Nice!

If you're interested in this kind of thing - this site: http://www.computerarcheology.com has a detailed disassembly of arcade Space Invaders(http://www.computerarcheology.com/Arcade/SpaceInvaders/). The site also contains partial disassembly of many other games e.g. Asteroids, Defender, Frogger, Galaga & Robotron.

"Pacman Dossier" had a great disassembly of Pac Man arcade, however rumour has it that Namco took it down.

Additionally, a little bit of Google-fu will also find you the commented disassembly of Donkey Kong arcade.

I can't help to be fascinated by the innovation shown in some of these early games.