The original operating system was first introduced in 1984 as being integral to the original Macintosh, and referred to as the 'System'. for air Macintosh line of computer systems. Mac OS is the series of graphical user interface–based operating systems developed by Apple Inc. OS X: Closed source (with open-source components)Ĭlassic Mac OS: January 24, 1984 37 years ago ( )