RCX Input Mux and Color Sensor

RCX Input Mux and Color Sensor: "A multiplexer works by connecting multiple sensors to a single input one at a time. Most computers employ a multiplexer in their analog to digital conversion hardware to save space and money. In fact, the RCX has a multiplexer, but only three inputs are available for the user. The RCX uses one of the other channels internally to read its own battery voltage."