| Keystroke | Description |
|---|---|
| Press C during startup | Start up from a bootable CD, DVD, or USB thumb drive (such as OS X install media). |
| Press D during startup | Start up in Apple Hardware Test (AHT). |
| Press Option-Command-P-R until you hear startup sound a second time. | Reset NVRAM |
| Press Option during startup | Start up in Startup Manager, where you can select an OS X volume or network volume to start from. |
| Press Eject, F12, or hold the mouse or trackpad button | Ejects any removable media, such as an optical disc. |
| Press N during startup | Attempt to start up from a compatible network server (NetBoot). |
| Press T during startup | Start up in Target Disk Mode. |
| Press Shift during startup | Start up in Safe Boot mode and temporarily disable login items. |
| Press Command-V during startup | Start up in Verbose mode. |
| Press Command-S during startup | Start up in Single-User mode. |
| Press Option-N during startup | Start from a NetBoot server using the default boot image. |
| Press Command-R during startup | Start from the OS X Recovery System |