History of BSD operating systems

From DistroList
(Redirected from 4.4BSD)
OpenBSD DragonFly BSD
History of BSD operating systems


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.

Year Description

1974 The Unix operating system arrived at Berkeley at the request of computer science professor Bob Fabry.
  • A PDP-11/45 was bought to run the system. This machine was shared with the mathematics and statistics groups at Berkeley, so that Unix only ran on the machine 8 hours per day.
1975 A larger PDP-11/70 was installed at Berkeley using money from the Ingres database project.

Also 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.

1977 In 1977 Bill Joy started compiling the first Berkeley Software Distribution (1BSD).
1978 1BSD was released on 09/03/1978.


Year Description

05/1979 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.

A further feature was a networking package called Berknet, developed by Eric Schmidt as part of his master's thesis work, that could connect up to twenty-six computers and provided email and file transfer.

After 3BSD had come out for the VAX line of computers, new releases of 2BSD for the PDP-11 were still issued and distributed through USENIX; for example, 1982's 2.8.1BSD included a collection of fixes for performance problems in Version 7 Unix, and later releases contained ports of changes from the VAX-based releases of BSD back to the PDP-11 architecture.

  • 2.9BSD from 1983 included code from 4.1cBSD, and was the first release that was a full OS (a modified V7 Unix) rather than a set of applications and patches.
  • The most recent release, 2.11BSD, was released in 1991. In the 21st century, maintenance updates from volunteers continued: patch #481 was released on April 28, 2023.

2.11BSD CSRG was the last edition of the DEC PDP-11 line system. This release is maintained Steven Schultz with a series patchlevel. It is the release of 4.4BSD-Lite, and requires the original UNIX license.


Year Description

Ends 1979 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 by Berkeley graduate student Özalp Babaoğlu to include a virtual memory implementation, and a complete operating system including the new kernel, ports of the 2BSD utilities to the VAX, and the utilities from 32V was released as 3BSD at the end of 1979.

3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX (for Virtual Memory Unix), and BSD kernel images were normally called /vmunix until 4.4BSD.

The success of 3BSD was a major factor in the Defense Advanced Research Projects Agency'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.


Year Description


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. In a 1985 review of BSD releases, John Quarterman et al., wrote:

4BSD was the operating system of choice for VAXs from the beginning until the release of System III (1979–1982) [...] Most organizations would buy a 32V license and order 4BSD from Berkeley without ever bothering to get a 32V tape. Many installations inside the Bell System ran 4.1BSD (many still do, and many others run 4.2BSD).


Year Description


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.

Several tapes have turned up, all with a label that says 4.1BSD, yet differences between the tapes are present.

The software development that would lead from 4.1BSD to 4.2BSD was funded from sources including ARPA, Order Number 4031, Contract N00039-82-C-0235 which was in effect at least from November 15, 1981 through September 30, 1983.


Year Description

08/1983 4.2BSD (August 1983) would take over two years to implement and contained several major overhauls.

Before its official release came three intermediate versions:

  • 4.1a from April 1982 incorporated a modified version of BBN's preliminary TCP/IP implementation.
  • 4.1b from June 1982 included the new Berkeley Fast File System, implemented by Marshall Kirk McKusick.
  • 4.1c in April 1983 was an interim release during the last few months of 4.2BSD's development. Back at Bell Labs, 4.1cBSD became the basis of the 8th Edition of Research Unix, and a commercially supported version was available from mt Xinu.

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.

Apart from the Fast File System, several features from outside contributors were accepted, including disk quotas and job control. Sun Microsystems provided testing on its Motorola 68000 machines prior to release, improving portability of the system. Sun hardware support is plainly visible in the 4.1c BSD artifacts in the CSRG ISO.

The official 4.2BSD release came in August 1983. It was notable as the first version released after the 1982 departure of Bill Joy to co-found Sun Microsystems; Mike Karels 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.


Year Description

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.


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.

4.3BSD Networking Release 1 (Net/1)

Until then, all versions of BSD incorporated proprietary AT&T's 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.
Early 1990


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 explicitly moved towards POSIX compliance. Among the new features were an NFS implementation from the University of Guelph, a status key ("Ctrl-T") and support for the HP 9000 range of computers, originating in the University of Utah's "HPBSD" port.

4.3BSD Networking Release 2 (Net/2)

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, aka Network(ing) 2 or Net/2, a nearly complete operating system that was freely distributable.
Net/2 was the basis for two separate ports of BSD to the Intel 80386 architecture:
  • The free 386BSD by William Jolitz: 386BSD itself was short-lived, but became the initial code base of the NetBSD and FreeBSD projects that were started shortly thereafter.
  • The proprietary BSD/386 (later renamed BSD/OS) by Berkeley Software Design (BSDi): 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 April 1992 and led to an injunction on the distribution of Net/2 until the validity of USL's copyright claims on the source could be determined.
The lawsuit slowed development of the free software descendants of BSD for nearly two years while their legal status was in question, and as a result systems based on the Linux kernel, 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 or the GNU kernel had been available at the time, he probably would not have created Linux.


