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UNIX System III
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<p>UNIX System III (or System 3) is a discontinued version of the <a href="/facts/Unix/0pNL2seI">Unix</a> operating system released by <a href="/facts/AT%2526T_Corporation/BfsX7eX2">AT&T</a>'s Unix Support Group (USG). </p><p>AT&T announced System III in late 1981, and it was first released outside of <a href="/facts/Bell_Labs/fKP5Gk0H">Bell Labs</a> in 1982. UNIX System III was a mix of various AT&T Unix systems: <a href="/facts/Version_7_Unix/ju5nRs7k">Version 7 Unix</a>, <a href="/facts/PWB%2fUNIX/jXR0LT4j">PWB/UNIX</a> 2.0, <a href="/facts/CB_UNIX/XpUouQIp">CB UNIX</a> 3.0, <a href="/facts/Multi-Environment_Real-Time/Gc0eJXYc">UNIX/RT</a> and <a href="/facts/UNIX%2f32V/hKyF5cqS">UNIX/32V</a>. System III supported the <a href="/facts/Digital_Equipment_Corporation/ztxs6keA">DEC</a> <a href="/facts/PDP-11/9HkGUzFn">PDP-11</a> and <a href="/facts/VAX/N3r13IHH">VAX</a> computers. </p><p>The system was apparently called System III because it was considered the outside release of UNIX/TS 3.0.1 and CB UNIX 3 which were internally supported Bell Labs Unices; its manual refers to it as UNIX Release 3.0 and there were no Unix versions called System I or System II. There was no official release of UNIX/TS 4.0 (which would have been <i>System IV</i>) either, so System III was succeeded by <a href="/facts/UNIX_System_V/Epm6GEY4">System V</a>, based on UNIX/TS 5.0. </p><p>System III introduced new features such as <a href="/facts/Named_pipe/g78xY9lC">named pipes</a>, the <a href="/facts/Uname/fx63hv3C">uname</a> system call and command, and the <a href="/facts/Run_queue/KwEQSl6o">run queue</a>. It also combined various improvements to <a href="/facts/Version_7_Unix/ju5nRs7k">Version 7 Unix</a> by outside organizations. However, it did not include notable additions made in <a href="/facts/Berkeley_Software_Distribution/XQKcURrh">BSD</a> such as the <a href="/facts/C_shell/8XRuIg0K">C shell</a> (csh) and screen editing. </p><p>Third-party variants of System III include (early versions of) <a href="/facts/HP-UX/hIvLDdJF">HP-UX</a>, <a href="/facts/IRIX/vK9rSatM">IRIX</a>, <a href="/facts/Interactive_Systems_Corporation/uWkY8Xv7">IS/3</a> and <a href="/facts/PC%2fIX/uWkY8Xv7">PC/IX</a>, <a href="/facts/PC-UX/GrqIkxgV">PC-UX</a>, <a href="/facts/PERQ/V68LfsKQ">PNX</a>, <a href="/facts/SINIX/VbdESF6k">SINIX</a>, <a href="/facts/Venix/tp21TLQu">Venix</a> and <a href="/facts/Xenix/G8sH08Tp">Xenix</a>. </p>