MacOS version history (Classic Mac)
The "Classic" Mac OS[4][5] is a graphical user interface-based operating system developed by Apple Inc. for its Macintosh line of personal computers from 1984 until 2001, the original member of the family of Macintosh operating systems. The Macintosh platform, which was introduced in the classic Mac OS, is credited with having popularized the early GUI concept.[6] Mac OS was preinstalled on every Macintosh computer that was made during the era it was developed; it was also sold separately in retail stores. Apple released the original Macintosh on January 24, 1984. Its early system software was partially based on the Lisa OS, previously released by Apple for the Lisa computer in 1983; as part of an agreement allowing Xerox to buy shares in Apple at a favorable price, it also used concepts from the Xerox PARC Alto computer, which former Apple CEO Steve Jobs and other Macintosh team members had previewed.[1] The operating system integral to the Macintosh was originally named