Well, as far as I know, you need a V64 to use the DS1, but the DX256 will work independant of it. (pretty sure).. The DX256 has 256 memory slots on it, you just turn the knob to the one you want to use, and powerup the n64 with it piggybacking the cartridge, and it will use the dx256 memory instead of the cartridge's. This was valuable especially with the v64 because while you were playing many different games, you only otherwise had one host cartridge you were using for them all, and one game would write over your saves for the other. The DS1 is for a different memory used in some later N64 games, and I am unsure if it has use beyond giving the v64 the ability to save in these games. Anyone with more info or corrections to mine feel free to add to this. :)