Berkeley Software Distribution
Encyclopedia
Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is a Unix
operating system
derivative developed and distributed by the Computer Systems Research Group
(CSRG) of the University of California, Berkeley
, from 1977 to 1995. Today the term "BSD" is often non-specifically used to refer to any of the BSD descendants which together form a branch of the family of Unix-like
operating systems. Operating systems derived from the original BSD code
remain actively developed and widely used.
Historically, BSD has been considered a branch of UNIX—"BSD UNIX", because it shared the initial codebase and design with the original AT&T
UNIX operating system. In the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary UNIX variants such as DEC
ULTRIX
and Sun Microsystems
SunOS
. This can be attributed to the ease with which it could be licensed, and the familiarity it found among the founders of many technology companies of this era.
Though these proprietary BSD derivatives were largely superseded by the UNIX System V Release 4 and OSF/1 systems in the 1990s (both of which incorporated BSD code and are the basis of other modern Unix systems), later BSD releases provided a basis for several open source
development projects, e.g. FreeBSD
, NetBSD
, OpenBSD
or DragonFly
, that are ongoing. These, in turn, have been incorporated in whole or in part in modern proprietary operating systems, e.g the TCP/IP networking code in Microsoft Windows
or the foundation of Apple's Mac OS X
.
File:Unix history-simple.png|250px|thumb|Evolution of Unix
systems
default
in the 1970s included the source code
to the operating system, allowing researchers at universities
to modify and extend Unix. The first Unix system at Berkeley was a PDP-11
installed in 1974, and the computer science
department used it for extensive research thereafter.
Other universities became interested in the software at Berkeley, and so in 1977 Bill Joy
, then a graduate student at Berkeley, started compiling the first Berkeley Software Distribution (1BSD), which was released on March 9, 1978. 1BSD was an add-on to Sixth Edition Unix rather than a complete operating system in its own right; its main components were a Pascal compiler
and Joy's ex line editor
.
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
version of ex
) and the C shell
.
Later releases of 2BSD contained ports of changes to 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 Version 7 Unix
) rather than a set of applications and patches. The most recent release, 2.11BSD, was first released in 1992. As of 2008, maintenance updates from volunteers are still continuing, with patch 447 being released on December 31, 2008.
of Unix to the VAX architecture, UNIX/32V
, did not take advantage of the VAX's virtual memory
capabilities. The kernel of 32V was largely rewritten by Berkeley students to include a virtual memory implementation, and a complete operating system including the new kernel, ports of the 2BSD utilities to the VAX, and the utilities from 32V was released as 3BSD at the end of 1979. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX (for Virtual Memory Unix), and BSD kernel images were normally called /vmunix until 4.4BSD.
The success of 3BSD was a major factor in the Defense Advanced Research Projects Agency
's (DARPA) decision to fund Berkeley's Computer Systems Research Group
(CSRG), which would develop a standard Unix platform for future DARPA research in the VLSI Project
. CSRG released 4BSD, containing numerous improvements to the 3BSD system, in October 1980.
4BSD (November 1980) offered a number of enhancements over 3BSD, notably job control in the previously released csh
, delivermail
(the antecedent of sendmail
), "reliable" signals
, and the Curses
programming library.
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 Bill Joy
until it could perform as well as VMS on several benchmarks. (The release would have been called 5BSD, but after objections from AT&T
the name was changed; AT&T feared confusion with AT&T
's UNIX System V
. One early, never-released test version was in fact called 4.5BSD.)
4.2BSD would take over two years to implement and contained several major overhauls. Before its official release came three intermediate versions: 4.1a incorporated a modified version of BBN's preliminary TCP/IP implementation; 4.1b included the new Berkeley Fast File System, implemented by Marshall Kirk McKusick
; and 4.1c was an interim release during the last few months of 4.2BSD's development.
To guide the design of 4.2BSD Duane Adams of DARPA formed a "steering committee" consisting of Bob Fabry
, Bill Joy
and Sam Leffler from UCB
, Alan Nemeth and Rob Gurwitz from BBN
, Dennis Ritchie
from Bell Labs
, Keith Lantz from Stanford, Rick Rashid from Carnegie-Mellon, Bert Halstead from MIT
, Dan Lynch from ISI
, and Gerald J. Popek
of UCLA
. The committee met from April 1981 to June 1983.
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 and Marshall Kirk McKusick
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
that appeared on the cover of the printed manuals distributed by USENIX
.
.)
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
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 BSD license. 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
. This release was explicitly moving towards POSIX
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 was an NFS
implementation from the University of Guelph
.
In August 2006, Information Week magazine rated 4.3BSD as the "Greatest Software Ever Written". They commented: "BSD 4.3 represents the single biggest theoretical undergirder of the Internet."
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 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
architecture: the free 386BSD
by William Jolitz
and the proprietary
BSD/386
(later renamed BSD/OS) by Berkeley Software Design
(BSDi). 386BSD itself was short-lived, but became the initial code base of the NetBSD
and FreeBSD
projects that were started shortly thereafter.
BSDi soon found itself in legal trouble with AT&T's Unix System Laboratories
(USL) subsidiary, then the owners of the System V copyright
and the Unix trademark
. The USL v. BSDi
lawsuit was filed in 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
, which did not have such legal ambiguity, gained greater support. Although not released until 1992, development of 386BSD
predated that of Linux. Linus Torvalds
has said that if 386BSD had been available at the time, he probably would not have created Linux.
In June 1994, 4.4BSD was released in two forms: the freely distributable 4.4BSD-Lite contained no AT&T source, whereas 4.4BSD-Encumbered was available, as earlier releases had been, only to AT&T licensees.
