Comparable BIOS Component in Mac?


macrumors newbie
Original poster
Nov 6, 2004
Hey everyone,

I have a quite banal question concerning the inside of a Mac and hope you can help me out. Although I am an experienced Mac user for many years myself I couldn't answer this question when asked. Is there a comparable device inside a Mac that acts as the BIOS in a PC? If not, what is the reason the Mac doesn't need one? (I have been told before that such a thing is not needed.)

Thanks for any answer that will help me not to embarass myself again :p



macrumors G5
Jun 6, 2003
Solon, OH
The closest equivalent to the PC BIOS in Macs is Open Firmware. You can access it from a "New World" Mac by holding down Command+Option+O+F at startup. If it worked, you'll see an odd-looking command prompt like screen that doesn't look at all like Terminal. In here, you can make low-level hardware changes, such as resetting the NVRAM (reset-nvram), resetting everything (reset-all), continuing normal startup (mac-boot) or rebooting the Mac (reboot). The name in parentheses is the command you type at the Open Firmware prompt to achieve the described effect.

Sun Baked

macrumors G5
May 19, 2002
57 -- list of the mirrors

There is a manual on programming in OF, you can do some stuff that is quite interesting while in there.

Somewhere around is the .pdf manual to buy, could find where it is. Not free though.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.