Installing Mac OS 9.x
In order to use Mac OS 9.x and the Classic environment, you must install it. How you do this depends on how Mac OS X was installed on your computer:
If you updated your computer from Mac OS 9.2 or later to Mac OS X and did not initialize your hard disk as part of the installation process, Mac OS 9.x is still installed on your computer, so you probably won’t need to do a thing.
If you updated your computer from Mac OS 9.0 or earlier to Mac OS X, you’ll need to update the existing version of Mac OS to 9.1 or later.
If you erased or initialized your hard disk when you installed or upgraded to Mac OS X, then only Mac OS X is installed. You’ll need to install Mac OS 9.2 or later.
If you purchased a new computer with both Mac OS ...
Get Mac OS X 10.4 Tiger: Visual QuickStart Guide now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.