I would have passed it if it wasn't for the 7 pin NES controller port on the back. See pictures below. It has 2 female sockets and 1 male plug on the back. The plug and one socket are both large 5 pin DIN connector. The middle one is the 8 bit NES controller port. Inside the device are 2 chips and few components but I can't reverse engineer it because one chip is labeled only as "JM 1"so it may be a property chip. The other chip is a CMOS 4066 quad analog switch and it appears to control connection between the 2 input sockets possibly to select either NES controller port or the 5 pin port..
3 buttons and 3 indicator LED for reset, set, and load. It measures about the same as 2 deck of cards stacked.
What is it?













