A motor drive system for operating a mechanism for raising and lowering a window covering to which a continuous cord loop is coupled, the motor drive system comprising: a motor configured to operate under electrical power to rotate an output shaft of the motor, wherein the motor is external to the mechanism for raising and lowering a window covering; a drive assembly configured for engaging and advancing the continuous cord loop, wherein advancing the continuous cord loop in a first direction raises the window covering, and advancing the continuous cord loop in a second direction lowers the window covering; a controller for providing positional commands to the motor and the drive assembly to control the advancing the continuous cord loop in the first direction and the advancing the continuous cord loop in the second direction; and an input-output device for the controller, including an input interface that receives user inputs along an input axis to cause the controller to provide the positional commands to the motor and the drive assembly, and further including a visual display aligned with the input axis of the input interface, wherein the drive assembly comprises a driven wheel configured for engaging and advancing the continuous cord loop coupled to the mechanism for raising and lowering the window covering, and a coupling mechanism coupling the driven wheel to the output shaft of the motor and configured for rotating the driven wheel in first and second senses, wherein rotation of the driven wheel in a first sense advances the continuous cord loop in the first direction, and rotation of the driven wheel in a second sense advances the continuous cord loop in the second direction, and wherein the controller provides the positional commands to the motor and the coupling mechanism to control the rotation of the driven wheel in the first and second senses. a motor configured to operate under electrical power to rotate an output shaft of the motor, wherein the motor is external to the mechanism for raising and lowering a window covering; a drive assembly configured for engaging and advancing the continuous cord loop, wherein advancing the continuous cord loop in a first direction raises the window covering, and advancing the continuous cord loop in a second direction lowers the window covering; a controller for providing positional commands to the motor and the drive assembly to control the advancing the continuous cord loop in the first direction and the advancing the continuous cord loop in the second direction; and an input-output device for the controller, including an input interface that receives user inputs along an input axis to cause the controller to provide the positional commands to the motor and the drive assembly, and further including a visual display aligned with the input axis of the input interface, wherein the drive assembly comprises a driven wheel configured for engaging and advancing the continuous cord loop coupled to the mechanism for raising and lowering the window covering, and a coupling mechanism coupling the driven wheel to the output shaft of the motor and configured for rotating the driven wheel in first and second senses, wherein rotation of the driven wheel in a first sense advances the continuous cord loop in the first direction, and rotation of the driven wheel in a second sense advances the continuous cord loop in the second direction, and wherein the controller provides the positional commands to the motor and the coupling mechanism to control the rotation of the driven wheel in the first and second senses.