Please note that this table uses the convention of capital letters for command or control sequences. However, one doesn't actually press shift unless specifically directed. (E.g., "control-C" means control and lower-case "c")
| Hold down... | Performs this action | When can I let go? | Comments |
|---|---|---|---|
| General | |||
| command-option-P-R | Reset Parameter RAM (P-RAM) | After the initial chime, hold down this key combination and keep holding until you have heard three more chimes. | A useful way to reset a number of settings for a Mac that is behaving strangely. Resets AppleTalk, Volume, Mouse Acceleration, and a few others. Often a simple 'miracle worker'. |
| Hold down mouse button | Eject removeable media | Hold until desired media ejects. | Convenient way to eject floppies, Zips, or CDs at boot time. |
| C | Boot from compact disc (internal only) | Hold until background or splash screen clearly shows that you have booted from CD, not internal disk. | Allows one to boot from CD without having to select it first in Startup Disk control panel/System Preference. |
| command-control-power key | Reboot from keyboard | Hold until you hear reboot chime. | When machine is frozen, this allows you to reboot from the keyboard, which is analogous to hitting the left-triangle button on the Mac box. No longer works on new USB "Apple Pro" keyboards which lack a power key. |
| New World Macs | |||
| option | Select Boot device or partition | Hold until circular arrow and right-arrow buttons appear. | When wristwatch goes away, click on the device from which you
wish to boot and then click the right-arrow. This only works on New
World Macs (iMac and later). I have seen problems with B&W G3s which
won't do this. (It's all OpenFirmware version-dependent.) This is a major advantage to having OS 9 and OS X on separate partitions, because one can select one or the other at boot-up time. |
| command-option-O-F | Boot into OpenFirmware | Hold until small black letters on white background appear. | There are`a variety of commands you can run here (well beyond the scope of this document). Common ones include "mac-boot" and "shut-down". Only works on New World machines. |
| T | Firewire Target Disk Mode | Hold until large Firewire icon appears on PowerBook screen. | Turn off PowerBook, connect it via Firewire to another Mac, and then press T as you boot up. This mode allows the PowerBook's hard disk to appear as a drive on someone else's Mac. (This is an update of the SCSI Disk mode for older PowerBooks.) |
| OS X only | |||
| command-V | Boot OS X with (V)erbose settings. | Hold until until black on white letters appear. | "Console" booting will give far more information about boot sequence. (More like Linux than the graphical OS X normal boot display.) |
| command-S | Boot OS X in single-user mode | Useful for certain diagnostics and repairs of operating system. You don't need this simply to reset the root password. (Boot from the OS X installer CD for that and choose Reset Password from the Installer menu.) | |
| OS 9 and before (not OS X) | |||
| Shift | Boot without Extensions | Simplified (and quick) boot procedure, usually used for debugging. | Hold until "Extensions off" message appears. |
| Spacebar | Bring up Extensions Manager prior to boot | Hold until Extensions Manager appears. | Select or deselect control panels and extensions as needed. Then close the window to continue to boot cycle. This is often more useful than the all-or-nothing approach of holding down "shift". |
| delete-option-commmand-shift (mnemonic: D-O-C-S) | Boot from non-internal SCSI disk | Hold until you can confirm that desired boot is happening from desired device. | (Depracated, with SCSI's demise on Macs) This technique allowed you to bypass an internal disk and boot from an external device, such as a Zip drive or another hard drive. (Holding down "C" is easier and more reliable for CDs.) One could also hold down a fifth key to specify the SCSI address (e.g., D-O-C-S-4). |