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SGI Indigo R4000

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SGI IRIS Indigo R4000
SGI IRIS Indigo front (Rules666)
An IRIS Indigo from the front. The photograph does not show which processor board is fitted (Rules666, CC BY-SA 4.0)
Specifications
ManufacturerSilicon Graphics
TypeDesktop workstation
ReleasedJuly 1992[1]
Intro priceFrom US$12,485[1]
CPUMIPS R4000 at 100 MHz (50 MHz external) or R4400 at 100 or 150 MHz, on a removable CPU module (PM1 or PM2) on the IP20 board[1]
Memory12 sockets for 72-pin SIMMs with parity, up to 32 MB each; 384 MB maximum[1][2]
StorageThree internal 3.5-inch SCSI bays, drives mounted on sleds[3]
Display—
SoundMotorola 56000 DSP, four-channel 16-bit audio[1]
GraphicsEntry, XS-8, XS-24, XS-24Z, XZ or Elan[1][2]
ExpansionTwo GIO32-bis slots on the CPU board[2]
OS / FirmwareIRIX 4.0.5E to 6.5.22[3]
PredecessorIRIS Indigo R3000 (SGI Indigo)
SuccessorSGI Indigo² and SGI Indy[1]
CodenameBlackjack[1]

The SGI IRIS Indigo R4000, code-named Blackjack, is the second version of the IRIS Indigo desktop workstation. Silicon Graphics introduced it in July 1992, priced from $12,485.[1] It uses the IP20 processor board, which carries the processor on a removable module: an R4000 at 100 MHz, running at 50 MHz externally, or an R4400 at 100 or 150 MHz.[1] SGI's owner's guide calls it the IRIS Indigo R4000 family.[4] The chassis, graphics options and drive bays are the same as on the R3000 Indigo, so the procedures they share are in the SGI Indigo guides. The sections below cover what is different about the IP20 machines.[5][3]

Telling an R4000 Indigo from an R3000

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R3000 and R4000 Indigo compared
Check R3000 (IP12) R4000 family (IP20)
Front Graphics option printed on the front door Small badge with the graphics option and "4000"
Processor R3000A soldered to the board Large raised module under a metal shield, held by four screws
SIMM socket labels A1 to A4, B1 to B4, C1 to C4 S1A to S4A, S1B to S4B, S1C to S4C
SIMMs SGI's own, levered out with a removal tool 72-pin with parity, held by latches
hinv "33 MHZ IP12 Processor" "100 MHZ IP20 Processor" on a 100 MHz machine

[3][4][6][5][7]

IP20 board

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On the IP20 the GIO bus interface is in the MC memory controller; on the IP12 it is in the PIC.[1] The two expansion slots are GIO32-bis slots.[2] The hinv listing from one 100 MHz machine shows an R4000 with 8 KB instruction and 8 KB data caches and a 1 MB secondary cache, and a WD33C93B SCSI controller.[7]

A 100 MHz IP20 can be upgraded by replacing only the CPU module.[2] SGI's procedure for changing the module:[6]

  1. Shut down, switch off at the back, unplug the cables, remove the plastic front cover and open the front metal panel.
  2. Put on the wrist strap, clip it to the notch above the top drive slot, pull the two levers towards you and slide the CPU board out.
  3. Clip the strap to a metal part of the CPU board. Remove the four screws holding the module.
  4. Lift the module by its sides, rocking it from side to side to free the connector, and lift it away.
  5. Line the connector under the new module up with the socket, press down on the module connector until it is seated, and refit the four screws.
  6. Slide the board back in with the SIMMs facing left, with the notch in the top lever under the top edge of the chassis, and return the levers. Close the metal panel, tighten the thumbscrew and refit the front cover.

Memory controller warning

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After a memory upgrade IRIX may warn: "Warning: Revision C Memory Controller (MC) chip needed in order to properly operate with SIMMS of this type." Later IRIX releases word it differently. SGI added it when some memory modules had bugs. The TechPubs Wiki says that if hinv shows all the memory and there are no memory errors, it can be ignored. /usr/gfx/gfxinfo shows the MC revision.[3]

Memory

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Fit SIMMs in groups of four of the same capacity, in group A, B or C. SIMMs from an R3000 Indigo cannot be used.[4] The IP20 takes standard 72-pin fast-page-mode SIMMs with parity, 36 bits wide, up to 32 MB each.[1][8][2] To fit one, following SGI:[4]

  1. With the CPU board out and the SIMM sockets nearest you, hold the SIMM with the notch in its bottom corner on your left.
  2. Tip the top of the SIMM towards you and press it into the socket at 45 degrees.
  3. Tilt it up to vertical. It is seated when the latches on both sides hug its edges; it does not click.

