AIX (Advanced Interactive eXecutive, pronounced ,) is a series of proprietary Unix operating systems developed and sold by IBM for several of its computer platforms.
Background
Originally released for the IBM RT PC RISC workstation in 1986, AIX has supported a wide variety of hardware platforms, including the IBM RS/6000 series and later Power and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server. It is currently supported on IBM Power Systems alongside IBM i and Linux.
AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is certified to the UNIX 03 and UNIX V7 marks of the Single UNIX Specification, beginning with AIX versions 5.3 and 7.2 TL5 respectively. Older versions were previously certified to the UNIX 95 and UNIX 98 marks.
AIX was the first operating system to have a journaling file system, and IBM has continuously enhanced the software with features such as processor, disk and network virtualization, dynamic hardware resource allocation (including fractional processor units), and reliability engineering ported from its mainframe designs.
History
Unix started life at AT&T's Bell Labs research center in the early 1970s, running on DEC minicomputers. By 1976, the operating system was in use at various academic institutions, including Princeton, where Tom Lyon and others ported it to the S/370, to run as a guest OS under VM/370. This port would later grow out to become UTS, a mainframe Unix offering by IBM's competitor Amdahl Corporation. IBM's own involvement in Unix can be dated to 1979, when it assisted Bell Labs in doing its own Unix port to the 370 (to be used as a build host for the 5ESS switch's software). In the process, IBM made modifications to the TSS/370 hypervisor to better support Unix.
It took until 1985 for IBM to offer its own Unix on the S/370 platform, IX/370, which was developed by Interactive Systems Corporation and intended by IBM to compete with Amdahl UTS. The operating system offered special facilities for interoperating with PC/IX, Interactive/IBM's version of Unix for IBM PC compatible hardware, and was licensed at $10,000 per sixteen concurrent users.
AIX Version 1, introduced in 1986 for the IBM RT PC workstation, was based on UNIX System V Releases 1 and 2. In developing AIX, IBM and Interactive Systems Corporation (whom IBM contracted) also incorporated source code from 4.2 and 4.3 BSD UNIX.
Among other variants, IBM later produced AIX Version 3 (also known as AIX/6000), based on System V Release 3, for their POWER-based RS/6000 platform. Since 1990, AIX has served as the primary operating system for the RS/6000 series (later renamed IBM eServer pSeries, then IBM System p, and now IBM Power Systems). AIX Version 4, introduced in 1994, added symmetric multiprocessing with the introduction of the first RS/6000 SMP servers and continued to evolve through the 1990s, culminating with AIX 4.3.3 in 1999. Version 4.1, in a slightly modified form, was also the standard operating system for the Apple Network Server systems sold by Apple Computer to complement the Macintosh line.
In the late 1990s, under Project Monterey, IBM and the Santa Cruz Operation planned to integrate AIX and UnixWare into a single 32-bit/64-bit multiplatform UNIX with particular emphasis on running on Intel IA-64 (Itanium) architecture CPUs. A beta test version of AIX 5L for IA-64 systems was released, but according to documents released in the SCO v. IBM lawsuit, less than forty licenses for the finished Monterey Unix were ever sold before the project was terminated in 2002. In 2003, the SCO Group alleged that (among other infractions) IBM had misappropriated licensed source code from UNIX System V Release 4 for incorporation into AIX; SCO subsequently withdrew IBM's license to develop and distribute AIX. IBM maintains that their license was irrevocable, and continued to sell and support the product until the litigation was adjudicated.
AIX was a component of the 2003 SCO v. IBM lawsuit, in which the SCO Group filed a lawsuit against IBM, alleging IBM contributed SCO's intellectual property to the Linux codebase. The SCO Group, who argued they were the rightful owners of the copyrights covering the Unix operating system, attempted to revoke IBM's license to sell or distribute the AIX operating system. In March 2010, a jury returned a verdict finding that Novell, not the SCO Group, owns the rights to Unix.