The GameCube Memory Card is a propriety flash-based memory device used to save data for games on the Nintendo GameCube. Up to two memory cards can be inserted into a GameCube at once.
Nintendo officially released three different cards with differing sizes for the GameCube: 59 blocks (512 kilobytes, grey in color), 251 blocks (2 megabytes, black in color), and 1019 blocks (8 megabytes, white in color). Some third-party manufacturers also released cards that were larger in capacity than any of Nintendo's official products.
GameCube memory cards are backwards compatible with the Wii; intended for saving GameCube games, some Wii games did have the ability to read data from the memory cards.
Like most other GameCube games, F-Zero GX requires a memory card as to save the player's data and progress; furthermore, the player's Garage data, custom emblems, ghosts, and Replays can be saved to the memory card. The game automatically loads data when it is first booted, though save data from other cards can be loaded via the game's options menu. While the game can be started without a memory card, it cannot save any data, and the player is warned of this fact before starting gameplay; furthermore, attempting to insert a memory card with pre-existing game data after this point will prevent the game from saving the data.
The number of blocks taken up by F-Zero GX depends on how much the player saves. GX's save data by itself takes up 4 blocks; Garage data, however, takes up 18 blocks, ghosts and emblems take up 3 blocks apiece, and replays can take anywhere from 3 to 13 blocks apiece, depending on the complexity and length of the replay.
F-Zero GX's default save data is only loaded from the memory card inserted in Slot A; garage, emblem, ghost, and replay data, however, can be loaded from either slot.
F-Zero GX's default save data is notably "locked" to the memory card that it was originally written on, and neither the GameCube nor Wii can natively move or copy this data from one memory card to another; homebrew available for both consoles, however, can bypass this limitation. Save data for garage, ghosts, emblems, and replay are not affected by this limitation and can freely be moved or copied onto other memory cards. The exact reason for why GX's data is locked is unknown, though it is theorized that it was an attempt to prevent players from distributing unlockable data from F-Zero AX.
F-Zero AX's arcade cabinets uniquely feature a slot where players can insert the GameCube's memory cards, allowing for the cabinet to read data from and write data to the card. Doing so allowed for access to the player's existing Garage data, as well as allowing for the player to more easily unlock several bonuses in F-Zero GX, including custom parts and racers.