To remove one, press the latches away from the SIMM with your thumbs, tip it towards you about 45 degrees and pull it out. No removal tool is needed.[4]

Upgrading from an R3000 Indigo

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  • An R3000 Indigo needs both the IP20 board and a different power supply.[2] One owner believes he damaged an Indigo supply by fitting an R4000 board to an R3000 chassis and supply.[9]
  • The Ethernet address is in an EEPROM on the backplane. An IP20 copies the address from the IP12's location when it is first fitted. If the IP12 is put back afterwards, the address is erased and has to be set again from the IP12's PROM, since the IP20's PROM does not allow it.[3][10] See the troubleshooting guide.
  • The old SIMMs cannot be reused.[4]

Software

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IRIX support for the R4000 Indigo began with 4D1-4.0.5E. IRIX 6.2 and 6.5 run on the R4000 models only, and 6.5.22 is the last release for them.[3] The IP20's PROM works with a wider range of CD-ROM drives than the IP12's, which does not recognise optical drives unless they have special firmware.[11]

Power supply

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The supply in one owner's R4400 machine is an ITT PowerSystems PEC4044B, part 6064459 Rev F.[12] Another owner reports that the 5 V rail of the R4000-variant supply is rated at 34 A, and that the supply will not start on the bench without a load on 5 V.[13] The supply was not designed by SGI and no schematic is known.[14] Repair notes from owners are in the SGI Indigo Capacitor Replacement Guide.

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References

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  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 "SGI Indigo", Wikipedia, en.wikipedia.org (revision of 25 February 2026).
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Kaya Kupferschmidt, "The SGI IRIS Indigo", hardware.majix.org, 2003, hardware.majix.org.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 "IRIS Indigo", TechPubs Wiki, tech-pubs.net (revision of 4 October 2025). Badges, drive bays, IRIX support, memory controller warning, Ethernet address.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Silicon Graphics, IRIS Indigo Workstation Owner's Guide, 007-9065-050, 1996, pp. 41–62 (File:SGI IRIS Indigo Workstation Owner's Guide (007-9065-050).pdf). SIMM types, socket labels, installing and removing R4000-family SIMMs.
  5. ↑ 5.0 5.1 Kaya Kupferschmidt, "Indigo R3000", hardware.majix.org, 2003, hardware.majix.org. hinv output from an IP12 machine; the two versions differ in processor and board but take the same graphics options.
  6. ↑ 6.0 6.1 SGI, 007-9065-050, pp. 141–150. Replacing the CPU board or CPU module.
  7. ↑ 7.0 7.1 Kaya Kupferschmidt, "Indigo R4000", hardware.majix.org, 2003, hardware.majix.org. hinv and gfxinfo output from a 100 MHz Elan machine.
  8. ↑ Kaya Kupferschmidt, "SGI Indigo Buyer's Guide", hardware.majix.org, 2003, hardware.majix.org. IP20 memory with parity.
  9. ↑ "Help me fix this PSU", IRIX Network forums, 27 July 2026, forums.irixnet.org.
  10. ↑ "IRIS Indigo -- 5.3 Network setup and MAC Address woes", IRIX Network forums, November 2021, forums.irixnet.org.
  11. ↑ "IRIS Indigo R4K - the re-build...", IRIX Network forums, August 2021, forums.irixnet.org.
  12. ↑ "Help identifying Indigo PSU components?", IRIX Network forums, 11 October 2025, forums.irixnet.org.
  13. ↑ "Indigo R4400 PSU Repair", IRIX Network forums, 18 April 2026, forums.irixnet.org.
  14. ↑ "Iris Indigo pops GFI when powered on", IRIX Network forums, weblacky, 28 October 2025, forums.irixnet.org.


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