17 January 2020
The Power Mac G4 MDD (Mirrored Drive Doors) FW800 (FireWire 800) was the first Power Mac to drop support for Mac OS 9 and native booting. Architecturally it is almost identical to the other MDD models with the exception of having a FireWire 800 port.
Downgrading adds the benefit of being able to select OS9 form the startup disk control panel in OSX, and in the multi-boot screen on boot (holding the Option key on boot). It also means you don't need any special modifications to install/run Mac OS 9. Mac OS 9.2.2 can be booted from a CD and installed just as it would on any other machine.
The folks at Mac OS 9 lives have been able to create a Mac OS Rom that can run OS 9 on the machine without a firmware downgrade, however, OSX still recognises that it's not officially supported which can make dual booting can be difficult.
Please note that downgrading is irreversible and there is no version 4.8 Firmware update file available (the default firmware version for this machine). This was never released by apple and there were no official firmware upgrades.
Disclaimer: Performing the following steps may cause irreparable damage to your machine. Proceed at your own caution!
devalias) usb0, and usb1. You can go through each one and type the command
lsto list all child devices within each USB port.
dev usb0 ls
This shows all of the devices connected to the usb0 port.
goto run the Firmware installer/Fourth code