:00 — VAT.
In our showroom we sell
New Large
Books, Programs etc.
Keyboard ‘PETs’
Now in Stock
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 Tél. WaKne 20727/23637
@ Circle No. 137
PRACTICAL COMPUTING September 1979 25
AI. NewBear Systems
INTRODUCING
APPLE IT.16k
£830.00
COMMUNICATIONS INTERFACE CARD
£110.00
HIGH SPEED SERIAL INTERFACE CARD
£110.00
PROTOTYPING CARD
£18.00
CARRYING CASE
£25.00
NORTH STAR
HORIZON
S100 bus Z80 based micro.
16K RAM WITH SINGLE DISC DRIVE
(Double Density)
£1265
32K RAM WITH DOUBLE DISC DRIVE
(Double Density)
WITH 2 SERIAL AND 2 PARALLEL PORTS
£1983
PARALLEL PRINTER INTERFACE CARD
£110.00
Please Telephone for
a Demonstration .
All prices subject to 15% VAT.
Head Office:
40 Bartholomew Street, Newbury, Berkshire
Telephone: 0635 30505 Telex: 848507 NCS
Northern Office:
2A Gatley Road, Cheadle, Cheshire
Telephone: 061 491 2290
@ Circle No. 138
FEATURES INCLUDE:
*20 COLUMN PRINTER
* 20 CHARACTER
ALPHANUMERIC DISPLAY.
* FULL 54 KEY TERMINAL-STYLE
KEYBOARD _
* TTY INTERFACE
* TWIN CASSETTE INTERFACE
* RAM — 1K TO 4K OPTIONS
OPTIONAL EXTRAS INCLUDE:
8K‘BASIC’ INTERPRETER RQM
aay — £70.00
4k ASSEMBLER ROM — £59.50
POWER SUPPLY -— £41.83
CASE (Including Power Supply)
ee — £78.00
EXPANSION MOTHERCARD
— £136.50
Pelco (Electronics) Ltd
Enterprise House 83/85 Western Road HOVE East Sussex BN3 1 JB
Tel: Brighton (0273) 722155
Buy it with your Access or Barclaycard.
26
£249-50
+ VAT
AIM 65 comes to you fully built
and tested with a full alphanumeric
keyboard, 20 character display
and a 20 column printer - é
for keeping a permanent /
record of all your work. Available
in 1K- and 4K-byte RAM versions,
AIM 65 is designed around the
6502 CPU, which has 64K address capability
with 13 addressing modes. This is the
microprocessor at the heart of many other,
more costly, systems such as PET and
APPLE.
AIM 65 has a 4K ROM-resident monitor
program for all peripheral control and user
programming functions, Spare sockets are
included for expanding on-board program
memory via user PROM-based programs
and/or Rockwell assembler, text editor and
BASIC interpreter plug-in options.
AtM 65 has a connector for external
access to system bus for memory and
VO expansion, a separate connector for
interfacing a teletype and two cassette
recorders. There is a user-dedicated
Versatile Interface Adaptor, featuring three
8-bit, bidirectional ports (two paraliel, one
serial) and two 16-bit interval timer/event
counters — thus allowing the user to
interface his own system, without extra
interface devices in many cases.
AIM 65 is probably the most effective.
low-cost microcomputer development
system available — an invaluable
educational aid to first time users and an
ideal general purpose micro-computer for
the engineer.
AIM 65 is available in the UK from
PELCO ELECTRONICS LTD at £249.50 +
VAT, complete with User's Manual and
Schematic, R6500 Programming and
Hardware Manuals and a handy pocket
reference card. i
@ Circle No. 139
PRACTICAL COMPUTING September 1979
Buy a System...Not just a ‘‘ Pretty Box’”’
The SD System*—From about 97p per hour (40-hour week)
*The SD System includes:
SDS-200 Microcomputer T.I. 810 Printer (or equivalent)
i.e, NEC SPIN WRITER £1,899. SDS 200 £4,750, T18 10
£1,499
The SDS-200 TOTAL System features:
System Hardware
The SDS-200 gives you features that are not
found in systems costing thousands more.
State-of-the-Art Engineering. Quality Production
and Full Reliability testing make the SDS-200 a
dependable, compact and easy to operate data
processing system.
e Up to 256K Bytes RAM
e Full Keyboard with Special Accounting Key Pad
e Large 12in. Video Display Screen
e Full Cursor Control including Addressable Cursor
e Blinking, Underlining, Reverse and Protected Fields
e Uses 8in. Flexible Diskettes for Permanent Storage 2
Mbyte on-line
e Forward and Reverse Scrolling
e Capable of up to 160 Special Characters
e Expandable with Memory and Peripheral Equipment
~ e Will Operate as a Remote Batch Processor for Large Systems
eS 100 industry standard bus
e 4 spare $100 slots.
System Software
A range of Business Programs are available from
CAP-CPP written in Microcobal.
The system will support all normal high level languages
including:—
Fortran
Cobol
Basic
CP/M
Authorised dealers are:
Anglo American Computers Ltd
Milburn House, Suite D, Dean Street
Newcastle-upon-Tyne.
Tel: 0632 29593
Apple Computers
Anfield, Glenalmond
Perthshire 073-888 267
A Total System
SD Systems knows that small
businesses do not keep full-time
programmers on staff. We also know
that individually designed business
programs can be expensive on a
one-time basis. That is why we offer
the SDS-200 and compatible
business software.
Leasing Available
The SDS-200 is available by leasing.
This gives the small business the
opportunity to select the method of
acquisition that best fits their needs.
SVSnEMsS
SDS-200 Expandable
The SDS-200 is designed in a
manner to give you expansion
capabilities. As your needs change
the computer system that you select
today should be able to change with
you. By the addition of memory and
peripheral equipment, the SDS-200
can expand to fit your needs.
Bell Computing Ltd
1 Froghall Lane, Warrington
Tel: 0522 411271 (33137)
Codified Computer Systems Ltd,
69 Calabria Road,
London N5 1HX
Tel: 01-226 1319.
UK Distributor:
AIRAMCO LTD
(0294) 57755
Unit A2, 9 Longford Avenue, Kilwinning Ind. Est.,
Kilwinning, Ayrshire KA13 6EX.
Dealér enquiries invited
Telex 779808
a ——
PRACTICAL COMPUTING September 1979
|
@ Circle No. 140
27
NL.
Please contact NEWBEAR for a complete catalogue of books.
NEWBEAR, 40 Bartholomew Street, Newbury, Berkshire RG14 5LL
Introduction to Microcomputing
Volume 0. The Beginners Book
Volume I. Basic Concepts
Volume II. Some Real Products
Volume III. Some Real Support
Devices
Understanding Microcomputer
and Small Computer Systems
Introduction to Computers
Introduction to Computers in
Business
An Introduction to Personal
and Business Computing es
etting Acquainted with Micros £
Home Computers — A Beginner’s
Glossary and Guide £
Getting Involved with your Own
Computer — A Guide for
Beginners
Introduction to Computer
Programming
The First Book of
Microcomputers
A Consumers Guide to Personal
Computing and
Microcompuiers
£ 5.95
oy 5:95
£18.95
£11.95
£ 7.56
£11.15
£10.45
5.75
7.95
4.95
4.75
3.84
3.60
5.65
Basic Books
Introduction to Basic
Beginning Basic
Introduction to Basic
Some Common Basic Programmes
Payroll with Cost Accounting in
Basic
6.50
2.95
1,95
£ 6.45
9.95
ALMARC PRESENTS:
Instant Freeze and Dried
Programming in Basic
lustrated Basic ©
Beginning Basic
Learning Basic Fast
Advanced Basic
Microcomputer Basic
The Basic Workbook
Discovering Basic (a problem
solving approach)
The Users Guide to North Star
Basic
Basic with Business Applications
Basic and the Personal Computer
A Guided Tour of Computer
Programming in Basic
Basic Basic (An introduction to
Computer Programming in
Basic Language)
Advanced Basic Applications
and Problems
6800 Books
6800 Programming for Logic Design
6800 Assembly Language
Programming
Using the 6800 Microprocessor
77-68 6800 Microprocessor
6800 Software Gourmet Guide
Cook Book
MORE FROM VECTOR GRAPHIC
Now Vector Graphic give you more for your money with
the 48K dynamic ram board and the System B
THE VECTOR GRAPHIC MZ
NewBear Books
Telephone: Newbury (0635) 30505
Practical Microcomputer
p Programming (6800)
-25 The 6800 Microprocessor
-95 D.N. 4 Definite description of the
6800 Instruction Set
‘ 60 Z80 Books
4.50 Z80 Programming for Logic Design
*““ Z80 Technical Manual
4.90 Z80 P10 Technical Manual
““" Z80 Programming Manual
Z80 Microcomputer Handbook
£10.00 2 :
Practical Microcomputer
fan eels Pr ; 780
£10.36 Programming (260)
Pascal
£ 4.16 Pascal: User Manual & Report
Problem Solving Using Pascal
Programming in Pascal
£ 5.40 A Practical Introduction to Pascal
6502
ee The Best of Micro 6502 Journal
Sym Reference Manual
£ 5.95 Sym Programming Manual
First Book of Kim
£ 6.95 6500 Hardware Manual
£ 5.65 6500 Programming Manual
£ 7.50 Programming the 6502 SYBEX
Fortran
(oe Elementary Computer
Programming in Fortran IV
te MmMhhhhthth
£17.56
3.60
1.50
NNNNNNG
WOANdanwe
6.30
Fortran with SF/R and WATFEV-S £ 6.95
@ Circle No. 141
THE VECTOR GRAPHIC SYST
*“ AMHZ Z80A CPU
* 48K ram
* 630K Bytes disk storage
* Serial port and two parallel ports
* Prom/ram Board with monitor
* MDOS Operating system
* Z80 Assembler
* Basic Interpreter
Price £2300-00 plus VAT
* Complete Vector MZ system plus:-
* Vector Mindless terminal
* Flashwriter 2 video board (24 x 80)
* Software driver on prom
* MZOS North Star compatible DOS
* CP/M configured by Almarc
Price £2850-00 plus VAT
Plus a large range of CP/M compatible software including Fortran, Cobol, Macro
assemblers etc.
Contact: ALMARC DATA SYSTEMS LTD.
29 Chesterfield Drive, Burton Joyce, Nottingham.
Telephone 0602 248565
@ Circle No. 142
28 PRACTICAL COMPUTING September 1979
TRAINDSA
EXPANSION MOTHERBOARD
SINGLE BOARD
PERSONAL
TRITON 235
THREE NEW EXCITING EXPANDABLE SYSTEMS ~
DESIGNED FOR EASE OF CONSTRUCTION
AND FLEXIBILITY. KITS COME Vd
COMPLETE WITH CASE, POWER
SUPPLY, FULL KEYBOARD, PCB. jp itantPen
ALL COMPONENTS AVAILABLE SEPARATELY
SEE CATALOGUE.
FULL HARDWARE AND PROGRAMMING MANUAL AVAILABLE.
THE SYSTEM I EASY TO EXPAND AND IS WELL SUPPORTED.
FEATURES 2. 2.5 OR 7K BASIC IN EPROM (SEE CATALOGUE).
@SINGLE BOARD @ THREE FIRMWARE OPTIONS
@HOLDS UP TO 8K MEMORY —@ BASIC IN EPROM
@ VHF OR VIDEO OUTPUT @64 GRAPHICS CHARACTERS
@ CASSETTE INTERFACE @ PLUS IN EXPANSION BOARDS
Personal Computer £286 +var
TRITON. Expand your Triton simply ‘086
COMPUTER
PRODUCTS
Ce,
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 CONNECTORS
8K RAM
CARD <S
TRITON 8K STATIC
RAM CARD KIT USES
2114 LOW-POWER 4V
STATIC RAMS. ON-BO
REGULATION. NEW
JUMP SELECT a
PCB ONLY £5, RAMS £5.50 VAT
KIT LESS RAMS €31 INCL 5KTS COMPONENTS
8K EPROM
CARD
TRITON 8K EPROM CARD /
KIT DESIGNED TO TAKE UP TO /
8 x2708 EPROMS (1K x8)
AS RAM CARD
PC8 ONLY £15
KIT LESS EPROMS £31
EPROMS (BLANK) £9
PLUS VAT
i
COMPLETE KIT VAT
BI-DIRECTIONAL
MATRIX PRINTER rier L
THE BD80 IS A LOW-COST, 80-COLUMN LINE PRINTER
WITH MICROPROCESSOR CONTROL TO PROVIDE
EXCELLENT AVAILABILITY AND PERFORMANCE.
@5 x7 Dot Matrix @Full ASCil Char. Set @ Self Test
@10 Char. per inch @10 Lines/sec Paper Advance
@6 Lines/inch @112 Char./sec @Fully Cased
@400 Char. Buffer | @82 Lines per minute
VIDEO MONITOR
NEW
A BRAND NEW FULLY-CASED (METAL)
HIGH-RESOLUTION 10in VIDEO MONITOR
WITH PSU FOR ONLY £69+ VAT.
IDEAL FOR TRITON OR ANY HOME
COMPUTER SYSTEM. CARRIAGE BY
SECURICOR CAN BE ARRANGED. SEND
SAE FOR DETAILS OR SEE OUR NEW CATALOGUE
A
UNIQUE
PRINTER
PCB CONNECTORS
FAST EDGE CONNECTORS GOLD CONTACT
AND DOUBLE- SIDED PCB CONNECTORS
RELIABLE Jin. PRICE .156in. PRICE
22/44 L 6/12
25/50 10/20
28/56 15/30
30/60 18/36
35/70 22/44.
36/72 28/56
40/80 36/67
43/86 43/82
VIDEO DISPLAY
INTERFACE MODULE
Completely built and tested
the SFKE X 68364 card uses the
industry standard SFF 96344 CRT
control chip and allows ASCII
Parallel input of data to
be output to Video monitor
64 character by 16 line
display full cursor control.
Single 5V supply. Full details
available on request (send SAE) w.
VHF modulator available £2.50 extra + VAT
£69
+VAT
Gr»
oy
SWITCH-SELECTABLE 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,
RELIABLE HARD COPY. WE CAN SUPPLY
CONSUMABLES.
mer Een
= SPRRAAR PERRO
£4.60
BUS) +VAT °
LM747CH . 7912K 80 18M
LM748CN-8 0. aaa a 48M
LM748CH 2 3 cmos
(M1458H DIL SKTS cb4011
LM1458N-8 C4040
M1488) + full range
LM14890
(M1489AD
LM4495N-14
LM3302N
LM3401N
LM3403N
LM3900N
TLOSOCP
TLOBICP
TLos2cP
TLOB3CN
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LM741CN-14
LM741CN-8
LM747CN-14
HOME COMPUTING CATALOGUE
If you're in town, visit our showroom in
Chapel Street, next to Edgware Road tube
station. We have Tritons on display plus a
comprehensive range of components and
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TRITON DOCUMENTATION
available separatety as follows, prices include p&p
Triton manual — detailed circult description and constructional
details + user documentation on level 4.1 monitor & basic
L4.1 listing — listing of 1K monitor & 2K tiny basic
L5.1 user documentation on level 5.1 firmware
£5.70
£4.20
£1.20
5AM NEW
TANS || M4 SIZE CATALOGUE
i FILLED WITH OUR
1\\
L5.1 listing — listing of 1.5K monitor & 2.5K basic £5.20 : og me Wee \ LATEST PRODUCTS
L6.1 user documentation on 7K basic interpreter £1.70 accessories, specifically for personal com vm \\ 40p+ SAE
Motherboard, 8K RAM & 8K EPROM constructional details SAE puter users. Books, mags, tapes, data,
User group newsletter subscription £4 per annum cables plus much more. Showroom open 6 ALL PRICES
EXCLUOE VAT
TRANSAM COMPONENTS LTD.
12 CHAPEL STREET, LONDON, NW1
TEL: 402 8137
@ Circle No. 143
Triton software — Send SAE for list of programs available for Triton.
TRANSAM
days a week. (Half day Thurs from 1.30 pm)
ALL PRICES
V AT EXCLUDE VAT
PRACTICAL COMPUTING September 1979 29
30
Which British system can offer the following:
“ COLOUR. Aerial Input, Alphanumerics
and Graphics
BBC Television Teletext
service
IBA Television Teletext
service
ROM-Resident
Interpreter
Motorola 6800 Machine
Code
Instant Information service
* CEEFAX.
ORACLE.
BASIC.
MONITOR.
VIEWDATA.
TECS:
TECHNALOGICS
EXPANDABLE
COMPUTER SYSTEM.
Prices start at around
£360.
Rack-mounting and Tabletop versions
(illustrated) —The Logical Development everyone
has been waiting for.
Please send large S.A.E. for details to:
TECHNALOGICS (DEPT. PC)
8 Egerton Street, Liverpool L8 7LY
@ Circle No. 144
VERO ELECTRONICS LTD RETAIL DEPT.
Industrial Estate, Chandler’s Ford,
Hampshire SO5 3ZR
Tel: (04215) 2956
BUILD THE
NASCO M y # British Design Ww UK Best Selling Kits
COMPUTER Futt arter SALES SERVICE & GUARANTEE
We are the Sole Approved London Stockist and Netional Distributor
FREE MODULATOR and B-BUG
FEATURES 2
te Supplied in kit form for r \
12,000 ALREADY SOLD a
KITS 1N STOCKS
————
£165 8° VAT
POST FREE
self-assembly
% Full documentation supplied
Ww Fully screened double-sided
plated through hole printed circuit —_
ley
board
Ww Full 48 key keyboard included
4 2K x 8 Ram re
Ww 1K x 8 monitor program in
Eprim
we Powerful Mostek Z80 CPU
Ww 16 x 48 Character display
interface to std un-modlitied T.V.
% T.V. display memory mapped
for high speed access
tr On board expansion to 2K
< 8 Eprom
%& On board expansion tor
additional 16 1/0 lines
%& Memory may be expanded to
full GOK
EXPANSION
tw Expansion buffer board £32.50
SOFTWARE
w& 1K x 8 monitor program
MEMORY KITS (inclusive all providing
hardware)
8K .. £85
16K ae . £140
32K . £200
w 1/0 board with decoders and
all hardware except ICS will
accept up to 3 PlOs, 1 CTV and
1 UART. f £35
OTHER HAROWARE
Ww 3A power supply for up to
32K expansion £19.90
Ww 8 cnerating commands.
supporting Mem examine/modify.
tabulate. copy. break, single step
execute tape. load. tape dump
a Reflective monitor addressing
for flexible monitor expansion
through user programs
% Monitor sub-routines include—
delay ASCII coding. binary to hex
conversipn, cle screen. scroll up,
String print, cursor shift and many
others
te 3A power supply for up to
32K expansion Mk It £24.50 NEW T-4 operating system in (2)
we 8A power supply for targer 2708 EPROMS upwards
than 32K expansion £60.00 compatible from T2 and 8-BUG
aw Expansion card trame . . £29.50 .. £26.00
we —E PROM programmer. £40.00 Tiny Basic . £26.00
Ww E PROM Eraser £25.00 Super Tiny Basic (with editor
Ww Keyboard cabinet . £3.50
and machine utility routined) £35.00
we Programming manual £4.00
Zeap assembler editor . £32.00
ke VAT 8% ALL ITEMS EXCEPT BOOKS ye DEMONSTRATIONS CON.
TINUOUS DAILY ke WE WELCOME EXPORT—EDUCATIONAL AND
INDUSTRIAL ENQUIRIES ye FREE BROCHUME—SEND SAE 94 x 64
STAMP 12¢p.
D i @ All mail to ;
PLS Henry's Radio = =)
ENRYS oanereaelrd Ee)
Phone (01) 7231008 —- London W2
@ Circle No. 145
The Vero S100 Sub Rack is a 19” rack
mountable development kit, complete
with its own power supply and backplane
motherboard, for the construction and
evaluation of microprocessor based
systems to the S100 format. The power
supply provides three voltage levels —
+ 8V, + 18V and -18V. The Sub Rack
has its own cooling fan providing airflow
across the boards and the power supply.
A full range of allied items to enable a
complete system to be constructed are
available.
ORDER CODE | ITEM DESCRIPTION
$100 Sub Rack
$100 Dip Board
$100 High Density Board
$100 Square Pad Board
Compatible Connector
(Solderlug)
Compatible Connector
(Miniwrap)
$100 Extender Board
Mk. II D Series Case
Keyboard Console
Verowire Wiring Kit
188-2341H
06-0095L
06-2337L
06-2338F
15-1630K
15-1632L
09-2340H
48-8345K
75-2867G
79-1729L
@ Circle No. 146
PRACTICAL COMPUTING September 1979
NEW DOLPHIN BD 80 PRINTER
Low cost 80 column printer combining simple mechani-
cal design with sophisticated micro-processor control,
upper and lower case, 112 c.p.m., many features.
Stand, cables, memory buffers available.
E-stock prices from £595.
| Dealer enquiries invited.
SPECIAL OFFERS for August only — holiday reading.
Intro to personal and business computing £4.80.
The mind appliance home computer applications £4.00.
Micros from chips to systems £6.80.
110 cosmos Digital I.C. projects for the home constructor £2.65.
Illustrating Basic £2.10.
Programming the 6502 £7.25.
The microprocessor and its application £12.25.
8080 galaxy game £5.50.
How to build a computer controlled robot £4.75.
'NEW PRODUCTS
DOLPHIN PRINTER is plug compatible to the Sorcerer's
serial and parallel interfaces and is supplied in a beige
cabinet — plug in and print.
The EXIDY MONITOR and PROGRAM DEVELOPMENT
ROM PACS are on demonstration in our showroom.
SORCERER TECHNICAL Manuals and handbooks are
available ex-stock.
| A vast amount of software is nearing completion, so
please keep in touch for early news of availability.
EXIDY SORCERER — A COMPLETE BUSINESS SYSTEM
UNDER £3000 + VAT 32K Machine with Z80 processor
and 8K ROM BASIC. 128 character ASC11 keyboard and
superb graphics.
DOUBLE DRIVE configured MICROPOLIS DISK SYSTEM
with MDOS or CP/M 630Kb. Professional quality
monitor, various sizes up to 16”. Printer — optional 80 or
| 132 column printer. Software packages are available or
can be written to your own specification.
The system can be expanded to suit your own
applications.
UNDER £1000 — BASIC SYSTEM
32K Machine, 10” professional monitor (not a converted
TV), quality cassette recorder, necessary cables, manu-
| als etc.
Price £999 + VAT.
Sorcerer Prices from £650 (8K).
77/68 BEARBAGS - The well-supported 6800 based ‘.
from Newbear. Active user group.
PRINTERS — CENTRONICS, DOLPHIN, OK11.
MONITORS — Professional quality 9”,
{ideal for teaching).
10", 12”,. 16"
COMPUTER BOOKS — for professionals, hobbyists,
businessmen and newcomers. Catalogue now contain-
ing updates — over 500 titles — Micro, Mini and
Mainframe. Quantity discounts available.
CROMEMCO Z2 - The powerful one — ASSEMBLER,
MACRO ASSEMBLER, FORTRAN, COBOL, DATA BASE
MANAGEMENT, WORD PROCESSOR.
Prices from £395 (Z80 Single Board Computer)
NORTH STAR HORIZON - The popular computer for the
business user. Expandable to 48K, 3 diskettes and |
hardware floating point. Basic system 16K. RAM, serial
interface. EXTENDED BASIC, DOS, CP/M, mini diskette
and power supply.
Prices from £1295.
SOL 20 - The professional terminal computer re-
nowned for its high quality capacitative keyboard and
Word Processing application. Minimum 16K RAM,
monitor, serial and parallel interfaces. EXTENDED
BASIC, FORTRAN, FOCAL, ASSEMBLER, EDITOR,
GAMES, mini floppy disks.
Prices from £1785.
SOL* STAR WORD PROCESSOR from £2500.
THE COMPLETE SERVICE
Feasibility studies — undertaken by our senior consul-
tant analysts with long experience of commercial data
processing.
Software packages available and/or specially designed
and written for your own applications.
We can supply work stations for your computer
hardware, standard configurations or made to mea-
sure. Insurance, maintenance, HP facilities BARCLAY-
CARD, TRUST-CARD, ACCESS.
Universities, Colleges and Schools — official orders
welcome.
OFFICES & SHOWROOM open Monday-Saturday 10.00a.m.-6.00p.m.
Personal callers welcome (Please phone first).
IL
34B London Rd., Blackwater, Camberley, Surrey. Telephone (0276) 34044.
Telex 858893
PRACTICAL. COMPUTING September 1979
@ Circle No. 147
3!
8K XTAL BASIC
FOR NASCOM |!
. Commands:— CALL CLEAR CLOAD CONT CSAVE READ
..DATA..RESTORE DEF..FN DIM EDIT END FOR..TO..STEP..NEXT
GOSUB..RETURN GOTO IF..THEN INPUT LIST NAS NEW
ON..GOTO ON..GOSUB OUT POKE PRINT REM RUN SPEED
STOP WAIT SPC() TAB() POP PRINT
. Variables:— Names must start with a letter, but can be up to any
length. First two characters used to distinguish one variable from
another. Strings of up to 255 characters, also Multi-Dim, Arrays
and String Arrays. Numbers range. from +/- 1E+/-—38, with an
accuracy of six significant figures.
. Functions:- ABS ASC ATN CHR$ COS EXP INP INT LEFTS LEN
LOG MID$ PEEK POS RND RIGHTS SGN SIN SIZE SIZES SQR
STR$ TAN VAL.
. Operators:— Arithmetic:
Relational:
+ — */** (“To the Power of’’)
See es
Arith-Logical: And Or Not
String: + {(Concatenation)
. Cassette commands:— CSAVE CLOAD for saving and loading
WHY BUY AN IMITATION GREY WHEN
THE REAL CREAM IS AN
APPLE
THE SW AGENTS
£920
£ 90 fitting & testing £10 extra
£830
APPLE |i 16K (colour
a16K MEMORY INCREM
APPLE II 16K (B&W)
ALL APPLE ADD-ONS NORMALLY IN STOCK
APPLE SOFTWARE; MANY GAMES FROM £5-£15.00
STOCK CONTROL £100
NEW WORD PROCESSOR £140, including lower-case
‘LETTER WRITER adaptor package
ALL PRICES EXCLUDE VAT & CARRIAGE
DURANGO
THE FIRST FULLY-INTEGRATED DESK-TOP SYSTEM
DUAL QUAD-DENSITY MINI-FLOPPY DISCS FOR 1.9M BYTES ON LINE
9x9 DOT-MATRIX BIDIRECTIONAL PRINTER, 165cps, VARIABLE WIDTH.
48K/64K RAM, WITH 8085 cou.
FULL KEYBOARD WITH 10-KEY NUMERIC PAD
VDU WITH 24x80 or 16 x64 CHARACTERS
POWERFUL DISC BASIC (14-DIGIT ACCURACY).
MULTI-TASKING TO 4 USERS PLUS OPTIONAL 20 M-BYTE FIXED
APPLICATION SOFTWARE — SMALL BUSINESS, A/C PAYABLE/RECEIVABLE,
GENERAL LEOGER, ORDER ENTRY/INVENTORY CONTROL INVOICE/SALES
ANALYSIS, PAYROLL, ETC. PRICES FROM £7,500
TEXAS TI-PROGRAMMER. A MUST FOR MACHINE LANGUAGE BUFFS,
HEX-OCTAL-DECIMAL CONVERSION, ARITHMETICS OPS. IN THREE BASES,
SHIFT LEFT/RIGHT, IS COMPLEMENT, OR, AND, XOR, ETC. £46-25
TEXAS TI99/4 40 MAGDALENE ROAD
HOME COMPUTER TORQUAY
PHONE DEVON
FOR DETAILS ENGLAND
Tel: 0803 22699
NASCOM NATIONAL DISTRIBUTOR TRADE INO WELCOME.
programs. Also CSAVE@ CLOAD@ for saving and loading of
numerical arrays.
. Special Commands: EDIT — Powerful line editor. CALL — Machine-
code subroutine call. NAS — Return to ‘NASBUG’ under software
control. OUT, INP & WAIT — for control of I/O ports.
. Compatibility:— Tape routine provided for use with T2 Monitor.
Fully compatible with T2, T4 & B-Bug Monitors.
. Size:— Actually fits in 7K of Ram (1000H-2BFFH),But recommend
>=16K Expansion Ram in your system.
. Availability:— On C12 cassette tape, with documentation, NOW.
. Price £35.00 + VAT.
MINIMUM SYSTEM GAMES TAPE £6+ VAT
TINY BASIC GAMES TAPE £12+ VAT
NEW WORD PROCESSOR FOR XTAL BASIC £70+ VAT
SHOP OPEN
0930-1730
EXCEPT
WED & SUN
Closed for lunch
1200-1300 hrs
| me ‘C.
{ a
INTRODUCING THE HAZELTINE 1400 SERIES OF ECONOMY
VIDEO TERMINALS TO MICROCOMPUTER USERS
Hazeltine Ltd., the U.K. subsidiary of Hazeltine Corporation, a world
leader in Information Electronics for more than half a century, announces
the introduction of a low-cost series of interactive video terminals, the
1400 series, aimed specifically at the practical microcomputer market.
The Hazeltine 1400 Terminal, priced at £550 one-off to end-users,
contains all the major features required of an interactive video terminal,
including all 128 ASCil codes, 64 displayable characters, cursor
addressing and sensing, variable transmission rates up to 9,600 baud,
E1A standard RS232C interface and remote command facility.
The Hazeltine 1410 Terminal has all the features of the 1400, and in
addition has a separate integral numeric pad provided to facilitate
efficient numeric data entry. This terminal is believed to offer more of
what users want than any other TTY-compatible terminal currently on
the market. itis available for around £600 one-off to end-users inthe U.K.
Hazeltine, has achieved this price/performance by utilising advanced
microprocessor design, and produced terminals with an ultra-low com-
ponent count. The company manufactures all the sub-assemblies
including monitor, power supply and controller. Reliability and quality
are significantly enhanced since all the electronics are contained onone
pcb, eliminating all inter-connections other than input power and
monitor connections.
Both terminals are normally available ex-stock from Hazeltine or its
distributors throughout the United Kingdom and are supported under
one of Hazeltine’s Comprehensive Maintenance policies.
Hazeltine Ltd, Terminal House,
14 Petersham Rd, Richmond, Surrey TW25BR
Tel: 01-948-3111 Telex:928572
DISTRIBUTORS
Billing Machines Ltd., Unit 22, Galowhill Road, Brackmills Estate, Northampton Tel: Northampton 66416 Telex: 31504
Fortronic (Fife) Ltd., Donibristle Industrial Estate, Dumfermline, Fife KY11 5JW Tel: Dalgety Bay 823121 Telex 727438
Rair Terminals, 32 Neal Street, London WC2H 9PS_ Tel: 01-836 4663 Telex: 298452
Specialist Office Supplies, 269/271 Barlow Moor Rd., Chorlton-cum-Hardy, Manchester Tel 061-8610757 Telex: 6671 51
Technico (Communications) Ltd., Astral House, Adelaide Rd., Dublin 2, Ireland Tel: Dublin 688222 Telex 5129
Gamma Computer Products Ltd., Gable House, Turnham Green, London W4_ Tel: 01-995-3721
Hamilton Rentals, (centralised enquiries through) 53 Curtain Rd., London EC2 Tel: 01-739-3444 Telex: 263121
COMPUTERS
AND
OMPON
NTS
ei
@ Circle No. 148
32: PRACTICAL COMPUTING September 1979
THE EXPANDABLE GENERAL-PURPOSE MICROCOMPUTER
DAMPING FACTOR-> 4£-04
>
>>>> THE 3e02 aLam MAB GRAPHICS P??
Pg Can use thee toe staviatiens’”
s
Py taTaccrn
MACHINES SUZ
THE RESEARCH MACHINES 3802
A UNIQUE TOOL FOR RESEARCH AND EDUCATION
Microcomputers are extremely good value. The outright purchase
price of a 380Z installation with dual mini floppy disk drives, digital
1/O and a real-time clock, is about the same as the annual mainten-
ance cost of a typical laboratory minicomputer. It is worth thinking
about!
The RESEARCH MACHINES 380Z is an excellent microcomputer for
on-line data logging and control, In university departments in
general, it is also a very attractive alternative to a central main-
frame. Having your own 380Z means an end to fighting the central
operating system, immediate feedback of program bugs, no more
queueing and a virtually unlimited computing budget. You can
program in interactive BASIC or run very large programs using
our unique Text Editor with a 380Z FORTRAN Compiler. If you
already have a minicomputer, you can use your 380Z with a floppy
disk system for data capture.
What about Schools and Colleges? You can purchase a 380Z for your
Computer Science or Computer Studies department at about the
same cost as a terminal. A 380Z has a performance equal to many
minicomputers and is ideal for teaching BASIC and Cesil. For A
Level machine language instruction, the 380Z has the best software
front panel of any computer. This enables a teacher to single-step
through programs and observe the effects on registers and memory,
using a single keystroke.
WHAT OTHER FEATURES SET THE 380Z APART?
The 380Z with its professional keyboard is robust, hardwearing
equipment that will endure continual handling for years. It has an in-
tegral VDU interface—just plug a black and white television into the
system in order to provide a display unit—you do not need to buy
a separate terminal. The integral VDU interface gives you upper and
lower case characters and low resolution graphics. Text and graphics
can be mixed anywhere on the screen. The 380Z also has an integral
cassette interface, software and hardware, which uses named cassette
PRACTICAL COMPUTING September 1979
files for both program and data storage. This means that it is easy
to store more than one program per cassette.
Owners of a 380Z microcomputer can upgrade their system to
include floppy (standard or minl) disk storage and take full advantage
of a unique occurrence in the history of computing—the CP/MTM*
industry standard disk operating system. The 380Z uses an 8080
family microprocessor—the Z80—and this has enabled us to use
CP/M. This means that the 380Z user has access to a growing body of
CP/M base-software, supplied from many independent sources.
380Z mini floppy disk systems are available with the drives mounted
in the computer case itself, presenting a compact and tidy installa-
tion. The FDS-2 standard floppy disk system uses double-sided disk
drives, providing | Megabyte of on-line storage.
Versions of BASIC are available with the 380Z which automatically
provide controlled cassette data files, allow programs to be loaded
from paper tape, mark sense card readers or from a mainframe. A
disk BASIC is also available with serial and random access to disk files.
Most BASICs are available in erasable ROM which will allow for
periodic updating.
If you already have a teletype, the 380Z can use this for hard copy or
for paper tape input. Alternatively, you can purchase a low cost
380Z compatible printer for under £300, or choose from a range of
higher performance printers.
*CP/MTM Registered trademark Digital Research.
380Z/16K System with Keyboard £965.00
380Z/56K complete with DUAL FULL FLOPPY DISK SYSTEM
FDS-2 £3,266.00
380Z Computer Systems are distributed by RESEARCH MACHINES,
P.O. Box 75, Chapel Street, Oxford. Telephone: OXFORD (0865)
49792. Please send for the 380Z information Leaflet. Prices do not
include VAT @ 8% or Carriage
@ Circle No. 149
33
Professional
ASCII
—.
He araie
%* Intended for professional micro-processor applications.
* This one Keyboard wiil meet most present and future
requirements.
*® Full 128-character ASCII 8-bit code.
* Tri-mode MOS encoding.
* Applications notes for auto repeat, numeric pad,
serial output.
Upper and lower case characters generated by keyboard
with latching shift-fock. :
Selectable polarity.
Size 305 x 140 x 32mm. (12% x 5% x Min)
MOS/DTL/TTL compatible outputs.
New guaranteed OEM grade components.
Needs +5 and —12V supply.
Board has space for small low cost DC/DC converter so
that entire unit operates off single 5V rail.
Alpha tock.
Extra loose keys available.
Supplied complete with full technical data.
Rugged mil. spec. G—10 PCB with plated through holes.
2-key roll-over.
DC level and pulse strobe signal for easy interface to any
8-bit input port microprocessor system, video display or
terminal board.
w Strobe pulse width 1 ms.
*% User selection of positive or negative logic data and
strobe output.
¢+e be + *
+e 6 + %
Model 756 ASCII Keyboard. Fulty assembied
Two or more
Model 756 MF * 0
with metal mounting frame
Edge Connector, gold plated. Type 756/con
Numeric keypad. Type 710
Plastic enclosure, black. Type 701
OC to DC converter, for —12V Type DC512
U.K. orders add |VAT on order total.
Generous D.E.M. & distributor discounts available
Stockists required in some areas.
are, Middx. HAS 7EP, England.
Me CARTER
[| _/KEYBOARDS
@ Circle No. 150
34
PROGRAM NAME
TO RUN IN x] DATE
MACHINE
QUALITY
DATA
CASSETTE
MICRODIGITAL LTD
LOOK FOR THE LABEL!
The Micro-Digital ‘‘own-brand’’ C15 Cassette means high
quality, specially made for your micro-computer.
% Tape made against DIN reference tape 45513/ 16
C528V with anti-static carbon additive.
¥ Five screw case fixing and transport mechanism using
precision stainless steel roller axles.
¥ Two special graphite impregnated slip shields guide
tape edges to prevent pack scramble and dispel
residual static.
10 quality C15 cassettes with Fs A
library cases & special labels £ ro)
MICRODIGITALLTD
25 Brunswick St., Liverpool L2 OBJ. Tel: 051-236 0707
(inc. VAT
&P +P)
@ Circle No. (51
MICRO 44
Announces their New Range of
EXIDY SORCERER
SOFTWARE
Also customised programming
and software consultance
and support on all micros.
Contact Andy Marshall at:
MICRO 44, 44 Arthurs Bridge Road,
Woking, Surrey or
Phone: (04862) 66084.
@ Circle No. 152
PRACTICAL COMPUTING September 1979
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
Ex-Stock .. . For A While Anyway!?!
@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.
eMAKES EXCELLENT DISTRIBUTED PROCESSING COMPUTER 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 ASCII 128 Set With Limited Graphics; 64 User
Definable Function Keys, Programmable Cursor & Reverse Video
025 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
@Ali 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
tYes, That's the ONE-OFF Price, NOT the Delivery Date!?!
“Registered Trade Mark of Digital Research Corporation of California USA
@ Circle No. 153
PRACTICAL COMPUTING September 1979 35
36
GEMSOFT
are very pleased to announce their new
products and services
DISK-BASED BUSINESS
PROGRAMS FOR THE
PET
(1) Mail List: Up to 450 customers per disk; will print out on labels or
the screen and/or delete any customer at any time. £35 + VAT
(2) Current Account Package: Enter data from cheque stubs or bank
account and this program will analyse the account into six inputs
and 30 outputs, and print the results. Replaces writing-up the
books. £60 + VAT
(3) Sales Ledger. Prints invoices and statements, provides complete
list of transactions, sales figures, cash flow, outstanding debts, etc.
1,000 per desk. £85 + VAT
(4) VAT and General Accounting Package: Stores all VAT figures,
summarises cashflow, works out the VAT 100 form, etc.
£85 + VAT
(5) Invoice Program: Prints invoices, works out totals of varying
amounts of items, adds or deducts, discounts , VAT, etc.
£35 + VAT
(6) Order Forms: Similar to invoice program. £30 + VAT
Under development. Employment agency package, estate
agents’ package, hotel management, and several more.
Available on the Commodore or Computhink Disk Systems.
All programs can be individually customised by us for
your own particular application. We specialise in bus-
iness software for all applications. Please contact us for
further information or a demonstration.
Pet Software: The Gemsoft Catalogue now contains nearly
70 titles of interest: games, educational, scientific, business,
etc., at prices from £3.80.
Exidy Software: The new Gemsoft Exidy Catalogue has
nearly 20 titles available; a selection of games and general
programs at very reasonable prices. For either, or both catalo-
gues, send s.a.e. to the address below.
Hardware: We sell complete systems, Pet 2001, Com-
modore and Computhink Disk Systems, Anadex Printers,
etc., as well as all the software to get your business up and
running in the most economical manner.
Please contact Tony Dawe, Nick Dunn, or Nigel Tyler at
Gemsoft:
ALVERSTONE LODGE, WYCH HILL LANE, WOKING,
SURREY
Tel: (04862) 60268
DEALER ENQUIRIES INVITED
@ Circle No. 154
MULLIONS
YARWELL
PETERBOROUGH
9
Fr. echnic
computer
consultants
Hardware by
EQUINOX
SWTPC TEXAS
DIABLO
SOURCE (UK)
ACCOUNTS: PARTS : MAIL: SBASIC CFOR SWTPC SYSTEMS)
Software by
One Day Courses each Month
e Introduction to Micros.
e Business Applications.
PROTECHNIC
O780- 782746/ 782913
@ Circle No. 155
Mol MINE OF INFORMATION LTD Mol
1 FRANCIS AVENUE, ST ALBANS AL3 68L ENGLAND 9 PHONE 072757801 TELEX 925859
MICROCOMPUTER CONSULTANCY & BOOKSELLERS
CHOOSING A
MICROPROCESSOR?
10800 6512 8080A COSMAC
1650 6513 8085A CP1600
1802 6514 8086 F8
2650A 6515 8741 1M6100
2901 6701 8748 INS8900
3850 6800 8749 MC2
3870 6802 8X300 microNOVA
PACE
SC/MP
TMS1000
280
6502
6503
6504
6505 8048 9980A
6506 8049 9981
Details and opinions of the above microprocessors (registers,
addressing modes, status flags, pins and signals, instruction
timing and execution, instruction set, benchmark program,
specific support devices to the same level of detail, data sheets)
are clearly laid out for easy comparison in a looseleaf book’
published in California, the birthplace of the microelectronics
industry.
Mine of Information Ltd is offering this valuable reference work.
for only £14.00 post free—add £1.00 for delivery outside the UK.
Binder £3.50 extra; update service available.
Introduction To Microcomputers by Adam Osborne & Asso-
ciates Volume 2: SOME REAL MICROPROCESSORS (Sept 1978)
1373 pages, 405 figures, 254 data sheets, 25 chapters £14.00
8021
8035
8041
9440
9900
9940
@ Circle No. 156
PRACTICAL COMPUTING September 1979
AUTHORISED
PET
COMMODORE
DEALERS
Birmingham
Camden Electronics
021-773-8240
CPS (Data Systems)
021-707-3866
Taylor Wilson Systems
Knowle (056-45) 6192
Bolton
B & B Consultants
0204-26644
Bournemouth
Stage One Computers
0202-23570
Bradford
Ackroyd T/W &
Add M/C
0274-31835
Brentwood Essex
Direct Data Marketing
0277-229379
Bristol
Bristol Computer Centre
0272-23430
Sumlock Tabdown
0272-26685
Cambridge
Cambridge Computer
Store
0223-68155
Cardiff
Sigma Systems
0222-21515
Colchester
Dataview Lid
0206-788 I!
Derby
Davidson Richards
0332-366803
Durham
Dyson Instruments
0385-66937
Edinburgh
Micro Centre
031-225-2022
Exeter
A.C, Systems
0392-71718
Grimsby
Allen Computers
0472-40568
Hemel Hempstead
Data Efficiency
0442-57137
Hove
Amplicon Micro Systems
0273-7207 16
Leeds
Holdene
0532-459459
Liverpool
Dams Office Equipment
051-227-3301
London N14
Micro Computation
01-882 5104
Rockliff Bros
051-521-5830
THE
PET 4K
COMPUTER
at
£450 evar
it’s got to
be
Britains
hest buy!
Personal
Computer
Professional
Printers
High specification printers can
print onto paper all the PET
characters — letters, numbers and
graphics. A tractor feed model has
the advantage of accepting mailing
labels, using standard pre-printed
forms. The only connections re-
quired are an A/C lead and PET
connecting leads. The PET is
Programmable, allowing the prin-
ter to format print and it accepts
84" paper giving up to fourcopies.
Dual Drive
Floppy Disc
The Dual Drive Floppy Disk Is the
latest in Disk technology with
extremely large storage capability
and excellent file management.
The Floppy Disk operating system
used with the PET computer
enables a program to read or write
data in the background while
simultaneously transferring data
to the PET. The Floppy Disk is a
retiable tow cost unit, and is con-
venient for high speed data trans-
fer. Due to the latest technologicat
advances incorporated In this disk,
360 Euston Road. London.
PRACTICAL COMPUTING September 1979
Why the PET is the number one
The Self Contained PETS
The self contained PET models
2001-4 and 8 come complete with
TV screen, keyboard and built-in
cassette deck as well as the
computer circuitry. They are
simply plugged into any 13 amp
mains and no special knowledge is
needed for running standard pro-
grams — over 200 of which are
available on cassettes.
a@ total of 360K bytes are available
in the two standard 5¥,” disks.
Only two connections are neces-
sary an A/C lead and PET
interface lead
Software and
application
areas for PET
There are a targe number of
programs that can readily be used
with the PET. Personalised pro-
gramming is available from many
Authorised Dealers. Over 200 pro-
grams are now available from
Commodore and other software
suppliers for the PET. Popular pro-
gram titles include Stock Control,
Statistics, Payroll, Strathclyde
Basic Course, Chess, Lunar Land-
Ing and Education Packs.
FOR THE COMMERCIAL USER
The Commodore PET offers for
the first time a really cost effective
business computer for use in
Accountancy, Statistics,
Stock Control, Payroll,
tnvolcing etc
PETBOOM
IN BRITAIN
The Big Memory PETS
The BIG MEMORY PETS contain
the same main features as for the
2001-4 and 8 models except that
they incorporate a full typewriter
size keyboard and have larger
internal memory of 16K and 32K
bytes RAM respectively.
FOR THE SCIENTIST AND THE
LABORATORY
PET has a comprehensive set of
scientific functions making it a far
superlor tool to the best program-
mable calculators. PET interfaces
directly with hundreds of labora-
tory instruments. PET is an ideal
industrial and commercial con-
troller.
FOR THE EDUCATIONAL
WORLD
The extensive basic language
makes PET an ideal tool for
teaching computer programming.
Programs can be written to “tutor”
the user (pupit) in almost any
discipline, including BASIC itself.
And, of course, the PET can be
used to take care of school
records, exam results, attendance
figures etc.
IN THE HOME
The PET is an extremely creative
and instructive learning medium of
the future for young and old alike.
There are also large numbers of
entertainment programmes avail-
able including chess and space
games.
7¥ Phone about PETnow!
CALL YOUR LOCAL AUTHORISED DEALER or in case of difficulty contact:
COMMODORE SYSTEMS DIVISION
Tel: 041-388-5702
London E2
Ragnarok Electronic
Systems
01-98 1-2748
London EC1
Sumlock Bondain
011-253-2447
London NW4
Da Vinci Computers
01-202-9630
London SW14
Micro Computer Centre
011-876-6609
London WCI1
Euro-Cale
01-405-3113
London WC2
TLC World Trading
01-839-3893
Manchester
Cytek
061-832-7604
Sumlock Electronic
Services
061-834-4233
Matlock
Lowe Electronics
0629-2817
Morley, W. Yorks
Yorkshire Electronic
Services
0532-522181
Norwich
Sumlock Bondain
0603-26259
Retien «i
Betos Systems0602-48108
Oxford ,
Orchard Electronics Ltd
Wallingford (0491) 35529
Plymouth
J.A.D. Integrated Services
0752-62616
Preston
Preston Computer Centre
0772-57684
Reading
CSE Computers
0734-61492
Southampton
Business Electronics
0703-738248
Symtec Systems
0703-37731
Sunderland Tripont
Associated Systems
0783-73310
Petalect
04862-69032
Yeovil
Computerbits
0935-26522
North Scotland
Thistle Computers
Kirkwall (08 56)-3140
Northern Ireland
Medical & Scientific
Lisburn (08462)-77533
@ Circle No. 157
37
We are North Microcomputer
London dealers sales and
for the best software.
micros on the
market.
\f youneed adviceon which Microcomputertobuy WECANHELPYOU.Wearespecialistsin (fg\ n=":
writing packages and tailor-made software.
MICROSTAR 45, below, from £4,950 64k RAM, 1:2M or’ APPLE Il, right, (ITT
2°4M char. disc storage. MULTI-USER, MULTI-TASK, 2020) from £830. A ~
database reporting system. A complete system for £6,000— | complete business system ee) ene
£7,000. including printer and See
software. All for
under £3,000. SOFTWARE
APPLE || MICROSTAR
Stock control £100 Stock control/£500
Purchase ledger £275 Sales ledger
. Invoicing/Debtors ledger £275 Word processing £300
A, Payroll (up to 200 employees—I.R. Payroll £250
4 approved) £175 incomplete Records £750
1 Incomplete records £250 Other software on request
uy Medical Billing/case history £300
a { Equipment rental £250
Y _ t Financial modelling £275 Come and see the computer
a =. School commerce and Physics teaching and discuss your
A package £150 each requirements.
Sy Chequebook £20 We promise a personal
— service
SF t: M PRINTERS H.P. or leasing available
A large selection available. The new
LOW COST PRINTERM now in stock:
120cps, 80 columns, serial/parallel
= interface, 9x 7 matrix, £695
MICROSOLVE COMPUTER SERVICES LIMITED, 2nd floor, 125-129 High Street, Edgware, Middx. Tel 01-951 0218
@ Circle No. 158
New Low-Cost ASCII Keyboards-Ex Stock Delivery
KB756 56-keystations, Mail order total
mounted on PCB £49:50 £55.08
KB756MF, as above,
fitted with metal
mounting frame for extra
rigidity £55.00 £61.02
Optional Extras:
KB15P Edge Connector f£ 3.25 £ 4.05
KB701 Plastic Enclosure £12.50 £14.31
KB702 Steel Enclosure £25.00 £28.62
KB771 — Latest addition to the range — ideal for the VOU-builder 71
Keystations incorporating separate numeric/cursor controi pad and
instailed in a custom-built steel enclosure with textured enamel finish
Case dimensions: 17%" x7%" x 3°," Total weight: 4Kg
Quantity discounts
available
KB710 Numeric Pad £ 8.00 £ 9.18
= — ccvwntwsttmgumemeens | KB2376 Spare ROM
= eat ¥ — Encoder £12.50 £14.04
Price £95.00 (mail order total £108.00) 25-way | 9C-512 DC/DC thaaboue
D-Type connector for {B771 £4.25 (mail order total | Converter f£ 7.50 £ 8.64 keyboards are
fully TTL-compatible,
Providing the full 128 ASCII
character set, and requiring
+5V —12V Power Supply.
Full technical data and
circuit diagrams supplied
£5.13)
NEW KEYTOP/
KEYSWITCH KITS — ASCII
CHARACTER SET BRAND
NEW SURPLUS
Pack of 58 keytops and keyswitches comprising 49 “Qwerty” set TTY
format + 9 Edit/Function keys
PRICE: £15.00 (mail order total £17.28)
SEALECTRO PATCH BOARDS
Programme boards for switching and interconnecting input/output circuits.
11% 20 XY matrix. Interconnection ts by means of shorting Skip and component
holding pins (not included). Dimensions: 72" x5% :
PRICE: £12.50 (mail order total £14.58)
Recon-
dttones EDITING VDU SAVE £100!
HAZELTINE H-2000A Superb specification includes full
NOW ONLY £395.00 edit capability, direct cursor
HAZELTINE H-2000B addressing, standard V.24 (RS232)
NOW ONLY £495.00 __ interface. 90 days’ warranty.
*® Teletype Compatible # Switch-selectable Parity
ae ne ee wad
* Ui
NEW SHUGART * ZoeolMenwaers 4 Dreet Cuso Adossing i
FLOPPY DISC DRIVES « 5x7 Dot Matrix *® Detachable Keyboard
# 5 Switch-selectable Transmission. # Printer Port indice
Speeds up to 9600 baud. *% 90-day Warranty
We also specialise in: DEC minis PDP8 and PDP11 processors, add-on memory, peripherals and spares.
Hard copy terminals — ASR33 and KSR 33 Teletypes, Data Dynamics 390, Texas Silent 700. Send for complete lists.
A copy of our
“sm | fm = Electronic Brokers
supplied on
request. 49/53 Pancras RoadLondon NW1 2QB Tel: 01-837 7781. Telex 298694
@ Circle No. 159
38 PRACTICAL COMPUTING § September 1979
$A400 Minifloppy — 110K6 capacity. 35 tracks, transfer rate
125K bits/sec. AV access time, 550msec. Power requirements
+5VDC + 12V0C.
PRICE: £195.00
SA800 Floppy 400 KB capacity. 77 tracks, transfer rate
250K bits/sec. AV access time 260msec. Power requirements + 24DC
+5VDC SVDC.
PRICE: £395.00
1N914
1N4005
‘DIODES/ZENERS
Cc MOS
4000
QTy
1N4007
1N4148
10mA
1N4733
1 W Zener
QTy.
