The history of the Berkeley Software Distribution began in the 1970s when

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

received a copy of

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

. Professors and students at the university began adding software to the operating system and released it as

BSD The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...

to select universities. Since it contained proprietary Unix code, it originally had to be distributed subject to AT&T licenses. The bundled software from AT&T was then rewritten and released as free software 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 lic ...

. However, this resulted in a lawsuit with Unix System Laboratories, the AT&T subsidiary responsible for Unix. Eventually, in the 1990s, the final versions of BSD were publicly released without any proprietary licenses, which led to many descendants of the operating system that are still maintained today.

1BSD (PDP-11)

The earliest distributions of Unix from

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

in the 1970s included the

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

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 In Ancient Greece, the symposium (, ''sympósion'', from συμπίνειν, ''sympínein'', 'to drink together') was the part of a banquet that took place after the meal, when drinking for pleasure was accompanied by music, dancing, recitals, o ...

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 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; "an extended period of time intentionally spent on something that’s not your routine job." The concept of the sabbatical is based on the Bi ...

from Bell Labs and came to Berkeley as a visiting professor. He helped to install Version 6 Unix 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 ...

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 is the physiological basis of visual perception (the ability to detect and process light). The system detects, transduces and interprets information concerning light within the visible range to construct an image and buil ...

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 ...

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

Eric Schmidt Eric Emerson Schmidt (born April 27, 1955) is an American businessman and former computer engineer who was the chief executive officer of Google from 2001 to 2011 and the company's chairman, executive chairman from 2011 to 2015. He also was the ...

as part of his master's thesis 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 line of computers, new releases of 2BSD for the PDP-11 were still issued and distributed through

USENIX USENIX is an American 501(c)(3) nonprofit membership organization based in Berkeley, California and founded in 1975 that supports advanced computing systems, operating system (OS), and computer networking research. It organizes several confe ...

; for example, 1982's 2.8.1BSD included a collection of fixes for performance problems in

Version 7 Unix Version 7 Unix, also called Seventh Edition 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 commerc ...

, 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. Unlike the previous releases, it required split instruction/data space, to accommodate the ever-increasing size of its utility programs. In the 21st century, maintenance updates from volunteers continued: patch ''#490'' was released on April 16, 2025.

3BSD

A DEC 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 Hamburg, Manch ...

to the VAX architecture, UNIX/32V, 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 ver ...

capabilities. The kernel of 32V was largely rewritten by Berkeley graduate student Özalp Babaoğlu 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 Adva ...

'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 the Defense Advanced Research Projects Agency. History Profes ...

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

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 ancestor 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 t ...

), "reliable"

signals A signal is both the process and the result of Signal transmission, transmission of data over some transmission media, media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processin ...

, and the Curses 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 Computer network, networking prior to the commercialization of the Internet. He has also written about risk ...

''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., an abbreviation for its predecessor's former name, the American Telephone and Telegraph Company, is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the w ...

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 ...

. Several tapes have turned up, all with a label that says 4.1BSD, yet differences between the tapes are present. The software development that would lead from 4.1BSD to 4.2BSD was funded from sources including ARPA, Order Number 4031, Contract N00039-82-C-0235 which was in effect at least from November 15, 1981 through September 30, 1983.

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 communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...

implementation; 4.1b from June 1982 included the new Berkeley Fast File System, implemented by

Marshall Kirk McKusick Marshall Kirk McKusick (born January 19, 1954) is an American computer scientist, known for his extensive work on BSD UNIX, from the 1980s to FreeBSD in the present day. He served on the board of the USENIX Association from 1986 to 1992 and aga ...

; 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 Research Unix refers to the 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). The term ''Research Unix'' first app ...

, and a commercially supported version was available from mt Xinu. To guide the design of 4.2BSD, Duane Adams of

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 Adva ...

formed a "steering committee" consisting of Bob Fabry,

and Sam Leffler from Berkeley, Alan Nemeth and Rob Gurwitz from BBN,

Dennis Ritchie Dennis MacAlistair Ritchie (September 9, 1941 – October 12, 2011) was an American computer scientist. He created the C programming language and the Unix operating system and B language with long-time colleague Ken Thompson. Ritchie and Thomp ...

from

, Keith Lantz from

Stanford Leland Stanford Junior University, commonly referred to as Stanford University, is a private research university in Stanford, California, United States. It was founded in 1885 by railroad magnate Leland Stanford (the eighth governor of and th ...

, Rick Rashid from

Carnegie Mellon Carnegie may refer to: People *Carnegie (surname), including a list of people with the name **Andrew Carnegie, Scottish-American industrialist and philanthropist * Clan Carnegie, a lowland Scottish clan Institutions Named for Andrew Carnegie * ...

