SGI Indigo² and Challenge M
The Indigo², code named Fullhouse, was a desktop workstation. The Challenge M was a server which differed from the Indigo² only by a slightly differently colored and badged case, and the absence of graphics and sound hardware. Both systems were based on the MIPS processors. Both systems supported EISA bus and SGI proprietary GIO64 expansion bus via a riser card.
SGI Indigo² workstation is a direct successor to the SGI Indigo model. Until the introduction of SGI Octane, SGI Indigo² was SGI's most powerful desktop system for 3D, visualization and high performance computing environments.
SGI Indigo² desktop workstations had two models: the teal case Indigo² - earlier model (original concept), and the later - often called IMPACT model - with purple colored case. Both looked the same from outside except color, and sub-model case badging. The available CPU types, the amount of RAM and GFX capabilities depends on the model or sub-model variation. There was a special version of the "Teal" Indigo², called Power Indigo²; this system had increased FPU (floating point unit) capabilities and used specially designed R8000 CPUs. It's natural that later IMPACT Indigo² workstation model gives more computational and visualization power, especially due to the introduction of R10000 series RISC CPU, and IMPACT graphics.
All Indigo² models use one of four distinct MIPS microprocessor variants: the 100 to 250 MHz MIPS R4000 and R4400, and the Quantum Effect Devices R4600 (IP22 mainboard); the 75 MHz MIPS R8000 (IP26 mainboard); and the 175 to 195 MHz R10000 (IP28 mainboard), which are featured in the last produced Indigo² model, the "IMPACT10000". Each microprocessor family differs in clock frequency, primary and secondary cache capacity.
All SGI Indigo² models have 12 SIMM slots on the motherboard. The Indigo² uses standard 36-bit parity 72-pin fast page mode SIMM memory. The memory modules are seated in groups of four. Indigo² could be expanded to a thermal specification maximum of either 384 MB or 512 MB RAM. The design of the memory control logic in R10000 machines supported up to 1 GB RAM, but the thermal output of older generation of DRAM chips necessitated the 512 MB limit. With newer, higher-density and smaller scale modules, 768 MB was easily within heat output specifications. Later, 128 MB modules allowed the full 1 GB with eight out of twelve sockets occupied.
All SGI Indigo² models can accommodate two 3.5" sized SCSI disk drives and one 5.25" sized SCSI CD-ROM drive inside bays on the front of the machine, using specially designed Indigo2 drive sleds with proprietary connectors. All of three drive bays are easily accessed when removing the stylish and recognisable Indigo2 front bezel. The internal SCSI bus speed of the Indigo2 is about 10Mbyte/s. The usual hard disk devices used by the manufacturer were narrow or SCSI-1 5200rpm and 7200rpm drives. All of the Indigo2 drive sleds have classic 50 pin female SCSI-1 connector + standard 4 pin power connector. Advanced U160 and U320 SCSI disk drives can also be used but then one needs appropriate adapters (80/68pin to 50pin SCSI).
10Mb on-board LAN interface, 100Mb LAN options were available from 3rd parties, either via EISA or GIO64 expansion cards. The two most known and widely used Indigo2 network cards are 3Com 3C597-TX 100Mbit EISA Card, and the Phobos G160 GIO64. The second one offers better overall performance due to using the superior GIO64 bus, which also has the effect of reducing the CPU utilization due to DMA transfers .
The graphics options available for the SGI Indigo² can be divided in two groups: the "pre-IMPACT" and the "MGRAS IMPACT" boards.
"Pre-IMPACT" options consisted of the following options: SGI XL24, SGI XZ, SGI Elan and SGI Extreme). These options are based on the same "Express Graphics" architecture from the original SGI Indigo, but feature improved performance.
The "MGRAS IMPACT" boards include: Solid IMPACT, High IMPACT, High IMPACT AA, and the Maximum IMPACT, and are also known as the IMPACT graphics family. These newer boards have a different architecture than the earlier designs. Physically, they appear to be similar to the older graphics options - the low-end Solid IMPACT board takes up a single GIO-64 slot, the mid-range High IMPACT takes up two GIO-64 slots, and the high end Maximum IMPACT takes occupies three. The High IMPACT and Solid IMPACT boards provides the same performance for non-textured tasks, while the Maximum IMPACT provides double the performance. The High IMPACT AA option has the geometry performance of a Maximum IMPACT, but is otherwise the same as the High IMPACT including the pixel fill performance.
The IMPACT graphics was the first desktop graphics system from SGI to offer texture mapping acceleration, though only the High IMPACT and Maximum IMPACT had this capability, and came with 1 MB of texture memory as standard. The Solid IMPACT card is named "Solid" due to its applications for solid (non-textured) modeling. When expanded by adding a TRAM (Texture RAM) module to the board, the amount of texture memory can be increased to 4 MB. Maximum IMPACT graphics require two of these modules due its two pixel units, although this does not upgrade them to 8 MB, with the two modules merely working in parallel to render twice as fast. At the time of its release, Maximum IMPACT graphics was the world's fastest available top-end desktop visualization solution. A Maximum IMPACT with 4 MB of texture memory and the correct graphics settings can play id Software's Quake 1, 2 or 3 with acceptable frame rates.
All graphics options for Indigo2 uses the standard 13W3 connector for connecting the monitor and another connector for 3D stereo glasses.
It is possible to have a dual-head Indigo2 by merely adding another Solid IMPACT card. Valid configurations include Solid/Solid, Solid/High, Solid/Maximum. Although there are four GIO-64 slots available and the High IMPACT takes up two, it is not possible to have a High/High configuration.
The IMPACT boards draw more power than the GIO-64 bus can deliver, so IMPACT-ready systems have additional power connectors on the expansion riser card, with a separate connection to the power supply. An IMPACT-ready Indigo² must have an IMPACT-ready riser card, an IMPACT-ready power supply, and a sufficiently recent PROM revision. The Indigo2's replacement, the SGI Octane, offered an upgraded XIO bus but featured the same graphics options, albeit in repackaged form.
More information can be found at:
- Remotely installing SGI IRIX 6.5 from a GNU/Linux server
- Indigo2 Wiki entry at nekochan.net
Linux - MIPS port: