Trying to install OS 9 on classic G4

I find no Dual 1.13GHz G4 models listed.

Power Mac G4: How to Differentiate Between Models

Power Mac G4: How to Differentiate Between Models, Part 2

Perchance has this machine had a processor upgrade? If so, what was its original processor speed?

Are you using a retail OS 9 installer or the Install/Restore disc that came with the Mac. Many of the G4 models came with a special version of OS 9 higher than OS 9.0. Therefore you need to use the OS 9 version on the Install/Restore disc.

If you just want to run OS 9 apps in classic mode, copy the System Folder from another Mac that has OS 9.1 (or better with 9.2.1 or 9.2.2) installed. A USB thumb dive works great for this. Transfer the folder to your Mac. It won't interfere with your OS X system which is in a folder titled System.

 Cheers, Tom 😉

Is this a model that has mirrored drive doors? If so, it's either a dual 1.0 or 1.25 Ghz model and you can install Mac OS 9 on it, but it requires the original discs that came with it; retail or other OS 9 discs will not work.

If you want to install it over Mac OS X 10.3.x and 10.4.x you need the emulator, I guess. I do not remember what I did in older times but, from a moment on, the original 9.1 disk was unsable on newer macs, but any PPC mac, including G 5 generation, included a ‘classic’ installer on one of their accompanying CDs or DVDs. This continued until the last PPC was manufactured, i.e. August 2006.