Hacker International's Famicom game copier, they advertised in a Japan Gaming magazine until Nintendo put a stop to it.
Comment by Gregory Chiasson: This device is a 2 way FamiCom Disk System RAM adapter, two cables bring two fds together, where with the right software called "hacker" it'll load one side into ram, then copy to the other FDS. Comment by kyuusaku: Hacker for famicom does not copy games, only Famicom disks. There are two models, one that is a self contained unit, it does not need an actual Famicom, just get 2 FDS drives and copy. The other hardware they released is just a cable that connects to the unused FDS RAM adapter expansion port, that connects to another FDS and works with the appropriate software.