ARCHIVED: What is Mac OS?

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Mac OS is the original primary operating system of Apple Computer's line of personal computers. The first version was released with the original "Thin" Macintosh (i.e., the Macintosh 128K) in 1984, and until the release of Mac OS X, Mac OS remained Apple's flagship operating system. Mac OS is characterized by a user-friendly graphical user interface (GUI), single-button mousing, and nearly universal plug-and-play support. In the spring of 2001, Apple transitioned from its original code base to Mac OS X, a very different operating system based on Unix and the Mach microkernel. Like its predecessor, Mac OS X maintains the traditional Mac OS ease of use, but with substantially improved stability.

For technical information, visit the Mac OS and Mac OS X Developer Connection pages at:

Note: Apple is no longer providing new releases or updates for Mac OS 9 and earlier. The latest release is Mac OS 9.2.2, which is designed primarily for use in the Classic environment of Mac OS X. The latest stand-alone release is Mac OS 9.1.

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Last modified on 2018-01-18 12:05:59.