UNIX

UNIX (originally called Unics) was a multi-user Operating System and was a alternative to Multics. The Team around UNIX included Dennis Ritchie, Ken Thompson, Douglas McIllroy and Joseph Ossanna. The first version was completely written in PDP-7 Assembler.

Between 1972 and 1974 it was completely rewritten in the then newly developed programming language C (known as UNIX V4). UNIX was mainly distributed to Universities for the price of the media.

Main features

 * Multi-User (more than one user could be logon to the system)
 * Multi-Tasking (Tasks could be run in pseudo-parallel, each one giving a time-slice)
 * Hierarchical Filesystem (files could be stored in directories)
 * Powerful Shell (CLI-based user interface)
 * Pipes (redirect Standard Input/Output)
 * Filters (Utilities that tranform input)
 * Large-Set of Utilities
 * Included Software Development Tools (all tools required to develop own programs are included (Assembler, C-Compiler, Linker, ...))

History
In 1977, the first version of BSD, 1BSD, a project led by Bill Joy at the University of California, Berkeley, which based on UNIX V6 and V7, was distributed to interested persons on magnet tape. In 1978, the second version, 2BSD, was distributed. 3BSD was the first version which included the ability to address virtual memory.

The original UNIX developer also tried to make a 32-Bit version of UNIX for the VAX, but it didn't included the ability to address virtual memory. This version was called UNIX 32/V.

At the end of the 1970s, AT&T tried to commercialize UNIX, with the result of System III, later System V, which was the base for many commercial UNIX-based Systems.

Examples for modern UNIX-like OSes are FreeBSD, OpenBSD, NetBSD, Linux, macOS, HP-UX and Tru64 UNIX.