Setting Classic Preferences in Mac OS X

When you install Mac OS X 10.1 on your Mac, you actually get two operating systems. Mac OS X, of course, runs your machine, but Mac OS 9.2.1 — the Mac OS version just before Mac OS X — is available, too, if you need it.

Mac OS 9.2.1, which is called Classic when running under Mac OS X, actually runs inside an operating system (OS) emulator — software that does most, but not all, of what an operating system does by pretending to be one. When you launch an older application, it's as if you've booted a computer within your computer; that is, Classic first emulates the startup process, loading all the stuff that it needs to mimic Mac OS 9.2.1 and run the application.

Classic is an application, just like AppleWorks, Internet Explorer, or TextEdit. With the Classic application running, you can use Mac OS 9.2.1's Apple menu and you can open Mac OS 9.2.1 applications. You also have access (by switching to another window) to your Mac OS X Desktop and applications. Finally, you can switch to another program (from a Classic program) by choosing it from the Application menu, on the far right of the Mac OS 9.2.1 (Classic) toolbar.

If you have multiple hard drives or partitions with Mac OS 9.2.1 installed on them, you can choose which one to use as the operating system for the Classic environment. You make that choice in the Classic pane of System Preferences. Just select the drive or partition (this example is labeled Number 9 in Figure 1), and the next time that you launch Classic, it uses that volume's copy of Mac OS 9.2.1. Volumes that don't include Mac OS 9.2.1 appear dimmed in the preferences window.

By selecting the Start up Classic on Login to This Computer check box, you tell Mac OS X to do just that. The advantage is that you won't have to wait a minute or two for Classic to launch the first time that you launch a Classic application. The disadvantage is that your Mac takes an extra a minute or two longer to boot, and Classic continues to use RAM and other system resources even if you're not working in a classic application.

Note the three buttons at the bottom of the System Preferences Classic pane's Start/Stop tab (the last two are used mostly when the Classic environment crashes, freezes, or otherwise acts improperly):

• Start: Launches Classic without first launching a Classic program. (If Classic is already running, this button reads Stop.)

• Restart: Restarts Classic (big surprise), which is like rebooting OS 9.2.1 without having to reboot OS X.

Force Quit: Forces the Classic environment to quit, even if it's crashed or frozen