History of Unix

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.^[1] 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^[2] – decided to redo the work, but on a much smaller scale.^[3]

In 1979, Ritchie described the group's vision for Unix:^[3]

What we wanted to preserve was not just a good environment in which to do programming, but a system around which a fellowship could form. We knew from experience that the essence of communal computing, as supplied by remote-access, time-shared machines, is not just to type programs into a terminal instead of a keypunch, but to encourage close communication.

1960s

Multics

In the late 1960s, Bell Labs was involved in a project with MIT and General Electric to develop a time-sharing system, called Multics, allowing multiple users to access a mainframe simultaneously. A key concept of the Multics system was the use of a single-level store. In this concept, there is no directly accessible file system. Instead, programs simply refer to data as if it is already in memory, if it is not, the virtual memory (VM) system loads it automatically. This means programs do not have to write code to explicitly read and write data from files into memory to manipulate it, the operating system does this all invisibly.^[4]

The Multics project began to bog down, and it became clear to the Bell team that the system was unlikely to deliver a working operating system in the near term, let alone a reasonably performant one.^[4] Bell Labs management ultimately withdrew from the project, and it seemed likely the company was going to end their lease on the very expensive GE 645 mainframe.^[5] Ken Thompson, a programmer in the Labs' computing research department, enjoyed the flexibility of Multics and began considering a new operating system that could run on less sophisticated machines.^[4]

New system

The basic concept was to use Multics' hierarchical file system but remove the single-level store.^[4] Thompson felt that the idea of a single-level store was ultimately a bad one as it treats all memory the same, whether program code or data, when in actual use they were treated very differently. Program code is rarely modified at runtime, may be placed in a read-only area of memory, and is randomly accessed due to branching. In contrast, data is almost always writable as runtime modification of file data is often the entire point of the program, and sequential access, as opposed to random, is a normal means of access. While his new system would require programmers to write their own routines to load and save data, that did not appear to be unreasonable.^[4]

Thompson began writing simulations of the new system under Multics, to understand the paging performance of the system. As this appeared promising, Thompson began writing the system for the GE 645, starting with a new custom

A key concept that was added during this period was made by Ritchie,[6] the concept of a device file. This was a file in the file system with the special ability to perform input/output operations. This allowed different devices to be supported simply by placing a file in an appropriate location in the file system. Read and write operations accessing these pseudo-files would perform operations on the device itself. This meant that devices were abstracted away through the file system, and programs could manipulate files no matter what sort of device they were on.^[10]

Douglas McIlroy then ported TMG compiler-compiler to PDP-7 assembly, creating the first high-level language running on Unix. Thompson used this tool to develop the first version of his B programming language.^[3]

1970s

The new operating system was initially without organizational backing, and also without a name. At this stage, the new operating system was a singletasking operating system,^[3] not a multitasking one such as Multics. The name Unics (Uniplexed Information and Computing Service, pronounced as "eunuchs"), a pun on Multics (Multiplexed Information and Computer Services), was initially suggested for the project in 1970. Brian Kernighan claims the coining for himself, and adds that "no one can remember" who came up with the final spelling Unix.^[11] Dennis Ritchie and Doug McIlroy also credit Kernighan.^[3][12]

When the Computing Sciences Research Center wanted to use Unix on a machine larger than the PDP-7, while Bell Labs Patent Department^[13] needed a word processor, Thompson and Ritchie added text processing capabilities to Unix and received funding for a PDP-11/45.^[14] For the first time in 1970, the Unix operating system was officially named and ran on the PDP-11. A text-formatting program called roff and a text editor were added. All three were written in PDP-11 assembly language. Bell Labs used this initial text-processing system, consisting of Unix, roff, and the editor, for text processing of patent applications. Roff soon evolved into troff, the first electronic publishing program with full typesetting capability.

As the system grew in complexity and the research team wanted more users, the need for a manual grew apparent. The UNIX Programmer's Manual was published on 3 November 1971; commands were documented in the "man page" format that is still used, offering terse reference information about usage as well as bugs in the software, and listing the authors of programs to channel questions to them.^[12]

After other Bell Labs departments purchased DEC PDP-11s, they also chose^[15] to run Unix instead of DEC's own operating system. By Version 4 it was widely used within the laboratory and a Unix Support Group was formed, helping the operating system survive by formalizing its distribution.^[14][12]

In 1973, Version 4 Unix was rewritten in the

The Unix operating system was first presented formally to the outside world at the 1973 Symposium on Operating Systems Principles, where Ritchie and Thompson delivered a paper.^[18] This led to requests for the system, but under a 1956 consent decree in settlement of an antitrust case, the Bell System (the parent organization of Bell Labs) was forbidden from entering any business other than "common carrier communications services", and was required to license any patents it had upon request.^[8] Unix could not, therefore, be turned into a product. Bell Labs instead shipped the system for the cost of media and shipping.^[8] Ken Thompson quietly began answering requests by shipping out tapes and disks, each accompanied by – according to legend – a note signed, "Love, Ken".^[19]

In 1973, AT&T released

Versions of the Unix system were determined by editions of its user manuals;[20] for example, "Fifth Edition UNIX" and "UNIX Version 5" have both been used to designate the same version. The Bell Labs developers did not think in terms of "releases" of the operating system, instead using a model of continuous development, and sometimes distributing tapes with patches (without AT&T lawyers' approval).^[8] Development expanded, adding the concept of pipes, which led to the development of a more modular code base, and quicker development cycles. Version 5, and especially Version 6, led to a plethora of different Unix versions both inside and outside Bell Labs, including PWB/UNIX and the first commercial Unix, IS/1.

Unix still only ran on DEC systems.

In May 1975, ARPA documented the benefits of the Unix time-sharing system which "presents several interesting capabilities" as an ARPA network mini-host in RFC 681.

In 1978, UNIX/32V was released for DEC's then new VAX system. By this time, over 600 machines were running Unix in some form. Version 7 Unix, the last version of Research Unix to be released widely, was released in 1979. In Version 7, the number of system calls was only around 50, although later Unix and Unix-like systems would add many more:^[23]

Version 7 of the Research UNIX System provided about 50 system calls,

SVR4 had around 120. The exact number of system calls varies depending on the operating system version. More recent systems have seen incredible growth in the number of supported system calls. Linux 3.2.0 has 380 system calls and FreeBSD

8.0 has over 450.

Bell developed multiple versions of Unix for internal use, such as

"Many of the (Version 10 Unix) medium-size tool programs (and their documentation) survived into the Plan 9 system, and are described in its programmer's manual and its own collection of papers."[33]

This research focus then shifted to the development of Plan 9 from Bell Labs, a new portable distributed operating system.

Because the company widely and inexpensively licensed Unix,^[34] by the early 1980s thousands of people used Unix at AT&T and elsewhere, and as computer science students moved from universities into companies they wanted to continue to use it. Observers began to see Unix as a potential universal operating system, suitable for all computers. Less than 20,000 lines of code – almost all in C – composed the Unix kernel as of 1983, and more than 75% was not machine-dependent. By that year Unix or a Unix-like system was available for at least 16 different processors and architectures from about 60 vendors; BYTE noted that computer companies "may support other [operating] systems, but a Unix implementation always happens to be available",^[14][20][35] and that DEC and IBM supported Unix as an alternative to their proprietary operating systems.^[36]

Microcomputer Unix became commercially available in 1980, when

AT&T announced UNIX System III – based on Version 7, and PWB – in 1981. Licensees could sell binary sublicenses for as little as US$100 (equivalent to $335.14 in 2023), which observers believed indicated that AT&T now viewed Unix as a commercial product.^[20] This also included support for the VAX. AT&T continued to issue licenses for older Unix versions. To end the confusion between all its differing internal versions, AT&T combined them into UNIX System V Release 1. This introduced a few features such as the vi editor and curses from the Berkeley Software Distribution of Unix developed at the University of California, Berkeley Computer Systems Research Group. This also included support for the Western Electric 3B series computers. AT&T provided support for System III and System V through the Unix Support Group (USG), and these systems were sometimes referred to as USG Unix.^{[citation needed]}

In 1983, the U.S. Department of Justice settled its second antitrust case against AT&T, causing the breakup of the Bell System. This relieved AT&T of the 1956 consent decree that had prevented the company from commercializing Unix. AT&T promptly introduced Unix System V into the market. The newly created competition nearly destroyed the long-term viability of Unix, because it stifled the free exchanging of source code and led to fragmentation and incompatibility.^[19] The GNU Project was founded in the same year by Richard Stallman.

Since the newer commercial UNIX licensing terms were not as favorable for academic use as the older versions of Unix, the Berkeley researchers continued to develop BSD as an alternative to UNIX System III and V. Many contributions to Unix first appeared in BSD releases, notably the C shell with job control (modelled on ITS). Perhaps the most important aspect of the BSD development effort was the addition of TCP/IP network code to the mainstream Unix kernel. The BSD effort produced several significant releases that contained network code: 4.1cBSD, 4.2BSD, 4.3BSD, 4.3BSD-Tahoe ("Tahoe" being the nickname of the Computer Consoles Inc. Power 6/32 architecture that was the first non-DEC release of the BSD kernel), Net/1, 4.3BSD-Reno (to match the "Tahoe" naming, and that the release was something of a gamble), Net/2, 4.4BSD, and 4.4BSD-lite. The network code found in these releases is the ancestor of much TCP/IP network code in use today, including code that was later released in AT&T System V UNIX and early versions of Microsoft Windows. The accompanying Berkeley sockets API is a de facto standard for networking APIs and has been copied on many platforms.

During this period, many observers expected that UNIX, with its portability, rich capabilities, and support from companies like DEC and IBM, was likely to become an industry-standard operating system for microcomputers.

Thompson and Ritchie were given the Turing Award in 1983 for their work on Unix.

In 1986,

Despite its academic reputation –

386/ix, and other Unix systems for the PC-compatible market competed with OS/2 in terms of networking, multiuser support, multitasking, and MS-DOS compatibility.^[41] The beginning in 1984 of the annual Unix Expo trade show in New York reflected the growing commercial presence of Unix.^[42]

During this time a number of vendors including Digital Equipment, Sun, Addamax and others began building trusted versions of UNIX for high security applications, mostly designed for military and law enforcement applications.

Standardization and the Unix wars

Main article: Unix wars

A problem that plagued Unix in this period was the multitude of implementations, based on either System V, BSD, or what Poul-Henning Kamp later described as a "more or less competently executed" combination of the two,^[43] usually with home-grown extensions to the base systems from AT&T or Berkeley.^[44] Xenix was effectively a third lineage, being based on the earlier System III.^[45] The rivalry between vendors was called the Unix wars; customers soon demanded standardization.^[45]

AT&T responded by issuing a standard, the System V Interface Definition (SVID, 1985), and required conformance for operating systems to be branded "System V". In 1984, several European computer vendors established the X/Open consortium with the goal of creating an open system specification based on Unix (and eventually the SVID).^[46] Yet another standardization effort was the

United States government for many of its own systems.^[47]

In the spring of 1988, AT&T took the standardization a step further. First, it collaborated with SCO to merge System V and Xenix into System V/386.

System V Release 4. AT&T and Sun, as UNIX International (UI), acted independently of X/Open and drew ire from other vendors, which started the Open Software Foundation to work on their own unified Unix, OSF/1, ushering in a new phase of the Unix wars.^[45]

1990s

The Unix wars continued into the 1990s, but turned out to be less of a threat than originally thought: AT&T and Sun went their own ways after System V.4, while OSF/1's schedule slipped behind.^[45] By 1993, most commercial vendors changed their variants of Unix to be based on System V with many BSD features added. The creation of the Common Open Software Environment (COSE) initiative that year, by the major players in Unix, marked the end of the most notorious phase of the Unix wars, and was followed by the merger of UI and OSF in 1994. The new combined entity retained the OSF name and stopped work on OSF/1. By that time the only vendor using it was Digital Equipment Corporation, which continued its own development, rebranding their product Digital UNIX in early 1995. POSIX became the unifying standard for Unix systems (and some other operating systems).^[45]

Meanwhile, the BSD world saw its own developments. The group at Berkeley moved its operating system toward POSIX compliance and released a stripped-down version of its networking code, supposedly without any code that was the property of AT&T. In 1991, a group of BSD developers (Donn Seeley, Mike Karels, Bill Jolitz, and Trent Hein) left the University of California to found Berkeley Software Design, Inc. (BSDi), which sold a fully functional commercial version of BSD Unix for the Intel platform, which they advertised as free of AT&T code. They ran into legal trouble when AT&T's Unix subsidiary sued BSDi for copyright infringement and various other charges in relation to BSD; subsequently, the University of California countersued.^[48] Shortly after it was founded, Bill Jolitz left BSDi to pursue distribution of 386BSD, the free software ancestor of FreeBSD, OpenBSD, and NetBSD.

