The History of the

Berkeley Software Distribution The Berkeley Software Distribution or Berkeley Standard Distribution (BSD) is a discontinued operating system based on Research Unix, developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Ber ...

begins in the 1970s.

1BSD (PDP-11)

The earliest distributions of Unix from

Bell Labs Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...

in the 1970s included the

source code In computing, source code, or simply code, is any collection of code, with or without comment (computer programming), comments, written using a human-readable programming language, usually as plain text. The source code of a Computer program, p ...

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 Robert Samuel Fabry, as a student at the University of Chicago worked on COMIT II and MADBUG, an interactive debugger for MAD both on CTSS. Later while a computer science professor at the University of California, Berkeley, conceived of the id ...

who had been on the program committee for the

Symposium on Operating Systems Principles In ancient Greece, the symposium ( grc-gre, συμπόσιον ''symposion'' or ''symposio'', from συμπίνειν ''sympinein'', "to drink together") was a part of a banquet that took place after the meal, when drinking for pleasure was acc ...

where 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 only ran on the machine eight hours per day (sometimes during the day, sometimes during the night). A larger PDP-11/70 was installed at Berkeley the following year, using money from the

Ingres Jean-Auguste-Dominique Ingres ( , ; 29 August 1780 – 14 January 1867) was a French Neoclassical painter. Ingres was profoundly influenced by past artistic traditions and aspired to become the guardian of academic orthodoxy against the a ...

database project. Also in 1975,

Ken Thompson Kenneth Lane Thompson (born February 4, 1943) is an American pioneer of computer science. Thompson worked at Bell Labs for most of his career where he designed and implemented the original Unix operating system. He also invented the B programmi ...

took a

sabbatical A sabbatical (from the Hebrew: (i.e., Sabbath); in Latin ; Greek: ) is a rest or break from work. The concept of the sabbatical is based on the Biblical practice of ''shmita'' (sabbatical year), which is related to agriculture. According to ...

from Bell Labs and came to Berkeley as a visiting professor. He helped to install

Version 6 Unix Sixth Edition Unix, also called Version 6 Unix or just V6, was the first version of the Unix operating system to see wide release outside Bell Labs. It was released in May 1975 and, like its direct predecessor, targeted the DEC PDP-11 family of m ...

and started working on a Pascal implementation for the system. Graduate students Chuck Haley and

Bill Joy William Nelson Joy (born November 8, 1954) is an American computer engineer and venture capitalist. He co-founded Sun Microsystems in 1982 along with Scott McNealy, Vinod Khosla, and Andy Bechtolsheim, and served as Chief Scientist and CTO a ...

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 rather than a complete operating system in its own right. Some thirty copies were sent out.

2BSD (PDP-11)

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 systems to this day: the vi text editor (a

visual The visual system comprises the sensory organ (the eye) and parts of the central nervous system (the retina containing photoreceptor cells, the optic nerve, the optic tract and the visual cortex) which gives organisms the sense of sight ...

version of ex) and the

C shell The C shell (csh or the improved version, tcsh) is a Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s. It has been widely distributed, beginning with the 2BSD release of the B ...

. Some 75 copies of 2BSD were sent out by Bill Joy. A further feature was a networking package called

Berknet The Berkeley Network, or Berknet, was an early wide area network, developed at the University of California, Berkeley in 1978, primarily by Eric Schmidt as part of his master's thesis work. The network continuously connected about a dozen computers ...

, developed by

Eric Schmidt Eric Emerson Schmidt (born April 27, 1955) is an American businessman and software engineer known for being the CEO of Google from 2001 to 2011, executive chairman of Google from 2011 to 2015, executive chairman of Alphabet Inc. from 2015 to 2 ...

as part of his

master's thesis A thesis ( : theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144 ...

work, that could connect up to twenty-six computers and provided email and file transfer. After 3BSD (see below) had come out for the

VAX VAX (an acronym for Virtual Address eXtension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The V ...

line of computers, new releases of 2BSD for the PDP-11 were still issued and distributed through USENIX; for example, 1982's 2.8.1BSD included a collection of fixes for performance problems in

Version 7 Unix Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercia ...

, and later releases contained ports of changes from the VAX-based releases of BSD back to the PDP-11 architecture. 2.9BSD from 1983 included code from 4.1cBSD, and was the first release that was a full OS (a modified V7 Unix) rather than a set of applications and patches. The most recent release, 2.11BSD, was first issued in 1991. In the 21st Century, maintenance updates from volunteers continued: patch #473 was released on January 25, 2022.

