Alternate volume booting

Reader Dick Larson follows up on a recent Mac 911 column. He writes:

In the latest issue, under “Ready for the Worst,” you speak of using one’s FireWire drive. I have the room to do so, but don’t see how to start up the drive without having the Mac on to be able to choose the OS repair software. Can you suggest somewhere to look up how to do this?

Oh, I can just tell you.

When you boot the Mac, hold down (and keep holding) the Option key. When you do, a mauve screen appears that displays icons of all the bootable volumes attached to your Mac. Your FireWire drive will be one of them (assuming, of course, that you’ve installed OS X on that drive). Just click on that drive, click the Right Arrow icon, and the Mac will boot from the FireWire drive.

  
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