In 1991, USL and Novell teamed up to develop a version of System 4 for i386 and i486 computers that would combine TCP/IP and Novell's IPX/SPX networking protocols, called the Destiny Project. They formed the Univel subsidiary as a jointly owned company to develop, market, and support the product, which was given the official name UnixWare (aka SRV4.2) and was sold as Univel UnixWare 1.0 that same year. Shortly after Univel released UnixWare 1.0 produced, AT&T sold USL and its share of Univel to Novell meaning Novell now owned all of AT&T's rights to Unix. Dennis Ritchie likened this sale to the Biblical story of Esau selling his birthright for the mess of pottage.^[49] Novell tried to use the fact that UnixWare combined both TCP/IP and NetWare networking technologies as a marketing tool against Windows NT, but their core markets suffered considerably. It also quickly settled the court battles with BSDi and Berkeley.^[48]

In 1993, Novell decided to transfer the UNIX trademark and certification rights to the X/Open Consortium.^[50] In 1996, X/Open merged with OSF, creating the Open Group. Various standards by the Open Group now define what is and what is not a UNIX operating system, notably the post-1998 Single UNIX Specification.

In 1993, Unix was used as a minor plot element in the blockbuster film Jurassic Park.^[51]

In 1995, the business of administering and supporting the existing UNIX licenses, plus rights to further develop the System V code base, were sold by Novell to the Santa Cruz Operation.^[52] Whether Novell also sold the copyrights would later become the subject of litigation (see below).

With the legal troubles between AT&T/Novell and the University of California over, the latter did two more releases of BSD before disbanding its Computer Systems Research Group in 1995. The BSD code lived on, however, in its free derivatives and in what Garfinkel et al. call a second generation of commercial Unix systems, based on BSD. The first exponent of these was BSDi's offering, popular at internet service providers but eventually not successful enough to sustain the company.^[53] The other main exponent would be Apple Computer.

In 1997, Apple sought a new foundation for its Macintosh operating system and chose NeXTSTEP, an operating system developed by NeXT. The core operating system, which was based on BSD and the Mach kernel, was renamed Darwin after Apple acquired it. The deployment of Darwin in Mac OS X makes it, according to a statement made by an Apple employee at a USENIX conference, the most widely used Unix-based system in the desktop computer market.^{[citation needed]}

Top500

Linux eclipsed Unix 1998–2017

Meanwhile, Unix got competition from the copyleft Linux kernel, a reimplementation of Unix from scratch, using parts of the GNU project that had been underway since the mid-1980s. Work on Linux began in 1991 by Linus Torvalds; in 1998, a confidential memo at Microsoft stated, "Linux is on track to eventually own the x86 UNIX market," and further predicted, "I believe that Linux – moreso than NT – will be the biggest threat to SCO in the near future."^[54]

2000s

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In 2000,

Caldera Systems, which later changed its name to The SCO Group

.

The bursting of the

Solaris, HP-UX, and AIX were still doing relatively well in the market, though SGI's IRIX persisted for quite some time. Of these, Solaris had the largest market share in 2005.^[55]

In 2003, the SCO Group started legal action against various users and vendors of Linux. SCO had alleged that Linux contained copyrighted Unix code now owned by the SCO Group. Other allegations included trade-secret violations by IBM, or contract violations by former Santa Cruz customers who had since converted to Linux. However, Novell disputed the SCO Group's claim to hold copyright on the UNIX source base. According to Novell, SCO (and hence the SCO Group) are effectively franchise operators for Novell, which also retained the core copyrights, veto rights over future licensing activities of SCO, and 95% of the licensing revenue. The SCO Group disagreed with this, and the dispute resulted in the SCO v. Novell lawsuit. On 10 August 2007, a major portion of the case was decided in Novell's favor (that Novell had the copyright to UNIX, and that the SCO Group had improperly kept money that was due to Novell). The court also ruled that "SCO is obligated to recognize Novell's waiver of SCO's claims against IBM and Sequent". After the ruling, Novell announced they have no interest in suing people over Unix and stated, "We don't believe there is Unix in Linux".^[56][57][58] SCO successfully got the 10th Circuit Court of Appeals to partially overturn this decision on 24 August 2009 which sent the lawsuit back to the courts for a jury trial.^[59][60][61]

On 30 March 2010, following a jury trial, Novell, and not The SCO Group, was "unanimously [found]" to be the owner of the UNIX and UnixWare copyrights.^[62] The SCO Group, through bankruptcy trustee Edward Cahn, decided to continue the lawsuit against IBM for causing a decline in SCO revenues.^[63] On March 1, 2016, SCO's lawsuit against IBM was dismissed with prejudice.

