System 6

System 6 (or System Software 6) is the sixth major release of the classic Mac OS operating system for Macintosh computers, made by Apple Computer. It was released in 1988. It is a monolithic operating system, with cooperative multitasking based on an improved MultiFinder. The boxed version cost US$49 (equivalent to about $130 in 2023), and it was included with all new Macintosh computers until 1991, when it was succeeded by System 7.