A/UX (from Apple Unix) was Apple Computer’s implementation of the Unix operating system for some of their Macintosh computers. A/UX required a 68k-based Macintosh with an FPU and a paged memory management unit (PMMU), and various versions ran on the Macintosh II, SE/30, Quadra and Centris series of machines. A/UX was first released in 1988, with the final version (3.1.1) released in 1995. No Macintosh emulation software currently supports A/UX as a hosted operating system.
The operating system was based on UNIX System V Release 2.2. It included some additional features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It was POSIX and System V Interface Definition (SVID) compliant and 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 existed.