See also:

SCO-Linux controversies

In 2005, Sun Microsystems released the bulk of its Solaris system code (based on UNIX System V Release 4) into an open source project called OpenSolaris. New SunOS technologies, notably the ZFS file system, were first released as open source code via the OpenSolaris project. Soon afterwards, OpenSolaris spawned several non-Sun distributions. In 2010, after Oracle acquired Sun, OpenSolaris was officially discontinued, but the development of derivatives continued.

Since the early 2000s, Linux is the leading Unix-like operating system, with other variants of Unix (apart from macOS) having only a negligible market share (see Usage share of operating systems).

See also

• Comparison of operating systems
• The Unix Heritage Society
• History of the Berkeley Software Distribution
• List of Unix systems
• Timeline of operating systems
• Plan 9 from Bell Labs

References

Citations

1. ^ Stuart, Brian L. (2009). Principles of operating systems: design & applications. Boston, Massachusetts: Thompson Learning. p. 23.
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3. ^
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5. ^ ^{a b} Ritchie 1984, p. 1.
6. ^ ^{a b c d e f} Ritchie 1984, p. 2.
7. ^ "Doug McIlroy".
8. ^ ^{a b c d e} Salus, Peter H. (2005). The Daemon, the Gnu and the Penguin. Groklaw. "In August 1969, Ken Thompson's wife Bonnie took their year-old son on a trip to California to show off to their families. As a temporary bachelor, Ken had time to work. 'I allocated a week each to the operating system, the shell, the editor and the assembler [he told me]... and during the month she was gone, it was totally rewritten in a form that looked like an operating system'"
9. ^ Ritchie 1984, p. 3.
10. ^ Ritchie & Thompson 1978, p. 1909.
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27. ^ https://www.tuhs.org/cgi-bin/utree.pl?file=V8 ^{[bare URL]}
28. ^ ^{a b c}
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    • "Even so, the lesser-known editions within AT&T's Unix System Laboratories were the Eighth Edition in 1985, the Ninth Edition in 1986, and in 1989 the Tenth Edition"

    • https://www.theregister.com/2017/03/30/old_unix_source_code_opened_for_study/
29. ^ https://www.tuhs.org/cgi-bin/utree.pl?file=V9 ^{[bare URL]}
30. ^ "Unix Tenth Edition Manual". Archived from the original on 13 May 2021.
31. ^ https://www.tuhs.org/cgi-bin/utree.pl?file=V10 ^{[bare URL]}
32. ^
    • M. Douglas McIlroy A Research UNIX Reader: Annotated Excerpts from the Programmer’s Manual, 1971-1986
    • https://www.cs.dartmouth.edu/~doug/reader.pdf
    • https://archive.org/details/a_research_unix_reader
33. ^
    • https://web.archive.org/web/20210513190803/https://9p.io/10thEdMan/
    • https://web.archive.org/web/*/http://9p.io/7thEdMan/
    • https://web.archive.org/web/*/https://9p.io/cm/*
34. ^ Morgan, Chris (January 1982). "Of IBM, Operating Systems, and Rosetta Stones". BYTE. p. 6. Retrieved 19 October 2013.
35. ^ Tilson, Michael (October 1983). "Moving Unix to New Machines". BYTE. p. 266. Retrieved 31 January 2015.
36. ^ ^{a b c} Hinnant, David F. (August 1984). "Benchmarking UNIX Systems". BYTE. pp. 132–135, 400–409. Retrieved 23 February 2016.
37. ^ "UNIX". The Computer Chronicles. 1985.
38. ^ Howitt, Doran (10 December 1984). "Unix and the Single User". InfoWorld. p. 28. Retrieved 7 February 2015.
39. ^ Yates, Jean L. (October 1983). "Unix and the Standardization of Small Computer Systems". BYTE. pp. 160–166. Retrieved 30 January 2015.
40. ^ Kelleher 1986, pp. 37, 44.
41. ^ Jeff Tye; Lauren Black; Gregory Smith (10 July 1989). "Unix on the desktop: 80386-based Unix multiuser operating systems present an alternative to LANs". InfoWorld.
42. ^ Marshall, Martin (18 December 1989). "Hopes of Reunification Highlight Eventful Year for Unix Community". InfoWorld. p. 41.
43. S2CID 11656592
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44. ^ Kelleher 1986, p. 38.
45. ^
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48. ^
    ISBN 978-1-56592-582-3
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49. ^ "comp.unix.questions | Google Groups". Retrieved 9 November 2010.
50. ^ Chuck Karish. "The name UNIX is now the property of X/Open – comp.std.unix | Google Groups". Retrieved 9 November 2010.
51. ^ Brian Kernighan on the origins of Unix LWN.net. 2022.
52. ^ "HP, Novell and SCO To Deliver High-Volume UNIX OS With Advanced Network And Enterprise Services". Novell.com. 20 September 1995. Retrieved 9 November 2010.
53. ^ Garfinkel, Spafford & Schwartz 2003, p. 22.
54. ^ Vinod Valloppillil (11 August 1998). "Open Source Software: A (New?) Development Methodology". Retrieved 3 February 2014.
55. ^ Stephen (7 December 2005). "Itanium: A cautionary tale". Tech News. ZDNet. Archived from the original on 23 September 2006. Retrieved 4 October 2006. In the third quarter of this year, 7,845 Itanium servers were sold, according to research by Gartner. That compares with 62,776 machines with Sun Microsystems' UltraSparc, 31,648 with IBM's Power, and 9,147 with HP's PA-RISC.
56. ^ "Memorandum and Decision Order in SCO v. Novell". Groklaw.net. Retrieved 9 November 2010.
57. ^ "Tuxrocks.com" (PDF). Retrieved 6 January 2012.
58. ^ Novell Won't Pursue Unix Copyrights 15 August 2007
59. ^ "Appeal Ruling: 08-4217: The SCO Group v. Novell" (PDF). United States Court of Appeals, Tenth Circuit. 24 August 2009. 01018260169.
60. ^ Novell.com 24 August 2009
61. ^ Kravets, David (24 August 2009). "It's Baaaack … Appeals Court Resurrects SCO Lawsuit". Wired.
62. ^ "03/30/2010 – 846 – JURY VERDICT for Defendant Novell. (slm) (Entered: 03/30/2010)" (PDF). Retrieved 9 November 2010.
63. ^ Harvey, Tom (30 March 2010). "Decision in SCO-Novell case ripples beyond Utah". Salt Lake Tribune.

