[tbrock]

To me it seems as if the PPU is the most poorly explained (or difficult to understand) component of the NES. Most documentation heavily glosses over details and specifics or doesn't provide any reasoning as to why such a system was designed. This is a great guide.

If you have some spare time and want to tinker a bit, writing your own NES emulator is a great way to learn something new (or learn a new language if you've done it before)

[loganfsmyth]

Definitely second writing your own as a way to learn. I wrote one that could mostly play pong a while back and it was super satisfying. The PPU was definitely the toughest part.