Editing Version 7 Unix

{{Short description|1979 minicomputer operating system}}
{{about|the 1979 Research Unix Operating System|the Single Unix Specification trademark|UNIX V7}}
{{Infobox OS
| name = Version 7 Unix<!-- Name of program or distribution -->
| logo = <!-- filename only (no wikilink, no Image:/File:) -->
| logo caption = 
| logo size = 
| logo alt = 
| screenshot = Version 7 Unix SIMH PDP11 Emulation DMR.png<!-- filename only (no wikilink, no Image:/File:) -->
| caption = Version 7 [[Unix]] for the [[PDP-11]], running in the [[SIMH]] PDP-11 simulator
| screenshot_size = 
| screenshot_alt = 
| collapsible = 
| version of = <!-- For articles about releases of operating systems ONLY -->
| developer = [[AT&T Bell Laboratories]]<!-- Name of main developer or sponsor-->
| family = [[Unix]]<!-- "Unix-like" or "Microsoft Windows" -->
| working state = Historic<!-- "Current", "Discontinued" (operating systems), or "No longer supported" (releases) -->
| source model = Originally [[proprietary software]], now [[open source]]
| released = {{Start date and age|1979}}
| discontinued = <!-- DON'T use this for articles about releases of operating systems -->
| RTM date = <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} ONLY for articles about OS releases -->
| GA date = <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} ONLY for articles about OS releases -->
| latest release version = 
| latest release date = 
| latest preview version = 
| latest preview date = <!-- {{Start date and age|YYYY|MM|DD|df=yes/no}} -->
| marketing target = [[Minicomputer]]s
| programmed in = [[C (programming language)|C]], [[assembly language|assembly]]
| language = [[English language|English]]<!-- Supported human languages (English, French, Italian, Arabic, ...) -->
| update model = <!-- APT, Windows Update, etc. -->
| package manager = <!-- dpkg, rpm, Windows installer, etc. -->
| supported platforms = [[Digital Equipment Corporation|DEC]] [[PDP-11]]<!-- IA-32, x64, Itanium, ARM, etc. -->, [[VAX]] ([[UNIX/32V|32v]]), [[x86]]
| kernel type = [[Monolithic kernel|Monolithic]]
| userland = 
| ui = [[Command-line interface]] ([[Bourne shell]])
| license = Originally [[Proprietary software|proprietary]] [[commercial software]], now [[free software]] under a [[BSD-license|BSD-like]] license
| preceded by = [[Version 6 Unix]]
| succeeded by = [[Version 8 Unix]]
| website = <!-- {{URL|www.example.org}} -->
| support status = <!-- For articles about releases of operating systems ONLY -->
| other articles = 
}}
'''Version 7 Unix''', also called '''Seventh Edition Unix''', '''Version 7''' or just '''V7''', was an important early release of the [[Unix]] [[operating system]].  V7, released in 1979, was the last [[Bell Laboratories]] release to see widespread distribution before the commercialization of Unix by [[AT&T Corporation]] in the early 1980s.  V7 was originally developed for [[Digital Equipment Corporation]]'s [[PDP-11]] minicomputers and was later ported to other platforms.

==Overview==
Unix versions from Bell Labs were designated by the edition of the user's manual with which they were accompanied. Released in 1979, the Seventh Edition was preceded by [[Version 6 Unix|Sixth Edition]], which was the first version licensed to commercial users.<ref name="fiedler198310">{{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=2018-09-11 |issn=0360-5280 |oclc=854802500 |first=David |last=Fiedler | pages=132}}</ref> Development of the [[Research Unix]] line continued with the [[Version 8 Unix|Eighth Edition]], which incorporated development from [[Berkeley Software Distribution|4.1BSD]], through the Tenth Edition, after which the Bell Labs researchers concentrated on developing [[Plan 9 from Bell Labs|Plan 9]].

V7 was the first readily [[porting|portable]] version of Unix. As this was the era of [[minicomputer]]s, with their many architectural variations, and also the beginning of the market for 16-bit microprocessors, many ports were completed within the first few years of its release. The first [[Sun Microsystems|Sun]] workstations (then based on the [[Motorola 68000]]) ran a V7 port by [[UniSoft]];<ref>{{cite web|url=http://www.sunhelp.org/faq/sunref1.html|title=The Sun Hardware Reference, Part II|author=James W. Birdsall|quote=Sun-1's were the very first models ever produced by Sun. The earliest ran Unisoft V7 UNIX; SunOS 1.x was introduced later.}}</ref> the first version of [[Xenix]] for the [[Intel 8086]] was derived from V7 and [[Onyx Systems]] soon produced a [[Zilog]] [[Zilog Z8000|Z8000]] computer running V7. The [[VAX]] port of V7, called [[UNIX/32V]], was the direct ancestor of the popular [[Berkeley Software Distribution|4BSD family]] of Unix systems.

