<P> Bell Labs produced several versions of Unix that are collectively referred to as "Research Unix". In 1975, the first source license for UNIX was sold to Donald B. Gillies at the University of Illinois Department of Computer Science . UIUC graduate student Greg Chesson, who had worked on the UNIX kernel at Bell Labs, was instrumental in negotiating the terms of the license . </P> <P> During the late 1970s and early 1980s, the influence of Unix in academic circles led to large - scale adoption of Unix (BSD and System V) by commercial startups, including Sequent, HP - UX, Solaris, AIX, and Xenix . In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4 (SVR4), which was subsequently adopted by many commercial Unix vendors . </P> <P> In the 1990s, Unix and Unix - like systems grew in popularity as BSD and Linux distributions were developed through collaboration by a worldwide network of programmers . In 2000, Apple released Darwin, also a Unix system, which became the core of the Mac OS X operating system, which was later renamed macOS . </P> <P> Unix operating systems are widely used in modern servers, workstations, and mobile devices . </P>

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