The two 9-pin D-type connectors with pins (male) are used to
interface to four types of devices:

    1.  Mouse or trackball, 3 buttons max.
    2.  Digital joystick, 2 buttons max.
    3.  Proportional (pot or proportional joystick), 2 buttons max.
    4.  Light pen, including pen-pressed-to-screen button.

The connector pin assignments are discussed in sections organized
by similar hardware and/or software operating requirements as shown
in the previous list.  Signal names follow those used elsewhere
in this appendix, when possible.

    J11 is the right controller port connector ( joy1dat , pot1dat ).
    J12 is the left controller port connector ( joy0dat , pot0dat ).

   NOTE:
   -----
   While most of the hardware discussed below is directly accessible,
   hardware should be accessed through ROM kernel software. This will
   keep future hardware changes transparent to the user.

 mouse/trackball        proportional controllers 
 digital joysticks      light pen 
 fire buttons