Boot PowerPC Macs via USB 2.0 drives

First off, I have tried and tried again over the years to boot various PowerPC Macs via a USB2 disk. Thankfully, somewhere about the time the iMac G5 with the ambient light sensor (ALS) was released, Apple tweaked their Open Firmware, which allowed us to boot PowerPC Macs from USB2 drives.

Machines that I have tested this hint on and made it work are:

iMac G5 w/ ALS
iMac G5 w/iSight (thanks to the eager user who emailed me)
12" PowerBook 1.3GHz

Without further delay, here's the process to follow.

Note: As with all hints that have to do with Open Firmware, proceed at your own risk! I have not experienced a problem and I don't see how this hint could render your Mac useless, since the default can always be recovered by resetting the SMU.

Here's what you need to do...

You need a USB2 drive with an OS X system installed (I am using 10.4.3, though any I think will work as far as what the machine can boot). As you know, there are many different ways of getting a system on a USB drive; contact me if you have any questions on how to do that, or search macosxhints.com for that information.
Connect the drive to your machine, and find out which partition the OS X system is installed on. I usually find this by going to Disk Utility and looking at the info for the partition on the USB disk with OS X. That is, disk2s3 is usually for a USB disk with no OS 9 drivers installed that is the second disk disk. disk3s9 might be a USB disk with OS 9 drivers that is considered the third disk. There are other ways of finding this out, but in my case, my disk is disk2s3 (the 3 on the end will come into play soon).
Start up the machine in Open Firmware (this is the fun part). Hold Command-Option-F-F right after the machine is turned on.
Here is the moment of truth. If this step does not work, I have had very limited success getting a machine to boot off USB2. In Open Firmware, type devalias, and you should get a list as output. In this list, look for ud, usually below where you see hd (ud is "USB Disk," I presume). If found, it will usually have beside it /pci@f2000000/usb@1/disk1, or something similar. Again, if you see this, I have not had this fail yet.
Now type printenv boot-device, which will usually get you output of boot-device hd:,\\:tbxi. (See where this is going yet?)
Type setenv boot-device ud:3,\\:tbxi where the number after the colon corresponds to that partition number we found in step two. You should get an ok back.
Type printenv boot-device, and you should see the change displayed already. Something like:
```
boot-device        ud:3,\\:tbxi        hd:,\\:tbxi"
```
Type mac-boot and cross your fingers.

And now some more fun, there is a Unix script that can be written to enable this, because after all we are only changing a nvram variable. The command would be similar to this:

nvram boot-device ud:3,\\\\:tbxi

Now this looks a tad bit different then what we typed in Open Firmware, but that's because we have to escape the two backslashes, each with a backslash of its own.

If this fails, there is a remote possibility that you can still boot off of USB2, but you may need to substitute ud for /pci@f2000000/usb@1/disk1, or something similar. If the firmware cannot list the contents of the drive, it seems it cannot boot off of it.

As you should know (thanks to the owner of the iMac G5 w/iSight for letting me know I should mention this), USB2 booting is not supported, therefore you should remember OS X has no support for booting USB 2 and the firmware has no support. So in System Preferences, the USB disk will not be shown as a bootable drive. In the optional boot menu (reached by holding down the Option key during boot), it also will not show.

So the two ways that I know how to enable it are through terminal by using the nvram command, and directly in Open Firmware. Hope this hint helps someone out there. I figured my trick was shot as soon as the Duo Core machines came out, but I now realize there are quite a few people with PPC Macs that might be able to use this hint.

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The following comments are owned by whomever posted them. This site is not responsible for what they say.

Boot PowerPC Macs via USB 2.0 drives
Authored by: CHerbold on Tue, Mar 7 2006 at 7:51AM PST

"Command-Option-o-f" to boot into Open Firmware.

Boot PowerPC Macs via USB 2.0 drives
Authored by: kL on Tue, Mar 7 2006 at 1:24PM PST

Why set nvram variable? I've had open-firmware based Pegasos PPC and it simply had boot command, so instead of:

setenv boot-device ud:3,\:tbxi

should be enough to write:

boot ud:3,\:tbxi

[ Reply to This | # ]

Boot PowerPC Macs via USB 2.0 drives
Authored by: Skeeve on Sun, Aug 17 2008 at 8:15AM PDT

Yes! That's sufficient. Except that I have to enter 2 instead of one backslash to get this to work.

