Personal Iris



Personal Iris front with 4D/35 logo.

The Personal Iris was introduced in 1988 as low end workstation to the IRIS 4D series based on MIPS RISC microprocessors. The previous installment of the IRIS 4D series were the Professional Iris systems, the higher end models are the PowerSeries computers.

A model name consists of "4D/" and a code designating the CPU and graphics type (example: "4D/25TG" is a 20 MHz MIPS R3000 machine with Super Turbo graphics).

The following ASCII table is taken from an old marketing brochure and extended with some data found on the web.

          4d/20     4d/25      4d/30     4d/35
MIPS        10        16        27        33
MFLOPS      .9        1.6        4.7       6.0
SPEC89      9?        14        25.4      31.1
SPECint92   -         14        -         -
SPECfp92    -         13        -         -


Model CPU board CPU Chassis
4D/20 IP6 MIPS R2000 12.5 MHz Tower
4D/25 IP10 MIPS R3000 20 MHz Tower
4D/30 IP14 MIPS R3000 30 MHz Tower
4D/35 IP12 MIPS R3000 36 MHz Tower

Between the 4D/2x and the 4D/3x systems are major differences. The latter one uses a totally different system board which besides faster processors includes a newly designed memory interface that allows much higher bandwidth and a larger amount of main memory. The system bus of the newer boards is clocked at 30 MHz instead of 10 MHz.


1988, October
Personal Iris systems (4D/20) introduced
1991, April
4D/35 announced


4D/20 and 4D/25

The following is an overview of the 4D/20 and 4D/25 CPU boards.

CPU Board Processor Clockspeed Cache (d/i) Cache (2nd) Floating Point
IP6 R2000 12.5 MHz 8kb / 16kb none R2010 onboard
IP10 (sw: IP6) R3000 20 MHz 32kb / 64kb none R3010 onboard

Late revisions of the IP6 CPU board are equipped with the R3000 CPU clocked at 12.5 MHz.

The IP6 and IP10 system board have status LEDs that are visible from the back of the Emodule:

  *ooo - DUART test failed
  **oo - Walking bit memory test failed
  ***o - Memory address uniqueness test failed
  **** - Graphics test failed
  *o*o - Interrupt mask test failed

4D/30 and 4D/35

IP12 CPU board with Magnum Audio Option.

The following is an overview of the 4D/30 and 4D/35 CPU boards.

CPU Board Processor Clockspeed Cache (d/i) Cache (2nd) Floating Point
IP14 (sw: IP12) R3000A 30 MHz 64kb / 64kb none R3010A onboard
IP12 R3000A 60 MHz 64kb / 64kb none R3010A onboard

Both IP14 and IP12 need a CPU fan that is attached to the cover of the Emodule. The fan is powered by the connector at position H14 (may be covered by daughtercard). It is vital for safe operation that this fan is connected and running. Otherwise the CPU will cook itself to death.


4D/20 and 4D/25

Type:                   30pin SIMMs with parity (80-100ns)
Sockets:                16 (4 * 4 sockets)

Minimum configuration:  8 MB (4 * 2 MB SIMMs)
Maximum configuration:  32 MB (16 * 2 MB SIMMs)

To install 1MB modules 2 banks must be filled (8 MB are required), if installing 2MB modules all slots must be filled with the 2MB modules being installed in the first memory banks.

4D/30 and 4D/35

Type:                   proprietary SIMM (same as in Indigo R3000)
Sockets:                16 (4 * 4 sockets)

Minimum configuration:  8 MB (4 * 2 MB SIMMs)
Maximum configuration:  128 MB (16 * 8 MB SIMMs)

Note that only one set of 4MB modules may be installed (see below).


4D/20 and 4D/25

The 4D/20 and 4D/25 were available either as headless DataStation server systems or as workstations equipped with the Personal Iris graphics Option Eclipse.

4D/30 and 4D/35

The 4D/30 and 4D/35 were also available either as headless DataStation server systems or as workstations equipped with the Personal Iris graphics Option Eclipse. In addition to that they were also offered with Express graphics options similar to the ones used in the Indigo. This requires CN1/CB1 adapter/connector to plug the express boardsetinto the system.