3BSD

A VAX computer was installed at Berkeley in 1978, but the

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as ...

of Unix to the VAX architecture,

UNIX/32V UNIX/32V is an early version of the Unix operating system from Bell Laboratories, released in June 1979. 32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture. Overview Before 32V, Unix had primarily run on DEC P ...

, did not take advantage of the VAX's

virtual memory In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very ...

capabilities. The

kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine lea ...

of 32V was largely rewritten by Berkeley graduate student

Özalp Babaoğlu Ozalp Babaoğlu (born August 10, 1955 in Ankara, Turkey), is a Turkish computer scientist. He is currently professor of computer science at the University of Bologna, Italy. He received a Ph.D. in 1981 from the University of California at Berke ...

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. The success of 3BSD was a major factor in the

Defense Advanced Research Projects Agency The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Adv ...

's (DARPA) decision to fund Berkeley's

Computer Systems Research Group The Computer Systems Research Group (CSRG) was a research group at the University of California, Berkeley that was dedicated to enhancing AT&T Unix operating system and funded by Defense Advanced Research Projects Agency. History Professor B ...

(CSRG), which would develop a standard Unix platform for future DARPA research in the

VLSI Project The VLSI Project was a DARPA-program initiated by Robert Kahn in 1978 that provided research funding to a wide variety of university-based teams in an effort to improve the state of the art in microprocessor design, then known as Very Large Scale ...

4BSD

4BSD (November 1980) offered a number of enhancements over 3BSD, notably job control in the previously released csh,

delivermail The ancestor of sendmail, delivermail, also by Eric Allman, is a mail transport agent that used the FTP protocol on the early ARPANET to transmit e-mail to the recipient. Due to deficiencies in using FTP to send e-mail, a new protocol was created ...

(the antecedent of

sendmail Sendmail is a general purpose internetwork email routing facility that supports many kinds of mail-transfer and delivery methods, including the Simple Mail Transfer Protocol (SMTP) used for email transport over the Internet. A descendant of the ...

), "reliable" signals, and the

Curses A curse (also called an imprecation, malediction, execration, malison, anathema, or commination) is any expressed wish that some form of adversity or misfortune will befall or attach to one or more persons, a place, or an object. In particular, ...

programming library. In a 1985 review of BSD releases,

John Quarterman John S. Quarterman (born April 27, 1954) is an American author and longtime Internet participant. He wrote one of the classic books about networking prior to the commercialization of the Internet. He has also written about risk management. Bio ...

''et al.'', wrote:

4.1BSD

4.1BSD (June 1981) was a response to criticisms of BSD's performance relative to the dominant VAX operating system, VMS. The 4.1BSD kernel was systematically tuned up by

until it could perform as well as VMS on several benchmarks. The release would have been called ''5BSD'', but after objections from

AT&T AT&T Inc. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile tel ...

the name was changed; AT&T feared confusion with

UNIX System V Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, an ...

4.2BSD

4.2BSD (August 1983) would take over two years to implement and contained several major overhauls. Before its official release came three intermediate versions: 4.1a from April 1982 incorporated a modified version of BBN's preliminary

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

implementation; 4.1b from June 1982 included the new

Berkeley Fast File System The Unix file system (UFS) is a family of file systems supported by many Unix and Unix-like operating systems. It is a distant descendant of the original filesystem used by Version 7 Unix. Design A UFS volume is composed of the followin ...

, implemented by

Marshall Kirk McKusick Marshall Kirk McKusick (born January 19, 1954) is a computer scientist, known for his extensive work on BSD UNIX, from the 1980s to FreeBSD in the present day. He was president of the USENIX Association from 1990 to 1992 and again from 2002 to ...

; and 4.1c in April 1983 was an interim release during the last few months of 4.2BSD's development. Back at Bell Labs, 4.1cBSD became the basis of the 8th Edition of

Research Unix The term "Research Unix" refers to early versions of the Unix operating system for DEC PDP-7, PDP-11, VAX and Interdata 7/32 and 8/32 computers, developed in the Bell Labs Computing Sciences Research Center (CSRC). History The term ''Resear ...

, and a commercially supported version was available from

mtXinu mt Xinu (from the letters in "Unix™", reversed) was a software company founded in 1983 that produced two operating systems. Its slogan "We know Unix™ backwards and forwards" was an allusion to the company's name and abilities. mt Xinu ...

