I’ve heard a lot of incorrect info in chat rooms and on message boards regarding this topic recently, so I figured this would be a great starting point for today’s post.
People seem to ask “Can you boot from a USB device on a PowerPC Macintosh?” and that’s where the fun starts! Loads of people pile on to comment about how that isn’t possible, and it’s an Intel-only thing and all that is just plain wrong.
There are, as with most old Mac stuff, caveats. These are simple however. The computer you’re doing this with must have built-in USB — no freaking way will you ever get this working with a PCI card. Sorry that’s just not going to happen so forget it. Next, your flash drive or external USB hard drive MUST, and I cannot stress enough, absolutely must be formatted with the Apple Partition Map scheme, and use HFS or HFS+ filesystem. I recommend HFS+ for just about everything since it’s supported on OS 9 and up and required by most releases of OS X.
Now that we have that stuff out of the way, let’s get into the details of how this gets done. Booting a USB device on a Macintosh can be annoying, irritating, and about as productive as a dung beetle rolling a camel turd uphill in a sandstorm, but anywho, you’re here because you like this type of project anyway.
A brief note – operating system software such as Panther or Tiger came in both CD and DVD media varieties. Using CD based versions won’t really be that useful since you want the entire installer in a single image to start with.
If you block-copy the 10.4 disc image to an HFS+ formatted flash drive, that has been set up with Apple Partition Map you will be able to (with some OF trickery) boot from USB on a PowerPC Macintosh.
I love SuperDuper from ShirtPocket Software. Excellent util for block-cloning disks and images. In my example, we’re going to say the poison of choice is Tiger, cause Tiger is awesome and I like it. You can do whatever you want, but this is my tutorial.
Prepare your flash drive. Format it with 1 partition, and use Apple Partition Map. Don’t use MBR or GPT. Filesystem must be HFS+ (Mac OS Extended). Don’t enable journaling, and don’t make it a case-sensitive volume either. That would just anger the Mac gods.
Let’s grab a Tiger disc if you don’t already have an image. You will want a read-only image in DMG format. Toast, ISO and CDR are wonky for this – try it, but you may have mixed results because of funky resource fork things that don’t play nicely.
Neat – you have a nice clean DMG hanging out somewhere now. Load up either SuperDuper or plain old Disk Utility – we’re going to restore that DMG to the flash drive. I like SuperDuper because sometimes Disk Utility messes up the magic that makes OS X boot nicely.
Your target machine should be off at this point. Connect your flash drive, and disconnect ANYTHING that isn’t an essential peripheral. Don’t plug the flash drive into a hub – that would be nuts and probably cause bad things to happen while starting up.
Boot into Open Firmware (Cmd+Opt+O+F at the startup sound.)
List all devices with dev / ls and find your USB device.
Your USB flash drive will probably be at a path like
Alias that path to something less awful by a command like
devalias ud /pci@f2000000/usb@1b,1/hub@1/disk@1
You then should be able to boot the “ud” device you just made an alias to. Use a command such as:
May need to fiddle with command syntax – specifically the number. In my example, “3” refers to the System folder being on the third partition of the device.
If all that fails, then finally you would want to force the Mac to read the CHRP script manually:
If you get a prohib symbol after finding the right boot command, that means you either 1) messed up while creating the flash drive, or 2) the system software won’t work with this Macintosh, or finally, 3) you just pointed to the wrong root partition.
Have fun not buying loads of blank DVDs and CDs.