 They produced cartridges that fit in the video game console's cartridge slot, but were interfaced with a floppy disk drive through a connecting cable.The copier, as they were called, also had a passthrough slot into which a real game could be inserted.The device, once powered up, could be used to copy the cartridge's ROM data into files on ordinary MS-DOS formatted 3.5" floppy disks and thereafter to play the game from the same disks, without having to rely on the original cartridge being present.