Irix

SGI Irix

Irix History by Ryan Thoryk

IRIX is a computer operating system developed by Silicon Graphics, Inc. (SGI) to run natively on their 32- and 64-bit MIPS architecture workstations and servers. Based on UNIX System V with BSD extensions.

The current major version of IRIX is IRIX 6.5 which was released in May 1998. New minor versions are released every quarter. Through version 6.5.22, there were two branches of each release: a maintenance release that included only fixes to the original IRIX 6.5 code, and a feature release that included improvements and enhancements. An overlay upgrade from 6.5.x to the 6.5.22 maintenance release is available for free download, while version 6.5.23 and higher require an active Silicon Graphics support contract, despite only running on Silicon Graphics hardware.



The IRIX name was first used around the time of release 3.0 of the operating system for SGI's IRIS 4D series of workstations and servers, in 1988. Previous releases were identified only by the release number prefixed by "4D1-", eg. "4D1-2.2". The 4D1- prefix continued to be used in official documentation to prefix IRIX release numbers.



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

IRIX 4.0, released in 1991, replaced 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, incorporated certain features of UNIX System V Release 4, including ELF-format 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 was otherwise similar to IRIX 5.2. Later 6.x releases supported other members of the MIPS processor family in 64-bit mode. IRIX 6.3 was released for desktop systems only. IRIX 6.4 improved multiprocessor scalability for the Origin 2000 and Onyx2 systems and was marketed as "Cellular IRIX", although it only incorporated some features from the original Cellular IRIX distributed operating system project. IRIX 6.4 had severe reliability issues, limiting its adoption. IRIX development stabilized with IRIX 6.5, released in 1998. The current version of IRIX is 6.5.30, released in August 2006.



IRIX 6 is compliant with UNIX System V Release 4, UNIX 95 and POSIX (including 1e/2c draft 15 ACLs and Capabilities).

IRIX has strong support for real-time disk and graphics I/O. IRIX was one of the first Unix versions to feature a graphical user interface for the main desktop environment. IRIX was widely used in the computer animation industry and for scientific visualization due to its once-large application base.



IRIX uses the Indigo Magic Desktop, which by default uses the 4Dwm X window manager with a custom look designed using the Motif widget toolkit.

SCO OpenServer

SCO Open Server 6.x

SCO OpenServer, previously SCO UNIX and SCO Open Desktop (SCO ODT), is a closed source version of the Unix computer operating system developed by Santa Cruz Operation (SCO) and now maintained by the SCO Group.

SCO UNIX was the successor to SCO Xenix, derived from AT&T System V Release 3.2 with an infusion of Xenix device drivers and utilities. SCO UNIX System V/386 Release 3.2.0 was released in 1989 as the commercial successor to SCO Xenix. The base operating system did not include TCP/IP networking or X Window System graphics. Shortly after the release of this bare OS, SCO shipped an integrated product under the name of SCO Open Desktop, or ODT. 1994 saw the release of SCO MPX, an add-on SMP package.

At the same time, AT&T completed its merge of Xenix, BSD, SunOS and System V features into System V Release 4. SCO UNIX remained based on System V Release 3, but eventually added home-grown versions of most of the features of Release 4.

The 1992 releases of SCO UNIX 3.2v4.0 and Open Desktop 2.0 added support for long file names and symbolic links. 1995's rebranded OpenServer Release 5.0.0 added support for ELF executables and dynamically linked shared objects, and made many kernel structures dynamic.

SCO purchased the UnixWare system and its System V Release 4 code base from Novell in 1995. SCO was eventually able to re-use some code from that version of UnixWare in later releases of OpenServer. Until Release 6, this came primarily in the compilation system and the UDI driver framework and the USB subsystem written to it.

By the end of the 1990s, there were around 15,000 value-added resellers (VARs) around the world who provided solutions for customers of SCO's Unix systems.

SCO announced on August 2, 2000 that it would sell its Server Software and Services Divisions, as well as UnixWare and OpenServer technologies, to Caldera Systems, Inc. The purchase was completed in May 2001. The remaining part of the SCO company, the Tarantella Division, changed its name to Tarantella, Inc., while Caldera became Caldera International, and subsequently in 2002 the SCO Group.