In short, it's a pretty rare bit of kit. Even more so is the 64DD Development Kit — the console Nintendo sent to studios ...

It was going to be for the Nintendo 64DD, but was canceled early in production due to lack of progress and the commercial failure of the 64DD add-on. Only one demo level was ever made but was ...

that would have been used to connect the two Nintendo consoles. The GameBoy could have been used as a controller for the 64DD game, to check the card statistics and share data with a presumed ...