Audio Hardware

Personal Iris models 4D/20 and 4D/25 have basic audio capabilities onboard. For audio in 4D/30 and 4D/35 an optional board is required that is plugged into a special slot on the mainboard. That additional board is called Magnum Audio Option and offers 16bit/stereo audio instead of the 8bit/mono audio that was offered on the earlier Personal Iris models.

Drives / SCSI Devices

The Personal Iris has a built in SCSI controller that supports the internal as well as the external SCSI devices. The SCSI connector is located on the back of machine itself (just right of the E-Module) and is also covered by the plastic skin. The internal drives connect to the same SCSI chain that is also available via that external centronics SCSI port. The SCSI controller is narrow SCSI, Western Digital 33C93A.

VME Expansion

All Personal Iris systems allow the owner to install double height 6U VME devices. The VME interface of the Personal Iris also supports busmaster devices which may directly access the main memory of the computer. Only the 4D/30 and 4D/35 models allow VME block transfer due to a new peripheral controller on the system board.

4D/20 and 4D/25 Connectors

On the back of the E-Module where the boards are located inside are the following connectors (hidden by a plastic cover):

  • AUI ethernet
  • Parallel Port
  • 2 DB9 serial ports
  • keyboard/mouse DB9 (IRIS4D style keyboard, Personal Iris type)
  • audio in, microphone, audio out

4D/30 and 4D/35 Connectors

The connectors are located on the back of the E-Module which is hidden beneath the plastic skins on the right side of the system (when viewed from the front):

  • AUI ethernet
  • Parallel Port
  • 2 DB9 serial ports
  • 2 8pin miniDIN serial ports
  • keyboard/mouse 6pin miniDIN (IRIS4D style keyboard, Indigo type)
  • microphone line in, line out, headphone, digital audio (optional)
  • VME

Note that the keyboard/mouse port is not PS/2 compatible. It can be used with the same keyboards/mice that were shipped with Indigo or Onyx systems.


  • CG2 / CG3
    A graphics output option for G, TG, 8-bit and 12-bit graphics on the Personal Iris, as well as GT and GTX graphics on the PowerSeries. The output format is RGB and can be genlocked to an external video source.
  • Video Creator (SCSI Version)
  • Video Framer
  • 6 port serial interface
    This is a 6U VME card which can be attached to the internal VME connectors to add 6 serial ports to the machine.


Personal Iris with front door open.

The Personal Iris chassis has been available in two versions, that look almost the same from the outside. Their main difference is that the newer one has the system drive mounted on a drivesled that is accessible from the front without actually opening the machine. It is called TFLU Chassis ("Totally Front Loading Unit").

width:     23,5 cm / 9.25"
height:    55,0 cm / 21.65"
depth:     50,0 cm / 19.69"

weight:    30 kg / ~65 lbs
There are no special signs for the various types of graphics installed. Server systems had "Data Station" printed on the drive door instead of "Personal Iris". The same boxes labeled "Iris File" are SCSI Vaults and do not contain any system boards. Instead of the boards the "Iris File" cases have 2 additional drivebays for 5.25" devices (see pictures).



There were VME based versions of the Personal Iris which have the same processor specs as the normal systems:

  V20  -  4D/20
V25 - 4D/25
V30 - 4D/30
V35 - 4D/35

All of these systems were composed of two 6U VME boards. The first card contained the CPU and external IO (keyboard/mouse, serial, parallel, ethernet, SCSI), while the second contained the VME controller, GIO-over-P2 logic, and up to 16/32/64 MB of RAM (16 for the V20, 32 for the V30 and V35). A third card for memory expansion could be added to V30 and V35 systems.

Graphics were provided as "G" (1 card), "TG" (2 cards), or "Elan" (4 cards if you want Z-buffer). The "G" and "TG" configurations allowed up to 4 graphics heads (see below) via GIO bus running over the P2 connectors of the VME bus. The "Elan" cards required higher noise immunity and have a special backplane "adapter" that runs across the P2 connectors and supports up to 2 heads (plans were made for up to 4, but practical bandwidth limitations kept it to 2).

