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Apple Unix with Netscape.png
A/UX 3.0.1 with Finder, CommandShell and Netscape
DeveloperApple Computer
OS family
Working stateHistoric
Source modelClosed source
Initial releaseFebruary 1988; 30 years ago (February 1988)[1]
Latest release3.1.1 / 1995; 23 years ago (1995)
Kernel typeMonolithic kernel

A/UX is a discontinued Apple Computer implementation of the Unix operating system for some of its Macintosh computers. It was Apple's first attempt at developing and marketing a Unix-based operating system to run on its Macintosh line.[2] A/UX requires a 68k-based Macintosh with an FPU and a paged memory management unit (PMMU), and various versions run on the Macintosh II, SE/30, Quadra and Centris series of machines. A/UX was first released in 1988, with the final version of 3.1.1 released in 1995. It is not related to Apple's current Unix branded[3] macOS.

Described by InfoWorld as "an open systems solution with the Macintosh at its heart",[4] the operating system is based on UNIX System V Release 2.2. It includes some additional features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It is POSIX and System V Interface Definition (SVID) compliant and includes TCP/IP networking from version 2 onward. Having a Unix-compatible, POSIX-compliant operating system made it possible for Apple to bid for large contracts to supply computers to U.S. federal government institutes.[5][6]


A/UX 3.x provides a graphical user interface with the familiar Finder windows, menus, and controls. The A/UX Finder is not the same program as the System 7 Finder, but a customized version adapted to run as a Unix process and designed to interact with the underlying Unix kernel and file systems. A/UX 3.x includes a CommandShell terminal program, which offers a command line interface to the underlying Unix system. An X Window System server application (called MacX) with a terminal program can also be used to interface with the system and run X applications directly in the Finder. Alternatively, the user can choose to run a full X11R4 session without the Finder.[4]

Being based upon Apple's compatibility layer, A/UX can run Macintosh System 7.0.1, Unix, and "hybrid" applications. A hybrid application uses both Macintosh and Unix system functions: for example, a Macintosh application which calls Unix system functions, or a Unix application which calls Macintosh Toolbox (e.g. QuickDraw) functions. The compatibility layer uses some existing Toolbox functions in the computer's ROM, while other function calls are translated into native Unix system calls.[citation needed]

A/UX includes a utility called Commando (similar to a tool of the same name included with Macintosh Programmer's Workshop) to assist users with entering Unix commands. Opening a Unix executable file from the Finder opens a dialog box that allows the user to choose command-line options for the program using standard controls such as radio buttons and check boxes, and display the resulting command line argument for the user before executing the command or program. This feature is intended to ease the learning curve for users new to Unix, and decrease the user's reliance on the Unix manual. A/UX has a utility that allowed the user to reformat third party SCSI drives in a way such that they can be used in other Macs of that era.[4]

A/UX runs only on 68k-based Macintoshes with a floating point unit (FPU) and a paged memory management unit (PMMU),[7] and even then only on select models. For example, the Quadra 840AV, Apple's fastest 68k Macintosh, cannot run A/UX.[8]


A/UX 1.0 was announced at the February 1988 Uniforum conference, seven months behind schedule.[1] Based on AT&T's Unix System V.2.2 with additional features from BSD Unix, it was initially sold bundled with a Macintosh II for $8597 (more for a larger monitor, less for a Mac II upgrade kit).[1][9] It was initially aimed at existing Unix customers, universities and VARs.[9] Third-party software announced with the system's first release includes the Ingres database, StatView, developer tools, and various productivity software packages.[1][10] Networking support consists of TCP/IP, AppleTalk and NFS implementations, developed by UniSoft.[11]

The product's first release runs less than 10% of the Macintosh application base, and cannot display more than one System 7 program onscreen at any one time. The next version was to amend this situation, as well as add the Finder, X Window System and compliance with the draft POSIX standard.[12] X and POSIX support are in place as of A/UX 1.1, released 1989.[13]

In 1991, Apple formed a new business division for enterprise systems to serve "large businesses, government, and higher education". Based upon A/UX, the division intended to address the facts that the company was admittedly "not a major player" in the Unix market and had performed merely "quiet" marketing of the operating system, intending to improve in 1992.[14]

