# Version 6 Unix > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Version_6_Unix > Markdown URL: https://mediated.wiki/source/Version_6_Unix.md > Source: https://en.wikipedia.org/wiki/Version_6_Unix > Source revision: 1340136155 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|6th Edition of Research Unix alias UNIX Time-Sharing System}} {{Infobox OS | name = Version 6 Unix | logo = | logo caption = | logo size = | logo alt = | screenshot = Version 6 Unix SIMH PDP11 Emulation KEN.png | caption = Version 6 [Unix](/source/Unix) for the [PDP-11](/source/PDP-11), running in the [SIMH](/source/SIMH) PDP-11 simulator | screenshot_size = | screenshot_alt = | collapsible = | version of = | developer = [AT&T Bell Laboratories](/source/AT%26T_Bell_Laboratories) | family = [Unix](/source/Unix) | working state = Historic | source model = Open source | released = {{Start date and age|1975|05}} | discontinued = | RTM date = | GA date = | latest release version = | latest release date = | latest preview version = | latest preview date = | marketing target = [Minicomputer](/source/Minicomputer)s | programmed in = [C](/source/C_(programming_language)), [assembly](/source/assembly_language) | language = [English](/source/English_language) | update model = | package manager = | supported platforms = [DEC](/source/Digital_Equipment_Corporation) [PDP-11](/source/PDP-11) | kernel type = | userland = | ui = [Command-line interface](/source/Command-line_interface) ([Thompson shell](/source/Thompson_shell)) | license = Originally [proprietary](/source/Proprietary_software) [commercial software](/source/commercial_software), now [free software](/source/free_software) under a [BSD License](/source/BSD_License) | preceded by = [Version 5 Unix](/source/Version_5_Unix) | succeeded by = [Version 7 Unix](/source/Version_7_Unix) | website = | support status = | other articles = | prog_language = }} '''Sixth Edition Unix''', also called '''Version 6 Unix''' or just '''V6''' is a version of the [Unix](/source/Unix) [operating system](/source/operating_system) first released in May 1975 and the first version of the Unix operating system to see wide release outside [Bell Labs](/source/Bell_Labs). Like its direct predecessor, the sixth edition targeted the [DEC](/source/Digital_Equipment_Corporation) [PDP-11](/source/PDP-11) family of [minicomputer](/source/minicomputer)s. It was superseded by [Version 7 Unix](/source/Version_7_Unix) in 1978/1979, although V6 systems remained in regular operation until at least 1985.{{cite journal|last1=Quarterman|first1=John S.|first2=Abraham|last2=Silberschatz |first3=James L. |last3=Peterson|title=4.2BSD and 4.3BSD as examples of the Unix system|journal=Computing Surveys|date=December 1985|volume=17|issue=4|pages=379–418|doi=10.1145/6041.6043|citeseerx = 10.1.1.117.9743|s2cid=5700897|quote=There are even some Version 6 systems still in regular operation.}} [AT&T Corporation](/source/AT%26T_Corporation) licensed [Version 5 Unix](/source/Version_5_Unix) to educational institutions only, but licensed Version 6 also to commercial users for $20,000, and it remained the most widely used version into the 1980s.{{cite news | url=https://archive.org/stream/byte-magazine-1983-10/1983_10_BYTE_08-10_UNIX#page/n133/mode/2up | title=The Unix Tutorial / Part 3: Unix in the Microcomputer Marketplace | work=BYTE | date=October 1983 | access-date=30 January 2015 | author=Fiedler, Ryan | pages=132}} An enhanced V6 was the basis of the first ever commercially sold Unix version, [INTERACTIVE](/source/Interactive_Systems_Corporation)'s IS/1. Bell's own [PWB/UNIX](/source/PWB%2FUNIX) 1.0 was also based on V6, where earlier (unreleased) versions were based on V4 and V5. [Whitesmiths](/source/Whitesmiths) produced and marketed a (binary-compatible) V6 clone under the name [Idris](/source/Idris_(operating_system)). ==Source code== [[File:Lions Commentary Unix.jpeg|thumb|[John Lions](/source/John_Lions)' original books, [source code](/source/source_code) and commentary]] [[File:Version 6 Unix SIMH PDP11 Emulation Source.png|thumb|Browsing through ''/usr/source'' on Version 6 [Unix](/source/Unix), running on [SIMH](/source/SIMH)]] {{main article|Lions' Commentary on UNIX 6th Edition, with Source Code}} V6 Unix was released as a distribution including the full [source code](/source/source_code). Since source code was available and the license was not explicit enough to forbid it, V6 was taken up as a teaching tool, notably by the [University of