MacOS X cannot be installed on PowerMac G4

[outwithspam]

Hi,
After hours of work, I finally figured out how to boot from a Leopard 10.5.6 image on my PowerMac G4AGP in order to upgrade my system from 10.4.11. Didn't seem to work from a USB stick so since I had 3 internal HDs in the unit, I decided to use one of them to put the installer image. Was able to boot into the image but when I start the install I get the message "MacOS X cannot be installed on this computer". The processor speed is 450 MHz andI checked and have the required 512 MB of RAM and version 4.2.8 of the firmware, have reset the PRAM and warned all low-flying planes, to no avail. I was under the impression that I could install Leopard on this computer. Was I wrong or what am I missing?

 

[velocityg4]

Leopard requires an 867Mhz. To get it to install. You can spoof it in Open Firmware. This doesn't actually change the speed. Just the reported speed for that boot. Once you restart the value goes back to normal. I know this works for the installer disc. I tried by starting the installer from the OS. I suppose you'd have to do it twice. When starting the process and when the installer restarts the computer.

Once Leopard is installed. It won't care about Mhz anymore.

Fooling the OS X 10.5 Leopard Installer with Open Firmware | Low End Mac

Abbreviated excerpt:

Cmd-Opt-O-F at boot

For single CPUs, use the following three lines:

dev /cpus/PowerPC,G4@0
d# 867000000 encode-int " clock-frequency" property
boot cd:,\\:tbxi

For dual CPUs, use the following five lines:

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

 

[outwithspam]

Leopard requires an 867Mhz. To get it to install. You can spoof it in Open Firmware. This doesn't actually change the speed. Just the reported speed for that boot. Once you restart the value goes back to normal. I know this works for the installer disc. I tried by starting the installer from the OS. I suppose you'd have to do it twice. When starting the process and when the installer restarts the computer.

Once Leopard is installed. It won't care about Mhz anymore.

Fooling the OS X 10.5 Leopard Installer with Open Firmware | Low End Mac

Abbreviated excerpt:

Cmd-Opt-O-F at boot

For single CPUs, use the following three lines:

dev /cpus/PowerPC,G4@0
d# 867000000 encode-int " clock-frequency" property
boot cd:,\\:tbxi

For dual CPUs, use the following five lines:

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

Thanks for your clear and precise answer. I had read about this but was not sure it would work, your confirmation that is worked for you gives me the confidence to try.

 

[velocityg4]

Thanks for your clear and precise answer. I had read about this but was not sure it would work, your confirmation that is worked for you gives me the confidence to try.

You're welcome. It did fine on my 466Mhz. When I did this a long time ago.