Home > Mac, Tech Tips, Technology > Directly Install a shop copy of Leopard on an iMac 700MHz (or even a stock, unmodified G4 Cube!)

Directly Install a shop copy of Leopard on an iMac 700MHz (or even a stock, unmodified G4 Cube!)


imacg4-leopard

Yes, despite Leopard being limited to 867MHz G4 processors and faster, you can pretty much install Leopard on any G4 Mac with an AGP graphics card. (OK, so the picture above is a phtoshopped image of a 1GHz model, but you get the idea.)

So, I decided to try it out and reinstall Leopard from scratch on my shiny “new” iMac with its rip-roaring 700MHz processor, 40GB hard disk and 640MB RAM.

To cut a long story short, it can be done and ridiculously easily!

  • Reboot the iMac
  • Hold down the Cmd-Opt-O-F keys. Instead of the usual white screen and grey Apple logo, you’ll get a black screen with a white Open Firmware prompt.
  • This is NOT a regular BASH prompt, so don’t be tempted to try anything!
  • Insert the shop copy of the Leopard DVD. (If it’s already in the drive, that’s fine, too).
  • Type the following lines in exactly as shown below. After pressing Return, you should see “ok” to signify that the command was understood. If at any time you have any doubt, just reset the Mac and start again since these settings are cleared after a reboot.

For your iMac, G4 Cube etc, type this:

dev /cpus/PowerPC,G4@0
d# 867000000 encode-int " clock-frequency" property
boot cd:,\\:tbxi
  • The install will continue.

I haven’t tried this below, but…
If you have a dual CPU computer, use the following:

dev /cpus/PowerPC,G4@0
d# 867000000 encode-int " clock-frequency" property
dev /cpus/PowerPC,G4@1
d# 867000000 encode-int " clock-frequency" property
boot cd:,\\:tbxi
  • The install will continue.

Remember this hint does not confer any magical speed increase, it just lies to the Installer! Also, a reboot clears this tweak, But Leopard will continue to run, once installed.

Obvious point but… If you install a new OS, you’ll in all likelihood LOSE SOME OR ALL OF THE CONTENTS OF THE DRIVE. BACKUP FIRST!

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Categories: Mac, Tech Tips, Technology Tags: , , , ,
  1. Will Salomon
    July 9, 2013 at 8:00 am

    Unfortunately, the script as above did not work. However, changing the last line to:

    mac-boot

    does work.

    See http://lowendmac.com/osx/leopard/openfirmware.html

  2. Denis
    November 15, 2013 at 6:05 am

    Hi, cannot do this with the internal CD drive. How do I direct it to an external USB CD drive?
    What do I type instead of boot cd:,\\:tbxi
    Thank you

  1. April 21, 2009 at 1:18 pm
  2. September 25, 2011 at 5:13 am

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