LM323K«
LINEARS, REGULATORS, etc.
QTY.
LM380 (8-14 Pin}1.19
COMMERCIAL AND MANUFACTURING ACCOUNTS INVITED
ALL PRICES IN U.S. DOLLARS. PLEASE ADD POSTAGE TO COVER METHOD OF SHIPPING.
ORDERS OVER $100 (U.S.) WILL BE SHIPPED AIR NO CHARGE.
PAYMENT SUBMITTED WITH ORDER SHOULD BE IN U.S. DOLLARS.
ALL IC’S PRIME/GUARANTEED ALL ORDERS SHIPPED SAME DAY RECEIVED.
Phone (714) 278-4394
CREDIT CARDS ACCEPTED:
PRACTICAL COMPUTING September 1979
BarclayCard / Access / American Express / BankAmericard / Visa / MasterCharge
IN753A 6.2v 500 mW Zener 25 LM309K (340K-5) 1.50
IN758A 10v se 28 | LM310 85
1N759A l2v " 25 LM3110 75 LM340K12
__1N5243 13v_ Fr 25 | LM318 1.75 LM 340K 18
1N5244B 14y 3 5 LM320H6 u K
ees 15y = 75 | LM320H15 LM340K24
a : ez LM320H24 LM373
awl SOCKETS/BRIDGES LMDOKT?
8-pin pcb .20 ww 35 LM320K24
Tani 7 70 40 LM320T5
(f= fetal [29 2 We 2 LM320T12
16-pin ecb .20 5 ww .40 LM320T15
18-pin ecb .25 ww .95
2 20-pin pcb 35 ww 95
22-pin ecb 35 ww .95 -_ nr rek = &
|p r QTY arty aty YY.
L 24-pin Bet a My ses 700010 78275 74221 1.00 miso? 30
} 28-pin a us aor 1S | 7483S 7436795 7isod 30
40-pin pcb 50 ww 1-25 70215 mes 55 | ~SC«STOBA 35 74180535
Molex pins .01 To-3 Sockets .25 7403 15 7486 25 75491 50 74LS08 35
2 Amp Bridge 100-prv .95 7404 10 7489 = 1.05 75492 —.S0 74LS09 35
25 Amp Bridge 200-prv 740525 7490 45 74H00 18 : 74LS16 35
7406 2 7491 70 74401 20 Mist! 35
a TRANSISTORS, LEDS, etc. 7407 55 : ets 2 Ne 2 aw =
j 7468 15 74 3 HOS” ; a5
L 2N2222 (2N2222 Plastic .10} ats 7409 1 7494 15 74H08 35 T4LS22 35 |
2N2222A i9 ; 7410 5 7495 «60 “74H10 35 741$32 35
ay ENE a TE 7411 25 7496.80 TaH1) 25 74153? 35
N astic Unmarked P T4H1 4 741538. 45
2N3904 NPN (Plastic Unmarked) _.10 4035 75 Le) 74100 1.18 id : a = = =
2N3054 NPN 45 4037 1.80 7403 25 74107 25 20 J L
2N 3055 NPN 15A GOv a) . 7414 75 74121 35 74H21 as] 74LS42 WS
T1°125 PNP Darlington Tae 4040 7416.25 7412255 TaW22___ 40 Tauss1 45
[ LEDGreen, Red, Clear, Yellow 15 =i m7 40 | atz3, 35 4H3020-+| —=CTALSTA OS
D.L.747 7 seg 5/8" High com-anode!.95 _| 4042 F820 owe PAV25 0 Mass POH AD al TS Dei)
lig MAN72____7segcom-anode (Red) 1.25 4043 M263 7412635
MAN3610 7 seg com-anode (Orange) 1.25 4044 i 7427 25 7413278 7H51 25 741590 =
MANB2A 7 seg com-anode (Yellow) 1.25 046 1.25 7430 15 74141 90 74H52 15 74.893 65
lara MAN74 ___7.seg com-cathode (Red) _1.50 4048 743220 74H53_25 7aisi0? 50
Pe FNO359___7 seg com-cathode (Red) 1.25 4049 7437 20 [| sats 5 | 7aHSS 20 | 74L8123 1.20
, 74193 75 74H72 35 74L$151 __ 85
9000 SERIES 4050 35 TanTé 35 __Tatsis3 85
aty ». Sie oade 70 7T4H101 75 T4L5157
|e __“9804 : 7418355 TLS 160
L 9309 35 2601 4066 55 74161 TAH106 74.8164 1.20
{Se — 4069/74C04 35 vag a nia _ as
I ; ; 7445 65 a1 60 L
MICRO'S, RAMS, CPU S, E-PROMS 7486 pats, 110 74L§244 1.70
QTY. ,
as 1.50 | a | 7487 70 78166 1.25 74.$367
BT23 1.50 2114 357] t P 7448 50 74175 80
[ 8T24 2.00, . 2513 6.25 | asd pais
8197 1.00 2708 10.50
[ 748188 3.00 | 2716 DS. 34.00 4512 —_—*12.10 TaTeY 2.25 Tata7 195 74803 25
if 1488 1.25 2716 (Sv) 59.00 | 4515. ~«-2.95 Ta182 745i 45 74504
1489 1,25 2758 (5v) 23.95 4519 S13 74190 1.25 74155 5 74805
(a L720 4.50 3242 10.50 |} : 78191 1.25 T4L72__.4S 74508 35
[_ AM9050___4.00 4116 11.50 7419275 7417340 74$10 35
6800 13.95 47325 7819385 74L74__ AS Wasi 35
MM 5314 3.00 _| eae 7.95 | 1474 4 7419495 M4L75 85 74820 25
{ MM 5316 3.50 | 080 7.50 7475 35 74195 95 7493.55 74840 20
MM 5387 3.50 8212 2.75 — = Lar ; art 7aRSO 5
— Se a micas Ce = Ts
= 250) MC 14419 4.85
+ TH 16028 __3.98 are 34 74C151 1°50 7481 74198 1.45 TALSO1 30 74864 15
LED S14 ar 32 2 74574 35
a 22.50 6228 6.007 J —— m7
a € 80 17.50 8251 7.50 _| CABLE ADDRESS: ICUSD t etd ec
“Z80PI0 10.50 | 8253 18.50 - _ 85
a 2102 1.45 8255 8.50 TELEX # 697827 748133 40
2102L 1.75 | TMS 4044 9.95 eel SIIO 58
- : HOURS: 9 A.M.-6P.M. MON. thru SUN. 135151 io
; 748153 35
748157 15
745158 30
7889 Clairemont.Mesa Blvd. «© San Diego, California 92111 U.S.A. ee atin
NO MINIMUM Tee ee
SPECIAL DISCOUNTS
Total Order Deduct
$35-$99 10%
$100-$300 15%
$301-$1000 20%
l
@ Circle No. (60
39
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 U.K.:
TANDY TRS-80
COMMODORE PET
APPLE Il
N-S HORIZON
FOUINOX 300
A powerful multi-user
multi-tasking
multi-language
16-bit microcomputer time-sharing system
supporting
* BASIC
CROMEMCO USP
SORCERER ’ Floppy discs
~ Hard discs
including a powerful Text Formatter,
Assembly Language Development System
and disc-based Sort utilities
SUPERBOARD II
NASCOM-1
Where possible we deliver off-the-shelf. Our stock also
includes a vast range of electronic components as well
as computer books and magazines.
Priced from under £5,000
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.
Write or phone for further information.
EQUINOX COMPUTER SYSTEMS LTD
“Kleeman House” lo Anning Street.
New Inn Yard. London HC2A 3HB.
CAMBRIDGE COMPUTER STORE lel 01739 23879 01729 4460
1 Emmanuel Street, Cambridge (0223) 68155
@ Circle No. 16] @ Circle No. 162
Jeff Orr andGraham Knott are now offering:
AIM161
16 way
A/D Converters
£130
Analogue to
Digital conversion, Suitable for all
8-bit microcomputers
Connectors
available to suit most machines:
Pet, Apple, ITT, Aim etc.
-
‘ 400k on the
Pet £840
' directly interfacing
with 32k pet
200k on each drive
Random and sequential
access
Memory Expansi Interfaces _
pee eee I EEE to RS232 unidirectional £89
24k Expandamem for Pet £320 I EEE to RS232 bi-directional £186
16k Apple Ram up grade £85
625 video adaptors for Pet £25 complete
We also stock and supply Apple II, ITT 2020, Centronics,
Teletype, Anadex, Paper, diskettes, Cassettes etc.
ma. Pn, O51 924 1125 el
a cheques payable to
Stack Computer Services Ltd.
for details of our "
catalogue or write Stack Computer Services Ltd.
1 Westward View, Waterloo, Liverpool L22 6RB
~ . COMPUTER
: SERVICES wo.
@ Circle No. 163
40 PRACTICAL COMPUTING September 1979
G COMPUTRADE
AMOEBA} NeW
FROM
Tos
At the price of a sophisti-
cated VDU the AMOEBA
gives true intelligent
terminal capabilities.
Features of
AMOEBA
* 16k RAM
* Z80 processor
* Integral 12 inch
VOU
* RS-232 ports
* Built in micro
cassette
{60k bytes)
* High fevel Edito
plus BASIC
* 2708 compatible
Acoustic data
modem speeds up
to 300 bauds—
works either at the
computer or
terminal end of
a datalink
COMPACT 3
The VDU that
fits most micro,
mini and main-
Kem,
—
7
~<
. Ae a
INTERTUBE
SUPERBRAIN
As a Smail Business micro
system or intelligent
terminal, SUPERBRAIN
provides the answer.
4)
Features of Paved
SUPERBRAIN
+ 64k RAM fe:
* 320k bytes!s; -
Disc storage
(expandable)
* CP/M with BASIC,
FORTRAN, COBOL
and APL
* S 100 BUS
* Twin Z80 processors
* RS-232 (V24) ports
The portable
hard copy
terminal that’s
built to fast—
thousands of
satisfied users.
OUCE:
4360
Feature packed INTERTUBE
w 24 «80 upper and lowercase
® Highlighting
+ Reverse Video
» Protected Fields
# Line Drawing
® X/Y Cursor addressing
* Conversational, Message, Page modes
* Word or line insert/delete
© 25th Status line
AS232 Proter por with
wndependent Baud sate
Probably the best
value 80 col, 112
cps printer on
the market
Now has variable
width sprocket feed
and 1000ch Buffer
as standard.
® Self Test
® Line Drawing
28 Programmable function
keys
# RS232 of Current Loop
w Separate Numenc Pad
GREA
COST
PERF ORMANG
FANTASTIC
PICTURE
QUALITY
frame systems—
lots of built in
features
CUB
An economic
answer to
simple VDU
needs,
64 x 16ch,
cursor control
Write or call for details:
Computrade Ltd
Silverwood House, Oxshott Rd.,
Leatherhead, Surrey
Tel (03723) 79143
South West 01-673 3322
West 0258-72946
North 061-477 4960
Midtands 0533-536077
South East 01-658 5906
hot line 03723-77066
@ Circle No. 164
PRACTICAL COMPUTING September 1979 4)
BUY Zilog
...NOT JUST Z80
ZILOG microcomputers for solutions to
business problems
A lot of microcomputers use our Z80 CPU but only Zilog supplies the
MCZ-1 family of microcomputers
Did you know that Zilog, inventors of the Z80 microprocessor, also manufacture high-performance microcomputers
supported with high-power quality software and full maintenance in the U.K.?
Zilog computers range from low-cost, portable desk-top units with twin floppy disks to 10 megabyte cartridge disk
systems.
This software-compatible MCZ-1 family supports our proven R10 operating system and five popular high-level
languages.
@ COBOL @ PASCAL @ BASIC @ PLZ ® FORTRAN
Available applications software packages include Order Entry, Payroll, Purchase Ledger, Sales Ledger, Nominal
Ledger, Stock Control, Text Formatting and many more.
‘The MCZ-1 family is ready to start working for you today. From Zilog — the company which brought you the 280 —
the company dedicated to stay a generation ahead.
Call today for further information.
Y
S| Zilog (U.K.) Limited, Babbage House, King Street,
; Maidenhead, Berks SL6 1DU.
Zilog Telephone (0628) 36131
@ Circle No.. 165
42 PRACTICAL COMPUTING September 1979
WE HAVE five computers in and around the Practical Computing
office. At the time of writing, only one is working. To give
credit where credit is due, that one is the Pet. What of the
others?
We have a £2,000 household name system which is supposed to
be doing a useful job in the office. For many weeks, nothing
has emerged from it but garbage and the sour smell of burnt
ROM. It has been twice already for repair and will
no doubt soon be making the journey a third time. We have a
second household name with discs. Sometimes it loads, some-
times it doesn’t. ‘‘Put your finger in the hole and stir’, say its
masters; we stir and it loads not.
For three days we have been trying to get another cheap but
trendy computer to drive a popular matrix printer. Those days
have been filled with endless three-way telephone con-
versations between the computer people, the printer people
and ourselves.
One says one thing, the other something different, but it is of no
importance — the machine gives not a click. Then a colleague
pulled the computer power plug out of the wall accidentally
and ended the debate, for now the machine will not work at
all.
We have a mini which behaves reasonably well, as it should,
considering how much it cost, but on some days it gets into a
loop and has to run through its half-million irrelevant cal-
culations before it will re-emerge several hours later into the
real world.
Even if the machinery were working correctly, would we be
happy? That is a big question and the answer for today must
be in the negative. If the machinery is fragile, the software it
runs is worse. The Pet works but the batch of sample tapes we
are trying from a major software supplier often do not.
We have a good Life game but there are certain input patterns
which lock-up the screen and the only remedy is to re-load.
The business system alleged to be running on the second
household name has no visible escape from many of its
routines. It will sit, showing what you don’t want to know, its
discs buzzing and clicking like demented chickens, and no
combination of keys will budge it.
In the wider world, some canny fellow has offered a prize of
£100 for a British business system running on a mic-
rocomputer which will run for a month, or perhaps a week,
without crashing. We think he may not have to pay in the
foreseeable future.
Even programs which run are subject to problems. For instance,
we published a Zombie game in our June issue. It was written
in Basic on a PDP, and you would think that since Basic is a
universal language, anyone who wanted to use it could do so.
Yet the office telephones rang for a month with the plaints of
unhappy readers who could not get the wretched thing to run.
The trouble, as it emerged after many aggravating hours, was
in the random number generator. There are dialects of Basic,
and one machine’s RND is another machine’s poison.
The whole thing puts one in mind of the early days of motor cars
— well, what one has been told about them, since we're not
that ancient. Cars then were very like microcomputers now.
There were dozens of different kinds, allied only by their unre-
liability, incompatibility and the fanatical enthusiasm of their
owners.
‘Those owners would speak disparagingly of ‘horse and buggy”
ideas and would happily spend six hours travelling six miles
PRACTICAL COMPUTING September 1979
retrieving — as Kipling so movingly describes in one of his
stories — the contents of a ball-race dropped along six fur-
longs of un-metalled road.
Well, so it is now. The difference is that the fans of mic-
Editorial aaa
The Real World -
because they had had the fun of fitting new big ends after the |
second mile, re-wiring the ignition after the fourth and then |.
rocomputing have a more gullible public. Many people are |
being persuaded to ride in our new bangers. They are holding |
their hats and waiting for the big thrill. It may come, or, what
is more likely, the whole mess of machinery may blow up,
cover all concerned with hot oil and sit lifeless by the road-
side.
In plain terms, microcomputers and their software are not yet
robust enough for the rea! world. At best, they are being built
and sold by people who are fascinated by them, take great care |
how they use them, and expect others to do the same.
There is, of course, also a fair share of cowboys who do not care
about these things, but we shall not mention them. The trouble
is that the population of micro-freaks, who have the brain |
power to wrestle with raw micros, is almost used up. If our
industry is to develop, the machines must be sold to people
who want answers to their problems, not more problems still.
So far we have managed to make micros do more or less what we
want. What we have not yet done is prevent them doing what
we do not want, and there is a huge difference between these
two states of affairs. For, if there is one way of doing some-
thing correctly, there are a hundred ways of doing it wrong.
If it costs £1 to make the thing which works correctly sometimes,
it costs £10 to make it work most days and £100 to make it
work properly always.
That is particularly true of software. Any intelligent fool can
write a program to add a firm’s invoices and deduct 15 per-
cent tor VA. It takes a clever chap to write a program
which will load and run, time after time; which will not crash
or lock up no matter what silly key Minnie the office mouse
hits. But it must come.
Next month — Teletext
In a roundabout way, that leads us to the subject of next month's
delights. In the October Practical Computing we shall be
devoting a good deal of space to the important subject of
Teletext, or data-at-a-distance.
We shall look at the dissemination of software by television
and wire, at Ceefax, Oracle and Prestel; at the coming gen-
eration of home data stations with micros built into television
sets, which can take-in data and programs from central banks,
or transmit them back along the line to friends, colleagues or
for general use.
We shall be looking, in short, at the techniques and hardware
which will link the many individual micro-revolutions into one
— which may well, in time, disperse cities and jobs as we know |
them today.
It seems likely that the most important effect of this develop-
ment for Practical Computing readers will be to create a vast
new market for software. Reliable, never-crash software. It
may be that many people who are now hobbyists wil! work
full-time at home, writing programs to satisfy this market and
having a better life than they do now. We hope so, anyway
PROGRAM OF THE YEAR COMPETITION
This competition has now closed, slightly late because of postal problems, and we are happy to report a heavy crop of
entries — at first glance of a high standard. It was not possible to do them justice in time to include the results in this
issue. All entrants will be informed of the results by post and we hope to announce them in the October issue.
43
All Systems Are Not
Your computer application is unique. It
differs from all others. It is because not all
applications are equal that MSI has de-
veloped a variety of computer systems.
At the heart of every MSI System is the
powerful MSI 6800 Computer, one of the
fastest and most versatile available. De-
pending on the System you select, the MS!
6800 has from 16K to 56K of RAM. Mass
memory storage in MSI Systems range from
315K bytes in the System 1 to over 10
megabytes in our most powerful System 12.
in addition to the computer and memory
subsystem, MSI Systems include a CRT
terminal and high speed character printer.
The System 12 is housed in a compact desk
unit.
44
reated
-
e
doe Bee
As with hardware, computer software is
not always created equal. Since there are a
myriad of programs available, MSI offers a
choice of Operating Systems for use with
your MSI Computer System. Of course, our
favorite is MSIDOS, but we offer the
powerful SDOS operating system as well.
All MS! Systems wil! support the other
software products associated with each
operating system.
MSI also has a variety of software
programs including a complete Accounting
Package and a Multi-User Basic program
capable of supporting up to four users.
MSI Systems are currently being used in
a broad spectrum of personal, scientific,
educational, professional and business
met ss
el i
fee
be iad
Me sy
situations. In addition to our Systems, we
can supply you with individual components
for personal and OEM use. All MSI System
components are available, some in kit form.
Write or call us for more information
about MSI Systems and products and the
name of your nearest MS! dealer.
STRUMECH ENGINEERING,
ELECTRONIC DEVELOPMENTS,
PORTLAND HOUSE,
COPPER SIDE, BROWNHILLS.
(0827) 4321 TLX 335243
@ Circle No. 166
PRACTICAL COMPUTING § September 1979
eee ee ee
Suggestions
1 AGREE with C Bowden's comments in the
June issue and would further like to suggest
articles which I, and many of my colleagues,
would find valuable.
Assembly languages. A series covering
programming techniques, perhaps using the
6502 and 808A derivatives as the basis for dis-
cussion. A short summary of the basic instruc-
tions and their use in simple routines, increas-
ing gradually, should be included, together
with flowcharting techniques and their
implementation in assembly code. Perhaps the
series could be moulded around a specified
project, such as designing a Nascom-type
monitor.
Systems software. Covering the principles of
monitors, bootstrap loaders, assemblers and
common start-up procedures. The series
should explain how the software works, why
the various techniques are used, and how they
are tailored to the hardware.
Hopefully the reader should be able to write
his or her own having read the article(s). It
would be linked to specific micros, e.g. Kim,
Elf, Superboard II, to provide the ‘10K of
your own EPROMs holding self-developed
functions” Vincent Tseng mentioned in his
Superboard Review.
Hardware design. From the basics of
Boolean algebra to TTL logic, leading to the
construction of I/O structures and memory
units. Simple examples and diagrams should
be included, and the series could be based
around, for example, designing a memory
expansion of a commercial system — Kim, EIf,
Nascom, Superboard.
Business applications. When contributors
describe their implementation of a system,
instead of the generalising on the principles
used, I am sure flowcharts, file structures, and
program coding would be of more value to
readers.
Program codings. When they are repro-
duced, they are frequently difficult to
decipher. If they could be re-set and printed as
the tips in the Pet and TRS-80 pages instead of
being reproduced from computer printouts Pm
sure legibility would improve.
I hope these comments prove of value, and
would like to thank you for an excellent, com-
prehensive magazine.
M. G. Walker.
@ Since this is a fully-interactive, hands-on
magazine, would any readers like to rise to the
challenge and write the articles suggested? We
should say, in self-defence, that we reproduce
listings from printouts because experience
shows that re-setting them into something
more legible can cause mistakes.
Rental charges
WITH the advent of relatively cheap silicon chip
technology, the price of microcomputer sys-
tems has fallen dramatically over the last year.
I am sure that we are all aware of the pro-
liferation of micros in the £300-£600 bracket
— notably the Pet and TRS-80 — which can
be obtained almost as easily as buying a tele-
vision, however far from civilisation one lives.
What I would like to know — and until now
1 haven’t received a suitable answer — is
why the hire charges for renting a small com-
puter are so incredibly high? After all, one
does not need to deposit £150 plus approx-
imately £5 a day to rent a £450 luxury colour
*PRACTICAL COMPUTING September 1979
Our Feedback columns offer readers the opportunity of
bringing their computing experience and problems to the
attention of others, as well as to seek our advice or to make
suggestions, which we are always happy to receive. Make
sure you use Feedback—t is your chance to keep in touch.
TV. So let us have an explanation for what I
believe is exploitation and blatant profiteering.
Martin Black,
Manchester, 8.
@ To be falr, TV rental companies can offer
low rates because they buy sets in huge quan-
tities at low prices. Also, TV sets are much
more robust than micros and easier to repalr.
There seems, however, some substance in the
complaints. Would any micro-renter care to
defend the position?
Not so difficult
IN HIS REVIEW of the CP/M operating system,
Roland Perry makes it sound far more difficult
to use than it really is. 1 have been using CP/M
Version 1.44 for a few days and I find it easy to
use, although it took an afternoon to master.
In particular, ED 1.4 — the text editor —
allows reference to absolute line numbers
within the text buffer, a feature which makes it
easier to use than other character-orientated
editors. The easiest way to change all occurr-
ences of GAMMA to DELTA is
#SGAMMAIZDELTA <cr>
where # is the shorthand form for a repeat
factor of 65535. Perry’s version will also type
the lines containing the new string DELTA.
My main criticism of CP/M is the way the
“rubout” is echoed as the character is being
deleted. For example, if FRAD is typed
instead of FRED, pressing rubout twice and
then entering the correct letters gives FRAD-
DAED. This is so difficult to read that typing
contro] — R will print the line as it appears to
CP/M (i.e. FRED). Implementing “rubout” as
a physical backspace, or backarrow for TTYs,
is much neater.
The difference between CP/M and other sys-
tems is like the difference between APL and
Basic; the investment in time to learn how to
use it pays off in long-term ease of use.
S. J. Withers,
Coventry.
Futile quest
THE ADVERTISEMENTS in your journal proclaim
that certain types of microcomputers are avail-
able but it is a very different story, and a very
frustrating one, when it comes to purchasing
the equipment.
I work for a research association and we
have been seeking two microcomputers, the
Kim and the Exidy Sorcerer, which were
widely advertised in the February and May
issues of your journal.
In respect to both systems, I have phoned as
many as six to eight suppliers asking if we can
purchase their advertised systems within a
reasonable delivery period. The answer we got
from the suppliers is “Sorry, we are waiting for
delivery and we don’t know when to expect
them” or “Sorry, we can’t supply within three
to six months”, or ‘“‘We are out of this part or
the other part”, and ‘“We cannot accept an
order as we cannot give you any definite date
of delivery”.
I find this disquieting; if something is adver-
tised, one would think it was available.
1 would be interested to know if any more
readers have met these ‘‘unavailable” products
which seem accessible until it comes to order-
ing.
M. G. Hummel,
Wantage,
Berkshire.
Supply and demand
SOME of your advertisers imply that they have
the articles they describe in stock. Very fre-
quently this is not the case and if one cannot
check beforehand because they won’t answer
the telephone or reply to letters — a common
occurrence — then an abortive trip may be
made.
Could you not assist by declining to publish
an advertisement if the goods are not certified
in stock at time of placement?
A. S. Goodenough,
North Harrow, Middx.
@ This is a serious problem which causes us
some anxiety. Because of the world shortage
of Schottky ICs, several manufacturers have
difficulty through no fault of their own. That,
of course, is no excuse for not responding to
enquiries.
We regard it as our responsibility to investi-
gate unreasonable delays in supply of goods
advertised in our pages, and if a company per-
sists we would have to consider refusing to
carry its advertising. To help readers in this
way, we have to be informed of specific
instances.
Here at last
INTEL has produced its long-awaited one-
megabit bubble memory, under the desig-
nation 7110. The principal plus is non-
volatility — you don’t lose contents of memory
when you switch off. Compactness also looks
good — 128KB on 16 sq. in. of board space
(4X4 in.), IMB on 90 sq. in. Error correction
is built in, too.
You need a separate controller and at
$2,000 for the prototype kit, the early prices
well not drive out the (much faster) MOS
memories we all know and love. Still, the
megabit bubble should provide more products
to stand alongside the only bubble-using sys-
tems in our business, the pioneering terminals
from Texas Instruments.
The megabit bubble has some other stories
behind it, one of which demonstrates Intel’s
insight. Noyce is a breakaway entrepreneur
(from Fairchild) and the megabit memory
maker, a subsidiary called Intel Magnetics, was
set up by Intel 18 months ago, when three
ambitious youngsters from the Hewlett-
Packard bubble memory development squad
looked for finance.
The TI 92Kb bubble memory — as used in
(continued on page 47)
45
ORCERER™
Now becomes a professional
word processor...as well!
The Sorcerer Computer is a completely assembled and tested
computer system ready to plug :n and use. The standard configuartion
includes 63 key typewriter-style keyboard and 16 key numeric pad,
dual cassette 1/0, with remote computer control at 300 and 1200
baud data rates, RS232 serial 1/0 for communication, parallel port
for direct Centronics printer attachment, Z80 processor, 4K ROM
Operating system, 8K Microsoft BASIC in separate plug-in Rom
PactM cartridge, composite video of 64 chars 30 lines, 128 upper/
tower case ASCII character set and a 128 user-defined graphic
symbols, up to 32K on-board RAM memory, operators manual,
NOW CONTACT YOUR LOCAL DEALER 7”
PRICES
8K Sorcerer
.. OR SEND COUPON 16K Sorcerer
32K Sorcerer
pia ag 630K Dual Disc Drive
INFORMATION 143K Single Disc Drive
$100 Expansion Unit
Line Printer
Video Display
Development Pack
Word Processing Pack
Technical Manual
Daisvwheel type printer
Word processing pack
Video/disc unit
16K Memory expansion
BASIC programming manual and cassette/video cables, connection
for $100 bus expansion unit.
The Word Processor Pac creates, edits, re-arranges and formats text.
Features include auto wraparound, dynamic cursor control, variable
line length, global search and replace, holding buffer for re-arrangement
of text, right justification, line width and line to line spacing, under-
lining or boldtacing, text merging and a macro-facility permitting
tasks such as form letter typing, multiple column printing or auto:
matic forms entry.
LANCASHIRE
051-2272535 MICRODIGITAL 25 Brunswick St.. Liverpool L2 BJ
WEST YORKSHIRE
0535 65094 BASIC COMPUTING Oakville, Oakworth Rd., Keighly
SHEFFIELD
0742-668767 E.S. MICROCOMPUTERS ? Berkley Precint, Ecclesall Rd.. S11 8PN
NORTH WALES
0248-52042 TRYFAN A/V SERVICES 3 Swifts Bldgs., High St., Bangor, Gwynedd
AVON
0272-292375 ELECTROPRINT 5 Kingsdown Parade, Bristol BS6 5UD
NORTH HANTS
0536-83922 H.B. COMPUTERS LTD. 22 Newland St., Kettering
LONDON & Counties
BERKSHIRE
0635-30505 NEWBEAR COMPUTING STORE 40 Bartholomew St.,
; Newbury RG14 5LL
KENT Z
01-300 0380 INFORMEX 6) Harland Avenue, Sidcup, DA15 7NY
SURREY
0276-34044 MICROBITS 34b London Ad., Blackwater, Camberley
0276-62506 T. & V.J. MICROCOMPUTERS 165 London Rd., Camberley
@ Circle No. 167
PRACTICAL COMPUTING September 1979
(continued from page 45)
the 763/765 printer terminals — will be joined
soon by a 25Kb unit from the company and it
reckons to join Intel in the megabit market
later this year. The probable standardisation in
components looks to be at 256Kb and 1Mb,
with Rockwell likely to have them along with
TI and Intel by the middle of next year.
IBM and Bell Labs are both reported to be
near the technology for 4Mb_ bubble
memories. Meanwhile, HP is probably the
most active of the rest of the bunch in this
field. The costs and problems of the bubble
memory business were exemplified by the
recent Univac decision to buy the components
rather than make them,: the chosen suppliers
are TI and Rockwell.
Univac, however, is going ahead with pro-
totype work in the more esoteric areas of bub-
ble memories, designs which will not appear
until 1982 or thereabouts, and which Univac
may not decide to manufacture even then.
In a speech at the Midcom Electronic Show
and Convention at Dallas, Texas, in December
1978, Pasquale Pistorio, vice-president of the
Motorola Semiconductor Division, made sev-
eral predictions about the semiconductor
industry which are worth noting:
@ The world market for semiconductors will
rise from $80 million in 1978 to $19 billion
in 1985.
@ The computer industry will be shaken up by
the forward integration of semiconductor
houses and backward integration of elec-
tronics equipment manufacturers.
@ Members of the oil club — corporations or
countries — will enter the electronics and
semiconductor business.
@A consolidation process will materialise,
with a small number of suppliers, with fewer
large broad-range companies and more pro-
duct or regional specialists.
Re-loading
ABOUT 18 months ago we decided to purchase
a computer with word processing capability
rather than a true word processor. In our
ignorance, what an inspired decision it turned
out to be. Not only has it revolutionised our
marketing and management strategy, it has
given us the incentive to read your excellent
magazine.
It occurred to me, while reading your Feed-
back column, that you may be able answer a
problem which we are experiencing with our
Ricoh printer. It is the speed with which we go
through carbon ribbons. We use about one-
and-a-half cassettes a day at a cost of £2.25
each. The cassette appears to be very simple
and refillable, however, but to date | have not
been able to find any supplier to re-load exist-
ing cassettes. Perhaps you can help?
Alan Bosworth,
Sage Consultants,
Fleet, Hampshire.
Zombies again
HERE are suggested modifications and
improvements to the Zombies game (June
issue) to allow it to run on the Pet.
The dimensions are changed to allow the
board to fill the Pet screen and also to make
use of the numeric keypad. To this end, the
data statement was changed, as were the
instructions at lines 730-750. The alterations
in lines 760-790 are to leave the instructions
on the screen until a key is pressed. 1 hope
these alterations will be of use to other Pet
users.
PRACTICAL COMPUTING Septernber 1979
150 Prinrst"
160 Dim B(12,20),Z(25,2),P(9),Q(9)
290 Print “*°:Z1=0
340 For N2= 11020
390 For N2=2to0l9
400 R=20°RND(TI)
420 lf R 17.90 then 480
540 = X=5+int(10°RND(1))
550 Y=3+int(5*RND(1))
760 hia
770 ? Tab(7y"$Press a key to start’
780 Get A$:1HAS$="" then 780
790 ite
940 For N2=1t020
Inpur* Your move’ A
deleted
Input “Another game’ A$
deleted
I] missed these lines out of order:
200 For N1=1 to9
230 Data —1,1,0-1.1,1,—1,0,0,0,1,0,-1,-1,0.-1,1,-1
730-2 "789"
740-2" 4X6"
750, 9123"
If the 5 key is pressed, the X stays still but
the Zombies move. The ? is short for PRINT.
The + is for clear screen. The ¢ is reverse on.
1 hope these alterations are of interest.
Colin Spencer,
London, NW7.
Superboard aids.
FOLLOWING the Superboard Review (June
issue), may | just clear up a few points?
We fit a free SV modulator to all our boards
and thus maintain the single supply para-
meters.
The magnitude of numbers handled by the
Basic is up to +10°*, but remember it isa 6%
digit Basic so it sounds off at the 6th digit. It is
easy, however, by programming to recover
more information and produce results accurate
to | part in 10° or no errors up to 999,999 -99.
Although there are few commands in the
machine code monitor, if you wish to work in
machine code there are available on cassettes
an extremely versatile Extended Monitor and
also an Assembler/Editor. A disassembler is
also included.
None of our customers has as far as I know,
had to reduce the termina! width (characters
per line) to fewer than the normal 24. If you
have to do so and require to SAVE the prog-
rams on cassette, the following will allow you
to do so without error:
POKE 15.72
SAVE
LIST
return.
feturn.
return.
This will also re-set your terminal width to
24; but you can re-set it to 23 by POKE 15,
23. No alterations are necessary on playback.
We also provide a listing of a machine code
program which enables machine code prog-
rams to be dumped to tape in auto load format
and/or displays blocks of memory on screen. In
addition, we have a program which moves
blocks of memory, while in Basic we have a
re-number program, not yet converted to
machine code.
Lastly, while you found that the Superboard
performance in benchmark tests was very fast,
a simple modification will run the processor at
2MHz instead of 1MHz, thus doubling the
speed to make it almost the fastest home com-
puter on the market — my demonstration
Superboard runs happily at 2MHz with the
standard 5SOns memories, although | had to
“select” them.
P. S. Fawthrop,
Calderbrook Technical Services,
Littleborough, Lancs.
a 8S
Rotating view
YOU SEEM to have misunderstood Paul |
Benham’s question — Astronomy, (Feedback,
June). He wonders if home computers can show
us the rotating perspectives and cross-section
selections drawn as they are in computers
shown on television.
His interests could be assisted by a rotating -
view of a sun/comet ellipse, as if in 3D. The
answer is “no”, since home computers pro-
duce their characters on the VDU as a dot
formation in a definite square, which is large in
area.
To obtain a line as an ellipse or circle, access
is required to the line and frame scan for the |
cathode ray tube so that x and y waveform
signals may be applied, and Lissajous figures
drawn. The size and angles of the figures could
be computer-controlled, a new device
designed, and a program written.
With the Tl 59 programmable calculator it
would be truer to say that if it can almost be
done on a personal computer it can certainly
be done on a T! 59, but without the great dis-
play, graphics being limited to the PC 100
printer.
With the 58 or 59, Fourier transforms and
functions are a simple programming proce-
dure. Inputs are by “label” keys, complex
numbers are handled with explicit ease, and
the use of definite addresses for memory
makes programming unlaboured. The ability
to operate within a choice of degrees, radians
or gradians makes life easy.
1 have progressed from the Sinclair prog-
rammables, through the Tl 58 to the Commo-
dore Pet, which is a great delight, but I must
admit that | was at first appalled by the care-
less mathematics of the home computer, com-
pared to the delightful accuracy of the TI 58.
Pet says TAN 45= 999999999: TI 58 says 1.
Rex Tingey,
Holywood,
Co. Down.
Exchange
CHRIS CAIN of the Engineering Wing, RAF
West Drayton, Middlesex, is interested in
starting a TRS-80 software exchange. If you
would like-to help or contribute to it, write to
him there, with a SAE, please.
Assurance
MR WITHNALL writes (July issue) lamenting the
changes incorporated in the new ROMs of
32K and 16K Pets. He states specifically that
Microchess 2:0 does not work with the new
ROMs.
I would like to re-assure him and other Pet
users that versions of all 160 Petsoft programs
have been amended to run with the new
ROMs. Withnall should be able to find a copy
of a revised Microchess at his local computer
store.
We will be happy to advise if anyone is
experiencing difficulty running our programs
on the new Pets, | think, however, that most
users will eventually wish to upgrade to the
new ROMs, which offer a number of sig-
nificant advantages over the original set.
Julian Allason
Petsoft,
Newbury, Berkshire.
47
TV rental firms ready for
computer market
Britain's TV rental companies
are about to enter the personal
computer market. The com-
punies have for some time
been offering TV sets capable
of receiving Ceefax and Oracle
— the BBC and ITV teletext
services,
Since March, when the ser-
vice was launched, they have
also been offering sets capable
of interfacing to the Post
Office Prestel service, which
allows the telephone user to
access information from a
large computer database for
display on a TV set.
It is still very limited, and is
available at the moment only
in the London area.
The rental companies and
the British TV manufacturers
expect that more than 16,000
Prestel sets will have been
delivered by the end of this
year, with production running
at about 1,000 sets a week.
Since a TV set capable of
receiving Prestel will cost
about £1,000, the rental com-
panies expect that the majority
of users initially will opt to
rent rather than purchase.
Rental is expected to be about
£24 a month.
Over the next two years TV
rental companies expect to
have entered the personal
computer market with units
Microframe.
which can be linked into the
home TV and perhaps can also
be connected to the Prestel
service. The companies expect
to rent systems not only for the
home, personal and edu-
cational markets but also for
business, where rapidly-
changing technologies can be
tested by a potential user on a
weekly rental basis before buy-
ing or entering into longer-
term leasing.
Big names
Since many of the TV rental
companies are owned by com-
panies which also manufacture
TV sets, it could be that we
will see a range of all-British
personal computer systems on
the market within the next
year to 18 months.
That speculation is to some
extent reinforced by fairly per-
sistent rumours that both GEC
and Thorn are developing per-
sonal computer systems,
though neither company has
made any announcements.
Philips, however, has
announced that it is working
on integrating its new range of
viewdata sets with some of its
existing computer products, in
particular word processing sys-
tems.
Such a system could consist
of a viewdata terminal and a
Philips 2650-based personal
computer, together with a
modified laser video disc for
mass storage; this would prob-
ably have a capacity of about
1,000Mbytes.
This system might incor-
porate a facility for using tele-
software, a method of trans-
mitting programs as viewdata
frames. This is being
researched by at least one of
the major ITV companies, in
conjunction with a software
house. A system of that kind
might cost less than £1,500
and be on the market within
the next two years.
Investment in the next three
years by some of Britain’s big
TV companies is expected to
exceed £200 million. Q
Compiler
for Z-80
RESEARCH MACHINES has pro-
duced an Algol compiler for
Z-80 systems with CP/M, such
as the Research Machines
380-Z. The Algo! will run as
little as 21K and one mini-
floppy; it implements most of
the features of Algol 60, the
main exceptions in the current
release being multiple assign-
ments and own variables.
Added features include the
byte arrays, logical operators,
string handling, and interrupt
handling — and graphics with
the 380-Z.
Other attributes of the com-
piler noted by RML are ‘‘ease
of use, speed, economic use of
memory, and excellent I/O
and file handling’. Benchmark
tests are available from
Research Machines.
Stocktaking from a
briefcase
STOCKTAAKING Can have a new
look with an all-in-one compu-
ter in a briefcase developed
jointly by Data Logic and
Allied Breweries.
Launched at the Microcom-
puter Show, the Microframe |
is based on the Intel 8080,
weighs 21lb., and can be used
‘‘by anybody who moves
around” in their jobs.
48
It is acomplete system with
4in. video display, keyboard,
floppy disc drive and thermal
printer, as well as applications
software. Full-size display,
keyboard, printer and an extra
drive can be attached if neces-
sary. The machine has 16K
RAM, expandable to 32K.
Allied Breweries controls
more than 2,000 public houses
throughout Britain and
specified the applications
software, which is written in
PL/M. The machine will be
used by the 120 stocktakers of
the brewery, who visit the
managed pubs to monitor the
sale of beer, wines, spirits and
tobacco.
It means that a good deal of
paperwork will be eliminated,
stocktaking results will be
available much quicker, and it
will be ‘ta great assistance in
overcoming the problem of
mis-stocktaking’’, says
Richard Havery of Allied
Breweries.
Data Logic is looking at
other applications for the Mic-
roframe, such as order proces-
sing, site management and
point-of-sale. A typical cost
per unit of the machine will be
around £3,000 for bulk orders.
It is expected to be available
for the commercial market at
the end of the year. D
PRACTICAL COMPUTING September 1979
U.S.-Japan link for
hand-held unit
THE first hand-held personal
computer has been introduced
in a joint venture between
Matsushita Electric of Japan
and Friends/Amis of the U.S.
The project ‘“‘will give birth to
an entirely-new field of con-
sumer electronics”, according
to a spokesman for the two
companies.
The key to the system is
Industry
growth
IT IS estimated that in 1978
some 250,000 personal com-
puters were sold, mainly in the
U.S. but with significant prop-
ortions in Europe and Japan,
the total market value being
about £175 million.
The industry is expected to
grow at a phenomenal rate and
sales for the first four months
of this year show that esti-
mated worldwide sales of
500,000 systems, valued at
more than £300 million, is not
over-optimistic.
If growth rates are main-
tained, there could be a world
market for personal computers
worth more than £3,000 mil-
lion by the mid-1980s, despite
the fact that unit prices will
continue to fall.
If the trend is correct and
there are, of course, numerous
factors which could restrict
growth, the size of the market
in volume terms is enormous,
and we could possibly see one
in every two households own-
ing or renting a personal com-
puter.
AMI memory, which holds
twice the amount of data of
conventional systems in tiny,
interchangeable capsules.
Through pre-programmed and
self-programmable memory
capsules, people will be able to
carry information on any area
of science, business, language,
education or the arts in their
pockets.
Matsushita Electric and
Friends/Amis will develop the
hardware and software jointly.
The former will manufacture
and sell the product under its
own label, as well as its private
brand names — Panasonic,
Technics and National. It will
grant sub-licences to other
manufacturers and both com-
panies will develop new appli-
cations for the system by
integrating their technology
and software.
Translator
Friends/Amis is a Califor-
nian-based microcomputer
software systems company
which developed the system.
It introduced the new tech-
nology earlier this year with
a language translator.
The new system will be used
in applications such as learning
systems, a new generation of
portable computers for home
or business use, electronic dic-
tation equipment, games, and
an unlimited range of infor-
mation systems, from first aid
to recipes.
Export sales are planned for
next year. A price has not
been decided.
Apex keyboard.
Micro keyboard
APEX MICROSYSTEMS has
developed a _ miniature
alphanumeric keyboard suited
particularly to small micro-
computers.
Designated the MKB.01, it
measures 165 X 93 X 14mm
and it will be useful for appli-
cations where size is impor-
tant, such as portable or
mobile data entry systems, or
as an alternative to conven-
tional keyboards in small sys-
tems.
lt may offer a satisfactory
alternative to the 8K Pet
keyboard, which is difficult to
use.
It is an 8-bit ASCII tri-
mode keyboard, in ASR33
tormat, and uses MOS tech-
nology. The unit uses high-
reliability tactile response
keyswitches with 12:5mm
spaced centres. All outputs are
DTL/TTL/MOS compatible,
Screen problem for TI 99/4
TEXAS INSTRUMENTS has
launched its personal compu-
ter amid a row with the U.S.
Federal Communications
Commission which will not
allow the semiconductor giant
to sell the machine in the
States without a TV screen.
The long-awaited Tl 99/4
was to cost around $300 to
$500 until the company was
forced to change its plans as
the FCC prevented it selling
the computer without a TV
screen — because’ the design
required a radio frequency
generator to enable it. to be
connected to an ordinary TV.
The machine is expected to
be available in the U.K. before
the end of the year and users
will need a separate monitor,
unless they have a screen mod-
itied to receive PTSC input. It
is hoped that later the 99/4 will
be fitted with PAL circuitry to
enable users to plug it into
ordinary U.K. sets.
The European version of
the 99/4 consists of a console
with 16K RAM = (non-
PRACTICAL COMPUTING September 1979
expandable) sound generator,
full colour graphics and
extended Basic. It uses plug-in
modules, much like the Sor-
cerer, which are all self-
contained programs and make
for much easier use.
Modules for the system will
include home financial deci-
sions, physical fitness, chess,
educated eating and pre-
school learning. Each module
will range in price from around
£15 to £45.
Accessories will include a
so the keyboard can be inter-
faced directly to most elec-
tronic systems.
There are two uncommitted
switches brought out to the
connector to enable functions
such as repeat and shift-lock to
be implemented. It also pro-
vides a two-key rollover to
ensure the minimum of opera- :
tional errors.
A choice of eight key col-
ours is available and, for
stand-alone applications, a
case and AC and DC power
supply interfaces and DC
packs. You can implement
specialist codes such as Selec-
tric by changing the ROM.
The MKB.01 is available at
a one-otf price of £55 plus 80p
post and packing, plus VAT. lf
you order more than four, it
will work out slightly cheaper.
Apex can be contacted on
(0443) 225578.
multi-position joystick for
games, a printer, disc memory,
RS232 interface and a speech
synthesiser. This is designed
on the same basis as the suc-
cessful Tl Speak & Spell learn-
ing aid and has a built-in voc-
abulary of 200 words.
It can be used by the home
programmer to produce
spoken messages and results in
his programs. Future com-
mand modules will also use 2c.
The Tl 99/4 will sell in the
U.K. for around £700, includ-
ing VAT.
49
Biproc kit with choice
of two processors
A NEW kit for ‘‘those
enthusiasts who are willing to
use a soldering iron and wish
to write programs at assembly
level language’’ has been
developed by BL Mic-
roelectronics.
This home microcomputer
kit offers the choice of two
processors — an 8-bit Z-80 or
a 16-bit TMS9980, without
the extra expense of separate
RAMs, control and I/O inter-
faces. Either processor can be
inserted in separate sockets,
and each has a monitor and
line-by-line micro-assembler
in a 2K TMS2716 EPROM
package.
The BIPROC board, as it is
called, is a double-
double-Eurocard size 1/16 in.
thick, through-hole plated,
and is solder-resistant-painted
on both sides. It has been
laid-out in two sections. Sec-
tion B contains the TV scan-
ning circuit and keyboard
interface which can be cut off
in dedicated tasks. Section A
may be inserted in a double-
Eurocard slot.
The board is fully socketed
in three kits. The processor is
either a Z-80 or a TMS9980.
There is 1K of static RAM —
about four percent of memory
space is reserved for the
monitor — and 4K ROM.
Interfaces include memory
mapped with 1K x 6 static
Sorcerer
group
ANOTHER Sorcerer users’
group, Exidy Sorcerer Users’
Group (U.K.), is a British off-
shoot of the U.S. user group.
It aims at communication
between owners, to offer soft-
ware tips and to keep you
informed of the latest software
and hardware developments.
There will be a monthly news-
letter, based on the informa-
tion of the U.S. group and the
fee will be £5 per annum. The
only stipulation for joining is
that you must own a Sorcerer.
Contact is Andy Marshall,
Micro44, 44 Arthurs Bridge
Road, Woking, GU21 4NT.
Tel: (04862) 66084/72650. J]
50
RAM TV scanning circuit for
generating 16 lines of 64
characters each on a domestic
TV set, cassette recorder, key-
board, fully-buffered data and
address bus, RS232 interface
for terminals and memory-
mapped parallel I/O lines.
Software includes memory
map, prominent cursor display
and six commands which can
be invoked via the keyboard.
Documentation for the system
is in the form of a users’ man-
ual with circuit diagram, parts
Biproc 8/16-bit mini
lists, assembly and operating
instructions. Some _ prog-
ramming examples are
included.
The Biproc kit 1, with Z-80
only, costs £194; kit 2, with
TMS9980 only, costs £199;
and kit 3, with both pro-
cessors, costs £225. Two X 40-
way DIL multiple insertion
sockets are £7 extra. Contact
BL Microelectronics, | Willow
Way, Loudwater, Bucks
(0454) 26670, for more
details.
SS re ee ee
New Apple
software
APPLE II and ITT 2020 users
will be pleased to hear that
Computech has launched a
new range of low-cost business
software for those machines.
Called Computaccount, the
series comprises sales, pur-
chase and general ledger, pay-
roll and stock control. The
packages are designed to run
on 32K RAM, one or more
disc drives, printer with serial
or parallel interface, domestic
TV or video monitor and
Applesoft in ROM.
A version to run with
Applesoft in RAM, needing
48K, is also available. A typ-
ical cost of each package is
£295 and support and
enhancements will be avail-
able to existing users at dis-
count prices.
“Particular advantages’,
says Computech, “arising from
this approach mean that the
user can define his own para-
meters, on-demand data dis-
play and a random file struc-
ture which means that the fast
response of the system is not
degraded as the volume of
data increases.”
The packages have com-
prehensive manuals dealing
with everything from the ele-
ments of double-entry book-
keeping through to notes for
advanced users on system
expansion. Computaccount
packages are available from
ITT and Apple dealers. 9
Bubbling: at Intel Fair
INTEL FAIR again provided a
platform for several products,
including bubble memory,
CIS-Cobol and Multi-ICE.
The world’s first one-
megabit bubble memory was
there, with its entourage of
supporting chips attracting
the most attention at the
exhibition. It is called the 7110
and is a product of Intel
Magnetics, the company set up
by Intel to accommodate three
personnel from Hewlett-
Packard’s bubble memory
development team. They had
the knowhow and Intel had
the money to produce the pro-
duct.
Intel's Vendor Supplied
Products. CIS-Cobol, a Micro-
Focus production, will run on
the 8080/8085 processors and
is a direct descendant of the
well-liked version from the
software house. It runs under
the ISIS operating system on
an 8080/8085 processor con-
figured with 64KB memory
and single-density floppy
discs.
It features relative and
indexed file handling, facilities
for inter-program com-
munication and library fea-
tures. For interactive oper-
ation through a VDU, there
are facilities for field for-
matting, protected areas and
dynamic file-handling which
allows file names to be
assigned at run-time.
Multi-ICE, a software pac-
kage for debugging dual pro-
PRACTICAL COMPUTING September 1979
cessor configurations, was also
given an airing. It is based on
ICE — In-circuit Emulator —
which helps to alleviate the
problem of tracking where
exactly an error has occurred
on a processor, but allows two
such emulator modules to run
on a single Intellec system
simultaneously.
Intel sees it being used in
the first place on systems using
two 8085A processors, or an
8085A and a single-chip pro-
cessor from the 8049 family.
Intel Fair attracted some
800 visitors, and is turning into
one of the company’s most
important annual events. As
usual it was well supported by
seminars and a_ healthy
number of exhibits. O
@#e@eeoeeeee@eeseee808 8
i
) >
be &
Am ae
—
Sa
BLACK BOX MICROCOMPUTER
@ Circle No. 168
PRACTICAL COMPUTING. September 1979 51
Keen Computers t ? ‘ve ur
the Future coith the vip
\*
y
f
Apple 11 16K 830.00
Additional 16K Ram 90.00
Applesoft Rom 110.00
RS232 Card 110.00
Colour Card 90.00
Disk Drive and Controller 425.00
Disk Drive W/Ot Controller 375.00
Speech Lab 140.00
Apple Clock 165.00
Printers from 350.00
Prices subject to change without
notice.
@ Circie No. 169
52
rN |
~?
?
7 :
S07, \
sae 7
>, =
hy ea ity
So - =, 7%,“ Pe ff
tan ~ >. %. & . 3 5
a a 4 4 = . =
—_ @ ix ~~ e
& ~
a 2 ~
Software Packages are available
for most business applications.
A few are:—
Word Processor, Information
Retrieval, incomplete Records
Accounting, Sales Ledger, Order
Entry Invoicing, Management
Information, and a variety of
Statistical Packages, Games,
and others.
Keen Computers
SbThe Poultry
Nottingham
Tel: 060) 503254
Telex 37297
PRACTICAL COMPUTING September 1979
THE POWERHOUSE 2 is a compact, all-in-one microcomputer and it reaches the
market in various forms, but all housed in the same cabinet. It probably will draw
comparisons with computers like the Commodore Pet, Tandy TRS-80, Apple and
the rest.
THE VERSION delivered for review, which
was a pre-production model, has 32K
bytes of RAM, 14K of Basic in EPROM,
a mini-cassette drive and disc operating
system (DOS) in EPROM.
Common to the range is a Sin. CRT
VDU screen, a 58-key alphanumeric
keyboard in the normal typewriter layout
for most keys, Z-80 cpu and basic operat-
ing system (BOS) or monitor in EPROM.
