A/UX

A/UX is Apple Inc.'s implementation of the Unix operating system for some of their Apple Macintosh computers, the latest versions running on the Mac 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 requires a Motorola 680x0 Mac with an floating-point unit (FPU) and a paged memory management unit (PMMU).

The system is based on System V.2.2 with features of V.3 and V.4 and BSD 4.2 and 4.3. It is POSIX and System V Interface Definition (SVID) compliant.

A/UX 3.x has Macintosh System 7.0.1 running on top of it, so the user is virtually using a normal Macintosh, with the familiar Finder graphical user interface and applications. An X Window System server application or a terminal program may be used to interface with the underlying Unix-system. Alternatively the user may choose to run a full X11R4 session, without the Finder.

By including a compatibility layer, A/UX could run Macintosh System 7 applications, Unix applications, and "hybrid" applications. A hybrid application could be 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.

Unfortunately for A/UX fans, the Unix niche was a costly business in the early 1990s. A/UX was never ported to PowerPC Macintoshes, and Apple all but abandoned it by 1996. As Steve Jobs returned to Apple later on, the future of Mac OS would end up truer to NeXTSTEP than to the old Mac or traditional Unix.

A/UX users had one central source for most A/UX applications, a server at NASA called "Jagubox." Although Jagubox is down, some mirrors are still maintained.

Aside from a few isolated servers, this OS is essentially extinct.