Step 1: Choose System Preferences from the Apple menu

Step 2: Choose Startup Disk from the View menu. The Startup Disk pane appears, and the current startup System Folder is highlighted.

Step 3: Look at the lock button
If the lock button appears closed, click the lock to make changes. Enter an Admin user name and password, then click OK.

Step 4: Click the System Folder icon of Mac OS 9 volume you wish to start up fromWhen many choice are available, move the slider bar to see additional choices. A gold "9" badge appears on the icon of a Mac OS 9 System Folder if it is located on the same volume as Mac OS X.

Step 5: For Mac OS X 10.1 and later, click the Restart button. A confirmation dialog appears (Figure 5). Click Save and Restart.

Note: In versions of Mac OS X prior to 10.1, the restart button does not appear here. Instead, choose Restart from the Apple menu.