Mac OS
Mac OS, formerly System Software, is the series of operating systems developed for the Macintosh family of personal computers by Apple from 1984 to 2001, starting with System 1 and ending with Mac OS 9. It was first introduced together with the original Macintosh in January 24, 1984. The original Macintosh System 1 is partially based on the Apple Lisa's OS. In 1997, Apple rebranded the Macintosh System Software to Mac OS, which continue to be developed until the introduction of Mac OS X.
The classic Mac OS was originally written for the Motorola 68k architecture from 1984 to 1994, after which Apple transitioned to PowerPC. PowerPC would be used until the classic Mac OS's discontinuation in 2002. Classic Mac OS was based on a simple kernel design, which eventually became too limited and crash-prone for applications. In response, Apple bought NeXT and used NeXTSTEP as a base to develop Mac OS X.