All is packaged in a neat, compact hous-
ing which stands on an area about the size
of this magazine opened out, and around
only 7in. high.
Setting-up
Because the Powerhouse 2 is a com-
plete packaged system, it needs only to be
plugged into the mains to be powered-up.
In use
On connecting the mains lead, the
computer is powered-up by the mains
on/off switch at the back of the unit. Our
review model had an intermittent power
supply problem which manifested itself
on initial power-on — it would power-off
.| momentarily and collapse the screen dis-
play.
There was not enough time to trace the
fault, but as it happened only on
powering-on and eventually it would set-
tle, it did not affect the working of the
computer once it has stabilised itself.
Because of this power problem, how-
ever, I could not determine whether the
Powerhouse 2 does a power-on re-set as
it sometimes is ready in monitor, and
sometimes is not. Nevertheless, it is a
simple matter to press the Re-set key —
well, not so simple, it is actually Shift
re-set. Although this seems a little awk-
ward it may be intentional. Since the
Re-set key is the top left-hand corner key
on the keyboard it would be very easy to
mis-hit it and possibly lose valuable work,
hence, perhaps, the two-key re-set.
The keyboard has 58 keys of which the
top row are special function keys and the
next four rows have the alphanumerics in
the normal typewriter QWERTY layout.
Some of the punctuation marks are found
in different places and the two shift keys
are in a row on either side of the space
bar.
The “return” or “enter” key is where
the right-hand shift key is normally
found; irritatingly, it is also of the same
size as the other keys, so it is not con-
venient to hit.
PRACTICAL COMPUTING September 1979
All these unconventional positions are
minor irritations, to which one can accus-
tom, but why have a conventional key-
board layout which is only very slightly
unconventional and shows no obvious
ergonomic advantages over the standard
form?
The keys have a low profile and
although they can be hit positively, they
lack some feel. Sometimes, on repeating
a character quickly, the key does not
register the second hit. Having said that,
it is still workable and nowhere as bad as,
say, the original Pet keyboard.
The CRT screen is of high quality, dis-
playing 16 lines of 64 characters to the
row. It is fixed to the keyboard and at the
by Vincent Tseng
working distance it appeared to be about
the correct size, clarity and contrast
despite the fact that a Sin. diagonal screen
sounds small. The brightness can be
adjusted by a control at the back of the
unit.
The character set displayed was small,
64 characters with upper-case only, from
ASC2 Z6 to 5F hex inclusive. There are
also flashing versions of the same set of
characters defined by AQ to FF hex anda
clear screen control character.
Built-in with the unit was a mini-
cassette drive for mass storage. This is not
the Philips audio mini-cassette — as for
dictating machines — but a digital cas-
sette drive using a certified digital cas- ,
sette. All the cassette controls are inter- |
nal so there are no play, record or re-
wind buttons.
Monitor
The firmware monitor is in 3K of
EPROM which Powerhouse calls BOS or
basic operating system. It is to this that
the computer is initialised when the
(shift) re-set button is pressed. The
prompt symbol is an asterisk * followed
by the cursor which shows the current
position on the screen by an underline.
The usual machine code monitor com-
mands are found, such as memory display
““D”’, change memory location ‘I’, dis-
play registers ‘**R”’, jump to location and
start execution ‘“‘J’’. There are also some
useful commands such as fill memory
“F’, between two addresses with any
user-defined byte pattern and a RAM
confidence test between limits of address
by “Q”.
There are no break points or even hints
on how to set them up —e.g., using one of
the restraint instructions; also the
monitor lacks the single-step facility. This
is very unsatisfactory, as the user does not
have any convenient facilities to test and
debug program.
(continued on next page)
53
rue
Compact for business
| (Continued from previous page)
Another annoying feature is that to
enter or terminate a command line, the
monitor uses the full-stop key which is
situated next to the enter key. Since the
other “‘software systems” on the Pow-
ethouse 2 all use the enter key for ter-
mination, it is all too easy to lapse and use
this key for the monitor as well; then the
monitor shows ‘error by a flashing ““<”
sign and there is no recovery of that last
command line.
The user has to re-enter the whole line
again, this time remembering to use the
full-stop key. So why have the two
methods of working, as again there is no
advantage in using the full stop?
Basic
When the DOS key on the top row is
hit while the system is in the monitor
(BOS) a jump into Basic is made. The
Basic is the North Star version 6 in 14K
of EPROM and has a useful set of
instructions, including many string-
handling functions. The functions avail-
able are comparable to those in the 8K
microsoft Basic, as on the Superboard 2.
The range and precision calculation is,
however, higher, since the Powerhouse 2
Basic can go into exponential notation —
like scientific calculators.
It is good that there is a command to°
edit a line defined by line number. The
editing commands are primitive, using
control keys, but useful. It certainly is far
better than not having an edit facility.
The now “standard” (by default) eight
benchmark programs show that this vers-
ion of Basic is not particularly fast, but is
in the same region as the Pet and Apple
Applesoft Extended Basic.
It is very peculiar that, though the
Basic is in EPROM, when it is called-up
the whole interpreter is loaded into RAM
and occupies 15K worth of RAM area
(from 2000 to 5 BFF Hex). Therefore, the
32K machine becomes an 18K machine
— what a waste, when the Basic interpre-
ter is already in memory.
Having written a program and wishing
to save it, one uses the Basic “SAVE”
command but the system returns an error
as the named file has not yet been
Distributor
Powerhouse Microprocessors Ltd
5-7 Alexander Road,
Hemel Hempstead,
Herts HP2 5BS 0442 48422
defined, which leads conveniently into
the Disk Operating System.
The Disc Operating System, like the
Basic, is by North Star. The DOS allows:
the creation and storage of files by name
and type on floppy discs or cassette tape,
but the method of operation is somewhat
primitive. For instance, to save a file from
Basic, the user needs to drop into DOS
first, and call up the “CR” for create
command and specify the length of the
file in numbers of 256-byte blocks — how
many people know the number of bytes
needed to store a Basic program?
Then the file type has to be specified by
using “TY” — “@” for default pure
machine code/data; ‘‘1”’ for machine code
with a jump start address; ““Z’” for Basic
programs and ‘‘3’’ for Basic data.
There are good points, too, like ““L1*
for listing-out all the files created so far;
some files could have been created but
not filled, and there are no indications of
the file being empty.
Also there is a “CO” for compact, an
instruction which, as the name implies,
compacts the files stored, i.e. tidies them
up, to create more spare storage space;
this is especially useful when files have
been deleted and holes have been left
behind.
Those readers who have been paying
attention will have noticed that floppy
discs were not included with the review
system. Does this mean the reviewer
relied on the manuals for all this? The
answer is no. This is a really excellent
point about the Powerhouse 2 — the disc
operating system is one and the same as
the cassette operating system.
The two are identical in all operational
commands. Naturally, only the access
speeds are different. This means a user
can upgrade from cassettes to floppies
ROBOX LTD
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Dealer enquiries welcome
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KIRKINTILLOCH: 84 TOWNHEAD 041-776 4388/1253
GLASGOW: ANDERSON SHOPPING CENTRE
@ Circle No. 170
PRACTICAL COMPUTING September 1979
and still work the same way. Or he can
use the system away from his base on cas-
settes instead of floppies. I do not, how-
ever, know if a system can have both
floppies and cassettes working together
so that files can be transferred from one
to another. It would be a pity if it did not,
because some of the advantages cited
would not apply.
This, however, could be a simple mat-
ter of re-numbering the drives, so that,
say, one of the “floppy drives’ is the
built-in cassette.
Other points
Basic and DOS use a different stack
area to the monitor (BOS). This means
that different stack pointers are initialised
which can be dangerous to your software
when returning into the monitor via a
jump. The machine program can have
unpredictable results, since the stack
pointer now points at a different area.
This is not very satisfactory. Also, since
Basic dumps itself into RAM area 2000
— 5BFF Hex and as the DOS is called via
Basic it is hard luck if you put in a 14K
program in machine code starting at
Z000 Hex and want to store it on cas-
sette. The first really safe free address is
5C0@ Hex and the user RAM in our ver-
sion stretched to 9BFF Hex.
A few words about electrical safety.
The test mode! was a pre-production ver-
sion but it had a few potentially-
dangerous faults, such as a wide ven-
tilation grill on top of the unit with no
protective mesh, so that fairly large
objects could be dropped into the high-
voltage spots. The plastic case top cover
is fixed only by a lip and notch at the
front and two self-tapping screws at the
back which go straight into the bottom
plastic base.
This arrangement does not look par-
ticularly robust. Once the cover is
removed, the mains cable leading to both
the on/off switch and the fuse is very
exposed. To be fair to the company, these
problems have already been noted and
the faults should be corrected in the pro-
duction versions.
The keyboard is not encased. What
appears to be a case board is the PCB on
which the keys are mounted, painted
white, and again fixed in by self-tapping
screws to the case.
Documentation
As this was a pre-production model it
had pre-production documentation. The
manual (pre-proof read) deals heavily
with the hardware description but all the
operating instructions are described, if
somewhat briefly. The chapters on the
different parts, however, appear to be
derived from different sources. A list of
usable subroutines in the firmware is
given with the starting address. This is
useful, but some programming examples
would have been more useful. The dis-
tributor says that ‘‘the appearance, lay-
out and content of the final version will
be much improved’.
Conclusions
@ The major attraction of this system is
is compact and neat packaging. The casing
could be made more robust.
@ Further external expansion is via a
parallel interface but not to standard bus.
There is an RS232 (or V24) serial inter-
face, so that the Powerhouse could be
used as an intelligent terminal.
@ There are no particularly outstanding
features, except perhaps the use of the
same operations for both disc and cas-
sette. There are some shortcomings, of
which the worst is the Basic dumping
itself into 15K of RAM — but what sys-
tem is perfect?
® Value for money cannot be judged,
because no price has been fixed, but the
use of certified digital cassettes cannot be
cheap. Although ‘it is claimed not to be
aimed at the amateur market, com-
parisons will be made and so competition
from those quarters cannot be ignored. [J
Practical Computing evaluation
i Yes/No +2 3 4s Yes/No (72); 3 1475
NA N/A
Ease of construction (where NA Lower power consumption ®
applicable)
Assembly language M/C code
Quality of documentation e .
Basic language e
Can handle 32K of memo v
v Other languages N
Quality of video monitor e a a ’
(consider resolution and Compatibility with other e
screen size) Eyeolbe
SS-S0 Bus N Appearance tC
$-100 Bus N Portability ®
Sockets for chips No. of software applications e
packages available
| Numeric, caiculator-type N
pad on keyboard Hobby use @
Large amount of removable N Business use e
memory, randomly accessible Siteeaciowal use e
Cassette tape recorder N. pA ,
capability: Own Ability to add printer{s) Y
Buileinredorder Ability to add discs Y
Floppy disc capability Y ane sachie eewer" ”
manufacturers’ plug-in memory
Communications capability
(can talk to other computers) {
3 F Ratings
aa nreroe rae hs 1 = poor; 2 = fair; 3 average; 4 = good; 5 = excellent. N/A =
Ease of expansion @ not applicable.
PRACTICAL COMPUTING September 1979
55
AS THE COST of chips continues to fall, the
number of low-cost microcomputers
available appears to rise in inverse pro-
portion, and one recent -addition to the
market is the Acorn microcomputer.
it is a two-board unpackaged system
from a company called, somewhat confus-
ingly, Acorn Computer, for £81 assem-
bled and £70 in kit form. The Acorn also
requires a separate 5V power supply
before it will blink into life, as do many
other low-cost computers.
In common with Apple, Pet, Kim and
Aim-65 the Acorn uses the 6502 proces-
sor from MOS Technology. It is capable
of addressing up to 65K of memory if all
address lines are implemented on the
processor board.
The Acorn, in fact, has just over 1K of
RAM on the processor board. Additional
RAM can be added using an expander
board, together with one or more 8K
memory boards when they become avail-
abie.
The two Acorn circuit boards are
| mounted one above the other and are
connected by a 20-way cable. The lower
board, which is also available separately
Continuing our reviews
of single-board com-
puters, John Bennett
looks at the neatly-made
Acorn.
as an industrial controller board, contains
| the CPU, 1K RAM, a 16-way RAM I/O
56
chip used by the keyboard, the monitor
RAMs and address decoding circuitry.
Sockets for an additional RAM 1/O and
2K of EPROM are also included.
Three switches may be added to the
board to generate RESET, Non Mask-
able Interrupt (NMI), and Interrupt
Requests (IRQ) signals, or additional
devices may be daisy-chained on to the
board when more than one device which
generates interrupts — or re-sets — is to |
be connected.
The re-set switch is duplicated on the
upper board since the switches are hidden
when the boards are mounted together.
The upper board also contains a 25-key
Hex keyboard, an eight-digit display, and
a CUTS cassette interface.
Our review system was delivered
already assembled so it is not possible to
comment on ease of assembly. All chips
are socketed, however, and their posi-
tions are marked clearly on both boards,
so there should be few problems with
chips being orientated incorrectly. Addi-
tionally, the circuit boards are coated in
solder mask to prevent solder splashes
from sticking to the tracks.
Assembly instructions are detailed in a
separate manual, which contains a parts
identification list and some useful hints
on soldering technique, as well as instruc-
tions on assembly. A simple power-
supply circuit is included for those. who
From little Acorns
The little Acorn computer is one of the neatest we have seen. It is
arranged on two bolt-together boards. Notice the calculator-style dis-
play and the well-laid-out keyboard. The object in the background was
built by Mother Nature Systems.
would like to build their own, together
with details on the methods of configur-
ing the available memory.
Our manual was rather flimsy, consist-
ing of photocopied pages stapled
together. Presumably a printed version
similar to the programming manual is in
preparation. As the cost of an assembled
Acorn is £10 more than the kit it may
well be simpler, unless of course you are
an electronics buff, to buy a ready-built
Acorn, and avoid those anxious moments
before first switch-on.
The Acorn came to life as soon as
power was applied, displaying eight dots
on its LED display which signifies that all
is well and a monitor command may be
entered. The keyboard has 16 Hex keys
— 0-9, A-F — and 9 command keys
labelled RST,M,G,R,P,t JL,S.
The Re-set key initialises the processor
to a known state and is often used to
recover contro] from a program which is
in a loop. The memory key M allows the
contents of different memory locations to
be examined and altered, while the f and
sys allow the next or previous addres-
ses to be examined without entering a
physical address.
Entering M,0,0,3,0,k,A,D,f — where
k is any command key — causes the con-
tents of 9030 to be displayed and then
PRACTICAL COMPUTING September 1979
replaced by AD. The k and f terminate
the two phases of the memory command.
The first phase allows the contents of a
location to be examined and pressing f or
J allows the next or previous location to
be accessed.
Entering a hex character moves the
value into the least significant digit of the
current location, the contents of which
becomes the most significant digit. This is
repeated until a command key is pressed.
The command is then executed as in the
example where the contents 0031 would
be displayed.
The load (L) and store (S) keys are
used by the integral cassette interface.
They permit the contents of contiguous
sections of memory to be saved to and
re-loaded from tape by writing the start
and end addresses to tape prior to the
contents of the memory block.
Breakpoint
A breakpoint may be inserted into a
the P key so that the program may be
debugged by examining registers and
memory locations. Pressing the R key
re-Starts the program.
Programs are executed by using the
| GO (G) key, entering the start address,
| and pressing a further command key.
Each command causes a different letter
to appear in the mode portion of the dis-
Anadex DP-8000
available.
PRACTICAL COMPUTING September 1979
program at a specific location by pressing |
play so that it is possible to tell which
command is in use. The M key, for
instance, causes an A (for memory Alter)
to be displayed.
A 01030 . AD
display format
Mode data
An added refinement of the Memory
and Go commands is that they remember
the last address used, so that it is not
necessary to keep re-entering the start
address of a program, or a specific mem-
ory address. This is possible because the
monitor reserves locations in memory for
the addresses. The other locations used
by the monitor, together with a monitor
listing, are detailed in the system manual.
That contains a wealth of information
about the system and its use, including a
helpful glossary of terms encountered in
the manual. As with many low-cost man-
uals, it suffers from a lack of editing. In
fact, it probably attempts too much in the
space available, which results in some
portions being very readable while others
appear to gloss over the finer points. The
hardware sections are in parts particu-
larly vague. Perhaps purchasers are
expected to be interested in software or
hardware, but not both.
The manual is divided into two parts.
Part one deals with use of the system,
while part two contains a selection of use-
address
minute).
RE SS ye ee
ful programs, including games and utility
routines. A monitor listing is included in
part one. The monitor, incidentally,
| includes several subroutines which may
be used in other programs — for instance
to put characters on to the display.
Part one also contains chapters on the
binary number system, using tapes and
breakpoints, the Acorn hardware, and
| three chapters on the use of the system
and its commands, and the internal oper-
ations of the 6502. Those three chapters
provide a clear indication of how to prog-
ram the system by means of an example
which increases in complexity as the
chapters develop.
Resemblance
One possible improvement to the
manual would be to devote it entirely to
software and to develop the construction
documents into a hardware manual.
This would in all likelihood push up
the cost of what is at present a
competitively-priced and well-designed,
expandable system.
The Acorn manual bears a passing
resemblance in its general layout to that
from another Cambridge-based systems
supplier, Science of Cambridge, which
sells the Mk 14 kit. The Acorn, though, is
slightly more upmarket, offering greater
expansion capability, an integral cassette
| interface,and:more monitor commands. [J
PN
WITH microcomputers now so inexpensive, a large part of the|format and capable of working up to 112 cps (84 lines per
| cost of buying a system is in the peripherals attached to it.
The Anadex DP-8000 is one of the low-budget printers now| It has sprocket - feed as standard, and other standard features
include three interfaces — RS232C, 20/60mA loop and Cen-
Its capabilities show why it has been so sucessful. It is an| tronics — plug-compatible synchronous/parallel input, double-
80-column, bi-directional, dot-matrix printer using a 9 X 7 dot
(continued on page 59)
"or
57
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58 PRACTICAL COMPUTING September 1979
. Postcode ...
{continued from page 57)
width printing, 96-character set including upper- and lower-
case, capability to produce top copy plus three carbons, paper
entry through bottom or rear, out-of- paper detector, 1,024-
character storage buffer — an extra 2,048-character storage:
capability may be bought for approximately £30.
This enables a computer capable of high-speed data transfer to
run at that high speed, provided that characters transferred do
not exceed the capacity of the buffer; or provided hand-shaking
is employed, top-of-form and skip-over perforations controls,
eight programmable vertical tab positions, and off-line switch
which halts printing but retains data not printed in the buffer.
The serial interfaces can accept data at rates from 110 to 9,600
baud (switch-selectable) and character codes of 10 or 11 bits are
accommodated. The RS232C interface also generates a Data
Terminal Ready Signal to indicate when the internal buffer can
accept data.
The parallel interface can accept data at a maximum closed
loop rate above 1,000 characters per second and all control sign-
als are Centronics-compatible.
Internal switches are provided to program the printer to print
automatically CR/LF at the end of a line; initiate a CR/LF upon
receipt of a LF, VT, FF, or CR code only; truncate lines of 80
characters. Form length is also switch-selectable. The printer
uses continuous stationery, with Sin. between sprocket holes
(9.5in. paper).
The ribbon is a special matrix- printer type but is inexpensive
and changed easily in a few seconds.
One of the most important features is the versatility of the
Anadex. It can be, and has been, attached to most micro-
computers. We managed to run it with the Exidy Sorcerer which
is not entirely Centronics-compatible.
As far as availability is concerned, the prospects look good. So
far Anadex has tended to sell in bulk to anybody who will buy.
There are now plans to sell through recognised dealers and sys-
tems houses. This should make support and maintenance more
obtainable and reliable. At the moment, a private user would
have to send his machine to Kode Ltd, at Calne, Wiltshire, for
repair.
Heathkit
AS A RESULT of some complicated deal in the States, Heathkit
now call its printer the Heath Schlumberger Data Systems
Printer. To save time, we’ll call it Heathkit, as we have always
done.
It is an obvious comparison with the Anadex. After we had
looked at the Anadex we had the chance to try one of the first
Heathkits in the country. As far as performance goes, it works.
Data goes in and text comes out. To be honest, to that extent
there seems little difference between all the small dot matrix
printers.
They are all rather noisy, certainly too noisy to try to think
next to if they’re doing a good deal of printing. They all print
== data systems
printer
PRACTICAL COMPUTING September 1979
eS
quickly, they all produce rather horrible text — horrible, mainly
because the descenders in lower-case can’t be printed, and so
those letters are squashed up into the line.
So, to compare these printers, one has to look to secondary
features, and in comparing the Anadex to the Heathkit, we felt
that:
@ The Heathkit was packaged more attractively in a flat box, so
that one could stand cups of tea on it.
@ The Anadex produces slightly more pleasant letters — they
were less ‘dotty’ and easier to read.
@ The Heathkit was more flexible. It would print either 80 or
132 characters per line and this could be chosen by a switch on
the front.
@ A feature we liked about the Heathkit was that one could set
the form length into the machine from its front panel.
@ Heathkit was slightly faster. It would do a maximum 135
characters per second as against the 112 of the Anadex. On the
other hand, it has a print-head temperature warning light on the
front panel, which is on about half the time. If it lights all the
time, the printer stops to let the head cool. We didn’t have this
trouble but it might happen. :
@ Heathkit took wider paper — 9.Sin. as against 8in. on the
Anadex — and it could be adjusted to take paper down to 2. Sin.
wide. The Anadex would use only the one size.
@ Inside, the Anadex machinery looked rather more robust than
that of the Heathkit but Heathkit says that on test a machine
printed 150 million characters without a stoppage.
@ The Heathkit printer has an auto-test device; press a button
and it prints-out its repertoire of characters. This will at least
prove that it is not the printer which is at fault.
@ On the assumption that every machine breaks down sooner or
later, Heathkit looked the easier to cope with. The company has
a London shop where machines can be mended, a depot at
Gloucester which will do the same, and because it offers kits —
of this equipment as well as many others — it has a team of
engineers to answer telephone enquiries.
@ Because the start is made with a kit, the documentation is
excellent, and we felt that with the users’ manual in one hand
and a telephone in the other, one might often be able to get the
machine going again. A broken Anadex, on the other hand,
would have to be shipped to Kode at Calne.
Prices
Heathkit, assembled £553, in kit form £386.28. Anadex, assembled, £575.
Conclusions
@ In general, the Anadex DP-8000 looks good value for money.
It is versatile and relatively fast with some neat features. The
main fault is that it is noisy, which is not unusual for printers at
this price. On the whole it can be recommended for most small
business applications. -
@ We felt that the Heathkit was probably better value, though
not by a vast amount. Building the kit would save £150 and since
there is only one board of electronics in it, it would probably not
be difficult.
ue tee
tn ate
eet aM see
2, a Ad
Pn eee
59
Preserving the vital link
of comprehension
WHAT IS Artificial Intelligence? I will
give a quirky answer which should pro-
voke thought.
Figures 1, 2 and 3 depict three sup-
erficially similar games. They are Nim —
‘“‘standard” computation, given one
magic principle; Chess — ‘‘semi-hard”’
large catalogue of principles required.
Roadblock — for large versions ‘‘hard”’;
no principles exist.
Nim exemplifies the whole class of
problems which can be solved algorithmi-
cally, i.e. by compact computer programs.
At the other end of the scale, Roadblock
stands for a class of problems of high
inherent complexity. Except in trivially
small versions, they will never be solved
by any computing system.
It might seem that Nim and Roadblock
between them cover the whole range but
this would be wrong — the real action lies
in the no-man's-land between, a territory
which I have termed “‘semi-hard’’. In tak-
ing chess to exemplify this category, I
should remark that it has not yet been
proved to differ from Nim. A simple
mathematical rule for playing perfect
chess might still be discovered.
I do not know anyone who believes
this. Note, too, that the category exem-
plified by chess, soluble only by non-
compact programs stuffed out with large
bodies of knowledge-based rules, is the
category which also contains innumerable
socially-relevant problems of mental
skill.
Computing technologies are about to
break into this category on a large scale.
The question is whether the break-in
should be by AI methods modelled on
the human style of cognition, or whether
it should be by the brute-force
non-human representations and
strategies are those which on criteria of
machine efficiency show up as necessarily
more cost-effective in action. They are
also, pending radical advance in AI,
enormously cheaper to construct.
@ Hence design philosophies of the
humanising kind are likely to be swept
aside in the ‘‘advanced automation” rush
This issue of Practical Computing starts a series on Artificial Intel-
ligence which will, in the coming months, explore the basic ideas of
this field and show how they can be made to work on
microcomputers. in the first article Professor Donald Michie, head of
the Machine Intelligence Research Unit at Edinburgh University, and
visiting Professor at Stanford University in the United States, draws
some lessons from history and discusses the basic Al task —
problem-solving.
technologies of nanosecond processors
and trillion-bit stores.
Here are three fundamental prop-
Ositions:
@ No semi-hard problem can be solved
feasibly by computer program, unless the
program is enriched with a larger or
smaller catalogue of logically-redundant
heuristic information.
@ Solubility can be conferred by a wide
variety of such catalogues in each case
but very few will do it so as to preserve
human comprehensibility of the program
and its operations. Unfortunately the
Professor Donald Michie, assistant and robot.
60
the vital
for economic profit.
The 1973 disaster at Edinburgh — of
which more later — pre-figures in mic-
rocosm what may happen in the larger
world of technology if we are: not very
careful.
I fear that the havoc of the first indus-
trial revolution may be repeated on a
more uncontrollable scale. To explain my
reasons for this fear, let me repeat that
there are two ways to solve a semi-hard
problem by computer. The “‘brute force”’
way typically gives a ‘‘bigger bang for the
buck”. So it will be preferred by an
institution with clout.
Slow and costly
In the Artificial Intelligence way,
human representations of problem- |
solving know-how are built explicitly into
the program structure, thus preserving
link of man-machine com-
prehension. In the present state of the
art, ‘knowledge engineering” is a slow
and costly process. Research directed
towards automating it is thus the urgent
task.
In this country, however, AI tends to
be seen as, at best, an esoteric pursuit
and, at worst, a shocking expense. There
was a time when these snap judgments
possessed more than a little truth. They
have been once-and-for all unsnapped by
the microelectronics tidal wave.
My friend Ed Fredkin, Director of the
celebrated MIT Project MAC, asked me
recently about I. J. Good’s predicted
Ultra-Intelligent Machine, that ultimate
breakthrough when someone will exhibit
for the first time a machine — to steal
words from the calypso:
“Smarter than the man in every way”’.
Fredkin’s point was that with computer
power as cheap as water it may be a
PRACTICAL COMPUTING September 1979
ms Artificial Intelligencemmaaamm
hobby computerist who, in his home, first
works the trick.
I don’t go all the way with Fredkin but
I think that significant AI work can and
will be done. by home computer
enthusiasts, such as readers of Practical
Computing.
Let us consider robotics. Can hobbyists
build robots? In the U.S. they not only
build them but race them, in the regular
Amazing Micro-mouse Maze Contest. Yet
I regard those robots as boring, bad for
all concerned, and a waste of good talent.
The nature of the contest, running a sim-
ple maze against the clock, encourages
intense devotion to sensors, to mechan-
ical ingenuity, to clever circuitry, to cheap
software tricks — to everything, in fact,
which characterises the runaway technol-
ogy of the larger world outside, with
nothing of the more cognitive attributes
which make real mice more interesting
than micro-mice.
What technical objectives would be
encouraged by the more cognitive type of
contest? Humanly and nationally they are
not without importance. I believe that it
would apply a forcing function to systems
which should be to some degree teachable
and self-programmable.
Problem solving
Since our computing industries are fac-
ing a worsening programmer famine, the
timeliness and social relevance of such
goals cannot be in doubt and I hope that
the imminent announcement of a British
AI contest — to be sponsored, I under-
stand, by Practical Computing among
other bodies — will be a sign of the rever-_
sal of an unfortunate prejudice against
the discipline in this country.
The first and most drastic man-
ifestation of this prejudice was the with-
drawal in 1973 of Science Research
Council support for the Edinburgh Uni-
versity’s Freddy AI project. Britain’s
chances of leading in robotics R & D
were wiped-out for the foreseeable
future. Robots are not essential to the
study of Artificial Intelligence but Arti-
ficial Intelligence is as essential to
advanced robotics as aerodynamics is to
Figure |..A large game of Nim. There are 3! counters in each pile. Total
possible positions is similar to chess.
HTTEEETTEEEE ETE
LIVE EET
pile1 pile2 pile3
PRACTICAL COMPUTING September 1979
aero-engineering.
Still, enough of reproaches. How can
computers be taught to think? How can
they be made “artificially intelligent’?
The first problem to be solved in creat-
ing useful AI systems is to teach machines
to solve problems by themselves. On its
‘own, however, machine problem-solving
is nothing exceptional.
Like tic-tac-toe or the ‘*5-puzzle”
sliding-block problem, the class of prob-
lem may just be too easy to be inter-
esting. Alternatively, the problem may be
very hard indeed, yet perfectly-executed
computer solutions could be nothing but
a yawn.
In chess, the defence of king and rook,
against king and queen, no other pieces
Figure 2. Chess: “A very complicated
ition”.
pos-
being on the board, is so difficult that
against Master play of the queen’s side
there is almost certainly no person alive
who can solve it.
Moreover, for the queen’s side this
ending is known to be a theoretical win.
So it seems hardly surprising that the task
of averting defeat against Master play
should be beyond human powers.
Nevertheless, this task can be accom-
plished by machine-stored expertise, as
was demonstrated by Kenneth Thompson
at the 1977 meeting of the International
Federation of Information Processing in
Toronto. He challenged two strong
number of
TETTTTUTT EET
International Masters, Hans Berliner and
Lawrence Day, to demonstrate the play
of the king and queen’s side against a
king and rook’s defence conducted by his
program running on a PDP-11.
Naturally, the two chess masters
accepted the challenge, expecting an easy
time. To the amazement of onlookers and
their own deep mortification, they could
make no progress. Time and again new
Starting positions were set up, but in the
ensuing variations the Masters repeatedly
lost the thread. When play was aban-
doned finally the program remained
undefeated.
Surely, then, the computer way of sol-
ving problems in the KROR domain must
be very interesting, since it passes with
flying colours a gruelling test which
chess-masters would flunk. Not at all.
The machine’s method, however pow-
erful in this task environment, is in itself
uninteresting. The machine has memor-
ised a crib.
The total number of legal chess pos-
itions in the king-queen-king-rook end-
ing is about three million. So a complete
tabulation is possible, in principle, giving
for each position the optimal move. Thus
if it is a White-to-move position — sup-
pose that the queen’s side has the white
pieces — a move is entered in the table
WINS
BUGATTI
WINS
@> MOTORCYCLE
WINS.
{> BUGATTI
: a WINS |
Figure 3. A small game of Roadblock. The
running time of even the best program
increases as the power of the number of
intersections. This reflects the fact that no
improvement on brute-force search is poss-
ible.
which lies along the shortest forcing path
to checkmate or rook-capture. !
If it is a Black-to-move position, the
corresponding table entry will contain a
move which allows the length of the
residual forcing path to be shortened by
no more than one move — Black cannot
do better than that against best play.
A program for White which looks up
its next move in the table is guaranteed to
win in at worst the fewest number of |
moves needed theoretically to force the
win, and with any luck, if the defence
makes mistakes, in a good deal fewer.
Likewise a program for Black, such as
that with which International Masters
Berliner and Day had to contend, is
guaranteed to spin-out Black’s demise by
(continued on next page)
6t
62
(continued from previous page)
the greatest amount possible. If White
makes frequent small errors, or infre-
quent large ones, then the table-stored
strategy for Black may survive inde-
finitely, as the two hapless chess-masters
discovered. The longest optimal path
consists of 16 moves by White and [5
Black replies.
In remarking that perfectly-executed
computer solutions of very hard problems
can be nothing but a yawn, I do not imply
that what happened at Toronto was unin-
teresting. On the contrary, it was a grip-
ping, even disturbing, experience for all
present but the interesting phenomenon
was not the machine’s behaviour, but the
imperfection of Master performance.
This leads to intriguing questions about
its causes, which centre on the drastic
resources limitations of the human brain
relative to modern computing equipment.
The expert practitioner is obliged. to pac-
kage his knowledge into a set of sim-
plifying rules which he can carry in ‘his
head, even at the cost of being let down
by his rules from time to time.
Unlike the final stored look-up table,
Figure 4. Tabulation of all legal Noughts-and-Crosses positions which have been won by
Nought, the opening player. D, E and M correspond to “diagonal”, ‘“‘edge”’, and “‘middle”
winning patterns.
x
10 | Totals
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the process by which such tables can be
computed has something to interest the
reader, particularly if he has a home
computer with enough store to hold a
strategy table for games of non-trivial
dimensions.
Let us for convenience illustrate with a
trivial one, namely Noughts and Crosses,
called tic-tac-toe in the States. The
method of construction is applicable to all
games which, like chess, checkers, Go,
and five-in-a-row, are:
@ two-person;
@ finite — the rules censure that play must
eventually terminite:
@ zero sum — whit is good for one
player is bad for his opponent to an
exactly equal degree;
® perfect information — both players
have sight of the board and the moves;
@ without chance moves — no dice, ran-
dom draw of cards.
The idea is to start at the end of the
game ‘and work backwards. So we must
find a procedure for generating all the
terminal positions systematically. For a
table-based program implementing per-
fect play for both sides we need construct
only two sub-tables, one giving winning
play for Nought for all Nought-winnable
positions and the other giving Cross
strategy for all Cross-winnable positions.
If neither Nought nor Cross finds that the
current position is missing from both
sub-tables, that position is not winnable
by either side. The program then has a
theoretical draw and must avoid selecting
, a losing move.
Sub-table creation
Sub-table creation will be illustrated
for the case of building a winning Nought
strategy. After eliminating recurrences of
the same positions by mirror-imaging or
rotation, the number of positions won for
Nought can be grouped into 16
Noughts-only configurations, as in figure
4. From each of these, one or more pos-
itions can be constructed, according to
where the crosses are placed. The cor-
responding numbers are shown in the
right-hand column, making 77 to be
stored in all.
The next task is to construct all the
possible direct predecessors. They are
Nought-to-move positions winnable in
one move. They can be obtained by mak-
ing unit deletions in each position from
the three-noughts-in-a-row line. In other
words, we ask ‘“‘What could have been
Nought’s last move? Un-make it”. Going
back one step further we want to create
all the Cross-to-move predecessors which
are winnable for Nought. This is more
tricky. Let us start with D91.1 as an
example.
The first of the steps is straightforward,
and yields
O1O|x O1/O/Xx O|xK
° x ° x 9° x
x|x X|x/o x|x]o
Nougnht to move Nought to move
Nought to move
DIEIA D91.1B D9.IC
PRACTICAL COMPUTING September 1979
Next we try to find possible pre-
decessors of D91.1A winnable for
Nought — and draw a blank. Cross to
move can plug the corner square and win.
So, no table entry here. The next case,
however, yields a winnable-for-Nought
predecessor, and so does the last one,
D91.1C.
o|o O|x
° x °
x)x/o x|x/o
Nought-winnable
Nought-winnable
predecessor of predecessor of
D91.1B OPl.IC
The nought-winnable predecessors of
these are generated by deletion of the
“nought” which participates in both of
Nought’s potential winning lines, namely
the top left corner in D91.1B and the
centre of D91.1C. Other nought-
winnable predecessors, if the backwards
exploration is being done in systematic
‘“‘breadth-first’” fashion, will be found to
have been encountered already and
stored during backing-up from other
terminal wins.
Proceeding in this way, the strategy-
tree is grown backwards until it can be
grown no more. Here, then, in essence is
our table. The pre-terminal positions are
the “arguments” — to use the language
of schoolroom table-look-up — and the
moves are the ‘“‘values’, just as the
number 25 entered as an argument in a
table of square roots has 5 as the cor-
responding value.
A few details remain, such as the
occurrence of the same position more
than once at a given level in the tree.
These cases correspond to positions
which have more than one equally good
winning line.
Figure 5 shows another problem, a
one-person game. The ‘‘5-puzzle” shown
in the figure is a poor relation of the for-
midable ‘‘!5-puzzle’’. The latter, inci-
dentally, is discussed in the last published
writing of A M Turing, the great
mathematical logician and pioneer of
computing.
As far as its mathematical properties
are concerned, the 5-puzzle has been
polished-off in a page by P D A
Schofield, who points out an amusing
correspondence between the classes of
move-sequence in the 5-puzzle and the
axes of symmetry of the dodecahedron —
the twelve-faced perfect solid. This cor-
respondence arises because in group
theory both correspond to the same per-
mutation group, namely the Alternating
Group A5.
For any starting configuration of the
5-puzzle it is required to transform to the
es Artificial Intelligencemammmm
illustrated goal position in the minimal
number of moves. In the worst case this
minimum is 20 moves. There are 60 dis-
tinguishable starting positions — plus
another 60 which are insoluble and
ignored here — so that store require-
ments for a complete strategy-table are
even smaller than for tic-tac-toe. Con-
struction of the strategy table is easier,
too; the procedure is left as an exercise
for the reader using the basic facts about
the puzzle summarised in the figure.
Now for the point of comparison bet-
ween these two small problems. I spoke
earlier of problems “‘too easy to be inter-
esting”. What objective measures can we
use to characterise a problem’s difficulty?
Mathematicians have devised such meas-
ures, and they speak of ‘‘complexity’’.
For finite problems there are two dif-
ferent measures, namely the problem’s
Space-complexity — smallest number of
store-bits needed to house the complete
table — and time-complexity — smallest
number of operations required for sol-
ution in the case that it is to be solved by
pure calculation.
In terms of space complexity it is clear
that tic-tac-toe emerges as the harder,
since the strategy table has a few hundred
entries compared to only 60 for the
(continued on next page)
Figure 5S. The four positions soluble in four moves and the two positions soluble in six moves have been arranged and labelled to explain the
notation used in the strategy table for the six basic operations A, A—’, B, B— ', C, C—’. The first four operations correspond to move
sequences of length 4, the last two to move-sequences of length 6.
SOLUBLE BY
OPERATION A
SOLUBLE BY
OPERATION C
SOLUBLE BY
OPERATION C.1
PRACTICAL COMPUTING September 1979
SOLUBLE BY
GOAL
(12345)
SOLUBLE BY
OPERATION A.-!I
oaeen fo eae
SOLUBLE BY
OPERATION B
OPERATION B-|
63
(continued from previous page)
5-puzzle. It is equally clear that on pure
calculation the S-puzzle is harder.
This follows from the circumstances
that the only known pure calculation
adequate in all cases follows all possible
paths to the end of the game; and that
some paths, even corresponding to ‘“‘best
play’’, are as long as 20 moves. The com-
plete ‘lookahead tree” for tic-tac-toe has
an average branching factor of about 3
and a depth of, at most, 8. Corresponding
figures for the 5-puzzle are 2 and 20.
The number of nodes in the tree, prop-
ortional to the number of basic oper-
ations to be performed, is thus 3° and 2°°
for the two cases, i.e., 7,000 and
1,000,000 respectively. So on time com-
plexity the 5-puzzle is the harder.
The magic trick on which human cul-
ture and intellectual history have been
built, the trick of cognition, lies in ingeni-
ous compromise. Each of the two
approaches is of impractical cost by itself.
But the right blend can shrink costs
miraculously.
What does this blend look like? Let me
phrase the same question in the form of a
Condition-Pattern
total-distance =0.
preferred edge-pair
0 apart & edge-pair-
distance =0
preferred edge-pair
0 apart & edge-pair-
distance >0
preferred edge-pair
| apart & intervening
piece at place 2
preferred edge-pair
t aparc &
intervening piece
not at place 2
both edge-pairs
(Constraint)
(AA~ ', B, Be ')
(C.c- })
(A. B-')
(A-', B, C, C=)
(A-*, B)
table with a blank entry, as follows:
Approach
[. A try-everything program
2. What should we put here?
3. A situation-action dictionary.
1. Little store needed; but
runs for ever.
2. Store and computation
requirements both moderate.
3. Little computation needed; but
store requirement would more
than fill the world.
What belongs in the blank is a dic-
tionary of a kind but instead of zillions of
situations entered separately they are
grouped into a smaller number of
Situation-types. Instead of each entry giv-
ing an action as a result, an action scheme
is entered’ A scheme is some more gen-
eral structure — a set of goal-patterns
and constraints — from which actions can
be recovered by calculation.
So the new kind of dictionary is a dic-
tionary of patterns in place of individual
instances. Each entry, in effect, says to
Goal-Pattern
total-distance =O
total-distance is
reduced
edge-pair-distance is reduced
’ distance-of-
intervening-piece-from-
plate-2 is reduced
not (both edge-pairs
3 apart)
Note: A CONSTRAINT is applied as follows. Each operation in the bracketed list is applied in turn
to the current position and the resulting position is checked against the GOAL-PATTERN.
When a match occurs, the successful operation is selected and the Table is re-entered at
Rule |.
Pattern-directed “advice program” for the 5-puzzle generates near-optimal solutions at miniscule cost of
store and processor. The rules are taken in order, and the first whose condition-pattern matches the
current state of the problem is executed. Each rule Is interpreted in the style: given that the
condition-pattern has been matched then (using the constraint to reduce needless move-trials) find
a move-sequence which creates a match with the goal-pattern and then apply the sequence and then
re-enter the table.
Bundles of rules processed according to this regime are often referred to in Al work as “pro-
duction systems” owing to their resemblance to a formal scheme developed by the celebrated
logician E.Post. A neat and eminently revisable framework is thus provided for packaging useful
heuristic information about the problem, and keeping the resultant “knowledge-base” quarantined
from the “knowledge-interpreter”, which does the heavy-duty computation involved in search,
pattern-matching and the like. Such knowledge-bases can be treated as data and edited by program
— “machine learning” — to improve performance, or they can be modified or augmented inter-
actively by a human expert in the given problem-domain, thus exhibiting the desirable property of
“teachability”.
The important thing is that the level at which the problem is conceptualised in such sets of
pattern-based rules should correspond closely to the human's mental picture and thus lend itself to.
reciprocal transfer of knowledge between user and problem-solving system.
the processor: ‘“‘If the present situation
matches this pattern, then see if you can
work out a way of creating a new situ-
ation matching one of the following target
patterns, using only those actions which
match these constraint patterns?”
What this might look like for the
5-puzzle is shown in the pattern-directed
strategy-table from which we recover
general pieces of advice rather than indi-
vidual moves. Such a “knowledge-base”
of pattern-directed rules might be the
only way of getting a strategy into a
machine if the latter were a hand-held
programmable lacking enough memory
for the complete 60-entry exhaustive
tabulation. Needed definitions are given
in table 2.
The table’s strategy follows a well-
worn approach often called ‘problem-
reduction”, whereby the goal is decom-
posed into constituent features to be tack-
led separately. For the S-puzzle our
strategy sets the sub-goal “solve an edge”’
and then proposes solving the residual
problem.
It is common, as in the present case, for
such a sweeping simplification to sacrifice
the guarantee of optimality in the sol-
utions generated but if the solutions are
near-optimal the sacrifice may be judged
worthwhile, Table 3 gives the results of
running the ‘‘advice program” sketched
in table 1 on an LSI-11 micro, coded in
BCPL.
This last consideration comes to life in
the present context as soon as we realise
that the sub-goaling ruse adopted
generalises to sliding-block puzzles in
general. Moving to the 8-puzzle — 3x3
board, central square by convention
empty in the goal configuration —
problem-reduction takes the form solve
one of the four edges, and then solve for
the residual 5-puzzle.
Sufficient challenge
Clearly the technique can be pushed
higher and higher, to the 1 1-puzzle, the
15-puzzle, the 19-puzzle, and so on. For
a home micro owner, however, I would
suggest that a sufficient challenge initially
would be to extend to the 8-puzzle the
methods illustrated, using Schofield’s
Paper already cited as general back-
ground,
Best of all is the kind of program which
has so general a structure that different
knowledge bases can be slotted in and out
according to which puzzle is to be tack-
led.
If we raise the scale of problems to the
level of chess and the scale of the solving
device to the level of the trained human /}
brain, we can see the answer to an other-
wise puzzling riddle. Since pure search
takes us nowhere in such huge problem
domains, and since a complete strategy
table is also not a thinkable proposition,
how does the chess-master find good
moves?
Investigations by Alfred Binet at the
PRACTICAL COMPUTING September 1979
turn of the century, by Adrian de Groot
in the years after the second world war
and by Herbert Simon and colleagues
more recently, all point to the same trick.
It is based on amassing pattern-based
mental catalogues of the same essential
kind as the table of advice illustrates for
the toy example of the S-puzzle.
Other work suggests similar con-
clusions for skilled intellectual know-how
in general, whether in medical diagnosis,
plant pathology, chemical compound
| identification and synthesis planning, or
decision-taking in geological prospecting.
Computing systems capable of this kind
of practical thinking in specialist areas of
applied knowledge are called “expert sys-
tems’’.
Once the essential principle has been
grasped, it is within the resources even of
the micro hobbyist to build interesting
small systems of this type. The key prin-
ciple is that programs must be written in a
new way, namely in the form of modular
and incremental bundles of pattern-based
rules.
Position Program Optimal
12345 0 0
12453 10 10
12534 10 10
13254 14 14
13425 4 4
13542 14 14
14235 4 4
14352 14 14
14523 16 14
15243 20 14
15324 14 14
15432 18 18
21354 14 14
21435 20 18
21543 18 16
23145 16” 16
23451 Cu 6
23514 16 14
24153 20 16
24315 20 14
24531 10 8
25134 10 10
25341 4 4
25413 14 12
31245 16 16
31452 10 10
31524 20 16
32154 24 20
32415 14 12
32541 14
PRACTICAL COMPUTING September 1979
TABLE 2. Definitions required to implement the strategy of table 1, together with results
obtained with a version written in BCPL for the LSI-I1 micro.
total-distance: the sum of the five piece-distances, where
piece-distance =the shortest number of moves required to get the given piece home if all other
pieces are removed from the board — equal to the sum of the absolute values of the x- and
y-coordinate differences between present location and home location.
edge-pair: the piece-pair (5, 1) or the piece-pair (3, 4). In the goal configuration these two pairs
occupy the left-hand edge and right-hand edge respectively.
edge-pair-distance: the sum of the piece-distances of the two members of the edge-pair
preferred edge-pair: the edge-pair with fewer intervening pieces; in case of a tie, then the edge-pair
with the lesser edge-pair-distance: if still tied, then choose arbitrarily.
edge-pair n apart: starting with piece 5 (or 3 as the case may be) proceed clockwise round the board
counting the intervening pieces until piece | (or 4 as the case may be) is reached.
place 2: the location on the board occupied in the goal position by piece 2.
TABLE 3 Frequency distributions of lengths of solution-paths for the 5-puzzle.
Rules are invoked by processes of
matching with the current state of the
problem rather than by explicit sub-
routine call. The ability of pattern-
directed programming to steer between
the clashing rocks — between the Scylla
of processor-exhaustion and the Chary-
bdis of store-exhaustion — is as fun-
damental to the success of today’s expert
systems as the phenomenon of aerody-
namic lift was to the pioneers of heavier-
than-air flight.
It may be thought that something has
been said to illuminate the nature of
human cognition. Certainly these
machine models, the so-called ‘expert
systems”, throw light on one particular
aspect of cognition — the use of the brain
for routine execution of acquired skills.
Although this is the cognitive mode in
which most of us spend the greater part of
our waking lives, it occupies a fairly lowly
rung on the ladder of the intellect. The
next rung up is the ability autonomously
to acquire pattern-directed skills. In
learning from precept, from example and
Position Program Optimal
34125 16 14
34251 10 10
34512 12 12
35142 16 14
35214 20 16
35421 8 8
41253 16 14
41325 14 14
41532 14 12
42135 14 12
4235) 10 10
42513 16 16
43152 20 16
43215 18 16
43521 14 12
45123 12 12
45231 10 8
45312 16 14
51234 6 6
51342 4 4
51423 10 8
$2143 14 12
52314 10 10
52431 24 20
53124 10 10
53241 20 18
53412 10 8
54132 8 8
54213
54321
from practice, only modest progress has
been so far made by the mechanisers.
Above that lie regions of creative
insight and the higher flights of abstract
reasoning. Machine systems for these
higher levels still lie in the future. It may
be apposite to close with a problem due
to John McCarthy which is intractable to
pure search, to pure table look-up, and to
all mixtures and blends of the two. Yet it
falls apart when the right insight is
brought to bear.
The problem is posed in two stages.
The first is trivial. Can a checkerboard be
covered neatly with 32 dominoes, each
domino being of a size exactly to cover
two adjacent squares? Obviously, yes.
Now cut off the top left and bottom right
squares of the board. Can the mutilated
board of 62 remaining squares be tiled
with 21 dominoes?
If you think that your program might
be able to slug it out by trial-and-error
exhaustion of possible domino-tiling pat-
terns, then I merely multiply the board’s
dimensions by 10, so that it has 6,400
squares, and declare the essential prob-
lem unaltered.
Finally someone points out that each
domino covers exactly one white and one
black square. Initially there are equal
numbers of the two colours; but two
Opposite corner squares of an even-sided
board must be of the same colour, say
white, so that their removal creates a sur-
plus of two black squares remaining at
the end. Hence the even-sided mutilated
checker-board cannot be tiled.
This type of thinking lies beyond cur-
rent machine intelligence techniques.
Extensions will be needed to the present
tool-kit of computational logic before it
can be brought within reach. A later arti-
cle will review the present state of this
tool-kit, with some illustrative exercises
in ‘artificial reasoning” simple enough to
be run on a home micro.
Suggested reading
Ken Thompson (1979) Walter Browne v. Belle,
May issue of British Chess Magazine, gives the
results with commentary of two challenge games
between a strong Grandmaster and the KRKQ
database.
Articles by D. Michie and M R B Clarke in
Advances in Computer Chess 2, Edinburgh Uni-
versity Press, 1977.
AM Turing (1954). Solvable and unsolvable prob-
lems. Science News, London: Penguin, pp. 7-23.
P DA Schofield (1967). Complete solution of the
“Elght-Puzzle”, in Machine Intelligence | (eds. NL
Collins and D Michie) Edinburgh: Edinburgh Uni-
versity Press, pp. 125-33.
Readers interested in the connection between
machine problem-solving and certain issues in
robotics might look at two popularisations by D
Michie; Machine Intelligence at Edinburgh in Man-
agement Informatics vol. 2 (1973), pp. 7-12 and
Machines and the theory of intelligence, in
Nature, vol. 241 (1973), pp.S07-12.
mes Artificial Intelligence mam
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66 PRACTICAL COMPUTING September 1979
Until recently, the best computer algorithms were those where the programmer had
foreseen all the possible situations which might arise and designed a suitable
response. We examine how an old chestnut of a problem may be solved in a different
way, for instead of having to foresee every position, the program “learns” which
moves lead to defeat and discards them.
This approach means that you no longer have to worry in case you have over-
looked something and opens the possibility of the computer finding an original line
of its own — or teaching itself.
The problem
Although the approach is suitable for many problems, a new
target.
The method
The general idea is that you — the expert — play against the
computer and, if you win, the computer rejects the bad move it
made immediately prior to defeat. The computer must be able to
recognise when it has been in a given situation before and take
appropriate action. The apparent simplicity of a noughts and
crosses board, however, is deceptive. After the first move there
are nine possible situations:
aH +
tp tt th
He He
but each leads to a further eight possibilities when the second
player has his turn, and things get much, much worse. The enor-
mity of the task is shown in table 1.
Table 1
Number of Number of
moves possible patterns
|
2 9x8 = 72
3 9X8 x7 = 504
4 9X8 X7 X6 = 3024
I 5 9X8 x7 X6 x5 = 15120
j 6 9x8 X7 X6 X5 x4 = 60480
7. 9 xB X7 x6 X5 x4 x3 = 181440
8 9X8 X7 X6 X5 X4Xx3 X2 = 362880
PRACTICAL COMPUTING September 1979
concept is often best understood if it is seen within familiar sur- | least 5,611,761 bytes — owners of IBM 370s need read no
roundings. For this reason noughts and crosses seems an ideal | further; what follows is for the rest of the peasants.
Therefore the total number of patterns is a possible 623,529.
If each board were stored as a 3X3 array we would need at
(continued on next page)
Outline flowchart for the A.l. strategy.
Print the
instructions
Initialize move
and pattern
variables
Clear the
Board
Select the aig: aa anaes Get and
co r’s — i
Tae. move! ne uh
Print the
state of
play.
No
No Delete the
<> computer's
last move.
