Expansion Pak

The Expansion Pak is a RAM add-on for the Nintendo 64 game console, released in 1999. It doubles the total amount of RAMBUS RDRAM in the Nintendo 64 from 4 MB to 8 MB. By increasing system memory, there is potential for greater screen resolution, more detailed graphics, and higher frame rate. The Nintendo 64DD was the initial reason the Pak was made, because the extra RAM would be required to run the add-on. It replaces the Nintendo 64's Jumper Pak, which is simply a RAMBUS bus terminator.

The only games that require its use are The Legend of Zelda: Majora's Mask and Donkey Kong 64 (originally the Expansion Pak was included with purchase of the latter). The Expansion Pak was utilized in The Legend of Zelda: Majora's Mask for more onscreen characters at one time, as shown in Clock Town. Also, without the add-on, most of Perfect Dark is inaccessible (including the single player mode). The box for Perfect Dark included the disclaimer, "Expansion Pak Required for Maximum Gameplay!" It was also used in Starcraft 64, to unlock levels from the popular Brood War add-on for the PC version of the game.

Several third-party substitutes were released; however, complaints arose regarding stability and overheating issues, in addition to often being larger than normal size, causing them to stick out of the system.