. To guide the design of 4.2BSD,

Duane Adams Duane may refer to: * Duane (given name) * Duane (surname) * Duane, New York, a US town * the title character of ''Duane Hopwood'', a 2005 film featured in the Sundance Film Festival * Duane Adelier, a main character of ''Unsounded'', a 2012 fantas ...

DARPA The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the Ad ...

formed a "steering committee" consisting of

and

Sam Leffler Samuel J Leffler is a computer scientist, known for his extensive work on BSD, from the 1980s to FreeBSD in the present day. Among other projects, he created FlexFAX, LibTIFF, and the FreeBSD Wireless Device Drivers. The ''Design and Implem ...

from UCB,

Alan Nemeth Alan may refer to: People *Alan (surname), an English and Turkish surname *Alan (given name), an English given name ** List of people with given name Alan ''Following are people commonly referred to solely by "Alan" or by a homonymous name.'' * ...

and

Rob Gurwitz Rob or ROB may refer to: Places * Rob, Velike Lašče, a settlement in Slovenia * Roberts International Airport (IATA code ROB), in Monrovia, Liberia People * Rob (given name), a given name or nickname, e.g., for Robert(o), Robin/Robyn * Rob ...

from BBN, Dennis Ritchie from

Keith Lantz Keith may refer to: People and fictional characters * Keith (given name) Keith is a given name of Gaelic origin. It means "wood" or "from the battleground" and shares the same derivation as Clan Keith. The surname derives from a toponym, Keit ...

from

Stanford Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

, Rick Rashid from

Carnegie Mellon Carnegie may refer to: People * Carnegie (surname), including a list of people with the name * Clan Carnegie, a lowland Scottish clan Institutions Named for Andrew Carnegie *Carnegie Building (Troy, New York), on the campus of Rensselaer Polyt ...

Bert Halstead Bert or BERT may refer to: Persons, characters, or animals known as Bert *Bert (name), commonly an abbreviated forename and sometimes a surname *Bert, a character in the poem "Bert the Wombat" by The Wiggles; from their 1992 album Here Comes a Son ...

from

MIT The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the ...

, Dan Lynch from

ISI ISI or Isi may refer to: Organizations * Intercollegiate Studies Institute, a classical conservative organization focusing on college students * Ice Skating Institute, a trade association for ice rinks * Indian Standards Institute, former name of ...

, and

Gerald J. Popek Gerald John "Jerry" Popek (September 22, 1946 – July 20, 2008) was an American computer scientist, known for his research on operating systems and virtualization. With Robert P. Goldberg he proposed the Popek and Goldberg virtualization require ...

UCLA The University of California, Los Angeles (UCLA) is a public university, public Land-grant university, land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a Normal school, teachers colle ...

. The committee met from April 1981 to June 1983. Apart from the Fast File System, several features from outside contributors were accepted, including disk quotas and job control.

Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, ...

provided testing on its

Motorola 68000 The Motorola 68000 (sometimes shortened to Motorola 68k or m68k and usually pronounced "sixty-eight-thousand") is a 16/32-bit complex instruction set computer (CISC) microprocessor, introduced in 1979 by Motorola Semiconductor Products Sect ...

machines prior to release, ensuring portability of the system. The official 4.2BSD release came in August 1983. It was notable as the first version released after the 1982 departure of Bill Joy to co-found Sun Microsystems;

Mike Karels Michael J. (Mike) Karels is an American Software Engineer and one of the key people in history of BSD UNIX. A graduate of University of Notre Dame with a Bachelor of Science in Microbiology. Mike went on to University of California, Berkeley fo ...

and

took on leadership roles within the project from that point forward. On a lighter note, it also marked the debut of BSD's daemon mascot in a drawing by

John Lasseter John Alan Lasseter (; born January 12, 1957) is an American film director, producer, screenwriter, animator, voice actor, and the head of animation at Skydance Animation. He was previously the chief creative officer of Pixar Animation Studios ...

that appeared on the cover of the printed manuals distributed by USENIX.

4.3BSD

4.3BSD was released in June 1986. Its main changes were to improve the performance of many of the new contributions of 4.2BSD that had not been as heavily tuned as the 4.1BSD code. Prior to the release, BSD's implementation of TCP/IP had diverged considerably from BBN's official implementation. After several months of testing, DARPA determined that the 4.2BSD version was superior and would remain in 4.3BSD. (See also

History of the Internet The history of the Internet has its origin in information theory and the efforts of scientists and engineers to build and interconnect computer networks. The Internet Protocol Suite, the set of rules used to communicate between networks and ...

