On January 24, 1984, Apple Computer Inc. (now Apple Inc.) introduced the Macintosh personal computer, retroactively renamed to the Macintosh 128K model. The operating system of early Macintoshes is named "System Software" or "System", and its ensuing series was later renamed to Mac OS after 7.5.[1] The Macintosh platform is credited with having popularized the concept of the graphical user interface.[2]