In November 1991, Apple launched A/UX 3.0, planning to synchronize the two ongoing release schedules of A/UX and System 7. At that time, the company also preannounced A/UX 4.0, expected for release in 1993 or 1994. The announcement expounded upon the technology partnership between Apple and IBM, expecting to merge Apple's user-friendly graphical interface and desktop applications market with IBM's highly scalable Unix server market, and allowing the two companies to enter what Apple believed to be an emerging "general desktop open systems market". The upcoming A/UX 4.0 would target the PowerOpen Environment ABI, merge features of IBM's AIX variant of Unix into A/UX, and use the OSF/1 kernel from the Open Software Foundation. A/UX 3.0 would serve as an "important migration path" on the migration path to this new system, making Unix and System 7 applications compliant with PowerOpen.[4] The future A/UX 4.0 and AIX operating systems were intended to run on a variety of IBM's POWER and PowerPC hardware, and of Apple's PowerPC based hardware.[14]

In 1992, a C2-level secure version of A/UX was released.[15]

Contrary to all announcements, Apple eventually abandoned all plans for A/UX 4.0, never releasing the product. In its place, the company deployed a mid-1990s platform of Apple Network Server hardware running a customized IBM AIX operating system.[16] Following Apple's 1996 acquisition of NeXT, Apple introduced 1999's Mac OS X Server, based on the Unix-like NeXTSTEP operating system.

The final release of A/UX is version 3.1.1 of 1995.[17] Apple abandoned the A/UX platform completely by 1996.[citation needed]

Timeline of Macintosh operating systems
Apple–Intel architecturePower Mac G5Power Mac G4iMac G3Power MacintoshMacintosh QuadraMacintosh PortableMacintosh SE/30Macintosh IIMacintosh PlusMacintosh 128KA/UXA/UXA/UXmacOS MojavemacOS High SierramacOS SierraOS X El CapitanOS X YosemiteOS X MavericksOS X Mountain LionMac OS X LionMac OS X Snow LeopardMac OS X LeopardMac OS X TigerMac OS X PantherMac OS X 10.2Mac OS X 10.1Mac OS X 10.0Mac OS X Public BetaMac OS X Server 1.0MacWorks XLMacWorks XLSun RemarketingMacWorks XLMac OS 9Mac OS 9Mac OS 9Mac OS 8Mac OS 8Mac OS 8Mac OS 8System 7System 7System 7System 7System 6Classic Mac OSClassic Mac OSClassic Mac OSClassic Mac OSSystem 1Finder (software)Finder (software)Finder (software)Finder (software)Finder (software)Finder (software)Finder (software)Finder (software)


BYTE in 1989 listed it as among the "Excellence" winners of the BYTE Awards, stating that it "could make Unix the multitasking operating system of choice during the next decade" and challenge OS/2.[18] Compared to contemporary workstations from other Unix vendors, however, the Macintosh hardware lacks features such as demand paging. The first two versions A/UX consequently suffer from poor performance,[13] and poor sales.[4] Users also complained about the amount of disk space it uses.[6] The first version was also criticized in a 1988 InfoWorld review for having a user interface that was still largely command-driven, like in other Unix variants, rather than graphical and mouse-driven; its networking support was praised, though.[19]

In the August 1992 issue of InfoWorld, the same author favorably reviewed A/UX 3.0, describing it as "an open systems solution with the Macintosh at its heart" where "Apple finally gets Unix right". He praised the GUI, single-button point-and-click installer, one year of personal tech support, the graphical help dialogs, and the user's manuals, saying that A/UX "defies the stereotype that Unix is difficult to use" and is "the easiest version of Unix to learn". Its list price of US$709 was higher than that of "much weaker" competing PC operating systems such as System 7, OS/2, MS-DOS, and Windows 3.1, but low compared to the then prevailing proprietary Unix licenses of more than US$2,000. The review found the system speed "acceptable but not great" even on the fastest Quadra 950, blaming not the software but the incomplete Unix optimization found in Apple's hardware. Though "a very good value", the system's price-performance ratio was judged as altogether uncompetitive against Sun's SPARCstation 2. The reviewers thought it unlikely for users "to want to buy Macs just to run A/UX" and would have awarded InfoWorld's top score if the OS was not proprietary to Macintosh hardware.[4]

