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IRIX 6.5 Desktop
DeveloperSilicon Graphics
OS familyUnix (SVR3/SVR4)
Working stateHistoric as of December 2013
Source modelClosed source
Initial release1988 (1988)
Final release6.5.30 / 16 August 2006 (2006-08-16)
Marketing targetWorkstations, servers
Kernel typeMonolithic kernel
user interface
IRIX Interactive Desktop

IRIX (/ˈaɪrɪks/ EYE-ricks) is a discontinued operating system developed by Silicon Graphics (SGI) to run on the company's proprietary MIPS workstations and servers. It is based on UNIX System V with BSD extensions. In IRIX, SGI originated the XFS file system and the industry-standard OpenGL graphics system.


SGI originated the IRIX name in the 1988 release 3.0 of the operating system for the SGI IRIS 4D series of workstations and servers. Previous releases are identified only by the release number prefixed by "4D1-", such as "4D1-2.2". The "4D1-" prefix continued to be used in official documentation to prefix IRIX release numbers. Prior to the IRIS 4D, SGI bundled the GL2 operating system, based on UniSoft UniPlus System V Unix, and using the proprietary MEX (Multiple EXposure) windowing system.

IRIX 3.x is based on UNIX System V Release 3 with 4.3BSD enhancements, and incorporates the 4Sight windowing system, based on NeWS and IRIS GL. SGI's own Extent File System (EFS) replaces the System V filesystem.

IRIX 4.0, released in 1991, replaces 4Sight with the X Window System (X11R4), the 4Dwm window manager providing a similar look and feel to 4Sight.

IRIX 5.0, released in 1993, incorporates certain features of UNIX System V Release 4, including ELF executables. IRIX 5.3 introduced the XFS journaling file system.

In 1994, IRIX 6.0 added support for the 64-bit MIPS R8000 processor, but is otherwise similar to IRIX 5.2. Later 6.x releases support other members of the MIPS processor family in 64-bit mode. IRIX 6.3 was released for the SGI O2 workstation only. IRIX 6.4 improved multiprocessor scalability for the Octane, Origin 2000, and Onyx2 systems. The Origin 2000 and Onyx2 IRIX 6.4 was marketed as "Cellular IRIX", although it only incorporates some features from the original Cellular IRIX distributed operating system project.

The last major version of IRIX is 6.5, released in May 1998. New minor versions of IRIX 6.5 were released every quarter until 2005, and then four minor releases. Through version 6.5.22, there are two branches of each release: a maintenance release (identified by an "m" suffix) that includes only fixes to the original IRIX 6.5 code, and a feature release (with an "f" suffix) that includes improvements and enhancements. An overlay upgrade from 6.5.x to the 6.5.22 maintenance release was available as a free download, whereas versions 6.5.23 and higher required an active Silicon Graphics support contract.

A 2001 Computerworld review found IRIX in a "critical" state. SGI had been moving its efforts to Linux and the Windows-based SGI Visual Workstation but MIPS and IRIX customers convinced SGI to continue to support its platform through 2006. On September 6, 2006, an SGI press release announced the end of the MIPS and IRIX product lines. Production ended on December 29, 2006, with final deliveries in March 2007, except by special arrangement. Support for these products ended in December 2013 and they will receive no further updates.

Much of IRIX's core technology has been open sourced and ported by SGI to Linux, including XFS.

In 2009, SGI filed for bankruptcy and then was purchased by Rackable Systems, which was later purchased by Hewlett Packard Enterprise in 2016. All SGI hardware produced after 2007 is based on either IA-64 or x86-64 architecture, so it is incapable of running IRIX and is instead intended for Red Hat Enterprise Linux or SUSE Linux Enterprise Server. HPE has not stated any plans for IRIX development or source code release.


IRIX 6.5 is compliant with UNIX System V Release 4, UNIX 95, and POSIX (including 1e/2c draft 15 ACLs and Capabilities).

In the early 1990s, IRIX was a leader in Symmetric Multi-Processing (SMP), scalable from 1 to more than 1024 processors with a single system image. IRIX has strong support for real-time disk and graphics I/O. IRIX was widely used for the 1990s and 2000s in the computer animation and scientific visualization industries, due to its large application base and high performance. It still is relevant in a few legacy applications.

IRIX is one of the first Unix versions to feature a graphical user interface for the main desktop environment. IRIX Interactive Desktop uses the 4Dwm X window manager with a custom look designed using the Motif widget toolkit. IRIX is the originator of the industry standard OpenGL for graphics chips and image processing libraries.

IRIX uses the MIPSPro compiler for both its front end and back end. The compiler, also known in earlier versions as IDO (IRIS Development Option), was released in many versions, many of which are coupled to the OS version. The last version was 7.4.4m, designed for 6.5.19 or later. The compiler is designed to support parallel POSIX programming in C/C++, Fortran 77/90, and Ada. The Workshop GUI IDE is used for development. Other tools include Speedshop for performance tuning, and Performance Co-Pilot.


4Dwm is the window manager component of the IRIX Interactive Desktop normally used on Silicon Graphics workstations running IRIX. 4Dwm is derived from the older Motif Window Manager and uses the Motif widget toolkit on top of the X Window System found on most Unix systems. 4Dwm on IRIX was one of the first default graphical user interface desktops to be standard on a Unix computer system. 4Dwm refers to "Fourth dimension window manager" and has no relation to dwm.

Other X window managers that mimic the 4Dwm look and feel exist, such as 4Dwm theme for IceWM and 5Dwm which is a clone/compatible implementation of 4Dwm based on OpenMotif. 5Dwm support both the classic SGI look and a modern/polished look and feel with anti-aliased fonts and UTF-8 support.


See also


  1. ^ "SGI Support of MIPS IRIX Products Continues to December 2013". Silicon Graphics. Archived from the original on January 21, 2012. Retrieved January 15, 2022.
  2. ^ Ryan Thoryk (October 7, 2021). "History of IRIX". Retrieved December 25, 2021.
  3. ^ "IRIS Programming Tutorial V1.0" (PDF). Bitsavers. SGI. 1986. Retrieved December 25, 2021.
  4. ^ a b "History of IRIX". Retrieved November 18, 2022.
  5. ^ "SGIstuff : Software : Irix Versions". Retrieved November 2, 2007.
  6. ^ Tom Yager (November 19, 2001). "Vital Signs for Unix". Computerworld. Retrieved November 18, 2022.
  7. ^ "SGI - Services & Support: End of General Availability for MIPS IRIX Products". Archived from the original on October 19, 2007. Retrieved November 2, 2007.
  8. ^ "SGI Support of MIPS® IRIX® Products Changes December 2013". Retrieved March 3, 2014.
  9. ^ "IRIX Operating System (Unix)".
  10. ^ "Performance Co-Pilot IRIX® Base Software Administrator's Guide" (PDF). Silicon Graphics, Inc.
  11. ^ 5Dwm, The Window Manager