Macs don't have a BIOS. They have something called Open Firmware instead. So the BIOS password is called Open Firmware password. You boot into Open Firmware by pressing the command (=apple), option, O and F keys simultaneously during system boot. To set the password type
password To enable the protection type
setenv security-mode full An then reboot by typing
reset-all Apart from the full security mode you can also set "none" (= don't ask password during boot) and "command" (=gives you only limited access to Open Firmware without the password. The Open Firmeware password can be removed by changing the amount of RAM and three times zapping the PRAM. More detailed information is available.