The Gamasutra web article on this is not as pretty. But, it includes the RSP microcode.
http://web.archive.org/web/20081221184231/http://www.gamasut... (edit, link fixed, thanks!)
If you like this kind of stuff, check out https://www.reddit.com/r/TheMakingOfGames/ and https://www.reddit.com/r/videogamescience/ I often post games-related stuff I find here to there. But, this might be the first time I’ve seen something posted to HN because it was first posted there :)