A/UX (Apple UNIX for m68k macs) version 3.0.1 + 3.1 update

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 as well as the SE/30. 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 memory management unit (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 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 even existed.