Yes Yes
Print Print
“| Win’ “Draw
sn
No
STOP
Saat _ SS ||
67
Noughts and Crosses aaa
Program which responds
when you beat it
Vl try harder next time. That is how Trevor Lusty’s learning prog-
ram for noughts and crosses responds when you beat it. Compare his
solution to Professor Michie’s on earlier pages.
(continued from page 67)
Some way of reducing storage requirements obviously is
needed and two ways are used:
@ Only the patterns occurring in play are stored.
@ Data packing is used to store the required pattern within a
single real variable.
The first of the ploys means that the computer must update its
file of stored patterns when it encounters a new one and, by
inference, it is not necessary to work them out before you start.
The data must, however, be stored in such a way that it is easy to
search, for the majority of the running time is liable to be spent
in this operation.
Besides the patterns, possible computer responses must also
be stored and, again, ease of use is vital. The computer would
prefer the board to be numbered 0 to 8, but for human con-
venience the playing positions are numbered:
1}2/3
4 6
7| 8/9
If, for example, the position after two human moves (Xs) is
the computer must store this state of play and the numbers 3, 4,
x/o
x
Figure |
Detailed flowchart of how the computer selects its
move.
Compute the
pattern No.
increment
Insert No.
into pattern
table.
Locate empty
squares and
compute move
number.
Insert move
number into
table.
Find first
non-zero in
move number.
Computer
plays in
corresponding
square.
68
5, 6, 7 and 8 which give possible computer moves. This latter
information may be stored as the nine-digit binary number
011111100 which is 252,10), where a zero represents an occupied
square and a one a possible move.
It is worth noting at this point that each bit of the binary
number may be set or cleared by the addition or subtraction of
suitable powers of 2, and the fact that we represent the numbers
in base 10 does not alter this.
Any position on the board has three possible states —
occupied by human; vacant; and occupied by the computer; and
base 3 numbers are more suitable for this. The position shown
can be represented by the base 3 number 201,111,112 which is
14,216 (10) and this is in many ways the most efficient.
For ease of computation and to preserve more of the original
structure, each row is computed separately and the result packed:
into a six-digit decimal number.
—— 201¢9 = 1I%1ig
Hey = 13¢19 191 ,314¢19
x H2¢3 = 1449
This representation works well for most machines but it should
be noted that the straight base 3 method saves space and may be
used with integer Basic. The method of storage is unimportant
as, once the pattern number has been calculated, it is used only
for comparison and no manipulation of the number is required.
Flowcharts
Flowchart 1 gives an outline of the strategy to be followed and,
with two exceptions, is. fairly straightforward. An example
helps.
Let us assume that the computer has reached the situation
shown in figure 1 for the first time, the sequence of events is
(see flowchart 2):
@ The computer works out the pattern number. (191314):
@ It searches the table of pattern numbers but does not find a fit,
so it inserts this new pattern into the table.
@ It computes the move number (011111100) as shown earlier
and decides to play in the first available position — square 3.
Now any reasonable human will play in square 5 and the com-
puter will lose. The computer notes the loss and removes the
possibility of playing in square 3 from its repertoire by setting the
third digit of the move number to zero, i.e.:
011111100-2 *-' = 011111000 (n.b., mixed bases).
Unfortunately, the computer still has to make one further mis-
take before playing the blocking move but, once learned, it is
never forgotten.
The program
Many of the possible patterns are duplicated and others are .
never reached because the game is already won. Also, the state
of play and possible moves are condensed to two simple var-
iables. The storage requirements are therefore not so great as
feared.
The state of play of the game in progress is held in the 3x 3
PRACTICAL COMPUTING September 1979
es NousShts and Crosses aa
is i I 2988 IF M9<9 THEN 1880
array B. The pattern number table is held in array T and the | 2°62 IF Nose &
corresponding possible moves in array M. 3020 PRINT "I WIN !!! --- DO YOU WANT TO TRY AGAIN "5
7 j i 1 i a 3048 INPUT AS
The dimension of these arrays is variable and snould Aiipeds: Fee oF aseevesy THENDLESO
ible, be set to a fairly large number, but a size as small as 20 | 3080 stop
locations is sufficient if you take into account the rotational and
A 1008 REM FEO OOO OOO RI IOI IG II I IRI IOI IIE ICI Fk aI IRE 2K
line symmetries of the board. ge es oc. eee |
: ‘ . : REM 2K AK IAL INTELLI
The program is written in a modular form with a number of | \g69 Rat aaeia is i samen had “.
subroutines. This means that it is easy to alter part of the prog- we ee CRORES ae
. + + . . ** * *
ram if your version of Basic is different. 1128 REM xeee* PROGRAMMED IN BASIC BY TREVOR L- LUSTY **¥#x
The win-testing subroutine counts the values of all possible |!!42 RB" hbase = ee
: : f 1168 REM PEecererrrreTErT Tete Tet Terre rere rere re tert errs fs et SS
lines and stores them in array S. A flag F1 is then set to zero, one | 1180 Rm&
. : 1208 DIM BUC3.33.TLC208].MC200]-S08)-AST18]-L30 3)
or negative one depending on the State of the game. 1226 PRINT “THIS 1S A GAME OF NOUGHTS AND CROSSES WITH THE BOARD"
The squares of the board are referred-to in two ways:— 1248 PRINT "NUMBERED AS FOLLOWS :-"
1268 PRINT
1266 PRINT "1 I 21 3"
i213 1,1 1,2 1,3 1300 PRINT "==I===1==
1320 PRINT "4 ft 51 6”
and 2,1 2,1 2,3 }194@ PRINT "=2I===1=="
3,1 3,2 33 1368 PRINT "7 181 9"
7\|8|9 1388 PRINT
1498 PRINT “YOU MAY BEAT ME AT FIRST» BUT I LEARN FROM MY MISTAKES"
|1420 PRINT "AND I NEVER MAKE THE SAMEMISTAKE TWICE - - YOU HAVE"
and the short subroutine starting at line 3100 is used to convert | 1/74 print "BEEN WARNED 11"
from the first to the second. 1460 PRINT
Line 2200 deletes a bad move and is easy to understand, pro- |'4° PRINT “WE WILL TAKE TURNS* >= YOU WILL BEX I SHALL BE ©
vided you remember that 1 = 2°. 1500 REM wxxex INITIALIZE VARIABLES *
. + soe eee
The printout shows the initial attempts of the computer and | j523 Let Ls="x.0"
how it improves after a few moves. i at
158@ LET TlQ)=8
1606 LET MCQi=511
Conclusions
@® The game is surprisingly interesting to piay,a8 10000 | 5 ao ee ee ee
develops into a situation where you must think of new ways to |164@ FoR Ni=1 To 3
a bee 5 * 1668 FOR N2=!1 TO 3
win, and this is not as simple as it appears. Recut Nase een MnP
@ It is possible to adapt the program so that the machine plays |17¢@ NExT Ne
against itself a given number of times before it plays you. This
1720 NEXT NI
i Se 1748 =PRINT
removes some or all of the bad moves and makes it difficult to
beat.
1768 PRINT
178@ PRINT “OK =-- LET'S START =<-- "3
@ The most successful and enjoyable ploy, though, is to win the
first 12 games easily and then invite a friend — not for long — to
1880 LET M9=0
1820 REM xk DECIDE WHO STARTS ** 4%
try to do the same.
1840 LET M7=M7+1
1868 IF M7=2*INTCM7/2) THEN 2280
1888 PRINT "WHAT IS YOUR MOVE "Ss
2080 REM awe HAS OPPONENT WON 2? ¥**¥** 1900 INPUT H
2188 GOSUB 3280
21260 IF Fl=1 THEN 2280
2148 IF M9<9 THEN 22808
2168 PRINT "DRAW --- I MUST BE GETTING BETTER-"
2188 GOTO 1648
2200 LET MCQ2)}=MCQ2)]-2t¢P2-1>)
2226 PRINT "1 CONCEDE --- YOU WIN. --- I'LL TRY HARDER NEXT TIME”
2248 GOTO 1648
1926 REM x*xke* CHANGE MOVE TO COORDINATES ***#x*
1948 GOSUB 3128
1968 IF BCY-X1=@ THEN 2048
1988 PRINT “ILLEGAL MOVE --- PLEASE TRY AGAIN"
2000 PRINT
2828 GOTO 188¢a
2040 LET BLY-X]=1
2068 LET M9=M9+1
2260 REM ax*eeex COMPUTE PATTERN **#xx
2280 LET T2=8
2306 FOR Ni=! TO 3
2320 LET T1=9*(BIN1].11+1)+3*(BINI,2]+1)+(BIN1,31]+1)
2348 LET T2=T2+T1*(181(2*N1))
2368 NEXT NI
3188 REM xeeee CONVERT TO COORDINATES X AND YL *****
312@ LET Y=INTCCH-1)73)+1
3146 LET X=H-3*CY-1)
3168 RETURN
3186 REM *xeex TEST FOR A WIN **##x
3208 FOR Ni=!1 TO 3
3226 LET SCN1IJ=BCN1,11]+B(N!,.2]+BCN1, 3]
3248 LET S(N1+3]=BC14N11+Bf2.N11+BL3-N1]
3268 NEXT NI
2388 REM xeeee SEARCH TABLE ****x
2488 FOR Q1=! TO @
2420 4IF TLQ!11=T2 THEN 2668
2449 NEXT Ql
2468 REM xeeKK INSERT NEW POSITION IN TABLE ****a-
2480 LET @=Q15Q+1
2508 LET TCQ)}=T2
-2528 LET MCQ]=@
2548 FOR Ni=1 TO 3
2560 FOR N2=1 TO 3
2580 IF BCNIsN2) <> @ THEN 2628
2608 LET MCQJ=MCQI)+21C3*(N1-1)+¢(N2-19)
2620 NEXT N2
2648 NEXT NI
3288 REM xeeee OTEST DIAGONALS) ¥eeHK
3386 LET §(71=BC1.11+Bl2,21+BL3.31
3320 LET S€81=BC3.1)+Bl2-2)+BC1.31
3348 REM **e*** SEARCH TABLE FOR A WIN) ***x*x
3368 FOR NI=1 TO 8
3388 IF SCNIJ=3 THEN 3488
3480 IF S[N!1]=-3 THEN 3528
3420 NEXT N1
3448 LET FI=@8
346@ RETURN
3480 LET Fl=1
3508 RETURN
352@ LET Fl=-1
3548 RETURN
2668 REM x*k** FIND COMPUTER'S MOVE ***#*
2688 IF MCQ1J=@ THEN 2208
270@ FOR Pl=1 TO 9
2720 IF MCQII/C2TP1)> <> INTCMCQLI/¢C2tP1)) THEN 2768
2746 NEXT Pl!
2768 LET Q2=@!
2780 LET P2=P1
2800 PRINT “COMPUTER PLAYS POSITION ";P1
2828 LET H=P1
2848 GOSUB 3128
266@ LET BCY-XI]=-"I
2880 LET M9=M9+1
3566 REM xe*k** PRINT THE BOARD *****
3580 PRINT
3688 FOR Ni=1 TO 3
3628 FOR N2=1 'TO 3
3648 LET M8=2-BCN1.N2)
3668 PRINT LSC(M8-MBI5" "5
3688 NEXT N2
3788 PRINT
3720 NEXT NI
3748 PRINT
3768 RETURN
3788 END |
2908 REM x*xeee PRINT THE BOARD AND TEST FOR A WIN) **#**
2928 GOSUB 3582
2949 GOSUB 3200
2968 IF Fl=-1! THEN 3828
PRACTICAL COMPUTING September 1979 69
t= 2% 3a 47 5s 6% 73 9S
Winy waiik for @ Krill
computer Wihem you
cam buya fully wilt Gaara
€ tested Superboard TR wea
Off tine sinellf? Stee
— —_——
( Delivery within 7 days)
Ohio Scientifics
SUPERBOARD Ill ~~
Full 8K basic and 4K user RAM Built and tested
Power supply and R.F. Converter P.O.A.
instruct it or program it to do whatever you want, but you don’t
have to. You don't because it comes with a complete software
library on cassette including programmes for each application stated
above. Ohio Scientific also offers you hundreds of inexpensive
programs on read-to-run cassettes. Program it yourself or just enjoy
it, the choice is yours.
The machine can be economicaliy expanded to assist in your
business, remotely control your home, communicate with other
computers and perform many of the tasks via the broadest lines
of expansion accessories in the microcomputer industry.
This machine is super easy to use because it communicates naturally
in BASIC, an English-like programming language. So you can easily
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 expandable tu 8K
@ Full 53-key keyboard with upper-lower case and user
programmability
@ Kansas City standard audio cassette interface for high
reliability
@ Ful! machine code monitor and 1/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.
Commands
CONT
Statements
CLEAR
GOTO
NEXT
REM
LIST NEW NULL RUN
DATA DEF DIM
GOSUB iF..GOTO — IF...THEN
ON...GOTO ON...GOSUB POKE
RESTORE RETURN STOP
END
INPUT
PRINT
FOR
LET
READ
Expressions
Operators
—, +, ",/,f, NOT, AND, OR, >.< <> >=, <== “ _
RANGE 10°° to 10
Functions
ABS(X) ATN(X)
LOG(X) PEEK(I)
SPC (1) SQR(X)
String Functions
ASC(X$) CHR$(1I)
COS(X)
POS(1)
TAB(t)
FRE(X)
SGN(X)
USR(t)
EXP(X)
RND(X)
TAN(X)
INT(X)
SIN(X)
FRE(X$) LEFTS(X$,1) LEN(X$) MIDS
(X$,1,J).
VAL(X$)
Extras
@ Available expander board features 24K static RAM (ad-
ditional mini-floppy interface, port adapter for printer
and modem and OS! 48 line expansion interface.
@Assembler/editor and extended machine code monitor
available.
(Wy)
RIGHTS$(X$,)) STRS(X)
Plus variables, arrays and editing facitities.
Fully built and tested. Requires only +5V at 3 amps and a videomonitor or TV and RF converter to be up and running.
MAL Eine MaAQaZIMEsS sEaLU)
“The Superboard represents good value with plenty of potential”
Practical Computing June ‘79
“Certainly one of the most exciting (computers) on the present market”’
Practical Electronics June ‘79
““A useful machine represents value for money”
Computing Today June ‘79
Dealer Enquiries welcome at Morgan St. address
Watford Electronics _
Videotime Products Lotus Sound
33/35, Cardiff Road,
Watford, Herts.
Tel: Watford 40588/9
56, Queens Road,
Basingstoke, Hants RG21 1REA
4, Morgan Street,
London E3
70
Tel: 0256 56417
Tel: 01-981 3993
@ Circle No. 173
PRACTICAL COMPUTING September 1/979
Kay Floyd toured the North-west to look at microcomputing in
its various aspects. She reports visits to a “Software cottage’’, a
computer shop and a board manufacturer.
Happy to stay local
THE WORD consultancy conjures-up opul-
ent offices, with several Chester Barrie-
clad young men wandering around with
important-looking leather briefcases —
to my mind at least. So it was something
of a surprise and a delightful shock when
I visited B&B Consultants in Bolton to
find one of the principals soldering an
interface together and the other in his
cardigan explaining to a misguided
woman that they couldn’t fix her dentures
— she needed the dentist upstairs.
John Blackburn, who started the firm,
is a good-humoured Lancastrian and
describes himself as ‘‘a salesman with a
management background’. He runs the
firm with Peter Binks, who takes care of
the technical side, writing programs and,
in this instance, making an interface
which Blackburn was preparing to take to
a customer.
The company was set up about a year
ago and the showroom has been open
since early 1979. As well as the con-
John Blackman with the Pet.
PRACTICAL COMPUTING September 1979
sultancy and shop, B&B Consultants is
heavily involved in microcomputer
software.
It is writing packages for the garage
industry (spare parts and stock control),
insurance brokerage (financial and client
records), finance house (financial and
client records), employers’ personnel
records, plumbers’ stock control and
Price list, estate agents’ package, stock
control in relation to electronic man-
ufacturing and, finally, yarn converters
which contro] a textile manufacturing
process from the reel of cotton to the
invoicing of the finished material.
Selling aid
The cost can range between £150 for
the payroll to £1,000 for the insurance
brokerage, depending on how much work
and modification of a standard package is
involved. “‘We see software as an aid to
selling machines,” say Blackburn, ‘‘not as
+ snot =
ane
rs
eat x
rit heen
a big money-maker.”
There is a small range of educational
software available which includes maths
and programming, and one program
which aids the deaf with their speech. As |
well as its special packages, B&B Con-
sultants stocks off-the-shelf lines from |
Petsoft, Commodore and the PETACT
range.
The software indicates that B&B Con-
sultants is heavily involved with the Pet,
and although it is the company’s best
seller, Blackburn explains:
“We can supply anything advertised.
The Apple, Horizon, ITT 2020, Exidy
Sorcerer. You name it, I can get it, but we
don’t stock them in quantity.”
The consultancy has recently taken
a dealership for the revolutionary TECS
system, the full-colour computer which
can turn a domestic television into a
Teletext-cum-viewdata facility.
“I think it’s one of the biggest things to |
hit England,” says Blackburn. But. he
won’t be giving up the Pet yet.
In the market
“I think Pet is a good machine, the
price is right and it’s readily available.
For the small business it is ideal.”’
Blackburn has put the machine to good
use in local businesses. He has attached a
till to it and sold it to a two corner shops
as a sophisticated cash register. When a
receipt is issued to a customer, the Pet
updates the stock order automatically,
thus cutting out a good deal of paper-
work. These modified Pets have been
installed with a tobacconist and a toy
retailer. The staff don’t want to be com-
puter operators, says Blackburn; people
are buying the latest business machines
which happen to be computers.
Blackburn is doing his best to dispel
the myth of the computer by taking it to
every local exhibition, computer course
and demonstration in the area. Once he
took a Pet to the town centre, set it up in
the middle of the market and proceeded
to demonstrate its capabilities. It drew
terrific crowds and, he says, ‘‘I did a lot of
good business that day’.
He stood in the foyer of the local
technical college when it ran its one-day
(continued on next page)
7
f
(continued from previous page)
management course, attracting a good
deal of attention. In fact, that particular
attendance paid off, as he has received an
order worth £4,000 from Bolton Techni-
cal College for systems to be used in a
full-time computer course.
B&B Consultants works on a simple
system. “I find the customer, define the
problems and give them to Peter to
solve”, says Blackburn. “We have a good
team. I can sell and Peter handles the
technical side. The two things go hand in
hand.”
There is one other person working
full-time on the administration side and
two part-timers. “‘I am seriously looking
for full-time programmers,” says Black-
burn, ‘‘so that Peter is left free for more
design work.”
Binks writes almost all the software
and is the technical back-up service.
Occasionally B& B Consultants enlists the
aid of another company to write the
financial packages which are very time;
consuming and not really Binks’ forte.
‘*He’s good at number-crunching and
that kind of thing,” says Blackburn.
Customers are found by advertising in
the local press and national computer
journals and then there are those who
visit the showroom. He is mainly con-
cerned with the small businessman but he
will cater for the hobbyist if necessary.
B&B Consultants would like to do
more design work and is marketing its
own interface. It drives a Teletype or
other serial printer and it was one of them
which Binks was soldering during my
Visit.
Blackburn feels that the interfaces on
the market are over-priced and do not
always work properly. His own model
sells for £75 and can run both bi-
directional and single-directional prin-
ters. He thinks there is a need for a stan-
dard computer-type interface on the
market and hopes that this is it.
Most of B&B Consultants’ assignments
are in the Bolton area. “I don’t par-
ticularly want to become a national firm,”’
says Blackburn. “I'm happy to stay
local.”
He also believes in the personal touch
when dealing with customers. ‘‘I don’t
want to be a mail order house. The com-
petition here is healthy but we try that
little bit harder. If anyone comes into our
showroom, they will not be ignored, as I
have seen happen in some places.” — J
Shop route to success
HAVE YOU ever thought of starting your
own computer shop? It may seem like a
snip. You think you know enough about
computers, and you’ve heard that there’s
a fortune to be made from selling mic-
rocomputers to the unsuspecting public.
Well, it’s not so easy as it sounds, as I
discovered when I spoke to Bruce
Everiss, chairman and managing director
of Microdigital. He describes the draw-
backs and gives advice to the would-be
shopkeeper.
Everiss started Microdigital more than
a year ago, with his brother as the only
full-time member of staff. Since then it
has flourished into a successful mail order
house, a hire company and, of course, the
shop through which many of the big
orders are made.
When he started, Everiss admits he had
no real business experience. He had been
running a dp department when he real-
ised he really wanted to be involved in
microcomputers.
Raising finance
“I played it by ear and asked advice
from my father, who’s a_ successful
businessman and I had a friend who owns
a chain store. I had a good deal of help
| and asked for advice when I got stuck,”’
he says.
The first thing to do was to raise
finance. “I went around begging for
money,” he said. “‘It is always the prob-
lem, even now.” The next thing was to
secure dealerships from various com-
panies, so that he had something to sell.
“IT just telephoned suppliers and got
the dealerships — it was as simple as
that.” One of Microdigital’s luckiest
breaks was getting a dealership from
Nascom. **No-one else on Merseyside can
sell it,” he said.
When Everiss had some cash and deal-
erships, the next item on the agenda was
72
to find suitable premises. Having always
lived on Merseyside, it seemed a natural
choice to base himself in Liverpool.
“It was very difficult to obtain a shop
here,” he says. “It cost us a small for-
tune.” But he found one in the ‘‘city”
Bruce Everiss
area, the financial quarter where the
banks and lawyers are located.
Why did he choose that site rather than
a popular shopping precinct? ** Business
— that’s where the future of mic-
rocomputers lies,’ he maintains. He
wants to be on the spot when the financial
world realises it.
Everiss knew that if he was to make a
success of the venture, he would need a
good back-up service. Initially he sub-
contracted all the necessary engineering
work. ‘*A number of people came to help
us. We used a number of moonlighters.”
That was not an ideal situation and
Microdigital recently has employed a
number of engineers with whom it is to
establish a professional workshop to deal
with repairs and development work.
Finding good staff who know about
microcomputers is difficult. They are rare
and very much in demand. ‘‘I have been
lucky with my staff: They found me, I
didn’t have to go and look for them,” says
Everiss. Most of them are ex-customers.
In the city area of Liverpool, Everiss
realised there would not be many people
calling to buy £3,000 worth of equip-
ment, so he devised a way of generat-
ing additional business quickly. It was the
mail order firm, based on all items sold in
the shop. Setting it up was “‘a matter of
survival”’ and Everiss now receives more
than £1,000 worth of business a day
through it.
Prompt service is essential. **The goods
or a letter of acknowledgment is sent the
day the order is received.”
Believer
Another important consideration is to
define the market. It's no good trying to
attract the hobbyist with a Sorcerer and »
it’s rio use trying to attract the business-
man with something like a MK14. Mic-
rodigital caters for both markets, as well
as the computer engineer. The Acorn,
MK14 and Nascom serve the hobbyist
sector, and for the small business user
there is the Apple, ITT 2020, Pet and
Exidy Sorcerer.
Finding the right staff, premises and
financial support were all obstacles on the
path to success but Everiss maintains that
“judging how to advertise was the most
difficult thing’. He now writes all his
advertisement copy himself and believes
that it is one of the most important
aspects to any business.
“You sell only what you advertise’’ is
his motto. Certainly, Microdigital adver-
tisments are prolific. Everiss advertises
locally as well and has had a series of
posters distributed to manufacturers and
PRACTICAL COMPUTING September 1979
a eres Foo) 0
even has them displayed in the Merse-
yside underground system.
Microdigital has a few other products
on the sidelines, to enhance systems,
including discs and printers. One of the
best-selling lines is cassette tapes — an
average of 100 a day leave the shop.
Everiss tells what led to his involve-
ment in this lucrative trade. “I realised
that there would be a shortage, so I went
to a manufacturer who made special
tapes. They are top quality and people
can use them at very high baud rates.
“We sell more of our tapes than Com-
modore or Petsoft,” he claims. ‘*They,
incidentally, have now gone to the same
manufacturer, but I sell the tapes
more cheaply.”
Books and magazines also constitute a
large part of the business, with more than
£20,000 worth in stock. Along with the
Nascom-1, books are the biggest money-
spinners this year.
A frequent problem with setting-up a
shop is obtaining the supplies. ‘Cus-
tomers are always harassing you,” says
Everiss. “I take a lot of stick over this.”
Microdigital is undoubtedly successful
Boards in the attic
YOU COULD not find two companies more
dissimilar in operation than our last man-
ufacturer, Nascom, and Kemitron Elec-
tronics, although they both make the
same product — computer boards.
Kemitron is a small operation run by
John Drury from the attic of his Chester
home. The peaceful countryside, the
wife-secretary and tea in the garden
seemed a long way from the swish offices
and large manufacturing facilities which
one comes to expect in the computer
industry.
Drury trained as an electronic chemist
— hence the name — Kemi from chemist
and tron from electronic. After working
for Shell for several years, he decided
that life in a multinational wasn’t for him.
He began on his own three years ago.
He planned to base his business on elec-
trochemical equipment and designed a
multimeter to start the venture. ‘Sinclair
did one at the same time and that was the
end of that market,” he said.
Drury then allied himself with Crofton
Electronics and, while there, designed his
microcomputer. It was not a happy ven-
ture and Drury left Crofton in 1978, tak-
ing his design with him.
Exceptional
His microcomputer, the Kemitron
UBS 3000, is made up of a series of mod-
ular boards which you can plug into a
rack to any configuration of your choice.
The computer has an exceptional bus
structure which is simple and cheap —
less than half the price of the S100. The
boards range from £5 to £6 and include
such things as memory, PROM, pro-
cessors and VDU.
' Drury has perfected the technique of
putting several processors on to one bus.
He works with the 8060, Z-80, 8080 and
is looking at the possibility of the 6502
and the 6800.
| Kemitron is one of the few firms to
work with the National Semiconductor
SC/MP. ‘“‘Most people think it’s a useless
processor; I don’t,” says Drury. He has
re-written the Basic software for the chip
and it now runs faster than the National
PRACTICAL COMPUTING September 1979
version.
He became involved with National
through the SC/MP introduction kit,
which uses a calculator-like display. He
found it difficult to work with, so decided
to design a VDU board for it. When
National heard of his work with its pro-
cessor, it was naturally interested, and he
now works closely with the company.
He has just taken delivery of a new
processor from National, the 8070, and
Drury reckons that it is “more powerful
than the Z-80". He has written the
operating system and the resident assem-
‘
John Drury
bler for the processor and is hoping to
base a single-board computer on it for
around £100.
Drury most enjoys the creative side of
his work — designing boards and prog-
ramming. The administration and sales
side of the business has become too time
consuming, so Drury has a partner to
help.
“T always said I would keep it to one
man but that has proved impossible,” he
says. ‘‘The company will grow and I will
expand the workforce to an optimum of
15 people.”
Kemitron is obviously a small oper-
ation, so I was intrigued to discover
where the manufacturing of the boards
was done. They are produced under sub-
contract, by outworkers who call once a
week to deliver the finished goods.
but it hasn’t been all plain sailing. “Pve
been unlucky at times,” says Everiss. “I
bought unsaleable stocks and created
demand when there were no supplies.
The business made a loss from April to
September last year when we started.”
It seems that you should not be dis-
couraged when things go wrong, and
learn from your mistakes.
Does Everiss have a final word of
advice for anyone wanting to set up 4
shop? ‘Specialise,’ he says. “Choose
software, interfacing or robots, and make
sure you get plenty of publicity.”’ Q
‘*T was surprised by the initial response
I had to an advertisement for assemblers
in the local paper. There were 200 appl-
icants, so there will be no shortage of
workers when I want to increase pro-
duction. Each worker produces between
30 and 40 boards a week. The potential is
tremendous,” he says.
With so much work on the technical
side, something has to suffer in
administration and Drury admits that
marketing is a ‘tweak link”. He would
like to expand his distrubutor network —
he has two — and generate additional
systems business.
He does a little advertising and runs
training courses at Leeds Polytechnic. He
uses his own systems on the course and
students often want to buy them when it
is Over.
Profit maxim
Drury says that he is not the ‘business
school type’. “It’s more profitable to
grab opportunities when they come. I
think this policy pays. At the moment I
have one job which could run into 100
units. They are all Z-80-based for one
specific application.”
So far, he has sold some 20 systems,
costing anything between £800 and
£1,000. No precise figures are available
for company turnover, but “‘it is increas-
ing all the time’’, he says. He is looking
for more than £100,000 this year.
Drury’s formula for success is simple,
“High volume equals low profit. Small
volume equals high profit. There is high
profit in applications, and elec-
trochemistry is high-profit throughout. I
want to weld computers and elec-
trochemistry together.”
What of the future? ‘We shall be
developing software support and looking
to new processors. We are hoping to lay
out the 6502 on a processor card, and
develop a rival to the Ohio Superboard.
That market sector is crying-out for a
product and the Superboard isn’t here to
fill it. Ours will probably be a little more
expensive but it will be modular and have
an edge connector.
73
74
WHYMARK
Instruments Lid
201 TALLY ROLL PRINTER
Available with motorized take up for copy.
301 DOCUMENT PRINTER
Prints lines of 40 characters on right hand
side of any size form.
401 LABEL PRINTER
Prints standard 3% ins width labels for
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All the above printers feature:- 40 characters
per line, software control of 4 character sizes,
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can produce multiple copies. Interfaces to
IEEE 488, RS 232, Parallel TTL etc.
Direct connections for P.E.T., Apple II.
WHYMARK INSTRUMENTS Ltd
6 Holmesdale Road
Reigate, Surrey, RH2 OBQ
Tel enquiries (04254) 77012
@ Circle No. 174
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PRACTICAL COMPUTING September 1979
A
OEM quantity price £295
Pudsey is test-bed
for Elite system
THE PROJECT was set up at Priesthorpe
Comprehensive, Pudsey, Leeds, with the
help of headmaster Ian Philp. ‘The
experiment has resulted in the design for
a machine which should fulfil most of the
requirements for both computer edu-
cation and computer-assisted education,”
say Peter Jackson, commercial director of
MBS.
“The machine is an upward-
expandable model which enables the
school to buy, in small increments, a
sophisticated piece of equipment which
will cope with requirements of assembler
language and machine-code prog-
ramming and the needs of the depart-
ments within the school. It is also capable
of tackling administration tasks, such as
ficult,” says Philp, “‘but it helped to find
out that what was going on inside the
machine. Now we can write simple Basic
programs and make our own mistakes.
“Purely from the company point of
view, the whole thing was an exper-
iment,’ Philp continued, ‘‘but one in
which the school was delighted to take
part. We had been thinking about getting
a computer in the school before we were
approached by MBS, but there was the
financial problem and also that of who
looked after the machine, as none of us
had any experience. So it looked as
though there was no way we could have
one .until Jackson stepped in and was
prepared to help us.”
The installation of the machine has
MANY SCHOOLS using established microcomputers for computer
studies have received attention from Practical Computing, but this is
the first report on a school which has been the test-bed for a new
computer — the Modular Business Systems (MBS) Elite — which has
been built to teachers’ requirements.
computerising school records, within the
school budget.
“The MBS Elite is designed around an
all-in-one concept which encloses VDU,
central processor and disc unit. External
video outputs are provided to drive
monitors which are found at most
schools, and the overall size is deter-
mined by the standard school trolley.
“The machine can be expanded in
memory capacity and disc storage by the
addition of several cards. The standard
operating system was designed for use
with high-level languages, CP/M and a
comprehensive Basic. It was designed for
and specified by teachers.
Priced competitively
“The system is priced competitively at
around £4,000 to meet the tight budgets
of many schools. This has been made
possible due to the upward-expandability
of the system and because MBS is able to
rationalise on cost and avoid overheads
usually found in the field of man-
ufacturing activity.”
Jackson became involved with Pries-
thorpe Comprehensive a year ago
through one of the maths teachers. “He
felt there were strong reasons for going
into a school which had no experience
with computers,” say Philp.
Jackson gave the teachers lectures on
how to use the system and they referred
to books and anything else they could
find to increase their knowledge.
“We started programming at the
assembler stage, which was a little dif-
PRACTICAL COMPUTING September 1979
meant that a new and exciting future has
opened-up for Priesthorpe Com-
prehensive in the computer field. Philp
envisages computer studies, with
software written by the pupils, some
standard packages and others which will
be modified by the school.
Computerised learning is high on the
list and Philp hopes to put together some
software for remedial maths and English
classes. “Some students have problems
with the basic rules of numbers and with
simple maths programs and a computer, I
feel that this totally different approach
will do much for the student. If he can see
the old problem in a new and exciting
way by using the computer, it will give
him prestige and confidence, as well as
increased motivation,’ Philp explains.
The MBS Elite
Students who will use the machine
range in age from 14-18. The computer
studies will start gradually with a small O
level group in the sixth form, then an O
level in the fourth year with a limited
number of students and, hopefully, a
higher examination for older members of
the school.
The administration staff expect the
machine to be a great help to them. “I
don’t think it can run the whole school
records,’ Philp says, ‘but it will keep
basic records, which include production
of form lists in alphabetical order and
transfer of classes.
“This will be very useful, as we have
many students who join us halfway
through the year. It takes a great deal of
secretarial time and the computer will
simplify things like that. We hope to put
book-keeping on it as well.”
Something for all
Education am
One point Philp stresses is that the ,
computer is there for everybody's use.
“The big danger is that it may become
something for the maths teacher and his
classes to play with — I want to prevent
that,’ he stresses. .
**As soon as we get to the stage where
the machine is instantly available to any-
one, then we will accept it as being a use-
ful addition to the school.
“T will do anything to encourage peo-
ple to use the computer. It doesn't matter
what they do with it — even playing
games helps. The fact that young people
are using it is the most important thing.”
There are around 1,000 pupils in the
school and “‘if in five years’ time, every-
one in the school has not had some
benefit from it, or experience with it —
whether it be seeing it in action or operat-
ing it themselves, I will be disappointed,”
says the headmaster.
75
SPECIALISTS IN
MICROCOMPUTERS
We care about what leaves
our factory. After all it’s got
our name on it.
The next time you want
reliable microcomputer
products — single card
computers, floppy disk
systems and disk systems —
take alook at what we putin
our DOXxes.
AComart Computer Catalogue will
show you.
SPECIALISTS
Write to
43 comart
Comart Ltd., P.O. Box 2, St. Neots,
Huntingdon, Cambs.
Or telephone (0480) 215005.
76
@ Circl
_ cle No.
CTICAL COMPUTING ae hi
es Viicrocomputer Centres
Is the time ripe for a
technology centre?
THE GROWTH of sales of microcomputers
over the next 10 years will be astounding.
There are, for instance, some two million
small businesses, a high proportion of
which will be able to make economic use
of a micro. In addition, many lower-level
managers in large firms and many home
users will also be buying micros.
If you don’t believe that such a sudden,
widespread sale is possible, look at elec-
tronic calculators. Did
Firstly, we need to regain our position |
in terms of international competitiveness.
Secondly, if we want to have our own
micro industry, rather than importing
everything from the Americans or the
Japanese, we need a home market to
build sales before we export.
For those reasons the Government is
spending money on telling people about
microprocessors and encouraging their
help to improve the quality of hardware
and software by publishing unbiased and
objective comparative data — in the way
WHICH COMPUTER? and Practical Com-
puting do in the magazine field. It would
help to improve reliability by collecting
feedback from users. The Centre infor-
mation would, of course, be available to
suppliers and consultants, as well as to
the public.
The important thing is
that the information
you have a calculator in
1969? Did you know
what they did or how to
use them? How many
small businesses are
| without one today?
Now computers may
not spread at the speed
of calculators — which
took only five years —
but the increase will still
be fast.
Microcomputers are
much simpler to under-
stand than bigger
machines and_ their
Operating systems. This
is just as well, because
almost all the micros
sold in the future will be
bought by people who
know nothing about
computing today.
WOULD YOU like to be able to use an independent Mic-
rocomputer Centre to find out about micros? By the time you
read this, the author, Ian Litterick, hopes to be carrying-out a
feasibility study to see whether such a centre-should be estab-
lished, and how it should be run. It would form part of the
Government programme to encourage small businesses and the.
application of microprocessors.
Similar to the Design Centre, Building Centre or Crafts
Centre, the Microcomputer Centre would probably be based in
central London, with an exhibition area showing systems running
and available for the public to inspect.
A library and book-shop would form part of a service which
would provide comparative information on hardware and soft-
ware, as well as a broader education about micros in general.
The Centre might also run satellite centres in regional cities, or
“travelling circus” caravans visiting smaller towns, or run stands
at trade exhibitions.
The author would like to hear the views of Practical Comput-
ing readers, particularly micro-users or would-be users, on the
proposal and on what the Centre should do. Please write to him
care of Practical Computing.
would have a very low
cost to the “client”.
Traditionally intorma-
tion — like software —
for computers has been
very expensive. If you
are installing a £40,000
minicomputer you think
nothing of going to a
three-day seminar for
£400 to learn about
com puting, or of emp-
loying a consultant at
equal expense to make
recommendations.
it, however, you are
to spend only £2,000-
£3,000 on a system, you
will not spend hundreds
of pounds getting in-
formation about it.
Worse, many of them distrust it, are
afraid of it, dislike the jargon and mystifi-
cation which surround it, and are gener-
ally anti-computer.
Yet it is important that, as a nation, we
adopt the new technology at the fastest
possible rate, for two reasons.
use, and it has also shown great interest |
in the idea of-a Microcomputer Centre.
The Centre is regarded as a means of
providing the education and information
needed to progress from complete ignor-
ance of computing to buying a system.
In the process, the Centre would also
So the Centre will need to avoid the
| face-to-face information-giving which is
so expensive. Literature, designed care- |
fully to give the information you need
without confusing you with jargon, or .
things which are irrelevant to you, will-
probably be the main medium.
Microcomputer Centres — our view
IN PRINCIPLE what Ian Litterick suggests is perfectly correct and
the need for such centres has been felt, and to some extent, met
in many other industries. There is always, however, a fundamen-
tal difficulty about impartiality. Such a centre is either funded by
the industry through a voluntary levy or by some outside source,
like Government, a trust or a university.
In the first case the job of the Centre is regarded by the people
who pay for it as being to protect their interests; and therefore
they resent it publishing ‘unbiased and objective data’, much of
which is likely to be uncomplimentary. In the second case, it
tends to settle into stodgy inactivity as the best way of avoiding
pressure on its backers.
The only organisational escape is through building an ‘editor-
trade or Government. That is part of the function of magazines
like this, and it is one we can partly fulfil.
Of course, if we decided that every manufacturer of software
and hardware in the microfield produced rubbish, we might find
ourselves short of advertising revenue; to that extent, we are not
and can scarcely be absolutely impartial. No-one who earns a
living by selling advertising space could properly discharge the
functions of the Centre.
One of the few organisations to escape has been the Consum-
ers’ Association. To make enough to ensure an unbiased exis-
tence, however, its publication, Which? has to appeal to a huge
number of people, by surveying the widest possible range of
goods and services — from divorce lawyers to cat-mange cures.
It is most unlikely that an organisation devoted solely to mic-
ial reputation which is worth enough to its consumers to give it) rocomputing would be strong enough to withstand the pressures
an independent existence, apart from the good- or ill-will of] which would be ranged against it.
PRACTICAL COMPUTING § September 1979
va
‘HE STARED at the video screen on which each player was trans-
formed into a moving dot of light and each movement into a silver
A whole
snail’s trail.’
78
new ball game
PRACTICAL COMPUTING § September 1979
SSS SST Re te
Mackinaw, the referee, had an idiosyncrasy. At the start of each
game he would not toss a coin. Instead, he used a large, silver
medallion, won by a great-grandfather in some forgotten war. As
he spun it in the air it caught the sun and sparkled. For three
seconds it silenced the roars and shouts from the throats of the
50,000 crowd.
The audio-microelectronics were baffled temporarily by the
moment of silence; they over-reacted by sending the banks of
phallic sound booms sliding out on their telescopic arms to hunt
from side to side; and the commentators saw the sparkle and
pressed their lips to the microphones to explain about Mackinaw’s
idiosyncrasy to the watching millions.
The panels of experts in the sterile studios made notes on their
pads; the scene was scanned by dozens of electronic eyes; and it
was torn into shreds and pumped straight up the long antennae
and streamed out through the stratosphere towards the huge
weightless dishes; and the space stations scooped up the signal and
cleaned it, tidied it and magnified it with the power from the sun
and then pulsed it out, bouncing it around the globe from wire to
wire, component to component.
Never a chance
In the double-glazed Alaskan huts, and the rain-soaked slums
of Rio, and the tar-paper shacks of Johannesburg, anonymous
people stared into cathode ray tubes and were joined in spirit with
the boisterous crowd.
by John Abbatt
City won the toss, Carter kicked-off and passed to Wardle, who
back-heeled to Thompson, who ran round a defender, feinted
left and then hit a high cross ot Malloney, who leapt high into the
air at precisely the right moment and nodded the ball perfectly to
the feet of Fairclough, who belted it solidly into the top right-
hand corner of the net. The defence didn't stand a chance.
Nobody congratulated Fairclough and, as he walked back to his
position, he gave a thumbs-up sign to the glass-fronted City
control box high in the West Stand.
In the box was Strickland, the City manager; squat beneath his
archaic trilby hat, his lips clamped on an unlit cigar. He had given
up smoking but retained the cigar for the image. He had binocu-
lars slung around his neck and headphones over his ears. At
intervals he spoke into a microphone. He spoke to a man who was
lying flat on the roof of the stand with glasses trained on the rival |
United contro! box.
Faraway look
In the corner of the box, not even looking at the game, sat
Mullen, the aged trainer, and Polchard, the groundsman. They
had dragged out an old and well-worn relic of conversation and
were tossing it between them.
“Charlie George, Kevin Keegan and George Best,” said Mul-
len. * They had style and a feel for the game. They were artists.”
Another roar outside. One-all.
“Goalless draws,” prompted Polchard. “Do you remember
goalless draws? Now it’s 20 or 30 goals a game.”
Mullen nodded. They were real teams; squads we used to call
them. Now you pull them off of the street and in six weeks they are
PRACTICAL COMPUTING § September 1979
{
top-class players. When they are injured you throw them aside
and get another one.”
All for a few weeks of glory,” said Polchard, ‘but nearly all the|
money goes to them.”
He nodded towards the other side of the box where Dearlove,
the chief tactician, stared at a video screen, on which each player,
was transformed into a moving dot of light and each movement
into a silver snail’s trail. Beside him was Walker, the principal
programmer, peering at another screen full of bunches of figures
and characters.
Walker looked up. “Analysis read-out, Jim. That was one of|
their disc Beta attacks, track 3G.”
Dearlove punched B3G into his console and looked at the
screen again. ‘In that case we can stay with our Omega Disc and
try attack 8Z. None of their defences on that disc can handle it.”
Secret weapon
He punched more buttons and on the field the players!
responded. Carter kicked-off again and four minutes later Mal-
loney had the ball in the net. Two-one.
Strickland clutched at his earphones. ‘‘He says they are chang-
ing discs,” he shouted.
Dearlove and Walker looked at one another.
You know what the model predicted,” said Walker. ‘‘They
should be trying their Gamma disc attack 4J at this stage if they
are being consistent.”
Dearlove nodded. So now we try our secret weapon, we'll give
them the new Alpha defence, 9Q."
Walker already had the diskette in his hand and he pushed it in
the slot as Dearlove keyed-in the code. The battery of 11 anten-
nae below the box swivelled and locked on to each member of the
team.
A fresh beam of micropulses was generated and sped unerringly
to activate the pressure pads superglued between the shoulder
blades of each player. The 12 pressure points in each pad were
invoked. Each man responded as he had been trained; trained to
react blindly and without thought to the patterns of pressure as
they came. Swerve. Right. Leap. Kick. Shoot.
As the United winger executed a beautifully-positioned pass,
Fairclough, to the delight of the crowd, got a head to the ball by
split-second timing and nodded it down to the feet of Carter.
Right,” said Dearlove, excitement lifting his voice, “now we
hit them with a 7C.”
Mr. Fixit
He punched-in the code and two minutes later Thompson
scored with an incredible shot. He had his back to the goal and
kicked the ball backwards over his head. Three-one.
There came a whistle and the cigar tell out of Strickland’s
mouth. **The referee's given us offside,” he said.
He turned to berate Dearlove but then touched his earphones.
**He says to look at their aerials.”
He focused his binoculars on the other box. ** Twelve of them,”
he announced.
He panned downwards and fastened his gaze on Mackinaw. He
could just make out the tell-tale circular shape under the back of
the man’s shirt.
He turned again, letting the binoculars fall to his chest.""O.K. so
they must have fixed the ref. Get the jammers out boys — we ve
got a fight on our hands.”
79
NEWTRONICS KEYBOARD TERMINAL
FQUINOX 300
A powerful multi-user
multi-tasking
multi-language
16-bit nucrocomputer time-sharing syster
supporting
* BASIC
; “UEISIF
The Newtronics Keyboard Terminal is a low-cost, stand-alone * PASCAL
Video Terminal that operates quietly and maintenance free. It will F g
allow you to display on a monitor 16 lines of 64 characters or 16 Floppy discs
lines of 32 characters on a modified TV (RF Modulator required). ’ ‘Hard discs
The characters can be any of the 96 ASC11 alphanumerics and
any of the 32 special characters. In addition to upper-lower case including a powerful Text Formatter,
capability it has scroll up features and full X-Y cursor control. All Assembly Language Development System
that is required from your microcomputer is 300baud, RS232-C or and disc-based Sort utilities
20ma loop, serial data, plus a power source of 8v DC & 6-3v AC.
The steel cabinet is finished in IBM Blue-Black. And if that is not
enough the price is only £135°55 + VAT as a Kit, or £17500 + Priced from under £5,000
VAT assembled and tested. Plus £2:00 P & P.
Dealer and O.E.M. enquiries invited. ‘
To didlet, pitoneor wiitetor: Write or phone for further information
i 138 KINGSLAND RD. LONDON E2 EQUINOX COMPUTER SYSTEMS LTD
Nawironias 8BY. TEL; 01-739 1582. ‘ :
a Kleeman House” 16 Anning Street
Manufacturers & Distributors of : : ; =
High-Fidelty and Electronic Equipment New Inn Yard. London EC2A SAB:
‘lel: 01-739 23879. 01-729 4460,
Access/Barclaycards accepted.
@ Circle No. 178 @ Circle No. 179
POWERHOUSE 2
Microcomputer
Z80A microprocessor. 16 or 32k byte of dynamic RAM
Central processor, RAM, PROM/EPROM, Keyboard
encoder and serial 1/O interfaces on one p.c. board
@ Space for two further option boards
— True X-Y graphics
— IEEE 488 interface
— Additional serial 1/O channels
— Customer designed boards
Mini cassette option, built into standard housing
Interfaces with up to four mini or standard floppy discs
Genuine desk-top unit — 43 x 28 x 17 cms; 6.4 kg
Centronics interface on main board. Extended BASIC in
EPROM (optional)
® Standard software controls all functions including screen
editing
POWERHOUSE MICROPROCESSORS LIMITED
5-7 ALEXANDRA ROAD
HEMEL HEMPSTEAD
HERTFOR'DSHIREsHP2 5BS
Telephone: (0442) 48422 Telex: 826339
@ Circle No. 180
80 PRACTICAL COMPUTING September 1979
ss (56 2c Solr a
Same and Different —
Letter Builder
Cassette for Apple, Per and TRS-80
Levels | and Il. Available from Program
Design Inc, 11 Idar Court, Greenwich,
Connecticut; $9.50.
THIS American package software house
advertises a range of educational soft-
ware for Pet, Tandy and Paale, it claims
its programs to be of tested educational
value. We bought the Apple version
using VISA, and it took some four weeks
to arrive.
Incidentally, it is very easy to buy US.
products using Visa or Masterchange or
Amex Credit cards — much easier than
sending a dollar draft. Whenever possible
we use this method of payment, always
assuming, of course, that the vendor can
accept the credit cards.
Same and Different is a Suite of six simi-
lar programs in which the pupil (target
age 3-6 years) starts by identifying as
‘same’ or ‘different’ a range of large col-
our squares. It then moves on to increas-
ingly-complex letter-like shapes — like
large boxes, and plus and minus signs —
and finally to matching ordinary screen-
sized letters.
Letter Builder takes this process a stage
further but the pupil has to find the letter
displayed on the keyboard which is dis-
played on the screen. Again the level of
| difficulty can be selected, starting with
distinctive letters (A and S) and moving
by stages to the whole alphabet.
Smile, please
The program is accompanied by a six-
page leaflet. For Same and Different this
tells you to put ‘smile’ and ‘sad’ faces on
the S and'D keys on the keyboard, and to
screen the rest of the keyboard with
cardboard.
We didn’t think young children would
be too happy with this arrangement, the
experience of some researchers in this
area is that large buttons are preferred to
small keys. So we altered the program
slightly (line 350, and print statements in
140 and 18Q) to use H instead of S to
separate the letters. We then made some
large keys from: plastic wall hooks from
Woolworths, which were loose on top of
the keyboard keys.
We used Loctite Handystrip on the
bottom of the keys to provide a shape
which would slot over the keys — an
alternative might be Bluetack or some-
thing similar. The extension keys were
held in place by the cardboard screening
the rest of the keyboard.
Baby Suzanna being still too young to
try, we took our Apple to a day nursery.
There six four-year-olds tried Same and
Different.
The conclusion was encouraging. All
the children eventually grasped the idea
after some patient explanation by the
matron. Just as important, they enjoyed
the exercise. A little to our surprise, two
PRACTICAL COMPUTING § September 1979
managed the level 6 stage of Same and
Different ‘matching letters. The steady
rhythm of changing patterns and the ‘well
done’ and ‘raspberry sounds, which |
thought well-chosen, seemed to hold the
children’s attention well, although a
longer test would be needed to see how
this persisted.
One weakness in the arrangement was
that the children tended to concentrate
on the colours on the screen and not look
too carefully at the keys. They disting-
uished keys as much by touch as by sight.
Next time we tried keys with different
shapes and textures, and spaced them
further apart at the edges of the
keyboard, so the children had to turn
clearly from one to the other. That
seemed an improvement.
As to the educational value, it should
take an elaborate, controlled test to
prove the worth of the computer in rela-
tion to traditional instruction. For our
review each child was supervised closely
and encouraged by one of the staff. The
exercise, however, seemed reasonably
convincing as a development aid.
Convincing
The main defect from this point of view
is that the letters are capitals. Children
are taught normally to read and write
using lower-case letters. Apple high-
resolution graphics could be used with
advantage to overcome this particular
problem.
We also thought the reinforcement
could be improved by some special dis-
play after, say, 10 correct answers. The
programs score for the child but this is
not directly to provide feedback.
The crux of the matter, however, is the
children. They like the programs and |
was convinced they were learning to look
at shapes in the way they need to do to
learn to read.
They definitely liked the programs.
Better advice could be given on making
the keys distinctive to the child but the
price is very reasonable — as an educa-
tion aid you may not have to pay duty or
VAT — and there were no technical
hitches. — K..F.
Escape
Templeman Software Services, PO Box 7,
Stratford-on-Avon, for cassette or mini-
floppy in 16K. No price decided.
MOST computer games are abstract enter-
tainments. Startrek, for instance, is an
almost completely intellectual business of
dots and numbers, though, if one had to
‘fight a deep space battle with the Kling-
ons, this might well be how it felt.
Adventure is played through text mes-
sages on the screen, all the visual settings
have to be erected in the player's head.
We have found one game, however,
which is both intellectually gripping and
visually striking. It uses the Apple graph-
ics to create a crude but astonishingly
compelling world from which you have to
Escape.
On the surface, it’s just another old
maze. What you see on the screen is your
view as you stand in a maze with 10-ft.
walls. If you have colour, better yet —
because the sky, walls and floor are dif-
ferent and this adds to the realism.
This view takes the top half of the
VDU,; below it is a little map of the direc-
tions in which you can move at that par-
ticular position in the maze, and the keys
to press to execute a change.
Gripping
So, if you want to turn round and see
what's behind, you hit the appropriate
key. If you turn round again, there’s the
scene you had to begin with. If you move
forward, turnings to left and right appear
— you can look down them, go down
them or pass on. As you explore the
maze, you can sketch a map of the bits
you've seen and traversed. But every so
often you meet a denizen of the labyrinth.
You were warned that these people
either always tell the truth, sometimes lie,
or always lie. Each will make some cryp-
tic remark like ‘} always lie’, which must
mean that he sometimes lies because if he
always lied he would have to say ‘] always
tell the truth.” He will offer a map of the
maze but, since he may not be truthful, it
may be misleading; and a compass which
will indicate direction but, of course, it
may be a ‘joke’ compass.
