SCO Unix

SCO OpenServer, previously SCO UNIX and SCO Open Desktop (SCO ODT), is a closed source version of the Unix computer operating system developed by Santa Cruz Operation (SCO) and now maintained by the SCO Group.

BSD (Free and Open)

FreeBSD® is an advanced operating system for x86 compatible (including Pentium® and Athlon™), amd64 compatible (including Opteron™, Athlon™64, and EM64T), UltraSPARC®, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX® developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.

AT&T Unix

As is obvious from its name, the AT&T UNIX PC uses the operating system UNIX. Full System V UNIX is supported, although the system comes "unbundled" - the essential commands and utilities for running and maintaing the system are included, but special purpose utilities - such as the C compiler, - are optional extras.UNIX is the ideal operating system for a powerful machine like this - it is a multiuser, multitasking operating system. This means that more than one user can use the system at one time (with extra terminals), and that each user may run a number of processes, or tasks, simultaneously. It is also the nearest thing to a "universal" operating system around, and runs on computers rangin in size from portable personal computers to room-filling mainframes, and in power from micros to the Cray-2 supercomputer. The fact that UNIX originated in AT&T's Bell Laboratories also says something about how well supported this software is likely to be on this hardware.