Here is a list of some handy keys to hold down while starting up your Mac in OS X.
Press keys immediately after you hear the startup tone…
- C Boot from a CD or DVD (such as the Mac OS X Install disc)
- Option Select a volume to boot from
- X Force system to boot into OS X
- N Attempt to start up from a compatible network server (NetBoot)
- Option-N Start from a NetBoot server using the default boot image
- D A Start Apple Hardware Test (AHT)
- Option-C-P-R-B Reset non-volatile RAM (NVRAM)
- Shift Start up in Safe Boot mode and temporarily disable login items
- C-V Start up in Verbose mode
- C-S Start up in Single-User mode
- T Start up in FireWire Target Disk mode
- Eject, F12, or mouse button Eject any removable media, such as a CD or DVD