The group at the [[University of Wollongong]] that had [[Wollongong Unix|ported V6]] to the [[Interdata 7/32]] ported V7 to that machine as well. [[Interdata]] sold the port as Edition VII, making it the first commercial UNIX offering.{{citation needed|date=December 2012}}

[[Digital Equipment Corporation|DEC]] distributed their own PDP-11 version of V7, called '''V7M''' (for modified).  V7M, developed by DEC's original Unix Engineering Group (UEG), contained many enhancements to the kernel for the PDP-11 line of computers including significantly improved hardware error recovery and many additional device drivers.<ref>{{cite web |last=Canter |first=Fred|title=V7M 2.1 SPD|url=http://bitsavers.org/pdf/dec/pdp11/ultrix-11/Unix_V7M_Release_2.1_Software_Description_Sep81.pdf|publisher=Digital Equipment Corp |access-date=7 January 2012}}</ref> UEG evolved into the group that later developed [[Ultrix]].

==Reception==
Due to its power yet elegant simplicity, many old-time Unix users remember V7 as the pinnacle of Unix development and have dubbed it "the last true Unix", an improvement over all preceding and following Unices. At the time of its release, though, its greatly extended feature set came at the expense of a decrease in performance compared to V6, which was to be corrected largely by the user community.<ref name="penguin">{{cite book |first=Peter H. |last=Salus |author-link=Peter H. Salus |title=The Daemon, the Gnu and the Penguin |url=http://www.groklaw.net/article.php?story=20050502114023686 |publisher=[[Groklaw]] |year=2005}}</ref>

The number of [[system call]]s in Version 7 was only around 50, while later Unix and Unix-like systems continued to add many more:<ref>Stevens, W Richard. Rago, Stephen A. ''Advanced Programming in the UNIX Environment, 3rd Edition.'' 2013. p. 21</ref>

{{blockquote|Version 7 of the Research UNIX System provided about 50 system calls, [[4.4BSD]] provided about 110, and [[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]] 5.15.0 has 449 system calls and [[FreeBSD]] 8.0 has over 450.}}

==Released as free software==
[[File:Pdp11-unixv7.png|thumb|Screenshot of a PDP-11 booting Version 7 Unix in a simulator.]]
In 2002, [[Caldera International]] released<ref>[http://slashdot.org/articles/02/01/24/0146248.shtml Caldera releases original unices under BSD license] on [[slashdot.org]] (2002)</ref> V7 as [[free and open source software|FOSS]] under a [[Permissive license|permissive]] [[BSD-license|BSD-like]] [[software license]].<ref>{{cite web |url=http://www.lemis.com/grog/UNIX/|publisher=lemis.com |title=UNIX is free! |date=2002-01-24}}</ref><ref name="Caldera-license.pdf">{{cite web|url=http://www.tuhs.org/Archive/Caldera-license.pdf |archive-url=https://web.archive.org/web/20090219220353/http://www.tuhs.org/Archive/Caldera-license.pdf|archive-date=February 19, 2009 |title=Dear Unix enthusiasts |last=Broderick |first=Bill |date=January 23, 2002 |publisher=[[Caldera International]]}}</ref><ref>{{cite web|url=http://www.linuxdevcenter.com/pub/a/linux/2002/02/28/caldera.html |publisher=[[O'Reilly Media]] |work=Linuxdevcenter |title=Why Caldera Released Unix: A Brief History |first=Ian F. |last=Darwin |date=2002-02-03 |access-date=2016-01-19 |archive-url=https://web.archive.org/web/20160126012127/http://www.linuxdevcenter.com/pub/a/linux/2002/02/28/caldera.html |archive-date=2016-01-26}}</ref>

Bootable images for V7 can still be [http://ftp.fibranet.cat/UnixArchive/Distributions/Boot_Images/ downloaded] today, and can be run on modern hosts using PDP-11 emulators such as [[SIMH]].

An [[x86]] port has been developed by Nordier & Associates.<ref>https://www.nordier.com/#v7x86 Robert Nordier - UNIX v7/x86</ref>

[[Paul Allen]] maintained{{when|date=August 2019}} several publicly accessible historic computer systems, including a PDP-11/70 running Unix Version 7.

