Simplify the following text for a Grade 6 native English-speaking person.
Original: The original form of what Apple would later name the `` Mac OS '' was the integral and unnamed system software first introduced in 1984 with the original Macintosh , usually referred to simply as the System software .
Simplified: Mac OS was first made by Apple Inc. in 1984 . In those days Mac OS was called Macintosh System Software â `` which was shortened to System or SSW ( System Software ) .