Mac OS (Classic)

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 classic Mac OS shared many features with the Lisa OS, such as the trash can. Also, it relied entirely on its GUI, while most operating systems of that era relied on command prompts. When the Mac OS booted up, Finder was the default displayed application. It allowed users to launch single apps and browse files. Because the OS was single-tasking, users were required to quit apps before pulling up Finder or opening new apps.

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.


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…