, Bert Halstead from

MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...

, Dan Lynch from ISI, and Gerald J. Popek of

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school then known as the southern branch of the C ...

. 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.

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

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 Sector ...

machines prior to release, improving portability of the system. Sun hardware support is plainly visible in the 4.1c BSD artifacts in the CSRG ISO. 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. Karels (August 2, 1956 – June 2, 2024) was an American software engineer and one of the key figures in history of BSD UNIX. Biography Karels graduated from the University of Notre Dame with a degree in microbiology and from the Un ...

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, and animator. He was previously the chief creative officer of Pixar Animation Studios, Walt Disney Animation Studios, and Disneytoon Studios, a ...

that appeared on the cover of the printed manuals distributed by

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 originated in the efforts of scientists and engineers to build and interconnect computer networks. The Internet protocol suite, Internet Protocol Suite, the set of rules used to communicate between networks and devi ...

.) 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. Computer Consoles, Inc. or CCI was a telephony and computer company located in Rochester, New York, United States, which did business first as a private, and then ultimately a public company from 1968 to 1990. CCI provided worldwide telephone comp ...

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 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

. 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. It is the county seat and most populous city of Washoe County, Nevada, Washoe County. Sitting in the High Eastern Sierra foothills, ...

. This release explicitly moved 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 application programming interfaces (APIs), along with comm ...

compliance. Among the new features were an NFS implementation from the

University of Guelph The University of Guelph (abbreviated U of G) is a comprehensive Public university, public research university in Guelph, Ontario, Canada. It was established in 1964 after the amalgamation of Ontario Agricultural College (1874), the MacDonald I ...

, a status key ("Ctrl-T") and support for the HP 9000 range of computers, originating in the

University of Utah The University of Utah (the U, U of U, or simply Utah) is a public university, public research university in Salt Lake City, Utah, United States. It was established in 1850 as the University of Deseret (Book of Mormon), Deseret by the General A ...

'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 U.S. state, state in the Western United State ...

'' 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 (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, aka Network(ing) 2 or 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 the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit computing, 32-bit processor in the line, making it a significant evolution in ...

architecture: the free

386BSD 386BSD (also known as "Jolix") is a Unix-like operating system that was developed by couple Lynne and William "Bill" Jolitz. Released as free and open source in 1992, it was the first fully operational Unix built to run on IBM PC-compatible s ...

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 software company founded in 1991 by members of the Computer Systems Research Group (CSRG), known for developing and selling BSD/OS (originally known as BSD/386), a commercial and part ...

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

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

and

FreeBSD FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable ...

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 legal 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, ...

and the Unix trademark. The '' USL v. BSDi'' lawsuit was filed in April 1992 and led to an

injunction An injunction is an equitable remedy in the form of a special court order compelling a party to do or refrain from doing certain acts. It was developed by the English courts of equity but its origins go back to Roman law and the equitable rem ...

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 software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the k ...

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

predated that of Linux.

Linus Torvalds Linus Benedict Torvalds ( , ; born 28 December 1969) is a Finnish software engineer who is the creator and lead developer of the Linux kernel. He also created the distributed version control system Git. He was honored, along with Shinya Yam ...

has said that if 386BSD or the GNU kernel had been available at the time, he probably would not have created Linux.

4.4BSD and descendants

In August 1992, 4.4BSD-Alpha was released. 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 software, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by fork (software development), forking NetBSD ...

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 Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

has used BSD-derived code in its implementation of TCP/IP and bundles recompiled versions of BSD's

command-line A command-line interface (CLI) is a means of interacting with software via commands each formatted as a line of text. Command-line interfaces emerged in the mid-1960s, on computer terminals, as an interactive and more user-friendly alternativ ...

networking tools since

Windows 2000 Windows 2000 is a major release of the Windows NT operating system developed by Microsoft, targeting the server and business markets. It is the direct successor to Windows NT 4.0, and was Software release life cycle#Release to manufacturing (RT ...

. Also Darwin, the system on which Apple's

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

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 and view the source code, design documents, or content of the product. The open source model is a decentrali ...

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

and

4.4BSD The history of the Berkeley Software Distribution began in the 1970s when University of California, Berkeley received a copy of Research Unix, Unix. Professors and students at the university began adding software to the operating system and releas ...

-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 from 1982 until the mid-1990s. The ''SunOS'' name is usually only used to refer to versions 1.0 to 4.1.4, which were based ...

and

Apple Inc. Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Comput ...

. 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 lic ...

