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BERKELEY SOFTWARE DISTRIBUTION (BSD) is a Unix
Unix
operating system derivative developed and distributed by the Computer Systems Research Group (CSRG) of the University of California, Berkeley
University of California, Berkeley
, from 1977 to 1995. Today the term "BSD" is often used non-specifically to refer to any of the BSD descendants which together form a branch of the family of Unix-like
Unix-like
operating systems. Operating systems derived from the original BSD code remain actively developed and widely used.

Historically, BSD has been considered a branch of Unix, BERKELEY UNIX, because it shared the initial codebase and design with the original AT"> Simplified evolution of Unix
Unix
systems. Not shown are Junos , PlayStation 3 system software and other proprietary forks.

The earliest distributions of Unix
Unix
from Bell Labs
Bell Labs
in the 1970s included the source code to the operating system, allowing researchers at universities to modify and extend Unix. The operating system arrived at Berkeley in 1974, at the request of computer science professor Bob Fabry who had been on the program committee for the Symposium on Operating Systems Principles where Unix
Unix
was first presented. A PDP-11/45 was bought to run the system, but for budgetary reasons, this machine was shared with the mathematics and statistics groups at Berkeley, who used RSTS , so that Unix
Unix
only ran on the machine eight hours per day (sometimes during the day, sometimes during the night). A larger PDP-11/70
PDP-11/70
was installed at Berkeley the following year, using money from the Ingres database project.

Also in 1975, Ken Thompson
Ken Thompson
took a sabbatical from Bell Labs
Bell Labs
and came to Berkeley as a visiting professor. He helped to install Version 6 Unix
Unix
and started working on a Pascal implementation for the system. Graduate students Chuck Haley and Bill Joy improved Thompson's Pascal and implemented an improved text editor, ex . Other universities became interested in the software at Berkeley, and so in 1977 Joy started compiling the first Berkeley Software Distribution (1BSD), which was released on March 9, 1978. 1BSD was an add-on to Version 6 Unix
Unix
rather than a complete operating system in its own right. Some thirty copies were sent out.

The Second Berkeley Software Distribution (2BSD), released in May 1979, included updated versions of the 1BSD software as well as two new programs by Joy that persist on Unix
Unix
systems to this day: the vi text editor (a visual version of ex ) and the C shell
C shell
. Some 75 copies of 2BSD were sent out by Bill Joy. The VAX-11/780 , a typical minicomputer used for early BSD timesharing systems

A VAX
VAX
computer was installed at Berkeley in 1978, but the port of Unix
Unix
to the VAX
VAX
architecture, UNIX/32V , did not take advantage of the VAX's virtual memory capabilities. The kernel of 32V was largely rewritten by Berkeley students to include a virtual memory implementation, and a complete operating system including the new kernel, ports of the 2BSD utilities to the VAX, and the utilities from 32V was released as 3BSD at the end of 1979. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX (for Virtual Memory Unix), and BSD kernel images were normally called /vmunix until 4.4BSD. "4.3 BSD UNIX" from the University of Wisconsin
University of Wisconsin
circa 1987. System startup and login.

After 4.3BSD was released in June 1986, it was determined that BSD would move away from the aging VAX
VAX
platform. The Power 6/32 platform (codenamed "Tahoe") developed by Computer Consoles Inc. seemed promising at the time, but was abandoned by its developers shortly thereafter. Nonetheless, the 4.3BSD-TAHOE port (June 1988) proved valuable, as it led to a separation of machine-dependent and machine-independent code in BSD which would improve the system's future portability.

Apart from portability, the CSRG worked on an implementation of the OSI network protocol stack, improvements to the kernel virtual memory system and (with Van Jacobson of LBL ) new TCP/IP algorithms to accommodate the growth of the Internet.

Until then, all versions of BSD incorporated proprietary AT&T
AT&T
Unix code and were, therefore, subject to an AT&T
AT&T
software license. Source code licenses had become very expensive and several outside parties had expressed interest in a separate release of the networking code, which had been developed entirely outside AT&T
AT&T
and would not be subject to the licensing requirement. This led to NETWORKING RELEASE 1 (NET/1), which was made available to non-licensees of AT&T
AT&T
code and was freely redistributable under the terms of the BSD license . It was released in June 1989.