Boot PowerPC Macs via USB 2.0 drives
Authored by: mmacho on Tue, Mar 7 2006 at 2:43PM PST

I have the next list of magical boot key sequences:

Key Combination -- Effect
mouse down -- Eject removable media ( I think Boot ROMs prior to 2.4f1 excluded the CD drive )
opt -- Bring up OF system picker on New World machines
cmd-opt -- Hold down until 2nd chime, will boot into Mac OS 9 ?
cmd-x (or just x?) -- Will boot into Mac OS X if 9 and X are on the same partition and that's the partition you're booting from.
cmd-opt-shift-delete -- Bypass startup drive and boot from external (or CD). This actually forces the system to NOT load the driver for the default volume, which has the side effect mentioned above. For SCSI devices it searches from highest ID to lowest for a partition with a bootable system. Not sure about IDE drives.
cmd-opt-shift-delete-# -- Boot from a specific SCSI ID # (# = SCSI ID number)
cmd-opt-p-r -- Zap PRAM. Hold down until second chime.
cmd-opt-n-v -- Clear NV RAM. Similar to reset-all in Open Firmware.
cmd-opt-o-f -- Boot into open firmware
cmd-opt-t-v -- Force Quadra AV machines to use TV as a monitor
cmd-opt-x-o -- Boot from ROM (Mac Classic only)
cmd-opt-a-v -- Force an AV monitor to be recognized as one
c -- Boot from CD. If set to boot to X and no CD is present, may boot to 9.
d -- Force the internal hard disk to be the startup device
n -- Hold down until Mac logo, will attempt to boot from network server (using BOOTP or TFTP)
r -- Force PowerBooks to reset the screen
t -- Put FireWire machine into FireWire Target Disk mode
z -- Attempt to boot using the devalias zip from first bootable partition found
shift -- (Classic only) Disable Extensions
shift -- (OS X, 10.1.3 and later) Disables login items. Also disables non-essential kernel extensions (safe boot mode)
cmd -- (Classic only) Boot with Virtual Memory off
space -- (Classic only) Trigger extension manager at boot-up
cmd-v -- (OS X only) show console messages during boot
cmd-s -- (OS X only) boot into single user mode

Did not work simply 'z'?

Boot PowerPC Macs via USB 2.0 drives
Authored by: EvanE on Tue, Mar 7 2006 at 5:16PM PST

Congratulations - you also have the magical ability to make a useful hint unreadable. Wrap your text next time.

Boot PowerPC Macs via USB 2.0 drives
Authored by: jacobolus on Wed, Mar 8 2006 at 2:17AM PST

Yeah, Rob, can you do something about this please!!??

Option Key
Authored by: vandil on Wed, Mar 8 2006 at 5:57AM PST

How about just booting the Mac with the Option key held down and let OF (in GUI mode) discover all the bootable devices itself, them simply clicking on your USB2 drive (if it appears onscreen bootable) and clicking the mac-boot arrow?

Option Key
Authored by: CHerbold on Wed, Mar 8 2006 at 10:18AM PST

Because booting to USB is not supported through OF it will not show up in the GUI boot screen.

Option Key
Authored by: johnsawyercjs on Sun, Mar 18 2007 at 1:06AM PDT

Not true in all cases. Many USB drives will show up in Startup Manager (what you get when you hold down the Option key at startup), and you can boot from them as long as they're running OS 9 (for Macs that can boot into OS 9), or 10.4.x (at least 10.4.6--I haven't tried earlier versions). See more in my post below.

Option Key
Authored by: johnsawyercjs on Wed, Apr 23 2008 at 1:58PM PDT

That should be OS 10.4.3 and later.

