A variable reluctance motor of the stepper type is operated as a brushless constant speed DC motor by sensing the position of the rotor during rotation and generating a tachometric signal representing the speed of the rotor in response to the sensed position of the rotor. The tachometric signal is compared with a reference signal to generate a supply voltage to the windings of the stepper motor which will maintain the speed of the rotor substantially constant. The windings of the stepper motor are sequentially energized by the supply voltage in response to sensed position of the rotor. During start-up and prior to the time the motor reaches the predetermined speed, a start-up signal is utilized in addition to the sensed rotary position to sequentially energize the windings with the supplied voltage. The motor is utilized to drive a floppy magnetic data storage disc.