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SGI Challenge M



         


The SGI Indigo2 and the SGI Challenge M were UNIX machines marketed by SGI from 1993 to 1997. The Indigo2 was a desktop workstation. The Challenge M was a server which differed from the Indigo2 only by the absence of graphics hardware. Indigo2 and Challenge M systems used either the SGI IP22, SGI IP26 or SGI IP28 motherboards. The SGI IP22 supported MIPS R4000, MIPS R4400 or MIPS R4600 processor modules, and the SGI IP26 and SGI IP28 supported MIPS R8000 and MIPS R10000 processor modules, respectively. All of these motherboards had 12 72-pin SIMM slots, which accept 70 ns or faster parity SIMMs. These slots are in three banks of four SIMMs, so each bank is 128 bits wide. The IP22 board accepted SIMMs up to 32 MB, for a maximum of 384 MB of memory. The IP26 and IP28 boards accept 64 MB SIMMs, but the maximum memory is officially listed as 640 MB, due to overheating problems in 768 MB configurations with early 64 MB SIMMs. With more recent SIMMs these boards can accept 768 MB without any problems. The MIPS R4000, 8 kB I-cache, 8 kB D-cache, no L2 cache)

All three of these motherboards supported EISA and GIO-64 expansion buses via a riser card. Early model riser cards had 3 physical GIO-64 slots and 4 EISA slots. Later riser cards had 4 physical GIO-64 slots, 3 EISA slots and 4 power connectors for SGI IMPACT graphics boards. In any case only two GIO-64 devices could be installed at one time, except for pairs of devices specially designed to share an interrupt, such as the IMPACT Compression and IMPACT Video boards. The multiplicity of physical slots exists to allow maximum flexibility with devices that filled multiple slots, such as the High IMPACT and Maximum IMPACT graphics boards.

Besides the three types of motherboards, another major factor dividing Indigo2 systems is support for SGI IMPACT graphics hardware. The IMPACT graphics boards draw more power than the GIO-64 bus can deliver, so the 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 graphics boards available for the Indigo2 were the pre-IMPACT boards, the SGI XL24, SGI XZ, SGI Elan and SGI Extreme, and the IMPACT boards, the SGI Solid IMPACT, the SGI High IMPACT and the SGI Maximum IMPACT. The XL24 was a 2D-only board, but it had a relatively high pixel fill rate and for some 2D tasks could perform as well as the much later High IMPACT board. The XL24 used one physical GIO-64 slot. The XZ, Elan and Extreme boards were built from differing numbers of the same GE (Geometry Engine) and RE (Raster Engine) chips. The XZ had two GEs and one RE, the Elan had four GEs and one RE, and the Extreme had eight GEs and two REs. The XZ and Elan boards took two physical GIO-64 slots, and the Extreme board took three slots. All of the pre-IMPACT 3D boards had a hardware Z-buffer, and none had hardware texture mapping.

The IMPACT boards were built around a later generation of higher-performance GEs and REs. The Solid IMPACT had one GE and one RE, and took up one physical IndyCam support)





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