IRIX is a discontinued operating system developed by Silicon Graphics to run on the company's proprietary MIPS workstations and servers. It is a variety of UNIX System V with BSD extensions. In IRIX, SGI originated the XFS file system and the universally adopted industry-standard OpenGL graphics system. The last major version of IRIX is IRIX 6.5, which was released in May 1998. New minor versions of IRIX 6.5 were released every quarter until 2005; since then there have been four further minor releases. Through version 6.5.22, there are two branches of each release: a maintenance release that includes only fixes to the original IRIX 6.5 code, and a feature release 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.
History
SGI first used the IRIX name from 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-", e.g. "4D1-2.2". The 4D1- prefix continued to be used in official documentation to prefix IRIX release numbers. 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 replaces the System V filesystem. IRIX 4.0, released in 1991, replaces 4Sight with the X Window System, the 4Dwmwindow 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. IRIX development stabilized with IRIX 6.5, released in 1998. The last version of IRIX is 6.5.30, released in August 2006. 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 6 September 2001, an SGI press release announced the end of the MIPS and IRIX product lines. Production ended on 29 December 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. , due to the bankruptcy of Silicon Graphics in 2009 and its subsequent purchase by Rackable Systems, who later was purchased by HP Enterprise in 2016, all SGI-badged hardware produced after 2007 is incapable of running IRIX, being based on either IA-64 or x86-64 architecture and designed to run Red Hat Enterprise Linux or SUSE Linux Enterprise Server. HPE has not stated any public plans for IRIX development or source code release.
Features
IRIX 6.5 is compliant with UNIX System V Release 4, UNIX 95, and POSIX. In the early 1990s, IRIX was a leader in Symmetric Multi-Processing, 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 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.
Hobbyist Use
IRIX has attracted a small but dedicated fanbase of Silicon Graphics hardware who are attracted to various aspects of the operating system and corresponding hardware. This includes the operating system itself, especially its 3D graphics software such as Alias Maya/PowerAnimator and SoftImage, and the HPC elements of the hardware. This hobbyist community is notable for preserving various beta versions of Acclaim Entertainment games from a lot discovered in 2017 including Turok and NBA Jam.
