| Version 7 Unix | |
|---|---|
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| Developer | AT&T Bell Laboratories |
| Written in | C,assembly |
| OS family | Unix |
| Working state | Historic |
| Source model | Originallyproprietary software, nowopen source |
| Initial release | 1979; 47 years ago (1979) |
| Marketing target | Minicomputers |
| Available in | English |
| Supported platforms | DECPDP-11,VAX (32v),x86 |
| Kernel type | Monolithic |
| Default user interface | Command-line interface (Bourne shell) |
| License | Originallyproprietarycommercial software, nowfree software under aBSD-like license |
| Preceded by | Version 6 Unix |
| Succeeded by | Version 8 Unix |
Version 7 Unix, also calledSeventh Edition Unix,Version 7 or justV7, was an important early release of theUnixoperating system. V7, released in 1979, was the lastBell Laboratories release to see widespread distribution before the commercialization of Unix byAT&T Corporation in the early 1980s. V7 was originally developed forDigital Equipment Corporation'sPDP-11 minicomputers and was later ported to other platforms.
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 bySixth Edition, which was the first version licensed to commercial users.[1] Development of theResearch Unix line continued with theEighth Edition, which incorporated development from4.1BSD, through the Tenth Edition, after which the Bell Labs researchers concentrated on developingPlan 9.
V7 was the first readilyportable version of Unix. As this was the era ofminicomputers, 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 firstSun workstations (then based on theMotorola 68000) ran a V7 port byUniSoft;[2] the first version ofMicrosoftXenix for theIntel 8086 was derived from V7, andOnyx Systems soon produced aZilogZ8000 computer running V7. TheVAX port of V7, calledUNIX/32V, was the direct ancestor ofUNIX System V[disputed –discuss] and the popular4BSD family of Unix systems.
The group at theUniversity of Wollongong that hadported V6 to theInterdata 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]
DEC distributed their own PDP-11 version of V7, calledV7M (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.[3] UEG evolved into the group that later developedUltrix.
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.[4]
The number ofsystem calls in Version 7 was only around 50, while later Unix and Unix-like systems continued to add many more:[5]
Version 7 of the Research UNIX System provided about 50 system calls,4.4BSD provided about 110, andSVR4 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. As of December 2025Linux 6.18 has 470, andFreeBSD 15 has 598.
In 2002,Caldera International released[6] V7 asFOSS under apermissiveBSD-likesoftware license.[7][8][9]
Bootable images for V7 can still bedownloaded today, and can be run on modern hosts using PDP-11 emulators such asSIMH.
Anx86 port has been developed by Nordier & Associates.[10]
Paul Allen maintained[when?] several publicly accessible historic computer systems, including a PDP-11/70 running Unix Version 7.
Many new features were introduced in Version 7.
A feature that did not survive long was a second way (besides pipes) to dointer-process communication: multiplexed files. A process could create a special type of file with thempx system call; other processes could then open this file to get a "channel", denoted by afile descriptor, which could be used to communicate with the process that created the multiplexed file.[13] Mpx files were considered experimental, not enabled in the default kernel,[14] and disappeared from later versions, which offeredsockets (BSD) orCB UNIX's IPC facilities (System V) instead[15] (although mpx files were still present in 4.1BSD[16]).
Sun-1's were the very first models ever produced by Sun. The earliest ran Unisoft V7 UNIX; SunOS 1.x was introduced later.
mpx(2) – Version 7 Unix Programmer'sManualmkconf(1) – Version 7 Unix Programmer'sManual| Research |
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