.) After 4.3BSD, it was determined that BSD would move away from the aging 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 Van Jacobson (born 1950) is an American computer scientist, renowned for his work on TCP/IP network performance and scaling.

of LBL) new TCP/IP algorithms to accommodate the growth of the Internet.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 Users Group. Until then, all versions of BSD incorporated proprietary AT&T Unix code and were, therefore, subject to an 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 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 code and was freely redistributable under the terms of the

BSD license BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD li ...

. It was released in June 1989. 4.3BSD-Reno came in early 1990. It was an interim release during the early development of 4.4BSD, and its use was considered a "gamble", hence the naming after the gambling center of

Reno, Nevada Reno ( ) is a city in the northwest section of the U.S. state of Nevada, along the Nevada-California border, about north from Lake Tahoe, known as "The Biggest Little City in the World". Known for its casino and tourism industry, Reno is the c ...

. This release was explicitly moving towards

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inte ...

compliance, and, according to some, away from the BSD philosophy (as POSIX is very much based on System V, and Reno was quite bloated compared to previous releases). Among the new features were an NFS implementation from the

University of Guelph , mottoeng = "to learn the reasons of realities" , established = May 8, 1964 ()As constituents: OAC: (1874) Macdonald Institute: (1903) OVC: (1922) , type = Public university , chancellor ...

, a status key ("Ctrl-T") and support for the

HP 9000 HP 9000 is a line of workstation and server computer systems produced by the Hewlett-Packard (HP) Company. The native operating system for almost all HP 9000 systems is HP-UX, which is based on UNIX System V. The HP 9000 brand was introduced ...

range of computers, originating in the

University of Utah The University of Utah (U of U, UofU, or simply The U) is a public research university in Salt Lake City, Utah. It is the flagship institution of the Utah System of Higher Education. The university was established in 1850 as the University of D ...

's "HPBSD" port. In August 2006, ''

InformationWeek ''InformationWeek'' is a digital magazine which conducts corresponding face-to-face events, virtual events, and research. It is headquartered in San Francisco, California California is a state in the Western United States, located alo ...

'' magazine rated 4.3BSD as the "Greatest Software Ever Written". They commented: "BSD 4.3 represents the single biggest theoretical undergirder of the Internet."

Net/2 and legal troubles

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 utilities without using the AT&T code. For example, vi, which had been based on the original Unix version of ed, was rewritten as

nvi NVI or nvi may refer to: * nvi, a text editor * Avial NV, an airline * ''no value indicator'', a non-denominated postage stamp * Navoiy Airport, in Uzbekistan * Negative volume index, a financial analysis method * ''Nationale Vliegtuig Industr ...

(new vi). Within eighteen months, all of the AT&T utilities had been replaced, and it was determined that only a few 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 The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistors 386BSD 386BSD (also known as "Jolix") is a discontinued Unix operating system based on the Berkeley Software Distribution (BSD). It was released in 1992 and ran on PC-compatible computer systems based on the 32-bit Intel 80386 microprocessor. 386BSD i ...

by William Jolitz and the proprietary BSD/386 (later renamed BSD/OS) by

Berkeley Software Design Berkeley Software Design, Inc. (BSDI or, later, BSDi), was a corporation which developed, sold licenses for, and supported BSD/OS (originally known as BSD/386), a commercial and partially proprietary variant of the BSD Unix operating system for ...

(BSDi). 386BSD itself was short-lived, but became the initial code base of the

NetBSD NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is a ...

and

FreeBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ...

projects that were started shortly thereafter. BSDi soon found itself in legal trouble with AT&T's

Unix System Laboratories Unix System Laboratories (USL), sometimes written UNIX System Laboratories to follow relevant trademark guidelines of the time, was an American software laboratory and product development company that existed from 1989 through 1993. At first wh ...

(USL) subsidiary, then the owners of the System V

copyright A copyright is a type of intellectual property that gives its owner the exclusive right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, education ...

and the Unix trademark. The '' USL v. BSDi'' lawsuit was filed in April 1992 and led to an injunction on the distribution of Net/2 until the validity of USL's copyright claims on the source could be determined. The lawsuit slowed development of the free-software descendants of BSD for nearly two years while their legal status was in question, and as a result systems based on the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

, which did not have such legal ambiguity, gained greater support. Although not released until 1992, development of

386BSD 386BSD (also known as "Jolix") is a discontinued Unix operating system based on the Berkeley Software Distribution (BSD). It was released in 1992 and ran on PC-compatible computer systems based on the 32-bit Intel 80386 microprocessor. 386BSD i ...

predated that of Linux.

