High Quality Content by WIKIPEDIA articles! On January 24, 1984, Apple Computer Inc. (now Apple Inc.) introduced the Macintosh personal computer, with the Macintosh 128K model, which came bundled with what was later renamed the Mac OS, but then known simply as the System Software. The Macintosh is generally credited with popularizing the graphical user interface. The Mac OS has been pre-installed on almost every Macintosh computer sold. The operating system was also sold separately in retail stores. The original Macintosh system software was partially based on the Lisa OS, previously released by Apple for the Lisa computer in 1983 and, as part of an agreement allowing Xerox to buy shares in Apple at a favorable rate, it also used concepts from the Xerox PARC Xerox Alto, which Steve Jobs and several other Macintosh team members had previewed.