Has anybody ever attempted to figure out the differences between the different CPU and PPU revisions, aside from the obvious ones like RGB output or PAL compatibility? I have three or four different revisions in my NES collection, the oldest being E (in my early NES) and the newest (in my AV Fami) being either G or H. The only difference I've noticed is the color of the screen at reset; it's usually either purple or brown on the 2A03E/2C02E, and always grey on the later ones. Also, when using a PowerPak, certain games either don't run or behave differently depending on the revision, but that might be due to other factors (variances in manufacturing, perhaps).