LeopardAssist is now open sourced under the GPL. Source code and binaries can be obtained by clicking the above banner.
LeopardAssist originated from LowEndMac in Dylan McDermond's December 6th 2007 post "Faking Out the Leopard Installer with Open Firmware". The simple techniques he used in that article became the basis for the structure we were about to use.
LeopardAssist does just what was posted in his article. Using a temporary Open Firmware "trick", it changes the reported CPU speed to 867mhz and starts the installer from CD.
In technical terms, the application writes a file, "boot.txt" to the root directory of the hard disk, and configures the NVRAM (PRAM) to boot from it. On restart, Open Firmware reads the file which contains instructions to change the reported CPU speed, switches to CD or DVD and boots from it, where the Leopard installer takes over.
This simple trick means you don't have to modify your DVD to install Leopard. Finally, when installation is done or when installation is ready to reboot, you simply flash the PRAM back to restore the original CPU speed and restore booting from the hard disk.
That's all there is to it!
What systems does LeopardAssist support?
Testing is being constantly conducted on various systems, so far we have positive reports from users of Sawtooth, Digital Audio, Gigabit Ethernet and Cube Macs. Other systems including the QuickSilver and Mirrored Drive Doors G4s, iMacs and eMacs are in active testing from the community.
Each system is different and as such, it's difficult to determine which systems will successfully run. A constantly updated compatibility list can be found here.
Are there any risks?
None. However we do suggest you have a decent knowledge of Macs and how to install Mac OS X. The most common problem we encountered during beta stages was the odd system would continue restarting from CD. We found the problem was easily fixed by resetting the PRAM. This may occur after Leopard has finished installing, so when the system restarts, just flash the PRAM and all will be well.
No other risks were found, and all effects of LeopardAssist are 100% reversible by simply, as always, flashing the PRAM to return to a previous state by holding down Command (Apple) + Option + P + R and restarting the machine until you hear the second chime.
Testing is being constantly conducted on various systems, so far we have positive reports from users of Sawtooth, Digital Audio, Gigabit Ethernet and Cube Macs. Other systems including the QuickSilver and Mirrored Drive Doors G4s, iMacs and eMacs are in active testing from the community.
Each system is different and as such, it's difficult to determine which systems will successfully run. A constantly updated compatibility list can be found here.
Are there any risks?
None. However we do suggest you have a decent knowledge of Macs and how to install Mac OS X. The most common problem we encountered during beta stages was the odd system would continue restarting from CD. We found the problem was easily fixed by resetting the PRAM. This may occur after Leopard has finished installing, so when the system restarts, just flash the PRAM and all will be well.
No other risks were found, and all effects of LeopardAssist are 100% reversible by simply, as always, flashing the PRAM to return to a previous state by holding down Command (Apple) + Option + P + R and restarting the machine until you hear the second chime.
We offer LeopardAssist to the public, free of charge in the hopes it will help get Leopard on to those older machines. Consider it a service to the community, and we hope you find it useful.