By correlating all the information from
the maze, the maps, the denizens and
their compasses, it is possible to find a
way out.
There is nothing esoteric about the
computing for this sort of game. The
essential ingredient is imagination —
making it possible for the player, or vic-
tim, to see things realistically.
For instance, it seems that the new
computer games on the West Coast are
about ‘contact’ sports. In a basketball
game we’ve heard of, the players run and
twist and their faces show pleasure,
anger, pain, frustration. This is the way
games must go. Why can’t the U.K. pro-
duce some? — P. L. pA
8|
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ee ee eee eee eee es ee ee eee ee
@ Circle No. 18!
82 PRACTICAL COMPUTING September 1979
ee SE: SEN ee ee 20 a ta
Peanut Butter and
Jelly Guide to
Computers
By Jerry Willis. Published by
Dilithium Press 1978 (distributed
by ISBS); paperback, 207 pages;
price, £5.80.
WHETHER it’s the fact that this
book was written on a word pro-
cessor or that the author is a
specialist in instructional materials
and methods which is responsible
for its readability is anyone’s
guess. But it is, and it covers as
much of the computer field as
some books twice the size.
It’s possible to write a book on a
subject about which you don’t
know a great deal but that will cer-
tainly show in what you write. On
the other hand, if you know your
subject it will be clear in the
finished work. Willis obviously
knows his subject. He has learned
a good deal, the hard way, about
assembling kits and buying
second-hand peripherals and writ-
ing programs,
Satisfying
It would be no exaggeration to
say that you'll obtain more solid
information from this book than
you would in several months of
other reading. The details make it
a satisfying read, plus the feeling
that you re getting good, friendly
and unbiased advice from a fellow
fanatic.
The book includes introductions
to micro architecture, memories,
languages, a run-down on some
typical computers, as well as sec-
tions on simple applications and
computer art. The final three
chapters cover the author’s
experiences with computer stores,
mail-order buying and kit build-
ing. Most of it is U.S.-orientated,
predictably enough, but let us
hope that some of the sad stories
are not repeated here,
The only real complaint we
could make is on his explanation
of number systems. It is not the
best we’ve seen, perhaps because
it’s compressed into three or four
pages. There are plenty of better
introductions to the subject.
Conclusion
@ If you're a beginner, you'll learn
plenty from this book. It’s espe-
cially worth reading if you're
thinking of buying your first
microcomputer. The author has
succeeded in his aim “to keep
the writing style as light and
comfortable as possible and to
include technical material only
if it would be helpful and under-
standa@ble to a reader who didn’t
have # degree’. Highly recom-
mended.— R.G.
‘ews co:
a
The Future with
Micro-Electronics
By lann Barron and Ray Curnow.
Published 1979 by Frances Pinter
Ltd. hardback, 243 pages; price,
£7.95.
THE HEALTH of Practical Com-
puting is a living witness to the
future outlined in this important
book, probably the first practical
— as opposed to science fiction —
assessment of how the micro will
change our lives. It was written
originally for the Department of
Industry early in 1978 to help
shape government policy in rela-
tion to micro-electronics, mic-
roprocessors and microcomputers,
and it aroused controversy at the
time because of its “leaked” pro-
jections of the unemployment
which might result from the micro
revolution.
It estimates the number of jobs
lost as 10-15 percent and a high
proportion of them will be today’s |
female jobs. Will this result in
more equal opportunities for
women? Or in a drastic decline in
female employment?
The main lesson of the book is
that we must plan for and so
minimise the bad social
economic consequences of this
huge dislocation; and to maximise
the chances of replacing the lost
jobs. tronically, it seems the only
way to do so is to make sure that
we embrace the micro revolution |
at least as quickly as anybody else.
Five percent only
That is not so much because it is
important to replace redundant
jobs with a healthy microcomputer
industry, although Barron has now
become director of strategy at
Inmos, the deposed Labour gov-
ernment’s answer to Texas
Instruments and Motorola.
For, the authors argue, micro
electronics will never provide
more than five percent of the
economy, even if tele-
communications is included; as
fast as the volume of turnover
soars the cost per item plummets
and the labour input also drops.
So, overall, there is little growth.
No, the main reason why we
must embrace the micro revolution
is that unless we use the damned
things we will become totally
PRACTICAL COMPUTING. September 1979
and |
uncompetitive — an undeveloped
country by international stan-
dards. The Japanese, Americans,
French, Germans, Koreans and all
will be using them — and indeed
are using them — to produce
goods and services much more
cheaply than we will be able to do.
Fortunately, recent gov-
ernments and some of the unions
— at least at TUC level — are
beginning to realise the impor-
tance of accepting the challenge of
the micro. The question is whether
OF not it is too late and whether or’
not our built-in resistances to
these innovations can be over-
come.
The major part of the book is
the authors’ forecast of how the
technology will develop and how it
will be used. They cover a wide
area, from international packet-
switched networks and main-
frame computers to mic-~
Toprocessors and home com-
puting.
Too difficult
They don’t believe in the
“computer-controlled home’. It
would have to be programmed by
the owner, and programming, they
think, is too difficult for the man in
the street. Rather, mic-
roprocessors will be hidden for
specific activities in the same way
that electric motors are taken for
granted today. Did you know that
the average home has some 15
electric motors? Count your own.
Barron and Curnow predict that
solid-state memory — ROMs and
RAMs — will continue to get
denser and cheaper. Discs and
tapes, which are so slow, bulky
and unreliable, will be superceded
for storage by plug-in solid state
silicon.cassettes, at one-hundredth
of today’s cost.
In the longer term, perhaps we
will access books and _ records
through the public information
network, of which Preste! is the
beginning.
The other major development
which will affect the hobbyist
market is the electronic typwriter.
It will have a_ solid-state flat
screen, probably using liquid cry-
stals and of A4 size. The flat
screen should appear by the mid
“80s and in the long term the elec-
tronic typewriter should cost no
more than a calculator today.
The television, on the other
hand, they say, has no role to play
in the long-term development of
the home information system.
Other changes in the way the
householder receives information
would be:
@selective radio and TV
ordered over the telephone.
@ direct access to libraries.
@ newspapers transmitted by tele-
phone or radio.
@ far more specialised information
services — e.g., On sports.
@ remote shopping and ordering.
@ home electronic mail, delivered
electronically to your computer
rather than through the letter-
box.
Social problems
In home, factory, and, above all,
in the office, the electronic revolu-
tion will have a major effect on
how we live; but time and again
the authors emphasise that it is
social, not technological, problems
which must be overcome if the
revolution is to happen at the
Necessary speed. They are pes- |
simistic that they can be overcomé
quickly enough.
They identify two types of bar-
rier to achieving the necessary
adoption of micros in this country
— the question of who derives the
benefits and who suffers; and the
problem of awareness.
The first is the problem as seen
at Times Newspapers. The
typesetters stand to lose their
livelihood not to mention
public respect for their hard-won
skills — if single key-stroking
takes over, as it must be expected
to do in the long term, Single key-
stroking is when journalists type
their copy directly on to the com-
puter which will produce plates for
printing, so eliminating the need
for typesetting, which has until
now been a skilled and very
highly-paid job.
The second critical problem is
awareness. Most people know
nothing about computers or what
they do, except that they are vag-
uely hostile to them because they
go wrong, and that they cannot
understand the computer jargon.
Removing fears
There is a huge job to do
informing people about com-
puters, removing their fears,
de-mystifying them, providing
them with the information they
need to decide for what they can
use micros, help them to choose
the right hardware and software
for their needs, and learn how to
use it.
This book is the most important
effort to explain the micro revolu-
tion so far. All the more pity,
therefore, that it costs almost £8,
though which, I suppose, is only
the cost of a computer games
program.
Conclusion
@ This book is probably the first of
many about the micro-
electronic future. It is expensive
and sometimes too dry and
technical. Many of its ideas and
suggested policies are now old
and widely-accepted.
@lts views and projections are
important and deserve wide
consideration, particularly by
anybody who wants to keep
ahead of the electronics game.
— LL.
83
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 -technical data and
unbiased critical 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 ///ustrating Basic
(October 1978 onwards).
All this makes Practical Computing the invaluable
source for the whys, wherefores, hows, ifs and buts of
microcomputing.
October 1978
Review |: Commodore Pet I. Review 2:
VDUs- Computer Workshop CT-64,
Strumech Engineering ACT-1. Music ona
KIM; Micro v. Calculator; VAT accounting
complete program Part |
November 1978
Review: Tandy TRS-80. Projects for KIM
Pet goes to school; VAT accounting
complete program Part 2; Complete
game program - Mastermind; Software
Dynamics Basic compiler review.
December 1978
Review: Research Machines 3802.
Choosing your first computer; ITT inter-
view; Complete games programs -
Battleships. Racing Cars and Monsters;
A mi¢rocomputerised reservation system
Turning [185M
typewriters
into terminalis
Learn
by computer
January 1979
Review: Nascom L Convert an IBM
typewnter into a terminal Part 1; In-car
computing - Pet in the Panther DeVille
Report from the Los Angeles Computer
Faire ; Pascal v. Basic.
Ready-made
computer systems
for stock cantral
We review
single-board
computers
Tandy Forum
& Pet Comer,
Putting payroll Senool
On a computer computer
' Project
Low-cost
peripherais s
é
February 1979 March 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.
June 1979
Reviews: Compucolor I}, Ohio Super-
board Ii; Low-cost word-processing;
Computing ina pharmacy; Designinga
small business application Part 1;
Computer v. Brain; Zombie game
Choosing your
fret computer
rage-page gusde
Review: Single-board computers for less
than £50. Low-cost stock-control systems;
IBM typewnter conversion Part 3, New
monthly column -Tandy Forum; Complete
game program -NIM
July 1979
Reviews: AIM-65, SOL-20. Choosing your
first computer, Interfacing Pet with a
mainframe; Nascom story; Designing a
smail business application Part 2;
Biorhythms program.
April 1979
Review: North Star Horizon. Business
accounting systems; Apple Il design story
Part 1; Computensed school meals;
Finance for schoo] computing; Build your
own frequency meter, Star Trek game
August 1979
Reviews: Pet !I, KTM Pros andcons of
PASCAL; Microcomputer user groups;
Designing a small business application
Part 3; Interfacing Pet with a mainframe
Part 2; Life game program
May 1979
Reviews: Exidy Sorcerer Science of
Cambndge Mk 14; Printers for less than
£1000, Order processing/invoicing
packages; Retire with your computer,
Apple II design story Part 2; Slalom qame
To keep your copies of Practical!
Computing in good condition and
convenient jor reference you will need
a special binder in blue, with Practica!
Computingin silver-style lettering on
the spine, each holds twelve issues
Only the above issues are still available. Fill in the coupon opposite and return it with your remittance to
Practical Computing, 30-31 Islington Green, London N] 8BjJ.
PRACTICAL COMPUTING September 1979
If you buy the wrong
personal computer,
you cant re-program your
bank account!
Buying a personal computer is not an easy task.
So many people selling them neglect the little things that enable you
to get the most from your computer, such as documentation, spares, add-ons and
maintenance. We believe that these ‘details’ are essential. We are the only British company
to put all our time and energy into the personal computer market and are in the best
position to advise you on your initial purchase and keep you fully
informed about all the new developments relevant to your computer.
Personal Computers Limited — the name of the game.
Say ‘hello’ to a graphics Apple II A business Apple Il Exclusive to Personal Computers Ltd.
German Apple II. Available shortly.
Dersona
Computers
imited
194-200 Bishopsgate, London EC2M 4NR.
Tel. 01-283 3391
@ Circle No. 182
PRACTICAL COMPUTING September 1979
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@ Circie No. 183
PRACTICAL COMPUTING. . September 1979
86
How to build your own |
THE ADDITION of joysticks to games prog-
rams can be very rewarding. They speed
the action and allow the players to con-
centrate on the screen instead of the
keyboard. The players can also sit away
from the computer and avoid getting in
each other's way. Fights are therefore less
likely. Drawing on the screen becomes
easy.
For most applications, computer game
joysticks need not be similar to those
used by radio-control enthusiasts. In their
case, precise control is needed and is
obtained usually by the use of two vari-
able potentiometers set at right angles to
each other.
The resistance of each potentiometer
alters with the position of the ‘stick’ and
an infinite number of positions and com-
binations is possible. To enable this type
of control to be used on a computer we
should need to convert the output from
analogue to digital form. That would
involve the use of external circuits and
more complicated programs.
The majority of games and drawing
programs require information only as to
whether the cursor — man, tank and the
like—is to move up/down/right/left/or to
stay still. The joystick has to be able,
therefore to output only five states, each
of which is absolute — either yes or no.
That is a task suited ideally to a simple
switch. We will reed four per stick. With
those four switches we can cater also for
diagonal movements and the firing of
guns. If two joysticks are used together, it
is essential that they do no interference
to each other.
The ideas for joysticks offered here
Diagram |: Simple. push-switch arrangement.
Digital ground:
oe i
l |
Wire ag
connections te if
:* 1+ UP
Push =!
switches
LEFT DOWN
c-
PRACTICAL COMPUTING September 1979
To computer port
were formulated with the Pet in mind and
software will be given for Pet users.
There is no reason why users of other
machines should not adapt the methods
to their own use. So long as an eight-bit
parallel input port is provided on the
computer, only the address will have to
be changed.
The Pet possesses a very versatile user
port through which data can be read or
output. The port is provided with sophis-
ticated handshake lines but we need only
the eight bit lines, PAO-PA7. We do not
David Annal describes how easy it is to make up
joysticks to input graphical commands.
need to program these lines to be used as |
inputs, since, in default of instructions to
the contrary, Pet sets them as inputs at}
switch-on.
Each bit line is set high, i.e., toa ‘1’,
unless the line is grounded when it
becomes low, i.e. a ‘O’. As soon as the
line is disconnected from ground, the bit
reverts at once to the high state. All we}
need to do to cause a bit, or several bits,
to go low is to place a push-switch bet-
ween the pin and digital earth and press |
the button. The joysticks described do
that.
Push switches
The simplest device which will perform
all the tasks outlined is a small box with |
four push-buttons mounted on it. Each is
| a push-to-make type. They are connected |
as in diagram |. The push switches can be
PGES
'
{
=
RIGHT
Diagram 2: Upside-down box.
JoystickSaaaaam
used directly for the main movements as
shown but, in addition, diagonals can- be|
utilised by pressing two switches at the
same time e.g., Up and Right to move
diagonally in that direction. Any combi-
nation can be used for other instructions
but the method becomes clumsy if three
pushes have to be pressed at the same,
time. |
A refinement is to turn over the box
and use it on a hard surface, such as a
table. Miniature push-buttons with fairly
large Operating movements work best in
that way. The position of the left and
right buttons must, of course, be
reversed. |
In use, the box is covered by the palm
of the hand and moved as a whole with a
downward tilting motion towards the |
direction required. The box acts as a joys-
tick. Diagonals can be obtained by pres-
sing down a corner so that two neigh-
bouring pushes will close at the same
time.
Other combinations of two or three are
impossible but that with all four buttons |
closed can be used easily by pressing the
box hard down on to the table. This could
be made to fire a gun. It may be necessary |
to place small pieces of felt on the tips of |
each push-button to take-up any differ-
ences in Operating movement when all
buttons are pressed at once.
(continued on next page)
87
Miniature microswitch
with wheel lever
4
as
ss
Diagram 3: Arrangement of
microswitches.
Moving stick
A true compact joystick which works well
and uses only easily-available compo-
nents can be made with miniature mic-
roswitches. They must be the type oper-
ated by levers. They can be bought in lots
of 10 from several electronic shops and
are inexpensive. The switches are
mounted as shown in diagrams 3 and 4.
The operating levers bear on a washer
of about %in. diameter. The boit hole
must be larger then the diameter of the
bolt by about Yin. so that all-round
movement is possible. Another washer
and a knob, or terminal, is placed above
the panel as shown. The switches can
then be used to detect movement in the
four main directions and also diagonally,
when two switches will operate. The
natural spring action of the levers returns
the knob to the neutral position when the
hand is removed.
This joystick works smoothly and 1
think it has a nicer ‘fee? than those men-
tioned earlier. The disadvantage, how-
ever, is that no other easily-accessible
codes are available to operate other func-
tions. This can be overcome by using one
or two extra push-switches with two
make poles. They are connected across.a
pair of opposite switches as shown ih
diagrams 5 and 6. This then forms a com-
pact box with satisfying, positive actions.
Other possibilities
Sliding bars Many commercial joystick:
use the principle of a contro] rod moving
in slots of two actuating levers at right
angles to each other (diagram 7). Setting
them up to operate switches is not easy
without workshop facilities. Also, some
form of centralising device must be pro-
vided but it could be two elastic bands.
Magnets can be made to operate sets of
reed switches. Such a method can easily
be made to operate the four cardinal
switches but diagonals are difficult. Four
more double-pole reed switches could be
added at each diagonal.
Direct switching. The control lever can
be made to contact spring metal slips
‘situated round the eight directions
required. Centring will have to be pro-
vided. This method seems easiest of all
but it is difficult to obtain positive switch-
ing and prevent double movements.
Software
We will continue ourselves to reading
the joystick positions in Basic. This is fast
Operating knob
Top Washer
\ Microswitch with
\ roller whéel
Thick washer
Diagram 4: Construction of
operating button.
enough for most applications and, in any
case, the whole routine is very short.
The eight input bits are divided into
two lots of four. The higher four are used
to read the left-hand joystick, and the
lower four the right. The possible combi-
nations of the two sides are shown in the
table 1. ‘O” shows an earthed line. For
TABLE |
AND 240
Gives
Value of
LEFT JOYSTICK
128 64 32 16
Comore Ce = C= = =
SCmoocoe = OFC ==
Cewmreeeeow res C=
(—— ed)
1
1
1
1
0
1
1
0
1
0
0
0
RIGHT JOYSTICK and 15
PA7 PA6 PAS PA4 PA3 PA2 PAI PAO Gives
MEANING
NEUTRAL
UP
‘RIGHT
DOWN
LEFT
UP & RT
Special
UP & LFT
DOWN & R
Special
DOWN &L
“FIRE”
(see text)
Comore Cre = CH= ab
Cm OSCE SB CF ae Se mh
Cm =emoco= == So = =
Tonpun Extra push switches
mpurbert if required
Diagram 5: Wiring for extra
control buttons.
the reason given, combinations of three
are not included. The state of all four
lines grounded is shown, as it can be used
in the upside-down box.
The numerical value given by the com-
bination of inputs from one joystick is
shown, together with the decoded func-
tion to which it is put. There is no set
convention and those used are my own
choice. The -alue is obtained, in the case
of the lower ¥2 byte, by ANDing with 15
(i.e. 8+4+2+1), and in the higher by
ANDing with 240 (i.e.
128+64+32+16). By dividing the value
of the copper 42 byte by 16, a number
corresponding to the lower half is given.
If this is done, the same subroutine can be
used to jnterpret both sets.of figures.
The program required to decode the
switches will depend on the configura-
tion of the input port. The one given will
work only on a Pet. Numerous IF THEN
statements have been avoided by the use
of an array with 15 subscripts. This leads
to a very compact program.
In the demonstration program, the
alray contains statements which give the
joystick position in words. In a games
program they would be replaced by
instructions relating to the movement of
the cursor or tank. The Pet user port
input is situated at dec.59471, hence the
use of this number in the PEEK state-
ments.
Movement
The Pet video RAM is located between
32768 and 33767. The former is the top
left position, the latter the bottom right.
The symbol for the ‘man’ required 1s first
poked on to the screen in the desired pos-
ition, using a number between those
given above. Subsequent movement is
made by adding a number, which
depends on the joystick position, to the
old value and then poking the result on to
the screen to show the new position.
Before doing so, the old position could |.
be poked out with a blank (,32) if a ‘trail’
is not required. For drawing; or trapping
games, this would not be necessary and
the old position is left showing.
PRACTICAL COMPUTING September 1979
The SATA statements are altered to
give the number needed to be added to
the old screen position to give the new
one. So, for instance, 40 will be inserted
instead of Down. This is because there
are 40 characters per line on the Pet.
Other substitutions would be made as in
diagram 9. It may be necessary to ensure
that a man cannot be moved off the sides
or top and bottom. This can be done eas-
ily with extra lines and is not detailed
here.
Program listing
; Note that we have connected the
switches as per table 2. Note also the nul
strings used to cover unused com-
binations in the data statements. Each
Diagram 8.
Operating
Magnet mounted on
control column
fi
Reed switch
Magnet
PRACTICAL COMPUTING September 1979
Diagram 6: Finished joystick with extra controls.
Diagram 7.
data statement must be a total of 12
characters long to ensure erasure of the
previous position.
100 REM JOYSTICK TEST PROGRAM
110 DIM J$(15)
120 FOR =e SH aa J$(P); NEXT
130 PRINT ‘*cir.cdx
140 & PEEK (Soerly AND 15: PRINT TAB (25); J$
(P); °
150 P+ (PEEK (59471) AND 240y16: PRINT TAB (2);
P):*
160 GOTO 140
1000 DAT ‘BANG! = °.0.0." DOWN & LEFT
’* SPECIAL POSN” “UP & LEFT”
1010 DATA *LEFT’O,*DOWN & RIGHT", “SPECIL
POSN™,* DOWN”
1020 DATA * “UP & RIGHT ~
-NEUTRA
+ RIGHT "UP
Line 130 1s — Print clear screen followed by 12 cursor
downs. cu in lines 140 & 150 is cursor up.
Joysticks a
[| Control column
uf
Control column
mS
'
Slider bars
Rubber bands
Centring device
| TABLE 2
Switch Connections
LEFT RIGHT
UP PA 4 PA 0
RIGHT PA 5 PA 1
DOWN PA 6 PA 2
LEFT PA 7 PA 3
The author would be most interested to|
hear of any other home made joystick
mechanics.
Diagram 9: Portion of Pet screen
to show relationship of
surrounding positions.
Present
position
89
90
ONFERENCE JUNE
NCC Street scene with the obligatory New York Yellow Cab.
NCC aimed to impress
small business buyer
IF YOU are American, and if you sell, buy,
yearn for or just read about computers,
the chances are that you were at the
National Computer Conference.
The NCC is the world’s biggest annual
computer trade fair and every year it gets
bigger. The 1979 model featured some
500 exhibitors who paid for 1,700 exhibi-
tion spaces and talked to at least 70,000
visitors in the four days of the show. On
the morning of day one, the queue was
taking more than three hours to move in.
Fortunately your correspondent had the
magical pin-on Press pass which gained
instant admission to a Press room well
equipped with Budweiser and Diet Pepsi.
The show is too big to hold in a single
Olympia-style cattle market and it
sprawled across several of the expense-
account hotels in the centre of New York
City. That meant journalists trekking
through corridors of distressed Italian
cornices and generally fake baroque join-
ery — hotel designers in New York seem
to have impressively poor taste.
One mouse cheated
The Sheraton Centre did not seem to
be in that league, though, and in its well-
appointed basement were the 92 booths
of the personal computing ‘festival’.
Elsewhere in the hotel was the associated
personal computing conference, and the
finals of the Amazing Micro-Mouse Maze
Contest.
The aim was to design a mouse-like
robot which would negotiate a maze
course; and since the winner would
receive $1,000, there was a good field.
Most mice missed the finals and some
which did not preferred to turn and
retreat halfway through their run. One
seemed to us to cheat — it kept turning
left until it found a path to the end.
“Heuristics is dead,” said the designer.
The winner and the runner-up were
both from a specialist research organisa-
tion, the Battelle Institute. Moonlight
Flash earned the $1,000; Moonlight
Express was second.
The exhibitors in the cellar generally
outshone their expensive and glossy big-
computer competitors in the main exhibi-
tion area. Apple Computers had a very
impressive presentation in a suite away
from the rest of the personal computers,
emphasising discs and business software
— as well as its own general corporate
standing.
The aim, at least for the NCC, was to
impress the small business buyer. Most
new Apple products on show in New
York were software, U.S.-orientated bus-
iness packages and the new Pascal, which
looked very good.
Another very interesting Pascal prom-
otion was in the main NCC show. Pertec
showed its Pascal Blaiser — after Blaise
Pascal. It combines the Western Digital
Pascal Microengine — a micro with
Pascal on ROM — with two Pertec
floppies in the cabinet.
Commodore also aimed hard at
businessmen and sited its stand in the
main exhibition. Tandy stayed with the
personal computer fraternity, though,
with a large booth in the Sheraton. It was
worth it; the new TRS-80 Model I] is
most impressive.
Like the existing TRS-80, Model ll
uses the Z-80 micro, but running it rather
taster, at 4MHz. Built into the screen is
one full-size double-density floppy disc
(512KB). An expansion unit supports up
to three more of those discs.
The keyboard is new and has a numeric
pad as well as two user-programmable
function keys. Unlike the Model 1, the
Model I] does not have Basic resident in
ROM. It loads the operating system
immediately and Basic from disc when
power is turned on. Tandy says that is to
allow the use of other languages without
having ROM space go to waste; lan-
guages available include Fortran.
Five business software packages were |
unveiled with it, all for the U.S., priced
between $150 and $400.
We were told that the U.K. wouldn't
see Model 1] for **a few months’. In the |
States the basic Mode] II system, with |
one disc drive and 32K of RAM, is priced
at $3,450. A full-blown system with 64K,
three drives, a line printer, and a worksta- |
tion desk sells for $7,998.
Impressive
At the other end of the scale was
another good-looking product. The New
York-based Computer Systems Store has
a relational database manager for micros,
called REINS, which runs on a 64KB
Pertec/Altair 300. The presentations
were impressive.
Elsewhere on the floor there was much
to try but little innovation. The likes of
Cromemco and Compucolor were pulling
the crowds but so were the many compu-
ter stores shouting their many wares.
Several established software vendors
were there. Micropro had its word pro-
cessor on two stands; GRT and Personal
Software continued to look very profes-
sional with games and graphics; Lifeboat
was listing ‘“*the latest and best” in 8080
and Z-80 packages from several sources,
including Micropro.
PRACTICAL COMPUTING September 1979
Exidy had a new and neat screen-plus-
floppy disc organisation and was at last
demonstrating the plug-in ROM-PAC
word processor — much-delayed but
apparently fast and effective in operation.
There were fewer dramatic advances
among peripherals than one might have
expected. The cheap rigid disc is not yet
with us and there seems little real oppor-
tunity to get away from screen and
keyboard for communication between
people and electrons.
Things are happening on the printer
front, though, with falling prices on small
matrix printers proclaimed by several
vendors. Integral Data Systems had its
Brighter Writer range there — more than
5,000 sales to date — but also showed a
new printer called Paper Tiger. Aimed at
The new Exidy screen and
mini terminal. What you can’t see
— the ROM-PAC word processor
inside.
bulk buyers, it offers 80 to 132 columns,
full upper- and lower-case, tractor feed
and a quantity price of $995 each.
In general, though, the personal com-
puter side of the NCC was not a show for
hobbyists or computer freaks. Most of the
stallholders to whom we spoke were look-
ing for the proprietors of small businesses
or for people from systems builders and
computer shops who would buy in large
quantities.
The talks at the personal computing
conference covered some good ground
and if you have the opportunity to buy a
copy of the papers, do so. Sadly you will
not acquire the impressive evangelical
favour of Ted Neison’s keynote speech —
computers won't save the world, but they
might make it a more pleasant place in
which to live. On second thoughts,
perhaps they will save the world at that.
Why Petsoft went to the NCC
AT PETSOFT we have been developing
software for the Commodore dual mini-
floppy. Now we were starting work on
material to run on the Compu/Think
device — hence my visit.
The Micromax has an enormous 105K
internal memory plus up to 2°4 mega-
bytes of on-line disc storage, substantially
more than on other micro systems. The
double-density dual drive stores or
retrieves its 2-4 megabytes at 15,000
characters per second.
Of particular interest is the full-screen
data-entry and editing capability. The
screen can be divided into several distinct
and separate application areas, each with
its Own separate data entry and display.
The screen is a 12in. integral CRT
monitor with a format of 64 characters by
PRACTICAL COMPUTING September 1979
A runner in the Amazing Micro-Mouse Maze contest.
30 lines, giving a total of 1,920 characters
per screen.
The internal memory consists of a
108,544-character semiconductor mem-
ory allocated to resident system software,
Microsoft Basic with string capability and
extended precision floating point. There
is also a complete disc-operating system
by Julian Allason
which includes random access datafiles.
Space is also allocated to video memory,
disc directories and disc data buffers.
Other resident features include the
high-resolution graphics commands, a
FIFTH language micro-programmed
interpreter and a complete machine lan-
guage monitor with Tiny Assembler, dis-
assembler, dump facility and a debugging
aid with break-point capability.
Some of the commands for the Disc
Extended Basic are entered directly from
the video/keyboard terminal. Others can
be coded in Basic to perform disc-file
input/output. Sequential and random
access are supported on the disc drives, as
well as the program and data files.
Visitors to the show particularly liked
New York report =
the high-resolution graphics, which are |
very sharp indeed.
The central processor-is a hybrid 6502 |
which runs at 2MHz and executes all of
the 6502 instructions, plus 64 additional
user-definable instructions. At initialisa-
tion the instructions are microprogram-
med to execute 64 instructions of the |
language. |
FIFTH universal machine
Despite the pun, FIFTH appears to be a
useful combination of FORTH and
Pascal. Whether the world is ready for yet
another computer language is another
matter.
The user may also microprogram the
64 instructions to perform Pascal opera-
tions, FORTH operations, or to emulate
any other computer whether on or off the.
drawing board.
Compu/Think is offering a database |
called Page Mate, which is a set of five
programs designed to perform most of
the common data manipulation functions
for the computer user without requiring
him to resort to programming.
1 suspect that in developing what is
arguably the most advanced microcom-
puter yet, Compu/Think has blazed a trail
which other manufacturers will be
obliged to follow.
At the time of writing, the Micromax
was on sale in the States at $4,495 for the
model with 800K of external memory
and $5,995 with 2-4 megabytes of on-
line disc storage. It should be available in
the U.K. by November. A specification is
available from MicroAct Ltd, 5 Vicarage
Road, Edgbaston, Birmingham,
B15 3ES. iM]
91
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Keeps Abacus running smoothly
Keeping things running smoothly
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Tel: (0462) 51511 Telex: 826649
@ Circle No.. 184
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Supplied by - Factor One Computers
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@ Circle No. 185
92 PRACTICAL COMPUTING September 1979
= a rr 20) 0
Lien times
DAVID LIEN visited the office recently. So
who’s David Lien? Well, he is one of the
three original designers of the TRS-80.
He wrote the excellent Level I handbook;
and his company, Compusoft Publishing,
was responsible for the Basic Handbook
we reviewed so enthusiastically in May.
David has just arranged an exclusive
U.K. distributor for the handbook, the
Rostronics Computer Centre, 118
Wandsworth High Street, London SW18,
telephone 01-870 4805. The U.K. price
will be £10.
Other works are due from the Lien
stable later this year, and we like the
sound of two of them. Learning Level Il
will be a Compusoft-produced equi-
valent of the Level Users/Learners’ Man-
ual, written in the same style and by the
same author.
How about Controlling the world with
your TRS-80? This promises to teach you
how to use your computer to water the
lawn, monitor a home security system,
control an electric train, dial the tele-
phone and “endless other applications”.
We'll keep you posted.
Birthdays problem
HOW MANY people do you have to cram
into the same room before it becomes
Statistically likely that two of them have
birthdays on the same day? John Dod-
ridge contributes this program to find
out:
10
20
30
295
ae
T “DO YOU WANT WEEKDAY (ENTER
R BIRTHDATE (ENTER ‘364')?”
D
.
40
50
60
70
80
90
100 P=1-Q
110 PRINT “WITH”; “PEOPLE IN THE ROOM
THE CHANCE IS"; P
120 IF P=1 THEN END
130 GOTO 70
Z3
ge
tu nn
ae
O2eazZz>
Zeo
i
fe)
x
Zz
>
Working out the chances of two people
in the room having the same day or date
of birth is a classical one but the program
proves to be simple, because of the
repetitious nature of the calculation used
to find the solution.
The proof hinges on the use of the
probability theorem P+Q=1, where P is
the chance of an event happening and +
is the chance of it not happening. The
re-arrangement of the formula gives
P=1—Q and it is this which is used to
reach the answer via the complement.
Entering ‘7’ finds the number of people
in the room needed for two to have the
same day of birth in the week; for birth-
dates the program takes the number of
days of the year as 364, but 365 gives
only a slightly different answer.
It is surprising to find that only 23 peo-
ple are needed in the room for the chance
PRACTICAL COMPUTING September 1979
TANDY FORUM is devoted to the Tandy TRS-80. We will be using It
to pass on news about the TRS-80 and its supplier and product
announcements from Tandy and other vendors of compatible
equipment. Above all, these are pages for users, and would-be
users, of this personal computer. We want you to send tips,
queries, moans and comments, and we want this page to become
a market-place for TRS-80 information.
of the same birthday to be greater than
50/50, or odds-on. The last line reads:
364 X 363 X 362 x... X 343 x 342
Q= 364”
and so P = -508275.
= +491725
Tiddley winks
THIS ONE COMES from Stephen Toop.
Although the game is very simple, it illus-
trates the parabola function well.
The function, which is given y=x’, can
be plotted easily, but because of the large
variation between the values of x and y,
formulae, but we plot z,y rather than x,y
so it will all fit on to the screen. L is the
variable controlling the length of the plot.
5 REM *TIDDLEY WINKS: PROGRAMMER
$.G.TOOP: 1/3/79*
10 CLS
15. PRINT AT 470 “*TIDDLEYWINKS*”
20 PRINT AT 904, “JUST SET THE LENGTH AND
TRY TO FILL THE HOLE.”
25 FOR A=O TO 800
30 NEXTA
35 LETG=0
40 LET P=RND(110)+10
45 CLS
50 PRINT AT 960, "0";
55 SET(1,42)
60 FOR X=1 TO 127
65 SET(X,43)
70. NEXT X:LET X=127
75 PRINT AT 1020,"100";
80 FOR X=42 TO 7 STEP-1
85 SET(X,Y)
90 NEXT Y
95 RESET (P,43):RESET (P+ 1,43)
105 PRINT AT O, “SET LENGTH”
110 INPUTC
115 IF L<0 THEN 105
120 GOSUB 1000
140 LET Z=Z-L/19
150 IF (INT(Z)=P)+(INT(Z)=P+1) THEN 220
160 LET G=G+1
165 PRINT AT 14,"
170 IF G<3 THEN 105
180 PRINT AT O,"GIVE UP BUSTER, YOU'RE
HOPELESS!”
190 FOR A=1 TO 1000:NEXT A
210 GOTO 35
220 SET(Z,Y+1)
225 PRINT AT O," WELL DONE YOU GOT IT
IN";G+1-".
230 GOTO 190
Parabola subroutine
1000
1010
1020
1030
1040
1050
1060
1070
1080
2000
LET X=-6
LET Z=X+7
LET Y=X*X+6
IF Z>=127 THEN 2000
SET(Z,Y)
LET Z=Z+L/19
LET X=X+0°5
IF X<>6:5 THEN 1020
RETURN
PRINT AT O, “OVER SHOT A BIT DIDN'T
WE MAC?";
2010 GOTO 190
we must use different scales on the axes| Emcore
to make the graph as large as possible and
sO ensure the greatest possible accuracy
of the results.
To use the TRS-80 SET/RESET func-
tions we must start the plot at x+n —
where x is negative and is a number that
when added to x makes x a positive
number.
In the program the function is used to
plot the trajectory of the tiddleywink.
The height and length of the plot are cal-
culated easily, although changing one will
result in a change of the other.
The parabola subroutine has a number
of variables for such a simple function.
This was necessary for total control. x and
y are exactly the same as they are in the
T&V JOHNSON telephoned to say that our
enthusiasm for Percom add-on discs can
be qualified by their availability in this
country; TVJ has them ex-stock from
about £350. You will need the expansion
interface and controller, which TVJ can
also offer at prices better than Tandy.
If you want to consider other alter-
natives to Tandy, TVJ also has plug-
compatible Micropolis and Shugart
drives.
Enthusiasm
THE GENERAL impression put forward in
Tandy Forum and in last year’s review of
the TRS-80 is that it is a vague, unre-
(continued on page 95)
93
94
ws,
a a
ib
we
M4 |
Thenc
m
etothe number one
—
He hy
agg,
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PRACTICAL COMPUTING September 1979
(continued from page 93)
liable machine. | have been using a 4K
Level II TRS-80 since October and have
been extremely pleased with it. It is a
remarkably well-thought-out product
when compared to most of the rest in its
price bracket, writes N. J. Powell, of
Yorkshire.
To set the record straight I have listed
its attributes under several headings,
which reflect the longer-term use of the
machine rather than the 24-hour,
review-type impressions.
Retail Organisation
@One-year guarantee; U.K. repair
centre; all retail outlets are repair
agents, _
@ Local retail outlets; over-the-counter
service — no long journeys or six-
month delivery delays after cashing
your cheque; all Tandy products read-
ily available and demonstrable locally.
@Full service manual available with
detailed trouble-shooting routines.
@ Software/hardware availability from
Tandy. Some of the Tandy hardware is
cut here on top
Feed
through —————->
hole
~Link here
underneath
Locate 732 on the board top.
Figure 2.
exceptionally good value; for example,
the expansion interface contains decod-
ing for an extra 32K RAM, a second
cassette interface (for a standard cas-
sette recorder), the Micropolis diskette
controller (for four drives), real time
clock, Centronics parallel printer inter-
face, bus buffering, and power supply
— all for £229.
Operational Use (Level II)
@ User-definable memory map for
machine code routines. Pet owners
please note, there’s no poking into the
second cassette buffer.
@ Z-80 processor for running machine
code programs.
@ Superb line-editing and trace facilities
for program debugging.
@ Very compact code storage — 4K bytes
goes a long way on a Level II.
@ Very good output format control, and
addressable PRINT statements — not
a plethora of tab and cursor statements
as with Pet.
@ X-Y addressable graphic locations for
plotting low resolution (6,144 points)
graphics, which can be mixed with text
PRACTICAL COMPUTING § September 1979
Disconnect pin 2 of 766 from line R4 and
connect to line RB.
Figure |.
on the screen. (Apple users, please
note). High-resolution graphics could
be written to a suitable plotter or
printer by a machine-code subroutine.
High-resolution plots on a screen are
unlikely to be of much use other than
as an expensive doodlemaster.
@ Level I is better than most Tiny Basics
as it supports floating point arithmetic.
Hardware design
@ Works with ASCII internally, including
lower-case letters —- unlike PET, the
TRS-80 doesn’t need an intelligent
printer.
@Uses cheap dynamic RAMs which
make it easily and cheaply upgradable.
@ Has a proper keyboard which can be
used by the nimble-fingered for prog-
ram entry, word processing, and the
like.
@ Uses a standard cassette recorder.
@ Lower-case letters are available to a
printer without modification, the video
is modified easily to display lower-case.
@ Standard video out, modified easily to
50Hz if required.
@Compact, keyboard, power supply,
Tandy forum am
cassette, and modulator fit easily into a
briefcase.
@40-pin expansion bus with all the
required signals instead of enormous
sockets and 100-way ribbon cables — a
domestic controller circuit is given in
the technical handbook.
Reliability (over six months)
@ A dry joint in the power-on re-set was
fixed under guarantee.
@ Overheads and crashes occurred only if
the air vents under the keyboard unit
were covered or restricted.
@1 have had no problems with the cas-
sette — a very old Philips 3302. 1 use
Memorex MRX2 tape.
Tips
So much for the banner-waving — now
for three tips:
@ PRINT (HR$(28) converts back from
32 characters per line to 64 without
clearing the screen.
@To hook up a modulator, go for a
high-resolution unit — which means
spend £4.50 rather than £2.50 — run-
ning off +5V. Video goes to pin 4 of a
5-pin 180-degree display via about 2in.
of co-axial cable; +5 V goes to pin 1 via
2in. audio-screened lead. Both screens
go to pin 5 with the co-ax screen only
forming the common return on the
modulator. 1 use a modulator from
Computer Workshop, Manchester.
® Locking-in on a British TV will need
adjustments of the line hold (from
15,625Hz to 15,835Hz) and the frame
hold (50Hz to 60Hz). If the TV set is
an old one — without flywheel sync or
with valves — the picture is likely to be
unstable due to the presence of 50Hz
mains hum. In these cases the video
chain should be converted to 50Hz as
below. ‘
A modification for the 50Hz frame is
shown in figures 1 and 2. The video
divider chain divides the 15,835Hz line
frequency by 12, 2 and 11 to give 60Hz
(264 lines per raster). We require about
625 + 2= 312 lines per raster, dividing
by 12,2,13. This gives a frame frequency
of 50 to 75Hz. This should enable most
TVs to lock in, but with valve sets there
may be some pronounced ham bars at
1: 5Hz. The + 13 modification is accom-
plished easily.
If hum bars still persist a frame fre-
quency of 49:95Hz can be obtained by |
allowing 317 lines per frame. This
requires an additional three input AND
gate wired as in figure 3.
After either of these modifications the
display should be centred with R20/R21.{
95
rere at last!
Super software from the world’s leading microsoftware supplier.
Oo
oO
DIGITAL RESEARCH
CP/M* FDOS — Diskette Operating System complete with
Text Editor, Assembler, Debugger, File Manager and system
utilities. Available for wide variety of disk systems including
North Star. Helios {!, Micropolis, iCOM (all systems) and Altair.
Supports computers such as Sorcerer. Horizon, Sol System Ill.
Versatile. Altair 8800, COMPAL-80, DYNABYTE DB8/2, and
iCOM Attache. Specify desired configuration : £75/£15
MAC — 8080 Macro Assembler. Full Intel’ macro definitions.
Pseudo Ops include RPC, IRP, REPT, TITLE, PAGE, and
MACLIB. Z-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 utilities. 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 printing of
data from disk while user executes another program from the
console £30/£1
MICROSOFT
Disk Extended BASIC — Version 5, ANSI compatible with
long variable names, WHILE/WEND, biliahinss: variable length
file records j ..., £155/£15
BASIC Compiler — Language compatible with Version 5
Microsoft interpreter and 3-10 times faster execution. Pro-
duces standard Microsoft relocatable binary output. Includes
Macro-80. Also linkable to FORTRAN-80 or COBOL-80 code
modules . £195/£15
FORTRAN-80 — ANSI ‘66 (except for COMPLEX) plus
many extensions. Includes relocatable object complier, linking
loader, library with manage": Also includes MACRO-80 (see
below) .£205/£15
COBOL-80 — ANSI ‘74 Relocatable object outpul. 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. Relocatable linkable output. Loader,
= Manager and Cross Reference List wae
EDIT-80 - Very tasi 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)
Z-TEL — Text editing language. Expression evaluation itera-
tion and conditional branching ability. Registers available for
text and commands. Macro command ae can be saved on
disk for re-use oe ..,, £40/£12
ASM Macro Assembler — Mnemonics per Intel with Z-80 ex-
tensions. Macro capabilities with absolute Intel hex or relocat-
able linkable output modules. New version 3 with added
features .£40/£12
LINKER -— Link-edits and loads ASM modules . £40/£12
Z-BUG debugger — Trace, break-point tester. es dec-
imal, octal and hex modes. Dissassembler to ASM mnemonic
set. Emulation technique permits full tracing and break-point
support fiattewte OIC he igeo comes 6 acd Gernercenin o- .£45/£12
TOP Text Output Processor — Creates page-numbered, jus-
tified documents from source text files .£40/£12
‘CP Misa trade name of Digilal Research
*Z80 1s a trademark of Zilog. Inc.
EFFECTIVE 1 AUGUST 1979.
SS
Oo
O
O
O
a
A4 package includes Z-TEL, ASM, LINKER. Z-BUG. TOP
. £155/£30
EIDOS SYSTEMS
KISS — Keyed Index Sequential Search. Offers complete
Multi-Keyed Index Sequential and Direct Access file 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 tf — Above available as absolute program onl
£105/£1
Super-Sort t}— As {| without SELECT/EXCLUDE
, ... £75/£15
1 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 full
screen editor for users with serial addressable-cursor terminal
: . £75/£15
Word-Star — Menu driven visual word processing sys-
tem for use with standard terminals. Text formatting performed
on screen. Facilities for text paginate. page number, justify,
center. underscore and PRINT. Edit facilities include global
search and replace, read/write to other text files, block move.
etc. Requires CRT terminal with addressable cursor position-
ing €255/£15
SOFTWARE SYSTEMS
CBASIC-2 Disk Extended BASIC — Non-interactlve BASIC
wlth pseudo-code compiler and runtime interpreter. Supports
full file control, chaining, integer and extended precision var-
iables etc. .£75/£10
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, eeyrel log, Eales and bank bye oe CBASIC-2
.., £475/£15
COMPANY SALES — Performs sales accounting tunction.
Controls payments of invoices and prints sales ledger and aged
debtors report. Suitable for any accounting period. Comprehen-
sive VAT control and iat ane 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
NAD system. Requires CBASIC-2. .£425/£15
NAD—Complete control of all your names & addresses including
suppliers, clients, enquiries etc. Assign your own coding system
and select all output via the report generator. Will print anything
from mailing labels to directories. Requires CBASIC-2.
.£225/£12
PRACTICAL COMPUTING September 1979
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
oe |
STRUCTURED SYSTEMS GROUP
OC) QSORT — Fast sort/merge program for files with fixed record
length, variable field length information. Up to five ascending or
descendin: 4 | keys. Full back-up of input files created. Parameter
file created, optionally with interactive program which requires
CBASIC. Parameter file may be generated with CP/M assem-
Blerutilitiyrs seas. as... . tae - ol eee £50/£12
GRAHAM.-DORIAN SOFTWARE SYSTEMS
OC 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
OC) 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. - Supeted in source
OBES... Tice ee. te ee itis . £300/£25
O) CASH. REGISTER — Maintains files on daily sales. Files
data by sales person and item. Tracks sales, overrings, re-
funds, payouts and total net os ‘Requires CBASIC.
Supplied in source code 3 . £300/£25
MICRO FOCUS
0) CIS COBOL — Version 3 is ANSI 74 subset with extensions
which offer powerful interactive screen formatting and built in
cursor control. Version 4 additionally offers full level 1 ANSI for
Nucleus, Table Handling, Sequential Relative and Indexed I/O,
Inter- oak pa Communication and Library
Version 3, £295/£25
. Version 4, £395/€25
0 FORMS — Interactive utility to create CIS COBOL source
code to perform CRT screen honey in application 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
O tiny C — Interactive interpretive system for teaching struc-
tured programming techniques, Manual includes full source
NSTINGS: Fa%........: 8, arpapeeene teams ne . £45/£30
C) € Compiler — Supports most major features of language. in-
oan tructures, Arrays, Pointers, recursive function evalu-
ation, linkable ‘with library to 8080 binary output. Lacks data
initialization, long & float type and static & register class speci-
fiers. Documentation includes “C” Miso remenieg Language
book by Kernighan & Ritchie ................... £65/£10
0) 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 disk file for ei LOAD,
DDT onSiPitaciitiess =. .-c..-....\ cere. : beets 50/£12
O DISTEL — Disk based disassembler to Intel 8080 or TDL/
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
QO) DISILOG — TEL to Zilog/Mostek mnemonic files.
Rufis on: Z80enlys .., aeeaer twat be cee eaten er €35/£7
Lifeboat Associates, 32 Neal Street, London WC2H 9PS, 01-379 7931 '™'The Software Supermarket is a trademark of Liteboat
PRACTICAL COMPUTING. September 1979
Lj TEXTWRITER Il — Text formatter to justity 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 hy on
other files. Ideal for contracts. manuals, etc. . £45/£3
C) WHATSIT? — Interactive data-base system using associa-
tive tags to retrieve information by subject. Hashing and ran-
dom access used for fast papense: Hedge peak
O 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 ROMable versions.
Integer Disk or Integer ROMable ............. . £165/£15
Extended Disk or Extended ROMabie . £215/£15
CO) SMAL/80 Structured Macro Assembled Language — Pack-
age of powerful general purpose text macro processor and
SMAL structured language compiler. SMAL is an assembler
Bb on with 1F-TH LSE, LOOP-REPEAT- bie DO-
BEGIN-END constructs ......... _, £40/£10
©) Selector Il — 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
OC) Selector ti! — Multi (i.e., up to 24) Key version of Selector Il.
Comes with applications programs including Sales Activity, in-
ventory, Payables, Receivables, Check ig Expenses,
Appointments, and Client/Patient. Reales Bree a auppied
INISGDICEICOGE! a. falas acs ets. £12
Enhanced version for CBASIC-2 ‘ “Cece
QO) 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
(oie, 2. foe eee . €£125/£7
O Filppy Disk Kit — Wee ie and instructions to modify sin-
gie sided 5%" is el for use of second side in singly a
GIVES! ans eeMGE Soar +< Mane» 6
Orders must specity disk
type and format, e.g. North
Star Horizon singledensity.
Add VAT to orders for soft-
ware (not manuals alone)
Add 50p per item postage
and packing (minimum £1)
All orders must be prepaid
(except COD or credit
card). Make cheques POs
‘etc. payable to 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
on one system only.
Associates
RerirplRereisabbine
@ Circle No. 187
97
These pages represent an independent collection of news |
and views for owners of the Commodore Pet. If you wish to
contact Pet Corner, send articles or ideas directly to us. We
are not connected with Commodore or with the official
Commodore-run Pet Users’ Club, though we wish it well.
We give space to Mike Lake, of the Independent Pet Users’
Group (IPUG).
SEVERAL members of IPUG have ex-
pressed interest in using X-Y plotters
with their Pets, writes IPUG secretary
Mike Lake. Investigation has turned up
the following:
Sylvanhill Laboratories Inc, of Box
646, Pittsburg, Kansas 66762, offers plot-
ters in assembled and kit form at sizes
ranging from llin. X 17in. to 22in. x
17in. at prices from $795 to $1,300.
Postage is about 12 percent of cost.
Sintrom Electronics Ltd, Arkwright
Road, Reading, Berkshire, is the U.K. dis-
tributor for the HIPLOT X-Y plotter,
Jin. X 10in., at £656 and the HIPAD
digitiser at £521.
District Computing, 174 Ifield Road,
London, is the agent for the TALOS
Paper
THE APPEAL for cheap Stationery for the
PR40 printer produced a letter from
Rockcliffe Brothers, of 2 Rumford
Street, Liverpool, L2 8SZ. The company
is offering 10 PR40 rolls at £6, 10 C15
cassettes at £3:99, and 10 C60s at £4:99.
All prices include VAT and postage, and
there is an additional 10 percent discount
if you are in IPUG member.
Rockcliffe is also seeking a supplier of
cheap paper for the Teletype 43; if you
know of a source please contact the com-
pany.
Memory locations for ROM upgrade on PET computers
Conversion
IF YOU are converting any programs from
the old ROMS on the 8K Pet so that they
will run on the new ROMS, then the table
provided is vital. Many programs make
use of locations in the first 1K of Pet
memory and this has been changed com-
pletely in the new machines. The old and
new locations — and meanings — are
given in the table.
Thanks to Roger Gentry and Barry
Miles of IPUG for their efforts in pro-
ducing the list; they were helped con-
siderably by Commodore.
