Question: 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?
Context: An analog board is a circuit board that contains the majority of analog circuitry in certain Apple Macintosh computers.  The analog board was one of two circuit boards within many early Macintosh computers, including the Macintosh 128K/512K/Plus, Macintosh SE series, and Macintosh Classic series.  The analog board contained several capacitors, a battery compartment, and some other analog circuitry.  Some later all-in-one Macintosh computers also included analog boards, with the most recent being the iMac G3 and eMac.  In these computers, the analog board functioned as the power supply to other parts within the system, and also functioned to control the CRT display within the computer.  The other board was the logic board, which contained all of the computer's digital logic circuitry, such as the processor and memory. MacWorks XL was an Apple Lisa computer program which shipped with the Macintosh XL.  It allowed 64K Apple Macintosh ROM emulation so the Macintosh XL could run classic Mac OS programs. A Macintosh User Group (MUG) is a users' group of people who use Macintosh computers made by Apple Inc. or other manufacturers and who use the Apple Macintosh operating system (OS).  These groups are primarily locally situated and meet regularly to discuss Macintosh computers, the Mac OS, software and peripherals that work with these computers.  Some groups focus on the older versions of Mac OS, up to Mac OS 9, but the majority now focus on the current version of Mac OS, Mac OS X.  This user group began with the formation of the Apple User Group Connection. 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. MacWorks Plus was a complete implementation (port) of the Macintosh Plus 128K ROM on the Apple Lisa and Macintosh XL computer systems, and introduced in August 1988.  It was developed for Sun Remarketing of Cache Valley, Utah, under license from Apple Inc., by a contract developer named Chuck Lukaszewski, who was responsible for versions up through 1.1(h), which supported up to Macintosh System 6.0.3.  Dafax Processing Corp. with the assistance of Query Engineering, Inc. then further developed the environment to MacWorks Plus II, which continued Macintosh system support up to System 6.0.8 with the "Basic" version, and introduced a "Pro" version to extend support to the maximum possible for any 68000 processor: System 7.5.5.  Prior to MacWorks Plus, the maximum system supported by its predecessor MacWorks XL was System 3.2. BootX is a software-based bootloader designed and developed by Apple Inc. for use on the company's Macintosh computer range.  BootX is used to prepare the computer for use by loading all required device drivers and then starting-up Mac OS X by booting the kernel on all PowerPC Macintoshes running the Mac OS X 10.2 operating system or later versions.  Using BootROM, a read-only memory (ROM) computer chip containing OpenFirmware, a graphical bootsplash is shown briefly on all compatible Macintosh computers as a grey Apple logo with a spinning cursor that appears during the startup sequence.  The program is freely available as part of the Darwin operating system under the open source Apple Public Source License.  BootX was superseded by another nearly identical bootloader named codice_1 and an Extensible Firmware Interface ROM on the release of the Intel-based Mac. The "Classic" Mac OS is a graphical user interface-based operating system developed by Apple Inc. for its Macintosh family of personal computers from 1984 until 2001, the original member of the series of Macintosh operating systems.  The Macintosh platform, which was introduced in the classic Mac OS, is credited with having popularized the early GUI concept.  Mac OS was preinstalled on every Macintosh computer that was made during the era it was developed; it was also sold separately in retail stores. System 7 (codenamed "Big Bang" and sometimes retrospectively called Mac OS 7) is a single-user graphical user interface-based operating system for Macintosh computers and was part of the classic Mac OS line of operating systems.  It was introduced on May 13, 1991, by Apple Computer.  It succeeded System 6, and was the main Macintosh operating system until it was succeeded by Mac OS 8 in 1997.  Features added with the System 7 release included virtual memory, personal file sharing, QuickTime, QuickDraw 3D, and an improved user interface. The Macintosh XL is a modified version of the Apple Lisa personal computer made by Apple Computer, Inc. In the Macintosh XL configuration, the computer shipped with MacWorks XL, a Lisa program that allowed 64 K Macintosh ROM emulation.  An identical machine was previously sold as the Lisa 2/10 with the Lisa OS only. The family of Macintosh operating systems developed by Apple Inc. includes the graphical user interface-based operating systems it has designed for use with its Macintosh series of personal computers since 1984, as well as the related system software it once created for compatible third-party systems.
Answer: System 6