Recently, I have been successful in making A/UX boot and run stable on my vintage Macintosh emulator; Snow. A/UX was Apple’s version of UNIX that ran on the 68k-based series Macs. It required a Memory Management Unit to achieve process isolation; either the optional 68851 PMMU on the original 68020-based Macintosh II or the integrated MMU in the 68030- and 68040-based machines. It also required an FPU; making it only run on the higher end machines such as the Macintosh II series and later the Quadra, but the LC was out of luck. A/UX Penelope is a nice resource on A/UX compatibility info.