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.
Macintosh 512Ke The Macintosh 512K enhanced (512Ke) was introduced in April 1986 as a cheaper alternative to the top-of-the-line Macintosh Plus, which had debuted three months previously. It was the same as the Macintosh 512K but with the 800K disk drive and 128K of ROM used in the Macintosh Plus. Like its predecessors, there was little room for expansion. Some companies did create memory upgrades that served to bring the machine up to 2 MB or more. It was the earliest Macintosh model able to run System Software 6. It was also the earliest that could be used as an AppleShare server and, with a bridge Mac, communicate with modern devices.