Tony Bove of the Bove & Rhodes Report complained that "[f]or Unix super-users there is no compelling reason to buy Apple's Unix. For Apple A/UX has always been a way to sell Macs, not Unix; it's a check-off item for users."[14]


Vintage A/UX users had one central repository for most A/UX applications: an Internet server at NASA called “Jagubox”. It was administered by Jim Jagielski, who was also the editor of the A/UX FAQ. Although Jagubox has been decommissioned, some mirrors are still maintained.[when?][citation needed]

Because A/UX's hardware requirements include a memory management unit, the execution of A/UX within Macintosh emulation software was not possible until 2014's introduction of a particular Macintosh II emulator named Shoebill.[20][self-published source]

See also[edit]

  • macOS, Apple's newer Unix branded operating system (different code, but same Unix ideas plus older "mac" ideas).
  • PowerOpen Environment, an open standard for running a Unix-based operating system on the PowerPC computer architecture.
  • MachTen, Unix in the form of a Mac OS application.
  • MacMach, Unix providing experimental Mac OS compatibility as a Unix application.
  • Executor, a third party reverse engineered reimplementation of System 7 as a Unix application.
  • Macintosh Application Environment, a Mac OS application virtual machine for third party Unix systems.
  • Classic, classic Mac OS applications as a Unix virtual machine process.
  • Star Trek project, System 7 ported as a DOS application for IBM PC clones.
  • MkLinux, Apple-sponsored Linux on Macintosh hardware.


  1. ^ a b c d Pitta, Julie (15 February 1988). "A/UX ships following lengthy delay". Computerworld. p. 133.
  2. ^ Flynn, Laurie (7 March 1988). "Universities High on A/UX But Want More". InfoWorld. p. 31. Retrieved 19 June 2017.
  3. ^ "macOS version 10.12 Sierra on Intel-based Mac computers". The Open Group. Retrieved September 29, 2016.
  4. ^ a b c d e f Crabb, Don (10 August 1992). "Apple finally gets Unix right with A/UX 3.0". InfoWorld. pp. 68–69.
  5. ^ Betts, Mitch (8 August 1988). "Uncle Sam Salutes the Mac". Computerworld.
  6. ^ a b Ryan, Alan J. (15 August 1988). "Apple keen on Unix future". Computerworld.
  7. ^ Singh, Amit (February 2004). "Many Systems for Many Apples". Kernel Thread.
  8. ^ "A/UX and Compatible Macintoshes". Apple, Inc. August 1994.
  9. ^ a b Flynn, Laurie; Patton, Carole (22 February 1988). "Apple breaks into Unix market with A/UX". InfoWorld. p. 31.
  10. ^ Flynn, Laurie (22 February 1988). "Developers Eager to Display Programs Run Under A/UX". InfoWorld. p. 32.
  11. ^ Keefe, Patricia (2 March 1987). "Apple brackets Unix, Ethernet". Computerworld.
  12. ^ Mace, Scott; Patton, Carole (8 August 1988). "Apple to Support X Window in A/UX". InfoWorld.
  13. ^ a b Marshall, Martin (16 January 1989). "A/UX, Release 1.1 Supports X Window". InfoWorld. p. 31.
  14. ^ a b c Corcoran, Cate (4 November 1991). "Apple reveals plans for updated A/UX, PowerOpen Unix development alliance". InfoWorld. pp. 1, 115–116.
  15. ^ Gillooly, Caryn (13 April 1992). "Apple unveils secure A/UX for Macintosh networks". Network World. p. 13.
  16. ^ "Floodgap ANSwers: The AIX on ANS FAQ". What versions of AIX does the ANS support? Only 4.1.4 ( and and 4.1.5, and then only Apple-branded versions
  17. ^ "A/UX FAQ".
  18. ^ "The BYTE Awards". BYTE. January 1989. p. 327.
  19. ^ Crabb, Don (4 April 1988). "A/UX: This Operating System Is Far From Being "Unix for the Rest of Us"". InfoWorld.
  20. ^ "Shoebill, a Macintosh II emulator that runs A/UX".

External links[edit]