California, Berkeley](/source/University_of_California%2C_Berkeley), [Johns Hopkins University](/source/Johns_Hopkins_University) and the [University of New South Wales](/source/University_of_New_South_Wales) (UNSW). UC Berkeley distributed a set of add-on programs called the [First Berkeley Software Distribution](/source/Berkeley_Software_Distribution) or 1BSD, which later became a complete operating system distribution. UNSW professor [John Lions](/source/John_Lions)' famous [''Commentary on UNIX 6th Edition''](/source/Lions'_Commentary_on_UNIX_6th_Edition%2C_with_Source_Code) was an edited selection of the main parts of the kernel as implemented for a Digital PDP-11/40, and was the main source of kernel documentation for many early Unix developers. Due to license restrictions on later Unix versions, the book was mainly distributed by ''[samizdat](/source/samizdat)'' photo-copying. The source code for the original V6 Unix was later made available as [free software](/source/free_software) under a [BSD License](/source/BSD_License) from the [SCO Group](/source/SCO_Group).{{cite web|url=https://www.tuhs.org/Archive/Caldera-license.pdf|title=Letter from Caldera announcing the release of the source to older versions of UNIX as free software|access-date=2023-07-31|archive-date=2009-02-19|archive-url=https://web.archive.org/web/20090219220353/http://www.tuhs.org/Archive/Caldera-license.pdf|url-status=live}} ==Portability== Unix ran on a non-Digital computer for the first time when ported to Interdata hardware. Interdata maker [Perkin-Elmer](/source/Perkin-Elmer) became the first minicomputer company to support Unix.{{r|fiedler198310}} ===Interdata 7/32=== In 1977, Richard Miller and Ross Nealon, working under the supervision of professor Juris Reinfelds at [Wollongong University](/source/Wollongong_University), completed a port of V6 Unix to the [Interdata 7/32](/source/Interdata_7%2F32),{{cite web |url=http://www.uow.edu.au/content/groups/public/@web/@inf/@scsse/documents/doc/uow103747.pdf |title=The First Port of UNIX |author=Juris Reinfelds |archive-url=https://web.archive.org/web/20150704030021/http://www.uow.edu.au/content/groups/public/@web/@inf/@scsse/documents/doc/uow103747.pdf |archive-date=2015-07-04 |url-status=live}}{{cite web |url=http://bitsavers.org/bits/Interdata/32bit/unix/univWollongong_v6/miller.pdf |title=The First Unix Port |author=Richard Miller |archive-url=https://web.archive.org/web/20110815093105/http://www.bitsavers.org/bits/Interdata/32bit/unix/univWollongong_v6/miller.pdf |archive-date=2011-08-15 |url-status=live}} thus proving the portability of Unix and its new systems programming language [C](/source/C_(programming_language)) in practice. Their "Wollongong Interdata UNIX, Level 6" also included utilities developed at Wollongong, and later releases had features of V7, notably its [C](/source/C_(programming_language)) [compiler](/source/compiler). Wollongong Unix was the first ever port to a platform other than the PDP series of computers, proving that portable operating systems were indeed feasible, and that C was the language in which to write them. In 1980, this version was licensed to [The Wollongong Group](/source/The_Wollongong_Group) in Palo Alto that published it as Edition 7. ===Interdata 8/32=== Around the same time, a Bell Labs port to the Interdata 8/32 was completed, but not externally released. The goal of this port was to improve the portability of Unix more generally, as well to produce a portable version of the C compiler.{{cite journal |last1=Johnson |first1=S. C. |author-link1=Stephen C. Johnson |last2=Ritchie |first2=D. M. |author-link2=Dennis Ritchie |title=Portability of C Programs and the UNIX System |journal=Bell System Tech. J. |year=1978 |volume=57 |issue=6 |pages=2021–2048 |url=https://www.bell-labs.com/usr/dmr/www/portpap.pdf |access-date=4 June 2022 |doi=10.1002/j.1538-7305.1978.tb02141.x |s2cid=17510065 |archive-date=18 December 2021 |archive-url=https://web.archive.org/web/20211218212919/https://www.bell-labs.com/usr/dmr/www/portpap.pdf |url-status=live }} The resulting [Portable C Compiler](/source/Portable_C_Compiler) (PCC) was distributed with V7 and many later versions of Unix, and was used to produce the [UNIX/32V](/source/UNIX%2F32V) port to the [VAX](/source/VAX).