USB Boot with PowerPC Mac

When you have an old PowerPC Mac but no OS DVD, you have a problem. You cannot boot from USB as these old PowerPCs only support booting from internal disks, cds or via firewire.

There is however a way to convince your old Apple’s OpenFirmware, that your usb drive is actually a cd-drive and here is how to do it.

To enter OpenFirmware hold down Command-Option-O-F.

Now in order to make this work, you need to find out which usb device your thumb drive is mapping to.

0 > devalias
[...]
usb0    /pci@f2000000/@15
usb1    /pci@f2000000/@15,1
usb2    /pci@f2000000/@15,2
hd      /pci@f4000000/ata-6@d/disk@0
[...]

Now we know how to address our usb drive. Let’s map it to the alias “cd”. And next load the bootloader.

0 > devalias cd /pci@f2000000/usb@15/disk@1
0 > boot cd:,\System\Library\CoreServices\BootX

In order to test if your alias is working, you can run this command and let open firmware show you a directory listing:

0 > dir cd:,\ \