Bibliography

• Cooke, Daniel (May 1999). "Unix and Beyond: an Interview with Ken Thompson" (PDF). IEEE Computer. Vol. 32, no. 5. pp. 58–64.
  doi:10.1109/MC.1999.762801
  .
• Kelleher, Joanne (3 February 1986). "Corporate Unix: A system struggles to earn its stripes". Computerworld.
• Ritchie, Dennis (September 1979). The Evolution of the Unix Time-sharing System (PDF) (Technical report).
• Ritchie, Dennis; Thompson, Ken (July–August 1978). "The UNIX Time-Sharing System". Bell System Technical Journal. 57 (6): 1905–1929.
  doi:10.1002/j.1538-7305.1978.tb02136.x
  .
• "The Creation of the UNIX* Operating System: The famous PDP-7 comes to the rescue". Bell-labs.com. Archived from the original on 2 April 2014. Retrieved 20 April 2015.
• "The History of Unix". BYTE. August 1983. p. 188. Retrieved 31 January 2015.

Further reading

Books

• ISBN 978-1695978553
  .
• ISBN 978-0-201-54777-1
  .

Television

• "UNIX". The Computer Chronicles. 1985.
• "Unix". The Computer Chronicles. 1989.

Talks

• Ken Thompson (2019). "VCF East 2019 -- Brian Kernighan interviews Ken Thompson" (Interview).
• Dr Marshall Kirk McKusick (2006). History of the Berkeley Software Distributions (three one-hour lectures).

External links

Look up Unix in Wiktionary, the free dictionary.

• The UNIX System, at The Open Group.
• The Creation of the UNIX Operating System
• The Unix Heritage Society
  • The Unix Tree: files from historic releases
• History of Unix at
  Curlie
• The Unix 1st Edition Manuals.
• 1982 film about Unix featuring Dennis Ritchie, Ken Thompson, Brian Kernighan, Alfred Aho, and more
• Video: VCF East 2019 -- Brian Kernighan interviews Ken Thompson
• A History of UNIX before Berkeley: UNIX Evolution: 1975-1984
• audio bsdtalk170 - Marshall Kirk McKusick at DCBSDCon -- on history of tcp/ip (in BSD) -- abridgement of the three lectures on the history of BSD.
• UNIX History timeline diagram with 150 versions over 50 years diagram
• Unix History Repository on GitHub