System 1

System 1 (Macintosh System Software) is the very first version of the Macintosh system software, released with the original Macintosh 128K and Macintosh 512K computers. This software borrowed the user interface developed for the Apple Lisa computer line, based on user interface rules learned from the Xerox PARC team. System 1 is also a generalised term for "any version of System 1", or "System 1.x". This is not to be confused with "System Software 1" which was a software bundle including System 3.1 and Finder 5.2.

Versions of System 1

 * System 0.85
 * System 1.0
 * System 1.1