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 FreeBSD
, NetBSD
, OpenBSD
and DragonFly BSD
) 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
networking tools with Windows 2000. Also Darwin
, the system on which Apple's Mac OS X
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.
stacks: Berkeley sockets
. By integrating sockets with the Unix operating system's file descriptor
s, it became almost as easy to read and write data across a network
as it was to access a disk. The AT&T laboratory eventually released their own STREAMS
library, which incorporated much of the same functionality in a software stack with a better architecture, but the wide distribution of the existing sockets library, together with the unfortunate omission of a function call for polling a set of open sockets equivalent to the select call in the Berkeley library, reduced the impact of the new API
. Early versions of BSD were used to form Sun Microsystems
' SunOS
, founding the first wave of popular Unix workstations.
Today, BSD continues to serve as a technological testbed for academic organizations. It can be found in use in numerous commercial and free products, and, increasingly, in embedded devices
. The general quality of its source code, as well as its documentation (especially reference manual pages, commonly referred to as man pages), make it well-suited for many purposes.
The permissive nature of the BSD license allows companies to distribute derived products as proprietary software
without exposing source code and sometimes intellectual property
to competitors. Searching for strings containing "University of California, Berkeley" in the documentation of products, in the static data sections of binaries
and ROMs
, or as part of other information about a software program, will often show BSD code has been used. This permissiveness also makes BSD code suitable for use in open source
products, and the license is compatible with many other open source licenses. The permissive nature of the BSD license also allows derivative works of code released originally under the BSD license to become less permissive with time.
BSD operating systems can run much native software of several other operating systems on the same architecture
, using a binary compatibility layer
. Much simpler and faster than emulation
, this allows, for instance, applications intended for Linux
to be run at effectively full speed. This makes BSDs not only suitable for server environments, but also for workstation ones, given the increasing availability of commercial or closed-source software for Linux only. This also allows administrators to migrate legacy commercial applications, which may have only supported commercial Unix variants, to a more modern operating system, retaining the functionality of such applications until they can be replaced by a better alternative.
Current BSD operating system variants support many of the common IEEE
, ANSI
, ISO
, and POSIX
standards, while retaining most of the traditional BSD behavior. Like AT&T Unix, the BSD kernel is monolithic
, meaning that device drivers in the kernel run in privileged mode, as part of the core of the operating system.
BSD has been the base of a large number of operating systems. Most notable among these today are perhaps the major open source
BSDs: FreeBSD, NetBSD and OpenBSD, which are all derived from 386BSD
and 4.4BSD-Lite by various routes. Both NetBSD and FreeBSD started life in 1993, initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite code base. OpenBSD was forked
in 1995 from NetBSD. The three most notable descendants in current use—sometimes known as the BSDs—have themselves spawned a number of children, including DragonFly BSD
, FreeSBIE
, MirOS BSD
, DesktopBSD
, and PC-BSD
. They are targeted at an array of systems for different purposes and are common in government facilities, universities and in commercial use. A number of commercial operating systems are also partly or wholly based on BSD or its descendants, including Sun's
SunOS
and Apple Inc.'s Mac OS X
.
Most of the current BSD operating systems are open source
and available for download, free of charge, under the BSD License, the most notable exception being Mac OS X
. They also generally use a monolithic kernel
architecture, apart from Mac OS X and DragonFly BSD which feature hybrid kernel
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
's SunOS
, Sequent
's Dynix
, NeXT
's NeXTSTEP
, DEC
's Ultrix
and OSF/1 AXP (now Tru64 UNIX
). Of these, only the last is still currently supported in its original form. Parts of NeXT's software became the foundation for Mac OS X
, among the most commercially successful BSD variants in the general market.
A selection of significant Unix versions and Unix-like
operating systems that descend from BSD includes:
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
derivative developed and distributed by the Computer Systems Research Group
Computer Systems Research Group
The Computer Systems Research Group 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 :...
(CSRG) of the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, from 1977 to 1995. Today the term "BSD" is often non-specifically used to refer to any of the BSD descendants which together form a branch of the family of Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems. Operating systems derived from the original BSD code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
remain actively developed and widely used.
Historically, BSD has been considered a branch of UNIX—"BSD UNIX", because it shared the initial codebase and design with the original AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
UNIX operating system. In the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary UNIX variants such as DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
ULTRIX
Ultrix
Ultrix was the brand name of Digital Equipment Corporation's native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound.-History:...
and Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
SunOS
SunOS
SunOS is a version of the Unix 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 of SunOS...
. This can be attributed to the ease with which it could be licensed, and the familiarity it found among the founders of many technology companies of this era.
Though these proprietary BSD derivatives were largely superseded by the UNIX System V Release 4 and OSF/1 systems in the 1990s (both of which incorporated BSD code and are the basis of other modern Unix systems), later BSD releases provided a basis for several open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
development projects, e.g. FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
, NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
, OpenBSD
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
or DragonFly
Dragonfly
A dragonfly is a winged insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera . It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body...
, that are ongoing. These, in turn, have been incorporated in whole or in part in modern proprietary operating systems, e.g the TCP/IP networking code in Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
or the foundation of Apple's Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
.
History
File:Unix history-simple.png|250px|thumb|Evolution of Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
systems
default
PDP-11 beginnings
The earliest distributions of Unix from Bell LabsBell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
in the 1970s included the source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
to the operating system, allowing researchers at universities
University
A university is an institution of higher education and research, which grants academic degrees in a variety of subjects. A university is an organisation that provides both undergraduate education and postgraduate education...
to modify and extend Unix. The first Unix system at Berkeley was a PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
installed in 1974, and the computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
department used it for extensive research thereafter.
