     $DC00/56320/CIA1+0:   Data Port Register A (Keyboard, Joystick, Paddles)

       +----------+---------------------------------------------------+
       | Bits 7-0 |   Write Keyboard Column Values for Keyboard Scan  |
       | Bits 7-6 |   Paddles on: 01 = Port A, 10 = Port B            |
       | Bit  4   |   Joystick A Fire Button: 0 = Pressed             |
       | Bit  3   |   Joystick A Right: 0 = Pressed, or Paddle Button |
       | Bit  2   |   Joystick A Left : 0 = Pressed, or Paddle Button |
       | Bit  1   |   Joystick A Down : 0 = Pressed                   |
       | Bit  0   |   Joystick A Up   : 0 = Pressed                   |
       +----------+---------------------------------------------------+

       Do NOT use Paddles on both Ports at the same time!

       Joystick A is the one plugged into Port 2.

       Default Value: $7F/127 (%01111111)

    Kernal-Reference:

     STA $DC00   : $E93A $E945 $EA90 $EAA5 $EAD7 $EB44 $F6D4 $FDAB
     STX $DC00   : $F6C9