The Expansion Pak[c] (NUS-007) consists of 4 MB (megabytes) of random access memory (RAM)—which is RDRAM, the same type of memory used inside the console itself[10]—increasing the Nintendo 64 console's RAM from 4 MB to 8 MB of contiguous main memory.[10] It is installed in a port on top of the console and replaces the pre-installed Jumper Pak, which is simply a Rambus terminator.[9][10] Originally designed to accompany the 64DD disk drive expansion peripheral for its larger multimedia workstation applications, the Expansion Pak was launched separately in Q4 1998 and then bundled with the 64DD's delayed December 1999 Japan launch package.[citation needed] The Expansion Pak was bundled with Donkey Kong 64,[12][13] and in Japan, the Expansion Pak additionally came bundled with Zelda: Majora's Mask and Perfect Dark, though the games have been also available separately in other regions.[citation needed]
It was bundled with an "ejector tool" (NUS-012) meant for removing the original Jumper Pak.[citation needed]
Game developers took advantage of the increased memory in various ways, including greater visual appeal. The Expansion Pak is required in order to run two cartridge games, Donkey Kong 64 and The Legend of Zelda: Majora's Mask;[13][14] a third game, Perfect Dark, would lack most of its content (such as the single-player campaign) when no Expansion Pak was present, a fact described on the back cover as "approximately 35%" of the game being available in that case, arguably amounting to a mere demo mode.[15] It is also required for all 64DD software. In StarCraft 64, it is needed to unlock levels from the Brood War add-on for the PC version of the game. The Nintendo 64 all-remade version of Quake II features higher color depth and better performance, but not a higher resolution when using the Expansion Pak. Finally, in the vast majority of games with support, such as Castlevania: Legacy of Darkness and Indiana Jones and the Infernal Machine, the expansion pak is merely used as additional framebuffer memory to enable various high-resolution (usually interlaced) mode options, at the downside of usually worse performance, in some cases dramatically so. This common simple use of the Expansion Pak can be attributed to ease of implementation and the fact that games still mainly targeted the stock N64 configuration; also, the additional RDRAM could not be easily used to circumvent other bottlenecks of the console, such as the small texture cache.[citation needed] Also, the original NTSC release[citation needed] of Space Station Silicon Valley is known to potentially crash in certain places if the Expansion Pak is present.[16]
IGN celebrated the Nintendo 64 industry's methods in launching and supporting the Expansion Pak, for making a high impact accessory with "immediate and noticeable" effects but which is nonetheless mostly optional