Jim Butterfield, Toronto
range of digitisers which sell for around 0000-0002 0-2 USR Jump instruction
$450 in the US. 0003 3 Search character
0004 * & Sean~between-quotes flag
5 oeoe ; ou eo buffer pointer; # subscripts
r r efault DIM flag
eed prog ae Mendel Road 0007 ? Type: FF=string, 00=numeric
BETOS: SVSeENS; anslie oad, 0008 8 Type: 80=integer, 00=floating point
Nottingham, has produced a program 0009 9 DATA scan flag: LIST quote flag; memory flag
aimed at farmers with animal feed prob- | | 0004 10 Subscript flag: FNx flag
000B 11
000c ie
000D 13
O=input; 64=get; 152=read
ATN sign flag; comparison evaluation flag
input ie | suppress output if negative
lems. The program allows the user to
define the nutritional requirements of the
animals — depending on yield and weight conn — a is esiens : ) aseaee aot ae he nen )
ss sea = = asic integer address or , etc
for cattle ; and also the characteristics of 0013 19 Temporary string descriptor stack pointer
up to 15 kinds of possible feeds. 0014-0015 20-21 Last temporary string vector
The program then uses a linear tech- hehe Pg Adi! of ae rt strings
: A } = - ointer for number transfer
nique to produce the cheapest possible 0021-0022 33-34 ike, nuritee gudinkee
food mix to meet the needs of the animals 0023-0027 35-39 Product staging area for multiplication |
and any other constraints the farmer bea U4 pela ee ee ee ;
; : “ 002A-00 2-43 ointer: End-of-Basic, Start-of-Variables
might include, such as ““I want to use aS || 992¢-902D 44-45 Pointer: End-of-Variables, Start-of-Arrays
much silage as possible”. 002E-002F 46-47 Pointer: End-of-Arrays
The program outputs to the screen 0030-0031 pe rl Bottom-of-Strings (moving down)
F in 6 0032-0033 0-51 Utility string pointer
and/or a printer and runs in 8K. Betos || 90319935 2-83 Pointer: Limit of Basic Memory
offers it complete with 8K Pet and PR40 0036-0037 54-55 Currin Genesee bla mewhiitinar
‘printer for about £950. The program is 0038-0039 56-57 er tee Basic line number ,
; 003A-0033 58-59 ointer to Basic statement (for CONT
somes Paliereteny 003C-003D 60-61 Line number, current DATA line
003E-003F 62-63 Pointer to current DATA item
Challenge hae ga ia 5 Input vector
0042-0043 -67 Current variable name
a Chess Club secretary was quoted 0044-0045 68-69 Current variable address
' in a local newspaper as saying that “‘mic- 004620047 20-71 Variable pointer for FOR/NEXT
rocomputers were just chess-playing pt ck Pi Rie iater Fp einige save
” ; mparison symbol a a
Daleks , and suddenly found the club 004Bep REC 75-76 Wet iaerie srk. aed
’ being challenged to pit its skills against oo&D-AYO 50 77-80 Work area; garbage yardstick
six Pets. 0051-0653 ae Jump Miche for functions
The challenge was from David Fabri, a 00 54-00 58 84-88 Misc numeric storage area
: ¥ 0059-005D 89- Mise numeric storage area
tutor at the local further education col- fd he de moe Accumulator#11 EM, MM, M,S .
lege, who set up the machines with the 0064 100 Series evaluation constant pointer
Microchess-2 program, written by Peter || 067 904, 93 4 ae as prafagetien wort
Jennings, and which finished fourth in the 006C ‘ 108 Sign comparison, primary vs. secondary
1978 World Microcomputer Chess 006D 109 low-order rounding byte for Acc#1
Championship OO6E-O06F 110-111 boli hg buffer length/Series pointer
i 0070-0087 112-135 ubrtn: Get Basic Char: 77,78=pointer
ao a was a eee but at ba 0088-008C 136-140 RND storage and work area
end of the evening, the Pets were secon 008D-0ogF 141-143 Jiffy clock for TI and TI$ (continued on page 101)
best. The humans beat them 5-1.
98 PRACTICAL COMPUTING September 1979
we're taking
the lid off the
computer
business
eet
—_
. aed
isher-woods offer a professional
service ,tailor madeto fit your personal requirements
With the help of Commodore Systems and
the PET® Computer isher-woods can offer
both the technically minded and the
business man ready made or tailored solu-
tions to most of your particular problems.
The Commodore PET® comes in 4 different
memory sizes and is priced from as little as
under £500 (ex. VAT) for the 4K version. We
can supply 8, 16, and 32K versions
from stock, fully tested and
guaranteed. Floppies and printers are
on order.
If yaPhave a PET® or are considering buy-
ing ohe then we can look after it for you. We
give a fixed price labour charge of £20 +
parts at list price + VAT, irrespective of the
fault; just deliver to our door and we'll put it
right.
lf you just want the parts then we can supp-
ly them from our ‘“‘CHIP SHOP”. Mainten-
ance contracts are obviously
available for those who prefer ‘‘on
site’’ cover.
=
oes
A
OR Gets :
i sher-woods
Computer Systems Group
110/112 Leagrave Road. Luton Tel: (0582) 424851/39570
Sellers of PET® and other fine computer systems.
PRACTICAL COMPUTING September 1979
@ Circle No. 188
99
Introducing the DPS-1 the full IEEE S100 bus computer system from
Ithaca ‘Intersystems — the S100 experts.
FOR EDUCATION, INDUSTRY, RESEARCH and all 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.
Just look at these professional features!
* FRONT PANEL (we won't ask you to debug our hardware, but we
will give you the tools 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
IPS). hardware breakpoint on any data or address byte, repeat
instruction and many other hardware diagnostic facilities.
w 30 Amp, 8V power supply. 5 Amps on + 16v rails (all rails are
seperately fused)
* 20 slot IEEE S100 Motherboard with active termination and
shielding between bus fines
* Suitable for 6800, 6502, 8080, 8085, Z80, Z80A processors.
* Guaranteed operation at 4MHz.
The DPS1 comes as a mainframe with front panel, 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 DPSi
IEEE $100 bus.
Just add $100 Memory Boards — S100 disk controller boards — S100
110 boards — S100 video and/or graphics boards — S100 EPROM
boards
All Ithaca intersystems OEM products including K2 disk operating
system and PASCAL/Z on 8" floppy drives will run in the DPS-1.
Fully { DPS.1 with $100 4MHz 280 cpu board £695
assembled
and tested | DPS-1 less $100 4MHz 280 cpu board £645
OEM S100 boards
from the experts!
Assembled
and tested
£123.75
£146.25
8K Static RAM board (45 ons)
8K Static RAM board (25 ons)
Z80 cpu board (2MHZ)} £131.25
Z80 cpu board (4MHZ) £153.75
2708/2716 EPROM board £63.75
Prototype board (bare board) £18.75
Video display board (64x16, 128U/L Ascii) £108.75
New products from Ithaca audio!
High density graphics (1024 x §12 points)
Disk controller (up to 4 single or double sided drives)
1/0 board (serial and parallel outputs)
$100 front panel (as used in DPS1)
Analogue I/O board
£660.00
£131.25
£210.00
£245.00
£295.00
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).
Over 15,000 boards delivered worldwide
CONTACT THESE DEALERS
Inoten Ssysstheonnoss
Software for your S100 system
K2 operating system
8" disk based operating system — distributed on Shugat compatible
8" floppy disk * TED — 52 command character orientated text editor
with Macros. # PIP — File and directory handler. # ASMBLE — full
Z80 2 pass assembler. #* HDT—Hex debug tool. * QCI—Utility
overlay/command decoder. * SYSGEN—System builder. « COPY —
disk to disk file copier. *# DUP—disk duplicator. £56.25
PASCALIZ The new language tor Micros £131.25
Runs under K2 operating system.
* Compiler that produces Z80 macro
assembler code — NO NEED for slow run
time P-code interpreter. * Comes com-
“&
plete with Macro assembler. # Produces
binary object modules — small and fast.
* Modules are re-entrant and can be put
into ROM. * IMBED. TRACE and ERROR
debug facilities. # Recursion
ASMBLEIZ 280 Macro assembler £37.50
* Full 2pass Macro Assembler. * iF and ELSE — 255 nesting levels.
* Produces symbol table. * Relative jumps.
UP-GRADE KITS
Trying to add computer with concise step by step
memory is not much fun if you directions and diagrams. And if
dont get everything you need. a personality Jumper is
Receiving unprogrammed required. it’s premade.
jumpers and having to program The TRS-80° memory
them yourself is not much expansion was our first Simple
better. Most important. that’s Up-Grade. Now there are two
the place where the problems more — for owners of Apple
are introduced I"* and Exidy Sorcerer***
So Ithaca Audio’s better idea is computers. Each kit is 100%
the Simple Up-Grade. Each guaranteed — if a part ever
Simple Up-Grade is specially fails. we replace it FREE. Your
designed to make adding Ithaca Audio dealer has them
memory foolproof. We include in stock. only £69. Now you
all the parts you'll need: 8 can afford to add high quality.
prime. tested 16K RAMs. along high density memory to your
system for
remarkably little
— far less than
you would expect
to pay from Radio
Shack. Apple. or
Exidy directly
These Simple
Up-Grades are
Ithaca Audio’s
first step in
adding more
Capability and
reliability to your
computer at
lower cost. Other
Up-Grades are on
the way to your
dealer now.
Now
only
¢69
Ail prices quoted are exclusive of VAT
NEWBEAR COMPUTING STORE —Telephone: Newbury (0635) 30505 Telex: 848507 SIRTON PRODUCTS—Telephone: 01-660 5617
AIRAMCO — Telephone: 0294 57755 Telex: 779808
COMPSHOP LTD — Telephone: 01-441 2922 Telex: 298755
UK & EUROPEAN DEALER ENQUIRIES INVITED — CONTACT
iTHaca [loflerMyysienios
NEW EUROPEAN SUBSIDIARY
58 Crouch Hall Road, London N8 8HG. UK.
Telex: 299568
(formerly ITHACA AUDIO of New York)
Telephone: 01-341 2447
@ Circle No. 189
100 PRACTICAL COMPUTING September 1979
(continued from page 98)
0090-0091
0092-0093
0094-0095
0096
0097
0098
0099-~009A
009B-
009C
009D
009E
OO9F
OOAO
OOAL ~
00A3-00A4
OOAS
00A6
00A7
00A8
OOA9
OOAA
OOAB
OOAC
OOAD
OOAE
OOAF
00OBO
0oBL
00B2
OOB4
OOBS
00B?
0089
OOBA
OOBB
OOBC
OOBD
OOBE
OOBF
0oco
00C1
00Cc2
00C3
00C4L-~00C5
00Ccé6
00C7-00C8
00C9-00CA
O0OCB-00CC
oocD
OOCE
OOCF
00Lo
OoDL
00D2
00D3
OOD4
00D5
00D6-00D7
0oD8
00D9
OODA~OODB
ooDC
OODD
OODE
OODF
00E0-00F8
OOF9
OOFA
OOF B-O00FC
0100-010A
0100-013E
0100-01FF
0200-0250
0251-025A
0258-0264
0265-026E
0 26F-0278
027A-0339
033A-03F9
03PA-03FB
0400-7FFF
144-145
146-147
148-149
150
199-200
201-202
203-204
205
206
207
208
209
210
211
212
213
214-215
216
217
218-219
220
221
222
223
224-248
249
250
251-252
256-266
256-318
256-511
512-592
593-602
603-612
613-622
623-632
634-825
826-1017
1018-1019
1024-32767
8000-8FFF Jerue-16ee?
9000-BFFF 36864-
9151
CO00-EOF8 49152-57592
EOF9-E?7FF 57593-59391
E810-E813 59408-59411
E820-E823 59424-59427
E840-E84F 59456-59471
POOO-FFFF 61
-65535
Hardware interrupt vector
Break interrupt vector
NMI interrupt vector
Status word ST
Which key depressed: 255=no key
Shift key: 1 if depressed
Correction clock
Keyswitch PIA: STOP and RVS flags
Timing constant buffer
Load=0, Verify=1
# characters in keyboard buffer
Sereen reverse flag
IEEE-488 mode
End-of-line-for-input pointer
Cursor log (row, column)
PBD image for tape I/0
Key image
O=flashing cursor, else no cursor
Countdown for cursor timing
Character under cursor
Cursor blink flag
EOT bit received
Input from screen/input from keyboard
X save flag
How many open files
Input device, normally 0
Gutput CMD device, normally 3
Tape character parity
Byte received flag :
Tape buffer character
Pointer in filename transfer
Serial bit count
Cycle counter
Countdown for tape write
Tape buffer#1 count
Tape buffer#2 count
Write. leader count; Read passi/pass2
Write new byte; Read error flag
Write start bit; Read bit seq error
Pass 1 error log pointer
Pass 2 error correction pointer
O=Sean; 1-15=Count; $40=Load; $80=End
Checksum
Pointer to screen line
Position of cursor on above line
Utility pointer: tape buffer, scrolling
Tape end address/end of current program
Tape timing constants
00=direct cursor, else programmed cursor
Timer 1 enabled for tape read; 00=disableda
EOT signal received from tape
Read character error
# characters in file name
Current logical file number
Current secondary addrs, or R/W command
Current device number
Line length (40 or 80) for screen
Start of tape buffer, address
Line where cursor lives
Last key input; buffer checksum; bit buffer
File name pointer
Number of keyboard INSERTs outstanding
Write shift word/Receive input character
#blocks remaining to write/read
Sérial word buffer
Sereen line table: hi order address & line wrap
Cassette#1l status switch
Cassette#2 status switch
Tape start address
Binary to ASCII conversion area
Tape read error log for correction
Processor stack area
Basic input buffer
Logical file number table
Device number table
Secondary addréss, or R/W cmd, table
Keyboard input buffer
Tape#1 buffer
Tape#2 buffer
Vector for diagnestic program
Available RAM including expansion
Video RAM
Available ROM expansion area
Microsoft Basie interpreter
Keyboard, Screen, Interrupt programs
PIA1 - Keyboard 1/0 .
PIA2 - IEEE488 I/0
VIA - I/0 and Timers
Reset, tape, diagnostic monitor
PRACTICAL COMPUTING September 1979
SSS Sa aE 8 Se.
Graphics printer
SIGMA SYSTEMS of Cardiff (telephone
21515) sent a sample of the output from
what it describes as the first available
printer to print Pet graphics. The advan-
tage when reading a program listing is
terrific, of course. Since this is the Axiom
electrostatic printer working at a speed of
120 lines per minute with 40 characters
per line on paper Sin. wide, it is inter-
faced directly to the IEEE bus, so you
need no long subroutines in memory to
run the printer. It costs £499 plus VAT.
| Instant addition
WE HAVE heard of an interesting col-
lection of add-ons from Palo Alto ICs,
810 Garland Drive, Palo Alto, CA
94303.
The Basic Programmer’s Toolkit is a
| collection of firmware aids designed to
enhance the development, debugging and
polishing of programs for the Pet.
The toolkit provides 2KB of additional
machine language tools permanently in
ROM. No tapes need to be loaded, nor
do you lose any RAM. The toolkit adds
these helpful new commands to the Pet:
AUTO enter auto-numbering mode, with the Pet
providing evenly-spaced line number
prompts.
APPEND appends a Basic program from tape to the ||
program in storage, using normal SA¥VEd
tapes
DELETE deletes a range of lines as easily as LIST.
DUMP displays the names and values of variables
in the symbol table during or after running a
program.
HELP used after an error in Basic to display the
erroneous line, with the offending token
highlighted.
RENUMBER _ renumbers a Basic program — and all
references — by specified step-size.
TRACE allows you to see the line numbers of state-
ments as they are executed, in a small scroll
window in the corner of the screen. Also
operates in single STEP mode.
The toolkit will cost $75 for 2001-8,
$50 for 2001-16, 32; that includes
documentation and examples of use.
You will need to order directly from
the States, but the company is interested
in arranging U.K. representation.
Takeover
THE TAKEOVER of Petsoft by Applied
Computer Techniques (ACT) seems to
have had a propitious effect. Twenty-five
new programs are listed in the latest
catalogue, ranging from a £5 program to
teach maths to children of six to 12 years
old, and a tutorial to teach beginners how
to write programs in Basic.
New games include space simulation
for £5, and for £10 there is a steeplechase
game. For £10 you can buy Gypsy
Petulengro, an astrology program which .
might start a new trend on the seaside
piers of Britain.
Copies of the latest free catalogue are
available from Petsoft Division, Applied
Computer Techniques Ltd, 5-6 Vicarage
Road, Edgbaston, Birmingham, B15
3ES. Tel: 021-454 5348.
"TY ANEW
OR A NEW
| TECHNOLOGY
SOFTY is not just another
training aid for the engineer
| 3 wishing to become acquainted
aul 7 hic with microprocessors ~ if 1S a
ff jy Until quite recently all the electronics BENCH-TOOL for the system
f Y/ design engineer really required was a scope
gf anda meter. Now even the smallest of com- designer.
‘ ¥ panies are investing thousands in micro-
processor development laboratories — afraid of
n will probably take place
“A revolutio anoe-of complete
soon, with the appear
being left behind in the technology-race. But 2... nt systems costing less than
) Jf SOFTY is here to help, and a microsystem can be developme:
iY developed without expensive equipment right Gd £1,000...
¥ through the design and prototype stages and even
‘ Fi Address Bus Control Bu:
into production. ; :
WHAT SOFTY WILL DO
@ ITCOPIES MEMORY DEVICES(ROMs &c) presen a the data as an address-mapped
hexadecimal display on the screen of a monitor or TV set.
@ ITOEVELOPS PROGRAMS for virtually any microprocessor with facilities similar to an
ASSEMBLER; you may enter, insert or delete instructions, shift blocks of data, match
specific bytes, calculate displacements to labelled locations — and all with the
overwhelming advantage of being abie to test the program instantly and even developit
one instruction at a time!
@ IT RECORDS PROGRAMS on ordinary cassette tape using an ordinary cassette
recorder at ultra-high-speed — around 2000 baud equivalent!
IT PROGRAMS EPROMS of the 2708 family at a speed which is close to the theoretical
minimum (2 mins per 2708). It may therefore be usedas an'‘instant-copier’ for software
@ ITISAHANOY COMPUTER which may be programmed to do useful jobs in the home or
workshop, and may even be included as the ‘brains’ of larger equipment, performing
sequential or combinatorial control functions. SOFTY has a microcycle length of
exactly one microsecond and there is a programmable timer. The manual lists a simple
interpretive language which anyone may learn to use in ten minutes!
@ (IT IS A FABULOUS LEARNING AID because the trainee can actually see what is
happening — SOFTY is completely transparent! The internal MPU willcease execution
at abreakpoint, which may be substituted for any program step, and display contents of
internal registers.
@ IT FILLS THE GAP BETWEEN THEORY AND PRACTICE for the serious user who
already has a computer and dedicated assembler to develop his software. The
computer makes documentation — not prototypes. SOFTY places the program in
addressing space tobe actioned bythe MPU of his choice inareal system — the proof of
the pudding! Simple debugging and condensing of code may often be handled without
recourse to the assembler
SOFTY can be assembled in a couple of hours. No extras are required except for a
power supply providing +5, +12 & —5 volt rails and +30 volts forthe EPROM programmer,
The kit includes sockets for all the 23 [Cs, UHF modulator for TV use, 4MHZ crystat, DIN
socket and lead for cassette interface, 21 key keyboard, a quality double-sided PCB of
fibreglass with solder mask and component overlay and a comprehensive manual covering
assembly and use.
A DEVELOPMENT KIT is also available which includes all of the above and a lever-
operated ZERO INSERTION FORCE SOCKET for the EPROM programmer, 43 way card
edge connector, ribbon cable and 24 pin header (for connection to the system under
development as firmware) and a spare 2708 EPROM lo Cassette
itis not possible to present a full technical specification in the space avallable here. We
will therefore send you a SOFTY on the yadarsigeding that you may examine it andread the Recorder
literature and, if you wish to do so, return the goods for a complete refund within 14 days
CONTROL LOGIC
Av 1dSi0 TWNSIA
lo TV
VIDEOTIME PRODUCTS, 56, Queen Road, BASINGSTOKE, Hants, RG21 1RE uy
TEL: (0256) 56417 TELEX: 858747. Y : r
We welcome Barclay & Access orders by telephone. ms ; se = BS . : Bq
: uy {im Sit) XD
I Please send me: (| enclose Cheque/Company Order) = ES ESSE SS
bi SOFTY Kits @£92.00(Incl. VAT & 50p p & p) ~ 1 =
ay cee DEVELOPMENT Kits @£113.85(Incl. VAT & 50p p & p) BS RS
...... BUILT DEVELOPMENT Kits @£136.85(incl. VAT & 50p p & p) ca ies
OA POWER SUPPLY Kits @£17.25(incil. VAT & £1 p & p)
PORTA PORT B
aS pea See ee
: >
E Q
Qa
a
to)
n
n
OPTY
®@ Circle No. 190
102 PRACTICAL COMPUTING September 1979
EE ee eee
Pascal
ANNOUNCED at the NCC trade fair in New
York was a language card designed to run
Pascal. It is in the form of a 16K RAM
card, bringing the total capacity of Apple
II to 64K.
The card supports the full USCD
Pascal and the high-resolution colour
graphics extension designed by Apple;
Pascal is compiled, making program run-
ning shorter. Features of the package
include:
@A fast, screen-orientated editor for
program development and word pro-
cessing.
@ 80-character lines in the standard
Apple with horizontal scrolling.
@ 80-character lines upper- and
lower-case characters — with external
CRT terminal.
@ Standard Pascal plus extensions for
Strings, disc files, graphics and system
programming.
@ Text procedures for cursor addressing,
split screen, horizontal scrolling.
@ FUNCTION Keypress tells whether a
character is available.
@ Library routines include randomising,
support for a game paddle, and several
others.
@ Re-locatable assembly language
routines can be generated and linked
to Pascal programs.
Apparently Pascal operates only on a
48K Apple from disc with the language
card installed. Because of the way the
memory is mapped it may not be possible
to use it with smaller machines.
Required reading
WE’VE MENTIONED The Rainbow pre-
viously in this page; it’s the only inde-
pendent newsletter of which we know for
Apple IT users, and is from Aresco, which
also does newsletters for Pet and the
RCA Cosmac VIP.
Rainbow carries news, reviews, tips,
programs and explanations; and the
potential of the newsletter to react to
readers’ input can justify a subscription.
Rainbow has some 24 pages and is
monthly, Assembled and written largely
by Rick Simpson, it uses two contributing
editors and a number of readers’ articles.
In issue 1, the major piece is the
code and description for a data man-
agement system using Applesoft, 32K
RAM and a disc. It’s not exactly a full-
scale DBMS but it provides a common
format for storing files of numeric data
which can be analysed subsequently by
various applications; it can be used with-
out any great understanding of prog-
ramming techniques, and it looks well-
suited to the production of business and
technical charts and graphs. It has two
bugs, corrected in later issues.
There is also an excellent piece on how
to use the Apple I/O connectors. How
many other computers have built-in
interfaces for paddles and pushbuttons?
Issue 2 contains another good intro-
PRACTICAL COMPUTING September 1979
duction, this time to high-resolution
graphics and shape tables. There are four
software reviews, including plaudits for
Muse’s great Escape game and the Qual-
ity Software Fastgammon.
In issue 3 there is a handy DOS
memory map, a look at the good points of
integer Basic, a tip from Steve Wozniak,
a good review of low-resolution graphics,
and a fine high-resolution plotting prog-
ram for polynomials. There are also the
plans for an add-it-yourself colour killer
to improve text display by showing |
monochome alphanumerics; some pro-
duction Apple IIs are now incorporating
this modification but yours may not have
It.
There is an introduction to assembly
language programming in issue 4,
designed deliberately to fill the gaps in
published books on 6502 machine lan-
guage coding. More articles will follow in | ‘Etch-a-Sketch’ fashion. Hitting the
the series. There are also several reviews,
including the Programmer's Aid ROM
and the Mountain Hardware clock board
[a
For COLOUR Fone’. REPRR TO
1 REM
ar SZ
60 FRINT
ene
SO FRINT “HIT
! IWGIG3.9
100 X - POL (0) 2 ¥
as nf
eer ra FAROE.
gen a
) REM
FEM
REI
ws FRANT
> INPUT
Tr eae
CHV SI IE
Ca a
“COLOUR ETCH -f4
MAUL £.
SPACE RAF
= KETCH"
PANULE
PRE v1)
Bese Ti PeLuUR. =."
THEN
(300+)
HOT B16
&
IS) FMKE ~1é3468)0
el
RETURN
PRINT
PRINT "MAGENTA"
"BLACK" = RETURN
> RETURN
"TARR BLES os RETURN
"PURPLE" = RETURN
“TAR GREEN" > RETURN
“GREY” = RETURN
"MEDIUM BLUE" : RETURN
“LIGHT BLUE" : RETURN
"BROWN" = RETURN
"ORANGE" = RETURN
"GREY" ° RETLIRN
“PIMNE" 2: RETURN
“GREEN = RETURN
"YELLOW" = RETURN
"ADUA" = RETURN
"WHITE" = RETURN
R05 PRINT
OO PRINT
FRING
a3 PRINT
vs PRINT
PRINT
Of FIINT
30 PRINT
210 FRINT
FRINT
2 FRRINY
3 FRINT
FRINT
27 PRINT
', FRINT
|
}
}
PPM Fr
Al
TOU START /CHANGE UC GLAUR"
"1G384) 127 THEN GOSUR 200
HERCUITINE PLOTS REMITRED OOur.
“OUT GF RANGE, TRY AGAIN’ =
PE
— “well-designed, well-constructed and
well-documented. If you have an appli-
cation which requires precise time-of-day
information or precisely-timed inter-
rupts, this unit will do the job’— and do it
well’,
Issue 5 looks in more detail at the
Programmer's Aid and recommends its
extra high-resolution facilities. Also a
fairly unfruitful interview with Apple’s
marketing manager, letters and reviews
— including a look at the Eclectic Corp
Superchip we noted two issues ago.
The superchip is a ROM package for
special graphics, including lower-case let-
ters and plenty of text display variants.
The reviewer found several small limi-
tations with it, especially when running
programs not designed for use with the
Superchip, and concluded that “‘it does
everything they say it will — and very
well — but it also does some things you
wish it wouldn’t’.
Our verdict is unqualified approval.
There is no U.K. outlet so far as we
know, though Aresco is interested in talk-
ing to dealers and shops here. Meanwhile,
individuals can subscribe for $25; Aresco
accepts Mastercharge and Visa. The
address is The Rainbow, P O Box 1142,
Columbia, MD 21044.
Number painting
S W HILTON of Lambeth sent a program
which allows the more artistically-
inclined user to paint by numbers, in
space bar, or the next required colour
code, allows the ‘‘electroartist’’ to change
colour as desired. Well, at least it’s not so
messy as the real thing:
RR et]
GUTa Zag
103
COMPUTER SERVICES |
North-East England Dealers for a range of Microcomputers and Printers
HARDWARE:
APPLE II AIM 65
ZENTEC ZMS-70 ACORN
PRINTERS
ANADEX
DIABLO DAISYWHEEL
SOFTWARE:
INVOICING PACKAGE, CASHFLOW PACKAGE, DENTIST PACKAGE
Selection of Software from Keen Computers Ltd
Tel: John Page on (0632) 482359 482984 to discuss your requirements.
NEWCASTLE-UPON-TYNE
By Gentlemen, the Petdisk
@ Circle No. 191
a =ah fas landed... £499
The U.K.-designed and manufactured Novapac disk system
for Commodore's PET*, first seen at Compec ‘78, is (after
extensive industrial evaluation), now available to the domestic
user. Its unique saddle configuration continues the integrated
design concept of your PET, with no trailing wires or bulky
desk-top modules.
* Novapac may be used with any available RAM plane.
%* May be used with latest versions of 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 } Mbyte on-line storage (4 drives).
* Dual head and 2D versions provide 2 Mbytes on-line.
* Industry Standard IBM 3740 recording format for industry-
wide media compatibility offered 6niy by NOVAPAC.
* Dedicated Intel 8048 microprocessor and 1771 FDC minim-
ise PET software overhead.
%* Local hardware and software support available, including
applications packages for smail business use.
analog electronics
(single disk)
The sophisticated Disk Operating System is disk-
resident, which allows for future DOS-enhancements
Without hardware alterations. PDOS supports multiple
file handling, allocating disk space dynamically to
each as and when necessary. Any file may occupy
from 1 to 600 sectors as required, at up to 16 non-
contiguous locations on the disk, PDOS may be used
alone, or within a BASIC program and offers user-
specified password security for any file. Multiple
access-modes simplify BASIC program construction,
and the user may generate tailored DOS modules.
Novapac dual-disk system complete with PDOS and
BASIC demonstration programs on disc £899 + VAT.
Available from the manufacturer or selected dealers.
Terms: 50% with order, balance on delivery.
Full cash with order is subject to 5% discount.
VAT-FREE Export arranged (Must be shipped by us).
47 Ridgeway Ave,
Coventry
Tel: (0203) 417761
@ Circle No. 192
PRACTICAL COMPUTING September 1979
ULEUSTRATINCHBASIC:
( QARSIMPLEBPROr AMAIA BEARCORCED)
WE CONTINUE our
series of articles on how
to program in Basic,
probably the most widely
used programming
language for small
computers.
For the series, we
have obtained the
serialisation rights for
one of the best books on
the subject, ///ustrating
Basic by Donald Alcock.
*
Each month, we are
publishing a part of the
book, so by the end of
the series you will have
the complete book.
It is written with a
distinct informality and
has a rather unusual
presentation; but it is
this style, we believe,
which makes it one of
the most easy to read
tutorials.
*
Alcock //lustrating Basic
c Cambridge
University Press.
Reprinted by permission.
*
CORTEATS
[prerace
1 (omponents OF THE LANGUAGE
2. [xpur & OUTPUT » EXPRESSIONS AND FUNCTIONS
p3) e Sonrror
4. ENrrays
3. MM arrices
Go (@omecere EXAMPLE PROGRAMS
a), (OMMANDS AND SIGNING ON
8 Q Pues OF DATA
FILES OF DATA = THE COMPUTER®S LONG-TERM MEMORY
KINDS OF FILE < A ROUGH ANALYSIS
§) 9 Syntax
Ghevex
39
i)
TS:
10]
111
ng
120
124
127
132.
PRACTICAL COMPUTING September 1979
105
901
6461 4aquiandes ONILNdWOD WDILDWud
FILES OF DATA
Mspcam !
fea THE KEYBOARD IS NOT THE ONLY MEANS OF INPUT <—@ i
NOR !S THE TERMINAL THE ONLY DESTINATION FOR OUTPUT o
St FAR WE HAVE SEEN THIS2
10 INPUT A(t, A(tst), AGS2) oe I 2) aeons
PR)
[70 [5]
Oe
20 PRINT A(1,1)3A(1,2)
LO ©
"Sea SPERMINE
(Sur yOU MAY ALSO SEND DATA TO AND FROM A F/LE IN THE
F/LES AREA WHICH IS USUALLY ON MAGNETIC DISKs$
COMPUTER
anne ©
COMPUTER
[Pites ARE NEEDED MAINLY FOR? :
LP COMMUNICATION 2 RESULTS OF ONE PROGRAM MAY
BE STORED IN A FILE FOR SUBSEQUENT USE AS
INPUT DATA FOR OTHER PROGRAMS oa
xp BACKING STORAGE A PROGRAM MAY GENERATE
MORE INTERMEDIATE INFORMATION THAN BAS/C
CAN HOLD IN THE FORM OF ARRAYS (EVERY SYSTEM
HAS iTS OWN LIMIT ON SIZE OF ARRAY Deo i
pb TRANSFER DATA BETWEEN ARRAYS IN A PROGRAM AND FILES IN
THE FILES AREA USES joie q PAGE 18 ) Ld
MAT INPUT (PAGE 96 yp :
PRINT (PAGE 28 p '
PRINT USING @ PAGE 34 )
MAT PRINT (PAGE 98 yp =
EXCEPT THAT YOU INSERT A CWANNEL NUMBER @ FOLLOWED BY A
COLON }) AFTER THE WORD “INPUT” OR “PRINT”
ILLUSTRATING BASIc PAGE 120
G vigitee 3
PJERE 1s A SUBROUTINE TO TRANSFER ROWS { TO “N” OF ARRAY A(,)
TO A FILE ON CHANNEL 7:
REM SUBROUTINE TO TRANSFER N ROWS 1) 2) 3)
REM OF A(,) TO FILE ON CHANNEL 7: Ad,
FOR L=1 TON A(2,
PRINT 7: A(1,1),A(Z,2),A(L,3) A(3,
NEXT 1
RETURN
IF YOU “CALLED” THIS SUBROUTINE A SECOND TIME TRE NEW CALL WOULD
CAUSE MORE ROWS OF NUMBERS TO BE APPENDED TO THE FILE
FOLLOWING THOSE TRANSFERRED IN THE PREVIOUS CALL. THUS YOU CAN
STORE AN “ARRAY” IN A FILE MANY TIMES LONGER THAN ALLOWED
FOR BY THE “DIM™ STATEMENT FOR THAT ARRAY o
[HERE 1s A SUBROUTINE TO INPUT JUST “RECORD R”
FROM A FILE ON CHANNEL G: o WE ASSUME THIS FILE HAS THE
SAME STRUCTURE AS THE FILE ON CHANNEL 7: ILLUSTRATED ABOVE o
A FILE {S SIMPLY A STREAM OF SINGLE ITEMS $ YoU HAVE TO
ORGANISE ITS STRUCTURE @ SUCH AS ROWS OF THREE AS “RECORDS”
AS IN THIS EXAMPLE Do /
REM SUBROUTINE TO INPUT SINGLE RECORD
2010 REM "R“ INTO BC) FROM CHANNEL 6:
2020 REM FIRST RESET FILE TO RECORD 1
2030 RESET 6
2040 REM WIND THROUGH (R-1) RECORDS
2050 FOR L={1 TO R-1! crm
2060 INPUT 6: A,B,C i R-1
2070 NEXT L RECORDS BU) B(2) BG)
2080 REM NOW INPUT RECORD R TO BC)
2090 INPUT 6: B(1),8(2), B(3)
RETURN
TRIS EXAMPLE ILLUSTRATES THE INSTRUCTION “RESET” WHICH IS COMMON
TO MANY BAS/€5 ALTHOUGH AT LEAST ONE VERSION USES THE WORD
“RESTORE? INSTEAD « YOU ARE USUALLY PERMITTED TO RESET
SEVERALS CHANNELS BY A SINGLE INSTRUCTION 3
(00 RESET 1,3, 6
APHIS INSTRUCTION MOVES A CONCEPTUAL “POINTER” TO THE BEGINNING
OF THE FILE ON THE SELECTED. CHANNEL SO THAT THE NEXT “INPUT”
INSTRUCTION TO BE OBEYED PICKS UP THE FIRST ITEM IN THE FILE o
DO NOT USE “RESET” WHILST PR/W7ING A FILE o
ILLUSTRATING, BASIC PAGE (2!
6461 Jequiaidas ONILNdWOD TWOILDVud
401
CHAPTER &
FALESAAMES STCHAWMELS |
\AAHEN THERE ARE FILES IN A BAS/C PROGRAM YOU HAVE TO ASSOCIATE
NAMES OF FILES AS THEY APPEAR IN YOUR “CATALOG”? WITH THE
CHANNEL NUMBERS USED IN “INPUT” AND “PRINT” INSTRUCTIONS «
Q* CATALOG’ 15 EXPLAINED ON PAGE 1152) THERE ARE ALMOST AS
MANY WAYS OF DOING THIS AS THERE ARE VERSIONS OF BASIC «
ASSUMING YOU WANT TO INPUT FROM A FILE CALLED “MYDATA” ON
CHANNEL 6: AND PRINT A FILE CALLED “RESULT” ON CHANNEL 7:
HERE ARE JUST A FEW DIFFERENT WAYS DIFFERENT BAS/CS REQUIRE
YOU TO DBO IT, @ NAMES YOU INVENT ARE USUALLY LIMITED TO ABOUT
6 LETTERS AND DIGITS OF WHICH THE FIRST MUST ALWAYS BE A
LETTER o)
10 FILE 46: “MYDATA"
20 FILE #7: “RESULT”
10 FILES #6 = "MYDATA” , #7= “RESULT“
SIZE IN BLOCKS
= wyyOF 024 CHARS.
1,2,3,4,5, "MYDATA‘/10, "RESULT "/10
10 FILES CHANNELS
NUMBERE D
By Pos/TIon
IN LIST
$0 FILES A;B3C;D;E;MYDATA; RESULT
a
INPUT FILES
DISTINGUISHED
FROM OUTPUT
FILES
OPEN 6= “MYDATA", INPUT
OPEN 7= "RESULT" , OUTPUT
A
—
OPEN "MYDATA" FOR INPUT AS FILE 6
OPEN "RESULT" FOR OUTPUT AS FILE 7
OPEN "MYDATA" TO :6, INPUT
OPEN "RESULT" TO :7, PRINT
A FURTHER COMPLICATION JS THAT SEVERAL SAS/CS DEMAND YOU
FIRST USE THE “JOB CONTROL LANGUAGE ” (@72.e. THE CODE
UNDERSTOOD BY THE COMPUTER®S OPERATING SYSTEM } TO
DECLARE AND GIVE DETAILS ABOUT ALi THE FILES YOUR BAS/C
PROGRAM REFERS TO 8 IN SHORT TO GIVE DETAILS TWICE 2
ILLUSTRATING BASIC Page {22
PILES ( cots)
Jou cAN FILE TEXTS AS WELL AS NUMBERS $
100 REM FILE NAMES AND DATA
110 PRINT 7: “CUSTOMER'S NAME "3 N$;5¢
120 MAT PRINT 7: A
ae
BUT SOME BAS/CS RESTRICT SUCH MIXTURES OF TEXTS AND NUMBERS
TO FILES CODED IN CHARACTER FORM AS DEFINED OVERLEAF»
[Prom THE PRECEDING EXAMPLES YOU WILL APPRECIATE HOW EASY IT
WOULD BE TO PRINT A FILE AND GET !T OUT OF PHASE DURING
RE-INPUT 3 REMEMBER YOU CAN®°T SEE THE CONTENTS OF A FILE >
HERE 'S A ROUTINE TO INPUT ON CHANNEL Gt THE FILE PRINTED BY
INSTRUCTIONS 100 TO {20 ABOVE ON CHANNEL 7: o
a,
200 REM RE-INPUT CUSTOMER'S NAME & DATA_
210 INPUT 6% Me, Q$
220 MAT INPUT 6: A
BUT THERE IS A HORRIBLE BUG eo THE TEXT “CUSTOMER'S NAME " WAS
PUT ON THE FILE IN FRONT OF THE CUSTOMER®S TWO NAMES STORED
IN N$ AND S$ 8 LINE 210 FAILS TO PICK THIS UP , THUS MAKING
S$ INTO THE FIRST {TEM OF MATRIX INPUT WHICH [S RIDICULOUS .
When DEVELOPING PROGRAMS THAT USE FILES IT HELPS TO SEND,
SAY, THE FIRST OR LAST ITEM IN EACH TRANSFER TO THE
TERMINAL AS A RUNNING CHECK. THE (@ CORRECTED 2 DEVELOP-
MENT VERSION OF THE ROUTINE ABOVE BECOMES $
REM RE-INPUT CUSTOMER'S NAME & DATA
P 6: T$,M
INPUT $, M$, Q$ mm hy
PRINT 2103 Qs —— & 22) JUST FOR
MAT INPUT 6: A DEVELOPMENT
PRINT 220; A(1,1)
Lo
ILLUSTRATING BASIC PAGE 123
80
6261 sequaadas ONUNdNOD TIWOLLDVud
- CHAPTER Sie
RANDS IO) BFALE:
VW Puere ARE ESSENTIALLY FOUR KINDS OF FILE2 SOME BAS/CS
‘OFFER ONLY ONE. KIND, OTHERS MORE, HERE IS A’ ROUGH
ANALYSIS $
eo
°o
0
°
°
2 q OFTEN CALLED
o
<i a RANDOM :ACCESS ))
o
°
0
aN THE DOMAIN OF FILES THERE IS A “VERTICAL” DIVISION
SEPARATING SEQUENTIAL FILES FROM D/RECT ACCESS FILES «
SEQUENTIAL FILES EACH FILE HAS A CONCEPTUAL “POINTER” WHICH
‘STARTS AT THE BEGINNING OF THE FILE AND
Pn: MAY BE SET -BACK TO THE. BEGINNING AT AMY
TIME BY THE INSTRUCTION “RESET” o
WHEN YOU SEND INFORMATION TO -THE FILE an mower — -
BY THE “PRINT” INSTRUCTION THE NEW
INFORMATION, GOES ON ‘THE END OF THE FILE
AND THE: POINTER MOVES ON JUST PAST THE
NEW. END THUS CREATED.
WHEN YOU INPUT INFORMATION FROM A FILE
YOU GET THE INFORMATION POINTED TO
4 THE POINTER -THEN MOVES ALONG TO THE
NEXT SET OF INFORMATION READY FOR
THE ‘NEXT “{NPUT®? INSTRUCTION o
OBVIOUSLY, THEN, YOU CAN°T “INPUT”'FROM A FILE BEING “PRINTED”
UNTIL YOU HAVE FINISHED WITH PRINTING AND “RESET” THE
CONCEPTUAL POINTER IN SOME. BAS/CS THIS MEANS.CLOSING AN
OUTPUT FILE -AND OPENING IT AGAIN AS’ AN INPUT FILE @ ON
THE SAME OR ANOTHER CHANNEL, EXAMPLES ON PREVIOUS
PAGES ./LLUSTRATE THE USE OF SEQUENTIAL FILES o
DIRECT ACCESS. FILES (THESE ARE OFTEN CALLED RANDOM ACCESS FILES?
A -MISNOMER BECAUSE NOBODY WANTS RANDOMLY CHOSEN RECORDS «2 WITH
DIRECT ACCESS FILES YOU MAY CONTROL THE POSITION OF THE POINTER»
WHEN THE POINTER IS IN POSITION YOU MAY TREAT THE FILE AS
THOUGH IT WERE A SEQUENTIAL FILE] SO BAS/CS THAT PROVIDE
DIRECT ACCESS FILES MUST ALSO PROVIDE SPECIAL INSTRUCTIONS FOR
MOVING POINTERS TO “RECORD N” AND FUNCTIONS FOR DISCOVERING
WHERE THE POINTER HAS GOT TO. DIRECT ACCESS FILES ARE LESS
COMMON IN B8AS/C THAN SEQUENTIAL -AND ARE NOT FURTHER COVERED HERE,
ILLUSTRATING BASIC PAGE 124.
CHAPTER ©}
SPHERE. IS ALSO A “HORIZONTAL” DIVISION OF THE DOMAIN OF FILES
SEPARATING CODED FILES -FROM B/NARY FILES o
CODED S CODED
SEQUEN 3 DIRECT
ACCESS
NNN
BINARY
SEQUEN
-TIAL
CODED FILES you CAN PRINT THESE AT .A TERMINAL OR ON A
LINE PRINTER <— EVERY LETTER, DIGIT AND SYMBOL IN THE FILE
IS UNIQUELY -STORED$ USUALLY IN A:S-C.1.f CODE. A PROBLEM
WITH CODED FILES !S THAT COMPUTERS USING BINARY ARITHMETIC
HAVE TO CONVERT NUMBERS FROM CODED DECIMALS TO BINARY
DURING INPUT <* AND FROM: BINARY TO CODED DECIMALS DURING
OUTPUT 2 THIS IS WASTED WORK IF YOU DON°T NEED TO PRINT
THE FILE AND READ !TS THERE CAN ALSO BE .SQME LOSS OF
ACCURACY DURING BOTH CONVERSIONS .
BINARY FILES THESE STORE DATA -MORE COMPACTLY THAN !S
POSSIBLE WITH .CODED FILES AND REQUIRE NO CONVERSION DURING
INPUT AND OUTPUT. ON THE OTHER ‘HAND THEY WOULD PRODUCE
GIBBERISH iF YOU WERE ABLE TO PRINT THEM AT JHE TERMINAL,
BINARY FILES ARE STRICTLY -FOR STORING INTERMEDIATE ‘RESULTS
‘OF: A CALCULATION «% -AND READING THEM BACK INTO THE. COMPUTER
FOR FURTHER COMPUTATION. SEVERAL BAS/CS OFFERING BINARY
FILES IN ADDITION TO CODED FILES HAVE DISTINCT INSTRUCTIONS
FOR BINARY INPUT AND OUTPUT 3 TYPICALLY $
THE WORD “GET” IN PLACE OF “INPUT ”
THE WORD “PUT” IN PLACE OF “ PRINT”
AND SOME USE ‘THE WORDS “READ” AND “WRITE”. RESPECTIVELY.
SOME BAS/CS ALLOW BINARY FILES CONSISTING OF TEXTS. A FEW
BAS/CS ALLOW BINARY FILES COMPOSED OF A MIXTDRE OF NUMBERS
AND TEXTS»
‘ere IS NO HOPE OF WRITING COMPLETELY PORTABLE BAS/C PROGRAMS
WHICH USE FILES «% BUT IF YOU STICK TO USING CODED SEQUENTIAL
F/LES YOUR PROGRAM SHOULD NOT NEED MUCH ALTERATION TO
MAKE IT RUN ON SOME OTHER INSTALLATION o
ILLUSTRATING BASIC PAGE 12.5
XITAN SYSTEMS
THE SOUTH’S PREMIER MICROCOMPUTER SUPPLIER.
WE SUPPLY SYSTEMS — LOOK AT THESE TYPICAL CONFIGURATIONS!
System A 32K Commodore PET + Commodore model 2040
Dual floppy drives and cable. £1,610
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double-density drives, 2 serial, 1 parallel port,
DOS and BASIC, high-quality brand name 24 x
80 char VDU £2,505
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dual minifloppies, 21 connectors, 1 serial, 1
parallel printer port, CDOS 1.07 and Extended
Disk BASIC High-quality brand name VDU
etc £3,020
System D CROMEMCO 2-2, 4MHz, 1 megabyte floppy disk
storage, 64K RAM, 3 serial ports, 2 parallel ports,
CDOS 1.07 and BASIC, High-quality 24 x 80 char
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System E CROMEMCO System 3 (the ‘Rolls Royce’’) 64K
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We supply Centronics, Teletype 43 and Diablo Printers, plus the normal range of
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23 Cumberland Place, Southampton SO1 2BB.
Tel. (0703) 38740 Tues-Sat
@ Circle No. 193
PRACTICAL COMPUTING September 1979 109
Your Own Complete :
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ito PRACTICAL COMPUTING September 1979
Fourier transforms on
WE PRESENT an entirely practical, non-
mathematical and basic — and Basic —
description of how to take a single cycle
of any waveform and reduce it to its com-
ponent parts, revealing in some detail the
‘nuts and bolts’ which go to make up all
kinds of sounds and vibrations. This
should prove of considerable interest to
Pet owners who also happen to be musi-
cians, engineers, mechanics, teachers and
students in various branches and stages of
physics and elementary mathematics.
It is possible, and sometimes useful, to
describe any periodic waveform in terms
of a number of pure sinewaves. Fourier
analysis is a technique which can be used
to extract each of the possibly numerous
harmonics that constitute a complex
waveform. Harmonic content dis-
tinguishes the tone of ore musical
instrument from another, even though
they are playing the same note.
Spoken vowel sounds are ditterent
because the throat, nose and mouth form
filters with different resonant frequencies
which emphasise certain of the harmonics
by Nick Hampshire
inherent in the sound produced by the
vocal cords. As we speak, the shape of
the mouth changes continually, altering
the patterns of the harmonics produced in
the sound, so allowing the varied range of
sounds we use for communication.
The number of times a waveform —
which could be sound or vibration in any
material or structure, or a mathematical
function — repeats in a given period — or
axis space — is called the fundamental
frequency. Harmonics are tones which
are integer multiples of the fundamental.
Thus, if a waveform has a fundamental
frequency of 100 cycles per second
(Hertz), then the second harmonic is
twice that frequency — 200Hz, the third
300Hz, the 10th 1000Hz, and so on.
A complex waveform, such as the tone
produced by an oboe or the human voice,
can be regarded as containing a certain
amount of a pure sinewave at the fun-
damental frequency, a certain amount of
sinewave at the second harmonic, some at
the third and so on. Most complex
waveforms will have harmonics stretching
to a theoretical infinity — i.e., an infinite
number of harmonics must be added to
the fundamental to build up the exact
waveforms.
In practice, the higher fundamentals
tend to add only a very small proportion
of energy to the total and may be ignored
at some arbitrary level. An audio
amplifier being fed with a squarewave,
which is rich in harmonics, of 1 KHz will
pass only the first 20 harmonics or so
PRACTICAL COMPUTING September 1979
the Pet
because it has an upper frequency limit of
20KHz. That will lead inevitably to a dis-
torted squarewave being fed into the
loudspeakers, since the theoretical har-
monic series of a squarewave continues to
infinity in the sound spectrum.
Figure 2 shows the relative content of
the first 15 harmonics, showing that the
higher harmonics are less and less sig-
nificant and contribute less to the final
sound. Such distortion may not be par-
ticularly important, as the human ear
cannot hear these higher harmonics. This
transcription error, however, would be
detected by audio test equipment.
It may not be immediately obvious that
Figure I.
GRAFH OF SINE WAVEFORM
LOWER BOUNT
UFFER LIMIT
-99. 8026728
99. 8026728
wou
THERE ARE SO FOINTS
ii it di dk kh iw OH
CS cc eC Th
* %
*
iP Waa if OP a
*
a periodic waveform need consist of only
its fundamental — the period with which
it repeats — and harmonics of that fun-
damental. Note, however, that fun-
damental frequency means just that. If
the waveform contains any component
waveform not an integer multiple of the
fundamental, the fundamental was cho-
sen incorrectly.
Harmonic analysis of the tides might
show that the fundamental frequency of
oscillation was the lunar month. After all,
it is the attraction of the moon which
causes the tides. Should the sun have any
effect on the tides, the periodic fun-
damental would have to be the lowest
common denominator between the effect
of the moon and the sun.
A practical tide predictor, which is one
application for such analysis, may, for the
(continued on next page)
Uf
Computabits =
(continued from previous page)
sake of simplicity, ignore the minor effect
of the sun if the prediction is accurate
enough.
Figures 2 and 4 show the harmonic
content of a square wave and a triangle
wave. Figure 2 shows that the square
wave contains a greater proportion of
harmonics than the triangle. Both contain
only odd harmonics — fundamental,
third, fifth, seventh and so on — yet in
| one case they add up to a square wave
and in the other a triangle. This is due to
phase differences between the harmonics.
If one considers two sine waves of the
same frequency (as figure 1) and
superimposes them, when the peaks
occur in the same place both the peaks
and the troughs are magnified. The new
waveform is the sum of the two.
If the second waveform is shifted along
half of the total wavelength (180 degrees)
the peak of the first would be summed
with the trough of the second, similarly
with the trough of the first and the peak
of the second.
The nett result would be of the two
waveforms cancelling-out to leave
nothing at all. When two stones are
Figure 2.
HARMONIC CONTENT OF SQUARE WAVEFORM
HARMONIC VALUE
dropped in a pond and the ripples meet,
the wavelets are amplified in some places,
reduced to still water in others.
Three peaks
The third harmonic has three peaks in
the same length, space or time as the one
of the fundamental. When the third har-
monic is added to the fundamental in
such a way that the peak and trough of
the fundamental are accentuated, then a
triangle wave is produced. When the
third harmonic reduces the peak and
trough of the fundamental, a squarewave
is formed. .
All the examples were generated. by
the program given at the end. Fourier
analysis is set firmly in the realms of
applied mathematics, although we settle
for a descriptive, and, where possible, a
pictorial approach. No attempt will be
made to prove, or even show, that the
technique or theory is soundly based.
The program is in several logical sub-
sections. First, the user has the option to
generate a waveform within the code by
calling one of a number of subroutines, or
to input a sequence of numbers rep-
resenting a digitised waveform. In the
second section the user may print-out a
1 AO IOI IO IOI IOIOIOIIOIIOOIOIOIOIOIGIOIOIOIOIOIOIOIOIOIOIOI ICICI IOI CIO IK
+
3
a
+
+
3 III IOI IK
+
+
4 $x
+
+
POO OK
+
Ls]
ba
+
6 +*
3
q
7. FIO K
+
e
8 +k
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+
9 PORK
+
a
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+
11 ek KKK
112
ar
graph of the waveform so produced,
either on the Pet screen, or to an external
printer through an IEEE bus-to-RS232
converter.
The third stage is to analyse the
waveform once for each harmonic, print-
ing the amplitude of that harmonic and its
phase angle. They are the two items of
information required to say how much of
each harmonic must be added to the fun-
damental, and in what phase relationship.
In the last section the user may print-
out a pictorial representation of the har-
monic content, either on the screen or the
external printer. As a further option the
bar chart of the harmonics may be dis-
played as a logarithmic value; this has the
effect of compressing widely-diverging
values, so making the display more
usable.
When the program is started it asks the
user for the number of sample points the
waveform is to contain (120). Ten or
fewer are too few for a meaningful analy-
sis, more than 255 would not fit in a Pet
Basic array (130-150).
Next, the user must select one of six
options to set up the waveform in the
array WV (160-250). If a zero is entered
the program executes subroutine 1000
(260-280). This subroutine then asks the
user to input NO — the number of sam-
ple points — digitised waveform points.
If the user typed “1” when selecting
the waveform option, WV is set equal to
a sine wave (1100-1150). The inherent
SIN() function is called. It takes a value
in radians — there are X 2*PI radians ina
full circle, equivalent to 360 degrees; this
accounts for the 6.283... constant in the
calculation (1130).
Normalising
SIN() returns a value in the range —1
to +1; this is multiplied by 100 to nor-
malise it partially with the other
waveforms and also to provide reason-
ably large numerical values from the cal-
culations.
