This page will list feedback from UMax S900 owners regarding S900 specific problems,
solutions and tips. If you have Umax S900 info to share, please contact
OS 9 Upgrade and Twin Turbo Drivers:
I just went through a pain of installing OS 9.1 all over again onto an
S900 with a Crescendo board and Tempo board, CDRW and every single kind
of upgrade you can think of. Everythink went fine (yearly service for my
partner), but I noticed one odd thing. THe display redraw was SLOOOOW.
With loaded drivers.
I wanted to mark a fact about hardware graphic acceleration. When you
install, you usually pop in "Built-In Graphics Accelerator" for generic
But it WON'T WORK on this machine. It did before OS 9 but now it
The windows will be sluggish as hell (as without any driver) with this
extension. And here comes the info.
You have to get the TwinTurbo drivers. There was a guy who was
maintaining a site with them, I downloaded them and I have them, I can
send the installer to someone for public download. [NOTE: - for years
I've had links to a mirror of IXMicro's drivers in the FAQ's
Video cards section. OWC has a mirror of their drivers linked there.-Mike] If I remember, it is
verson 4.0.6. And after you run the installer, you will have three
extensions in your System Folder:Extensions:
TwinTurbo© M8 Upgrade
and a control panel you can throw away because the Monitors panel feels
much more comfortable.
The extensions are called something like that - at least there are
exactly three of them. Well, the trick is that one of these makes your
windows redraw normally, while others are doing a reverse operation -
slowing you down. You must ONLY leave TwinTurbo Acceleration and
everything redraws blazingly fast - just even faster than before and
close to what I see on my dual G4. Just a tip - may be useful to someone.
Overall - a nice machine. Still perfetto for server purposes nowadays.
Maybe I am subjective on the redraw speed, but my perception is usually
Hope this helps someone someday.
Julian "Julik" Tarkhanov
(1998 updates follow)
Q & A with Umax on PCI Slot Usage: Jeff Walther's original mail to umax and a later update:
[His latest mail] [Added 10/28/98]
I thought I'd follow up on the message from Umax tech support that I
forwarded to you. Umax recommended installing two PowerDomains in the top
two slots and two Twin Turbos somewhere in the bottom four slots in my
While fiddling with the configuration over the past couple of weeks I just
had one PowerDomain and one TT in the top two slots. I finally collected
all the hardware I wanted and configured the S900 with two PowerDomains in
the top two slots and two Twin Turbos (4 MB, not the Apple OEM card) in the
bottom two slots. At the same time I added one Atlas II 4 GB to each of
the PowerDomains, leaving the stock 2 GB UW Western Digital drive attached
to one of them. I also added a CDRW to the Fast internal chain with the
regular CD-ROM drive.
When I tried to boot from the same boot disk I had been using, the machine
would load all the CP's and extensions, but freeze (cursor doesn't move,
programmer switch has no effect) before mounting the hard drive volumes on
I tracked the problem down to the Twin Turbo Acceleration extension, but
changing its load order wasn't helping. I have version 4.02 and it's my
understanding that slot preference issues for the TT were fixed with that
Finally, I removed the cards and put one TT and one PowerDomain in the top
two slots. It booted fine like that. The PowerDomain had the Western
Digital boot drive and one of the Atlas drives on it. Then I added the
other cards one at a time booting between each change. It booted fine
everytime. Finally, I found myself back at the configuration that was
troubling me, and it works great. Apparently, it just didn't like having
everything changed at once. And yes, I did try zapping the PRAM when the
problems first cropped up.
Perhaps this will help someone else who changes several aspects of their
configuration simultaneously. It might be a good idea to back up and
change on thing at a time. I've always found that to be a useful
troubleshooting technique. In this case it solved the problem, rather than
helping me to identify it.
[His original Mail follows:]
My Question to Umax:
My question regards PCI cards and which slot to use. I have seen many
discussions which recommend putting various cards in the upper two slots.
I've heard explanations that range from "it won't work otherwise" to
"performance is better".
I have two IxMicro Twin Turbo TT128M4's and two Adaptec PowerDomain
2940UW's. Obviously, all four of them cannot go in the upper two slots.
1) Is there a list of cards that must be installed in the upper two slots
in order to function properly? I didn't see such a list in your support
2) What configuration would you recommend for my S900 and cards? Will it
affect performance to place my video cards or my SCSI cards in the lower
slots? If so, will the performance difference be significant or is it just
a matter of a few percent?
3) Is the whole upper two slots thing overblown? Will pretty much anything
will work in any slot without problems or performance losses?
Thank you for your time and attention,
[UMax Tech Support Reply:]
There are too many cards currently on the market, and being newly released,
for UMAX to test and list them all, basically we look at what type of cards
will benefit from using different slots.
