"BSD" redirects here. For the Microsoft Windows error message abbreviated "BSOD", see Blue Screen of Death. For the family of free software licenses, see BSD licenses. For other uses, see BSD (disambiguation).
BSD was initially called Berkeley Unix because it was based on the source code of the original Unix developed at Bell Labs. In the 1980s, BSD was widely adopted by workstation vendors in the form of proprietary Unix variants such as DECUltrix and Sun MicrosystemsSunOS due to its permissive licensing and familiarity to many technology company founders and engineers. These proprietary BSD derivatives were largely superseded in the 1990s by UNIX SVR4 and OSF/1.
The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify and extend Unix. The operating system arrived at Berkeley in 1974, at the request of computer science professor Bob Fabry who had been on the program committee for the Symposium on Operating Systems Principles where Unix 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.[10]
BSD began life as a variant of Unix that programmers at the University of California at Berkeley, initially led by Bill Joy, began developing in the late 1970s. It included extra features, which were intertwined with code owned by AT&T.
In 1975, Ken Thompson took a sabbatical 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 improved Thompson's Pascal and implemented an improved text editor, ex.[10] 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.[11] 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.[10]
The second Berkeley Software Distribution (2BSD), released in May 1979,[12] 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. Some 75 copies of 2BSD were sent out by Bill Joy.[10]
The VAX-11/780, a typical minicomputer used for early BSD timesharing systems
A VAX computer was installed at Berkeley in 1978, but the port 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 to include Berkeley graduate student Özalp Babaoğlu's 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.
After 4.3BSD was released in June 1986, 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.
In addition to 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.[13]
Until then, all versions of BSD used 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.
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. Within eighteen months, all of the AT&T utilities had been replaced, and it was determined that only a few AT&T files remained in the kernel. These files were removed, and the result was the June 1991 release of Networking Release 2 (Net/2), a nearly complete operating system that was freely distributable.
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. 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.[14]
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.
The permissive nature of the BSD license has allowed many other operating systems, both open-source and proprietary, to incorporate BSD source code. For example, Microsoft Windows used BSD code in its implementation of TCP/IP[15] and bundles recompiled versions of BSD's command-line networking tools since Windows 2000.[16]Darwin, the basis for Apple's macOS and iOS, is based on 4.4BSD-Lite2 and FreeBSD. Various commercial Unix operating systems, such as Solaris, also incorporate BSD code.
Relationship to Research Unix
Starting with the 8th Edition, versions of Research Unix at Bell Labs had a close relationship to BSD. This began when 4.1cBSD for the VAX was used as the basis for Research Unix 8th Edition. This continued in subsequent versions, such as the 9th Edition, which incorporated source code and improvements from 4.3BSD. The result was that these later versions of Research Unix were closer to BSD than they were to System V. In a Usenet posting from 2000, Dennis Ritchie described this relationship between BSD and Research Unix:[17][bettersourceneeded]
Research Unix 8th Edition started from (I think) BSD 4.1c, but with enormous amounts scooped out and replaced by our own stuff. This continued with 9th and 10th. The ordinary user command-set was, I guess, a bit more BSD-flavored than SysVish, but it was pretty eclectic.
Relationship to System V
Eric S. Raymond summarizes the longstanding relationship between System V and BSD, stating, "The divide was roughly between longhairs and shorthairs; programmers and technical people tended to line up with Berkeley and BSD, more business-oriented types with AT&T and System V."[18]
In 1989, David A. Curry wrote about the differences between BSD and System V. He characterized System V as being often regarded as the "standard Unix." However, he described BSD as more popular among university and government computer centers, due to its advanced features and performance:[19]
Most university and government computer centers that use UNIX use Berkeley UNIX, rather than System V. There are several reasons for this, but perhaps the two most significant are that Berkeley UNIX provides networking capabilities that until recently (Release 3.0) were completely unavailable in System V, and that Berkeley UNIX is much more suited to a research environment, which requires a faster file system, better virtual memory handling, and a larger variety of programming languages.
Berkeley's Unix was the first Unix to include libraries supporting the Internet Protocol stacks: Berkeley sockets. A Unix implementation of IP's predecessor, the ARPAnet's NCP, with FTP and Telnet clients, had been produced at the University of Illinois in 1975, and was available at Berkeley.[20][21] However, the memory scarcity on the PDP-11 forced a complicated design and performance problems.[22]
By integrating sockets with the Unix operating system's file descriptors, it became almost as easy to read and write data across a network as it was to access a disk. The AT&T laboratory eventually released their own STREAMS library, which incorporated much of the same functionality in a software stack with a different architecture, but the wide distribution of the existing sockets library reduced the impact of the new API. Early versions of BSD were used to form Sun Microsystems' SunOS, founding the first wave of popular Unix workstations.
Binary compatibility
Some BSD operating systems can run native software of several other operating systems on the same architecture, using a binary compatibility layer. This is much simpler and faster than emulation; for example, it allows 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.
Standards
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.
Several operating systems are based on BSD, including FreeBSD, OpenBSD, NetBSD, MidnightBSD, MirOS BSD, GhostBSD, Darwin and DragonFly BSD. Both NetBSD and FreeBSD were created in 1993. They were initially derived from 386BSD (also known as "Jolix"), and merged the 4.4BSD-Lite source code in 1994. OpenBSD was forked from NetBSD in 1995, and DragonFly BSD was forked from FreeBSD in 2003.