By selecting option ‘*2’’ a square wave
is placed in WV (1200-1290). The first
half of the array is set to —100, the sec-
ond half to +100. A triangle wave,
option “3” (1300-1375), is constructed
by starting a counter at zero (TM, state-
ment 1310) adding +10 for the first quar-
ter of the cycle (1315-1330), then sub-
tracting 10 for the next half of the cycle
(1335-1350).
The last quarter of the cycle is con-
structed by adding +10 to the counter
until it reaches zero again (1355-1375).
A sawtooth waveform, option ‘4’
(1400-1470), is produced by starting TM
(1420) at a negative value chosen to give
a ramp equally above and below the zero
line. The last option “5” (1500-1520)
shows a ‘clipped’ sine-wave, as might be
produced by an overloaded audio
amplifier. Here the sample point is
limited to 85 percent, both positive and
PRACTICAL COMPUTING September 1979
a (| || aa
negative, of its full value. In each case the
string variable HD$ is loaded with the
name of the waveform which will be used
later as a header for graphs.
Having placed one cycle of a periodic
waveform in WV it might be useful to
print it out, either on the Pet screen or to
an external printer. A “YES’/*NO”
reply is expected to two questions —
“DO YOU WANT A PET GRAPH”
(320-340), in which case subroutine 3000
is called; and “DO YOU WANT A
PRINTER GRAPH" (350-370), in
which case subroutine 4000 is called.
Printing a graph like this is a useful
general subroutine. It is unfortunate that
two separate subroutines are required,
one for the screen and one for the printer,
but in Pet Basic it appears to be imposs-
ible to use one type of write statement to
write both.
Values
The algorithm, however, is the same
and remarks about one generally will
apply to both. A line-printer graph is
most conveniently produced by drawing
the Y-axis first as a line across the page or
screen. Then, for each point, printing a
single character for the X-axis line, a
number of spaces, followed by a°‘*” or
some other character to represent the
point value. It is also important to ‘nor-
malise’ the upper and lower limits of the
graph to the smallest and largest value in
the array of points to be displayed.
Subroutine 4500 places the smallest
and largest values to be found in WV into
MN and MX. Again the algorithm is a
simple and effective one. MN and MX
are loaded with the first value in WV —
WV(1) (4510-4520). Then the remaining
values are checked; if any value is greater
than MX it is placed in MX (4540) and if
any value is smaller than MN, it is placed
in MN (4550).
Both the graph plotting routines first
print-out a header consisting of the name
of the waveform — from HD§$, the upper
and lower graph plot limits and the
number of points which make up the plot
(3030-3050 or 4030-4120). Next a line
of ‘hash’ characters is printed to form the
Y-axis line (3060-3090 or 4130-4160).
The line length is fixed at 39 for the Pet
as its screen ts 40 columns wide, but it will
be varied for the printer according to the
paper width in use. The column width is
stored in the variable PW, which is set
initially to 70 in statement 54. One line of
output is generated for each waveform
point.
TW contains the total width of the plot
(3120 or 4190) and each point will be
some proportion of this (3130 or 4200).
0.5 is added to the value generated
before the function INT() is applied,
which has the effect of rounding the value
in SP to the nearest integer. This is a use-
ful trick — well worth remembering.
SP contains the number of spaces
PRACTICAL COMPUTING September 1979
| GRAPH OF TRIANGLE WAVEFORM
ike Gf i fu eH
Figure 3.
which must be printed between the
X-axis line and the graph point. The
PRINT function SPC() can be used on
the Pet screen. It moves the cursor X
places to the right, and is much faster
than printing-out spaces in a FOR-loop.
Due to a Pet Basic bug, referred to in
the manual and certainly present in the
earlier Pets, in which SPC(O) is incor-
rectly handled, the special case SPO
must be treated separately (3140-3160 or
4210-4230).
Our Pet-to-printer interface is a mic-
Toprocessor simulating the IEEE to
RS232 converter. It has its eccentricities
but it handles the cursor control charac-
ters produced by SPC(). If yous use an
interface which does not map these
characters, subroutine 8000-8040 has the
same effect, but using space characters.
CH contains the channel number of the
IEEE printer. It is set initially to four in
Statement 16; change this and every
instance of the channel number will be
LOWER BOUND = -130
UPFER LIMIT = 120
THERE ARE SO FOINTS
7
= x
uz *
= x
= *
= x
ne x
Ea x
= x
= *
= x
= xk
=
= K
= *
altered. As an added precaution against
various ‘time-outs’ in the interface, the
channel is opened and closed each time a
routine using the printer is called.
It is the statements 400 to 600 which
calculate the harmonic content of the
waveform. The process is very simple.
For each harmonic every point in the
waveform is multiplied by a point on a
sinewave in the corresponding place in
the wavelength, and then by a cosine
point.
A cosine wave is always 90 degrees out
of phase with a sinewave of the same
wavelength — one-half PI radians, a
quarter wavelength. The inner loop
(480-520) multiplies each point in the
waveform by the value a sinewave and a
cosine wave would have at that point.
_ For the first harmonic — the fun-
damental — there is one complete sine
and cosine wave. The products are
{continued on next page)
"13
SIUNAUODDRUDUGOUUUGOGUUUUEOOUONSAAUTODOOULOUUUURNERELCUONTOGUNR
HIRE A PET MICRO
FOR JUST £5.00
For personal, educational and small
business use. Hire a PET from £5/day
or £25/week.
Essex Computer
Services
Tel: Canvey 61663 (anytime)
or 61926 (office hours}
TT
@ Circle No. 197
ir.
SUCOUUNGHONCGODAOOTONDUOUORAGUOUHOORTOQGUOUOGODOUGOOOGCE
CODDOCOUDOOORGQEEGEOORRUDGOUUROGUTERDOORDOGQAUCRDUON0
‘Wise POUR Ps CLEONIKC
IF OLY SRSA CPM ON
Courses in
Computing
BSc & BSc (Hons)
COMPUTER
SCIENCE
4 years sandwich or
5 years part-time.
Dip HE in
COMPUTER SCIENCE
2 years full-time or
3 years part-time.
BRITISH _
COMPUTER
SOCIETY PART 1
5 terms part-time.
BSc & BSc (Hons)
COMBINED STUDIES
including Biochemistry,
Biology, Chemistry,
Computing, Economics,
Environmental Science,
Geography, Physics,
Technology.
Details from the
Secretary, Faculty of
Science, The
Poly technic,
Wolverhampton WV1 1LY.
Tel: Wolverhampton; 27371
(24-hour answering service).
@ Circle No. 198
] ~ FULLY-DOCUMENTED
SOFTWARE FOR PET
Usually 2 or more programs per
Pack, or available separately. All
packs supplied complete with cas-
sette and booklet including hints,
BASIC code, program structure and
instructions.
e.g. TAPES pack, from
KIDS pack. £8.95
Mail order only. per pack
SAE for full list to: inclusive.
POSSET SOFTWARE
Dept. P1, 14 Slade Rd.
Portishead, BRISTOL,
BS20 9BS.
Hutt
@ Circle No. 199
114
(continued from previous page)
summed into CS and SS. BN is an indi-
cation of how much cosine component
there is in the waveform at the fun-
damental frequency, and AN how much
sinewave component. Inherent in this
pair of numbers is the phase angle, and
the harmonic is often interpreted as hav-
ing so much sine component and so much
cosine component. This is sufficient to
describe the harmonic completely.
Always positive
Alternatively, we can use the harmonic
amplitude — the square root of the sum
of these two components squared
(HA = SOR (AN*AN+BN*BN)) and
the phase angle — the arctangent of
AN/BN. The harmonic amplitude will
always be positive, as there cannot be less
than zero harmonic amplitude. The phase
angle will always be in the range of ~ PI
radians to +PI radians.
This process is repeated, so that each
sample point is multiplied by points gen-
erated as though there are two complete
sine and cosine cycles in the wavelength.
Figure 4.
HARMONIC CUNTENT OF TRIANGLE WAVEFORM
HARMONIC VALUE
1
+
3
2 *x
+
+
SREKKEKEK
+
GRIGIO OOOO IO IOC IO OIOIGIOIDIOIOIOIGIO IOI RIK
This gives the sine and cosine com-
ponents, the harmonic amplitude and
phase angle for the second harmonic.
Then with three cycles, and four, and so
on.
The variable DG is used to determine
how many harmonics will be tackled.
With DG set to 10 (statement 20) a har-
monic series up to one-tenth of the
number of sample points will be pro-
duced — i.e., five harmonics for 50
points, 15 for 150.
If DG is reduced more harmonics are
computed for the same number of sample
points. It should not be reduced to one, as
then only one point would be sampled in
each cycle of the highest harmonic and
the result would be meaningless.
The graphs show a sample containing
50 points and the harmonic charts show
one containing 150 points. There is no
particular reason for this discrepancy,
except that it looks better that way.
Distorted
Figure 6 shows what the numeric table
output looks like for a clipped sine-wave.
Note that although this example contains
PRACTICAL COMPUTING September 1979
GRAI: IF CLIPPED SINE WAVEFORM
LOWER BOUND = -85
UFPER LIMIT = 85
THERE ARE SO FOINTS
=
a
=
=
=
i
ai fi
io ti
aoa i @
t off
Yi ion ii
RMAMHRMHHR HE
tii
*
ht i i Ww #
Figure 5.
‘harmonics, there is no cosine component
— they are all very close to zero. This is
hardly surprising, as it is only a distorted
sine-wave, computed with the Basic
SIN() function.
The last stage in the Fourier analysis of
the chosen waveform is to print-out the
bar chart of the harmonics. Subroutine
6000 displays a series of lines of stars on
the screen, one for each harmonic pro-
duced. The bars are normalised so that
the harmonic with the most power
(greatest amplitude) stretches right
across the screen and all the others are
some percentage of this.
Subroutine 7500 finds the largest value
in HB and puts it into MX. HB contains
all the values of the harmonic amplitudes,
HA, as they are produced. SP contains
the number of stars which will represent
the harmonic (6030 or 7070). A FOR-
loop is set to print-out the stars (6040-
6060 or 7080-7100).
PRACTICAL COMPUTING September 1979
MMH HHH HHH HK
The printer routine has a few extra aids
to improve the layout. For instance, there
are two blank lines between each of the
bars, thus increasing legibility many times
(7024-7040).
The harmonic number is printed. It is
unfortunate that the printer interface did
not like the use of a comma as a tabulate
function in the PRINT statement.
Because of that, subroutine 8100 was
written to print a number padded-out to
10 columns with spaces.
This is also something of a cunning
trick; convert the number to a string with
STR&(), concatenate 10 spaces, and then
print only the first 10 characters of the
resulting string using LEFT3().
Fourier analysis is used widely
throughout the engineering sciences to
examine sounds and vibrations. Every |
building or bridge has its own natural
(continued on next page)
NICOMTECH
Cornish and West Devon distributor for
the ITT 2020 and range of accessories
Amateur radio software available for PET,
APPLE, 2029 and TRS-80
European Distributor for MICROTRONICS
MORSE and RTTY software for PET and
TRS80O
Blank C10°2 etc. on sale
Mailing services available
Phone N:gel Huntley on (075-55) 2066.
Address: 212, St. Stephens Road,
Saltash, Cornwall.
@ Circle No. 200
POWER
B lA SUPPLIES
FOR SYSTEM 64K EXPANSION
BIAS 1 for general micro use
+5v @ 10amps +12v @ 2amps
—5v @ lamp KIT £37.04
BIAS 2 for analogue /peripheral use.
+ 12v to 25v @ 3amps.
Adjustable. KIT £32.41
BIAS 3 for S100 systems
+ 8v @ 10amps
+ 18v @3 -Samps. KIT £35.19
Over Voltage Protection — optional
B1 — £12; B2 — £7; B3 — £9
HEAVY ALLOY CASE 150x150 x200
includes switches, connectors, predrilled £12
Assembled & Guaranteed add £10
— —=
Mail order to: TOOTING COMPUTING
157 ROBINSON ROAD
p&p LONDON SW17
£2.50
Tel: 01-543 1398
@ Circle No. 201
CASH & CARRY
* PET 2001 8K & 32K
* PET Serial Interfaces
* PET Parallel Interfaces
* PLESSEY 24(32)K Memory
*“ CENTRONICS 779 Printers
Also some ex-demo/hire units available.
(with full warranty).
Phone John Handy, 042 050 374.
@ Circle No. 202
15
TOPMARK
Computers
dedicated to
APPLE II
Simply the best!
Full details from Tom Piercy on
Huntingdon (0480) 212563 or circle
enquiry card.
@ Circle No. 203
SORCERER
in the
MIDLANDS
contact
Midland Microcomputers
Nottingham (0602) 298281
for all your hardware and
software requirements
@ Circle No. 204
Computer Supplies
TANDY
£462.00
£535.20
£581.50
£655.00
£415.75
£925.00
£1,045.00
£212.00
£331.50
£460 4K
£550 4K, level Il
£675 16K
£795 16K, level il
£795 Disc Dnve
£645 Roll Panter
£55 Trac Pnnter
£ 99.50Zero interface
£ 5.3016K Interface
Twin Discs
Pnnter
Cassette Deck
Kim 1
Dust Cover
RentaPet from £20 weekly. All prices
show ex-VAT. Petsoft and Petact
dealers. Tailor-made systems and
software. Quotations for your
business or educational needs from:
Radio Supplies Ltd
80 Gower Road, Sketty.
Telephone: Swansea (0792) 24140.
@ Circle No. 205
116
HARMONIC NUMBER 1 .
2£.56050262E-07 SINE COMP=
cos COMF=
HARMONIC AMPLITURE=
PHASE ANGLE=
93. 2256294
2.74656512E-09
HARMONIC
COS COMF=
HARMONIC AMFLITUBE=
PHASE ANGLE=
NUMBEK 2
1. 2539581E-07
. 077588509
HARMONIC NUMBER 3
COS COMF=
HARMONIC AMFLITUDE= 5.
PHASE ANGLE=
28212876
. 24086318E-08
HARMONIC NUMBER 4
COS COMF=
HARMONIC AMFLITUDE=
PHASE ANGLE= -. 325458277
HARMONIC NUMBER 5
COS COMP=
HARMONIC AMPLITUDE= 2.98098795
PHASE ANGLE= -9. 15510039E-09
1.18365278E-07 SINE COMP=
4,.56365524E-08 SINE COMP= -1.
1. 42728838E-07
2.72912439E-08 SINE COMP= -2.
93. 2256294
-9.7195S1522E-09 SINE COMP= ~1.25018546E-07
un
hm
@o
i]
=
nN
o
N
cA
35236187E-07
98098795
HARMONIC CONTENT OF CLIPFED SINE WAVEFORM
HARMONIC VALUE (LOG)
1 #81 IOI IIIT OT IIIT I ITI ITI III
2
+
2 e
’
+ :
3 4k OGIO IO IO IOI IOI IOI OK
+
+
4 $k
+
€
te) SOO KOK
2
+
Figure 6.
(continued from previous page)
resonant frequencies, since it is imposs-
ible and undesirable to make them totally
rigid. Cracks and faults can be detected in
such things as pipes and locomotive
wheels by the way they ring when tapped.
The defects will cause different har-
monics to appear; this is not to say that
there are not more direct methods of test-
Ing.
High accuracy
An analogue-to-digital converter could
be added to this program to enable the
user to analyse many waveforms. For
instance, the clipped sinewave could have
been produced by an audio amplifier
under test. It shows that the amplifier has
saturated, and has produced harmonic
distortion, primarily the odd harmonics.
It must be realised, however, that results
obtained with these waveforms are an
ideal, produced to high accuracy by the
internal SIN() function. Real digitisation
will upset the results by introducing
spurious harmonics.
For those who wish to experiment with
the program, try the ramp waveform,
since it should contain all harmonics,
both odd and even. A pure sinewave will
produce only one harmonic bar, at the
fundamental frequency.
Try also placing a sheet of transparent
graph paper over some oscillograms and
inputting some real waveforms using the
““O” option.
In a later part of this article some
further waveforms will be analysed,
including a pulse and pseudo-random
noise. Further, having dissected a
waveform in this way, it is possible to |-
reconstitute it.
In practice this is like dismantling a
complex mechanism — there is always
something left over which should have
been included. By using only some of the
constituent harmonics, the effect of a per-
fect filter can be investigated. Those
familiar with imperfect audio filters will
notice the difference. In any case, we will
continue to ignore such wonders as the
fast-Fourier transform and vast amounts
of mathematical theory.
PRACTICAL COMPUTING September 1979
DEES) OO
10 REM DICTIONARY
12 REM AN - COSINE COMPONENT
14 REM BN ~- SINE COMPONENT
16 CH=4: REM PRINTER CHANNEL
18 REM CS ~- SUN OF COSINE
20 [G=10: REM HARMONIC INTERVAL
ee REM OX ~ SINE INTERVAL
24 REM FG - A FLAG
26 REM HA ~ CURRENT HARMONIC AMPLITUDE
28 REM HBECNO) ~ HARMONIC AMFLITUDES
30 REM HIIt - WAVEFORM NAME
$2 REM I - LOOP COUNTER
34 REM J - LOOF COUNTER
36 REM K ~ LOOF COUNTER
38 REM L - LOOF COUNTER
40 REM MN - MINIMUM VALUE IN ARRAY
2 REM MX ~- MAXIMUM VALUE IN ARRAY
44 REM NO ~ NUMBER OF FOINTS IN SAMPLE
46 REM OF - OFTION SELECT
48 REM F - NUMBER OFHARMONICS
SO REM FPA - PHASE ANGLE
$2 REM FR - O IF NOFRINT, 1 OTHERWISE
34 FW=70: REM PRINTER WIDTH
S46 REM SF - SPACE/BAR LEHGTH
S@ REM SS - SUM OF SINE LOCATIONS
60 REM TM - TEMPORARY LOCATION
62 REM WYVCNO) ~ FOINTS IN SAMPLE
64 REM Y$ - YES/NO OFTION
100 FRINT'FQURIER ANALYSIS FROGRAMN”
Pa® PF ROLIN @ sesecnecSosces) sec icc ee ieee
L20 INFUT"HOW MANY SAMPLE FOINTS"; NO
130 IFNODLIOANDINOCSSSTHENISS
140 FRINTNO:; " OUT OF RANGE —- TRY AGAIN"
130 GOTO120
155 NIM WYVCNO),HBECNOD
ao FRLNT ” gma SET OFTION"
170 FRINT"O INFUT WAVEFORM FOR ANALYSIS"
180 FRINT*1 - FOR SINE WAVE"
190 FRINT'2 - FOR SQUARE WAVE"
200 FRINT'S3 - FOR TRIANGLE WAVE"
210 FRINT'4 - FOR SAWTOOTH WAVE*
220 FRINT'S - FOR CLIPFER SINE”
230 INFUT’OF TION’; OF
260 TF OF C30 THEN290
270 GOSUR 1000
280 GOTO0330
290 IF OF OANTD OF CSTHENS2Z0
300 FRINT*NO SUCH OF TION - TRY AGAIN"
310 GOTO160
320 ON OF GOSUB1100, 1200, 1300, 1400. 1500
330 INFUT"EO YOU WANT A FET GRAFH": Y%
340 IF Y#="YES"THEN GOSUB3000
350 INFUT*DOYOU WANT A FRINTER GRAPH"; Y%
360 IF Yt="YES" THEN GOSUR4000
370 FR=0
480 INFUT*IO YOU WANT RESULTS TO FRINTER';
390 TFY$="YES* THEN FR=1
400 REM 10 THE HARMONIC ANALYSIS
410 REM INTERVAL DEGREE
420 FP=INTCONO/EG)
430 FOR [=iT0O F
440 TiX=2*3.14159263/N0
(continued on next page)
PRACTICAL COMPUTING September 1979
YR
double sided/density
Available from stock
at competitive prices.
5%" and 8" single and |
Z
P a
77
|
VA
Soo]
Also ail other computer media and supplies, including
Cassettes Storage Systems
Ribbons Computer Files
Print Wheels Stationery
Lo F J
Michae! Collins Computer Suppties Limited.
52, Canbury Passage, Kingston, Surrey
Telephone: 01-549 9441
@ Circle No. 206
NEW LOW OHIO
PRICES
4K Superboard £245
8K Superboard £287
Challenger IP £360
Challenger IP with mini floppy £1,050
Extra mini floppy drive £385
610 expansion board with 8K £265
All prices exclusive of VAT
Please send SAE for details
CTS 1 Higher Calderbrook,
Littleborough,
Lancs., OL15 ONL,
Tel: Littleborough
(0706) 79332 any time.
@ Circle No. 207
| 30 St. Johns Road,
Tunbridge Wells,
(STD 0892) 39591.
| Digital Microsystems DSC-2 Low Cost
Computer System incorporates
@ 1 Megabyte of Floppy Disc storage on two
@ single sided 8in. Shugart drives
@ 64K bytes of Main Memory Standard 32K or
@ 48K available
@ CP/M Disk Operating System ee TEXT
PROCESSING BASIC—COBO)
FORTRAN available
EXPANDABLE—Add on Hard Disk System up to
28 Megabytes per drive
MODATA ARE LOOKING FOR
DEALERS AND DISTRIBUTORS
@ Circle No. 208
Intex Datalog Limited,
Eaglescliffe Industrial Estate,
Eaglescliffe,
Cleveland TS16 OPN.
Telephone (0642) 781193
Stockists of Commodore and Petsoft
software also accessories for your
PET MICROCOMPUTER
For instance:—
Pet Dustcover £6.00
Pet Head Demagnetiser £4.00
Prices include VAT but please add 50p
per item for post.
—
@ Circle No. 209
117
AfOfcomne
HELP YOUR MICRO
TO HELP YOU
* Micro-computers and
peripherals
* Feasibility studies
“Machine evaluation and
selection
* Systems to your requirements
* Software packages
* Books
For our PROFessional COMPuter
advice, service or products, write or
phone:
Profcomp Ltd., 107 George Lane,
London E18 1AN 01-989 8177
@ Circle No. 210
EXIDY SORCERER
32K Micro Computer
£859.00+ VAT
Dealer for
Bristol and
South West
ELECTROPRINT (Mr. Tasker)
5 Kingsdown Parade « Bristol6 « 292375
@ Circle No. 211
ANNOUNCING. ...
A ONE DAY INTENSIVE COURSE
tneluding: Baste Programning, Systems,
Flaw-Charting, Machine Code, eic.,ete.
(50% of progrurming time spent
actually using mtcro-computers)
Date: 16 OCTOBER 1979
Venue: EUROCREST HOTEL - WEMBLEY
Price: £ 34.50 (ine: LUNCH & VAT)
LIMITED NUMBERS: FIRST COME
PROGRAMMES & APPLICATION FORMS FROM
L & J Computers
3 CRUNDALE AVENUE KINGSBURY
NW9 9PJ
LONDON
01-204 7525
@ Circle No. 212
fully assembled
burned in $100
£198
250ns £271
450ns £266
250ns £506
450ns £470
Dyna-Byte
16K Dynamic RAM
16K Static RAM
16K Static RAM
32K Static RAM
32K Static RAM
80 - 24 video terminal, just add key-
board and monitor £177.
Cable set for videoterminal £7°20
Postfree. Add VAT toall prices.
§.W.C. Electronic distributors, P.O.
Box 30, London E.4.
@ Circle No. 213
118
(continued from previous page)
450
4640
470
480
ASO
300
210
s20
130
340
wo0
360
4170
380
u8S
390
| 600
610
42
630
540
63
460
FRINT'COS COMF=
CS=0
S§=0
REM THE SUMMATION
FOR J=i TO NO
a ee ee ae eo oo
CS=CS+WV¢ J) kCOSCTM)
SS=SS+WV( J) *xSINCTM)
NEXT J
REM COSINE
AN=2*CS/NO
REM THE SINE
BN=2X%SS/NO
REM HARMONIC AMPLITUDE
HA=SQR( CANXAN) + CBNXEN ) )
HE(1)=HA
COMPONENT
COMPONENT
REM FHASE ANGLE KETWEEN AN ANI! BN
FA=ATNCAN/BN)
FRINT"HARMONIC NUMBER
"|; AN: "
FRINT"*HARMONIC AMFLITUDE=
“30
"i HA
PRINT'FHASE ANGLE= °: FA
FRINT
IF FR=1 THEN GOSURS000
NEXT I
FG=1.
SINE COMF=
"; EN
INFUT"DO YOU WANT HARMONIC CHART ON FET": Y%
IF Yé="YES" THEN GOSUB6000
INFUT"TIO YOU WANT CHART ON FRINTER': Y%
IFY$="YES" THEN GOSUB7000
IF FG=0 THEN STOF
FG=0
INFUT "EO YOU WANT LOGCAMPLITULIES) ° ¥%
Me TSC VES
FOR I=1 TOF
HR¢ DT) =1.OGCHE(T))
NEXT J
GOT0630
REM INFUT WAVEFORM FOINTS
INFUT"NAME WAVEFORM’: HIS
FRINT' THERE ARE °;NO;° FOINTS
FOR I=1 TO NO
FRINT*INEUT FOINT
INFUT WYVC(T)
NEXT 1
THEN STOF
wiles
RETURN
REM GENERATE SINE WAVE
HIie="SINE WAVEFORM"
FORI=17TO NO
WYCTI=SINCI/NOKS. 28318531) k100
NEXT I
RETURN
REM GENERATE SQUARE WAVEFORM
Hid="SQUARE WAVEFORM!
TM=NO/2?
FOR T=1i1 TO TM
WV(I)=-100
NEXT I
FOR t=TM TO NO
WV¢(1)=+100
NEXT I
RETURN
PRACTICAL COMPUTING September 1979
TO BE ENTERED"
» HE¢="CLIFFED
REM GENERATE TRIANGLE WAVE
HOosé=" TRIANGLE WAVEFORM"
TM=0
FOR I=1 TO INTCNO
WUC T)=TM
TM=TMt10
NEXT If
FOR J=I TO
WYCJ)=TM
TM=TM-10
NEXT J
FOR I= J TO NO
WVCT)=TM
a0)
INT CNOK. 75)
~ TM=TM+10
NEXT If
RETURN
REM GENERATE SAWTOOTH WAVE
HiS="SAWTOOTH WAVEFORM"
TM=-NOKS
FOR [=1 TO NO
WYVCT)=TM
TM=TM+10
NEXT I
RETURN
REM GENERATE CLIFFEN
GOSUR 1100
FOR I=i TO NO
IFWVCT)S8STHEN WUC T)=85
IFWVCI)C-85 THEN WUC T)=-8%
NEXT I
SINE WAVE
SINE WAVEFORM”
RETURN
REM FRINT GRAFH OF WAVEFORM
REM IN WV ON PET SCREEN
FRINT "GRAPH OF "3 HI
GOSUBR 4500
PRINT "LOWER
FRINT "URFFER
PRINT *"THERE
FORI=1T039
PRINT °#°;
NEXT I
PRINT
FOR I=1 TO NO
FRINT*#°;
TW=MX~MN
SP=INT CC CWVUCTO-MND/TWKS6)40. 5)
IFSP SOTHENS170
PRINT" Xk"
GOT03180
PRINT SFCCSP); "x®
NEXT I
RETURN
REM FRINT GRAFH OF WAVEFORM
REM IN WV ON EXTERNAL PRINTER
OPEN CH,CH
GOSUB 4500
FPRINT#CH
FRINT#CH
FRINT#CH, "GRAPH OF
FRINT#CH
FRINT#CH, "LOWER BOUNT =
BOUND "i MN
LIMIT "i MX
ARE "; NO; "FOINTS"
it ou
*; HDS
*;MN
PRACTICAL COMPUTING September 1979
(continued on next page)
WANTED: TRS-80
PROGRAMS
Business, games,
programming aids, scientific
or any application. Outright
purchase or generous royalty
payment.
Send your tapes to:
Dataplus,
67 Bridge Street,
Manchester M3 3BQ.
@ Circle No. 214
IF YOU NEED. .
HIGH SPEED CASSETTE
PROGRAMME DUPLICATION
AND THE SUPPLY OF TOP
QUALITY CASSETTES ...
Why not ring us on 01-399 2476/7 and let us
quote you for your next requirements.
MEDIATAPE LIMITED, 29a Tolworth
Park Road, Surbiton, Surrey.
01-399 2476/7
@ Circle No. 215
COMPUTERS
FOR BUSINESS
We understand what is needed trom a
computer. Our comprehensive
turnkey service provides a versatile
computer system with packaged or
bespoke commercial software, at very
reasonable prices. Evaluation, design.
installation and full on-site training.
Ring Richard Mortimore at
MICRO-FACILITIES, 01-979 4546,
for free survey or demonstration. 127
High Street, Hampton Hill,
Middlesex.
@ Circle No. 216
HUMBERSIDE
MICROPROCESSOR SERVICES
THE COMPLETE
INDEPENDENT SERVICE
Application areas:
Business, process control, education,
Personal Computing
e can provide for you:-
Consultancy, training, supply,
maintenance and software to suit
your individual requirements
Including
Commodore PET
M6800
Compec 202
and full ancillary equipment.
Microprocessor Services,
139 Beverley Road,
Hull
Humberside.
For further details ring (0482) 23146
@ Circle No. 217
119
ROCKWELL AIM 65
Now in 3 important ways
1. AIM 66 (ex-stock)
Comes complete with display,
printer, ao monitor in —
and 4K RAM 310
2. AIM esc (30 days)
Has everything in item 1 plus 4K
Assembler desk-top case and
power supply unit £475.
(8K Basic interpreter can be
substituted for £10 more.)
3. PDS 66. (30 days)
The truly portable version of AIM
with 4K RAM, 4K Assembler, 8K
Basic, portable carrying case and
power supply unit. from £750.
All the above prices include the
extensive Rockwell documentation
but are exclusive of VAT.
Forby House,
18 Market Place,
ee tems Brackley, Northants.
Limited phone 0280-702017
telex ‘Micro’ 83147.
@ Circle No. 218
COMPUSTAT
Continuous Stationery
for the Micro Computer
All sizes of listing paper stocked.
Specialists in the preparation of
Printed continuous stationary
AD
U
Design Service available
Spacing Charts £1.00 C.W.O.
Commercial prices to all.
Phone or write fora
quotation to Miss Berry.
01-520 6038
63 ORFORD ROAD,
LONDON, E.17
@ Circle No. 219
AA WUAMAAUAAUNLUALNNTUADNANAUOLUAUONDONUOGDEENG LS OONUU AEE OTN U PAU ST ENTE
TRS-80 SOFTWARE
We have the largest TRS-80
Program Library in the country.
Business, finance, scientific and
games. LEV11 and DISK.
New programs daily. We pay good
prices for original programs.
S.A.E. for lists to:-
MICROCOMPUTER
APPLICATIONS
11 RIVERSIDE COURT,
CAVERSHAM, READING
RG4 BAL.
STUAVUUDNUAAUCONOOONV ND OOGNUNUOGUOOGDOLSODNOGUOULOGNONGNODEONOLANUODNOEIOOL FE
®@ Circle No. 220
UEUOQUUEUENUUCUOTECUNOLCEOONOROLOEUGUCAAAVANSBOTEOCUNNDAUOCL OT ASS
VUDSUUDYROVROELOUEDODASNUDONAUGLODOUSUOTEOTUUTAUALOLOUSEOTEOOUULD
pT]
(continued from previous page)
4080
4090
4100
4110
4120
4130
4140
4150
4160
4170
4180
4190
4200
4210
422
230
4240
290
260
4270
“4500
4501
43510
432
43530
4340
43550
4360
43570
7000
wO10
5020
9030
9040
3050
31060
2070
3080
6000
6010
6020
69030
5040
6050
4060
6070
6080
6090
7000
7010
7980
7022
7024
7026
7030
7035
7040
7050
7055
7060
7070
7080
7090
7100
17105
PRINT#CH, "UPPER LIMIT = *; MX
PRINT#CH
PRINT#CH, "THERE ARE *; NO; * POINTS".
PRINT#CH
PRINT#CH
FORI=1TOFW
FPRINT&CH, "= *;
NEXT I
FRINT#CH
FOR I=1TONO
PRINT@#CH, "= °3
TW=MX~MN
SF=INT(( (WUC L)=MN) /TWKEW) +0. 5)
IF SP0 THEN4240
FRINT#CH, *X"
GOTO4250
PRINTS@CH, SFC(SE) 5 8x"
NEXT I
CLOSE CH
RETURN
REM FINE LAGEST (MX) AND SMALLEST
REM (MN) VALUES IN WV
MX=WV (1)
MN=WV( 1)
FOR I=2TONO
TFWVCI) MXTHEN MX=WV(T)
IFWVCIT)CMNTHEN MN=WVCT)
NEXT I
RETURN
REM PRINT RESULTS ON PRINTER
OPEN CH,CH
PRINT#CH :
PRINT#CH, "HARMONIC NUMBER®*; J
FPRINT#CH, "COS COMF= "; ANi*® SINE COMFP= °; KN
PRINT#CH, "HARMONIC AMPLITUDE= *°; HA
FRINT#CH, "PHASE ANGLE= °3 FA
CLOSE CH
RETURN
REM PRINT HARMONIC BAR CHART ON FET
GOSUB7500
FOR K=1TO F
SF= Re eee) NX) RSE IRON 3)
REM PRINT HARMONIC BAR CHART ON FRINTER
GOSUBR7S00
OFEN CH, CH
FRINT#CHs “HARMONIC CONTENT OF "> HII%
FRINT#CH
FRINT#CH
PRINT#CH, "HARMONIC VALUE *5
IF FG=0 THEN FRINT#CH,* (LOG)*"
FRINT#CH
FOR I=1 TO F
GOSUB8100
FRINT#CH, *# °;
SP=INT((CHRCT)/MX) KC PW-10) 40.5)
FOR J=1 TO SF
FPRINT#CH, *X "3
NEXT J
FRINT#CH
PRACTICAL COMPUTING September 1979
7110
7120
7140
7150
- 7160
73500
7310
7320
7530
7940
7350
8000
8010
FRINT#CH, *
PRINT#CH, *
NEXT I
CLOSE CH
RETURN
REM LARGEST VALUE
MX=HE(1)
FOR K=2 TO F
NEXT K
RETURN
FOR K=1 TO SF
8020 FRINT#CH. " "5
8030 NEXT K
8040 RETURN
8100 REM PRINT NUMBER
8101 REM IN 10 COLUMNS
8110 FRINT#CH, LEFTS(STRS(T)+"
8120 RETURN
RE ATVY
IN HE
TO MX
IF HB¢CK) SMX THEN MX=HBCK)
REM FRINT SF SFACES TO THE PRINTER
IN J ON PRINTER
=, LOD);
o
Hotting-up in the
16-bit war
THIS COULD well be described as the year
of the 16-bit microprocessor with devices
due or already available from all the
major semiconductor manufacturers.
Single-chip 16-bit microprocessors are
not, of course, new, since devices like the
Texas Instruments 9900 and the General
Instruments 1600 have been around for
several years. What makes the new
devices different is their power . and
memory addressing capabilitv. writes’
Nick Hampshire.
While the 9900 can address 64K bytes
of memory, the Z-8000 can address 8
megabytes. The new devices are the 8086
from Intel, the Z-8000 from Zilog and
the MC68000 from Motorola. Of the
three devices, the first two are already
available and the MC68000 is scheduled
for this month.
Intel first |
The first of the new 16-bit mic-
roprocessors to reach the market was the
‘Intel 8086, which is available both as a
component and as a prototyping system
(the iSBC 86/12). Probably the most sig-
nificant feature of the device is its use of
dual-processor architecture to produce an
advanced pipe-line machine.
Pipe-lining is a process in which the
next instruction is fetched while the pro-
cessor is still executing the previous one.
The dual-processor architecture of the
8086 does this by having one processor as
the execution processor and the other as
the bus interface and instruction fetch
Processor.
The Z-8000 has just reached the mar-
ket in volume and is claimed by Zilog to
be more advanced than the Intel 8086 —
1a claim which only time and user experi-
PRACTICAL COMPUTING September 1979
ence will verify. There are two versions of
the Z-8000. The Z-8002, the smaller ver-
sion, is capable of addressing directly just
one megabyte of memory and the Z-8001
can address a full eight megabytes of
memory.
High speed
The Z-8000 is best described as a gen-
eral register machine, which, like the
8086, incorporates dual processor pipe-
lining to obtain high speed of execution.
The processor has 16 16-bit registers
which can be subdivided logically into 16
8-bit registers, eight 32-bit registers and
four 64-bit registers, giving a high degree
of symmetry to the architecture and offer-
ing the user great flexibility.
All the 8- and 16-bit registers are
general-purpose accumulators and 15 of
them can also act as index registers.
There are two pairs of stack pointers, one
containing the address and the other the
segment number.
The reason for two pairs is that the
Z-8000 has been designed to support
multiprocessing and can run both a
supervisor and user program con-
currently by using one stack pointer for |:
the supervisor and the other for the user.
There is also a 64-bit status register
which contains the flags, control bits and
a 32-bit program counter. So that the sys-
tem can use dynamic memories easily, a
rate-programmable refresh counter is
included as one of the registers.
There are 115 instructions in the
Z-8000 instruction set and, like the 8086, |
many of them more closely resemble |.
high-level language instructions than |:
those found on the current generation of |,
8-bit micros.
NASCOM SOFTWARE
FOR EXPANDED SYSTEMS (8K upwards).
Level C Basic — Full Floating Point Arithmetic.
Supplied on cassette £12.50 or in 4x 2708 Eproms
£42.00.
Debug with Superstep — for machine code
debugging £5.00.
Relocator — relocates and re-addresses machine
code programs £4.00.
Octal Loader — handles true and split octal £3.00.
Superstartrek — runs using Level C Basic £4.50.
Superstartrek — runs using Nascom’s 2K Basic
£4.50.
FOR STANDARD SYSTEMS
Level A Basic Insert in place of your monitor Eproms.
Supports ALL normal Tiny Basic commands.
Supplied in 2x 2708 Eproms £21.50.
ALL products are fully documented.
CCSOFT (Southfields)
83 Longfield Street, London SW18
Tel: 01-870 4891
@ Circle No. 221
B&B Consultants
THE CONSULTANTS FOR THE
NORTH WEST
“You can rent me for 10 pence an hour”’
For further details please contact
B&B CONSULTANTS
124 Newport Street,
Bolton, Lancs.
Or Telephone: Bolton
(0204) 26644
At:
@ Circle No. 222
MANAGER/PARTNER
required
for new microcomputer
shop opening in Dublin.
Must be dynamic and
enthusiastic. Some
experience with
microcomputers would be
helpful.
Good salary and prospects.
Box No. 389.
PROGRAMMERS
Experience of
Micro-Systems. Well-paid
full- and part-time work.
Developing programs for
Euro-cust.
All details of c.v. to;-
ETAG, 14 Elstree Road,
Hemel Hempstead.
120 |
ry
&
Exidy Sorcerer
Full range of hardware and software,
including the new Professions! Word
Processing ROM/PAC. Business sys-
tems including printer, dual disc
drives and professional quality VDU
for around
£3,200 + VAT
Now available
MICROSTOCK
Microstock stock recording package
for the Sorcerer offering facilities usu-
ally found only on large machines,
e.g., instantaneous access to item
details.
Package cost £120 + VAT or send £5
for manual only (allowed against
future purchase).
Mike Collier
Basic Computing
Oakworth Road,
Keighley, W. Yorks.
Tel: Keighley (0535) 65094.
ir
STAVNUUbeseuetnenencencncoceaanccecncocannscccasoagageiegggiite,
@ Circle No. 223
COMPUTECH FOR
APPLE SYSTEM.
APPLICATIONS
SOFTWARE
Professional business software packages
now available are turnkey systems with
comprehensive manuals, built-in validity
checks, interactive enquiry facilities, user
options, satisfying accountancy, Iniand
Revenue and Customs and Excise
requirements on diskette with DOS space
ab2s
Not adaptations, written specifically as
packages for the Apple System.
COMPUTECH SYSTEMS
168 Finchley Road, London, NW3
GHP. Tel: 01-794 0202.
Dealer enquiries welcome.
@ Circle No. 224
MICROTEK
COMPUTER
SERVICES
—
Agents for North Star Horizon.
Personalised software for small
business applications. Stock
control, budget control, client
information, VAT and
accounting packages.
50, Chislehurst Road,
Orpington, Kent
Tel 66-26803
evenings 0474-872630
@ Circle No. 225 .«
122
BUYERS’
GUIDE
If a computer has been reviewed by
Practical Computing, the date of the
appropriate issue is indicated.
ACORN COMPUTERS
Acorn. Single Eurocard-sized microcomputer with 6502 processor,
1KB RAM, 16-way I/O. Max size: a second Eurocard adds hex
keypad and CUTS cassette interface. Monitor and machine-code
programming now. Basic and disc operating system in the future.
“Highly cost-effective basis for a computer or an industrial
development system”. Available from Acorn (0223) 312772 or
Microdigital (051) 236 0707.
APPLE COMPUTERS
Apple II. Min size: 16K memory; 8K ROM; keyboard; monitors; mini
assembler; colour graphics; Pal card; RF modulator; games; pad-
dles and speakers; 4 demo cassettes. Max size: Expandable to 48K
memory; floppy discs and printers are now available. Two ver-
sions of Basic, PASCAL; Assembler; games; business packages.
An American system regarded as suitable for any kind of applica-
tions. Maintenance contracts offered. Personal Computers Ltd (01-
283 3391) is the sole U.K. agent but has a distributor network of 20
dealers. (Reviewed July, 1978.)
ATTACHE
Attache. Min size: system with 10 slots, $100 bus, 8080 processor
and 16KB housed in desk-top case with built-in keyboard. Max size:
64KB, parallel printer interface, two single- or double-density 8in.
floppies, video screen. Disc Basic; business applications produced
by Moncoland, the sole U.K. agent. Distributors include Keen,
GBH, Alba, and Lion.
BRUTECH ELECTRONICS
£74.75 kit, £96.25
assembled
Around £1,000
‘From £1,737. Full
business system
about £5,000
BEM-CPUI: Single-board processor with 6502 and noRAM. Applica- £133 exe VAT
tions software. Available from Data Precision Equipment (04862
67420). (Reviewed March, 1979.)
Microbox. Chassis with three to six PCB sockets for $100 boards, £255
plus fan. Several S100 boards available. Aimed mainly at OEM
industrial users and perhaps the serious hobbyist. It will take
Cromemco, North Star and other processors. Available from Com-
art (0480 215005).
COMMODORE SYSTEMS DIVISION
Pet. Single unit containing screen, tape cassette and keyboard.
Floppy disc, printer and fulldine 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 dis-
tributors.
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 hob-
byist but used mainly as an evaluation board for the 6502 chip.
Twelve to 15 dealers. (Reviewed October, 1978.)
£460-£795 exc VAT
£99.95
PRACTICAL COMPUTING September 1979
COMPELEC ELECTRONICS |
Series 1. 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 is also sole supplier
of Altair systems.
COMPUCOLOR
Compucolor II. Packaged system including 13in. eight-colour dis-
lay with alphanumerics and graphics, 72-key detachable
eyboard, 8KB, and built-in mini-floppy. Max size: 32KB. Extended
disc Basic in ROM, graphics programs and games. The system
now ranks fourth behind Pet, THS-80 and Apple in personal compu-
ter sales. Abacus (01-580 8841) is sole U.K. agent and is arranging
ae on including the Byte Shop and Transam. (Reviewed
une, ;
COMPUCORP
610: desk-top unit using Z-80 and incorporating screen, 150KB
floppy, 48KB. Up to 60KB memory, four floppies, printers. Basic,
Assembler, DOS, text editor, file manager; business packages.
Nine dealers.
COMPUTER CENTRE
Less than £5,000
for basic system
From £1,390
From £3,890
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 connectors.
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/
interpreters and Algol compiler. Microsoft Basic, Cobol, Fortran
also available. Computer Centre (02514 29607).
COMPUTER WORKSHOP
Mini kit: £786
Maxi kit: £886
System 1. Typical size: 40K memory; dual 8in. floppy discs, total
storage capacity 1.2MB; Ricoh daisywheel printer.
System 2. Typical size: 24K memory; dual minifloppy discs of 80K
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.
CROMEMCO
Single-card computer. 4MHz Z-80 CPU, S100 bus, IKB RAM, sockets
for 8K ROM. 20mA/RS232 serial interface and rallel bi-
directional interface. Basic in ROM and Z-80 monitor. For OEM and
industrial users; used with backplane for “full computer capabil-
ity”. Datron Interform and Comart are agents, the latter with 12
distributors. (Reviewed February, 1979.)
Z-2. Min size: chassis, 30A power supply, motherboard, Z-80 pro-
cessor, 16KB memory. Max size: 312RB, 21 sockets, three mini-
floppies or four 8in. floppies. Basic, Fortran, Cobol, assemblers.
For serious hobbyists, OEMs, educational applications, and
industrial/scientific users.
System Two. Min size: factory-assembled system with 32KB, dual
30K minifloppies, dual printer interface, serial interface. Max size:
two additional floppies, 512KB, up to seven terminals. CP/M.
compatible operating system (DCOS), Fortran, Cobol, Basic,
assemblers, word processing, database manager. Multi-user sys-
tem for software development. or scientific/industrial/business
users.
System Two/64. New configuration featuring mini-diskette drives
and 64K bytes memory. Software and applications as System Two.
System Three. Min size: 32KB, dual 256KB floppies, dual printer
interface, 20mA/RS232 serial interface, Z-80 processor. Max size:
two additional discs, 12KB, seven terminals, multi-channel A/D
and D/A interface, PROM programmer. Software as for System
Two. Described as appropriate for small to medium business, sci-
entific and qadneirial “aamae — “rivals minicomputers at more than
twice the price”.
System Three/64. New configuration featuring dual Bin. diskette
drives; Z-80A processor; 64K of 4MHz memory; console and printer
interfaces. Macro Assembler, Fortran [V, Extended Basic, Cobol,
Multi-user Basic.
PRACTICAL COMPUTING September 1979
System 1, £5,000
plus; System 2,
around £3,000
System 3, from
£1,300
£247-£28 1
£372 (in kit form)
to more than
£4,000
£2,294 upwards
£3,050
£3,444 to more
than £10,800
£4,385
APPLE II comes to
SCOTLAND
Why not call and see the
fantastic Apple Il, the finest
micro currently available?
Demonstration without
obligation
We also have in stock the
following top-quality items:
Nascom 1, including all available
expansion.
Division Monitor Kits — If you are
thinking seriously about a monitor
for your micro we have the best.
Beware of cheap imitations which
may use TV tubes. Ours use pro-
fessional quality tubes which we
have on demo. The difference has to
be seen to be fully appreciated. Nine
and 12 inch in stock now. Price £100
+ VAT.
High Speed Tape Cassette Inter-
face. Comes complete with instruc-
tions showing how to interface to
Nascom giving “normal” and high
speed operation. 300, 600, 1200,
2400 baud. At the highest speed this
will load our 8K basic in about half a
minute. Price (Kit) £17.50 + VAT.
8K Tape Basic. The best basic yet
written for Nascom. Fully floating
decimal point. Complete with all
documentation. Price £35.00 +
VAT.
Brand New Product. Chiptester.
Converts Nascom to a super pow-
erful |.C. tester. Plugs into existing
ports. Send now for full details.
Also newly arrived. Totally new
games to play on any standard Nas-
com. Send for full details prices, etc.
Software and Books ideal
for schools and colleges
now available.
STRATHAND
44 St Andrews Square
Glasgow G1 5PL
Tel: 041-552 6731.
Tel orders welcome
Callers welcome Callers welcome
Now on telex 777268
24 Hour Service
@ Circle No. 226
123
A COMPLETE SERVICE FOR
THE SMALL BUSINESS USER
SYSTEMS FROM £4,500
Ring: 01-653 0835 for brochures.
The Croydon-based Micro House
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JRSTAR
7 ‘EQUINOX
Equinox 3600. 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 10MB 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).
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; expandable with Micropolis floppy discs.
Basic, Assembler and Editor; games, word processor. Other pre-
packaged programs plus EPROM pack for your own programs on
cartridges. Factor One is sole distributor for U.K. (Reviewed
March, 1979.)
HEWART MICROELECTRONICS
Mini 6800 Mk Hl. IK monitor; IK user RAM, IK VDU RAM; CUTS.
Upper- and lower-case VDU with graphics option. 128-byte
scratchpad; decoder/buffer; 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.
68008. 16K dynamic RAM; IK Mikbug-compatible monitor; room for
8K 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.
DIGITAL MICROSYSTEMS
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
peas interface. CP/M and Basic included in price. Extended
asic, 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.
IMSAI
VDP 40: 32K or 64K RAM memory; Qin. display screen, standard
keyboard. Two Sin. floppy disc drives; serial 1/O. Full software
support, and packages available for the VDP 42, which has oa
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.
ITT
2020. Identical to Apple Il. 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 pac-
kages. Generally suited to any type of application. Fifteen
wholesalers, including Fairhurst Instruments.
LUXOR
ABC 80. Min size: 35K with keyboard, CPU, 12in. screen and cas-
sette. 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 I/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.
MICRONICS
| Micros. Typical size: IK monitor; 47-key solid state keyboard; inter.
| faces for video, cassette, printer and UHF TV; serial /O, dual para-
llel I/O ports; 2K RAM; power supply. 2K Basic; British-designed
and manufactured system. Claimed to be the cheapest data termi-
nal— a system with an acoustic coupler and VDU for £1,020, Pros-
pective applications for small businesses, process controllers and
hobbyists. Manufacturer is sole distributor (01-892 7044).
@ Circle No. 227 |
£5,000-£40,000 plus
From £760 without
VDU to £1,200 with
floppy discs
From £127.50 plus
VAT
From £275 plus
VAT
From £4,465
£4,507 for 32K
model. £4,950 for
VDP 42
From £827 to
£3,003 for 48K, two
floppies and
printer
£795 plus VAT
From £400,
assembled
PRACTICAL COMPUTING September 1979
MICRO V
Microstar. Single box with twin 8in. floppy 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 Efti-
ciency subsidiary, Microsense Computers, Microsolve is London
agent; other distributors being arranged.
MIDWEST SCIENTIFIC
INSTRUMENTS
£4,950 machine
and software
MSI 6800. Min size: 16K memory Act I terminal; cassette interface.
Max size: three disc systems — minifloppy system with triple drives
of 80 bytes each and 32K memory, large floppy system with up to
four 312K-byte discs and 56K of memory mounted in a pedestal
desk, or hard disc system with 1OMB and S6K. Basic interpreter and
compiler; editor; assembler; text processor on small disc system.
American-designed system being manufactured increasingly in
the U.K. Sole Tk. agent is Strumech (SEED) (05433 4321) but a
distributor network is being established.
NASCOM MICROCOMPUTERS
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 I/O ports. Mostly games, but also a dedicated text editor
system written by ICL Dataskil. Nascom is working on large ver-
sions 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.)
NATIONAL MULTIPLEX
£168 exc VAT
Pegasus. Min size: 48K; Z-80; double-density floppies (320KB); $100
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 edu-
cation, business and home users. London Computer Store (01-388
5721) sole supplier.
NETRONICS
Elf 11: single-board computer in kit form or assembled. RCA Cos-
mac 1802 processor, hex keyboard, 256 bytes RAM; options include
up to 64KB, ASCII keyboard, cassette and RS232 VO, and video
output. Machine code or Tiny Basic. Promoted as a teaching sys-
tem in minimal form, but expandable for more general use. Sole
U.K. distributor HL Audio (01-739 1582).
NEWBEAR
7768. CPU board, 4K memory, cassette and VDU interfaces. Range
of Basics and games, British-manufactured system for hobbyists.
Expandable to 64K memory available only in kit form. From New-
bear; also from Bearbag dealers, Microdigital, Microbits.
NORTH STAR
Horizon. Min size: 16K memory; Z-80A processor, single minifloppy
disc drive (180KB). Max size: 56K memory, four minifloppy disc
drives (180KB), any acceptable S100 peripheral 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 for commercial, educa-
tion and scientific applications. Application software for general
commercial users. Twenty distributors. (Reviewed April, 1979.)
OHIO SCIENTIFIC
£2,700 exc VAT
=——__. “"__ _¥
Basic kit £79.95.
Assembled £99.95.
1/0 board £35
From £5
£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
/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 prog-
rams. This and other Ohio products have six U.K. distributors.
(Reviewed June, 1979.)
Challenger C24P: similar to Superboard but with a 32 x 64 charac-
ter set. Supplied as two separate boards with open slots for expan-
PRACTICAL COMPUTING September 1979
From £298
£343 to £1,204
INTERFERENCE?