Linus Torvalds Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish software engineer who is the creator and, historically, the lead developer of the Linux kernel, used by Linux distributions and other operating systems such as Android. He also ...

has said that if 386BSD or the

GNU kernel GNU Hurd is a collection of microkernel servers written as part of GNU, for the GNU Mach microkernel. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kerne ...

had been available at the time, he probably would not have created Linux.

4.4BSD and descendants

In June 1993, 4.4BSD-Encumbered was released only to USL licensees. The lawsuit was settled in January 1994, largely in Berkeley's favor. Of the 18,000 files in the Berkeley distribution, only three had to be removed and 70 modified to show USL copyright notices. A further condition of the settlement was that USL would not file further lawsuits against users and distributors of the Berkeley-owned code in the upcoming 4.4BSD release. Marshall Kirk McKusick summarizes the lawsuit and its outcome: In March 1994, 4.4BSD-Lite was released that no longer require a USL source license and also contained many other changes over the original 4.4BSD-Encumbered release. The final release from Berkeley was 1995's 4.4BSD-Lite Release 2, after which the CSRG was dissolved and development of BSD at Berkeley ceased. Since then, several variants based directly or indirectly on 4.4BSD-Lite (such as

OpenBSD OpenBSD is a security-focused operating system, security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking N ...

and

DragonFly BSD DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and FreeBSD developer between 1994 and 2003, began working on DragonFly BSD in ...

) have been maintained. In addition, the permissive nature of the BSD license has allowed many other operating systems, both free and proprietary, to incorporate BSD code. For example, Microsoft Windows has used BSD-derived code in its implementation of TCP/IP and bundles recompiled versions of BSD's

command-line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive command (computing), commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invokin ...

networking tools since

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft and oriented towards businesses. It was the direct successor to Windows NT 4.0, and was released to manufacturing on December 15, 1999, and was official ...

. Also

Darwin Darwin may refer to: Common meanings * Charles Darwin (1809–1882), English naturalist and writer, best known as the originator of the theory of biological evolution by natural selection * Darwin, Northern Territory, a territorial capital city i ...

, the system on which Apple's

macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac (computer), Mac computers. Within the market of ...

is built, is a derivative of 4.4BSD-Lite2 and FreeBSD. Various commercial Unix operating systems, such as Solaris, also contain varying amounts of BSD code.

Significant BSD descendants

BSD has been the base of a large number of operating systems. Most notable among these today are perhaps the major

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...

BSDs: FreeBSD, NetBSD and OpenBSD, which are all derived from

and

4.4BSD The History of the Berkeley Software Distribution begins in the 1970s. 1BSD (PDP-11) The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify an ...

-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 was forked in 1995 from NetBSD. A number of commercial operating systems are also partly or wholly based on BSD or its descendants, including Sun's

SunOS SunOS is a Unix-branded operating system developed by Sun Microsystems for their workstation and server computer systems. The ''SunOS'' name is usually only used to refer to versions 1.0 to 4.1.4, which were based on BSD, while versions 5.0 ...

and

Apple Inc. Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company ...

. Most of the current BSD operating systems are

and available for download, free of charge, under the

BSD License BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD li ...

, the most notable exception being

. They also generally use a

monolithic kernel A monolithic kernel is an operating system architecture where the entire operating system is working in kernel space. The monolithic model differs from other operating system architectures (such as the microkernel architecture) in that it alone d ...

architecture, apart from macOS and DragonFly BSD which feature

hybrid kernel A hybrid kernel is an operating system kernel architecture that attempts to combine aspects and benefits of microkernel and monolithic kernel architectures used in computer operating systems. Overview The traditional kernel categories are monolith ...

s. 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 The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...

Sequent In mathematical logic, a sequent is a very general kind of conditional assertion. : A_1,\,\dots,A_m \,\vdash\, B_1,\,\dots,B_n. A sequent may have any number ''m'' of condition formulas ''Ai'' (called " antecedents") and any number ''n'' of ass ...

's Dynix,

NeXT Next may refer to: Arts and entertainment Film * ''Next'' (1990 film), an animated short about William Shakespeare * ''Next'' (2007 film), a sci-fi film starring Nicolas Cage * '' Next: A Primer on Urban Painting'', a 2005 documentary film Lit ...

