Each Amiga has two  nine-pin connectors  that can be used for input or
output with a variety of controllers.  Usually, the  nine-pin connectors 
are used with a mouse or joystick but they will also accept input from
light pens, paddles, trackballs, and other popular input devices.

Figure 8-1 shows one of the two connectors and the corresponding face-on
view of a standard controller plug, while table 8-1 gives the pin
assignments for some typical controllers.

     figure 8-1: controller plug and computer connector 


                  Table 8-1: Typical Controller Connections

                       Mouse,
                     Trackball,  Proportional      X-Y
                      Driving     Controller   Proportional
  Pin    Joystick    Controller     (Pair)       Joystick    Light Pen
  ---    --------    ----------  ------------  ------------  ---------
  1      Forward     V-pulse       ---           Button 3**  ---

  2      Back        H-pulse       ---           ---         ---

  3      Left        VQ-pulse      Left button   Button 1    ---

  4      Right       HQ-pulse      Right button  Button 2    ---

  5*     ---         Middle        Right POT     POT X       Pen pressed
                     button**                                to screen

  6*     Button 1    Left button   ---           ---         Beam trigger

  7      ---         +5V           +5V           +5V         +5V

  8      GND         GND           GND           GND         GND

  9*     Button 2**  Right button  Left POT      POT Y       Button 2**


                *  These pins may also be configured as outputs
                ** These buttons are optional


 registers used with the controller port 
 reading mouse/trackball controllers 
 reading digital joystick controllers 
 reading proportional controllers 
 reading a light pen 
 digital i/o on the controller port