Other universities became interested in the software at Berkeley, and so in 1977 Bill Joy
Bill Joy
William Nelson Joy , commonly known as Bill Joy, is an American computer scientist. Joy co-founded Sun Microsystems in 1982 along with Vinod Khosla, Scott McNealy and Andy Bechtolsheim, and served as chief scientist at the company until 2003...
, then a graduate student at Berkeley, started compiling the first Berkeley Software Distribution (1BSD), which was released on March 9, 1978. 1BSD was an add-on to Sixth Edition Unix rather than a complete operating system in its own right; its main components were a Pascal compiler
Compiler
A compiler is a computer program that transforms source code written in a programming language into another computer language...
and Joy's ex line editor
Line editor
A line editor is a text editor computer program that manipulates text primarily by the display, modification, and movement of lines. Line editors precede screen-based text editors and originated in an era when a computer operator typically interacted with a teleprinter , with no video display, and...
.
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
Vi
vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...
text editor (a visual
Visual editor
Visual editors or full screen editors are editing programs which display the text being edited on the screen as it is being edited, as opposed to line-oriented editors ....
version of ex
Ex (text editor)
ex, short for EXtended, is a line editor for Unix systems.The original ex was an advanced version of the standard Unix editor ed, included in the Berkeley Software Distribution...
) and the C shell
C shell
The C shell is a Unix shell that was created by Bill Joy while a graduate student at University of California, Berkeley in the late 1970s. It has been distributed widely, beginning with the 2BSD release of the BSD Unix system that Joy began distributing in 1978...
.
Later releases of 2BSD contained ports of changes to the VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
-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 Version 7 Unix
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 commercialization of Unix by AT&T in the early 1980s...
) rather than a set of applications and patches. The most recent release, 2.11BSD, was first released in 1992. As of 2008, maintenance updates from volunteers are still continuing, with patch 447 being released on December 31, 2008.
VAX versions
A VAX computer was installed at Berkeley in 1978, but the portPorting
In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed...
of Unix to the VAX architecture, UNIX/32V
UNIX/32V
UNIX/32V was an early version of the Unix operating system from Bell Laboratories, released in June 1979. 32V was a direct port of the PDP-11 Seventh Edition Unix to the DEC VAX architecture....
, did not take advantage of the VAX's virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
capabilities. The kernel of 32V was largely rewritten by Berkeley students to include a virtual memory implementation, and a complete operating system including the new kernel, ports of the 2BSD utilities to the VAX, and the utilities from 32V was released as 3BSD at the end of 1979. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX (for Virtual Memory Unix), and BSD kernel images were normally called /vmunix until 4.4BSD.
The success of 3BSD was a major factor in the Defense Advanced Research Projects Agency
Defense Advanced Research Projects Agency
The Defense Advanced Research Projects Agency is an agency of the United States Department of Defense responsible for the development of new technology for use by the military...
's (DARPA) decision to fund Berkeley's Computer Systems Research Group
Computer Systems Research Group
The Computer Systems Research Group 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 :...
(CSRG), which would develop a standard Unix platform for future DARPA research in the VLSI Project
VLSI Project
DARPA's VLSI Project 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 VLSI. Although little known, notably in comparison to their work on what became the internet, the VLSI Project is likely...
. CSRG released 4BSD, containing numerous improvements to the 3BSD system, in October 1980.
4BSD (November 1980) offered a number of enhancements over 3BSD, notably job control in the previously released csh
C shell
The C shell is a Unix shell that was created by Bill Joy while a graduate student at University of California, Berkeley in the late 1970s. It has been distributed widely, beginning with the 2BSD release of the BSD Unix system that Joy began distributing in 1978...
, delivermail
Delivermail
The ancestor of sendmail, delivermail is a mail transport agent that used the FTP protocol on the early ARPANET to transmit e-mail to the recipient....
(the antecedent of sendmail
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 used for email transport over the Internet....
), "reliable" signals
Signal (computing)
A signal is a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. Essentially it is an asynchronous notification sent to a process in order to notify it of an event that occurred. When a signal is sent to a process, the operating system...
, and the Curses
Curses (programming library)
curses is a terminal control library for Unix-like systems, enabling the construction of text user interface applications.The name is a pun on the term “cursor optimization”. It is a library of functions that manage an application's display on character-cell terminals .- Overview :The curses API...
programming library.
4.1BSD (June 1981) was a response to criticisms of BSD's performance relative to the dominant VAX operating system, VMS
OpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
. The 4.1BSD kernel was systematically tuned up by Bill Joy
Bill Joy
William Nelson Joy , commonly known as Bill Joy, is an American computer scientist. Joy co-founded Sun Microsystems in 1982 along with Vinod Khosla, Scott McNealy and Andy Bechtolsheim, and served as chief scientist at the company until 2003...
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
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
the name was changed; AT&T feared confusion with AT&T
AT&T
AT&T Inc. is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services...
's UNIX System V
UNIX System V
Unix System V, commonly abbreviated SysV , is one of the first commercial versions of the Unix operating system. It was originally developed by American Telephone & Telegraph and first released in 1983. Four major versions of System V were released, termed Releases 1, 2, 3 and 4...
. One early, never-released test version was in fact called 4.5BSD.)
4.2BSD would take over two years to implement and contained several major overhauls. Before its official release came three intermediate versions: 4.1a incorporated a modified version of BBN's preliminary TCP/IP implementation; 4.1b included the new Berkeley Fast File System, implemented by Marshall Kirk McKusick
Marshall Kirk McKusick
Marshall Kirk McKusick is a computer scientist, known for his extensive work on BSD, 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 2004, and still serves on the board. He is also on the editorial board of...
