This section will walk you through pre-installation hardware setup, if any, that you will need to do prior to installing Debian. Generally, this involves checking and possibly changing BIOS/system firmware settings for your system. The “BIOS” or “system firmware” is the core software used by the hardware; it is most critically invoked during the bootstrap process (after power-up).
There is normally no need to set up the BIOS (called OpenFirmware) on PowerPC systems. PReP and CHRP are equipped with OpenFirmware, but unfortunately, the means you use to invoke it vary from manufacturer to manufacturer. You'll have to consult the hardware documentation which came with your machine.
On PowerPC Macintoshes, you invoke OpenFirmware with Command (cloverleaf/Apple)+Option+o+f while booting. Generally it will check for these keystrokes after the chime, but the exact timing varies from model to model. See http://www.netbsd.org/Ports/macppc/faq.html for more hints.
The OpenFirmware prompt looks like this:
ok 0 >
Note that on older model PowerPC Macs, the default and sometimes hardwired I/O for OpenFirmware user interaction is through the serial (modem) port. If you invoke OpenFirmware on one of these machines, you will just see a black screen. In that case, a terminal program running on another computer, connected to the modem port, is needed to interact with OpenFirmware.
The OpenFirmware on OldWorld Beige G3 machines, OF versions 2.0f1 and 2.4, is broken. These machines will most likely not be able to boot from the hard drive unless the firmware is patched. A firmware patch is included in the System Disk 2.3.1 utility, available from Apple at ftp://ftp.apple.com/developer/macosxserver/utilities/SystemDisk2.3.1.smi.bin. After unpacking the utility in MacOS, and launching it, select the button to have the firmware patches installed to nvram.
Display-visibility on OldWorld Powermacs. Some OldWorld Powermacs, most notably those with the “control” display driver, may not reliably produce a colormap under Linux when the display is configured for more than 256 colors. If you are experiencing such issues with your display after rebooting (you can sometimes see data on the monitor, but on other occasions cannot see anything) or, if the screen turns black after booting the installer instead of showing you the user interface, try changing your display settings under MacOS to use 256 colors instead of “thousands” or “millions”.