Because of a ``1956 consent decree, AT& was limited in the businesses that they could engage in and the patents they could licence..." [p. 4]RT:UNIX. This consent decree delayed the introduction of AT&'s first commercial release by a few years. This first official release finally occurred in 1982, and was called System III. This version did not include ``important Berkeley innovations, such as the C shell and screen editing capabilities" [p. 6]RT:UNIX.
The next version, System V, followed in 1983. This version did include utilities such as vi and curses from the BSD.
System V Release 2 was released in 1984, and System V Release 3 in 1987.
Finally, System V Release 4 was officially announced on Nov 1, 1989, and was released in 1990. This version combines System V Release 3, 4.3BSD, XENIX, SunOS and new features in one operating system.
Figure 1.1 offers a graphical view of the evolution of the UNIX operating system.
