Motion controller: The chip in the middle of the motor controller circuit board is the MCU. Below-left is a logic inverter. And below-right is a dual H-bridge (TI SN754410NE) motor driver circuit. The board also has passive noise and interface parts.

The little green board is a voltage level shifter that converts between the 5-volt serial levels of the MCUs and the standard voltage levels of RS-232 serial.