Our no wiring, plug in Suppres-
sor helps stop martns-borne tn-
terference which can be a threat
to data in micro systems. Hand-
les 1500 watts at 6 amps, re-
duces interference between 150
kHz and 100 MHz.
£19 (inc. VAT, p & p)
BEYTS
KOeKe
Windmill Rd, Sunbury,
Middx. (tel) 09327 86262
Telex: 928185
PETs ( & software) Hewlett Pac-
kard, SWTP paper, discs and
much more — all from.
Planer Building, Windmill Road,
Sunbury, Middx. (09327) 86262
And opening in September
another branch at Palmer Street,
Westminster — near Caxton
Hall.
SYSTEMS &
SOFTWARE
We supply complete small
business systems; hardware
such as S.W.T.P. and
Compelec;— software including
Mailing Lists, accounting and
information systems, stock
control, invoicing etc. and
instruction in the use of micros.
Windmill Rd. Sunbury,
Middx. (tel) 09327 86262
Telex 928185
@ Circle No. 228
125 ©
sion. The ‘professional portable’; similar to Superboard but pack-
aged and ready to use. Aimed at small business, education,
research.
Challenger C28P: similar to 4P but expandable to include two 8in.
floppies, allowing use of Ohio software. Personal computer for
larger business/commercial programs. Aimed at small business,
education and research.
Challenger C3. Min size: 32K RAM, dual 8in. floppies, triple pro-
cessor architecture (6502A, Z-80, 6800). Max size: 768K RAM, 74MB
hard disc, multiple terminals, printers. Can run virtually all 6502,
6800, 8080 and Z-80 code. Runs Basic, Cobol and Fortran under OS
CP/M. Full business software packages available, including word
proesase and database management. Multi-programming
available.
PERTEC
£435 to £1,900
£2,450 to £13,000
System 1300. Min size: 32K memory; dual minifloppy discs 71 bytes
each, formatted; serial interfaces. Max size: 64K memory; four ser-
ial ports. Basic (single and multi-user), Fortran, Cobol. The hard-
ware for Compelec Altair systems is from Pertec but the software is
Anglo-Dutch. Sole distributor Compelec (01-580 6296).
PROCESSOR TECHNOLOGY
£3,000-£5,500
Sol. 808-based S100 microcomputer packaged with cassette and
video interfaces (including graphics), keyboard with numeric pad,
and 16KB RAM. Basic, assembler, word processors. Floppy disc
systems available. Several distributors including Comart (0480
215005), which can offer nationwide maintenance contracts.
(Reviewed July, 1979.)
RAIR
Black Box. Min size: 32K memory dual minifloppy discs, 80K bytes
each; two programmable serial I/O interfaces. Max size: 64K mem-
ory; eight serial interfaces; IMB disc storage (or 1OMB hard disc);
range of peripherals. Basic, Fortran IV; Cobol. Hardware dis-
tributors are being signed and agreements made with software
houses to add software. A warranty and U.K.-wide on-site mainte-
nance is given. From manufacturer (01-836 4663) and systems
houses.
RESEARCH MACHINES LTD
380-Z. Min size: 4K memory; 380-Z processor, keyboard, Max size:
56K memory. Options: cassette, single or dual minifloppy discs,
dual 8in. double-sided discs (IMB); serial interfaces; parallel inter-
faces; 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 library. Sold principally to
higher and secondary education, and for scientific research, data
processing and data legging. Available from Sintel and the man-
ufacturer. (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.
RCA
JUST ARRIVED
QO
al
(a4
a4
ine
0
yp
<
S
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From £1,750
(excluding monitor
and cassette).
Complete floppy
disc systems with
word processing
about £5,000
From £2,300
From £830-£3,500
4KB version at
£398; 32KB for £722
Be)
S
oe)
oe)
‘i
O
<
Y,)
oe)
LL)
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wv
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
Instant Soffware
Kit £79.95.
Assembled £99.95
exc VAT
Aim-65: Kim-compatible with full keyboard and on-board printer.
IK or 4K RAM. The 4K version is described as a development sys-
tem rather than a personal computer. Assembler, editor. Basic.
Available from Pelco and Microdigital. (Reviewed July, 1979.)
SCIENCE OF CAMBRIDGE
ku: SC/MP processor, 256 bytes user memory; 512-byte PROM
with monitor program; hex keyboard and eight-digit, seven-
segment display; interface circuitry; 5V regulator on board. To this
can be added: 4K RAM (£3-60); 16 I/O chip (£7 -80); cassette inter-
face kit (£5 -95); cassette interface and replacement monitor (£7 -95);
PROM programmer (£9-95). No software provided but a 100-page
manual in¢ludes a number which will fit into 256 bytes covering
monitors, maths, electronics systems, music and miscellaneous.
Based on American National Semiconductor chips. Science will
soon have a VDU interface and large manual on user program-
FROM ONE OF
THE WORLD
LARGEST
MICRO SOFTWARE
SUPPLIERS
A COMPLETE
RANGE OF
INSTANT
SOFTWARE
PROGRAMS
(Dealer Enquiries Invited)
@ Circle No. 229
126
IK — £249,50
4K — £315
£39.95 basic
PRACTICAL COMPUTING September 1979
ming. Mail order from manufacturer (0223 312919) and by selected
dealers. (Reviewed May, 1979.)
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 parallel RS232 interfacing; keyboard; 12in. video
display; ye supplies; SD monitor program; line printer avail-
able. ep , 8080 assembler, E Basic, Editor supplied with system;
M Basic, Fortran, Cobol available for business use, industrial pro-
cess monitoring and control (with additional hardware). All CP/M
games and business packages. Sole supplier Airamco (0294 65530).
SEMEL
Semel 1. Min size: 4K with CPU, keyboard and monitor. Max size:
64K with'single floppy disc unit, printer, VDU and keyboard. Can
be coupled to any external device and controls up to 8 X250K floppy
disc units. Four configurations available. Options: Light pen
attachment; 12V DC power supply; remote terminals. Software:
Editor, Assembler, debug, full fi e-handling capabilities in Basic.
Fortran and Cobol available on 64K machine; user-defined prog-
rams written and compiled by agreement; word processing.
General-purpose unit for use as a terminal controller. Biitable for
oo business and OEMs. Available from Semel exclusively (0822)
SORD
M160. Min size: 16K RAM; 4K ROM monitor; full keyboard plus func-
tion keypad; two-channel joystick dual cassette I/F; 11K EBasic 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 busi-
ness, education, laboratory and scientific and home computing.
Main distributor is Dectrade, but for London and South contact
Midas Computer Services (0903) 814523.
M222. Min size: 64K RAM; VDU; full keyboard; numeric keypad;
graphics; real-time clock; 70K minifloppy disc drive; audio cassette
interface; two serial ports; programmable 110 to 9,600 baud; three
$100 slots; power ond interface for two external minifloppy drives;
ROM bootstrap. Max size: 70K byte a ies; black and white
or colour graphics; bar code reader; TMS- development sys-
tem. EBasic interpreter; compiler EBasic; matrix Basic; Fortran;
Cobol; assembler editor; re-locatable linker/loader; debugger.
Application software includes word and graphics processor; busi-
ness demonstration packages and games.
M223. Min size: 64K RAM; hardware as M222 plus one or two 350K
byte minifloppy drives. Max size: Four 350K minifleppies; up to four
11.4Mb hare discs; range of S100 devices. As M222 plus Cobol-80,
CAP-CPP BOS MicroCobo]. Application software includes word
and graphics Peed personal information processing system;
games; CAP-CPP range of MicroCobol software.
SYNERTEK
Sym |: 6502 chip and keypad with memory available in 4K blocks to
64K. Any Kim software. American, meant to be the foundation sys-
tem for very small business and hobbyist users. Available from
Newbear (0635 49223).
TANDY CORP.
TRS-80. Min size: Level I 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 bgt es. Level | aimed at the hobbyist and educa-
tion market and Level II at small business applications. Hundreds
of dealers. (Reviewed November, 1978.)
TRANSAM COMPONENTS
Triton: British-made kit computer. Up to 65KB. Full graphics capa-
bility, 64 characters. Power sup - cabinet. Communications
interfaces. Tiny Basic or 2K Basic, IKB monitor plus new option 4K
firmware on board. Available from manufacturer. (01-402 8137).
VECTOR GRAPHIC
48KB RAM, Z-80 micro: 63K bytes, mini-discs are standard, Options:
aphies. Moniter, MDOS, Basic; business packages from dealers.
Boreral distributors. :
PRACTICAL COMPUTING Seprember 1979
£1;950 with Basic
From £3,750
DYLE HOUSE
BUSINESS
COMPUTING
SYSTEM 2000
£5000
FEATURES
@ Dual 8 in. discs providing 2.5
megabytes of storage
@ 140 cps 132 char. printer
@ 80 char. x 24 line terminals
@ Full Z-80A power & system
within the terminal
@ Multi-cluster terminals
(superb multi-user power)
@ Dyle House business basic &
disc operating system
@ Accountancy suite free
@ Payroll suite free
@ Parts control suite free
@ Typist & clerks not required
From £726
From £3,450-£4,123
including desk
and printer
For:
Sales acknowledgments
Sales Invoices
Delivery Notes
Purchase Orders
Customer Statements
Remittance Advice
Dyle House Ltd,
Brook Crescent
From £3,775-£4,448
From £200
London E4
Tel: 01-529 2436
Level I — £499 @ Circle No. 230
Level Il — from
£578-£4,700
MICRO ADS
are ecce from private readers onty, pre-paid
and in writing, 20p per word, minimum charge
£2.
For sale two months’ old, hardly-used Pet 32KN new
QWERTY board personal computer. including two
cassetie tapes and many programs. Price asked
£790 — contact Mr. Gregory, Tel: 01-940-3930.
£286 kit with 5KB
Expand KIM.4K board (2114). Fully socketed and
tested. Plugs on to KIM. £55. S. Ramsbottom, 20
Roydene Rd, Plumstead.
For sale. Tandy TRS-80 Level 2 4K. Perfect condition.
Little used, £500. Buyer collects. Phone: Gillingham
31757 (code Medway).
£2,300
For sale — Data Dynamics Teletype KSR-33 in excel
lent condition, £350. Also keyboard in plinth, £20. Call
01-894-3761
127
Do you want to buy
a MicroComputer?
Digitus stocks a wide selection of micros
and provides expert advice, sizing and
design.
Test some robust, proven computers:
@ Apple 11
@ Cromemco
@ DG MicroNova
@ North Star Horizon
Choose from a range of peripherals:
Shugart, North Star, Sanyo, Sony, Lear
Siegler, Cifer, Centronics, Teletype.
Discuss and select a system to fit your
present and future needs.
BS BS
Call, write or visit:
Digitus Ltd
Dumbarton House
68 Oxford Street
London W1
Tel: 01-636 0105
PS Also provided:
micro skill, software, books and training.
Do you need help
to design and process
your MicroS ystems?
Through its MicroSkill Register of over
200 professionals, Digitus provides
experienced programmers, designers
and engineers to develop systems on
most micros including:
@ Z80/8080 @LSsi11
@ 6502 @ MicroNova
@ 6800
Some of the Register people have their
own machines. Others work on customer
or Digitus equipment.
Whether you require asmall program
written or a large system designed and
engineered, Digitus MicroSkill can
provide support.
BS a
Call, write or visit:
Digitus Ltd
Dumbarton House
68 Oxford Street
London W1
Tel: 01-636 0105
PS Applications to join the Register
are welcomed. Please send C.V.
and two professional references.
128
Digitus supplies application programs,
systems, and tailormade software
systems.
We specialise in business and
administration programs for Z80/8080
and MicroNova computers including:
Also supplied: systems software for
Z80/8080 including CP/M, Extended
Basic, Fortran and Interactive Cobol.
G @
Cail, write or visit:
Digitus Ltd
Dumbarton House
Does your
MicroComputer
need soffware?
@ Wordprocessing
@ Mailing
@ Sales Ledger
@ Purchase Ledger
@ Nominal Ledger
@ Stock Control
68 Oxford Street
London W1
Tel: 01-636 0105
Do you want a
MicroSolution for
your business?
Some people want to buy equipment and
software and bolt it together for
themselves.
Others want to buy a solution, a complete
system to meet their needs economically
and reliably.
Digitus provides MicroSolutions for
business, administration and
professional practices.
We analyse your requirements, specify
systems, choose suitable equipment and
software, tailor it to fit your people and
organisation, hold hands during
transition, train operators and managers,
arrange regular maintenance and
support.
In short, provide a total MicroSolution.
J B
Cail, write or visit:
Digitus Ltd
Dumbarton House
68 Oxford Street
London W1
Tel: 01-636 0105
@ Circle No. 231!
PRACTICAL COMPUTING September 1979
—— Ss | ll
A PRACTICAL
GLOSSARY
Continuing the terminological gamut from M to N
Microcomputer
Really it’s a small computer. Look at
the glossary reference to “C” and
check what we wrote there on com-
puter — a computer is more than
just a processor, It’s a functioning
whole with !/O and some storage
capability as well. So microcomputer
includes a microprocessor but it
involves enough extra equipment to
be usable — like a VDU, floppy discs,
memory and perhaps a printer.
Microinstruction
One statement of microcode.
Microprocessor
The $64,000 definition. What
exactly is a micro? Simple; it’s a cen-
tral processor — a programmable,
electronic, logic-driven, rule-
following idiot.
Microprogram
A bunch of microinstructions.
Microsecond
One-millionth of a second, usually
abbreviated as #@ (being one of
those Greek symbols mathemati-
cians use which typewriter man-
ufacturers do not include on typew-
riters). Incidentally, you might see
“up” used: it's a witty shorthand for
microprocessor.
Millisecond
One-thousandth of a
abbreviated as ms.
Minicomputer
A small computer. Nobody really has
a better definition so here’s a prag-
matic one. A minicomputer — col-
loquially a mini — is a small com-
puter which is not a micro and which
is made and sold by a company
interested in volume production and
low overheads. A mini is sold as a
system component, usually in quan-
tities larger than one and without
the nolsy support, software, cus-
tomer service people, pamphlets,
manuals and prices of the mainframe
computer vendors.
The mini makers want volume
second,
sales and high turnover; their profit |
margin per machine is small, so they |
want to sell plenty. Micro man-
ufacturers take the same line.
By contrast, the mainframe mak-
ers sell comparatively few high-cost
systems; they make their high pro-
fics per sale by all the extra services,
products and general support pro-
vided with the computer.
MITS
The personal computer business
really got under way late in (974
with an unlikely parent. MITS was
Micro Instrumentation and Tele-
metry Systems, a small company in
the southern United States which
began life in 1969 making electronic
control systems for model rockets
but moved to $199 programmable
calculators in 1971.
In 1974, MITS put together a mic-
rocomputer kit and featured it in a
U.S. magazine Popular Electronics. The
technical editor persuaded MITS to
look for a catchy name, and his
daughter offered “Altair” — she
derived it from the TV as Star Trek
was showing.
MITS sold the 8080-based Altair
kit for $398 and expected 800
orders in 1975. In fact, it sold 1,500
in two months.
MITS and Altair effectively defined
the home micro market. MITS was
sold to Pertec two years later and
the Altair name is now being sub-
merged under newer product
developments.
Mnemonic
A memory aid. So mnemonic code is
an assembly language code in which
the instruction names are easy to
remember, like MPY and for multiply
STO for store — and ADD for add,
too.
Monitor
The kid who used to look after the
milk at school. Also the most basic
kind of operating system; we treat it
as belng synonymous with executive.
MOS
Metal Oxide Semiconductor. A
number of semiconductor
technologies are used in micros but
this is the most widespread. It is a
fairly obvious way of manufacturing |
integrated circuits by using metal for
the electrical conductor and laying it
on an insulating layer of silicon
oxide.
The two popular alternatives to
MOS are bipolar semiconductors
and SOS silicon-on-sapphire.
MOS is king at the moment — cheap
and simple to manufacture and to
use. The availability of MOS made LS/
possible.
MOSFET is an IBM version of
MOS; don't worry about it, though.
Motorola abbreviation for mic-
roprocessor unit, now used widely
to mean “microprocessor”.
MSI
Medium Scale Integration. See LSI.
MTBF
Mean Time Between Failure. As an
indication of reliability, an MTBF fig-
ure — given usually in hours — can
be useful to someone who wants
maximum performance, though you
have to be careful about what
exactly has been measured and in
what circumstances.
MTTR
A much less-frequently-quoted
statistic, the Mean Time To Repair.
PRACTICAL COMPUTING September 1979
|
Multi-access
A multi-access system is one several
users can access at the same time.
The term is usually associated with
time-sharing organising the
resources of the computer so that
all users have a bite at the cherry —
and multi-programming — so that
several users can run different prog-
rams concurrently.
Multidrop
You probably won't ever hear this
| term. Generally, each peripheral —
printer, disc drive, VDU — is con-
nected to the computer by a cable.
A multidrop line is something like an
electricity line, in that several dif-
ferent units can be connected to it.
So several VDUs, say, can be con-
nected to a computer but take up
only one I/O port.
Of course, this requires some
clever internal extras, notably an
operating system which can
decipher which terminal wants to do
what. If you are sitting at a mul-
tidropped VDU and you want to
call-up the Practical Computing index
to check back references, the com-
puter will require some means of
identifying you as the recipient of
the index rather than any other
terminal on the line.
Multiplex
Another term the personal com-
puter user will rarely encounter.
Multiplexing is using one com-
munications channel to send several
messages at the same time. What
happens is that individual messages
are chopped up and the pieces inter-
leaved in a single long message. You
need a special hardware item called |
a multiplexer (or multiplexor) to do |
this. At the other end of the link you
need another to decode the
chopped stream and re-assemble it
into several messages.
lt means you can economise on
transmission line charges, because if
you have eight 30 cps terminals you
would be paying for eight 300 baud
lines; multiplexing allows you to
have all that traffic on to one 2,400
baud line.
Multipoint
Synonym for multidrop.
Multiprocessor
Obviously a bunch of linked pro-
cessors. There is much to be said for
this, particularly for throughput
reasons — each processor runs one
part of the system or one part of a
program, so there’s no waiting; and
for improved reliability, things
might be set up so that if one pro-
cessor fails another can take over
without interruptions.
A number of the cleverer mic-
rocomputers use two processors,
one to handle data into and out of
floppy disc storage while the other
runs programs. Normally a single-
processor system has to stop
executing program instructions
while it looks after a transfer of data
to or from disc.
Multiprogramming
Multi is a-most as popular a prefix as
micro, isn’t it? Multiprogramming is a
clever way of obtaining as much
work as possible from the com-
puter. It means the operating sys-
tem can run two or more programs
at the same time, switching from
one to another and giving each a few
milliseconds of operation.
Multiprogramming becomes very
complicated, though. The operating
system has to be able to decide on
an order of priorities for programs
and the actions they will want to
perform. It must also watch that
progranis do not over-write any of |
each other’s workspace. It has to
make the best possible use of mem-
ory by detecting when one program
is finishing and perhaps loading
another from disc into the memory
space thus vacated. And so on.
That means full-blown mul-
tiprogramming operating systems
tend to be too complex, too expen-
sive, and too big to run economically
on micros. Some microcomputers
allow a limited kind of mul-
tiprogramming, with an interactive
foreground program (some use of a
VDU, typically) going on at the same
time as a background batch job (like
printer output).
MUX
Abbreviation for multiplexer.
Mylar
A trade name for a polyester film
; used widely as the base for magnetic
tape. It can be coated with mag-
netisable particles.
NAK
Ephemeral mid-60s play and film.
Whatever happened to Anne Jel-
licoe? Still, that one had a “c”. This
one is “negative acknowledge”, an
ASCH (qv) character code sent bet-
| ween computer and terminal to
indicate that some duff transmission
has occurred.
Nanosecond
One billionth of a second. That's a
US. billion, which, by the way, is the
one we prefer — it’s |,000,000,000,
or 10-9
National Semiconductor
One of the giants in the US. elec-
tronics business, a $500 million
company which makes most of its
money from bulk manufacture of
semiconductor components like
(continued on page 131)
129
DATRON MICRO CENTRE
Microcomputers — Peripherals — Software — Books
(4Cromemco ITT 2020 (Apple Il) ¢< commodore
WHY PAY MORE? Complete Business System including The well-established PET with integral
“Construction never less then software and printer keyboard and screen.
excellent” (Practical Computing Feb. ‘79) from £3500 or 4K — £460
System 2 — Dual Disc — 64K — £2294 16K — £950 8K — £550
System 3 — Dual Disc — 32K — £3444 32K — £1114 a “ all
— Dual Disc — -
ne ste Hard Discs <7 Fieaies sen, laa Plus all popular games and
PP plus Discs and Printers VAT — £15
. 64K - £5748 Address book — £6
plus VDU's, Printers, Software:— Current Account — £12
Software:— Sales Ledger, Purchase Ledger, Stock Control — £12
Database, Word Processing, 16K Basic, General Ledger, Payroll and Stock Control Payroll — £25
Fortran, Cobol at £65.00 from £295. Invoicing — £20
Ae ; Basic Tutorial = £15.
Cromemco-Appointed Dealer ry ITT Appointed Dealer ry Send co +d mall et
plus Centronics, Lear Siegler and Teletype Peripherals + National Maintenance by CFM Ltd.
Books our most popular titles:— Instant Basic £7.20 Fun with Computers and Basic £5.45
Introduction to Personal and The fun way to learn Intro. to Computers and Basic
Business Computing £5.45 Basic Basic £6.50 The Best of Byte £8.45
A comprehensive and simple introduction One of the most widely sold From first 12 issues
Microprocessors-Chips to Systems £7.95 Advanced Basic £6.00 The Best of Creative Comp. £6.95
Basic text for Technically Minded What is says Vol. 1 or Vol. 2
Introduction to Microcomputers How to Program Micros £6.95 General Ledger £10.95
Vol 0 — The Beginners Book £5.95 Assembly Language for 8080, 6800 & 6502 Accounts Payable/Receivable £10.95
Vol | — Application Techniques £6.30 789 Prog. for Logic Design £6.30 Complete testing source listing
Wtcco deviitter Priiner £6.35 File layouts, formats all in Basic
ja ~° For programmers. and logic designers ITT 2020 Handbook Set. —»«£10.00
Some Common Basic Programs £6.45 PET Handbook Set £6.00
Microprocessor-Interfacing Read before you buy
Techniques 95 76 programs, finance, maths etc. Cromemco Catalogue £1.00
Introduces basic concepts Basic Computer Games £5.50 from Single card to System 3
280 Microcomputer Hand Book .95 Why not? Complete listing and Send s.ae. for full list
Essential information on Z80 sample run, plus description ComputerCapers £5.95
Iilustrating Basic .25 Computer Quiz Book £5.45 Tales of electronic thievery,
Serialized by Practical Computing Test your knowledge NS embezzlememt and fraud!
How they work for beginners
Send s.a.e. for lists or M1
visit our easily -C)
accessible showroom — Inter City or A1 (M)
for demos M62
COE ege@t SSB BBB SF SB SBS SSF SB SS SF SB SS SS SS SSS es ee aan eee eee eS Se Se,
f Cheque Enclosed] ~— or a MAIL, ‘PHONE or TELEX YOUR ORDER - 24 HOUR SERVICE ;
P Charge €......00......00. to Card No:- cam | as ee ee ee ae
| a en en
ee ee ee EE !
I Name (as on card) .......... Hardware prices plus p. & p. Add 12p insurance on books if required. |
| SAIS < Bares winx... ADD 15% VAT to all items except books. Prices correct at going to press. J
I sali . j
pone DAT RON interrorm itp.
CUE ee a anne Wicca ee oot t i
1 (ahaa ae Telephone: 0742585490
\ 243 London Road, Sheffield. S2 4NF Telex: 547151 }
eee es we ee es i os ‘ — ewe ee ee ee ee ee ee ee ee ee ee ee ee ee es es a ei a
@ Circle No. 232
130 PRACTICAL COMPUTING September 1979
a
Needle
ism.
Network
generally, a
03-5
@10-11
@10-12
@11-13
@12-13
(continued from page 129)
computer memories. It also makes
some microprocessors, notably the-; management.
SC/MP micro the Science of Cam-
bridge MK1I4 uses.
Remember the discussion of matrix
printers? Impact matrix printers
build a character by firing metal pins
against a ribbon, so that a dot is
transferred on to the paper. Using
the correct dot positions gives you a
recognisable character, even if it is
not in proper joined-up writing.
Those metal pins are also called
needles, funnily enough, and some
people speak of “needle printers” to
mean an impact dot matrix mechan-
A network is any system comprising
a series of interconnected points. So
a TV service with local stations con-
nected, by signals, to a central ser-
vice is a good example. In computing
number of terminals connected to a
computer, or it is a number of com-
puters connected together.
That second definition is
more usual one. Networks are com-
plicated technically, since there are
all kinds of traffic control and route-
ing considerations, apart from what
is actually being sent. Network con-
trol usually involves add-on black
boxes and complex special software,
| though, so that the user does not
| have to do too much of the network
A few systems are now appearing
allowing inter-connection of micro
computers — your Pet can talk to
someone else’s TRS-80 over tele-
phone lines, if you have the proper
connectors. A more usual con-
figuration would probably be a bunch
of computers all sharing each other's
local storage, or local peripherals,
and this, too, is becoming possible
now.
For instance, you could load a
program on your computer, send it
to another computer, and run it
there. Or you could pick up infor-
mation stored on another com-
puter’s discs or cassette files and use
it in your own program. You'll prob- |
ably have to know the correct |
passwords and access codes, of
course.
Say you have a cheap computer
with no printer, you might want to
dump a load of program listings
quickly to give yourself a paper copy
of your programs. So how about this
for a scenario? You send a message
to every other computer in your
friendly neighbourhood network say-
ing: “Does anyone have a fast printer
doing nothing?” Someone answers
“Yes”, plugs in the printer, and you
can run a little code dump program
which prints its output on that
friendly faraway printer. The results
arrive in the post next morning.
network is either a
the
Computer Appreciation. Venue: London. An intro-
duction to computers — what they are, what they do, how
they do it. The three-day course is organised by Control
Data Institute, 77-79 Wells Street, London, W1. Fee:
£180.
Computer appreciation for beginners. Venue: Worthing.
Very basic introduction, designed apparently for those
involved in clerical systems which may be computerised.
Fee: £190. Organised by MSS, 18A Chapel Road,
Worthing, Sussex.
Technology Employment Education International Con-
ference. Venue: Southampton University. The topic is.
changing technology and our future and constitytes ‘‘an
exploration of the consequences of fast-changing
technology upon our education and work”. Each day
there will be a separate examination of industry, edu-
cation and Government policies on employment. The list
of speakers includes Basil de Ferranti and Barrie Sher-
man (ASTMS). Each day costs £40 (non-residential) or
£75 (residential). It is sponsored by the Southern Science
and Technology Forum and registration forms can be
obtained from that organisation at Building 25, The Uni-
versity, Southampton. Tel: 559 122, ext. 2430.
Electrical & Electronics Exhibition. Venue: Exhibition
Centre, Bristol. This is the second year Exhibitions for
Industry has run this show and there will be more than
100 exhibitors displaying electronic equipment and mic-
rocomputers. Entry is free. More information from
Exhibitions for Industry Ltd, 157 Station Road East,
Oxted, Surrey. Tel: 988 4373.
User Involvement in Computing. Venue: London. An
introduction for non-data-processing staff who will be
PRACTICAL COMPUTING September 1979
NMOS
Also N-channel MOS, a type of MOS
(qv) used widely in microprocessors
and other electronics circuits.
We're not going to tell you exactly
how it differs from PMOS, an earlier
technique for making MOS circuits
but, in general, NMOS is faster,
although PMOS can usually put more
circuits on to a chip.
Noise
The otherwise
thankfully sole quality shared by the
St. Matthew Passion and the Bay
City Rollers — and transmission
lines, for noise is unwanted electrical
signals on a cable or some other
connection. Since computers work
electrically, a
effect of some kind can cause errors;
an extra amount here or there will
' totally destroy the meaning of a
single-character code,
apprehension of a single character
can affect the computer’s com-
prehension of a whole message.
Noise is unavoidable in all elec-
trical circuits. It’s a property of all
materials, including those used to
make computers, that they will gen-
erate a certain amount of electrical
activity on their own. Senerally,
though, the signals being generated
and passed around in a computer
system are powerful enough, and
the receiving ends sensitive enough,
to separate the desired signals from
the dross.
@18-19
@17-21
@24-28
Non-volatile
Some types of memory lose their
contents when you turn off the
power; that’s because they need a
permanent electric current so that
they can hold information. Because
switching-off loses contents, they
are termed volatile.
This doesn’t happen with non-
volatile memory because those
devices don't store information by
requiring a constant source of elec-
tricity.
Examples are discs and tapes,
which work by altering the magnetic
characteristics of the medium; this
alteration is done electrically but
once that has happened, the whole
thing is only encoded magnetically.
This also applies to some types of
internal memory, notably core and
ROM. The one big advantage of core
memories is that their contents
aren't lost when you switch off.
By contrast, the semiconductor
MOS memories used normally these
days in computers are volatile. MOS
has many advantages over core,
though, notably its speed; reading
and writing information is much fas-
ter with MOS; its heat output —
MOS runs much cooler, so reliability
is better; and its cost — MOS is
already much cheaper and it’s
becoming even more so.
ROM (read-only memory) is the
other significant form of non-volatile
storage. These are semiconductor
chips with data sealed-in. |
indefinable and
spurious electrical
and mis-
September
involved with computer systems. The fee is £175 and the
course is organised by Learmonth Burchett Management
Systems.
Microprocessors. Venue: London. Unequivocal if some-
what general title for this two-day introduction. These
seminars promise a non-technical introduction plus a
look at applications in ‘‘business, industry, government
and education”. Speakers are promised from man-
ufacturers, consultancies and users. The fee is £78 and
the seminar is organised by Informex, 61 Harland
Avenue, Sidcup, Kent.
Microcomputers for the Uninitiated. Venue: London.
This five-day course is aimed at industry, management
and people ‘‘with a wide range of backgrounds’. It is
designed to give an insight into what a microcomputer is,
covering the basic principles of languages and prog-
ramming, binary counting, memory, CPU storage,
addressing systems and 8080 instruction sets. There is a
good deal of practical work in the course and each dele-
gate has his own I/O device and microprocessor. The fee
is £125, to include refreshments, lunches and course
material. Further information from the Course Co-
ordinator, Babcock Controls Training College, 165
Great Dover Street, London, SE1. Tel: 01-407 6373.
Microprocessor-based Equipment Design and Develop-
ment. Venue: Sevenoaks, Kent. This five-day residential
course is intended for project managers and engineers
concerned with incorporating microprocessors into
measurement and control equipment. It covers design
methods and good practice, development procedures,
development aids and how and where to obtain further
help. The fee is £480 plus VAT, which includes accom-
modation, course documentation and full board. Further
information from Sira Institute Ltd, South Hill, Chis-
lehurst, Kent. Tel: 01-467 2636.
131
The microcomputer for those who
need more than the minimum. The
right processor for business.
scientific and educational use.
Proven applications include Games
e Educational e Word Processing e
Invoicinge StockControl
e Sales Ledger «
Purchase Ledger e
Mailing e Scientific.
_ The Horizon computer
includes:-
Languages
Powerful Basic including sequential
and random access disc files e
formatted output e strings e line
editor e machine languaageCALLe
many other facilities. Optional
additional software
(under CP/M
operating system)
includes BASIC
compiler. FORTRAN and COBOL.
Horizon Z80A computer with 2 double~density
disc drives and 24K RAM £1,823 (exclusive of
Specification
Zilog Z80A MPU e S-100 bus (12 slots) ¢ Solid
well-built case e Up to four Shugart mini-floppy
disc drives. I830KB each e Serial port for CRT or
Teletype e Real-time clock on motherboarde
Optional additional
= \ serial port and
parallel port e
Powerful
operating
system and monitor
¢ Access to wide
range of S-100
special application
boards.
VAT and carriage).
Equinox Computer
Systems Ltd.
“Kleeman House”
16 Anning Street,
New Inn Yard,
London EC2A 3HB.
Tel:01-739 2387/9,
01-729 4460.
For North Star Horizon systems and software
contact the people with experience:
LONDON
Equinox Computer Systems Ltd
16 Anning Street, New Inn Yard,
London EC2A 3HB
(Tel: 01-739 2387/9-01-729 4460)
HUNTS
Paxton Computers, 26 High Street,
Great Paxton, Huntingdon,
Cambs. PE19 4RAF. (Tel: 0480-
213785).
HANTS
Claisse-Allen Computing, 5 Upper
High Street, Winchester.
(Tel; 0962-69368).
BERKSHIRE
DISKEL Ltd., 120 High Street,
Slough, Berks. (Tel: 75-22855)
LANCS & NORTH WALES
Cortex Computer Centre, 25/35
Edge Lane, Liverpool
(Tel: 051-263 5783)
KENT
Microtek Computer Services. 50 Chislehurst Road.
Orpington Kent. (Tel: 66-26803)
Tor Business Systems, 83 Timberbank, Vigo Village.
Meopham, Kent. (Tel: 0732- 822956)
ESSEX
SROFCOMP Ltd.,
£18 1AN (Tel. 01-989 8177).
DORSET ANO SOMERSET
Blue Chip Micro Systems Ltd.,
(Formerly Micro Systems
Specialists), Market Place,
Sturminster Newton,
Dorset DT10 1BB.
(Tel: 0258-72946).
YORKS
Weyfringe Ltd, Marske, Redcar,
Cleveland TS11 6HOQ
Tel: (06493-70121).
SCOTLAND
Scotia Software Services Ltd.,
29, Chester Street, Edinburgh
EHS 7EN. (Tel: 031-441 6031).
CAMBS
Wisbech Computer Services Ltd.,
10 Market Street, Wisbech,
Cambs.
(Tel: 0945-64146).
OEVON
J.A.D. Integrated Services
(Plymouth) Ltd.,
21 Market Avenue, City Centre,
Plymouth, Devon. (Tel: 0752-
62616).
MIODX
Jacobs Computer Systems Ltd.,
36 Bengeworth Road, Harrow
Middx. HA1 3SE.
(Tel: 01-908 1134).
Micro Facilities, 127 High Street
Hampton Hill, Middx. TW12 1NJ.
(Tel: 01-979 4546).
SOUTH WALES
Micro Media Systems,
12 Clarence Place,
Gwent.
(Tel: 0633-50528).
LINCS
Loveden Computer Services,
167 Bartowby High Road,
Grantham, Lincs. (Tel:
72000)
Newport,
0476-
FOQUINOX
COMPUTER SYSTEMS LTD.
107 George Lane, South Woodford.
“Kleeman House” 16 Anning Street.
New Inn Yard, London EC2A 3HB
Tel:01-739 23879. 01-729 4460.
@ Circle No. 233
PRACTICAL COMPUTING September 1979
Ge CAREER Naa. AREE Kian: ARLE
SERVICING BY ,
PROFESSIONALS
THE COMPANY
BASIC PROGRAMMERS
WITH BUSINESS EXPERIENCE
Kode Services Limited, part of the British-owned Kode
International Group of Companies, is rapidly becoming a
major U.K. service operation specialising on a whole range
of equipment from basic terminals to microprocessor-based
systems.
Over 100 Field Service Engineers nationwide, coupled with
full depot and workshop facilities, are available to support
MML seeks programmers and business applica-
tions experts to join a team developing comm-
ercial packages in CBASIC on CP/M driven
micro-computers.
the following oa TT bes
Model 33, 40, 43 Lear Siegler ADM1A, 2A, 3A, ADM42
and 31, Microstar V, Anadex D8000 Printer. We have the
capability to service new products and are always
evaluating new DP equipment.
Fully: -comprehensive maintenance contracts or a full depot
repair setvice can be offered.
THE CAREER
Opportunities are available for experienced
professionals and Ye amateurs who have a full
understanding of TTL logic and digital techniques, and
wish to move into a service-orientated career applying
their knowledge to-the servicing of sophisticated
electronic equipment.
For further details on maintenance or job prospects,
please call or write to Mr C. Marklew on 0249 813771.
Kode Services Ltd.,
Station Road,
Caine,
Wiltshire.
If you can develop high quality systems in
Basic and if you have rudementary know-
ledge of accounts packages, we can offer you
a rewarding opportunity with profit sharing.
CPA BABI SS SS
Please send your details to:
D. POWYS-LYBBE
MML
11 SUN STREET
FINSBURY SQUARE
LONDON, EC2
01-247 0691
AE IS LO LO ELE EL
OOOO OOOO OOO OOOO DDD ODORS?
Advertisement Index
Acorn Computers 86 | Datron Interform 130| LTT Electronics 18 | Robox (Office Equipment
Adda 14| Digitus 128 Systems) 54
Airamco ff Microbits 31 | Rostronics Computer
A J Harding 18} Electronic Brokers 38| Microcentre 2 Centre 74
Almarc Data Systems 28 | Equinox Computer Microcomputer Store 24 a ewe is
Anadex 74| Systems 40, 80, 132 | mj ciea| fOnneaeeae| Eo ence Ol Wagioricge
crodigit » 13, 16, SEED 44
Analog Electronics 104 Micromedia (Systems) 12 Si Microsh 66
Factor One Microsolve Computer ao mee,
es dee Small S E ng 12
Byte Shop, The 21 Computers SGER Gargices 38 - eae ge es
Four on Four 34) Midwich Computer Co 23 tae ies 4 et
Cambridge Computer pl . neh pau ig
echanical Engineering |:
Cc i El ee aon = Mine of Information 36 = i .
ae tontes Muller (Anglo-American Tandy 82
Chiltern Microcomputers |4| Grama (Winter) it 35
i, : Computers) T & V Johnson.
Christian Audio 110 Mi Ete 6.7
Chromasonic Electronics 24 Happy Memories 20 E esas pias te on
Ricadel Products 34 | Hazeltine 32 | Newbear Computer aaa Tec nologics 4
Comart 5,76 | HB Computers 22 rig 9 Dy Orr ab
Commodore Systems Henry’s Radio 30| NI odels Jil
Division 37 | HL Audio 80, 110 2
Comp Computer ae FRc ee U Microcomputers 16
Components 134, 135 Integrated Circuits ersonal Computers ; \
Computastore 15] Unlimited 39| Petalect Electronic ae ae P|
Computerbits 22 | Inter Systems 100 Services 25 Vee Eibcereis 30
Computer Field Isherwoods 99| Petsoft 58
Maintenance 92 PIPS he Whymark Instruments 74
Computer Workshop 136] Keen Computers 52| Powerhouse 80
Computrade 4\ Preston Computer Store 24 xitan Systems 109
Crofton Electronics 110| L & J Computers 18| Protechnic 36
Crystal Electronics 32 | Linburg Electronics 20 Zilog (U.K.) 42
Lion Computer Systems 94) Rair Timesharing 51, 96, 97 | —
Data Efficiency 4} Lotus Sound 70| Research Machines 33 | Careers 133
Data Precision 17 | LP Enterprises 8,9! Research Resources 4| Shop Window 114-127
PRACTICAL COMPUTING: September 1979 133
JUST COMPARE OUR CASH AND CARRY PRICES!*
PET COSTS LESS a | cet
ATCOMP andits =~ [Ae
) apedigree i q
in the U.K. Affordable
for the first time user and
the professional check out
the PET, the world’s most
popular personal computer.
8K — £499 16K — £590
32K with GREEN SCREEN — £690° Cassette recorder now in stock £55
ADD A PRINTER TO YOUR PET
RS232C 1/0 CARD
Attach to any RS232 printer, modem, accoustic coupler to your PET. Easy to
assemble. £89 In kit form. Add £20 for fully assembled and tested.
| PET TO $100 FOR MEMORY
PEXPANSION ox 3.Soke
supported $100 ‘bus. Comes complete.
Connectors and documentation included. Ready assembled and tested.
Our price £89.
SOUND BOXES FOR PET
| Fully assembled with documentation how to add sound effects to your
le Programs £14.90
| BEST GAME EVER! «20-0 ion
a This game will have you and yous
__tamily, in tears for hours! For full effect buy sound box too! Best seller in U.S.Aj
| NASCOM IMMEDIATE
| EXPANSION $100 from COMP
| =strongly recommended
The only available $100 motherboard kit: (fully buffered) that
plugs directly into your Nascom. Designed for the insertion
of $100 boards (e.g. Static RAM, EPROM and discs etc.).
$100 Motherboard/Buffer £47.50 ) Buy both and
(Complete kit + documentation) get 2K Tiny
Suitable 8K Static RAM Memory-£4+25 £110 Basic On
(fully assembled tested and guaranteed) cassette FREE.
‘MODULATORS UHF Channel 36
Standard 6 meg band width £2.25
High Quality 8 meg band width £4.90 EX:‘STOCK
UNIVERSAL POWER SUPPLY
Suitable for Nascom |, Nascom Ii, Superboard and all computers requiring
these specifications.
+5V @3amps +12V @ 1amp —5V @ 500 mills —12v @ 500 mills
Easy to construct — complete with transformer Our price £24.90
Primary 220V with 2 individual
TRANSFORMER *"22.22.0""22%:
8V —0 —8V @1% amps 16V —0 —16V @ % amp
HITACHI PRO MONITORS
Superb definition 9” — £132 12” — £210
134
THE TRS-80 (SPECIAL SCOOP)
Low Priced, Ready toGo! =»
PLUGS INTO YOUR OWN TV
Use: your-own cassette
Level-Il with 4K RAM
Improved graphics, print formatting, and a faster cassette transfer rate are
features of Levell-I] Basic. £350 + VAT
Level-Il with 16K RAM
A combination of 16K RAM and the powerful Level-1! BASIC produces a system
capable of handling most demands. £399 + VAT
64 chars x 16 lines — double length characters available at a single keystroke
giving 32 chars x 16 lines. Super graphics a 2x 3 cell arrangement. Masses of
software available.
Worlds most popular machine. Fully converted to English Television standard
Rock steady picture — exclusive to COMP.
UK POWER SUPPLY SUPPLIED
KEY BOARD ONLY — Complete with UHF Modulator
RS232C 1/0 CARD for TRS80
Connect your TAS80 to any RS232 printer. Assembled and tested £55
SOUND BOXES FOR TRS80
Fully assembled with’ documentation how to add sound effects to your
programs. £14.90
TRS80' Cure the video shakes. Upgrade your video to Englishy
S Standard. Simple modification. Only £7.50 including easy
to follow instructions. Only 15 minutes of your time needed. You owe it to your
eyesight. Fitted as standard to all our machines.
NEW! AT LAST 8K BASIC ¢
FOR NASCOM COMPLETE ON S100
BESTGAME EVER! “stro
This game will have you and your family in tears for hours!
For full effect buy sound box too! Best seller in U.S.A.
TRS80 TO S100 BUS "3."
TV UHF MODULATOR FOR TRS80
Encased ready to use — £15
ELECTRIC PENCIL °
Please add VAT to all prices — Delivery at cost, will be advised at :
time of purchase. Please make cheques and postal orders payable \@
to COMP, or phone your order quoting BARCLAYCARD, ACCESS, =
DINERS CLUB or AMERICAN EXPRESS number. =,
===
OPEN — 10am to 7pm — Monday to Saturday A, EN ce
CREDIT FACILITIES ARRANGED :
axsried
Farmar r=fFao FR PRiirF FOaPFaPamiai fr» Fr PriA"™A i LAr if= Ahan.
Text Wordprocessing package
on cassette £59
AARCLAYEARD
PRACTICAL COMPUTING ‘September 1979
he! CO eS eee | ee LS ee, ee a Ae ee Be ee Be Le hd
( OMPUKIT UK101
LOW COST:
EUROPES FASTEST SELLING ONE BOARD COMPUTER —
JUST CHECK THE SPEC’S.
The Compukit UK101 has
everything a one board ‘superboard’ should have.
Uses ultra-powerful 6502 microprocessor
50Hz Frame refresh for steady clear picture
(U.S.A. products with 6O0Hz frame refresh always
results in jittery displays)
48 chars by 16 lines — 1K memory mapped video
P *
SU FERBOARD system providing high speed access to screen display
enabling animated games and graphs
Extensive 256 character set which includes full
desire anywhere on the screen.
* 8K full Microsoft Basic in ROM compatible with
PET. APPLE SORCERER hence taking the headache
out of programming by using simpie English
Statements. Much faster than currently available
personal computers
* Professional 52 Key keyboard in 3colours — soft
ware polled meaning that all debouncing and key
*
upper and lower case alphanumerics. Greek symbols
for mathematical constants and numerous graphic
characters enabling you to form almost any shape you
q ‘ a << ie
* Video output and UHF Highgrade modulator (8Mz
Bandwidth) which connects direct to the aerial socket
of your T.V. Channel 36 UHF
* Fully stabilised 5V power supply including trans-
former on board.
* Standard KANSAS city tape interface providing
high reliability program storage use on any
standard domestic tape or cassette recorder
* 4K user RAM expandable to 8K on board £49
extra
* 40 line expansion interface socket on board for
attachment of extender card containing 24K RAM and
disk controtler. (Ohio Scientific compatible)
* 6502 machine code accessible through powerful
2K machine code monitor on board.
* High quality thru plated P.C.B. with ali I.C.'s
mounted on sockets
A tape of 10 programs on cassette —
educational games, etc. will be supplied free of
charge with each kit.
Simple Soldering due to clear and consise
instructions compiled by Dr. A.A. Berk, BSc.PhD
decoding done in software
FULL CONSTRUC
Delivery date
IN P.£. AUG 1979 EDITION
at the 1979 MicroComputer Show
Customer orders in strict rotation only.
NO EXTRAS NEEDED JUST HIT f
‘RETURN’ AND GO.
Build, understand, and program your own
computer for only a small outlay.
ONLY €219 + VAT
including RF Modulator & Power supply
Absolutely no extras.
TION DETAILS
June 1979
COMMANDS
STATEMENTS = aaa oN Due to the new prices of TTL this price will be
CLEAR DATA DEF DIM END FOR increased shortly. So order now to beat the
GOTO GOSUB IF GOTO _IF.THEN INPUT LET pricelingrescestanctnelusth:
NEXT ON.GOTO ON..GOSUB POKE PRINT READ
REM RESTORE RETURN STOP ree CHARACTERS
4 @ rases line being typed. then provides carriage
EXPRESSIONS return. line feed
OPERATORS 192 +32 @_ Erases last character typed
nu The +.°./.4 NOT.AND.OR, >< <7, =<= RANGE 10~* to 10 CR Carriage Return — must be at the end of each
xan Compukit VARIABLE Hine
Patyas tess t eenenny 1°08t Bei AgBIC. Sand two letter variables Separates statements on a line.
Character Set
COL2SAS EROS a CID?t i
FUNCTIONS
ABS(X) ATN(X) COS(X) EXP(X)
TASK O TEA Mi LOG(X) PEEK(!) POS(I) RND(X)
ARE EIT SPC(I) SQR(X) TAB(I) TAN(X)
e STRING FUNCTIONS
ASC(X$) CHR$S(!) FRE(X$) LEFTS(XS.
RIGHTS(XS.1) STRS(X)
THE EXIDY SORCERER. S4y,
SORCERER YA > 4
COMPUTER SYSTEM
The Sorcerer Computer is a completely
assembled and-tesied computer system
Standard configuration includes 63-key
typewriter-style keyboard and 16-key
numeric pad, Z80 processor, duai cassette
1/0 with remote computer control at 300
and 1200 baud data rates, RS232 serial 1/O
tor communications, parallel port for
direct Centronics printer attachment, 4K
ROM operating system, 8K ROM
Microsoft BASIC in Rom Pac™M cartridge,
composite video of 64 char/line 30 line/
screen, 128 upper/lower case ASCII set
and 128 user-defined graphic symbols,
operation manual, BASIC programming
manual and cassette/video cables, connect-
ion for $-100 bus expansion
a
*32K RAM on board
*RS232 interface *8K BASIC ROM
“CUTS interface ‘4K MONITOR
“KANSAS CITY interface °S100 BUS
"User defined graphic symbols *Z80 cpu
16K 2860 £725 " 32K £952 £790" Credit facilities available. =e WAT
IBM GOLF BALL SELECTIVE
PRINTER Refurbished to new specifications.
RS232C serial interface. Comes complete
on stand — ‘floor mounting. Small and compact. Interfaces to Exidy Sorcerer,
TRS80 Apple and ITT 2020, Pet, Compukit and Nascom.
Complete your word processing system with a
top quality printer for only £990.50.
__14 STATION ROAD, NEW
COMPUTER
COMPONENTS
VISIT OUR NEW SHOP AT 1 WALLCOT BUILDINGS, LONDON ROAD, BATH, AVON.
OPEN — 10am to 7pm —
The above can all be subscripted when used in an
array. String variables use above names plus $.e.g. A$
CLOSE TO NEW BARNET BR STATION — MOORGATE LINE
CONTROLIC Execution or printing of a list is
interrupted at the end of a line
‘BREAK IN LINE XXXX™ is printed. indicating tine
FRE(X) — INT(X) number of next statement to be executed or printed
SGN(X) — SIN(X) CONTROL/O No outputs occur until return made to
USR\(I) command mode. If an Input statement is encountered.
either another CONTROL/O is typed. or an error
\ EN(X MIDS(X$.I.J) QCCUFS
) ace ‘ \ ? Equivalent to PRINT
THE ATARI video computer system
Atari's Video Computer System now offers
more than 1300 different game variations
and options in twenty great Game
Program™ cartridges!
Have fun while you sharpen
your mental and physical
coordination. You can play
m rousing, challenging, sophisticated
video games, the games that made
Atari famous.
You’l! have thrill after thrill, whether
* ™ you’ in the thick of a dogfight,
rs screeching around a racetrack, or
“—) dodging asteroids in an alien
galaxy. With crisp bright colot (on
color TV) and incredible, true-to-life
sound effects. With special circuits
to protect your TV.
Cartridges now available
Basic Maths, Airsea Battle, Black
Jack, Breakout, Surround, Spacewar,
Video Olympics, Outlaw, Basketball,
Years and
years of fun and
satisfaction are
assured Allah
SAVE £30 ee £138.85 £1590
All prices exclude VAT. Our VAT rate is 896, We will pay any extra.
Please quote this number PC 100 when ordering
BARNET, HERTFORDSHIRE TEL: 01-441 2922 (Sales)
01-449 6596
TELEX: 298755
(Part of the Compshop Ltd. Group).
Monday to Saturday
Ali Products Ex-Stock
Please check availability
@ Circle No. 309
\36
The World’s Most Powerful 8-bit Microcomputer
Two types of central processor are available for use in
your system. The standard /09 has a maximum
random access memory (RAM) capacity of fifty
six thousand (56K) bytes. It can have as many as
eight input/output (I/O) devices such as terminals,
printers, etc, attached. This capacity is adequate for
business systems requiring up to four terminals and
two printers. If the application involves moving large
amounts of data, or scientific and engineering
calculations, ourlarger CPU should be used.
The S/09 CPU has a maximum RAM memory capa-
city of 384K bytes. It is normally supplied with 128K
bytes of memory which can be expanded to 256K, or
384K by adding additional memory arrays. This CPU
willsupport up to 16 1/O devices.
Both CPU's are designed around the Motorola
MC6809 microprocessor. This is the most powerful
eight-bit microprocessor available.
Featuring the world’s most powerful
MPU—the Motorola MC-6809
The MC6809 has more addressing modes than any
other 8-bit processor. !t has powerful 16-bit
instructions, and a highly efficient internal architec-
ture with 16-bit data paths. It is easily the most
powerful, most software efficient, and the fastest
8-bit general purpose microprocessor ever.
The greatest impact of the Motorola MC6809
undoubtedly will be software related. Ten powerful
addressing modes with 24 indexing submodes,
16-bit instructions and the consistent instruction set
stimulate the use of modern programming tech-
niques, such as structured programming, position
independent code, re-entrancy, recursion and multi-
tasking.
C/09 CPU 56K £1,050 + VAT
CS/09 128K £2,100 + VAT
/09 board (will directly replace existing SWTPC
processor board) £195 + VAT
CT-82 Terminal
XN
* Software function controls
* 56-key “Cherry” keyboard
* 12 key numeric or cursor
control pad
* 128 control functions
* Graphics capability
* User programmable
character sets
Software selectable Baud
rates (50-38, 400)
£550 + VAT
Write or telephone for latest brochure including 16MB disc and new printer range.
Sule
Southwest Technical Products Co.
Computer Workshop
38 DOVER STREET - LONDON - WIX 3R8B - Telephone: 01-491 7507 : Telex: 268913
@ Circle No. 310
Open Library