NeXTSTEP NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT Computer in the late 1980s and early 1990s and was initially used for its range of proprieta ...

, DEC's

Ultrix Ultrix (officially all-caps ULTRIX) is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations. History The initial development of Unix occurred on DEC equ ...

and OSF/1 AXP (now

Tru64 UNIX Tru64 UNIX is a discontinued 64-bit UNIX operating system for the Alpha instruction set architecture (ISA), currently owned by Hewlett-Packard (HP). Previously, Tru64 UNIX was a product of Compaq, and before that, Digital Equipment Corporation ( ...

). Parts of NeXT's software became the foundation for

, among the most commercially successful BSD variants in the general market. A selection of significant Unix versions and

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating systems that descend from BSD includes: *

, an open source general purpose operating system. **

NEXTSTEP NeXTSTEP is a discontinued object-oriented, multitasking operating system based on the Mach kernel and the UNIX-derived BSD. It was developed by NeXT Computer in the late 1980s and early 1990s and was initially used for its range of proprieta ...

and

OPENSTEP OpenStep is a defunct object-oriented application programming interface (API) specification for a legacy object-oriented operating system, with the basic goal of offering a NeXTSTEP-like environment on non-NeXTSTEP operating systems. OpenStep wa ...

, based on the

Mach kernel Mach () is a kernel developed at Carnegie Mellon University by Richard Rashid and Avie Tevanian to support operating system research, primarily distributed and parallel computing. Mach is often considered one of the earliest examples of a microk ...

and 4BSD; the ancestor of

***

, the core of

and

iOS iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also include ...

; built on the XNU kernel (part

Mach Mach may refer to Mach number, the speed of sound in local conditions. It may also refer to: Computing * Mach (kernel), an operating systems kernel technology * ATI Mach, a 2D GPU chip by ATI * GNU Mach, the microkernel upon which GNU Hurd is bas ...

, part FreeBSD, part Apple-derived code) and a userland much of which comes from FreeBSD **

Orbis OS The PlayStation 4 system software is the updatable firmware and operating system of the PlayStation 4. The operating system is Orbis OS, based on FreeBSD 9. Technology System The native operating system of the PlayStation 4 is Orbis OS, which ...

, Sony's fork of FreeBSD 9 is the operating system for the PS4.

CellOS The cello ( ; plural ''celli'' or ''cellos'') or violoncello ( ; ) is a bowed (sometimes plucked and occasionally hit) string instrument of the violin family. Its four strings are usually tuned in perfect fifths: from low to high, C2, G2, D ...

for the PS3 system is believed to also be a FreeBSD fork, and is known to contain FreeBSD and NetBSD code **

TrueOS TrueOS (formerly PC-BSD or PCBSD) is a discontinued Unix-like, server-oriented operating system built upon the most recent releases of FreeBSD-CURRENT. Up to 2018 it aimed to be easy to install by using a graphical installation program, and ea ...

GhostBSD GhostBSD is a Unix-like operating system based on FreeBSD, with MATE as its default desktop environment (GNOME was the previous desktop environment) and an Xfce-desktop community based edition. It aims to be easy to install, ready-to-use and easy ...

and

DesktopBSD DesktopBSD is a Unix-derivative, desktop-oriented operating system based on FreeBSD. Its goal is to combine the stability of FreeBSD with the ease-of-use of K Desktop Environment 3, which is the default graphical user interface. History an ...

, distributions of FreeBSD with emphasis on ease of use and user friendly interfaces for the desktop/laptop PC user. **

MidnightBSD MidnightBSD is a free Unix, desktop-oriented operating system originally forked from FreeBSD 6.1, and periodically updated with code and drivers from later FreeBSD releases. Its default desktop environment, Xfce, is a lightweight user friendl ...

, another fork of FreeBSD **

, a fork of FreeBSD to follow an alternative design, particularly related to

SMP SMP may refer to: Organisations * Scale Model Products, 1950s, acquired by Aluminum Model Toys * School Mathematics Project, UK developer of mathematics textbooks * '' Sekolah Menengah Pertama'', "junior high school" in Indonesia * Shanghai Mun ...

. **

NextBSD NextBSD was an operating system initially based on the trunk version of FreeBSD as of August 2015. It is a fork of FreeBSD which implements new features developed on branches but not yet implemented in FreeBSD. As of 2019 the website seems defun ...

