An upgrade of the Mac operating system introduced in 1991. System 7 included virtual memory, increased memory addressing, hot links (Publish and Subscribe), multitasking (MultiFinder no longer optional), TrueType fonts and a variety of user interface enhancements.
System 7 Pro added PowerTalk communications, the AppleScript language and QuickTime for sound, movies and animation. System 7.5 advanced the online help with AppleGuide and more sophisticated graphics with QuickDraw GX. See macOS
(System/7) A sensor-based minicomputer from IBM introduced in 1970 and used for process control. It was superseded by the Series/1.