If the heart of the robot is the power subsystem, then the brain must be the logic subsystem’s microcontroller module. The microcontroller controls both the flow of information and power in the robot. It interfaces with the motors, sensors, the RF receiver, and the programming module through ports located on both the top and back side of the module.
There are three banks of ports on the top of the module. The bank of 8 outputs on the bottom left are for motors only. Directly above them are 6 interrupts. On the right are 16 multipurpose digital/analog input/output ports.
Although the microcontroller is preprogrammed with behavior for the motors and bumper & limit sensors as used by the squarebot example from the manual, its software can be completely reprogrammed using the programming kit sold separately.