, new BSD distribution derived from FreeBSD 10.1 and various macOS components. **

FreeNAS TrueNAS is the branding for a range of free and open-source network-attached storage (NAS) operating systems produced by iXsystems, and based on FreeBSD and Linux, using the OpenZFS file system. It is licensed under the terms of the BS ...

a free network-attached storage server based on a minimal version of FreeBSD. **

NAS4Free XigmaNAS is network-attached storage (NAS) server software with a dedicated management web interface (written in PHP). It is free software under the terms of the Simplified BSD license. XigmaNAS is a continuation of the original FreeNAS code, ...

fork of 0.7

version, Network attached storage server. ** Nokia IPSO (IPSO SB variant), the FreeBSD-based OS used in

Nokia Nokia Corporation (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational telecommunications, information technology, and consumer electronics corporation, established in 1865. Nokia's main headquarters are in Espoo, Finlan ...

Firewall Appliances. ** The OS for the Netflix Open Connect Appliance. **

Junos Junos OS (also known as Juniper Junos, Junos and JUNOS) is a FreeBSD-based network operating system used in Juniper Networks routing, switching and security devices. Versioning Junos OS was first made available on 7 July 1998, with new featur ...

, the operating system for Juniper routers, a customized version of FreeBSD, and a variety of other embedded operating systems **

Isilon Systems Dell EMC Isilon is a scale out network-attached storage platform offered by Dell EMC for high-volume storage, backup and archiving of unstructured data. It provides a cluster-based storage array based on industry standard hardware, and is scalab ...

' OneFS, the operating system used on Isilon IQ-series clustered storage systems, is a heavily customized version of FreeBSD. **

NetApp NetApp, Inc. is an American hybrid cloud data services and data management company headquartered in San Jose, California. It has ranked in the Fortune 500 from 2012–2021. Founded in 1992 with an IPO in 1995, NetApp offers cloud data services ...

's Data ONTAP, the operating system for NetApp filers, is a customized version of FreeBSD with the ONTAP architecture built on top. **

m0n0wall m0n0wall was an embedded firewall distribution of FreeBSD, one of the BSD operating system descendants. It provides a small image which can be put on Compact Flash cards as well as on CD-ROMs and hard disks. It runs on a number of embedded ...

, a FreeBSD distribution tweaked for usage as a firewall. **

pfSense pfSense is a firewall/ router computer software distribution based on FreeBSD. The open source pfSense Community Edition (CE) and pfSense Plus is installed on a physical computer or a virtual machine to make a dedicated firewall/router for a ...

free open source FreeBSD based firewall/router. **

OPNsense __NOTOC__ OPNsense is an open source, FreeBSD-based firewall and routing software developed by Deciso, a company in the Netherlands that makes hardware and sells support packages for OPNsense. It is a fork of pfSense, which in turn was forked fr ...

, firewall, a fork of pfSense **

Coyote Point Systems Coyote Point Systems was a manufacturer of computer networking equipment for application traffic management, also known as server load balancing. In March 2013, the company was acquired by Fortinet. The company introduced hardware-based server ...

EQ/OS, a hardened high-performance runtime for server load balancing. *

, an open source BSD focused on clean design and portability. **

, a 1995

fork In cutlery or kitchenware, a fork (from la, furca ' pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tines with which one can spear foods ...

of NetBSD, focused on security. **

Force10 Dell Force10 (formerly nCore Networks, Force10 Networks), was a United States company that developed and marketed 10 Gigabit and 40 Gigabit Ethernet switches for computer networking to corporate, educational, and governmental customers. It had ...

FTOS FTOS or Force10 Operating System is the firmware family used on Force10 Ethernet switches. It has a similar functionality as Cisco's NX-OS or Juniper's Junos. FTOS 10 is running on Debian. As part of a re-branding strategy of Dell FTOS will be re ...

, the operating system for Force 10 and

Dell Dell is an American based technology company. It develops, sells, repairs, and supports computers and related products and services. Dell is owned by its parent company, Dell Technologies. Dell sells personal computers (PCs), servers, data ...

datacenter network switches. ***

DNOS DNOS or Dell Networking Operating System is a network operating system running on switches from Dell Networking. It is derived from either the PowerConnect OS (DNOS 6.x) or Force10 OS/FTOS (DNOS 9.x) and will be made available for the 10G and fast ...

version 9 and above, the successor to

. *

TrustedBSD FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD), which was based on Research Unix. The first version of FreeBSD was released in 1993. In 2005, FreeBSD was the most popular ope ...

F5 Networks F5, Inc. is an American technology company specializing in application security, multi-cloud management, online fraud prevention, application delivery networking (ADN), application availability & performance, network security, and access & autho ...

