Installing Mac OS 9 on a legacy Mac that's already running Mac OS X

I write music in Midigraphy - a native OS9 application; problem is, it was never ported to OSX. Even under classic mode, the audio has latency and is not a serious option for composing. The Midigraphy clone MidiSwing runs on Java (yuck), and works too differently to be useful, especially if you have thousands of hours of muscle memory using Midigraphy.

It seems Apple was pushing hard for people to forget OS9, and so it’s difficult to get this to happen. After many hours of torturous research, I was able to install Mac OS9 on a fresh Titanium Powerbook G4. I wanted to use the full capacity of the SSD I bought for this computer, and so did not want OSX installed at all.

What you need:

How to achieve this in a few simple steps:

  1. Boot the legacy Mac using the OSX install disc
  2. Using Disk Utility (look under the menus) wipe the target drive while installing Mac OS9 drivers
  3. Boot the legacy Mac in Target Disk Mode
  4. Dump the contents of the mounted general purpose build of OS9 into the legacy Mac (but NOT the mounted disc image itself)
  5. Boot legacy Mac again from the OSX install disc, and use the startup volume feature (look through the menus) to choose the OS9 build you just dumped in there
  6. Reboot while holding down the eject button to eject the OSX install disc
  7. Rejoice and enjoy OS9 without any trace of OSX eating up your precious disk space