Towards the bottom of that page it mentions color forth. That is what he uses. It is a forth like language that removed punctuation and replaces it with colors.
Ah, upon further reading, colorForth has its own operating system, so he probably uses that too. I had seen the forth bits, but the GP implied he was using some non-Unix OS, and I was still curious about that.
Forth is conventionally a compiler, REPL, editor and OS all in one package. If I recall correctly, the reference implementation of ColorForth happens to run as a Windows application, but it pretty much lives in its own memory image and could probably be made bootable.
Sorry I wasn't clearer about that. Much like there were Lisp machines in the 80s Mr. Moore ran(perhaps still runs) a company that does custom Forth machines. So he uses his own hardware and his own software, turtles all the way down so to speak.
