The Macintosh Operating System ( Mac OS ) is a program that allows a Macintosh computer to operate and be used by humans . Mac OS was first made by Apple Inc. in 1984 . Because drivers ( for printers , scanners , tablets , etc. ) written for the older Mac OS are not compatible with Mac OS X , and due to the lack of Mac OS X support for older Apple machines , a significant number of Macintosh users have still continued using the older classic Mac OS .