Editing UNIX System V (section)

== Releases ==
[[File:Teletype_DMD_5620.jpg|thumb|DMD 5620 terminal, based on the [[Blit (computer terminal)|''Blit'']], connected to a SVR3 host and showing the ''Layers'' interface]]

=== SVR1 ===
System V, known inside Bell Labs as Unix 5.0, succeeded AT&T's previous commercial Unix called [[UNIX System III|System III]] in January, 1983.<ref name="levenez">{{cite web
| url         = http://www.levenez.com/unix/
| title       = Unix History (Unix Timeline)
| first       = Éric
| last        = Lévénez
| archive-url  = https://web.archive.org/web/20020802080343/http://www.levenez.com/unix/
| archive-date = 2002-08-02
| url-status    = live
| access-date  = 2010-12-29
}}</ref>
Unix 4.0 was never released externally, which would have been designated as System IV.<ref>{{cite book |title=Overview of the XENIX 286 Operating System |publisher=Intel Corporation |date= November 1984 |url=http://bitsavers.trailing-edge.com/pdf/intel/system3xx/xenix-286/174385-001_Overview_of_the_XENIX_286_Operating_System_Nov84.pdf |page=1.10 |quote=There was no System IV.}}</ref><ref>{{cite newsgroup
  | title = UNIX History
  | author = Dale Dejager
  | date = 1984-01-16
  | newsgroup = net.unix
  | url = http://groups.google.com/group/net.unix/msg/b80689d4b3bff13f?dmode=source
}}</ref><ref>{{cite book |title=Modern Operating Systems |last=Tanenbaum |first=Andrew S. |quote=Whatever happened to System IV is one of the great unsolved mysteries of computer science. |location=Upper Saddle River, NJ |publisher=Prentice Hall |edition=2nd |year=2001 |page=[https://archive.org/details/modernoperatings00tane/page/675 675] |isbn=0-13-031358-0 |url=https://archive.org/details/modernoperatings00tane/page/675 }}</ref>
This first release of System V (called System V.0, System V Release 1, or SVR1) was developed by AT&T's UNIX Support Group (USG) and based on the Bell Labs internal USG UNIX 5.0.

System V also included features such as the [[Vi (text editor)|vi]] editor and [[curses (programming library)|curses]] from 4.1 BSD, developed at the [[University of California, Berkeley]]; it also improved performance by adding buffer and [[inode]] caches. It also added support for [[inter-process communication]] using messages, [[semaphore (programming)|semaphore]]s, and [[shared memory (interprocess communication)|shared memory]], developed earlier for the Bell-internal [[CB UNIX]].<ref name="kerrisk">{{cite book |title=The Linux Programming Interface |last=Kerrisk |first=Michael |year=2010 |publisher=No Starch Press |page=921}}</ref>

SVR1 ran on [[Digital Equipment Corporation|DEC]] [[PDP-11]] and [[VAX]] [[minicomputer]]s.

=== SVR2 ===
[[File:VAX 11-780 intero.jpg|thumb|The [[Digital Equipment Corporation|DEC]] [[VAX-11/780]] was the porting base for SVR2.]]

AT&T's UNIX Support Group (USG) transformed into the UNIX System Development Laboratory (USDL), which released System V Release 2 in 1984. SVR2 added [[Unix shell|shell]] functions and the [[System V Interface Definition|SVID]]. SVR2.4 added [[demand paging]], [[copy-on-write]], [[shared memory]], and record and [[file locking]].

The concept of the "porting base" was formalized, and the DEC [[VAX-11/780]] was chosen for this release. The "porting base" is the so-called original version of a release, from which all porting efforts for other machines emanate.

Educational source licenses for SVR2 were offered by AT&T for US$800 for the first CPU, and $400 for each additional CPU. A commercial source license was offered for $43,000, with three months of support, and a $16,000 price per additional CPU.<ref>{{cite web |title=UNIX System V and add on applications prices |url=https://www.bell-labs.com/usr/dmr/www/licenses/pricelist84.pdf |publisher=AT&T International |date=24 February 1983 |access-date=24 January 2024}}</ref>

[[Apple Computer]]'s [[A/UX]] operating system was initially based on this release. [[Xenix|SCO XENIX]] also used SVR2 as its basis. The first release of [[HP-UX]] was also an SVR2 derivative.<ref name="Rosen"/>{{rp|33}}

Maurice J. Bach's book, ''The Design of the UNIX Operating System'', is the definitive description of the SVR2 kernel.<ref>{{Citation
|last=Bach
|first=Maurice
|title=The Design of the UNIX Operating System
|publisher=Prentice Hall
|year=1986
|bibcode=1986duos.book.....B
|isbn=0-13-201799-7
|url=https://archive.org/details/designofunixoper00bach
}}</ref>

=== SVR3 ===
[[Image:3B2_model_400_sitting_on_grass.jpg|thumb|The AT&T [[3B series computers#3B2|3B2]] line of [[minicomputer]]s was the porting base for SVR3.]]

