How to reinstall OS9 on a computer already running 10.4

stephgreene

Registered
I have a Quicksilver G4 that is running 10.4 and I need to replace the OS with OS9 and I'm trying to a clean install (this computer is running a piece of equipment that needs software that only runs in OS9 and running it in classic mode won't work). I'm trying to boot from the OS9 CD but the computer won't start from the CD - when I hold down the C key it will try to use the CD but I get the alternating folder with the classic mac happy face and question mark. When I hold down the option key only the current HD with OSX shows up, and not the CD. It's entirely possible, since this disc is 10+ years old, that the install CD has something wrong with it and is no longer good. Can anybody offer some advice?

Thanks!
 
I think I should mention that this G4 originally came with OS9 and was upgraded to Jaguar, then Panther then Tiger over the last few years. So it is capable of running OS9.
 
What's the problem? MacOS X 10.4 is designed to allow dual-booting with MacOS 9 on PPC-based Macs like your G4. Why clean install?

I guess I don't understand what you mean by "the OS 9 CD." There are many OS 9 CDs and still many other MacOS 9-based Restore System discs. What do you mean?
 
Is your OS 9 disk the same one that came with your PowerMac originally?
The Quicksilver would need 9.2 or 9.2.2, I think.
9.0 or 9.1 may not boot your Mac, for example.
The OS 9 version number would be on the disk label.
 
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