Difference between revisions of "SGI O2"

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(Linux support)
(Further reading: Alternative designstudies@archive.org, once at alias.com)
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[http://www.futuretech.blinkenlights.nl/o2/ FutureTech Research: O2]
[http://www.futuretech.blinkenlights.nl/o2/ FutureTech Research: O2]
[http://web.archive.org/web/19970605013617/www.alias.com/Gallery/Design/desc/alchemy.html O2 Designstudies, once at alaias.com]
[[Category:SGI workstations|O2]]
[[Category:SGI workstations|O2]]

Revision as of 12:08, 5 June 2007

General information

The Silicon Graphics O2, introduced in 1996, is the successor to the Indy workstation. It comes in two flavours: the R5000/RM5271/RM7000 and the R10000/R12000. The former has space for two harddrives and the latter only for one, due to the size of the CPU heatsink. It is possible to put a R10000 into some R5k O2's by removing the metal separator between the mainboard and the harddrives, however, on some earlier models the separator is part of the chassis and cannot be removed short of cutting it out with a hacksaw.

The O2 was re-introduced with slight modifications as the O2+ in August 2001 only to be replaced by the Fuel in January 2002.

System architecture

The O2 features a proprietary high-bandwidth Unified Memory Architecture (UMA) that connects the various system components. A PCI bus is bridged onto the UMA with one slot available. It has a designer case and an internal modular construction. It has space for two SCSI drives mounted on special sleds (1 in the later R10000/R12000 models due to heat constraints) and an optional video capture / sound cassette mounted on the far left side. Further information on the design and construction of the O2 can be found in SGI service manuals on Techpubs. Detailed breakdown pictures and an IRIX hinv dump can be found here.

CPU and Memory options

The O2 comes in two distinct CPU flavours; the low-end MIPS 180-350 MHz R5000/R7000 based units and the higher-end 150-400 MHz R10000/R12000 based units. The 200 MHz R5000 CPUs with 1 MB L2-cache are generally noticeably faster than the 180 MHz R5000s with only 512 KB L2-cache. Also of note is that there is no 300 Mhz R5000 CPU, the O2 will incorrectly report the R5200 CPU as an R5000.

There is a hobbyist project that has successfully retrofitted a 600 MHz R7000 MIPS processor into the O2.

The motherboard has 8 proprietary 139-pin slots on the motherboard, accepting 4 paired sets of memory, referred to and sold as kits. The individual SDRAM DIMM modules come in 16 MB, 32 MB, 64 MB, and 128 MB sizes. The banks must be filled in order, and larger modules should be put in first. The O2 is expandable to 1 GB using 4 2x128 MB kits.


  • The CRM chipset that SGI developed for the O2, shares OpenGL calculations between CPU and chip. Due to the unified memory architecture, framebuffer memory comes from main memory, and there is effectively an 'unlimited' amount of texture memory. Another useful feature is that any incoming video data from the Audio/Video option can be used directly as an OpenGL texture without having to perform a copy or move.
  • ICE (Image Compression Engine -- a dedicated 64-bit R4000-based processor containing a 128-bit SIMD unit running at 66 MHz, which is used to accelerate various image and video operations)
  • OpenGL 1.1 + ARB image extensions

IRIX support

IRIX versions 6.3 and 6.5 (up to the latest overlay) are supported on this machine, however, only in 32-bit mode, due to the nature of the O2's internal architecture.

Linux support

There is official Linux support for the O2 in Debian 4.0 "Etch" as well as in Gentoo but only for R5000/R7000 O2s. Linux is not stable on R10000/R12000 CPUs due to a known issue with the way they handle speculative loads and stores, detailed here.

Installing Linux is made more difficult due to the O2's PROM being unable to read ISO9660 filesystems. There is a project to create bootable CDs here though most people use a 2nd computer as a PXE boot server to netboot an installer.

Add-on options

The O2 has only one available graphics option (CRM), which is built-in and cannot be replaced.

Media options include the Audio Option, Analog Video Option (AV1), Digital Video Option (AV2) and various PCI64 cards ranging from SCSI, Ethernet and Firewire to FDDI.

The O2 is unusual for a Silicon Graphics machine in that the base machine has a single HD15 connector for graphics output. There is also an add-in adapter available for the Silicon Graphics 1600SW flat panel display which supports an all-digital path from computer to display. A dual channel HD15 adapter is also available.

Further reading

SGIstuff: Hardware: Machines: O2

FutureTech Research: O2

O2 Designstudies, once at alaias.com