; and 4.1c was an interim release during the last few months of 4.2BSD's development.
To guide the design of 4.2BSD Duane Adams of DARPA formed a "steering committee" consisting of Bob Fabry
Bob Fabry
Bob Fabry, while a computer science professor at the University of California, Berkeley, conceived of the idea of obtaining DARPA funding for a radically improved version of AT&T Unix and started the Computer Systems Research Group.- References :...
, Bill Joy
Bill Joy
William Nelson Joy , commonly known as Bill Joy, is an American computer scientist. Joy co-founded Sun Microsystems in 1982 along with Vinod Khosla, Scott McNealy and Andy Bechtolsheim, and served as chief scientist at the company until 2003...
and Sam Leffler from UCB
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
, Alan Nemeth and Rob Gurwitz from BBN
BBN
BBN might refer to:* BBN Technologies, formerly Bolt, Beranek and Newman, a technology company in Cambridge, Massachusetts, best known for its work on packet switching technology and its construction of the Interface Message Processor - the first router...
, Dennis Ritchie
Dennis Ritchie
Dennis MacAlistair Ritchie , was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the UNIX operating system...
from Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
, Keith Lantz from Stanford, Rick Rashid from Carnegie-Mellon, Bert Halstead from MIT
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
, Dan Lynch from ISI
Information Sciences Institute
The Information Sciences Institute is a research and development unit of the University of Southern California's Viterbi School of Engineering which focuses on computer and communications technology and information processing...
, and Gerald J. Popek
Gerald J. Popek
Gerald John "Jerry" Popek was an American computer scientist, known for his research on operating systems and virtualization.With Robert P...
of UCLA
University of California, Los Angeles
The University of California, Los Angeles is a public research university located in the Westwood neighborhood of Los Angeles, California, USA. It was founded in 1919 as the "Southern Branch" of the University of California and is the second oldest of the ten campuses...
. The committee met from April 1981 to June 1983.
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
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
; Mike Karels and Marshall Kirk McKusick
Marshall Kirk McKusick
Marshall Kirk McKusick is a computer scientist, known for his extensive work on BSD, 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 2004, and still serves on the board. He is also on the editorial board of...
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
BSD Daemon
The BSD daemon, nicknamed Beastie, is the generic mascot of BSD operating systems.-Overview:The BSD daemon is named after a software daemon, a computer program found on Unix-like operating systems, which through a play on words takes the cartoon shape of a mythical demon. The BSD daemon's nickname...
in a drawing by John Lasseter
John Lasseter
John Alan Lasseter is an American animator, director and the chief creative officer at Pixar and Walt Disney Animation Studios. He is also currently the Principal Creative Advisor for Walt Disney Imagineering....
that appeared on the cover of the printed manuals distributed by USENIX
USENIX
-External links:* *...
.
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 InternetHistory of the Internet
The history of the Internet starts in the 1950s and 1960s with the development of computers. This began with point-to-point communication between mainframe computers and terminals, expanded to point-to-point connections between computers and then early research into packet switching...
.)
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.
Computer Consoles Inc. or CCI was a telephony and computer company located in Rochester, New York, USA, which did business first as a private, and then ultimately a public company from 1968 to 1990...
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
Van Jacobson is one of the primary contributors to the TCP/IP protocol stack which is the technological foundation of today’s Internet. He is renowned for his pioneering achievements in network performance and scaling....
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
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
under the terms of the BSD license. 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
Gambling
Gambling is the wagering of money or something of material value on an event with an uncertain outcome with the primary intent of winning additional money and/or material goods...
center of Reno, Nevada
Reno, Nevada
Reno is the county seat of Washoe County, Nevada, United States. The city has a population of about 220,500 and is the most populous Nevada city outside of the Las Vegas metropolitan area...
. This release was explicitly moving towards POSIX
POSIX
POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
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 was an NFS
Network File System
Network File System is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing...
implementation from the University of Guelph
University of Guelph
The University of Guelph, also known as U of G, is a comprehensive public research university in Guelph, Ontario, Canada. It was established in 1964 after the amalgamation of Ontario Agricultural College, the Macdonald Institute, and the Ontario Veterinary College...
.
In August 2006, Information Week 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 BosticKeith Bostic
Keith Bostic is a computer programmer from the United States.In 1986, Bostic joined the Computer Systems Research Group at the University of California, Berkeley. He was one of the principal architects of the Berkeley 4.4BSD and 4.4BSD-Lite releases...
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
Vi
vi is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, and the ex editor language supported within these programs, is described by the Single Unix Specification and POSIX.The original code for vi...
, which had been based on the original Unix version of ed, was rewritten as nvi
Nvi
nvi is a re-implementation of the classic Berkeley text editor, ex/vi, traditionally distributed with BSD, and later, Unix systems. It was originally distributed as part of the Fourth Berkeley Software Distribution ....
(new vi). Within eighteen months, all 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
Intel 80386
The Intel 80386, also known as the i386, or just 386, was a 32-bit microprocessor introduced by Intel in 1985. The first versions had 275,000 transistors and were used as the central processing unit of many workstations and high-end personal computers of the time...
architecture: the free 386BSD
386BSD
386BSD, sometimes called "Jolix", was a free Unix-like operating system based on BSD, first released in 1992. It ran on PC compatible computer systems based on the Intel 80386 microprocessor...
by William Jolitz
William Jolitz
William Frederick Jolitz , commonly known as Bill Jolitz, is best known for developing the 386BSD operating system from 1989 to 1994 along with his wife Lynne Jolitz.Jolitz received his BA in Computer Science from UC Berkeley....
and the proprietary
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
BSD/386
BSD/OS
BSD/OS was a proprietary version of the BSD operating system developed by Berkeley Software Design, Inc. ....