The Power Macintosh 9500 uses two Bandit chips to manage the data flow
between the processor, the PCI slots, and the rest of the I/O circuitry in
the computer. The SuperMac S900 uses one Bandit chip for the top two PCI
slots and remaining I/O circuitry.
The DEC 21052 PCI-PCI bridge chip directly controls the bottom 4 PCI slots
and provides direct PCI-PCI slot communications between all six slots. Data
may travel directly between each of the PCI slots at more consistent and
higher data rates because it does not have to be routed through main memory
and does not have to share the same PCI controller which also manages the
I/O circuitry. In laymans terms, you do not take advantage of the top two
slots, you take advantage of the bottom four slots, because these are the
slots that use the bridge chip to transfer data from slot to slot instead
of having to travel through the logic board to get to the next slot.
You would be taking advantage of this slot-to-slot speed increase when you
are using a configuration which actually sends data from slot to slot.
(Such as two video cards). I tried to access Digital.com to see what the
performance gain percentages were when utilizing the bridge chip but their
site was apparently too busy. If you like, go to:
http://www.digital.com/info/semiconductor/. Do a search for "DEC 21052" and
see if you have better results.
It won't really matter, as you have only one real configuration option,
(SCSI cards - top two slots, video cards - bottom four slots). There are
three factors when installing PCI cards:
1. PCI cards have to be PCI 2.0 compliant to be compatible with the bottom
four slots. Most PCI cards are to this compliance level at this time, and
this isn't usually a problem with any card beyond SCSI accelerator cards.
2. The "real" factor here is that SCSI Controller cards by nature, prefer
to be at the beginning of the PCI bus, and prefer the "Legacy" hardware.
This would make the optimum configuration for your machine to have the SCSI accelerator cards in the top two slots and the two video cards in some
configuration in the bottom four slots, (See below).
3. Lastly, some cards need to be rearranged due to the relationship to the
other cards installed. In other words, you may need to swap the SCSI
accelerator cards in slots A-B, and you may need to place the two video
cards close together, NEAR the SCSI cards, i.e., slots C-D, or close
together and AWAY from the SCSI cards, i.e., slots E-F. And lastly, the
video cards may prefer being apart from each other, and close, or far from
the SCSI cards, i.e., slots C-F or D-F. Anything goes when installing
multiple cards, sometimes with no apparent rhyme or reason.
The only thing to keep in mind is that SCSI cards prefer the top two slots,
and play with the video card configuration if there are any problems
booting the machine. Please let us know if we can be of any further
UMAX Technical Support
OS 8 Install/E100 Termination:
I had a whole lot of problems installing OS8 on my UMAX S900. Would
hang on installing certain extensions. Just found that it was a
termination problem. I had the E100 (Ethernet 100 and ultrawide SCSI PCI
card) installed by the reseller I got it from, however this connects the
internal HD up to that card. The CD-ROM drive is then the only device left
on the standard SCSI-2 internal chain and needs to be terminated. Once I
set the termination and termination power jumpers to on on the CD drive all
problems were solved. If the E100 card is not there, then the internal HD
(which is terminated) will be the last device on the internal SCSI-2 chain
and the CD drive does not need to be terminated. How this saves some other
people some time, as it took me a while to track the problem down. Kudos
to UMAX though as although effectively having a voided warranty and right
to tech support by importing from the US to Japan, they were still more
than helpful with advice on their web entry tech support page.
Licensing Extension Explained:
Mr. Wederfort didn't say which version of the Licensing Extension was
running [that conflicted with Word 98]. Umax support suggests updating to version 2.0.2.
The latest version fixes conflicts with Mac OS 8.0 and some programs.
Not being a seasoned programmer (at least not yet), the best explaination I
was given by a freind who is, is that the extension itself primarily
returns auxilary system software (i.e. gestalt) vendor information by
adding "hooks" into the Finder -which by the way, could concievably
compromise or conflict with the functionality of certain Finder operations
such as printing-
Secondarily, the extension also allows for limited customization of certain
hardware functions such as "Energy Saver" system functions.
For those that are interested the primary Finder elements being acted upon
by the extension are:
gestaltSoftwareVendorApple 'Appl' (System software sold by Apple Computer)
gestaltSoftwareVendorLicensee 'Lcns' (System software sold by licensee)
I have digressed a little here, hence this note is a little longer than I
originally intented, but I hope this helps.
Mike Del Fava
More S900 Info/Tips:
Here's something that might help some S900 owners. I recently had a
problem with Word 98 quitting with a type 1 error whenever I went to
print. I tried disabling destop print momitor and spooler (which somebody
else said worked for them) but it didn't work. After about 20 restarts
disabling various extensions, I finally found the culprit, Mac OS licence
Printing from Word 98 is fixed.