After Net/1, BSD developer Keith Bostic proposed that more non-AT&T sections of the BSD system be released under the same license as Net/1. To this end, he started a project to reimplement most of the standard Unix
Unix
utilities without using the AT&T
AT&T
code. Within eighteen months, all of the AT&T
AT&T
utilities had been replaced, and it was determined that only a few AT&T
AT&T
files remained in the kernel. These files were removed, and the result was the June 1991 release of Networking Release 2 (Net/2), a nearly complete operating system that was freely distributable.

Net/2 was the basis for two separate ports of BSD to the Intel 80386 architecture: the free 386BSD
386BSD
by William Jolitz and the proprietary BSD/386 (later renamed BSD/OS) by Berkeley Software Design (BSDi). 386BSD
386BSD
itself was short-lived, but became the initial code base of the NetBSD and FreeBSD projects that were started shortly thereafter.

BSDi soon found itself in legal trouble with AT programmers and technical people tended to line up with Berkeley and BSD, more business-oriented types with AT"> 4.3 BSD from the University of Wisconsin . Displaying the man page for Franz Lisp
Franz Lisp
Tape for SunOS
SunOS
4.1.1, a 4.3BSD derivative Sony NEWS
Sony NEWS
workstation running the BSD-based NEWS-OS operating system

Berkeley's Unix
Unix
was the first Unix
Unix
to include libraries supporting the Internet Protocol
Internet Protocol
stacks: Berkeley sockets . A Unix
Unix
implementation of IP's predecessor, the ARPAnet's NCP , with FTP and Telnet clients, had been produced at U. Illinois in 1975, and was available at Berkeley. However, the memory scarcity on the PDP-11
PDP-11
forced a complicated design and performance problems.

By integrating sockets with the Unix
Unix
operating system's file descriptors , it became almost as easy to read and write data across a network as it was to access a disk. The AT&T
AT&T
laboratory eventually released their own STREAMS
STREAMS
library, which incorporated much of the same functionality in a software stack with a different architecture, but the wide distribution of the existing sockets library reduced the impact of the new API . Early versions of BSD were used to form Sun Microsystems ' SunOS
SunOS
, founding the first wave of popular Unix workstations.

BINARY COMPATIBILITY

BSD operating systems can run much native software of several other operating systems on the same architecture , using a binary compatibility layer . Much simpler and faster than emulation , this allows, for instance, applications intended for Linux
Linux
to be run at effectively full speed. This makes BSDs not only suitable for server environments, but also for workstation ones, given the increasing availability of commercial or closed-source software for Linux
Linux
only. This also allows administrators to migrate legacy commercial applications, which may have only supported commercial Unix
Unix
variants, to a more modern operating system, retaining the functionality of such applications until they can be replaced by a better alternative.

STANDARDS ADHERENCE

Current BSD operating system variants support many of the common IEEE , ANSI , ISO , and POSIX standards, while retaining most of the traditional BSD behavior. Like AT"> Bar chart
Bar chart
showing the proportion of users of each BSD variant from a BSD usage survey in 2005. Each participant was permitted to indicate multiple BSD variants See also: Comparison of BSD operating systems
Comparison of BSD operating systems

BSD has been the base of a large number of operating systems. Most notable among these today are perhaps the major open source BSDs: FreeBSD , NetBSD and OpenBSD
OpenBSD
, which are all derived from 386BSD
386BSD
and 4.4BSD
4.4BSD
-Lite by various routes. Both NetBSD and FreeBSD started life in 1993, initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite code base. OpenBSD
OpenBSD
was forked in 1995 from NetBSD. The three most notable descendants in current use—sometimes known as the BSDs—have themselves spawned a number of children, including DragonFly BSD , FreeSBIE , MirOS BSD , DesktopBSD , and TrueOS . They are targeted at an array of systems for different purposes and are common in government facilities, universities and in commercial use. A number of commercial operating systems are also partly or wholly based on BSD or its descendants, including Sun\'s SunOS
SunOS
and Apple Inc.
Apple Inc.
's macOS .

