A/UX is a very special Unix system.

Mixed from Uniplus,BSD System V,and SunOS.

It even supports different file systems like NFS via the sun vfs.

It has the system V FS ,STREAMS and supports TCP/IP and select()

and BSD signals.

It contains mixup code so that programs can use the GUI routines in the ROM.

The only release where I have kernel source code runs only on

the original Mac II and does not support all the hardware and periphals.