(later renamed BSD/OS) by Berkeley Software Design
Berkeley Software Design
Berkeley Software Design Inc. was a corporation which developed, sold licenses for, and supported BSD/OS , a commercial and partially proprietary variant of the BSD Unix operating system for PC compatible computer systems...
(BSDi). 386BSD itself was short-lived, but became the initial code base of the NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
and FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
projects that were started shortly thereafter.
BSDi soon found itself in legal trouble with AT&T's Unix System Laboratories
Unix System Laboratories
Unix System Laboratories was originally organized as part of Bell Labs in 1989. USL joined with the UNIX Software Operation, also a Bell Laboratories division, in 1990. It assumed responsibility for Unix development and licensing activities...
(USL) subsidiary, then the owners of the System V copyright
Copyright
Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...
and the Unix trademark
Trademark
A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...
. The USL v. BSDi
USL v. BSDi
USL v. BSDi was a lawsuit brought in the United States in 1992 by Unix System Laboratories against Berkeley Software Design, Inc and the Regents of the University of California over intellectual property related to UNIX...
lawsuit was filed in 1992 and led to an injunction
Injunction
An injunction is an equitable remedy in the form of a court order that requires a party to do or refrain from doing certain acts. A party that fails to comply with an injunction faces criminal or civil penalties and may have to pay damages or accept sanctions...
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
Linux kernel
The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software....
, which did not have such legal ambiguity, gained greater support. Although not released until 1992, development of 386BSD
386BSD
386BSD, sometimes called "Jolix", was a free Unix-like operating system based on BSD, first released in 1992. It ran on PC compatible computer systems based on the Intel 80386 microprocessor...
predated that of Linux. Linus Torvalds
Linus Torvalds
Linus Benedict Torvalds is a Finnish software engineer and hacker, best known for having initiated the development of the open source Linux kernel. He later became the chief architect of the Linux kernel, and now acts as the project's coordinator...
has said that if 386BSD had been available at the time, he probably would not have created Linux.
4.4BSD and descendants
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.In June 1994, 4.4BSD was released in two forms: the freely distributable 4.4BSD-Lite contained no AT&T source, whereas 4.4BSD-Encumbered was available, as earlier releases had been, only to AT&T licensees.
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 FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
, NetBSD
NetBSD
NetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
, OpenBSD
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
and DragonFly BSD
DragonFly BSD
DragonFly BSD is a free Unix-like operating system created as a fork of FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and a FreeBSD developer between 1994 and 2003, began work on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on July...
) 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
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
has used BSD-derived code in its implementation of TCP/IP and bundles recompiled versions of BSD's command-line
Command-line interface
A command-line interface is a mechanism for interacting with a computer operating system or software by typing commands to perform specific tasks...
networking tools with Windows 2000. Also Darwin
Darwin (operating system)
Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000. It is composed of code developed by Apple, as well as code derived from NeXTSTEP, BSD, and other free software projects....
, the system on which Apple's Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
is built, is a derivative of 4.4BSD-Lite2 and FreeBSD. Various commercial UNIX operating systems, such as Solaris
Solaris Operating System
Solaris is a Unix operating system originally developed by Sun Microsystems. It superseded their earlier SunOS in 1993. Oracle Solaris, as it is now known, has been owned by Oracle Corporation since Oracle's acquisition of Sun in January 2010....
, also contain varying amounts of BSD code.
Technology
Berkeley's Unix was the first Unix to include libraries supporting the Internet ProtocolInternet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
stacks: Berkeley sockets
Berkeley sockets
The Berkeley sockets application programming interface comprises a library for developing applications in the C programming language that perform inter-process communication, most commonly for communications across a computer network....
. By integrating sockets with the Unix operating system's file descriptor
File descriptor
In computer programming, a file descriptor is an abstract indicator for accessing a file. The term is generally used in POSIX operating systems...
s, it became almost as easy to read and write data across a network
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
as it was to access a disk. The AT&T laboratory eventually released their own STREAMS
STREAMS
In computer networking, STREAMS is the native framework in Unix System V for implementing character devices.STREAMS was designed as a modular architecture for implementing full-duplex I/O between kernel or user space processes and device drivers. Its most frequent uses have been in developing...
library, which incorporated much of the same functionality in a software stack with a better architecture, but the wide distribution of the existing sockets library, together with the unfortunate omission of a function call for polling a set of open sockets equivalent to the select call in the Berkeley library, reduced the impact of the new API
Application programming interface
An application programming interface is a source code based specification intended to be used as an interface by software components to communicate with each other...
. Early versions of BSD were used to form Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
' SunOS
SunOS
SunOS is a version of the Unix 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 of SunOS...
, founding the first wave of popular Unix workstations.
Today, BSD continues to serve as a technological testbed for academic organizations. It can be found in use in numerous commercial and free products, and, increasingly, in embedded devices
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
. The general quality of its source code, as well as its documentation (especially reference manual pages, commonly referred to as man pages), make it well-suited for many purposes.
