According to ABBREVIATIONFINDER.ORG, BSD stands for Berkeley Software Distribution. It is used to identify an Operating System derived from the Unix system born from the contributions made to that system by the University of California at Berkeley.
In the early years of the Unix system, its creators, the Bell Laboratories of the AT&T company, authorized the University of California at Berkeley and other universities to use the source code and adapt it to their needs. During the 1970s and 1980s Berkeley used the system for its research on operating systems. When AT&T withdrew the permission to use the university for commercial reasons, the university promoted the creation of a version inspired by the Unix system using the contributions they had made, then allowing its distribution for academic purposes and after some time reducing to the minimum restrictions regarding its copying, distribution or modification.
The beginnings with PDP-11
The first distributions of Unix from Bell Labs in the 1970s included the source code of the operating system, allowing university developers to modify and extend Unix. Berkeley’s first Unix system was the PDP-11, which was installed in 1974, and has since been used by the computer science department for research. Other universities became interested in Berkeley software, and so in 1977 Bill Joy, then a graduate student at Berkeley, recorded and shipped tapes from the first Berkeley Software Distribution (BSD).
BSD 1 was an add-on to the Unix sixth edition, rather than a complete operating system. It was mainly composed of a Pascal compiler and a text editor created by Joy himself called “ex”.
BSD 2 was released in 1978, it included updated versions of 1BSD and also two new programs created by Joy that survive on Unix systems to this day. The vi text editor and the C shell. The following versions of BSD 2 contained adaptations of the BSD distributions based on the VAXarchitecture, to make them compatible with the PDP-11 architecture.
BSD 2.9 since 1983 includes code from BDS 4.1c and was the first distribution to be considered a full operating system (A modification of Unix 7). The most recent distribution, BSD 2.11 was released in 1992, and with the help of volunteers it continued to be updated until 2003.
In 1978 a VAX computer was installed in Berkeley, but the adaptation of Unix to the VAX architecture, UNIX / 32V, did not take advantage of the virtual memory capacity of this architecture. The 32V kernel was practically rewritten by Berkeley students to take advantage of virtual memory, and finally, in late 1979, 3BSD was released, which included a new kernel, 2BSD adaptations to the VAX architecture, and 32V utilities. . BSD 3 was also called Virtual VAX / UNIX or VMUNIX (Virtual Memory Unix), and the BSD / vmunix kernel images up to BSD 4.4.
The achievement of BSD 3 was a decisive factor for the (Defense Advanced Projects Agency) (DARPA), which wanted to develop a standard Unix platform for its research in the VLSI project, to found Berkeley’s Computer System Research Group (CSRG).
Launched in November 1980, it offered many improvements over BSD 3, including especially in the control work of the previous version of csh, delivermail (the present sendmail), “trusted” signals, and the Curses programming library.
BSD 4.1, released in June 1981, was the answer to criticism of BSD compared to the dominant operating system for the VAX architecture, the VMS. BSD 4.1 was improved by Bill Joy until it achieved the same performance as VMS. The distribution was originally to be called BSD 5, but was changed to avoid potential confusion with the release of AT & T’s Unix System V.
BSD 4.2 it took two years to implement, and contained great improvements. Before its official release appeared three intermediate versions 4.1a incorporated a modified version of the preliminary implementation of BBN’s TCP / IP. 4.1b included the new Berkeley Fast File System, implemented by Marshall Kira McKusick, and 4.1c was an internal version that was used during the last months of BSD 4.2 development. The official distribution of BSD 4.2 was released in August 1983. It was the first distribution of BSD since Bill Joy left and co-founded Sun Microsystems. Mike Karels and Marshall Kira MacKusick took control of the project from that moment on. In a note, the debut of the BSD demon and mascot is highlighted, by means of a drawing by McKusick that appeared on the covers of the printed manuals distributed by USENIX.
