Essential classic Mac boot key combos

Press this together with Power button

• Cmd-Option-P-R Reset PRAM.
• Cmd-Option-Shift-Delete-(#) Boot from a SCSI device on the SCSI bus other than the disk selected in the Startup Disk control panel. The Optionional number allows for booting from a specific SCSI ID.
• R Force PowerBook to reset screen.
• C Boot from Apple-brand CD-ROM drive. Works with a few third-party drives too. For drives that can't boot using the C key, try Cmd-Option-Shift-delete as explained above.
• Hold mouse button Eject floppy and optical drive.

Press this after startup chime plays

• Command Boot with virtual memory off (System 7 - Mac OS 9.x only).
• Shift Boot with Extensions, Control Panels, and Startup Items disabled (including VM, if on).
• Space Open Extensions Manager (System 7.5.x and higher only) on boot.
• others Check documentation for third-party extensions and control panels; there are often keys to disable these individually.

Press this before Finder starts, after Mac OS logo dissapears

• Cmd-Option Rebuild the desktop file.
• Shift Disable Startup Items only.
• Option Start Finder with no open windows.

The following are some other useful shortcuts/undocumented combos

• Cmd-Option while opening Memory control panel: allow startup RAM tests to be turned off (Mac OS 8.5 - 9.x only).
• Cmd-Power Enter NMI, or Macsbug (if installed).
• Cmd-Option while opening Chooser: rebuild Chooser's cache.

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