I wrote that code originally, back at MCC. There was an Interlisp-D code base (Doug had been at PARC — we even overlapped) but the hardware you could buy was j

I wrote that code originally, back at MCC. There was an Interlisp-D code base (Doug had been at PARC — we even overlapped) but the hardware you could buy was just way too slow. Plus the Symbolics machines were just better. So I started from scratch and had the core system running in a long week end. Instead of “just growing” it had a layered architecture that people could build upon. It was possible to integrate the new types so deeply into the system that they were indistinguishable from “system” types, which kept people from making mistakes or trying to be cute. Hacking lispms may have been the most productive development environment I’ve used in my nature life. Note: I had two fully decked out machines (8 MW of RAM — 40 whole MB), one with a color display. Probably $100K of hardware for one developer. They got their money’s worth, but honestly how many institutions could afford that?