Multihead Personal Iris

The 4D1-3.3 release notes mention this system among the newly supported hardware:  Multihead_Personal_Iris  For applications that
       demand multiple screens, the Multihead Personal Iris is now
       available.  This workstation incorporates up to four
       multiple Personal Iris graphics cards, each with their own
       monitor.  The system is based on the Irisette VME card set
       and is packaged in a Professional Iris chassis.

       In this release, only two screens are supported, the second
       of which is without window management.

Two-color cursor modification

Readers of This Old SGI may have recognized the bit on the "Mysterious Cursor Hardware Hack". Following the modification the Personal Iris also displays a two-color cursor like later SGI systems do (red with white border). jan-jaap has done the modification on a Personal Iris and has posted a summary with pictures on the Nekochan forum.

The upgrade seems to be a part of an official upgrade as not only it gives the system the two-color cursor but also is a feature recognized in the hinv output. A copy of the usenet article dated July, 11th 1991 which included a description of the modification is here. Note that it mentions, that the two-color cursor modification will prevent IRIX versions before 4.0 from booting.

Rebadged Systems

Relabeld Personal Iris systems were available from other companies. Among the known ones are:

  • Control Data: Dark Gray/Blue skins with Control Data logos painted on the front.
  • Bull: White Skins with Bull Logo on the Front.

Unlike the VME Personal Iris the Rebadged Systems have exactly the same dimensions as the original systems.


Operating System

Choosing an operating system.

The Personal Iris workstations were introduced when 4D1-3.x was available. Thus not all versions of this operating system relase can run on all Personal Iris systems. For the 4D/30 and 4D/35 a specific patch to the last 4D1-3.x releases is required to be able to use these versions at all.

General support for the Personal Iris can be found in the all platform releases of 4D1-4.x and IRIX 5.x. Support for the Personal Iris has ended with the release of the final version IRIX 5.3.

Powersupply Problems

Signs of failure: No signs of life.

Powersupply problems are not uncommon with these systems. Unplug the powercord, then open the opposite side of the E-Module and remove the sheetmetal. The powersupply has 2 replaceable fuses which are worth to check as well as the proper cabling. One fuse is on the small daughtercard, the other is next to that card and usually covered with a blue plastic cap.

If the PSU is completely dead and replacing with an original one or having it repaired it is not an option it might be a a possibility to swap another PSU into the Personal Iris. You may have seen pictures on the web that show systems equipped with PC powersupplys. This guide is intended to supply you with all the required information.

Battery Failure

Signs of failure: The system fails to boot and returns to PROM after issuing "Can't set tod clock"

This problem has so far been seen only on the later Personal Iris models (4D/30 and 4D/35). The earlier systems may not be affected and just boot with a faulty date/time.

While there also may be other causes, the by far most likely is an empty battery on the CPU board. The original battery is a 3V coin cell made by Duracell (DL2450). The battery is socketed so replacing it doesn't require any soldering. The cost of the battery is approximately 3 USD / 2 EUR.

4MB Memory Modules

Signs of failure: System doesn't work when more than one set of 4MB modules is installed.

This is a known problem and a flaw in the systems hardware of 4D/30 and 4D/35 systems which can not be fixed. The bottom line is, that only one 16MB kit (4x4MB) may be installed - there is no limitation regarding 8MB (4x2MB) or 32MB (4x8MB) kits.



Personal Iris 4D/35G

Personal Iris front with 4D/35 logo.

Personal Iris with front door open.

Personal Iris back.

Personal Iris with side panel removed.

Side view on Personal Iris.

Removing Personal Iris e-module.

Closup of Personal Iris 4D/35 connectors.

IP12+ CPU board with Magnum Audio Option.

GR1.5 graphics board with z-buffer and bitplane option.

5.25" harddisk in IRIS 4D sled.

SCSI Video Creator

Video Creator external version.

Connector panel of external Video Creator.

Interior view, showing the VME board.