, F5 BIGIP Appliances used a BSD OS as the management OS until version 9.0 was released, which is built on top of Linux. * DEC's

, the official version of Unix for its

PDP-11 The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were so ...

, VAX, and

DECstation The DECstation was a brand of computers used by DEC, and refers to three distinct lines of computer systems—the first released in 1978 as a word processing system, and the latter (more widely known) two both released in 1989. These compri ...

systems * Sony NEWS-OS, a BSD-based operating system for their network engineering workstations *

OSF/1 OSF/1 is a variant of the Unix operating system developed by the Open Software Foundation during the late 1980s and early 1990s. OSF/1 is one of the first operating systems to have used the Mach kernel developed at Carnegie Mellon University, an ...

, a hybrid kernel based Unix developed by the

Open Software Foundation The Open Software Foundation (OSF) was a not-for-profit industry consortium for creating an open standard for an implementation of the operating system Unix. It was formed in 1988 and merged with X/Open in 1996, to become The Open Group. Despite ...

, incorporating a modified

and parts of 4BSD **

(formerly DEC OSF/1 AXP or Digital UNIX), the port of

for

DEC Alpha Alpha (original name Alpha AXP) is a 64-bit reduced instruction set computer (RISC) instruction set architecture (ISA) developed by Digital Equipment Corporation (DEC). Alpha was designed to replace 32-bit VAX complex instruction set computer ...

-based systems from DEC,

Compaq Compaq Computer Corporation (sometimes abbreviated to CQ prior to a 2007 rebranding) was an American information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced ...

and HP. * Pre-5.0 versions of

, an enhanced version of 4BSD for the Sun

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...

68k The Motorola 68000 series (also known as 680x0, m68000, m68k, or 68k) is a family of 32-bit complex instruction set computer (CISC) microprocessors. During the 1980s and early 1990s, they were popular in personal computers and workstations and ...

-based

Sun-2 The Sun-2 series of UNIX workstations and servers was launched by Sun Microsystems in November 1983. As the name suggests, the Sun-2 represented the second generation of Sun systems, superseding the original Sun-1 series. The Sun-2 series used a ...

and

Sun-3 Sun-3 is a series of UNIX computer workstations and servers produced by Sun Microsystems, launched on September 9, 1985. The Sun-3 series are VMEbus-based systems similar to some of the earlier Sun-2 series, but using the Motorola 68020 micropr ...

systems,

SPARC SPARC (Scalable Processor Architecture) is a reduced instruction set computer (RISC) instruction set architecture originally developed by Sun Microsystems. Its design was strongly influenced by the experimental Berkeley RISC system developed ...

-based systems, and x86-based

Sun386i The Sun386i (codenamed ''Roadrunner'') is a discontinued hybrid UNIX workstation/ PC compatible computer system produced by Sun Microsystems, launched in 1988. It is based on the Intel 80386 microprocessor but shares many features with the contemp ...

systems (SunOS 5.0 and later versions are

System V Release 4 Unix System V (pronounced: "System Five") is one of the first commercial versions of the Unix operating system. It was originally developed by AT&T and first released in 1983. Four major versions of System V were released, numbered 1, 2, 3, an ...

-based) *

, the first open source BSD-based operating system and the ancestor of most current BSD systems *

DEMOS Demos may refer to: Computing * DEMOS, a Soviet Unix-like operating system * DEMOS (ISP), the first internet service provider in the USSR * Demos Commander, an Orthodox File Manager for Unix-like systems * plural for Demo (computer programming ...

, a Soviet BSD clone *

BSD/OS BSD/OS (originally called BSD/386 and sometimes known as BSDi) is a discontinued proprietary version of the BSD operating system developed by Berkeley Software Design, Inc. (BSDi). BSD/OS had a reputation for reliability in server roles; the re ...

, a (now defunct) proprietary BSD for PCs
RetroBSD
a fork of BSD 2.11 designed to run on microcontrollers such as the

PIC32 PIC (usually pronounced as ''"pick"'') is a family of microcontrollers made by Microchip Technology, derived from the PIC1650"PICmicro Family Tree", PIC16F Seminar Presentation originally developed by General Instrument's Microelectronics ...

LiteBSD
a variant of 4.4BSD Unix for PIC32MZ microcontrollers

References

External links

A timeline of BSD and Research UNIX
{{Berkeley Software Distribution, state=expanded Berkeley Software Distribution History of free and open-source software History of software