Year Description



In August 1992, 4.4BSD-Alpha was released.


In June 1993, 4.4BSD-Encumbered was released only to USL licensees.
The lawsuit was settled in January 1994, largely in Berkeley's favor. Of the 18,000 files in the Berkeley distribution, only three had to be removed and 70 modified to show USL copyright notices. A further condition of the settlement was that USL would not file further lawsuits against users and distributors of the Berkeley-owned code in the upcoming 4.4BSD release.


In March 1994, 4.4BSD-Lite was released that no longer require a USL source license and also contained many other changes over the original 4.4BSD-Encumbered release.

4.4BSD-Lite Release 2

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.


386BSD (also known as Jolix) 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.

386BSD ran on PC-compatible computer systems based on the 32-bit Intel 80386 ("i386") microprocessor, thus marking the first Unix on affordable home-class hardware.

Its innovations included role-based security, ring buffers, self-ordered configuration and modular kernel design.

Although 386BSD was short-lived, it served as the base for FreeBSD and NetBSD which began shortly afterwards.

History of 386BSD

386BSD was written mainly by Berkeley alumni Lynne Jolitz and William Jolitz. William had considerable experience with prior BSD releases while at the University of California, Berkeley (2.8 and 2.9BSD) and both contributed code developed at Symmetric Computer Systems during the 1980s, to Berkeley. William worked at Berkeley on porting 4.3BSD-Reno and later 4.3BSD Net/2 to the Intel 80386 for the university. 4.3BSD Net/2 was an incomplete non-operational release, with portions withheld by the University of California as encumbered.

The port began in 1989 and the first, incomplete traces of the port can be found in 4.3BSD Net/2 of 1991. The port was made possible as Keith Bostic, partly influenced by Richard Stallman, had started to remove proprietary AT&T out of BSD in 1988.

The port was first released to the public in March 1992 (version 0.0) - based on portions of the 4.3BSD Net/2 release coupled with additional code and in a much more usable version on July 14, 1992 (version 0.1).

386BSD proved popular, with it receiving 250,000 downloads from the FTP server it was hosted on. It was helped partly by the porting process with code being extensively documented in a 17-part series written by Lynne and William in Dr. Dobb's Journal beginning in January 1991.

FreeBSD and NetBSD

After the release of 386BSD 0.1, a group of users began collecting bug fixes and enhancements, releasing them as an unofficial patchkit. Due to differences of opinion between the Jolitzes and the patchkit maintainers over the future direction and release schedule of 386BSD, the maintainers of the patchkit founded the FreeBSD project in 1993 to continue their work. Around the same time, the NetBSD project was founded by a different group of 386BSD users, with the aim of unifying 386BSD with other strands of BSD development into one multi-platform system. Both projects continue to this day.

386BSD Release 0.0 was distributed in 1993 in tandem to the popular "Porting Unix to the 386" article series published in Dr. Dobb's Journal.

Release 0.1 quickly followed, enhanced with contributions throughout the globe.

386BSD Release 1.0, aka Jolix, was a break from earlier Berkeley UNIX systems through use of a modular architecture.

386BSD Release 2.0 built upon the modular framework to create self-healing components. Each release introduced novel mechanisms from role-based security to polymorphic protocols.

386BSD Releases
  • 386BSD 0.0, 12/03/1992, based on 4.3BSD Net/2.
  • 386BSD 0.1, 14/07/1992.
  • 386BSD 1.0 (Jolix), late 1994.
  • 386BSD 2.0 (Jolix), 05/08/2016.

Based on 386BSD & 4.4BSD-Lite

Brief history of BSD

Date Research Unix
& Operating System
1965-1969 Unnamed PDP-7 OS
May/1975 Version 6 Unix (V6)
09/03/1978 1BSD (an add-on of V6)
May/1979 2BSD
End 1979 3BSD
Nov/1980 4BSD
Jun/1981 4.1BSD
Aug/1983 4.2BSD
Jun/1986 4.3BSD
Jun/1988 4.3BSD-Tahoe
Jun/1989 4.3BSD Net 1
Early 1990 4.3BSD-Reno
Jun/1991 4.3BSD Net/2
12/03/1992 386BSD 0.0 (Jolix)
14/07/1992 386BSD 0.1 (Jolix)
19/04/1993 NetBSD 0.8
01/12/1993 FreeBSD 1.0
Mar/1994 4.4BSD-Lite
26/10/1994 NetBSD 1.0
1995 4.4BSD-Lite Release 2
22/11/1994 FreeBSD 2.0
01/09/1996 OpenBSD 2.0
16/10/1998 FreeBSD 3.0
03/04/2003 FreeBSD 4.8
12/07/2004 DragonFly BSD 1.0