Why USB? Why not FireWire?

I only have USB enclosures at my dispoal currently.

To be perfectly honest, I don't know if OpenFirmware will let you do that. If you connect a USB mass storage device and boot the machine into OF, can you at least find it in the OF dev tree and list the contents? If you can, you have at least a shot at this. Unfortunately, trying this out probably requires more a keyboard than it appears you have.

Is there any other way to get into OF other than cmd-opt-O-F?

Without an option key the standard method won't work

There's this hint:

http://www.macosxhints.com/article.php?story=20060301112336384

But you'll need a keyboard. Even if you unplug the motherboard IDE, Open Firmware doesn't search the USB bus for volumes when it tries to boot, so you'll just have to borrow a USB keyboard or take the drive out of the USB enclosure.

Hmm. Would a USB PC keyboard work? Would the ALT key on a PC keyboard work as an Option key on a Mac (since they occupy the same physical key on certain Mac keyboards)?

Are ADB to USB adapters made? Would that work? I have an old ADB keyboard for my Classic II.

I've used a PC keyboard to use Mac shortcuts in the finder. The keys might be slightly rearranged but it should work. First boot into the finder and open keycaps or "keyboard or character viewer" in OSX. Then you can accurately see what button hits which apple key.

Yes, a typical PC keyboard would work fine. They usually have the two meta keys (option and command or Windows and alt) reversed, although in OS X you can use the Keyboard control panel to swap them.

ADB to USB exist, but they'd be a lot more expensive than a USB keyboard. I still have a few at work - we used to use them for the dongles for certain software.

Great. Thanks guys! I'll give the PC USB keyboard a shot and see if it works.

I tried everything under the sun to get my MDD FW800 to boot off of USB but it absolutely refused, it would start to load the OS installer and I would get the gray "Stop" sign each time. I tried it with a few different drives.

I finally borrowed an old FW drive enclosure from one of my friends, used one of the HDs I had tried in the USB enclosures, and it booted up in target disk mode no problem.

Apparently MDD FW800 systems can't be booted off of USB.

I tried everything under the sun to get my MDD FW800 to boot off of USB but it absolutely refused, it would start to load the OS installer and I would get the gray "Stop" sign each time. I tried it with a few different drives.
I finally borrowed an old FW drive enclosure from one of my friends, used one of the HDs I had tried in the USB enclosures, and it booted up in target disk mode no problem.

Click to expand...

Was the drive SATA? Is that why you couldn't just connect it to the internal IDE bus?

How do you use a Firewire hard drive to boot into Target mode? That part I don't understand at all...

Apparently MDD FW800 systems can't be booted off of USB.

Click to expand...

I wouldn't say "can't", but I'd agree that it's non-trivial.

I just held down the F key with the firewire enclosure attached and it booted from the enclosure.

As far as not being able to boot off of USB, if you can think of any other methods I'd be interested in trying them, but I honestly don't think it's possible. It doesn't show up as a valid boot option from the boot menu. If one goes into OF and tells the Mac to boot from USB it will start to load the installer for the OS but you end up with the gray "Stop" sign. It did this with 3 different drives in 2 different enclosures that are completely different brands so I don't think it was the enclosures or the drives. It def. wasn't the drive since I took the exact same one out of the USB enclosure, but it in the FW enclosure, and it booted up just fine.

I've always been under the impression that it's generically unsupported to boot OS X on any PPC machine over USB, even though the older machines could boot OS 9. (Once upon a time I successfully pared down a 9.2.2 system file to fit on a 64MB USB key and booted my 867Mhz Titanium with it, just for shnitz and giggles.)

That said I have *heard* of it being done (At least on G5s and Aluminum G4 Powerbooks), but I think one of the keys to all the accounts is it's only possible to fake the machines into booting an existing "working" OS X partition cloned en-mass to a USB drive. You talk about "loading the installer" when booting from the attached drive... what are you doing, attempting to boot an OS X CD/DVD install image DD'ed onto a disk? (And it is possible that the success stories may well only apply to newer machines/laptops. Apple used several different motherboard chipsets in the late-G4 era, and the DDR-memory-equipped PowerMacs used several confusing variants with different capabilities.)

Using Disk Utility I restored a DMG I made of a 10.5.6 retail DVD to a HD in a USB enclosure. Every time I tried to boot the MDD FW800 using that drive off of USB it crapped out on me, swapped the drive into a FW enclosure and it worked like a charm.