I found this out for myself as a kid by taking a 2600 joystick apart to figure out how to wire it to my LEGO Mindstorms kit. By carefully choosing resistor val

I found this out for myself as a kid by taking a 2600 joystick apart to figure out how to wire it to my LEGO Mindstorms kit. By carefully choosing resistor values for the four cardinal directions, I could read 8 unique resistance values out for the cardinal and diagonal directions at a single analog I/O port on the RCX brick for control. It was a huge boon to me that it used simple contact closures and not a digital serial protocol!