Technical specifications


Model:CDC Cyber-910B-482 aka. Silicon Graphics Personal Iris 4D/30

CPU:MIPS R3000, 30Mhz (IP12)
RAM:32 Mb

IO system:Single SCSI channel
Storage:Seagate ST41200N, 1 Gb

Graphics: Entry graphics with BP4 and ZB3 upgrades
Console:101-key US keyboard with PC-AT layout
3 button mouse
20" Hitachi CM2086A3SG monitor
This is a fixed-frequncy sync-on-green monitor capable of displaying 1280x1024 at 60hz.
It has 3xBNC connectors

Sound:optional, not installed

Network:10mbit, AUI connector only

Case:Indigo blue Tower

OS (current):Irix 5.3

Wanted:8 Mb SIMMs in quantities of 4 at a time
Magnum sound-option
GT2 piggyback cardset for TG upgrade
5.25" half-height drive-sled for CDROM or a drive-sled for a second 5.25" full-height harddrive


This machine is one of the rebadged Personal Iris machines sold by Control Data Corporation as the CDC-9xx series workstations.

It's one of the models with the BP4 24-bit color plane upgrade and also the ZB3 24-bit Z-buffer upgrade.

The gfx boardset is of the GR1.2/1.5 variant, identified by the extra DB15 composite output. This means you can hook up and ordinary PC monitor as long as it's capable of 1280x1024x60hz, I tested this with my 15" ADI Microscan 4v and it works fine.
Being a GR1.2/1.5 also means it should be possible to turn this into a TG board by replacing the LSI graphics chip with a GT2 piggyback cardset.

The last version of Irix that will run on this machine is Irix 5.3 since R3000 support was dropped from Irix 6.x.

The mouse and keyboard uses PS/2 style 6 pin mini-din connectors. The mouse is connected through the keyboard. Though the connectors look like those of a PS/2 they are not compatible, the SGI uses a different protocol.

This machine has all ram-slots used since the 32 Mb is fitted as 16x2 Mb.
The SIMMs used are the same ones as those for the 4D/35 and the R3000 based Indigos. These SIMMs are proprietary to SGI.

The Seagate ST41200N is a 5.25" full-height drive of the WREN7 family (Irix 5.3 fx sees it as an Imprimis model :)) and it weighs a ton :)

Within the last couple of months I'm afraid that the Irix 4.0.5 installation has been damaged. Atleast there are now some severe problems with the display. For an example of the problem look here. As you can see in the picture the background is red and there is a big hole where the login-box was. What you also can see is that moving the root-menu around will "erase" the red color.
I think it's software and not hardware because xdpyinfo segfaults, so does xv when I try to put an image in the root-window. It didn't do this some months ago when I last used the machine. I also ran the diagnostics from the prom, it gave no errors. Besides the problem doesn't happen until the X-server starts, until then all is well.

Woohoo! I finally got a CD-drive that would let me install Irix 5.3 on this machine. To avoid ruining my existing 4.0.5 installation I pulled out the internal HD and used an external DEC RZ56 (660 MB) to install on instead. This worked just fine and after booting Irix 5.3, it turns out that the gfx is indeed not faulty since there are no problems at all after starting X now.


The ultimate source for information on the old 4D series SGI machines is This Old SGI by A.J. Corda


Last updated 04-05-2004 by Tom G. Christensen (