How to Get to the BIOS in OS X

By Thomas King

Basic Input/Output System (BIOS) is an interface found on PC computers. Mac OS X has its own version of BIOS called OpenFirmware or Extensible Firmware Interface. Just like BIOS on a PC, OpenFirmware can be used to communicate instructions to your operating system. For example, you can eject a CD, view a directory, change your boot order, and set up password protection.

Step 1

Restart your computer.

Step 2

Hold down the "Command," "Option," "F" and "O" keys simultaneously while your computer is booting up.

Step 3

Type your username and password if prompted. You will see the following text on your computer screen: "ok 0>"This indicates that you have entered OpenFirmware (BIOS).

Tips & Warnings

  • If you want to set up a password to prevent unauthorized users from entering OpenFirmware, type "password" (without the quotation marks) and press "Enter." You will be prompted to choose a password. Type the password you want to use and press "Enter." Then, type "setenv security -mode full" (without the quotation marks). Press "Enter," type "reset-all" (without the quotation marks) and press "Enter."