AT&T's UNIX System Development Laboratory (USDL) was succeeded by AT&T Information Systems (ATTIS), which distributed UNIX System V, Release 3, in 1987.<ref>{{citation | author=Marshall Kirk McKusick | author-link=Marshall Kirk McKusick | chapter=History of the UNIX System | title=The Design and Implementation of the FreeBSD Operating System | edition=2nd | year=2015 | pages=23–28}}</ref> SVR3 included [[STREAMS]], [[Remote File Sharing]] (RFS), the File System Switch (FSS) [[virtual file system]] mechanism, a restricted form of [[shared library|shared libraries]], and the [[Transport Layer Interface]] (TLI) network [[application programming interface|API]]. The final version was Release 3.2 in 1988, which added binary compatibility to [[Xenix]] on Intel platforms (see [[Intel Binary Compatibility Standard]]).

User interface improvements included the "layers" windowing system for the [[Blit (computer terminal)|DMD 5620]] graphics terminal, and the SVR3.2 [[curses (programming library)|curses libraries]] that offered eight or more color pairs and other at this time important features (forms, panels, menus, etc.). The [[3B series computers#3B2|AT&T 3B2]] became the official "porting base."

[[SCO UNIX]] was based upon SVR3.2, as was [[Interactive Systems Corporation|ISC]] [[Interactive Unix|386/ix]]. Among the more obscure distributions of SVR3.2 for the 386 were ESIX 3.2 by [[Everex]] and "System V, Release 3.2" sold by Intel themselves; these two shipped "plain vanilla" AT&T's codebase.<ref name="IW1989">{{cite journal|author=Jeff Tye|title=Other OSs That Run Unix on a 386|url=https://books.google.com/books?id=ijAEAAAAMBAJ&pg=PT77|date=10 July 1989|journal=InfoWorld|pages=62|issn=0199-6649}}</ref>

[[IBM]]'s [[AIX operating system]] is an SVR3 derivative.

=== SVR4 === <!-- This section is linked from [[SVR4]] -->
[[File:HP-HP9000-C110-Workstation 10.jpg|thumb|[[HP 9000]] C110 running [[HP-UX]] in console mode]]
[[File:Openwindows.jpg|thumb|[[OpenWindows]], an early [[desktop environment]] for SVR4]]
[[File:HP-HP9000-735-99-Workstation 02.jpg|thumb|[[HP 9000]] 735 running [[HP-UX]] with the [[Common Desktop Environment]] (CDE)]]
[[File:Unix SVR4.2 mousepad.jpg|thumb|'Catch the wave' promotional mousepad for SVR4.2]]
[[File:Sun Ultra 20 Workstation (2005).jpeg|thumb|[[Sun Ultra series|Sun Ultra 20]] with [[Solaris (operating system)|Solaris]] 10]]

System V Release 4.0 was announced on October 18, 1988<ref>{{cite press release
 |title=  SEVERAL MAJOR COMPUTER AND SOFTWARE COMPANIES ANNOUNCE STRATEGIC COMMITMENT TO AT&T'S UNIX SYSTEM V, RELEASE 4.0
 |publisher= Amdahl, Control Data Corporation, et al.
 |date= October 18, 1988
 |url= http://groups.google.com/group/comp.unix.questions/msg/2e02a599c5c62848
 |access-date= 2007-01-01
  }}</ref> and was incorporated into a variety of commercial Unix products from early 1989 onwards.<ref name="levenez"/>  A joint project of AT&T Unix System Laboratories and [[Sun Microsystems]],<ref name="patton19880118">{{Cite magazine |last=Patton |first=Carole |date=18 January 1988 |title=Sun and AT&T Plan to Engineer Next-Generation Unix System 
 |url=https://books.google.com/books?id=Dz8EAAAAMBAJ&pg=PA11#v=onepage&q&f=false |access-date=2025-05-25 |magazine=[[InfoWorld]] |page=11 |volume=10 |issue=3}}</ref> it combined technology from:

