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Chapter 1 - Introduction to SVR4

UNIX Systems Programming for SVR4
David A. Curry
 Copyright © 1996 O'Reilly & Associates, Inc.

Chapter 1: Introduction to SVR4
Overview
Between 1969 and 1970, Ken Thompson, Dennis Ritchie, and other members of the Computer Research Group at Bell Laboratories designed and built the original UNIX operating system on the now-famous “little-used PDP-7 sitting in the corner.” In 1970, UNIX was ported from the PDP-7 to a PDP-11/20, along with a text editor and a program called roff, a predecessor to troff. This UNIX system, running with no memory protection and 500 Kbytes of disk space, supported three concurrent users editing and formatting, and also the original group of people doing further UNIX development. The documentation for this system, dated November 1971, was labeled “First Edition.”
Between 1971 and 1979, a number of UNIX variants were created inside Bell Laboratories. The main version, developed by Thompson and his coworkers, evolved through Version 4 (the first version written in C), Version 6 (the first version to be licensed outside Bell Labs), and finally Version 7. Most people would not recognize any of these versions, except perhaps Version 7, as looking much like the UNIX of today. During this same time, a number of other lesser-known versions were developed by various groups inside Bell Labs, including PWB/UNIX, MERT, RT, and CB UNIX. UNIX by this time had been ported to several varieties of PDP-11, the Interdata 8/32, the IBM VM/370 environment, and even the IBM Series 1. Shortly after its release, Version 7 was ported to the VAX and called UNIX 32V.
Outside the Labs, UNIX development took place at several universities. The most notable was the University of California at Berkeley. The first Berkeley Software Distribution (BSD), based on UNIX Version 6 for the PDP-11, was released in 1977. Other notable releases from Berkeley included 4.0BSD for the VAX in 1980, 4.1BSD in 1981, 4.2BSD in 1983, and 4.3BSD in 1984. Development continued on the PDP-11 as well, with 2.8BSD in 1982, 2.9BSD in 1983, and 2.10BSD in 1987. These releases essentially ported most of the new software from the 4.x BSD releases to the aging PDP-11. In 1993, the Computer Science Research Group at Berkeley made its last release of UNIX, 4.4BSD, and disbanded.
Meanwhile, back at Bell Laboratories, the UNIX System Development Laboratory had been created. Between 1977 and 1982, this group took several internal variants of UNIX, predominantly PWB/UNIX, CB UNIX, and UNIX 32V, and merged them into a single commercial system known as System III. This was the last version of UNIX licensed by AT&T through Western Electric before divestiture (caused by an antitrust suit brought by the U.S. government) broke AT&T into several pieces. As part of divestiture, UNIX was given to AT&T Information Systems, which in early 1983 announced UNIX System V. System V Release 2 (SVR2) was released in 1984, and System V Release 3 (SVR3) in 1986. Both of these releases became very popular.
In the late 1980s, AT&T and Sun Microsystems entered into a cooperative venture to develop a new version of UNIX. This version would merge the “best of the best” features from AT&T's SVR3, Berkeley's 4.3BSD, Sun's SunOS, and Microsoft's XENIX. In November 1989, UNIX System V Release 4 (SVR4), the result of this venture, was released. However, it would take two more years for a major computer vendor to release an SVR4-based operating system. Sun released Solaris 2.0 in 1991, followed by Silicon Graphics' IRIX 5.0 in 1994, and Hewlett-Packard's HP-UX 10.0 in 1995.

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