The abbreviation Mac OS designates the original desktop operating system from Apple for the Macintosh. It was developed from 1982 and since version 7.6 it bears the final name Mac OS. The latest version of Mac OS 9 was the preinstalled standard operating system on a Mac until 2002. In addition, it was basically one of the first commercially distributed systems, with graphical user interface and mouse support.
Today, Mac OS X is often synonymous with the successor Mac OS X. However, when it comes to the classic version, often Mac OS Classic or Classic Mac OS is used as a name. With us you get systems from Apple, which use either one or the other variant, where we always specify the exact version number as possible in the product description.
Recent Mac OS systems included the Power Mac G4. However, this was followed immediately by the transition to Mac OS X. Once the Macs used an Intel hardware base, there was no more classic environment, which the official and virtualized Mac OS fell away. Apple only distributes current devices with the Mac OS X operating system.