* SVR3
* [[Berkeley Software Distribution|4.3BSD]]
* [[Xenix]]
* [[SunOS]]

New features included:

* From BSD:
** [[TCP/IP]] support
** Sockets
** [[Unix File System|UFS]]
** Support for multiple groups
** [[C shell]]
* From SunOS:
** [[Virtual file system]] interface (replacing File System Switch in System V Release 3)
** [[Network File System (protocol)|NFS]]
** New virtual memory system including support for [[mmap|memory mapped]] files
** Improved shared library system based on the SunOS 4.x model<ref name="Levine_1999_CH10"/>
** [[OpenWindows]] [[GUI]] environment
** [[External Data Representation]] (XDR) and [[ONC RPC]]
* From Xenix:
** x86 [[device driver]]s
** Binary compatibility with Xenix (in the x86 version of System V)
* [[KornShell]]
* [[C (programming language)#ANSI C and ISO C|ANSI X3J11 C]] compatibility
* Multi-National Language Support (MNLS)
* Better [[internationalization and localization|internationalization]] support
* An [[application binary interface]] (ABI) based on [[Executable and Linkable Format]] (ELF)
* Support for standards such as [[POSIX]] and [[X/Open]]

Many companies licensed SVR4 and bundled it with computer systems such as [[workstation]]s and [[network server]]s. SVR4 systems vendors included [[Atari Corporation|Atari]] ([[Atari System V]]), [[Commodore International|Commodore]] ([[Amiga Unix]]), [[Data General]] ([[DG/UX]]), [[Fujitsu]] ([[UXP/DS]]), [[Hitachi]] (HI-UX), Hewlett-Packard (HP-UX), [[NCR Corporation|NCR]] ([[Unix/NS]]), [[NEC]] ([[EWS-UX]], UP-UX, UX/4800, [[SUPER-UX]]), [[Oki Electric Industry|OKI]] (OKI System V), [[Pyramid Technology]] ([[DC/OSx]]), [[Silicon Graphics|SGI]] ([[IRIX]]), [[Siemens]] ([[SINIX]]), [[Sony]] ([[Sony NEWS|NEWS-OS]]), [[Sumitomo Electric Industries]] (SEIUX), and [[Sun Microsystems]] ([[Solaris (operating system)|Solaris]]) with [[illumos]] in the 2010s as the only [[open-source software|open-source]] platform.

Software porting houses also sold enhanced and supported [[x86 architecture|Intel x86]] versions. SVR4 software vendors included [[Dell]] (Dell UNIX),<ref>{{Citation
 |title=Technologists notes&nbsp;— A brief history of Dell UNIX
 |url=http://technologists.com/notes/2008/01/10/a-brief-history-of-dell-unix/
 |date=10 January 2008
 |access-date=2009-02-18
}}</ref> [[Everex]] (ESIX), Micro Station Technology (SVR4), [[Microport Systems|Microport]] (SVR4), and UHC (SVR4).<ref>[[Eric S. Raymond]], [http://www.catb.org/~esr/faqs/clone-unix-guide.txt A buyer's guide to UNIX versions for PC-clone hardware], posted to [[Usenet]] November 16, 1994.</ref>

The primary platforms for SVR4 were Intel x86 and [[SPARC]]; the SPARC version, called Solaris 2 (or, internally, [[SunOS]] 5.x), was developed by Sun. The relationship between Sun and AT&T was terminated after the release of SVR4, meaning that later versions of Solaris did not inherit features of later SVR4.x releases. Sun would in 2005 release most of the source code for Solaris 10 (SunOS 5.10) as the [[open-source software|open-source]] [[OpenSolaris]] project, creating, with its forks, the only open-source (albeit heavily modified) System V implementation available. After [[Oracle Corporation|Oracle]] took over Sun, Solaris was [[Fork (software development)|fork]]ed into proprietary release, but [[illumos]] as the continuation project is being developed in open-source.

