There should be a part of RAM that can be read and written to by more than one game. This could work by a host cart having a whitelist of guest cart IDs that can use the shared RAM with the host game, and the guest carts have the ability to access the shared RAM from the get-go. This could be used by a Zelda clone where the game is split across multiple carts (like Picoware, but items have to persist between carts, so the host cart (the boot cart) puts the item data in the shared RAM, which the other guest carts can access and edit.

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