BSD4.3 It was released in June 1986. Its main changes were the improvement of many of the new contributions made by BSD 4.2 that were not improved as was the BSD4.3 code. Before its release, the TCP / IP implementation contained in BSD diverged considerably from the official one made by BBN. That is why after many tests carried out by DARPA, it concluded that the version included in BSD 4.2 was superior to the new one, and that therefore it should be kept in the new distribution. After version 4.3, it was determined that future versions should be built based on another architecture different from the already old VAX. At that time, Power 6/32, developed by Computer Consoles Inc, seemed like a platform with more future, although it was abandoned by its developers soon after. Nevertheless,
Up to this point, all versions of BSD had incorporated AT&T proprietary code, which required licenses for their use. These became very expensive, so many external entities expressed their interest in a separate distribution of the proprietary network code developed by AT&T, so that it would not be subject to the payment of those licenses. This was achieved with Network Tape 1 (Net / 1), released in 1989 and created without AT&T proprietary code that was freely distributed on the terms of the permissive BSD license.
BSD 4.3-Reno was released in 1990. It was a version for internal use used during the build of BSD 4.4. This distribution was clearly moving towards POSIX compatibility, and, according to some, away from the BSD philosophy, since POSIX is based on the V.
Net / 2 and legal problems
After Net / 1, Keith Bostic proposed that more non-AT&T BSD sections be released with the same Net / 1 license. With this in mind, he started a project that aimed to implement many of the standard Unix utilities without AT&T code. Within 18 months, all of AT & T’s proprietary utilities were replaced, and only a few proprietary files remained in the kernel. These files were finally eliminated, giving rise to Net / 2, practically a complete operating system and also freely distributable.
Net / 2 was the basis for two independent BSD adaptations for Intel’s 80386 architecture, William Jolliz’s 386BSD and the proprietary BSD / 386 (later renamed BSD / OS) from Berkeley Software Design (BSDi). 386BSD was short-lived, but it was the starting point for FreeBSD and NetBSD.
BSDi soon had a legal problem with AT&T, owners of the rights to System V and the Unix brand. The lawsuit was filed in 1992, under the injunction not to distribute Net / 2 until the validity of the lawsuits could be determined..
The lawsuit slowed the development of the free descendants of BSD for about two years during which their legal status was in question, and because of this, the systems based more relevance. Linux and 386BSD started development at the same time, and even Linus Torvalds said that if there had been a free Unix-based operating system for the 386 architecture, he probably wouldn’t have created Linux. Although it is debatable what effect it would have had in the software field, it is certain that it would have been substantial.
4.4 BSD and descendants
The lawsuit ended in January 1994 in favor of Berkeley. Of the 18,000 files contained in the distribution, only three were removed and 70 modified to show AT & T’s proprietary rights.
In June 1994 BSD 4.4 was released with two versions: a freely distributable one called BSD 4.4-Lite, without proprietary code, and BSD 4.4-Encumbered, only for AT&T dealers.
The last distribution created by Berkeley was BSD 4.4-Lite Release 2, released in 1995, after the CSRG was dissolved and the development of BSD at Berkeley was ceased. Since then, many BSD 4.4-based distributions have appeared, such as FreeBSD, OpenBSD, and NetBSD.
Furthermore, the permissive BSD license has allowed other operating systems, both free and proprietary, to incorporate BSD code. For example, Microsoft Windows has used BSD-derived code in its TCP / IP implementation, and uses recompiled versions of the BSD command line for networking tools. Also Darwin, the system on which Mac OS X, Apple’s operating system, is built, is partly derived from FreeBSD 5. Other commercial Unix-based systems such as Solaris also use BSD code.
Some operating systems descendants of the system developed by Berkeley are SunOS, FreeBSD, NetBSD, OpenBSD and Mac OS X. BSD has also made great contributions in the field of operating systems in general, such as:
- paged virtual memory handling on demand
- job control
- the Fast FileSystem
- the TCP / IP protocol (almost all TCP implementations are derived from 4BSD-Lite)
- 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; ISBN 978-0-201-06196-3)
- Marshall K. McKusick, Keith Bostic, Michael J. Karels, John S. Quartermain, The Design and Implementation of the 4.4BSD Operating System (Addison Wesley, 1996; ISBN 978-0-201-54979-9)
- Marshall K. McKusick, George V. Neville-Neil, The Design and Implementation of the FreeBSD Operating System (Addison Wesley, August 2, 2004; ISBN 978-0-201-70245-3)