Most of the current BSD operating systems are open source and available for download, free of charge, under the BSD License , the most notable exception being macOS . They also generally use a monolithic kernel architecture, apart from macOS and DragonFly BSD which feature hybrid kernels . The various open source BSD projects generally develop the kernel and userland programs and libraries together, the source code being managed using a single central source repository.

In the past, BSD was also used as a basis for several proprietary versions of Unix, such as Sun 's SunOS
SunOS
, Sequent 's Dynix
Dynix
, NeXT
NeXT
's NeXTSTEP , DEC 's Ultrix and OSF/1
OSF/1
AXP (now Tru64 UNIX
Tru64 UNIX
). Parts of NeXT's software became the foundation for macOS , among the most commercially successful BSD variants in the general market.

SEE ALSO

* Free software
Free software
portal

* BSD Daemon * BSD licenses * Comparison of BSD operating systems
Comparison of BSD operating systems
* List of BSD operating systems

REFERENCES

* ^ A B C D Salus, Peter H. (2005). "Chapter 7. BSD and the CSRG". The Daemon, the Gnu and the Penguin. Groklaw
Groklaw
. * ^ Salus (1994), p. 142 * ^ Toomey, Warren. "Details of the PUPS archives". tuhs.org. The Unix
Unix
Heritage Society. Retrieved October 6, 2010. * ^ M.K. McKusick, M.J. Karels, Keith Sklower, Kevin Fall, Marc Teitelbaum and Keith Bostic (1989). Current Research by The Computer Systems Research Group of Berkeley. Proc. European Unix
Unix
Users Group. * ^ Eric S. Raymond. "The Art of Unix
Unix
Programming: Origins and History of Unix, 1969–1995". Retrieved 2014-07-18. * ^ http://www.kuro5hin.org/?op=displaystory;sid=2001/6/19/05641/7357 * ^ "BSD Code in Windows". everything2.com. March 20, 2001. Retrieved 2009-01-20. * ^ Dennis Ritchie (October 26, 2000). "alt.folklore.computers: BSD (Dennis Ritchie)". Retrieved July 3, 2014. * ^ Raymond, Eric S. The Art of Unix
Unix
Programming. 2003. p. 38 * ^ Curry, David. Using C on the UNIX System: A Guide to System Programming. 1989. pp. 2–3 * ^ G. L. Chesson (1976). The network Unix
Unix
system. Proc. 5th ACM Symp. on Operating Systems Principles. * ^ RFC 681 . * ^ Quarterman, John S.; Silberschatz, Abraham; Peterson, James L. (December 1985). "4.2BSD and 4.3BSD as examples of the Unix
Unix
system". Computing Surveys. 17 (4): 379–418. CiteSeerX 10.1.1.117.9743  . doi :10.1145/6041.6043 . * ^ "BSD Usage Survey" (PDF). BSD Certification Group. October 31, 2005. Archived from the original (PDF) on 2012-01-15. Retrieved 2009-01-20.

BIBLIOGRAPHY

* Marshall K. McKusick, Keith Bostic, Michael J. Karels, John S. Quartermain, The Design and Implementation of the 4.4BSD
4.4BSD
Operating System (Addison Wesley, 1996; ISBN 978-0-201-54979-9 ) * Marshall K. McKusick, George V. Neville-Neil, The Design and Implementation of the FreeBSD Operating System (Addison Wesley, August 2, 2004; ISBN 978-0-201-70245-3 ) * Samuel J. Leffler, Marshall K. McKusick, Michael J. Karels, John S. Quarterman , The Design and Implementation of the 4.3BSD UNIX Operating System (Addison Wesley, November 1989; ISBN 978-0-201-06196-3 ) * McKusick, Marshall Kirk (1999). "Twenty Years of Berkeley Unix
Unix
– From AT Ockman, Sam; Stone, Mark. Open Sources