History of Operating Systems - Minicomputers and The Rise of Unix

Minicomputers and The Rise of Unix

Digital Equipment Corporation created several operating systems for its 16-bit PDP-11 machines, including the simple RT-11 system, the time-sharing RSTS operating systems, and the RSX-11 family of real-time operating systems, as well as the VMS system for the 32-bit VAX machines.

The Unix operating system was developed at AT&T Bell Laboratories in the late 1960s, originally for the PDP-7, and later for the PDP-11. Because it was essentially free in early editions, easily obtainable, and easily modified, it achieved wide acceptance. It also became a requirement within the Bell systems operating companies. Since it was written in the C language, when that language was ported to a new machine architecture, Unix was also able to be ported. This portability permitted it to become the choice for a second generation of minicomputers and the first generation of workstations. By widespread use it exemplified the idea of an operating system that was conceptually the same across various hardware platforms. It still was owned by AT&T Corporation and that limited its use to groups or corporations who could afford to license it. It became one of the roots of the free software and open source movements.

Another system which evolved in this time frame was the Pick operating system. The Pick system was developed and sold by Microdata Corporation who created the precursors of the system. The system is an example of a system which started as a database application support program and graduated to system work.