[Paridel]

Err, BIOS is an acronym for "Basic Input/Output System"

I believe it has always referred to any on chip code that performs basic initialization and allows the machine to bootstrap itself. Apple's is known as "Open Firmware". It does the same stuff as a PC's BIOS. I think the main reason that it is not referred to as a BIOS is that unlike PCs people generally leave it along, although it is pretty easy to access with the right key combination.

In a generic sense, punch cards and microcode could be called a BIOS too.

Um, no, not really.

Mac OS X is built on top of Darwin, an open source Unix.

Factually correct, but this has nothing to do with the discussion at hand. You man remember (or maybe not?) booting Linux or NetBSD on older macs? Originally it was not possibly to boot directly into those operating systems... you first had to boot into MacOS and then bootstrap the machine from MacOS using a Control Panel.

-paridel

[HAL9000]

Err, BIOS is an acronym for "Basic Input/Output System"

Open Firmware is not a "Basic Input/Output System". You can't call BIOS on a Mac - unless you're running an x86 emulator like Microsoft VirtualPC.