Prolog Interpreter
Written by John MacLean
Released into the Public Domain

General Notes about John MacLean's source code
John sold his hard disk complete with contents when he decided to move on from Apple II development. He has agreed to place his source code into the public domain for the benefit of other programmers. 
If you use John's source code, please credit him in your program and documentation.
John used Roger Wagner Publishing's Merlin Assembler. 

Notes about this release
The front end shell works well, as does the editor. However, the interpreter does
not interpret anything. If you manage to get the interpreter prompt, you'll have to use ctrl-reset to break out again. 
Provision was made to automatically load library and user files at load time: "LIBRARY" and "STARTUP".
The main link files are named ASM.S (to assemble segments), EC.S (link IIe & IIc segments), GS.S (link IIgs segments), and PROLOG.SYSTEM.S (create system file).
You'll need to link the ASM file twice, once for the EC version, and again for the GS version. Answer "Y" to the questions on the first run, and "N" on the second.