OWC has been shipping, and probably still is,
Rev. C ROM modules for beige G3 Macs of the Rev. A series.
These shipped with a RageII+ graphics chip and with 2 IDE busses, both
capable of accepting only one drive each. Rev. B and later shipped with
RagePro chips and IDE busses that were master/slave capable, ie would
accept 2 devices.
The ROM chip from
OWC now adds this feature to the IDE busses and also allows to run their
OEM Zif CPU upgrades with copper G3s. I bought such a ROM module for a
whopping 82$ including 33$ FedEx shipping, which I really didn't need,
but had no other choice. I conducted a few tests with the old and new
ROM and here is what I found:
Here first some info
on the different modules and how to install it.
Installation is pretty straight forward. Open up your Mac, following all
the grounding etc procedures, locate the old ROM module in the ROM slot
and remove it. This is admittably a fairly tricky thing to do, since that
bastard fits really tightly. You are also not allowed to rock back and
forth, since the slot is designed to "operate" only in the vertical
direction, and you surely don't want the connector to break off your mainboard.
But there's an easy and efficient trick to speed up the removal a lot.
Get yourself 2 wires (isolated) of about 7" lenght or so and bend
them into a small J. You'll find that the ROM modules feature 2 holes
on each side, were you can fiddle those hooks in. Then pull the shorter
end of the J gently through the hole until both ends are on the same height
again, forming an U with the ROM module in between. Do this on both sides.
Then twist both ends of each U together, slip you index in the latch and
pull symetrically on both sides.
The ROM will come out with a click.
To install the new ROM, all you have to do is put it vertically into the
connector and press down firmy on both sides until you notice a soft click
when the ROM module snaps in.
Then close you Mac back up, reconnect the power and start it up.
You'll also want to
make sure you really got a Rev. C module, in case you didn't get it from
The Rev. A module has 2 ROM chips dating back to 1997, while the Rev.
C module has 2 chips dating back to 1998. Also in the Apple System Profiler
you can look up the ROM revision:
A has revision number "$77D.40F2"
C has revision number "$77D.45F1"
old beige G3 has been running for almost 2.5 years now, all very stably
(except in Quake 3, of course) and rarely needing any service, that's
also why my HD is in a pretty messy state, of course hitting performance
quite a bit, but I'm too lazy to defragment it etc. All tests were conducted
under the same conditions, after a restart.
System Info 4.5
There was no effect on graphics
or CPU/FPU performance, although, the new ROM resets my screen once at
startup, where the old one didn't, but as it seems, startup times are
a bit faster and, oh horror, disk performance seems to drop quite a bit
in MacBench's Publishing Disk test. I consider the other differences a
pure accident, also Quake 3 never reports the same FPS twice.
Now why did I buy that thing anyway? I wanted master/slave
connected a 2 device IDE cable to my HD IDE bus and attached my original
WDC Caviar 36400 as amster and an old IBM DALA 3540 as slave (you can
look up your jumper specs on IBM's
After a reboot and
updating of the drivers on the DALA, the drive mounted like a champ, no
problems whatsoever. However, I had planned to install the drive on top
of my Floppy drive, the same way I had done so with an IBM DNES SCSI drive
on to of a Zip (see here), and
found that the DALA is too fat to go in between that space. The space
between case and floppy is only about 1.8-2 cm high and a normal HD is
It could be done with some grinding on the drive sledge etc, but that
really is too much effort, especially because that will also dealign the
Floppy cover slot, forcing you to leave it open (and really ugly).
However there are extra flat drives who are only about 1cm high or so,
and these would fit in just fine.
I'm yet thinking of options, and I'll let you know if I find any.
If you have some
space left in your case and want to add one or more IDE/ATA drives this
upgrade is a must. But if you have added SCSI drives before and don't
have any space left, stick to your SCSI drives and save the 82$ for an
UW/SCSI PCI card or so. The performance drop with the Rev. C module may
have been a twist of fate, and in case it is not, most of you probably
will never notice.
OWC now also ships Rev. B ROM modules
which offer the same functionality. The price has also been reduced to
35$. I have not tested one of these yet, but I think there is no significant
Text: © by Bensch Blaser, Jul. 2000, all trademarks
are property of their respective owners.