Boot PowerPC Macs via USB 2.0 drives
Authored by: Ebonweaver on Tue, May 16 2006 at 4:05PM PDT

I can confirm that this works under a 1.8ghz iMac G5
It was actually pretty cool to boot a machine from a 2gb flash drive (I trimed a copy of 10.4.6 down to 700mb and cloned it)

It does NOT work under a dual 2ghz G5 tower, or 1.67ghz 15" Powerbook. They don't have the "ud" device in firmware and I couldn't force it to boot from a USB line using similar techniques. As the above author mentioned, nothing shows the drive on these units, it's just not being scanned for.

I suspect only the iBook and iMac line have the "ud" device available which makes this possible, so no Powerbook or G5 is USB bootable. As a side note, once you add the "ud" boot device any time the mac boots up there is a momentary lost folder icon before it fails over to the internal hard drive.

Interestingly, older macs that only have USB 1 ARE USB bootable with no real tricks involved. While you can't select the USB device in the Startup Disk preference pane, you can simply option boot and choose the drive. It's slow of course, but it works.

The very interesting tidbit here is that the "ud" device does not show up in firmware on these old macs that boot from USB. This implies to me that Apple had the function in the firmware on the old machines to look at USB for bootable devices, then removed it when they added USB 2. This of course makes no sense as that's when you would have wanted it as it became truly useable with the higher speeds. Why the iMac and iBook have a partial ability to look for but not use such a device is very odd.

At any rate, I feel like every Apple support person and techy out there needs to flood Apple with requests to patch their firmware to allow USB booting, because it seems it should be a simple firmware update to allow it based on the above information.

Boot PowerPC Macs via USB 2.0 drives
Authored by: Woofb on Tue, Sep 5 2006 at 11:20PM PDT

There may be reasons not to boot from flash often.

I'm a switcher, and I remember looking up how to boot from USB if the bios supports it, and e-mailing somebody to ask why their shareware program didn't support booting from a flash drive.

They said flash drives can't handle quite as many read/write cycles as a hard drive, so it's not recommended for them to go through the hammering a boot sequence gives the drive as it creates and deletes files all over the place. (I have no idea how this translates to the Mac, but it seems to be common-sense that large modern operating systems do A Lot Of Stuff before you see your login, so I'd expect many tiny files to be created and deleted in XP and Tiger).

This suggests that booting from a flash drive all the time (for security or portability reasons) would not be good, because after a matter of weeks or months it might give up the ghost.

It occurs to me that this might mean a flash drive is a really good choice for a minimal system 'rescue disk' in the way people used to keep a boot floppy somewhere. This is because a flash drive seems to be noticeably more robust than floppy, zip, cd-r or hard drive, as far as keeping it lying about and expecting it to work is concerned. I haven't actually tried this myself (I tend to clone the main disc to the firewire disc and hope it all works), but it's an idea.

(Sorry if everyone already knows all this, but it's probably worth pointing out in case anyone's just thinking about it and falls foul of this)

[ Reply to This | # ]

Boot PowerPC Macs via USB 2.0 drives
Authored by: junk on Tue, Jul 4 2006 at 12:29PM PDT

Hi,

I'm a PowerBook 12" 1,5 Ghz user

I would like to know if this trick will work for another PB 12" 1,5 Ghz user ??

I try the trick but it doesn't work ...

I can't find "UD" when i type devalias ....

There is another way to do the trick ???

Thanx.

Boot PowerPC Macs via USB 2.0 drives
Authored by: raymondlewisjone on Fri, Dec 15 2006 at 11:43AM PST

Hello,

Awesome Hint!!!!!
I use iMac 17" 1.8Ghz G5 (PPC), and this hint worked perfectly.

Interesting hint you should also try after duplicating your startup disk to restore those invisible items that have become visible:
http://www.macfixitforums.com/printthread.php?Cat=&Board=tiger&main=745867&type=thread

Also, for anyone who is trying, but cannot boot from USB2.0. Remember to uncheck OS9 Drivers when partitioning(erasing) your destination disk. I tried and tried with no success untill I did this. Stupid of me, It's a small detail.

THANKS FOR THE GREAT INFO!!!!!!!!!!

