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IBM-AIX logo20080906.png
Company / developer IBM
Programmed in C
OS family Unix
Working state Current
Source model Closed source
Latest stable release 6.1 / November, 2007
Marketing target Workstation, Server
Available language(s) English
Available programming languages(s) C
Supported platforms ROMP, IBM POWER, PowerPC, IBM PS/2, System/370, ESA/390
Kernel type Dynamic Extendable
Default user interface Common Desktop Environment
License Proprietary
Official Website IBM AIX

AIX (Advanced Interactive eXecutive) is the name given to a series of proprietary operating systems sold by IBM for several of its computer system platforms, based on UNIX System V with 4.3BSD-compatible extensions.

AIX runs on 32-bit or 64-bit IBM POWER or PowerPC CPUs (depending on version) and can address up to 32 terabytes (TB) of random access memory.



AIX Version 1, introduced in 1986 for the IBM 6150 RT 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 IBM 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 SCO vs. IBM, less than forty licenses for the finished Monterey Unix were ever sold before the project was terminated in 2002.

AIX 6 was announced in May 2007 and ran an open beta from June 2007 until the general availability (GA) of AIX 6.1 on November 9, 2007. Major new features in AIX 6.1 included full role-based access control, workload partitions (which enable application mobility), enhanced security (Addition of AES encryption type for NFS v3 and v4) and live partition mobility on the POWER6 hardware.


SCO lawsuit

In the SCO v. IBM lawsuit filed 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.

On 2007-08-10 the U.S. district court ruled that SCO does not own the copyrights to the Unix operating system.[1]

On August 24, 2009, the U.S. Court of Appeals for the Tenth Circuit reversed the portion of the August 10, 2007 district court summary judgment that Novell owned the copyright to Unix. As a result, SCO may now pursue its ownership of the Unix copyrights at trial. AppealRuling.pdf

Supported hardware platforms

IBM 6150 RT

The original AIX (sometimes called AIX/RT) was developed for the IBM 6150 RT workstation by IBM in conjunction with INTERACTIVE Systems Corporation, who had previously ported UNIX System III to the IBM PC for IBM as PC/IX. Installation media consisted of eight 1.2M floppy disks. The RT was based on the ROMP chip, the first commercial RISC chip, based on a design, the IBM 801, pioneered at IBM Research.

One of the novel aspects of the RT design was the use of a microkernel, called Virtual Resource Manager (VRM). The keyboard, mouse, display, disk drives and network were all controlled by a microkernel. One could "hotkey" from one operating system to the next using the Alt-Tab key combination. Each OS in turn would get possession of the keyboard, mouse and display. Besides AIX v2, the PICK OS also utilized this microkernel.

Much of the AIX v2 kernel was written in the PL/I programming language, which proved troublesome during the migration to AIX v3.[citation needed] AIX v2 included full TCP/IP networking, as well as SNA and two networking file systems: NFS, licensed from Sun Microsystems, and Distributed Services (DS). DS had the distinction of being built on top of SNA, and thereby being fully compatible with DS on the IBM midrange AS/400 and mainframe systems. For the graphical user interfaces, AIX v2 came with the X10R3 and later the X10R4 and X11 versions of the X Window System from MIT, together with the Athena widget set. Compilers for Fortran and C were available. One of the more popular desktop applications was the PageMaker desktop publishing software.

IBM PS/2 series

AIX PS/2 (also known as AIX/386) was developed by Locus Computing Corporation under contract to IBM. AIX PS/2, first released in 1989, ran on IBM PS/2 personal computers with Intel 386 and faster processors.

IBM mainframes

In 1988, IBM announced AIX/370, also developed by Locus Computing. AIX/370 was IBM's first attempt to offer Unix-like functionality for their mainframe line, specifically the System/370. AIX/370 was released in 1990 with functional equivalence to System V Release 2 and 4.3BSD as well as IBM enhancements. With the introduction of the ESA/390 architecture, AIX/370 was replaced by AIX/ESA in 1991, which was based on OSF/1, and also ran on the System/390 platform. This development effort was made partly to allow IBM to compete with Amdahl UTS.[citation needed] Unlike AIX/370, AIX/ESA ran both natively as the host operating system, and as a guest under VM. AIX/ESA, while technically advanced, had little commercial success, partially because UNIX functionality was added as an option to the existing mainframe operating system, MVS, which became MVS/ESA OpenEdition in 1999.[citation needed]

POWER/PowerPC-based systems

The release of AIX version 3 (sometimes called AIX/6000) coincided with the announcement of the first IBM RS/6000 models. The RS/6000 was unique in that it not only outperformed all other machines in integer compute performance, but also beat the competition by a factor of 10 in floating-point performance.[citation needed]

Releases of AIX version 3 also took advantage of the developments in the POWER architecture.

