Macintosh System 7
- Released: May 13, 1991
- Final Release: 7.6.1, Apr 7, 1997
Macintosh System 7 was the first release to run on PowerPC processors (as of System 7.1.2) in addition to the Macintosh’s original 68k processors. As an evolution of the Macintosh’s original system software codebase, it lacked features that were important for the increasingly-advanced software used on personal computers: preemptive multitasking, multithreading, and protected memory.
The operating system was renamed to Mac OS as part of a short-lived program allowing third-party manufacturers to create officially-licensed “clone” hardware that would run the same software as Macintoshes.