Version 6 Unix

<h2 id="source-code">Source code</h2>

<p class="note">Main article: <a href="/facts/Lions%27_Commentary_on_UNIX_6th_Edition,_with_Source_Code/NnKKTM0T">Lions' Commentary on UNIX 6th Edition, with Source Code</a></p>
<p>V6 Unix was released as a distribution including the full <a href="/facts/Source_code/o9J6Jv23">source code</a>.  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 <a href="/facts/University_of_California,_Berkeley/MXVEjklr">University of California, Berkeley</a>, <a href="/facts/Johns_Hopkins_University/56US0mHw">Johns Hopkins University</a> and the <a href="/facts/University_of_New_South_Wales/h64vknzj">University of New South Wales</a> (UNSW).
</p><p>UC Berkeley distributed a set of add-on programs called the <a href="/facts/Berkeley_Software_Distribution/XQKcURrh">First Berkeley Software Distribution</a> or 1BSD, which later became a complete operating system distribution.
</p><p>UNSW professor <a href="/facts/John_Lions/Q0XdhKMh">John Lions</a>' famous <a href="/facts/Lions%27_Commentary_on_UNIX_6th_Edition,_with_Source_Code/NnKKTM0T"><i>Commentary on UNIX 6th Edition</i></a> 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 <i><a href="/facts/Samizdat/r7JkkRnp">samizdat</a></i> photo-copying.
</p><p>The source code for the original V6 Unix was later made available as <a href="/facts/Free_software/IaoVtJXn">free software</a> under a <a href="/facts/BSD_License/XLtmLp5x">BSD License</a> from the <a href="/facts/SCO_Group/uftSH8RP">SCO Group</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>
<h2 id="portability">Portability</h2>
<h3>Interdata 7/32</h3>
<p>In 1977, Richard Miller and Ross Nealon, working under the supervision of professor Juris Reinfelds at <a href="/facts/Wollongong_University/IFsWsava">Wollongong University</a>, completed a port of V6 Unix to the <a href="/facts/Interdata_7/32/RSEFj02y">Interdata 7/32</a>,<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a><a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> thus proving the portability of Unix and its new systems programming language <a href="/facts/C_(programming_language)/Ky2No763">C</a> in practice. Their "Wollongong Interdata UNIX, Level 6" also included utilities developed at Wollongong, and later releases had features of V7, notably its <a href="/facts/C_(programming_language)/Ky2No763">C</a> <a href="/facts/Compiler/WNfCDFJe">compiler</a>. 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 <a href="/facts/The_Wollongong_Group/9yH7TMAf">The Wollongong Group</a> in Palo Alto that published it as Edition 7.
</p>
<h3>Interdata 8/32</h3>
<p>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.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> The resulting <a href="/facts/Portable_C_Compiler/F1pVvjjt">Portable C Compiler</a> (PCC) was distributed with V7 and many later versions of Unix, and was used to produce the <a href="/facts/UNIX/32V/hKyF5cqS">UNIX/32V</a> port to the <a href="/facts/VAX/N3r13IHH">VAX</a>.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a>
</p>
<h3>IBM VM/370</h3>
<p>A third Unix portability project was completed at <a href="/facts/Princeton,_New_Jersey/fceTzdde">Princeton, NJ</a> in 1976–1977, where the Unix kernel was adapted to run as a guest operating on IBM's <a href="/facts/VM_(operating_system)/Ymu9SRtX">VM/370</a> virtualization environment.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> This version became the nucleus of Amdahl's first internal UNIX offering. (see <a href="/facts/Amdahl_UTS/mYJUvLf7">Amdahl UTS</a>)
</p>
<h2 id="variants-and-extensions">Variants and extensions</h2>
<p>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 <a href="/facts/LSI-11/9HkGUzFn">LSI-11</a>, and the <a href="/facts/Real-time_operating_system/IvUCFwCL">real-time operating system</a> UNIX/RT, which merged V6 Unix and the earlier <a href="/facts/Multi-Environment_Real-Time/Gc0eJXYc">MERT</a> hypervisor.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
</p><p>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 <a href="/facts/USENIX/2wz6aQwq">USENIX</a>, who distributed them.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a>
</p><p>The <a href="/facts/University_of_Sydney/AzENnAra">University of Sydney</a> 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.
</p><p><a href="/facts/Interactive_Systems_Corporation/uWkY8Xv7">Interactive Systems Corporation</a> released an enhanced <a href="/facts/PDP-11/9HkGUzFn">PDP-11</a> version for office automation called <a href="/facts/Interactive_Systems_Corporation/uWkY8Xv7">IS/1</a>.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a>
</p><p>In the <a href="/facts/Eastern_Bloc/12f32hA7">Eastern Bloc</a>, clones of V6 Unix appeared for local-built PDP-11 clones (<a href="/facts/MNOS_(operating_system)/7uJ6lazj">MNOS</a>, later augmented for partial compatibility with BSD Unix) and for the <a href="/facts/Elektronika_BK/X4E4c7rd">Elektronika BK</a> personal computer (BKUNIX, based on LSX).