{{cite web|author1=Thomas B. London|author2=John F. Reiser|year=1978|url=https://www.bell-labs.com/usr/dmr/www/otherports/32v.pdf|title=A Unix operating system for the DEC VAX-11/780 computer|access-date=2016-07-20|archive-date=2015-06-11|archive-url=https://web.archive.org/web/20150611114652/https://www.bell-labs.com/usr/dmr/www/otherports/32v.pdf|url-status=live}} ===IBM VM/370=== A third Unix portability project was completed at [Princeton, NJ](/source/Princeton%2C_New_Jersey) in 1976–1977, where the Unix kernel was adapted to run as a guest operating on IBM's [VM/370](/source/VM_(operating_system)) virtualization environment. This version became the nucleus of Amdahl's first internal UNIX offering. (see [Amdahl UTS](/source/Amdahl_UTS)) ==Variants and extensions== Bell Labs developed several variants of V6, including the stripped-down MINI-UNIX for low-end PDP-11 models, LSI-UNIX or LSX for the [LSI-11](/source/LSI-11), and the [real-time operating system](/source/real-time_operating_system) UNIX/RT, which merged V6 Unix and the earlier [MERT](/source/Multi-Environment_Real-Time) hypervisor.{{cite conference|last1=Bayer|first1=D. L.|last2=Lycklama|first2=H.|title=Proceedings of the fifth symposium on Operating systems principles - SOSP '75 |chapter-url=http://portal.acm.org/citation.cfm?id=806519|chapter=MERT - a multi-environment real-time operating system|conference=Fifth ACM Symposium on Operating Systems Principles|location=Austin, TX|year=1975|pages=33–42 |doi=10.1145/800213.806519|doi-access=free}} After AT&T decided the distribution by Bell Labs of a number of pre-V7 bug fixes would constitute support (disallowed by an antitrust settlement) a tape with the patchset was slipped to Lou Katz of [USENIX](/source/USENIX), who distributed them.{{cite journal|last=Toomey|first=Warren|title=The Strange Birth and Long Life of Unix|url=https://spectrum.ieee.org/the-strange-birth-and-long-life-of-unix|journal=[IEEE Spectrum](/source/IEEE_Spectrum)|date=December 2011|volume=48|issue=12|pages=34–55|publisher=[IEEE](/source/IEEE)|doi=10.1109/MSPEC.2011.6085780|s2cid=29893166|access-date=August 25, 2024|url-access=subscription}} The [University of Sydney](/source/University_of_Sydney) released the Australian Unix Share Accounting Method (AUSAM) in January 1978, a V6 variant with improved security and process accounting, in addition to the fifty fixes that leaked out of Bell Labs. There were several subsequent releases. [Interactive Systems Corporation](/source/Interactive_Systems_Corporation) released an enhanced [PDP-11](/source/PDP-11) version for office automation called [IS/1](/source/Interactive_Systems_Corporation).{{cite journal |first=R.D. |last=McCulloch |title=Putting it on the Line |url=https://books.google.com/books?id=oOvMdukBDRwC |journal=Oak Ridge National Laboratory Review |volume=14 |issue=3 |date=Summer 1981 |page=19 |access-date=2023-07-29 |archive-date=2023-07-31 |archive-url=https://web.archive.org/web/20230731175311/https://books.google.com/books?id=oOvMdukBDRwC |url-status=live }} In the [Eastern Bloc](/source/Eastern_Bloc), clones of V6 Unix appeared for local-built PDP-11 clones ([MNOS](/source/MNOS_(operating_system)), later augmented for partial compatibility with BSD Unix) and for the [Elektronika BK](/source/Elektronika_BK) personal computer ([BKUNIX](/source/BKUNIX), based on LSX). V6 was used for teaching at [MIT](/source/Massachusetts_Institute_of_Technology) in 2002 through 2006, and subsequently replaced by a simpler clone called [xv6](/source/xv6). ==See also== *[Ancient UNIX](/source/Ancient_UNIX) * {{anl|xv6}} ==References== {{Reflist}} ==External links== * [http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6 V6 source code] * [http://minnie.tuhs.org/cgi-bin/utree.pl?file=Interdata732 Wollongong Interdata UNIX source code] * [http://man.cat-v.org/unix-6th/ Unix V6 Manuals] – Web interface to the V6 manual pages. * [http://doc.cat-v.org/unix/v6/operating-systems-lecture-notes/v6/ Unix V6 documents, e.g. C Reference, and man pages] * [http://www.usenix.org/publications/library/proceedings/usenix98/invited_talks/miller.ps The First Unix Port]; Richard Miller's account of porting Unix to the Interdata 7/32 * [http://pdp11.aiju.de/ Unix v6 for PDP-11 online emulator] {{Bell Unix}} {{Unix-like}} Category:Bell Labs Unices Category:Discontinued operating systems Category:Unix history Category:Unix variants Category:Free software operating systems Category:1975 software --- Adapted from the Wikipedia article [Version 6 Unix](https://en.wikipedia.org/wiki/Version_6_Unix) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Version_6_Unix?action=history)). 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