Mac OS (Classic)
Definition - What does Mac OS (Classic) mean?
The classic Mac OS is Apple's operating system (OS) used in Macintosh (Mac) computers prior to the release of the Mac OS X. Mac OS X is Apple's current OS series.
In 1984, Apple released the original Mac OS. Known as Mac System Software, it came on a single floppy disk and included a graphical user interface (GUI) that focused on single users and tasks. Thus, multitasking was not required or used until subsequent Mac OS versions were released.
In fall 1999, the most recent classic Apple OS was released as Mac OS 9. A major release, Mac OS 9 was packed with new software tools and features and paved the way for Mac OS X.
Techopedia explains Mac OS (Classic)
The file system of the classic Mac OS was known as the Macintosh File System (MFS). It was flat, meaning that all files were stored in a single directory. However, system software displayed folders in a nested format. Also, each disk contained an empty folder in the root storage level. Renaming this folder was required before creating new folders, and the OS copied the empty folder each time it was renamed.