</p><p>V6 was used for teaching at <a href="/facts/Massachusetts_Institute_of_Technology/Xk49vNA8">MIT</a> in 2002 through 2006, and subsequently replaced by a simpler clone called <a href="/facts/Xv6/pzV9lwfA">xv6</a>.
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Ancient_UNIX/PAqr4uUA">Ancient UNIX</a></li>
<li><a href="/facts/Xv6/pzV9lwfA">xv6</a> – Modern reimplementation of Sixth Edition Unix</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6">V6 source code</a></li>
<li><a href="http://minnie.tuhs.org/cgi-bin/utree.pl?file=Interdata732">Wollongong Interdata UNIX source code</a></li>
<li><a href="http://man.cat-v.org/unix-6th/">Unix V6 Manuals</a> – Web interface to the V6 manual pages.</li>
<li><a href="http://doc.cat-v.org/unix/v6/operating-systems-lecture-notes/v6/">Unix V6 documents, e.g. C Reference, and man pages</a></li>
<li><a href="http://www.usenix.org/publications/library/proceedings/usenix98/invited_talks/miller.ps">The First Unix Port</a>; Richard Miller's account of porting Unix to the Interdata 7/32</li>
<li><a href="http://pdp11.aiju.de/">Unix v6 for PDP-11 online emulator</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>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. CiteSeerX 10.1.1.117.9743. doi:10.1145/6041.6043. S2CID 5700897. There are even some Version 6 systems still in regular operation. <a href="/wiki/CiteSeerX_(identifier)" target="_blank">/wiki/CiteSeerX_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Fiedler, Ryan (October 1983). "The Unix Tutorial / Part 3: Unix in the Microcomputer Marketplace". BYTE. p. 132. Retrieved 30 January 2015. <a href="https://archive.org/stream/byte-magazine-1983-10/1983_10_BYTE_08-10_UNIX#page/n133/mode/2up" target="_blank">https://archive.org/stream/byte-magazine-1983-10/1983_10_BYTE_08-10_UNIX#page/n133/mode/2up</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>"Letter from Caldera announcing the release of the source to older versions of UNIX as free software" (PDF). Archived (PDF) from the original on 2009-02-19. Retrieved 2023-07-31. <a href="https://www.tuhs.org/Archive/Caldera-license.pdf" target="_blank">https://www.tuhs.org/Archive/Caldera-license.pdf</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Juris Reinfelds. "The First Port of UNIX" (PDF). Archived (PDF) from the original on 2015-07-04. <a href="http://www.uow.edu.au/content/groups/public/@web/@inf/@scsse/documents/doc/uow103747.pdf" target="_blank">http://www.uow.edu.au/content/groups/public/@web/@inf/@scsse/documents/doc/uow103747.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Richard Miller. "The First Unix Port" (PDF). Archived (PDF) from the original on 2011-08-15. <a href="http://bitsavers.org/bits/Interdata/32bit/unix/univWollongong_v6/miller.pdf" target="_blank">http://bitsavers.org/bits/Interdata/32bit/unix/univWollongong_v6/miller.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System" (PDF). Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. S2CID 17510065. Archived (PDF) from the original on 18 December 2021. Retrieved 4 June 2022. <a href="/wiki/Stephen_C._Johnson" target="_blank">/wiki/Stephen_C._Johnson</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Thomas B. London; John F. Reiser (1978). "A Unix operating system for the DEC VAX-11/780 computer" (PDF). Archived (PDF) from the original on 2015-06-11. Retrieved 2016-07-20. <a href="https://www.bell-labs.com/usr/dmr/www/otherports/32v.pdf" target="_blank">https://www.bell-labs.com/usr/dmr/www/otherports/32v.pdf</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Johnson, S. C.; Ritchie, D. M. (1978). "Portability of C Programs and the UNIX System" (PDF). Bell System Tech. J. 57 (6): 2021–2048. doi:10.1002/j.1538-7305.1978.tb02141.x. S2CID 17510065. Archived (PDF) from the original on 18 December 2021. Retrieved 4 June 2022. <a href="/wiki/Stephen_C._Johnson" target="_blank">/wiki/Stephen_C._Johnson</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Bayer, D. L.; Lycklama, H. (1975). "MERT - a multi-environment real-time operating system". Proceedings of the fifth symposium on Operating systems principles - SOSP '75. Fifth ACM Symposium on Operating Systems Principles. Austin, TX. pp. 33–42. doi:10.1145/800213.806519. <a href="http://portal.acm.org/citation.cfm?id=806519" target="_blank">http://portal.acm.org/citation.cfm?id=806519</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Toomey, Warren (December 2011). "The Strange Birth and Long Life of Unix". IEEE Spectrum. 48 (12). IEEE: 34–55. doi:10.1109/MSPEC.2011.6085780. S2CID 29893166. Retrieved August 25, 2024. <a href="https://spectrum.ieee.org/the-strange-birth-and-long-life-of-unix" target="_blank">https://spectrum.ieee.org/the-strange-birth-and-long-life-of-unix</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>McCulloch, R.D. (Summer 1981). "Putting it on the Line". Oak Ridge National Laboratory Review. 14 (3): 19. Archived from the original on 2023-07-31. Retrieved 2023-07-29. <a href="https://books.google.com/books?id=oOvMdukBDRwC" target="_blank">https://books.google.com/books?id=oOvMdukBDRwC</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
</ol>

Version 6 Unix open-in-new

Version 6 Unix