Brian Kernighan, companion of Thomson, ironically called UNICS. UNIX passes to a PDP-11 (1970) machine. Ritchie designed and wrote a compiler for language C. Thomson and Ritchie rewrite UNIX in C, breaking the tradition of operating systems written in assembler (1973). This increases the portability of the system into other machines. Thomson and Ritchie received the Turing Award for a memorable article on UNIX written in 1974. By the same author: Roubini Global Economics. UNIX is adopted in universities, because it is an open system that provides all the code source (1974). BSD and System V; the POSIX standard.
The dismemberment of AT & T (1984) allows this company to enter the market of computers, and produced the first commercial version of UNIX system III, which is soon replaced by the System V versions 2, 3 and 4. UC Berkeley produced an improved version for the PDP-11, called 1BSD; they were then the 3BSD, and then 4BSD, which incorporated the TCP/IP networking protocol. The POSIX group studied and proposed a standard for UNIX, called 1003.1, which defines a set of procedures for library that any UNIX compliant system must provide. This solved the dispute between System V and BSD. OSF, Open Software Foundation, integrated by IBM, DEC, HP, and others to deal with AT & T.
creates a UNIX with more features than the POSIX standard forms. Current versions of UNIX. AT & T, to confront OSF, creates UI, UNIX International, along with other companies; create another extended POSIX UNIX. IBM creates its own variant of UNIX called AIX. The confusion of versions continues. arise the UNIX versions of FreeBSD and Linux public domain, that are distributed without cost. Linux is developed by a multitude of people and teams over the Internet. FreeBSD is developed by a closed working group.