A consortium of Intel-based resellers including [[Unisys]], [[International Computers Limited|ICL]], [[NCR Corporation]], and [[Olivetti]] developed SVR4.0MP with [[multiprocessing]] capability (allowing system calls to be processed from any processor, but interrupt servicing only from a "master" processor).<ref>
{{Citation
 |title=Unix Internatl. and USL release early version of SVR4 multiprocessing software
 |url=http://www.allbusiness.com/technology/computer-software/165194-1.html
 |date=17 June 1991
 |archive-url=https://web.archive.org/web/20100111232743/https://www.allbusiness.com/technology/computer-software/165194-1.html
 |archive-date=2010-01-11
 |access-date=2009-04-22
}}
</ref>

Release 4.1 ES (Enhanced Security) added security features required for [[Trusted Computer System Evaluation Criteria|Orange Book]] B2 compliance and [[Access Control List]]s and support for dynamic loading of kernel modules.<ref>{{cite journal |title=Unix International reviews the Unix System V.4 story so far |author=William Fellows |date=13 August 1992 |journal=Computer Business Review |url=http://www.cbronline.com/news/unix_international_reviews_the_unix_system_v4_story_so_far |access-date=2008-10-31 |archive-url=https://web.archive.org/web/20090221065610/http://www.cbronline.com/news/unix_international_reviews_the_unix_system_v4_story_so_far |archive-date=2009-02-21}}</ref><ref>
{{Citation
 |title=Computer Security
 |first=Matt
 |last=Bishop
 |publisher=Addison Wesley
 |date=December 2, 2002
 |isbn=0-201-44099-7
 |page=505
}}
</ref>

=== SVR4.2 / UnixWare ===
In 1992, AT&T USL engaged in a joint venture with [[Novell]], called [[Univel]]. That year saw the release System V.4.2 as Univel [[UnixWare]], featuring the [[Veritas File System]]. Other vendors included UHC and Consensys. Release 4.2MP, completed late 1993, added support for multiprocessing and it was released as UnixWare 2 in 1995.<ref>{{Citation
 |url=http://www.novell.com/news/press/archive/1995/03/pr00026.html
 |title=UnixWare 2 Product Announcement Questions& Answers
 |year=1995
}}</ref>

Eric S. Raymond warned prospective buyers about SVR4.2 versions, as they often did not include on-line [[man pages]]. In his 1994 buyers guide, he attributes this change in policy to Unix System Laboratories.<ref>{{cite web|url=http://www.catb.org/~esr/faqs/clone-unix-guide.txt|title=PC-clone UNIX Software Buyer's Guide|author=Eric S. Raymond|date=16 November 1994|access-date=6 May 2014}}</ref>

=== SVR5 / UnixWare 7 ===
The [[Santa Cruz Operation]] (SCO), owners of Xenix, eventually acquired the UnixWare trademark and the distribution rights to the System V Release 4.2 codebase from Novell, while other vendors (Sun, IBM, HP) continued to use and extend System V Release 4. Novell transferred ownership of the Unix trademark to [[The Open Group]]. 

System V Release 5 was developed in 1997 by the [[Santa Cruz Operation]] (SCO) as a merger of [[SCO OpenServer]] (an SVR3-derivative) and UnixWare, with a focus on large-scale servers.<ref name="Rosen">{{cite book |author=Kenneth H. Rosen |year=1999 |title=UNIX: The Complete Reference |publisher=McGraw-Hill Professional}}</ref>{{rp|23,32}} It was released as SCO UnixWare 7. SCO's successor, [[The SCO Group]], also based [[SCO OpenServer]] 6 on SVR5, but the codebase is not used by any other major developer or reseller.

=== SVR6 (cancelled) ===
System V Release 6 was announced by SCO to be released by the end of 2004, but was apparently cancelled.<ref>{{cite web|url=http://www.infoworld.com/t/platforms/sco-updates-unix-openserver-product-plans-798 |title=SCO updates Unix, OpenServer product plans |website=InfoWorld |date=August 19, 2003 |author=Deni Connor}}</ref> It was supposed to support 64-bit systems.<ref>[https://archive.today/20120722095807/http://website.scobenelux.com/roadmap.php SCO UNIX Roadmap at Archive.is]</ref> SCO also introduced Smallfoot in 2004, a low-resource "embeddable" variant of UnixWare for dedicated commercial and industrial applications, in an attempt that was perceived as a response to the growing popularity of Linux.<ref name="sdtimes20040615_smallfoot">{{ cite magazine | url=https://archive.org/details/sdtimes106/page/n24/mode/1up | title=SCO Steps Into Embedded Market With Smallfoot | magazine=Software Development Times | last1=Correia | first1=Edward J. | date=15 June 2004 | access-date=24 May 2024 | issue=106 | pages=25 }}</ref> The industry has since coalesced around [[The Open Group]]'s Single UNIX Specification version 3 ([[Single UNIX Specification|UNIX 03]]).