View source for SGI Indigo

{{Short description|Workstations family by Silicon Graphics}}
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{{one source|date=January 2012}}
{{more citations needed|date=October 2019}}
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{{infobox computing device
| name = Silicon Graphics Indigo
| photo = [[File:Silicon Graphics Indigo (1).jpg|270px|frameless]]
| caption = 
| developer = '''[[Silicon Graphics International|SGI]]'''
| type = 3D [[Graphics workstation]]
| releasedate = 1991
| predecessor = [[SGI IRIS 4D]]
| successor = [[SGI Indigo2]]{{br}}[[SGI Crimson]]
| aka = SGI IRIS Indigo
| discontinued = 1995
}}[[File:SGI-indigo-front.jpg|thumb|SGI Indigo, front]]
[[File:SGI-indigo-back.jpg|thumb|SGI Indigo, back]]

The '''Indigo''', introduced as the '''IRIS Indigo''', is a line of [[workstation]] [[computer]]s developed and manufactured by [[Silicon Graphics|Silicon Graphics, Inc.]] (SGI). SGI first announced the system in July 1991.<ref name=indigo>{{Cite web|title=sgistuff.net : Hardware : Systems : Indigo|url=http://www.sgistuff.net/hardware/systems/indigo.html|access-date=2021-07-11|website=www.sgistuff.net}}</ref>

The Indigo is one of the most capable graphics workstations of its era, and was essentially peerless in the realm of hardware-accelerated three-dimensional graphics rendering. For use as a graphics workstation, the Indigo was equipped with a two-dimensional [[framebuffer]] or, for use as a 3D graphics workstation, with the [[Elan Graphics|Elan graphics]] subsystem including one to four [[Geometry Engine]]s (GEs). SGI sold a server version with no video adapter.

The Indigo's design is based on a simple cube motif in [[indigo]] hue. Graphics and other peripheral expansions are accomplished via the [[GIO]]32 expansion bus.

The Indigo was superseded generally by the [[SGI Indigo2]], and in the low-cost market segment by the [[SGI Indy]].

== Technical specifications ==
The first Indigo model (code-named ''Hollywood'') was introduced on July 22, 1991. It is based on the IP12 processor board, which contains a 32-bit [[MIPS Technologies|MIPS]] [[R3000A]] microprocessor soldered on the board and proprietary memory slots supporting up to 96&nbsp;MB of RAM.<ref name=indigo/><ref name=indigopr>{{cite press release|url=http://www.sgistuff.net/hardware/systems/documents/indigo-announce.txt|title=Silicon Graphics Introduces New RISC Personal Computer|date=July 1991|author=[[Silicon Graphics]]|website=sgistuff.net|access-date=September 4, 2024}}</ref>

The later version (code-named ''Blackjack'') was introduced in July 1992, priced from ${{Format price|12485}}, utilising a 64-bit MIPS [[R4000|R4000SC]] processor clocked externally at 50&nbsp;MHz.<ref name="computerworld19920713_sgi">{{ cite magazine | url=https://archive.org/details/computerworld2628unse/page/4/mode/1up | title=SGI unveils workstations, cuts prices | magazine=4 August 2025 | last1=Johnson | first1=Maryfran | date=13 July 1992 | access-date=4 August 2025 | pages=4 }}</ref> The model is based on the IP20 processor board, which has a removable processor module (PM1 or PM2) containing a R4000 (100&nbsp;MHz) or [[R4000#R4400|R4400]] processor (100&nbsp;MHz or 150&nbsp;MHz) that implements the MIPS-III instruction set. The IP20 uses standard 72-pin SIMMs with parity, and has 12 SIMM slots for a total of 384&nbsp;MB of RAM at maximum.<ref name=r4000indigo/>

A [[Motorola 56000]] DSP is used for Audio IO, giving it 4-channel 16-bit audio. [[Ethernet]] is supported on board by the [[Seeq Technology|SEEQ]] 80C03 chipset coupled with the HPC (High-performance Peripheral Controller), which provides the [[Direct memory access|DMA]] engine. The HPC interfaces primarily between the [[GIO]] bus and the Ethernet, [[SCSI]] (WD33C93 chipset) and the 56000 DSP. The GIO bus interface is implemented by the PIC (Processor Interface Controller) on IP12 and MC (Memory Controller) on IP20.

Much of the hardware design can be traced back to the [[SGI IRIS 4D]]/3x series, which shared the same [[memory controller]], [[Ethernet]], [[SCSI]], and optionally DSP as the IP12 Indigo. The 4D/30, 4D/35 and Indigo R3000 are all considered IP12 machines and run the same IRIX kernel. The Indigo R3000 is effectively a reduced cost 4D/35 without a VME bus. The PIC supports a VME expansion bus (used on the 4D/3x series) and GIO expansion slots (used on the Indigo). In all IP12, IP20, and IP22/IP24 (see [[SGI Indigo2]]) systems the HPC attached to the GIO bus.

