The "classic" Mac OS is the original Macintosh operating system that was introduced in 1984 alongside the first Macintosh and remained in primary use on Macs until the introduction of Mac OS X in 2001.. Apple released the original Macintosh on January 24, 1984; its early system software was partially based on the Lisa OS and the Xerox PARC Alto computer, which former …

Computer operating systems (OSes) provide a set of functions needed and used by most application programs on a computer, and the links needed to control and synchronize computer hardware. On the first computers, with no operating system, every program needed the full hardware specification to run correctly and perform standard tasks, and its own drivers for …