The permissive nature of the BSD license allows companies to distribute derived products as proprietary software
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
without exposing source code and sometimes intellectual property
Intellectual property
Intellectual property is a term referring to a number of distinct types of creations of the mind for which a set of exclusive rights are recognized—and the corresponding fields of law...
to competitors. Searching for strings containing "University of California, Berkeley" in the documentation of products, in the static data sections of binaries
Executable
In computing, an executable file causes a computer "to perform indicated tasks according to encoded instructions," as opposed to a data file that must be parsed by a program to be meaningful. These instructions are traditionally machine code instructions for a physical CPU...
and ROMs
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
, or as part of other information about a software program, will often show BSD code has been used. This permissiveness also makes BSD code suitable for use in open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
products, and the license is compatible with many other open source licenses. The permissive nature of the BSD license also allows derivative works of code released originally under the BSD license to become less permissive with time.
BSD operating systems can run much native software of several other operating systems on the same architecture
Computer architecture
In computer science and engineering, computer architecture is the practical art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals and the formal modelling of those systems....
, using a binary compatibility layer
Compatibility layer
A compatibility layer is a term that refers to components that allow for non-native support of components.In software engineering, a compatibility layer allows binaries for a legacy or foreign system to run on a host system. This translates system calls for the foreign system into native system...
. Much simpler and faster than emulation
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
, this allows, for instance, applications intended for Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
to be run at effectively full speed. This makes BSDs not only suitable for server environments, but also for workstation ones, given the increasing availability of commercial or closed-source software for Linux only. This also allows administrators to migrate legacy commercial applications, which may have only supported commercial Unix variants, to a more modern operating system, retaining the functionality of such applications until they can be replaced by a better alternative.
Current BSD operating system variants support many of the common IEEE
Institute of Electrical and Electronics Engineers
The Institute of Electrical and Electronics Engineers is a non-profit professional association headquartered in New York City that is dedicated to advancing technological innovation and excellence...
, ANSI
American National Standards Institute
The American National Standards Institute is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organization also coordinates U.S. standards with international...
, ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
, and POSIX
POSIX
POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...
standards, while retaining most of the traditional BSD behavior. Like AT&T Unix, the BSD kernel is monolithic
Monolithic kernel
A monolithic kernel is an operating system architecture where the entire operating system is working in the kernel space and alone as supervisor mode...
, meaning that device drivers in the kernel run in privileged mode, as part of the core of the operating system.
Significant BSD descendants
- See also: :Category:BSD and Comparison of BSD operating systemsComparison of BSD operating systemsThere are a number of Unix-like operating systems based on or descended from the Berkeley Software Distribution series of Unix variants. The three most notable descendants in current use are FreeBSD, OpenBSD, and NetBSD, which are all derived from 386BSD and 4.4BSD-Lite, by various routes...
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
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
BSDs: FreeBSD, NetBSD and OpenBSD, which are all derived from 386BSD
386BSD
386BSD, sometimes called "Jolix", was a free Unix-like operating system based on BSD, first released in 1992. It ran on PC compatible computer systems based on the Intel 80386 microprocessor...
and 4.4BSD-Lite by various routes. Both NetBSD and FreeBSD started life in 1993, initially derived from 386BSD, but in 1994 migrating to a 4.4BSD-Lite code base. OpenBSD was forked
Fork (software development)
In software engineering, a project fork happens when developers take a legal copy of source code from one software package and start independent development on it, creating a distinct piece of software...
in 1995 from NetBSD. The three most notable descendants in current use—sometimes known as the BSDs—have themselves spawned a number of children, including DragonFly BSD
DragonFly BSD
DragonFly BSD is a free Unix-like operating system created as a fork of FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and a FreeBSD developer between 1994 and 2003, began work on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on July...
, FreeSBIE
FreeSBIE
FreeSBIE is a live CD, an operating system that is able to load directly from a bootable CD with no installation process or hard disk. It is based on the FreeBSD operating system. Its name is a pun on frisbee. Currently, FreeSBIE uses Xfce and Fluxbox....
, MirOS BSD
MirOS BSD
MirOS BSD is a free and open source operating system, which started as a fork of OpenBSD 3.1 in August 2002. It is intended to maintain the security of OpenBSD - from which it frequently synchronises code updates - with better support for European localisation...
, DesktopBSD
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 KDE, which is the default graphical user interface.- History and development :...
, and PC-BSD
PC-BSD
PC-BSD is a Unix-like, desktop-oriented operating system based on FreeBSD. It aims to be easy to install by using a graphical installation program, and easy and ready-to-use immediately by providing KDE SC as the pre-installed graphical user interface. PC-BSD provides official binary nVidia and...
. They are targeted at an array of systems for different purposes and are common in government facilities, universities and in commercial use. A number of commercial operating systems are also partly or wholly based on BSD or its descendants, including Sun's
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
SunOS
SunOS
SunOS is a version of the Unix 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 of SunOS...
and Apple Inc.'s Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
.
Most of the current BSD operating systems are open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
and available for download, free of charge, under the BSD License, the most notable exception being Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
. They also generally use a monolithic kernel
Monolithic kernel
A monolithic kernel is an operating system architecture where the entire operating system is working in the kernel space and alone as supervisor mode...
architecture, apart from Mac OS X and DragonFly BSD which feature hybrid kernel
Hybrid kernel
A hybrid kernel is a kernel architecture based on combining aspects of microkernel and monolithic kernel architectures used in computer operating systems. The category is controversial due to the similarity to monolithic kernel; the term has been dismissed by Linus Torvalds as simple marketing...
s. The various open source BSD projects generally develop the kernel and userland
Userland
Userland may refer to:* Userland , operating system software that does not belong in the kernel* UserLand Software, a U.S. software company specializing in web applications* Radio UserLand, a computer program to aid maintaining blogs or podcasts...
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
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
's SunOS
SunOS
SunOS is a version of the Unix 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 of SunOS...
