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How to boot PPC PowerMacs (G3, G4, G5) from a USB stick or drive?

Category: Boot , Open Firmware , USB
Composed by: that-ben
On: 2018-09-05 18:36:54
Updated by: lavanci
On: 2024-03-31 18:08:43

To boot any* PowerPC Mac (e.g. an iMac G3, an iBook G4, a PowerMac G5, etc...) from an USB stick or drive, FIRST know that if your model is 300mhz or faster, then first refer to the boot from CD guide and if it does not work, then follow these instructions:

* The Lombard PowerBook G3 cannot boot from USB

1. Connect your USB stick/drive in a root USB port on your PowerPC Mac.

2. Power it on (or restart it if it's already running) and immediately...

3. ...hold down those 4 keys together: [ CMD + OPT/ALT + O + F ] until you see the white Open Firmware screen similar to this:


4. Then at the Open Firmware command prompt, type this and press ENTER:

(Please make sure that there are 2 backslashes before :tbxi)

Note: You may have to change usb0 for usb1 depending on which port you plugged your USB stick in.  If it still doesn't work, you can try this command:

Note 2: If you want to boot a non-Macintosh partition, say for instance a PPC Linux distribution, then change tbxi for yaboot

Note 3: If you get a CAN'T OPEN error, it means that you forgot to plug in your USB stick BEFORE powering on the computer, so turn the Mac off and start over from step #1.


Finally, sometimes it just doesn't work, no matter what.  It could be that the disk image you cloned was not correctly dumped to begin with and it is lacking a tiny partition or a boot sector that prevents your Mac from booting it today, or it could be that your USB ports are not behaving correctly.  Know that if this process fails, there is another method which will require you to temporarily borrow an old hard drive to launch the Mac OS X installer.


Learn a lot more about Open Firmware commands over at

One useful command that I'll leave here (for future reference for myself, because I forget stuff!) is if auto-boot cannot automatically find the System Folder that you want to boot (or if it auto-boots to the wrong one and there's an issue which makes your Mac crash) AND if you actually know where it is, then you can try this command (adapt the drive part, e.g. hd for hard disk, ud for USB) :

  • Booting Mac OS 9.2.2 from a given subfolder on the hard disk:
  • Booting Mac OS X from a given subfolder on an USB drive: