HOWTO Boot Apple PowerPCs From A USB Drive In Open Firmware

HOWTO Boot Apple PowerPCs From A USB Drive In Open Firmware

The BIOS for Apple PowerPCs is Open Firmware. It is the only way to boot the machine from anything but the hard disk or the CDROM.

Note: Some older G3 models can access Open Firmware via an external terminal. If you have one of these, you need an external terminal or another PC that can emulate one.

Note: You may want to print this out before you start.

Accessing Open Firmware

To access Open Firmware (OF):

Plug in the USB drive before you reboot. Reboot the machine and between the chime and the first screen, hold down the opt + cmd + o + f keys. You should see the OF prompt.

  0 >

Determining The USB Drive

List all the devices on the machine. Write down the ones with usb.

Note: This is from my machine. YMMV

  0 > dev / ls
  ff972e78:    /usb@18
  ff9a4fa8:      /mouse@1
  ff97ab00:    /usb@19
  ff9a4f80:      /disk@1

In this case, the USB drive is /usb@19. Write it down.

Using The Device Alias

OF has aliases for the device to make using them easier. Find the alias of the USB drive.

  0 > devalias
  usb1                  /pci@f2000000/usb@19

In this case, it's usb1. Write it down.

Booting The USB Drive

The boot commands boots the machine.

  0 > boot usb1/disk@1:2,\yaboot

After a bit, you should see the boot.msg you stored in the USB. Choose the boot image you want to start. To get a listing of all the images, press TAB.

Note: Booting from a USB drive may be significantly slower.

To Boot The Hard Disk

To boot from the hard disk in OF, use:

  0 > boot hd:,\\:tbxi

Original Author

Shawn H Corey <SHCOREY at>

Contributing Authors

(Insert your name here if you modified this documentation. Do not remove this comment.)


Thanks to Skeeve42 at Ubuntu forums for his pointers.

Thanks to for their insights on Open Firmware works.

Copyright & Licences

Copyright 2010 by Shawn H Corey. All rights reserved.

Document Licence

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with the Invariant Sections being Original Author, Copyright & Licences, and Document Licence.