Hey, I recently got a Beige G3 All-in-One from a friend and I'm interested in figuring out what ROMs it has (A,B, or C). How do I do it?
Two ways to identify the version are: 1) Run Apple System Profiler, look at the ROM version listed and cross compare that to the list at LEM; 2) pop the top, look for the graphics chip; the three rev levels used a RageII, RagePro, and RagePro+DVD chip.
One note about using apple system profiler. I used it once in OS X and it gave me some odd rom revision. I figured out that you have to actually use the apple system profiler in os 9 (or lower) to get an actual reading of what your rom revision is. I have a rev 2 rom in my beige, but when I run apple system profiler in os x, it told me that my rom was the same one that is in the B/W macs.
The video chip isn't reliable, though, unless you're 100% certain that it is the original ROM chip.
I guess one other method is to pop in a slave IDE drive and see if the machine recognizes it. If it doesn't, then its got a Rev A ROM.
The previous owner of my Beige put a Rev.A ROM into the Rev.C board that was in it. His ROM died supposedly and he got a new one off of e-bay. He didn't know any better, so he put the Rev.A in there. It works fine for my purposes (I don't have a slave drive) but annoying nonetheless.
OS X doesn't work with the on-board ROM like OS 9 does. Naturally, when you boot OS X, it uses the ROM-in-RAM ROM image on the disk instead. That ROM version will be the same as virtually any other machine running OS X.
... or you could read the part number on the ROM SIMM.
If it is 820-0954-01 (or is it *-1?), then it's a Rev A ROM.
-A or other endings indicate Rev B or better. Supposedly.
My 820-0954-A reads as $77D.45F2 (rev C) in ASP, but some websites say that 820-0954-A should be a rev A rom ($77D.40F2) and some say it should be $77D.45F1 (rev B).
There's a lot of FUD out there about motheboard/ROM revisions anyway. Supposedly, you need a rev C board and rev C ROM to support 256MB RAM modules. Bollucks. My Rev A board w/ Rev A ROM works fine with 256MB RAM DIMMs. As does my Rev A board, rev C ROM and rev B board, rev C ROM. (I haven't tried the other combinations.)
As far as I can tell, the only REAL rom/board limitations are that rev A ROMs don't support 2 devices (master/slave) on the IDE bus. The Rev A board has a cruddy ATI Rage II+DVD and doesn't support DVD playback or OpenGL. The Rev C board does have DVD playback support, supposedly. Rev B/C ROMs support master/slave. Rev B/C board support OpenGL.