From The Free On-line Dictionary of Computing (19 January 2023):
Berkeley Software Distribution
4.2BSD
4.3BSD
Berkeley 4.2
Berkeley Unix
BSD
BSD Unix
<operating system> (BSD) A family of Unix versions developed
by Bill Joy and others at the University of California at
Berkeley, originally for the DEC VAX and PDP-11
computers, and subsequently ported to almost all modern
general-purpose computers. BSD Unix incorporates paged
virtual memory, TCP/IP networking enhancements and many
other features.
BSD UNIX 4.0 was released on 1980-10-19. The BSD versions
(4.1, 4.2, and 4.3) and the commercial versions derived from
them (SunOS, ULTRIX, Mt. Xinu, Dynix) held the
technical lead in the Unix world until AT&T's successful
standardisation efforts after about 1986, and are still widely
popular.
See also Berzerkeley, USG Unix.
(2005-01-20)