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.

The Macintosh System Software borrowed from 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.x". This is not to be confused with "System Software 1", which was a software bundle that included System 3.1 and Finder 5.2.

Versions of System 1

 * System 0.85 (pre-release)
 * System 1.0
 * System 1.1