The firmware console on Alphas running either VMS or Tru64. The SRM console provides all sorts of useful features such as allowing you to list the connected devices (show device), boot off a device other than the standard boot device (boot devicename) and reboot the machine (init). Typing show will list the state of the console environment variables - you can alter them by typing set variable value. You can also write stuff into random chunks of memory if that's the sort of thing you enjoy doing, which is handy for doing things like altering the uid that your shell is running as.