Released: October 1999 (9.0) December 2000 (9.0.4)
System Requirements: PowerPC processor, 32 MB of physical RAM, with virtual memory set to at least 40 MB, and 190 to 250 MB of hard disk space
Distribution Media: CD-ROM
Apple Order Number: n/a
Versions: 9.0, 9.0.1, 9.0.2, 9.0.3, 9.0.4
History: Mac OS 9 was the last version of the classic Mac OS, the operating system of the Apple Macintosh computer, which was widely used in the late 1990s, as the successor to Mac OS 8, up until the debut of Mac OS X in 2001. It featured Sherlock 2, an updated searching utility and also supported multiple users without additions such as At Ease or third-party products. Codenamed Sonata, It was originally intended to debut as Mac OS 8.7. Mac OS 9 was released on October 23, 1999 and only supported PowerPC based Macs. Apple billed Mac OS 9 as "The best Internet operating system ever". Apple updated Mac OS 9 with a series of bugfixes and minor enhancements, most notably versions 9.0.4 and 9.1 (which provided CD burning support within the Finder), in 2000 and 2001.
History Source: Wikipedia
History Source Address: http://en.wikipedia.org/wiki/Mac_OS_9