[HAL9000]

The BIOS is where the bootstrap code is, and unless there's a bank of register switches hiding somewhere on the Mac for hand loading the bootstrap code (like I had to do on a DEC PDP-4 a long time ago), there's BIOS there somewher

The term "BIOS" is usually associated with x86 computers (and CP/M computers previously). In a generic sense, punch cards and microcode could be called a BIOS too.

And things must have changed tremendously over the years. Apple used to guard their BIOS code, as well as their architecture specifics very carefully, which is why there were only a very few licensed clones of Apple systems over the years.

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

And I also remember when some of the Apple BIOS code was released on the Internet some years ago. Apple went APE!

There were several instances involving firmware, not BIOS code. Some hackers disassembled the firmware and distributed annotated listings, and some system cloners like Franklin simply copied binary the firmware.

[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