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Note icon color.pngWikipedia has more information about A/UX.

A/UX (from Apple UNIX) was Apple Computer's implementation of the UNIX operating system for some of their Macintosh computers. The later versions of A/UX ran on the Macintosh II, Quadra and Centris series of machines. A/UX was first released in 1988, with the final version (3.1.1) released in 1995. A/UX required a 68k-based Macintosh with an FPU and a paged PMMU.

The operating system was based on UNIX System V Release 2.2, with some additional features from System V Releases 3 and 4, and 4.2 and 4.3 BSD. It was POSIX and SVID compliant, though conformed to versions of the standards which are no longer state of the art. It included TCP/IP networking from version 2 onward. There were rumors of a later version using OSF/1 as its primary code base, but this system was never released to the public – if it ever existed.


A/UX 3.x provided a GUI with the familiar Finder windows, menus, and controls. The A/UX Finder was 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 UNIX kernel and file systems. A/UX 3.x also included a CommandShell terminal program, which offered a CLI to the underlying UNIX system, a feature which had never been available on Macintosh computers running the classic Mac OS Finder. An X Window System server application (called MacX) with a terminal program could also be used to interface with the system and run X Window applications directly in the Finder. Alternatively, the user could choose to run a full X11R4 session without the Finder.

By including a compatibility layer, A/UX could run Macintosh System 7.0.1, UNIX, and "hybrid" applications. A hybrid application used both Macintosh and UNIX system functions: for example, a Macintosh application which called UNIX system functions, or a UNIX application which called Macintosh Toolbox (e.g. QuickDraw) functions. The compatibility layer used some existing Toolbox functions in the computer's ROM, while other function calls were translated into native UNIX system calls.

A/UX included a utility called Commando (similar to a tool of the same name included with MPW) to assist users with entering UNIX commands. Opening a UNIX executable file from the Finder would open a dialog box that allowed 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 was intended to ease the learning curve for users new to UNIX, and decrease the user's reliance on the UNIX manual.

Compatible machines

The following machines are capable of running A/UX 3, and are listed in order of general desirability.

Machines capable of running A/UX, listed in general order of desirability
Model CPU MHz CPU type Form Series RAM type Max RAM (Apple) Max RAM (actual) PDS slots Nubus slots MacOS A/UX FPU MSRP Notes
Quadra 800 33 MHz Motorola MC68040 tower Quadra 72-pin SIMM 136 MiB 040 {{{slots-nubus}}} System 7.1 - Mac OS 8.1 3.0.1 - 3.1.1 $4699 (US)
Quadra 650 33 MHz Motorola MC68040 desktop Quadra 72-pin SIMM 138 MiB 040 3 System 7.1 — Mac OS 8.1 3.0.1 — 3.1.1 $2399 (US)
Quadra 950 33 MHz Motorola MC68040 tower Quadra 30-pin SIMM 64 MiB 256 MiB 040 5 System 7.0.1 - Mac OS 8.1 $8500 (US)
Centris 650 25 MHz Motorola MC68040 desktop Centris 72-pin SIMM 138 MiB 040 3 System 7.1 — Mac OS 8.1 3.0.1 — 3.1.1 $2699 (US) [1]
Quadra 900 25 MHz Motorola MC68040 tower Quadra 30-pin SIMM 64 MiB 256 MiB 040 5 System 7.0.1 - Mac OS 8.1 3.0 - 3.1.1 $7200 (US)
Quadra 610 25 MHz Motorola MC68040 desktop Quadra 72-pin SIMM 68 MiB 040 1 (with PDS adapter) System 7.1 - Mac OS 8.1 $1439 (US)
Quadra 700 25 MHz Motorola MC68040 tower Quadra 30-pin SIMM 20 MiB 68 MiB 040 2 System 7.0.1 - Mac OS 8.1 3.0 - 3.1.1 $6000 (US)
Centris 610 20 MHz Motorola MC68LC040 desktop Centris 72-pin SIMM 68 MiB 040 1 (with PDS adapter) System 7.1 - Mac OS 8.1 $1859 [1]
IIsi 20 MHz Motorola MC68030 desktop Macintosh II 30-pin SIMM 65 MiB 030 System 6.0.6 - Mac OS 7.6.1 2.0.1 - 3.1.1 $3769 (US) [2][3]
II 16 MHz Motorola MC68020 desktop Macintosh II 30-pin SIMM 20 MiB (68 MiB with FDHD upgrade) 6 System 4.1/Finder 5.5 - System 7.5.5 Motorola MC68881 (optional) $3900 or $5500 with HD (US) [2][4]
SE/30 16 MHz Motorola MC68030 all-in-one Macintosh 30-pin SIMM 64 MiB 128 MiB 030 System 6.0.3 - 7.5.5 1.1.1 - 3.1.1 Motorola 68882 $4400 or $4900 with HD (US)


Unfortunately for Apple and for A/UX users, the UNIX niche was a costly business in the early 1990s. Apple never ported A/UX to PowerPC Macintoshes (though A/UX 4.0 was rumored to have been an OSF/1 adaptation), and the company all but abandoned it by 1996, preferring to use a slightly modified version of IBM's AIX system on their mid-'90s Apple Network Servers. After Steve Jobs returned to Apple, another UNIX-like operating system was introduced in the form of Mac OS X, but it had very little in common with A/UX, seeing that it was based on NeXTSTEP.

A/UX users had one central source for most A/UX applications: a server at NASA called "Jagubox" administered by Jim Jagielski, who was also the editor of the A/UX FAQ. Although Jagubox is down, some mirrors are still maintained. Aside from a few isolated servers still running it, A/UX is essentially extinct, and is considered to be abandonware.


  1. 1.0 1.1 1.2 1.3 Possibly requires replacement of 68LC040 with full 68040 CPU.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Lacks internal CD-ROM for installation.
  3. 3.0 3.1 Requires addition of 68882 FPU.
  4. 4.0 4.1 4.2 4.3 4.4 Should not run version 3.1.1 due to stability issues.

External links