A/UX 3.0.1 with Finder, CommandShell and Netscape
A/UX 3.0.1 with Finder, CommandShell and Netscape
Developer Apple Computer
OS family UNIX System V
Working state Historic
Source model Closed source
Initial release February 1988 (February 1988)[1]
Latest release 3.1.1 / 1995 (1995)
Kernel type Monolithic kernel
License Proprietary

A/UX was Apple Computer’s implementation of the Unix operating system for some of their Macintosh computers. 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.

Described by InfoWorld as "an open systems solution with the Macintosh at its heart",[2] 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.[3][4]


  • Features 1
  • History 2
  • Reception 3
    • Legacy 3.1
  • See also 4
  • References 5
  • External links 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.[2]

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.

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 you to reformat third party SCSI drives in a way such that they can be used in other Macs of that era.[2]

A/UX runs only on 68k-based Macintoshes with a floating point unit (FPU) and a paged memory management unit (PMMU),[5] and even then only on select models. For example, the Quadra 840AV, Apple's fastest 68k Macintosh, cannot run A/UX.[6]


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][7] It was initially aimed at existing Unix shops, universities and VARs.[7] Third-party software announced with the system's first release includes the Ingres database, StatView, developer tools, and various productivity software packages.[1][8] The TCP/IP, AppleTalk and NFS implementations in the operating system were provided by UniSoft.[9] The product's first release ran less than 10% of the Macintosh application base, and could not 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.[10] X and POSIX support were in place as of A/UX 1.1, released 1989.[11]

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.[12]

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, intended to combine A/UX with aspects of IBM's AIX variant of Unix, and with the OSF/1 kernel from the Open Software Foundation. A/UX 3.0 serves as an "important migration path" thereto, making Unix and System 7 applications compliant with PowerOpen.[2] 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.[12]

In 1992, a C2-level secure version of A/UX was released.[13]

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.[14] With Steve Jobs's return to Apple as part of its 1996 acquisition of NeXT, Apple launched 1999's Mac OS X, based on the Unix-like NeXTSTEP operating system.

The final release of A/UX is version 3.1.1 of 1995.[15] Apple abandoned the A/UX platform completely by 1996.

Timeline of Macintosh operating systems
A graphical timeline of Macintosh models


Compared to contemporary workstations from other Unix vendors, the Macintosh hardware lacks features such as demand paging. The first two versions A/UX consequently suffer from poor performance,[11] and thus poor sales.[2] Users also complained about the amount of disk space it uses.[4] 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.[16]

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". With a "superior Finder GUI" and single-button point-and-click installer, the review finds it a very full-featured operating system that "defies the stereotype that Unix is difficult to use". Compared to other "much weaker" PC operating systems such as System 7, OS/2, MS-DOS, and Windows 3.1, A/UX's US$709 original list price was a lot higher but its Unix architecture gives it "excellent" memory management and "rock solid" multitasking capabilities which are "light-years ahead". The advanced documentation and the programming tools were an extra expense; but the year of personal tech support, the graphical help dialogs, and the user's manuals are said to make it "the easiest version of Unix to learn". The review finds the system speed "acceptable but not great" even on the fastest Quadra 950, which is not the fault of the software but of Apple's personal computer hardware having incomplete optimization for Unix. Though a new A/UX-bundled Macintosh was overall cheaper than a competing vendor's higher-end Unix-only bundle, and the A/UX software license alone was "a very good value" compared to the then prevailing proprietary Unix licenses of more than US$2,000, the system's price-performance ratio is judged as altogether uncompetitive against Sun's SPARCstation 2. Overall, A/UX 3.0 would have received InfoWorld's top score if the OS was not proprietary to Macintosh hardware, and users were thought to be "unlikely to want to buy Macs just to run A/UX".[2]

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."[12]


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.

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.[17]

See also

  • 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 (Mac OS X), 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. 
  2. ^ 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. 
  3. ^ Betts, Mitch (8 August 1988). "Uncle Sam Salutes the Mac". Computerworld. 
  4. ^ a b Ryan, Alan J. (15 August 1988). "Apple keen on Unix future". Computerworld. 
  5. ^ Singh, Amit (February 2004). "Many Systems for Many Apples". Kernel Thread. 
  6. ^ "A/UX and Compatible Macintoshes". Apple, Inc. August 1994. 
  7. ^ a b Flynn, Laurie; Patton, Carole (22 February 1988). "Apple breaks into Unix market with A/UX". InfoWorld. p. 31. 
  8. ^ Flynn, Laurie (22 February 1988). "Developers Eager to Display Programs Run Under A/UX". InfoWorld. p. 32. 
  9. ^ Keefe, Patricia (2 March 1987). "Apple brackets Unix, Ethernet". Computerworld. 
  10. ^ Mace, Scott; Patton, Carole (8 August 1988). "Apple to Support X Window in A/UX". InfoWorld. 
  11. ^ a b Marshall, Martin (16 January 1989). "A/UX, Release 1.1 Supports X Window". InfoWorld. p. 31. 
  12. ^ a b c Corcoran, Cate (4 November 1991). "Apple reveals plans for updated A/UX, PowerOpen Unix development alliance". InfoWorld. pp. 1, 115–116. 
  13. ^ Gillooly, Caryn (13 April 1992). "Apple unveils secure A/UX for Macintosh networks". Network World. p. 13. 
  14. ^ "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 
  15. ^ "A/UX FAQ". 
  16. ^ Crabb, Don (4 April 1988). """A/UX: This Operating System Is Far From Being "Unix for the Rest of Us. InfoWorld. 
  17. ^ "Shoebill, a Macintosh II emulator that runs A/UX". 

External links

  • Official A/UX FAQ
  • Unofficial A/UX FAQ: updates the official FAQ from the 1998 version
  • A/UX Installation Tutorial and General Info
  • A/UX at DMOZ