, Sequent
Sequent Computer Systems
Sequent Computer Systems, or Sequent, was a computer company that designed and manufactured multiprocessing computer systems. They were among the pioneers in high-performance symmetric multiprocessing open systems, innovating in both hardware and software Sequent Computer Systems, or Sequent, was...
's Dynix
Dynix
Dynix is an operating system developed by Sequent. It is a flavor of Unix based on BSD. DYNIX was replaced by DYNIX/ptx, which was based on the System V version of UNIX produced by AT&T....
, NeXT
NeXT
Next, Inc. was an American computer company headquartered in Redwood City, California, that developed and manufactured a series of computer workstations intended for the higher education and business markets...
's NeXTSTEP
NEXTSTEP
NeXTSTEP was the object-oriented, multitasking operating system developed by NeXT Computer to run on its range of proprietary workstation computers, such as the NeXTcube...
, DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
's Ultrix
Ultrix
Ultrix was the brand name of Digital Equipment Corporation's native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound.-History:...
and OSF/1 AXP (now Tru64 UNIX
Tru64 UNIX
Tru64 UNIX is a 64-bit UNIX operating system for the Alpha instruction set architecture , currently owned by Hewlett-Packard . Previously, Tru64 UNIX was a product of Compaq, and before that, Digital Equipment Corporation , where it was known as Digital UNIX .As its original name suggests, Tru64...
). Of these, only the last is still currently supported in its original form. Parts of NeXT's software became the foundation for Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
, among the most commercially successful BSD variants in the general market.
A selection of significant Unix versions and Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
operating systems that descend from BSD includes:
- FreeBSDFreeBSDFreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
, a major open source effort focusing on performance and the x86 platform.- DragonFly BSDDragonFly BSDDragonFly BSD is a free Unix-like operating system created as a fork of FreeBSD 4.8. Matthew Dillon, an Amiga developer in the late 1980s and early 1990s and a FreeBSD developer between 1994 and 2003, began work on DragonFly BSD in June 2003 and announced it on the FreeBSD mailing lists on July...
, a fork of FreeBSD to follow an alternative design, particularly related to SMPSymmetric multiprocessingIn computing, symmetric multiprocessing involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance. Most common multiprocessor systems today use an SMP architecture...
. - PC-BSDPC-BSDPC-BSD is a Unix-like, desktop-oriented operating system based on FreeBSD. It aims to be easy to install by using a graphical installation program, and easy and ready-to-use immediately by providing KDE SC as the pre-installed graphical user interface. PC-BSD provides official binary nVidia and...
and DesktopBSDDesktopBSDDesktopBSD 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 KDE, which is 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. - FreeNASFreeNASFreeNAS is a free network-attached storage server, supporting: CIFS , FTP, NFS, rsync, AFP protocols, iSCSI, S.M.A.R.T., local user authentication, and software RAID , with a web-based configuration interface. FreeNAS takes less than 64 MB once installed on CompactFlash, hard drive or USB flash...
a free network-attached storage server based on a minimal version of FreeBSD. - Nokia IPSONokia IPSOCheck Point IPSO is the operating system for the 'Check Point firewall' appliance and other security devices, based on FreeBSD, with numerous hardening features applied.....
(IPSO SB variant), the FreeBSD-based OS used in NokiaNokiaNokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
Firewall Appliances. - Juniper NetworksJuniper NetworksJuniper Networks is an information technology and computer networking products multinational company, founded in 1996. It is head quartered in Sunnyvale, California, USA. The company designs and sells high-performance Internet Protocol network products and services...
JunOS, the operating system for Juniper routers, a customized version of FreeBSD, and a variety of other embedded operating systems - Apple Inc.'s DarwinDarwin (operating system)Darwin is an open source POSIX-compliant computer operating system released by Apple Inc. in 2000. It is composed of code developed by Apple, as well as code derived from NeXTSTEP, BSD, and other free software projects....
, the core of Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
; built on the XNU kernelXNUXNU is the computer operating system kernel that Apple Inc. acquired and developed for use in the Mac OS X operating system and released as free and open source software as part of the Darwin operating system...
(part MachMach (kernel)Mach is an operating system kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. Although Mach is often mentioned as one of the earliest examples of a microkernel, not all versions of Mach are microkernels...
, part FreeBSD, part Apple-derived code) and a userland much of which comes from FreeBSD - Isilon SystemsIsilon SystemsIsilon Systems, a division of EMC, is headquartered in Seattle, Washington, USA and sells clustered storage systems and software for digital content and other unstructured data, which includes but is not limited to video, audio, digital images, computer models, PDF files, scanned information, and...
' OneFS, the operating system used on Isilon IQ-series clustered storage systems, is a heavily customized version of FreeBSD. - NetApp's ONTAP GX, the operating system for NetApp filers, is a customized version of FreeBSD with the ONTAP GX architecture built on top.
- DragonFly BSD
- NetBSDNetBSDNetBSD is a freely available open source version of the Berkeley Software Distribution Unix operating system. It was the second open source BSD descendant to be formally released, after 386BSD, and continues to be actively developed. The NetBSD project is primarily focused on high quality design,...
, an open source BSD with an emphasis on portability and clean design.- OpenBSDOpenBSDOpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
, a 1995 forkFork (software development)In software engineering, a project fork happens when developers take a legal copy of source code from one software package and start independent development on it, creating a distinct piece of software...
of NetBSD, focuses on portability, standardization, correctness, proactive security and integrated cryptography.
