Apple Start-Up Key Combinations
Written by Peter A. Haigh   

From time to time even a Mac needs a little troubleshooting. When the computer fails to start normally, there are several keyboard combinations that can help by starting the computer in special modes. Here is a brief run-down of the more commonly-used combinations. If you do not know what these start-up options do, DON'T USE THEM! You can SERIOUSLY further the downward-spiral of your computer!!! 


 Description Key Combination
Bypass startup drive and boot from external (or CD) CMD-OPT-SHIFT-DELETE 
Boot from CD (Most late model Apples)  C 
Force the internal hard drive to be the boot drive D 
Boot from a specific SCSI ID #.(#=SCSI ID number) CMD-OPT-SHIFT-DELETE-# 
Boot into open Firmware CMD-OPT-O-F 
Clear NV RAM. Similar to reset-all in open Firmware CMD-OPT-N-V 
Disable Extensions SHIFT 
Rebuild Desktop CMD-OPT 
Close finder windows.(hold just before finder starts) OPT 
Boot with Virtual Memory off CMD 
Trigger extension manager at boot-up SPACE 
Force Quadra av machines to use TV as a monitor CMD-OPT-T-V 
Boot from ROM (Mac Classic only) CMD-OPT-X-O 
Force PowerBooks to reset the screen R 
Force an AV monitor to be recognized as one CMD-OPT-A-V 
Eject Boot Floppy  Hold Down Mouse Button 
Select volume to start from OPT 
Start in Firewire target drive mode T 
Startup in OSX if OS9 and OXS in boot partition X or CMD-X 
Attempt to boot from network server (Hold until Mac Logo appears) N
Hold down until the 2nd chime, will boot into 9? CMD-OPT 
OSX: Watch the status of the system load CMD-V 
OSX: Enter single-user mode (shell-level mode) CMD-S