Controller PAK

The Controller Pak is the console's memory card, comparable to those seen in the PlayStation and other CD-ROM-based video game consoles. Certain games allow saving of game files to the Controller Pak, which plugs into the back of the Nintendo 64 controller (as do the Rumble and Transfer Paks). The Controller Pak was marketed as a way to exchange data with other Nintendo 64 owners, since information saved on the game cartridge can not be transferred between cartridges.