The RCX microcomputer is the brain of the LEGO^® MINDSTORMS^® for Schools system. It receives programs for the ROBOLAB™ software (Windows or Mac) via an infrared computer link and stores up to five programs at a time. The RCX then runs the programs when activated.

Up to three inputs can be used by the RCX to sense events in its environment, which in turn can determine what the three outputs will do to react to the sensing data. Requires six AA batteries or AC adapter, sold separately.