Boot PowerPC Macs via USB 2.0 drives
Authored by: Xris on Mon, Jan 15 2007 at 11:50AM PST

Hi! Great Hint, saved me some bucks too!

I read this hint a couple of months ago and could not get it to work on my eMac 1.42/512Mb. I first tried the boot menu, and got nowhere. I then went into OF and imediately saw I had no "ud" alias. I don't exactly recall what version of Tiger I was running at the time, 10.4.6 or 10.4.7 maybe.
Now, just this week, I tried it again... with success.
I still had to go into OF and type "boot ud:##,\\:tbxi", but no problems... well so I though.
First I tried a clone of my Tiger Install DVD, no luck. I got the grey Apple and then the "no entry" (circle with a diagonal line across.). The I tried a clone of a fresh install onto a local partition. No luck. A Panther install CD clone. Nope. An x-support bootable clone. Nope.
In fact, my first sucess was with an e-drive made with techtool(??) and then with a Tiger system that I had a backup from another system. I do not see the connection or why these particular partitions/drives worked.
Any ideas?
I tried looking at the "blessed" info from the successfull boot volumes but they didn't show up any differences fron the rest. I even tried to bless the volumes I wanted to get working, but got nowhere.
In my case, I definitely believe that updating to 10.4.8 (or maybe a security update) put the "ud" in my OF. Has anybody else had this happen?
Also, I have on occasion delved in to the OF for various reasons, and somewhere I read that you could write your own "alias" into OF that could be mapped to a startup key (ie: "u" for usb, like "c" for CD). I'll see if I can track it down again.

Boot PowerPC Macs via USB 2.0 drives
Authored by: ShdwFlame on Tue, Feb 20 2007 at 8:34PM PST

I have Mac OS X 10.4.8 but I still don't have "ud" in my OF. However, I have a lot of "usb"s listed. Does anyone else have this problem?

Boot PowerPC Macs via USB 2.0 drives
Authored by: Xris on Tue, Jan 16 2007 at 12:29PM PST

Just in case, had anyone seen this

http://docs.info.apple.com/article.html?artnum=58430

Boot PowerPC Macs via USB 2.0 drives
Authored by: johnsawyercjs on Sun, Mar 18 2007 at 1:01AM PDT

Best I can tell, from my experience and that of people posting to the similar hint at www.macosxhints.com/article.php?story=20061017084322177:

• USB 1.1 and 2.0 ports/drives have always booted OS 9, on any Mac that can boot into OS 9.

• Macs up through the Powerbook G4 1.33 GHz, and at least some desktops up to and including the same vintage, and maybe a few later pre-Intel PPC Macs (not sure why not all the pre-Intel PPC Macs), will boot SOME USB drives from USB 1.1 and 2.0 ports/drives into OS 10.4.x (at least 10.4.6 and above--I didn't try earlier versions)--NOT OS 10.3.9 or earlier. Older Macs may need their firmware updated to the last version available for that Mac model, and not all USB drives might boot. Some USB drives will appear in Startup Manager (what you get when you hold down the Option key at startup), and others won't; when they don't, reset the Mac's PRAM, NVRAM, and Open Firmware (see my steps in the other Macfixit post I cite above), and that may allow some of them to appear in Startup Manager.

Boot PowerPC Macs via USB 2.0 drives
Authored by: johnsawyercjs on Wed, Apr 16 2008 at 7:45PM PDT

Further refinement I just came across in my notes, on the system requirements to boot from Macintosh USB ports: OS 8.6 through 9.2.2, and OS 10.4.3 and later. OS 8.6 - 9.2.2 might need the last of whichever versions of the USB extensions that each of these System versions supports (for OS 9.1 through 9.2.2, USB 1.5.6 is the preferred version; OS 9.1 and later don't need the extension "USB Mass Storage Support", especially since it sometimes freezes Macs running OS 9.1 - 9.2.2 that are trying to boot from USB), though other details as to the proper combination and versions of USB extensions under OS 8.6 - 9.2.2 is screwy, and too lengthy to post here, especially since we're dealing with OS X anyway.