386BSD is a discontinued operating system based on the Berkeley Software Distribution (BSD) that was developed by couple Lynne and William Jolitz. Released on March 17, 1992, it was the first fully operational Unix operating system to be completely free and open source.
Ultrix is the brand name of Digital Equipment Corporation's (DEC) discontinued native Unix operating systems for the PDP-11, VAX, MicroVAX and DECstations.
The Unix file system (UFS) is a family of file systems supported by many Unix and Unix-like operating systems. It is a distant descendant of the original filesystem used by Version 7 Unix.
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 the Unix operating system; a culmination of the Unix wars. The case was settled out of court in 1994 after the judge expressed doubt in the validity of USL's intellectual property, with Novell and the University agreeing not to litigate further over the Berkeley Software Distribution (BSD).
Unix System V 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, and 4. System V Release 4 (SVR4) was commercially the most successful version, being the result of an effort, marketed as Unix System Unification, which solicited the collaboration of the major Unix vendors. It was the source of several common commercial Unix features. System V is sometimes abbreviated to SysV.
The BSD Daemon, nicknamed Beastie, is the generic mascot of BSD operating systems. The BSD Daemon is named after software daemons, a class of long-running computer programs in Unix-like operating systems—which, through a play on words, takes the cartoon shape of a demon. The BSD Daemon's nickname Beastie is a slurred phonetic pronunciation of BSD. Beastie customarily carries a trident to symbolize a software daemon's forking of processes. The FreeBSD web site has noted Evi Nemeth's 1988 remarks about cultural-historical daemons in the Unix System Administration Handbook: "The ancient Greeks' concept of a 'personal daemon' was similar to the modern concept of a 'guardian angel' ... As a rule, UNIX systems seem to be infested with both daemons and demons."
The Computer Systems Research Group (CSRG) was a research group at the University of California, Berkeley that was dedicated to enhancing AT&T Unix operating system and funded by Defense Advanced Research Projects Agency.
Keith Bostic is an American software engineer and one of the key people in the history of Berkeley Software Distribution (BSD) Unix and open-source software.
BSD/OS is a discontinued proprietary version of the BSD operating system developed by Berkeley Software Design, Inc. (BSDi).
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. The name was chosen for its similarity to "Berkeley Software Distribution" the source of its primary product.
UNIX/32V is an early version of the Unix operating system from Bell Laboratories, released in June 1979. 32V was a direct port of the Seventh Edition Unix to the DEC VAX architecture.
The history of Unix dates back to the mid-1960s, when the Massachusetts Institute of Technology, AT&T Bell Labs, and General Electric were jointly developing an experimental time-sharing operating system called Multics for the GE-645 mainframe. Multics introduced many innovations, but also had many problems. Bell Labs, frustrated by the size and complexity of Multics but not its aims, slowly pulled out of the project. Their last researchers to leave Multics – among them Ken Thompson, Dennis Ritchie, Doug McIlroy, and Joe Ossanna – decided to redo the work, but on a much smaller scale.
In BSD-derived computer operating systems and in related operating systems such as SunOS, a disklabel is a record stored on a data storage device such as a hard disk that contains information about the location of the partitions on the disk. Disklabels were introduced in the 4.3BSD-Tahoe release. Disklabels are usually edited using the disklabel utility. In later versions of FreeBSD, this was renamed as bsdlabel.
FreeBSD is a free and open-source Unix-like operating system descended from the Berkeley Software Distribution (BSD). The first version of FreeBSD was released in 1993 developed from 386BSD and the current version runs on x86, ARM, PowerPC and RISC-V processors. The project is supported and promoted by the FreeBSD Foundation.
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 license was used for its namesake, the Berkeley Software Distribution (BSD), a Unix-like operating system. The original version has since been revised, and its descendants are referred to as modified BSD licenses.
NetBSD is a free and open-source Unix operating system based on the Berkeley Software Distribution (BSD). It was the first open-source BSD descendant officially released after 386BSD was forked. It continues to be actively developed and is available for many platforms, including servers, desktops, handheld devices, and embedded systems.
Michael J. (Mike) Karels is an American software engineer and one of the key figures in history of BSD UNIX.
NextBSD was an operating system initially based on the trunk version of FreeBSD as of August 2015. It was a fork of FreeBSD which implemented new features developed on branches, but not yet implemented in FreeBSD. As of 2019, the website is defunct, with the last commits on GitHub dating to October 2019. The Wayback Machine captures of the website after December 15, 2017 are domain squatter pages, and as of March 17, 2021, the site is redirects to a fake "Apple Support" page.
The History of the Berkeley Software Distribution begins in the 1970s.
↑ Quarterman, John S.; Silberschatz, Abraham; Peterson, James L. (December 1985). "4.2BSD and 4.3BSD as examples of the Unix system". Computing Surveys. 17 (4): 379–418. CiteSeerX10.1.1.117.9743. doi:10.1145/6041.6043. S2CID5700897.
Bibliography
Marshall K. McKusick, Keith Bostic, Michael J. Karels, John S. Quartermain, The Design and Implementation of the 4.4BSD Operating System (Addison Wesley, 1996; ISBN978-0-201-54979-9)
Marshall K. McKusick, George V. Neville-Neil, The Design and Implementation of the FreeBSD Operating System (Addison Wesley, August 2, 2004; ISBN978-0-201-70245-3)
Samuel J. Leffler, Marshall K. McKusick, Michael J. Karels, John S. Quarterman, The Design and Implementation of the 4.3BSD UNIX Operating System (Addison Wesley, November 1989; ISBN978-0-201-06196-3)
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