I believe that if you look at the schematics, you'll find the diagram for each of the possible plugs. I don't have the Star Wars schematics handy, but I've got the Missile Command ones here and it does have each plug's wiring diagram. I think that's the manual a previous poster was referring to.
If you don't have the schematics and the manual for your game - GET THEM. Most things have been scanned if you can't find an original, but get them, one way or another. Life is much easier when you can refer to the docs first, and use them as a basis for asking questions.