Where’s my Mac BIOS? (How to get into OpenFirmware Easily)

A lot of people these days appear to be under the impression that Macs have a BIOS, which is unfortunate because they actually have something much better – Macs have OpenFirmware. This is true for G4 Mac Minis, PowerBooks, iBooks, iMacs, eMacs, and Dual G5s… I could go on and on.
I got most of this info from experience and the Apple Developper Connection – if you’re not a member yet, sign up, it’s free.

You can get into OpenFirmware using this key sequence:

CMD-OPT-O-F

In detail, this means using two hands, holding “command”, “option” and “f” on the left and “o” with your right hand. Do this while booting your computer and you well hear two chimes. At the end of the chimes you will be greeted with an

On my G4 Mac Mini, for example, I can hold down the power button for roughly 10 seconds and I will hear the chimes – this should work for iMacs as well.

The OpenFirmware prompt that looks like this:

ok

0>

Congratulations, you’ve accessed your “BIOS” you switcher!

Now that we’ve passed this glorious milestone, we have some work to do. After all you came here for a reason right? (and not just to click on the ads, wink-wink nudge-nudge)

Some useful commands that save me time and time again, and enable reparation of the G4 Mac Mini:

Boot your Apple computer using the default boot device:

0 > mac-boot

Boot your Mac using the inserted CDROM at the yaboot directory for linux CDs:

0 > boot cd:,\install\yaboot

To eject a CDROM from your Mac:

0 > eject cd

If you have any other OpenFirmware tips to share, feel free to comment!

Access Your Computer’s BIOS

UPDATE – Many people have asked me to write an article about accessing a Macintosh BIOS, so here it is!

I helped a friend out today who wanted to reinstall Windows on his Dell laptop. When he inserted the CD into the drive and rebooted, the computer still booted into Windows and would not boot from the CDROM drive for him. Having seen this many times before, I told him to change the boot order so that he could boot from the Windows installation CD. Since he was unsure of how to do this, I have a feeling that most people would be stuck were they in the same situation. Here are the most common keystrokes that will get you into your BIOS. Once you are there, change the “boot order” or “boot sequence”, so that the CDROM is the first item. Once that has completed, save the changes and exit. Presto! you can now start the installation and proceed with glee.

Phoenix BIOS (older)

  • Ctrl+Alt+Esc
  • Ctrl+Alt+F1
  • Ctrl+Alt+S
  • Ctrl+Alt+Enter
  • Ctrl+Alt+F11
  • Ctrl+Alt+Ins

Award BIOS

  • Ctrl+Alt+Esc
  • Esc
  • Del

AMI BIOS (most common)

  • Del

IBM BIOS

  • Ctrl+Alt+Ins F1

Compaq BIOS

  • F10

Dell BIOS

  • F2