various keys that do various things when a mac is starting up. ..

| **what?** | **what?** | 
| ⌘(splat/apple)&s | single user mode |
| t | firewire target disk mode | 
| c | startup from cd |
| shift | safeboot/ no extensions |
| alt | open firmware boot | 
| ⌘(splat/apple),alt,o&f | [[Open Firmware]] cli |
| ⌘(splat/apple),alt(option),p&r | "zap the pRAM!!!" |
| ⌘(splat/apple)&v | verbose startup |

  * restetting the SMC -> https://support.apple.com/kb/HT3964