A modular digital robot control includes an electronic arm interface board provided with circuitry for performing robot arm dependent functions. Included are circuitry for generating power amplifier control signals in response to input voltage command signals and circuitry for processing and manipulating position, velocity and motor current feedback signals.An electronic torque processor board is provided with paired torque microprocessors for operating each of respective torque control loops for respective robot joint motors. The torque microprocessors generate the voltage commands in response to input torque commands and feedback motor current signals.An electronic servo control board is provided with paired position/velocity microprocessors for operating position and velocity control loops for the respective joint motors. The position/velocity microprocessors generate the torque commands in response to input position commands and feedback position and velocity signals. The servo control board further includes system resource facilities providing general support for the operation of the microprocessors and includes a DMC controller and two asynchronous controllers for communications interfacing with local input/output devices and other systems and devices.When executed in one of the position/velocity microprocessors, a stored motion program uses trajectory planning and interpolation to generate position commands in accordance with predefined moves set forth in a robot program. The servo control, torque processor and arm interface boards are interconnected to provide a complete basic control for the robot joint motors. An optional fourth electronic board can be connected to the basic control. It is called a system board and it includes paired system microprocessors that execute the motion program enabling the expanded control to provide extended robot control performance.