== Graphics options ==

===Entry graphics===
For entry graphics, the 8-bit color frame buffer<ref name="fb.ind">{{Cite web |url=http://www.futuretech.blinkenlights.nl/indigo.html |title=Archived copy |access-date=2014-09-20 |archive-date=2019-04-12 |archive-url=https://web.archive.org/web/20190412014751/http://www.futuretech.blinkenlights.nl/indigo.html |url-status=dead }}</ref> comes in three versions. One version uses the system's GIO expansion bus. Another uses the main backplane like the XS, XZ, and Elan graphics options. The final is the same, but adds a second video output, giving the computer the ability to have two "heads", or monitors.

=== XS Graphics ===

The Indigo's XS Graphics option has a single GE7 Geometry Engine (GE), a RE3 Raster engine, a HQ2 Command engine, VC1, XMAP5. It is ideal for low-cost wireframe operations, compared to more powerful, and expensive options for textured graphics.<ref name="fb.ind" /> Part of SGI's Express line of graphics, four XS graphics options were produced for the Indigo: the XS-8 offers 8-bit color, with one VM2 video RAM module; the XS-Z adds the ZB-4 Z buffer; the XS-24 adds two VM2 modules and offers 24 color bits and 32 bits including brightness; and the XS-24Z adds a Z buffer.

=== XZ Graphics ===

The XZ graphics option is also a member of SGI's Express graphics line. It is similar to the XS-24z, but it includes a second GE7 Geometry Engine ASIC, doubling its geometry performance.

=== Elan Graphics ===

The highest performance graphics option offered for the Indigo, it is a member of SGI's Express graphics line. It is like the XS-24z and XZ, but has 4 GE7 Geometry Engine ASICs, giving it twice the performance of the XZ option.<ref name=r4000indigo>{{cite web|url=http://www.obsolyte.com/sgi_indigo/|title=SGI Indigo / Silicon Graphics R4000 Architecture|website=www.obsolyte.com}}</ref><ref name=elantr>{{cite web|url=http://www.sgistuff.net/hardware/graphics/documents/ElanTR.html|title=ElanTR - Elan Graphics Technical Report|website=www.sgistuff.net}}</ref>

== Operating system ==
The Indigo was designed to run [[IRIX]], SGI's version of [[Unix]].<ref name=indigopr/> The Indigos with R3000 processors are supported up to IRIX version 5.3, and Indigo equipped with an R4000 or R4400 processor can run up to IRIX 6.5.22.

Additionally, the free [[Unix-like]] operating system [[NetBSD]] has support for both the IP12 and IP20 Indigos as part of the sgimips port.<ref>{{Cite web|title=NetBSD/sgimips|url=http://wiki.netbsd.org/ports/sgimips/|access-date=2021-07-11|website=wiki.netbsd.org}}</ref>

==SGI timeline==
{{SGI computer timeline}}

== Popular culture ==
The Indigo was featured in ''[[Jurassic Park]]'' as the rendering system for [[Samuel L. Jackson]]'s character Arnold and his station to render graphics for Park Control Systems. It was paired to a [[Macintosh Quadra 700]].<ref>{{cite web | url=https://www.starringthecomputer.com/feature.html?f=11 | title=Starring the Computer - Jurassic Park }}</ref>

== References ==
{{Reflist}}

== External links ==
* [http://www.linux-mips.org/wiki/IP12 IP12 - LinuxMIPS]
* [http://www.megarat.com/indigo/ Technolust: The Indigo Page (Silicon Graphics - SGI)]
* [http://www.obsolyte.com/sgi_indigo/ SGI Indigo / Silicon Graphics R4000 Architecture]
* [https://forums.sgi.sh/index.php?threads/indigo-1-power-supply-basics.121/ Indigo Power Supply basics]

{{s-start}}
{{s-bef|rows=2|before = [[SGI IRIS 4D]] Personal}}
{{s-ttl|title = [[SGI IRIS 4D]] Personal}}
{{s-aft|rows=2|after = [[SGI Indy]]}}
{{s-ttl|rows=2|title = SGI IRIS Indigo |years = 1991 - 1995}}
{{s-bef|before = [[SGI IRIS 4D]] Professional}}
{{s-aft|after = [[SGI Indigo2]]}}
{{end}}

{{Silicon Graphics}}
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[[Category:SGI workstations|Indigo]]
[[Category:32-bit computers]]
[[Category:64-bit computers]]
[[Category:Computer-related introductions in 1991]]