AT&T

   The parent company of Bell Laboratories, the original developers of Unix. For many years Bell Labs was one of the two major development centers for Unix (the other being the Computer Systems Research Group at the University of California at Berkeley), but in 1990, AT&T formed Unix Systems Laboratories, or USL, to continue the development of Unix. In 1993, USL was sold to Novell, and in 1995, Novell sold the rights to SCO (Santa Cruz Operation).

   See also Baby Bells; Regional Bell Operating Companies.