If you look at
http://upload.wikimedia.org/wikipedi...FlightDeck.JPG
and zoom in on the rear of the centre console you will see the map display control panel immediately in front of the Nav 3 display and APU temp gauge. IIRC the system was told the general orientation of the map centreline (in this case "C" "1" and the pen could be driven about the map with the 4 pushbuttons - left/right moved the pen horizontally and up/down moved the map roll. The Doppler controller is to the right of the APU Temp.