[quote name='WhipSmartBanky']I don't know if this is related, but some early North American carts had standard Phillips head screws instead of security screws. Some of these games had a Famicom ROM board with a pin adapter hooked to it. You could pop the game open and basically get a free Famicom->NES cartridge converter. I don't recall Mega Man being one of these though - I thought it was more along the lines of Gyromite and Hogan's Alley.[/QUOTE]
yea, these were nintendo-produced/developed games, not 3rd party titles. the reason for this was that they ran out of nes cart boards one christmas and had to come up with a solution... which involved a famicom-nes adapter fit inside the cartridge.
as for the number/type of screws on the back of a megaman cart... no idea. did capcom do a re-issue of the game after it became a popular series?