Anybody know why?
The S900 has 6 internal drive bays and a floppy drive. The order (top to
bottom) is 5.25, 5.25, 3.5, 3.5, floppy, 3.5, 3.5. I'll just refer to them in
numerical order starting from the topmost.
A while ago I added another 3.5 hard drive to my S900 and decided to just put
it in one of the upper bays because they seemed easier to get to, so I threw
it in #4. Last week I decided to throw in an old 5.25 cd rom and another 3.5
drive (really just because I had nothing better to do and no where else to put
them). I put the cd in bay #2, and rather then sandwiching 4 drives in a row,
I put the 3.5 drive under the floppy in bay #5. The problem came when
connecting the power cable to both the drive in #5 and the original drive in
#6. In the S900 are 3 power cables, each with 2 connectors on them. The cable
that I was using to power the bottom 2 drives seemed to be just short enough
to be a real pain. It can reach to #6 fine by itself, but when you try to
connect it to both #5 and #6 it becomes quite a challenge, especially because
the drive in #6 is mounted vertically, with the power connector away from you
and only about 4cm from drive #5.
The solution I came up with was to take out a piece of plastic behind the #6
drive that I can only assume is ment to house a fan to blow on hotter drives.
This in itself was a bit of a pain because I couldn't see how it was held on,
but a little bit of careful pulling showed it was simply snapped on in several
places (one of them was quite persistent, and I had to twist it a bit). After
taking this piece off, I was able to gain enough leverage (and a little more
slack) to connect power to both drives without it looking like it was about to
pull apart and fall on the heat sink. I would hope that there would be another
way to get the power cable to reach (especially because some people may use
that fan enclosure), but I can't see one offhand.
Other then this one cable being a cm or two too short, the inside of my S900
is very easy to work with and switching in and out drives is a pleasant
experience. It would be a real shame if this piece of work wasn't supported
for MacOS X. Its a real pleasure to check in at the site a few times a day, I
wish you continued success.
John F. Gilbreth"
ATI VR Graphics Card Slot Tip:
I just bought my s900, and it is a wonderful machine. I had an old ATI
Xclaim VR that I use for video out. At first, I had blank screen
problems, until I
moved it to the upper slot (A). This cured the problems. This is also
noted in UMAX's tech support pages.
More on the PCI-PCI bridge chip:
Umax's tech support page-
http://www.online1.supermac.com/cgi-bin/kbdisplayrecord/KB00218 - addresses
the problem with PCI/PCI bridged environment:
'....There is one issue of which PCI card users should be aware, and that
concerns the PCI-to-PCI bridge chip used in the SuperMac J700, S900, and
S910. This bridge chip, as described within the PCI 2.1 specification
enables faster data transfer from card to card across the PCI bus by
lessening required interactions with the processor and the rest of the
system.... Certain older Mac PCI cards (meaning pre-2.1 spec. boards -mdf),
either due to hardware, firmware, or software factors, are unable to
properly recognize the bridge chip and may not operate correctly in this
This was a concern I had prior to the purchase of my machine, a Newer
accelerated 275 Mhz G3 S900. A little discretion is required when buying an
upgrade card for these machines.
For the record, Umax does produce an execellent piece of hardware. I'm
quite happy with mine so far, I just hope that I'll be able to run OS X on
Mike Del Fava
Umax S900/PCI SCSI Tip: Apparently the PCI-PCI bridge chip used by the Umax S900 (not on other 6 slot Macs) can cause some problems in certain circumstances. Ryan Dumperth sends a story on this and other tips that may be of use to readers:
I've successfully resolved a couple separate acceleration problems recently, and
I thought other folks might benefit from my experience.
When I installed Conley's SoftRAID 2.0 drivers on an Atlas II running on my UMAX
S900's Initio Miles, there were random freezes during writes. I worked with Mark James
at Conley, and we finally solved the problem by moving the SCSI card to PCI slot
1. I came up with this solution by being suspicious of the DEC 21052 PCI bridge chip
that UMAX used to control PCI slots 3-6 (I originally installed the card in slot
4). When I moved the card under the control of Apple's Bandit PCI controller at slot
1, the problem was solved.
More recently, I ran FWB's Hard Disk Toolkit benchtest on the same Atlas, and
found that the read and write acceleration portions of the SoftRAID's drivers were
being disabled mysteriously. After pulling my hair out, I got a hunch that the MkLinux
booter extension which loads immediately at startup was the culprit. After disabling
that extension, my read transactions went up over 400%, from about 800 to 3400. Write
acceleration was even more dramatic, 120 to 4500, over 3700% faster.
These issues may have plagued others, and I thought your page would be the place
to reach them. Thanks for all your hard work.
If you have other Umax specific tips/problems/solutions, please contact