Joystick / Game Port (201h)

	|7|6|5|4|3|2|1|0|  Port at 201h used with Joysticks
	 | | | | | | | `---- joystick a, x coord (0 = timing active)
	 | | | | | | `----- joystick a, y coord (0 = timing active)
	 | | | | | `------ joystick b, x coord (0 = timing active)
	 | | | | `------- joystick b, y coord (0 = timing active)
	 | | | `-------- joystick a, button 1 (0=pressed)
	 | | `--------- joystick a, button 2 (0=pressed)
	 | `---------- joystick b, button 1 (0=pressed)
	 `----------- joystick b, button 2 (0=pressed)

	|7|6|5|4|3|2|1|0|  Port at 201h used with Paddles
	 | | | | | | | `---- paddle a coord (0 = timing active)
	 | | | | | | `----- paddle b coord (0 = timing active)
	 | | | | | `------ paddle c coord (0 = timing active)
	 | | | | `------- paddle d coord (0 = timing active)
	 | | | `-------- paddle a, button (0=pressed)
	 | | `--------- paddle b, button (0=pressed)
	 | `---------- paddle c, button (0=pressed)
	 `----------- paddle d, button (0=pressed)


	- accessed through port 201h
	- bits 3-0 are resistive inputs with the length of the pulse
	  determined by 0-100K ohm resistive load.   Use this formula:

	time = 24.2æ + ( 0.011æ * resistance )
	or
	resistance = ( time - 24.2 ) / 0.011


	- a read should be immediately preceded by a write (any data)
	  to start timing for the resistive values.