The original NES was fairly simple. The power has a plug in the rear of the system. Right next to the power input there is a small hole for the video output. With the NES systems this was a standard AF Adapter that plug into the coax on your TV.
With the older Nintendos, like the first one and Super, there will be a large lack power pack which goes into a wall socket, and then there is a thinner cord which will hook onto the cable outlet on the back of the TV.
