I had a thought relating to the developement of a sellable cart, could a basic cart board (basically to connect to the nes only) be made without the memory onboard and a connection to the pc (pci card / usb / serial / parrallel) via a cable. Not having memory on the cart is so that a driver / program would allocate the cart memory from the pc and also control the swapping of memory in and out of nes memory (perhaps support mapper 0 and 1 (I think these should cover what most would want) via the drivers)
The cart to pc connection would though have to be fast enough to transfer data across though (for mapper 1, would'nt matter for mapper 0) on the fly so for mapper 1 and up a usb cable (or network cable (to go in a pci card)) would be needed - should be able to transfer over 10kbytes a frame - if mapper 0 used only, then a serial cable could be used and perhaps this could make this cheaper to produce than having memory + controlling software on the cart - anyone have any thoughts on the possibility of this sort of design?