, the most notable exception being

. They also generally use a

monolithic kernel A monolithic kernel is an operating system software architecture, architecture with the entire operating system running in kernel space. The monolithic model differs from other architectures such as the microkernel in that it alone defines a high ...

architecture, apart from macOS and DragonFly BSD which feature

hybrid kernel A hybrid kernel is an operating system Kernel (operating system), kernel whose architecture attempts to combine aspects and benefits of microkernel and monolithic kernel architectures used in operating systems. Overview The traditional kernel cat ...

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 centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

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, Inc. (later NeXT Computer, Inc. and NeXT Software, Inc.) was an American technology company headquartered in Redwood City, California that specialized in computer workstations for higher education and business markets, and later develope ...

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, founded by Steve Jobs, in the late 1980s and early 1990s and was initially used for its ...

, 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 eq ...

and OSF/1 AXP (now

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

). 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, *nix 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 Uni ...

operating systems that descend from BSD includes: *

, an open source general purpose operating system. ** Orbis OS, Sony's fork of FreeBSD 9 is the operating system for the PS4.

CellOS The violoncello ( , ), commonly abbreviated as cello ( ), is a middle pitched 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, ...

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

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

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

, a fork of FreeBSD to follow an alternative design, particularly related to SMP. ** NextBSD, new BSD distribution derived from FreeBSD 10.1 and various macOS components. ** FreeNAS a free network-attached storage server based on a minimal version of FreeBSD. ** NAS4Free fork of 0.7 FreeNAS version, Network attached storage server. ** Nokia IPSO (IPSO SB variant), the FreeBSD-based OS used in

Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...

Firewall Appliances. ** The OS for the Netflix Open Connect Appliance. ** Junos, the operating system for Juniper routers, a customized version of FreeBSD, and a variety of other embedded operating systems ** Isilon Systems' 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 data infrastructure company that provides unified data storage, integrated data services, and cloud operations (CloudOps) solutions to enterprise customers. The company is based in San Jose, California. It has ranked ...

'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 (networking), firewall distribution of FreeBSD, one of the Berkeley Software Distribution, BSD operating system descendants. It provided a small image which could be put on flash memory, Compact Flash cards as w ...

, 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 In computing, a virtual machine (VM) is ...

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. Launched in 2015, it is a Fork_(software_development) ...

, firewall, a fork of pfSense ** Coyote Point Systems EQ/OS, a hardened high-performance runtime for server load balancing. *

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

, a 1995 fork of NetBSD, focused on security. ** Force10 FTOS, the operating system for Force 10 and

Dell Dell Inc. is an American technology company that develops, sells, repairs, and supports personal computers (PCs), Server (computing), servers, data storage devices, network switches, software, computer peripherals including printers and webcam ...

datacenter network switches. ***

DNOS version 9 and above, the successor to FTOS. *

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, founded by Steve Jobs, in the late 1980s and early 1990s and was initially used for its ...

and

OPENSTEP OpenStep is an object-oriented application programming interface (API) specification developed by NeXT. It provides a framework for building graphical user interfaces (GUIs) and developing software applications. OpenStep was designed to be plat ...

, based on the

Mach kernel Mach () is an operating system 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 ...

and 4BSD; the ancestor of

's Darwin, the core of

and

iOS Ios, Io or Nio (, ; ; locally Nios, Νιός) is a Greek island in the Cyclades group in the Aegean Sea. Ios is a hilly island with cliffs down to the sea on most sides. It is situated halfway between Naxos and Santorini. It is about long an ...

; built on the XNU kernel (part

Mach The Mach number (M or Ma), often only Mach, (; ) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a Boundary (thermodynamic), boundary to the local speed of sound. It is named after the Austrian physi ...

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

TrustedBSD FreeBSD is a free-software Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version was released in 1993 developed from 386BSD, one of the first fully functional and free Unix clones on affordable h ...

* F5 Networks, 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 originally sold by Digital Equipment Corporation (DEC) from 1970 into the late 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of a ...

, VAX, and

DECstation The DECstation was a brand of computers used by Digital Equipment Corporation, 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 ...

systems * Sony NEWS-OS, a BSD-based operating system for their network engineering workstations * OSF/1, a hybrid kernel based Unix developed by the

Open Software Foundation The Open Software Foundation, Inc. (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. ...

, incorporating a modified

and parts of 4BSD **

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

-based systems from DEC,

Compaq Compaq Computer Corporation was an American information technology, information technology company founded in 1982 that developed, sold, and supported computers and related products and services. Compaq produced some of the first IBM PC compati ...

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. It was founded by brothers Paul and Joseph Galvin in 1928 and had been named Motorola since 1947. Many of Motorola's products had been ...

68k-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 ...

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 mic ...

systems, SPARC-based systems, and

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...

-based Sun386i systems (SunOS 5.0 and later versions are System V Release 4-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, a (now defunct) proprietary BSD for PCs

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 Software topical history overviews