MacWorks Plus was a complete implementation (port) of the Macintosh Plus 128K ROM on the Apple Lisa and Macintosh XL computer systems,  a contract developer named Chuck Lukaszewski, who was responsible for versions up through 1.1(h), which supported up to which graphical user interface-based operating system for Macintosh computers, and was shipped with various Macintosh computers until it was succeeded by System 7 in 1991?
System 6 System 6 (also referred to as System Software 6) is a graphical user interface-based operating system for Macintosh computers. It was released in 1988 by Apple Computer and was part of the classic Mac OS line of operating systems. System 6 was shipped with various Macintosh computers until it was succeeded by System 7 in 1991. The boxed version of System 6 cost $49 when introduced. System 6 is classed as a monolithic operating system. It featured an improved MultiFinder, which allowed for co-operative multitasking.
Jean-Marie Hullot Jean-Marie Hullot (born February 16, 1954) is a French computer scientist and programmer who authored important programs for the original Macintosh, NeXTSTEP and Mac OS X platforms. These include the SOS Interface for the Mac, which later became Interface Builder for NeXTSTEP (1985), and later still evolved into an important part of Mac OS X. He also led the iCal and iSync development teams for Mac OS X (2002).