Late 2006 iMac booting from USB with no internal HDD?

Discussion in 'iMac' started by Mintimperial, May 28, 2015.

  1. Mintimperial, May 28, 2015
    Last edited: May 30, 2015

    Mintimperial macrumors regular

    Sep 27, 2012
    So basically Im trying to save this 2.16Ghz Intel Core 2 Duo G5 A1207 iMac I found for sale for £10. ($15USD)

    it had no internal HDD (presumably removed for security reasons) and the PSU was blown.

    Replaced the PSU for a cheap used unit and now the machine turns on at least

    I *was* looking to replace the internal HDD, but on inspection the SATA data connector on the logic board has been damaged by some heavy handed oaf. (one of the pins snapped off)

    I have a usb 240GB SSD drive that i would like to run the machine on. is this possible?

    Can someone point me to a tutorial of how i go about getting OS X onto the external HDD and booting from it. Is this even possible with No internal HDD?

    I have a macbook pro, i was hoping to make some sort of USB recovery partition using that?

    Any help greatly appreciated.
  2. keysofanxiety macrumors G3


    Nov 23, 2011
    On the PPCs you couldn't boot from an external USB device, if memory serves. I had a world of problems trying to install Tiger on a 1.67GHz G4 ... basically I mounted the Tiger installation to an external USB drive and had to do a number of things to boot from that, it was a real pain ...

    I'm at work at the moment but when I head home I'll check over my documents on my computer as I'm sure I've written down how I did it somewhere.


    Hokey dokey, thankfully I had the instructions written on my work computer (as I brought it in to do it on at work). I'm assuming you've got another Mac to hand as you'll need to mount the OS install onto that.

    My written instructions are below but I'm not sure how helpful this is buddy, you may need to have a heavy slice of intuition and luck. I kinda wish I took screenshots :(

    1) Format pendrive/external HDD to be PowerPC Compatible in Disk Utility
    2) Mount the OS installation to the pendrive (using the ‘restore’ function)
    3) On the PPC Mac, hold down Cmd+Alt+F+O to get into the open firmware.
    4) Type ‘devalias’, and look for anything that says ‘ud’. This would be the external drive you're trying to boot from.
    5) Type ‘devalias ud /exactly_what_it’s_called’ (make ud equal to what’s in the devalias). It usually looks like pciblahblahblah.
    6) Verify the disk (dir :ud3,\). If that doesn’t work, try ud2 or ud1. This’ll make sure that all the files are as they should be.
    7) Find the CoreServices folder (dir ud:<number>,\System\Library\CoreServices)
    8) Then boot from it (boot ud:<number>,\System\Library\CoreServices\BootX)


    Just to add to the above, that was on an install for Tiger (OS X 10.4), so I'm not sure if Leopard has the \System\Library\CoreServices file for the install.

    Please can you take photographs of any problems you run into, quote my reply, and I'll try to see if the cogs in hazy memory will clock back into life so I can be a little more helpful :)

    Speak with you soon!
  3. truettray macrumors 6502


    Sep 7, 2012
    I doubt you will see the SSD provide any real speed over USB 2. If you plan on actually using this iMac, you would probably be better off booting off of a FireWire drive, which is also supported natively. That also frees up 1 valuable USB port.
  4. keysofanxiety macrumors G3


    Nov 23, 2011
    You're right Truetray, the G5s can boot from USB! I had no idea. It's just the G4s that can't.

    So OP, please ignore my essay -- at least the instructions are there if you ever need help with a G4 iMac :D :eek: :D :eek:
  5. Mintimperial, May 30, 2015
    Last edited: May 30, 2015

    Mintimperial thread starter macrumors regular

    Sep 27, 2012
    Hi all,

    Pretty pleased with myself. Got everything fixed and working as planned!

    Replaced the psu for one i grabbed on ebay for £21.

    Using the 240Gb SSD i had lying around, I made a base bootable image of snow leopard 10.6.3. Booted straight from usb no hassle.

    Then updated to 10.6.8, found some RAM in a local second hand store for £5 to upgrade to 2gb then upgraded from the app store to Lion which i had purchased previously for my old MBP.

    Now running 10.7.5 Lion (the most up to date OS X this will run)

    Oh and I added a wireless magic mouse and aluminum keyboard and trackpad which i had which were not being used.

    Just need to find the rest of the missing case screws and a ram cover to complete it.

    Running sweet right now! :)

    Total cost for this iMac was £36, as the SSD and keyboard etc I already had lying around doing nothing.

    Pretty pleased with myself and a decent iMac saved from certain death!! :D

    Attached Files:

  6. Mintimperial thread starter macrumors regular

    Sep 27, 2012
    Few more pics!

    Attached Files:

  7. Mintimperial thread starter macrumors regular

    Sep 27, 2012
    Wasn't necessarily stuck on using an SSD, its just that I had this one left over from another project, so it saved buying another disk.

    May get a firewire enclosure for it, or more likely just fix the data connector on the logic board, probably solder the wires directly from the cable.


    Thanks for your hep anyway! I appreciate the effort. I should have mentioned initially it was an intel machine.

Share This Page

6 May 28, 2015