In 1979, Bill Joy, Ozalp Babauglu, and a host of other graduate students at the University of California, Berkeley added virtual memory and many other enhancements, such as vi and csh, to Bell Labs UNIX/32V, resulting in a sequence of Berkeley Software Distributions (3BSD, 4BSD, 4.xBSD) that became the most widely used UNIX variant in the early 1980s. ARPA contracted with Berkeley to add TCP/IP to 4.2BSD, which became the backbone of the fledgling Internet in 1983.
Berkeley’s VAX 11/780, ucbvax, with .5 MB of RAM and a 1 MIPS 32 bit processor, was connected by dialup UUCP to other UNIX hosts, and by 9600 bps serial lines to the ARPANET. It became a gateway for e-mail between the two networks.
4.2BSD UNIX became the SunOS operating system used by fledgling start-up Sun Microsystems. Berkeley’s socket-based TCP/IP stack was used in most TCP/IP implementations.