Indigo2 Model Summary

Silicon Graphics FAQs
Looking for IRIX or Solaris expertise? Visit my UNIX Consultancy website.

teal Silicon Graphics Indigo2 R4600purple Silicon Graphics Indigo2 R10k

Until the introduction of the Octane, the Indigo 2 was SGI’s top end workstation. However, performance is still excellent and it still makes a very fast and useable workstation. Recently, prices have been plummeting, and an R10000 MaxImpact Indigo 2 represents superb value for money.

There are two different variants of the Indigo 2 – one with a green (called teal) case, and one with a purple case. RAM, CPU types, and graphics options available vary between the two.

CPU Options
CPU Type Speed (mhz) Secondary Cache Size
R4400SC 150 1MB
R4400SC 200 1MB
R4400SC 250 2MB
R10000SC 175 1MB
R10000SC 195 1MB

There are other CPU options, mostly the older R4000 and R4600 processors, which have the same specification as those available to the Indy. More can be found here.

You can upgrade an R4400 Indigo 2 to an R10000 processor. You will need a new motherboard, new powersupply, new processor module (duh! :-) and you may also need to replace the expansion backplane. However, it would probably work out cheaper to just sell your old machine and buy a newer one.


R4400 based Indigo 2 machines have 12 SIMM slots, giving 3 banks of 4 slots. They can take 4mb, 8mb, 16mb or 32mb 72pin parity SIMMs, giving a total of 384mb.

R10000 based Indigo 2 machines also have 12 SIMM slots, with 3 banks of 4 slots. They can take all the above SIMM sizes (again, 72pin parity) but can also take 64mb SIMMs, giving a total of 768mb RAM.

It appears it is possible to squeeze in 1GB RAM into late model R10k machines – Ian’s site has the info here.

Graphics options:

This is the tricky one :-) The Indigo 2 has a wealth of different graphics options, and two different expansion backplanes that support different options.

The earlier, green (called Teal) cased Indigo 2 has the following options:

  • 24bit XL – no hardware acceleration, basically a 2D card

  • 24bit XZ – 2 geometry engines, hardware Z buffers

  • 24bit EX (Extreme Graphics) – 8 geometry engines, hardware Z buffers

Later Teal Indigo 2s had an upgraded XZ card with 4 GEs, although I’ve never seen one.

The later, purple cased Indigo 2 has the following options:

  • Solid Impact – 1 GE(1), 1 RE(2), no hardware texture mapping

  • High Impact – 1 GE, 1 RE, hardware texture mapping, 1MB or 4MB TRAM(3)

  • High Impact (High-AA)(4) – 2 GEs, 1 RE, hardware texture mapping, 1MB or 4MB TRAM

  • Max Impact – 2 GEs, 2 REs, hardware texture mapping, 1MB or 4MB TRAM

(1) GE – Geometry Engine
(2) RE – Raster Engine
(3) TRAM – Texture RAM
(4) The High-AA board is a bit rare, and I haven’t seen it mentioned anywhere in SGI literature, but it’s basically a High Impact that carries out some operations at Max Impact speeds (most notably Anti-Aliasing, hence the AA)

Note that it’s possible to mix and match graphics boards to create a dual-head workstation. A Max-Impact/Solic Impact R10k is a truly splendid workstation :-)

If you want to upgrade a teal Indigo 2 to IMPACT graphics, you not only need to get the required board sets, but you will also need to replace the expansion backplane, and probably the power supply as well.


  • External fast SCSI (2nd channel)

  • 2 Mac-compatible serial ports (RS422)

  • PS/2 keyboard and mouse

  • 10-BaseT or AUI ethernet

  • Audio I/O (microphone, headphone, line-in, etc.)

  • Bi-directional parallel port

  • 3 EISA slots, and 2 GIO-64 slots


The Indigo 2 has a decent amount of space inside for various drive configurations. There is space for 2 3.5″ hard drives, an externally accessible 5.25″ slot for a CD drive, and an externally accessible 3.5″ full height slot, for either a Floptical drive, or a DAT drive.
The internal devices are connected to one SCSI channel, and the external devices are connected to another, so you can spread devices across 2 seperate channels to improve I/O performance if needed.

All 3.5" and 5.25" devices are mounting on custom SGI sleds. These sleds present a 50pin SCSI cable to the device, and have a custom 80pin connecter which plugs into the Indigo2 chassis – it looks like SCA.

The internal SCSI bus is SCSI-2 10mb/s. Any non-HVD drive will work in an Indigo2. If the drive doesn’t have a 50pin connector, who will need to buy and fit a converter. However, note that the combined depth of a hard drive + converter may be too much to fit on the sleds.

More information:

Owner’s Guides and Datasheets

The Owner’s Guide for the Indigo2 can be found on Techpubs, as can the Owner’s Guide for the Indigo2 Impact.

A local copy for the Indigo2 can be found here PDF icon, as well as for the Indigo2 Impact. PDF icon

A local copy of the Indigo2 Impact datasheet can be found here. PDF icon

Comments Off on Indigo2 Model Summary