The Expansion Pak is a RAM add-on for the Nintendo 64 game console, which was released in 1998. It gives the Nintendo 64 an extra 4MB of RDRAM, for a total of twice the original (4MB) of on-board RAM. This allows for greater screen resolution, more detailed graphics, and a higher frame rate. The Nintendo 64DD was the initial reason the Expansion Pak was made, because the extra RAM would be required to run the add-on.

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 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. It was also used in Starcraft 64 to unlock levels from the popular Brood War add-on for the PC-version of the game.

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