Word was first released in the spring of 1983, and free demonstration copies of the application were bundled with the November 1983 issue of PC World, making it one of the first programs to be distributed on-disk with a magazine. (Earlier magazine on-disk distributions included Robert Uiterwyk's BASIC in the May 1977 issue of Information Age.) However, Xenix was never sold to end users directly although it was licensed to many software OEMs for resale. It grew to become the most popular version of Unix, measured by the number of machines running it (note that Unix is a multi-user operating system, allowing simultaneous access to a machine by several users). By the mid-1980s Microsoft had gotten out of the Unix business, except for its ownership stake in SCO.