In 1969, Ritchie and Ken Thompson co-developed an interactive time-sharing operating system. They called it UNIX. Unix
demonstrated that a relatively small OS could be portable, machine independent, and affordable. The advent of the Unix workstation and the growth of networking have cinched Unix's place in computing. Since the late 1970s, Unix has had a profound impact on DOS, the Mac OS, Windows NT, and many others. In 1972 at ATT Bell Labs Ritchie developed the C programming language. C is now the dominant language in systems and microcomputer applications programming. Ritchie still works at ATT research labs, where he is developing OSes, including Plan 9 from Bell Labs.