The invention relates to control of a direct current machine (such as a three-phase electric motor) by means of a microprocessor. In certain applications of a three-phase alternating current motor, the use of a microprocessor to control the speed and torque of the motor is desired. The speed and torque requirements of the motor can be met by the microprocessor being fed a suitable combination of proportional-integral (PI) and feedback signals representing the speed and torque of the motor. These signals are generated by suitable devices such as hall effect sensors and tachometers. However, in many applications where a three-phase alternating current motor is used it is necessary to make additional modifications to the basic motor which can make the use of a microprocessor very difficult. For example, if three individual polyphase alternating current drives are required for controlling three separate axes, such as for a three axis positioner, conventional motor wiring must be modified for the control system. If a microprocessor is used, wiring for the processor must also be modified to accept the outputs from the various motor sensors. In addition to the need to connect the sensor outputs and processor inputs, a special external communications link must be used between the microprocessor and the motor. These requirements make the use of a conventional microprocessor very difficult and the potential advantages of a microprocessor control system lost or compromised. Accordingly, there is a need for a system and method which permits the use of a microprocessor for controlling a three-phase alternating current machine in applications where the microprocessor normally could not be used.