Will add this here in case anyone comes across this thread: https://pcengines.ch/tp3.htm

It discusses TP 3.0's operation, supposedly based on a disassembly. It's less interesting than it sounds (it's mostly a high level overview of how a small compiler works, rather than a real study of TP internals), but it helps.

Long TP discussion thread with dead link here: https://news.ycombinator.com/item?id=10202299