“Infocom’s ingenious code-porting tools for ‘Zork’ and other games have been found”
https://arstechnica.com/gaming/2023/11/infocoms-ingenious-code-porting-tools-for-zork-and-other-games-have-been-found/
Manual by Infocom: "Learning ZIL: everything you always wanted to know about writing interactive fiction but couldn’t find anyone still working here to ask"