On Thu, 5 Oct 2000, Michael Wolfson wrote:

> OK, let me see if I've got this right.  There are two motherboard revisions:
> Rev 1	OF 2.0f1	Rage II+
> Rev 2	OF 2.4		Rage Pro

	Yes
 
> The ROM is located between the Personality card and the SDRAM banks.
> There are three ROM revisions:

	Correct

> Rev A	$77D.40F2	1997
> Rev B	?
> Rev C	$77D.45F1	1998

	No, Rev B is $77D.45F1. I've heard of the Rev C ROM, but OWC
didn't have it listed in their catalog. I saw mention of it in the Apple
Tech Support Forum, but no one knew what the difference between Rev B and
Rev C was.

> Any ROM will boot either motherboard, but some functionality may be missing.

	AFAIK

> The OF version reported depends on the motherboard, not the ROM.

	No, the OFW is on the ROM itself from what I understand. If I put
a Rev 2 G3's ROM in my Rev 1 G3, it should work the same as it does in the
Rev. 2 machine and report OFW 2.4 It's entirely possible that the ROM in
the Rev 2 G3's is the Rev C ROM.

> Rev A ROM shipped with Rev 1 motherboard, Rev B ROM shipped with Rev 2
> motherboard.  Was Rev C shipped with later Rev 2 motherboards, or only
> after they stopped shipping Beige G3s?

	No, Rev B has apparently been offered as a fix to the Rev A ROM in
Rev 1 G3's. However, since floppy booting still works, it might prove
attractive to Rev. 2 owners as well. I have also just confirmed that
booting from SCSI on the Rev B ROM works regardless of using the System
Disk patches or not. Again, I can't speak about the Rev C ROM because I
don't know anyone who has one.

> Rev A	supports only Rage II+, only master IDE drives,
> 	OF supports floppy, long TFTP timeouts for netboot (up to 15 minutes!)
> 	MUST run System Disk to use IDE or SCSI drives

	Let's clarify those statements further: MacOS only supports Master
IDE, OFW can only boot from Master devices. But, once booted NetBSD can
use both master/slave IDE/ATAPI flawlessly. I've been told the TFTP
timeouts are cause of the ROM not being able to retain the MAC address of
the host or itself. Though I haven't tried it, I've been told that adding
a static ARP entry on the host machine should fix it. I will also add that
the ofwboot.xcf that is shipped on the ftp site doesn't work with the load
address of 0x6c000. It needs to be compiled at 600000. At this time I
don't have a working compiler installed to test this. I can't say if it
supports just Rage II+ or not. It *should* work with either one. OFW
v.2.0f1

> Rev B	supports only Rage Pro, master and slave IDE drives,
> 	OF doesn't support floppy,
> 	MUST run System Disk to use IDE or SCSI drives

No, it should support both Rage II+ and Pro. Master/Slave IDE is fixed
in MacOS with Rev 1 machines. I don't *think* you can boot from slave IDE
drives in OFW still, but I haven't had time to try it. OFW DOES support
floppy on this ROM, as it does with with Rev A in Rev 1 machines. Fixes
TFTP booting, has the added bonus of automagically selecting an add in
video card and use it without user interaction, fixes SCSI
booting. i.e. it boots SCSI without the System Disk patches (even works
better without them it seems) I'm still trying to figure out why I can't
boot IDE, I did it once and then it stopped working. It should also be
noted that you probably will want to hit the Reset button on the
motherboard after installing this upgrade from Rev A ROM. The OFW is
v 2.0f1. Supposibly "adds increased compatibility with ZIF CPU upgrades"
ofwboot.xcf at 0x6c000 still freezes the machine when I netboot it, need
more time.

> Rev C	supports both Rage II+ and Pro, master and slave IDE drives,
> 	OF floppy support unknown, auto-detects and uses PCI video cards,
> 	"fixes" problems with G3 ZIF upgrades,
> 	Running System Disk seems to cause problems

	Mentioned about this earlier. 
 
> Have I got it right?  What's the ROM version of Rev B?  Is there any way to
> tell which version ROM is present *without* the use of Apple System
> Profiler (which requires MacOS) or by turning it on and testing to see
> which devices work properly?  That is, are there any physical differences
> (labels) or OF commands that will tell them apart?

	I haven't had enough free time to figure that out. Undoubtably
there is. Typing .properties as soon as you enter OFW should give some
kind of hexadecimal version string. Maybe this weekend.

> Thanks,
>   -- MW
> 
> http://www.macsales.com     search for OWC part number ZIFROMB, currently US$35
> http://www.mactoolbox.com/bb/rom.html