OS 9.2.2 on a G5?

What is the newest Mac and OSX operating system that will allow me to run OS 9 in Classic mode?

Any PPC Mac running Tiger or lower version of OS X. Classic does not work with any Intel mac.

Will it work on any G5, so long as I run Tiger as the principal OS?

Should do.

Will Classic work with any version of OSX newer than Tiger?

No.

John61254 wrote:

I want to be able to access some old OS 9 files.

Are you talking about files or applications? If files, what sort?

It may be that some files created in OS9 can be opened in OSX by later/other applications.

If you don't have OS 9 on the install disc that came with the G5, 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 😉