Just by holding down a particular set of keys when you startup the Mac, you can change how it boots. Be sure to press the key combination before the gray Apple appears (after the chime is best) , and you can release them after the Apple appears on-screen. Here are some shortcuts:
- Hold down 'C' - Startup from a CD or DVD
- Hold down 'T' - Startup your Mac into Target Disk Mode. This mode makes your Mac boot as a bootable Firewire drive.
- Hold down 'X' - Forces your Mac to use OS X, just in case you have your Mac setup to boot into OS 9.
- Hold down 'Command V' - Starts up in verbose mode, and shows you whats going on while your Mac is starting.
- Hold down 'Shift' - Boots your Mac into Safe Boot mode (great for troubleshooting).
- Hold down 'Mouse button' - CD or DVD stuck? This will eject a disc from your drive.
- Hold down 'Option' - Choose what disk to boot from. Users of BootCamp use this all of the time.