==New features in Version 7==
Many new features were introduced in Version 7.
*Programming tools: [[lex programming tool|lex]], [[lint (software)|lint]], and [[make (software)|make]].

The [[Portable C Compiler]] (pcc) was provided along with the earlier, PDP-11-specific, C compiler by [[Dennis Ritchie|Ritchie]].

These first appeared in the Research Unix lineage in Version 7, although early versions of some of them had already been picked up by [[PWB/UNIX]].<ref name="reader">{{cite tech report |author-link=Doug McIlroy |first=M. Douglas |last=McIlroy |year=1987 |url=http://www.cs.dartmouth.edu/~doug/reader.pdf |title=A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 |number=CSTR 139 |publisher=Bell Labs |access-date=2018-07-22}}</ref>

*New commands: the [[Bourne shell]],{{r|reader}} at, [[awk]], calendar, [[F77#FORTRAN 77|f77]], [[fortune (Unix)|fortune]], [[tar (computing)|tar]] (replacing the tp command), touch
*Networking support, in the form of [[uucp]] and [[Datakit]]<ref name="reader"/>
*New [[system call]]s: access, acct, alarm, [[chroot]] (originally used to test the V7 distribution during preparation{{Citation needed|date=March 2014}}), exece, [[ioctl]], lseek (previously only 24-bit offsets were available), [[umask]], utime
*New library calls: The new [[stdio.h|stdio]] routines,{{r|fiedler198310}} [[malloc]], getenv, popen/system
*[[Environment variable]]s
*A maximum file size of just over one [[gigabyte]],{{r|fiedler198310}} through a system of indirect addressing<ref>{{cite journal |last=Thompson |first=Ken |author-link=Ken Thompson |title=UNIX Implementation |journal=Bell System Technical Journal |volume=57 |issue=6 |year=1978 |pages=1931–1946 |doi=10.1002/j.1538-7305.1978.tb02137.x|s2cid=19423060 }}</ref>

===Multiplexed files===
A feature that did not survive long was a second way (besides pipes) to do [[inter-process communication]]: multiplexed files. A process could create a special type of file with the <code>mpx</code> system call; other processes could then open this file to get a "channel", denoted by a [[file descriptor]], which could be used to communicate with the process that created the multiplexed file.<ref>{{man|2|mpx|v7}}</ref> Mpx files were considered experimental, not enabled in the default kernel,<ref>{{man|1|mkconf|v7}}</ref> and disappeared from later versions, which offered [[Berkeley sockets|sockets]] (BSD) or [[CB UNIX]]'s IPC facilities (System V) instead<ref>{{cite tech report |last1=Leffler |first1=Samuel J. |last2=Fabry |first2=Robert S. |last3=Joy |first3=William N. |author-link3=Bill Joy |last4=Lapsley |first4=Phil |last5=Miller |first5=Steve |last6=Torek |first6=Chris |year=1986 |title=An Advanced 4.3 BSD Interprocess Communication Tutorial |publisher=Computer Systems Research Group, University of California, Berkeley}}</ref> (although mpx files were still present in 4.1BSD<ref>{{cite journal |first=Dennis M. |last=Ritchie |title=A Stream Input-Output System |publisher=AT&T |journal=AT&T Bell Laboratories Technical Journal |volume=63 |issue=8 |pages=1897–1910 |year=1984 |author-link=Dennis Ritchie |doi=10.1002/j.1538-7305.1984.tb00071.x |citeseerx=10.1.1.48.3730|s2cid=33497669 }}</ref>).

==See also==
*[[Version 6 Unix]]
*[[Seventh Edition Unix terminal interface]]
*[[Ancient UNIX]]

==References==
{{Reflist|30em}}

==External links==
* [https://plan9.io/7thEdMan/ Unix Seventh Edition manual] at [[Plan 9 from Bell Labs]]
* [http://minnie.tuhs.org/UnixTree/V7/ Browsable source code] at [[The Unix Heritage Society]]
* [http://minnie.tuhs.org/PUPS/ PDP Unix Preservation Society] at [[The Unix Heritage Society]]
* [https://www.tuhs.org/archive_sites.html ''Unix Archive'' Sites List] at [[The Unix Heritage Society]]

{{Bell Unix}}
{{Unix-like}}

[[Category:Bell Labs Unices]]
[[Category:Berkeley Software Distribution]]
[[Category:Discontinued operating systems]]
[[Category:Free software operating systems]]
[[Category:1979 software]]