- OpenBSD
- F5 NetworksF5 NetworksF5 Networks, Inc. is a networking appliances company. It is headquartered in Seattle, Washington and has development and marketing offices worldwide. It originally manufactured and sold some of the very first load balancing products...
, 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 UltrixUltrixUltrix was the brand name of Digital Equipment Corporation's native Unix systems. While ultrix is the Latin word for avenger, the name was chosen solely for its sound.-History:...
, the official version of Unix for its PDP-11PDP-11The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
, VAX, and DECstationDECstationThe 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 two both released in 1989. These comprised a range of computer workstations based on the MIPS architecture and a...
systems - OSF/1, a microkernelMicrokernelIn computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system . These mechanisms include low-level address space management, thread management, and inter-process communication...
-based UNIX developed by the Open Software FoundationOpen Software FoundationThe Open Software Foundation was a not-for-profit organization founded in 1988 under the U.S. National Cooperative Research Act of 1984 to create an open standard for an implementation of the UNIX operating system.-History:...
, incorporating the Mach kernel and parts of 4BSD- Tru64 UNIXTru64 UNIXTru64 UNIX is a 64-bit UNIX operating system for the Alpha instruction set architecture , currently owned by Hewlett-Packard . Previously, Tru64 UNIX was a product of Compaq, and before that, Digital Equipment Corporation , where it was known as Digital UNIX .As its original name suggests, Tru64...
(formerly DEC OSF/1 AXP or Digital UNIX), the port of OSF/1 for DEC AlphaDEC AlphaAlpha, originally known as Alpha AXP, is a 64-bit reduced instruction set computer instruction set architecture developed by Digital Equipment Corporation , designed to replace the 32-bit VAX complex instruction set computer ISA and its implementations. Alpha was implemented in microprocessors...
-based systems from DECDigital Equipment CorporationDigital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
, CompaqCompaqCompaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....
and HPHewlett-PackardHewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
.
- Tru64 UNIX
- Early versions of Sun MicrosystemsSun MicrosystemsSun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
SunOSSunOSSunOS is a version of the Unix 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 of SunOS...
(up to SunOS 4.1.4), an enhanced version of 4BSD for the Sun MotorolaMotorolaMotorola, Inc. was an American multinational telecommunications company based in Schaumburg, Illinois, which was eventually divided into two independent public companies, Motorola Mobility and Motorola Solutions on January 4, 2011, after losing $4.3 billion from 2007 to 2009...
68k68kThe Motorola 680x0/m68000/68000 is a family of 32-bit CISC microprocessors. During the 1980s and early 1990s, they were popular in personal computers and workstations and were the primary competitors of Intel's x86 microprocessors...
-based Sun-2Sun-2The 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...
and Sun-3Sun-3Sun-3 was the name given to a series of UNIX computer workstations and servers produced by Sun Microsystems, launched on September 9th, 1985. The Sun-3 series were VMEbus-based systems similar to some of the earlier Sun-2 series, but using the Motorola 68020 microprocessor, in combination with the...
systems, SPARCSPARCSPARC is a RISC instruction set architecture developed by Sun Microsystems and introduced in mid-1987....
-based systems, and x86-based Sun386iSun386iThe Sun386i was a hybrid UNIX workstation/PC compatible computer system produced by Sun Microsystems, launched in 1988. It was based on the Intel 80386 microprocessor but shared many features with the contemporary Sun-3 series systems....
systems. - NeXTNeXTNext, Inc. was an American computer company headquartered in Redwood City, California, that developed and manufactured a series of computer workstations intended for the higher education and business markets...
NEXTSTEPNEXTSTEPNeXTSTEP was the object-oriented, multitasking operating system developed by NeXT Computer to run on its range of proprietary workstation computers, such as the NeXTcube...
and OPENSTEPOpenStepOpenStep was an object-oriented application programming interface specification for an object-oriented operating system that used a non-NeXTSTEP operating system as its core, principally developed by NeXT with Sun Microsystems. OPENSTEP was a specific implementation of the OpenStep API developed...
, based on the Mach kernel and 4BSD; the ancestor of Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems... - 386BSD386BSD386BSD, sometimes called "Jolix", was a free Unix-like operating system based on BSD, first released in 1992. It ran on PC compatible computer systems based on the Intel 80386 microprocessor...
, the first open source BSD-based operating system and the ancestor of most current BSD systems - DEMOSDEMOSDEMOS was a Unix-like operating system developed in the Soviet Union...
, a SovietSoviet UnionThe Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
BSD clone - BSD/OSBSD/OSBSD/OS was a proprietary version of the BSD operating system developed by Berkeley Software Design, Inc. ....
, a (now defunct) proprietary BSD for PCs
See also
- BSD DaemonBSD DaemonThe BSD daemon, nicknamed Beastie, is the generic mascot of BSD operating systems.-Overview:The BSD daemon is named after a software daemon, a computer program found on Unix-like operating systems, which through a play on words takes the cartoon shape of a mythical demon. The BSD daemon's nickname...
- BSD licensesBSD licensesBSD licenses are a family of permissive free software licenses. The original license was used for the Berkeley Software Distribution , a Unix-like operating system after which it is named....
- Comparison of BSD operating systemsComparison of BSD operating systemsThere are a number of Unix-like operating systems based on or descended from the Berkeley Software Distribution series of Unix variants. The three most notable descendants in current use are FreeBSD, OpenBSD, and NetBSD, which are all derived from 386BSD and 4.4BSD-Lite, by various routes...
- List of BSD operating systems
External links
- A timeline of BSD and Research UNIX
- UNIX History – History of UNIX and BSD using diagrams
- The Design and Implementation of the 4.4BSD Operating System