The first Macs to support USB booting, are the first slot-loading iMacs (including the 350 MHz model with no Firewire ports), and the Firewire Powerbook G3. I've even booted OS 10.4.11, from a USB 2.0 flash drive, on a Mirrored Drive Doors G4, from a USB 2.0 PCI slot card, with no special tricks, Open Firmware modifications, etc.

Boot PowerPC Macs via USB 2.0 drives
Authored by: dancriel on Thu, Feb 7 2008 at 11:08PM PST

Don't forget that to go back to booting from your internal drive, follow the same steps but type setenv boot-device hd:,\\:tbxi in step 6 instead.

This worked in 10.5.1 on my iMac G5 ALS using a USB 2.0 drive with a partition that holds a clone of my main startup drive (the internal drive) made using rsync and the magical "bless" command instead of SuperDuper! or Carbon Copy Cloner

Boot PowerPC Macs via USB 2.0 drives
Authored by: nashj4u on Wed, Jun 11 2008 at 9:00AM PDT

CHerbold-ive got a 1.6 ghz imac G5,followed ur instructions several times and still no use.It just wont boot to install da leopard from my external 2.0 drive.Am i missing sumthing ? can u plzz help me out.thanx in advance

Boot PowerPC Macs via USB 2.0 drives
Authored by: nakae on Thu, Jun 12 2008 at 9:40AM PDT

I tried booting from an external hard drive using the suggestions from another post and superduper and had absoluetely no problems. I have a G3 Imac running os x 10.4.11. The only thing I did notice is that the upload was incredibly slow (like 11 hours for a full clone of my HD slow??)

Any suggestions? I think it might be running at a USB 1.1 speed not 2.0. Any patch or hint to change the speed so that my mac recognizes the cable as 2.0??

Boot PowerPC Macs via USB 2.0 drives
Authored by: s1223 on Wed, Jun 18 2008 at 11:26PM PDT

I have an iBook G4 (the last model before it was discontinued) running Leopard 10.5.3 and I cloned my drive using SuperDuper to my usb drive and it works! And I don't find it as slow as some people say. It actually works quite well.

Boot PowerPC Macs via USB 2.0 drives
Authored by: gabester on Thu, Jun 19 2008 at 7:29AM PDT

I think only the G4 PowerMacs with Firewire 800 built-in and Macs with Airport Extreme have chipsets that support USB 2. So a G3 iMac will only ever have USB 1.1 capable hardware, maxing out at 1.2MB/s speeds.

Boot PowerPC Macs via USB 2.0 drives
Authored by: Kopachris on Sat, Nov 15 2008 at 8:55PM PST

Thank you! This is so awesome, since I can't non-destructively resize my partitions, I used CCC to make a backup so I can reformat my HD and restore my data. The restoration wouldn't quite be the same without this. I'm posting this reply from my 1.67GHz 17" PowerBook G4 booted to a 500GB Western Digital MyBook. Totally awesome!

Boot PowerPC Macs via USB 2.0 drives
Authored by: like2race on Wed, Dec 16 2009 at 11:24PM PST

It works using " boot ud:3,\\:tbxi " instead of " setenv boot-device ud:3,\\:tbxi " on an iBook G4 PPC. I am very happy now. THANK YOU.

Boot PowerPC Macs via USB 2.0 drives
Authored by: atonaldenim on Wed, Jan 13 2010 at 11:02AM PST

Sadly this doesn't work on a very late model Powerbook G4 15". The activity light on the USB drive never flashes, and the ud device doesn't show up in Open Firmware. I made sure the drive was partitioned APM and the System folder was blessed, I think there must just be a lack of support for USB booting in this particular hardware configuration.

Boot PowerPC Macs via USB 2.0 drives
Authored by: psamyiad on Wed, Feb 3 2010 at 7:38PM PST

Outstanding tip.

Worked an absolute treat on late Powerbook G4; 1.67, 2gb ram, 148g HD.

Upgrading to 10.5 on that machine right now. Thanks ever so much for the advice.

(Atonaldenim, I'm assuming this is a similar model to yours as the 1.67's were the latest release... I guess you could try using different flash disk?) I'm no expert but I hope this will give you some hope that it is possible...

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