Whats the MMC1 chip?
The MMC1 chip is basically what made games like Zelda and Metroid possible without the FDS. That’s about as far as one needs to go. To allow a save game feature, one of the geniuses at Nintendo decided to put a battery in the cart itself to store the data. With those two things, the Legend of Zelda was easily ported to the NES. (As an aside, Metroid, another early FDS game, also came to the US, but used a very hairy password system.
