Proprietary : Mac Os

Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The original version was the integral and unnamed system software first introduced in 1984 with the original Macintosh, and referred to simply as the "System" software. The System was renamed to Mac OS in 1996 with version 7.6. The System is credited with popularizing the graphical user interface concept.