AIX v3 innovated in several ways on the software side. It was the first operating system to introduce the idea of a journalling file system, JFS, which allowed for fast boot times by avoiding the need to fsck the disks on every reboot. Another innovation was the introduction of shared libraries, which avoided the need for an application to statically link to the libraries it used. The resulting smaller binaries used less of the hardware RAM, to run, and used less of the disk space to install. Besides improving performance, it was a boon to developers: executable binaries could be in the 10s of kilobytes instead of a megabyte for an executable statically linked to the C library. AIX v3 also ditched the microkernel of AIX v2, a contentious move that resulted in v3 being somewhat more "pure" (and containing no PL/1 code) than v2.

Other notable subsystems included:

  • IRIS GL, a 3D rendering library, the progenitor of OpenGL. IRIS GL was licensed by IBM from SGI, then a small company which had sold only one thousand machines to date. SGI also provided the low-end graphics card for the RS/6000, capable of drawing 20,000 gouraud-shaded triangles per second. The high-end graphics card was designed by IBM, a follow-on to the mainframe-based IBM 5080, capable of rendering 990K vectors per second.
  • PHIGS, another 3D rendering API, popular in automotive CAD/CAM circles, and at the core of CATIA.
  • Full implementation of version 11 of the X Window System, together with Motif as the recommended widget collection and window manager.
  • Network file systems: NFS from Sun; AFS, the Andrew File System; and DFS, the Distributed File System.
  • NCS, the Network Computing System, licensed from Apollo Computer (later acquired by HP)
  • DPS on-screen display system. This was notable as a "plan B", in case the X11+Motif combination failed in the marketplace. However, it was highly proprietary: only Sun and Next supported it in addition to IBM. This, in the face of the open systems challenge of X11+Motif and its lack of 3D capability, cemented its failure in the marketplace.

As of 2007, the current release of AIX runs on the RS/6000 and System p, BladeCenter JS-series, IntelliStation POWER, and System i5 platforms.

Apple Network Servers

The Apple Network Server systems were PowerPC-based systems designed by Apple Computer to have numerous high-end features that standard Apple hardware did not have, including swappable hard drives, redundant power supplies, and external monitoring capability. These systems were more or less based on the Power Macintosh hardware available at the time but were designed to use AIX (versions 4.1.4 or 4.1.5) as their native operating system in a specialized version specific to the ANS.

AIX was only compatible with the Network Servers and was not ported to standard Power Macintosh hardware. Not to be confused is A/UX, Apple's earlier version of Unix for 68k-based Macintoshes.

IA-64 systems

As part of Project Monterey, a beta test version of AIX 5L was released for the IA-64 (Itanium) architecture in 2001, but this was abandoned before it became an official product due to the lack of interest in the finished Project Monterey system, as well as the overall lack of uptake of the IA-64 architecture by a skeptical marketplace, which largely gravitated towards the Project Trillian port of Linux as the primary platform OS.[citation needed]


AIX 5.3 welcome banner
The default login banner for AIX 5.3 on Power PC

POWER/PowerPC releases

IBM PS/2 releases

  • AIX PS/2 v1.1, 1989
    • last version was 1.3, 1992.

IBM 6150 RT releases

  • AIX v1.0, 1986
  • AIX v2.0
    • last version was 2.2.1.

User interfaces


The Common Desktop Environment (CDE) is AIX's default graphical user interface. As part of Linux Affinity and the free AIX Toolbox for Linux Applications (ATLA), open-source KDE and GNOME desktop are also available.

System Management Console

SMIT is the System Management Interface Tool for AIX. It allows a user to navigate a menu hierarchy of commands, rather than using the command line. Invocation is typically achieved with the command smit. Experienced system administrators make use of the F6 function key which generates the command line that SMIT will invoke to complete the proposed task.

SMIT also generates a log of commands that are performed in the smit.script file. The smit.script file automatically records the commands with the command flags and parameters used. The smit.script file can be used as an executable shell script to rerun system configuration tasks. SMIT also creates the smit.log file, which contains additional detailed information that can be used by programmers in extending the SMIT system.

smit and smitty refer to the same program, though smitty invokes the text-based version, while smit will invoke an X Window System based interface if possible; however, if smit determines that X Window System capabilities are not present, it will present the text-based version instead of failing. Determination of X Window System capabilities is typically performed by checking for the existence of the DISPLAY variable.

See also


External links


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