Abstract: A magnetic tape-transport system wherein the speed of a capstan used to transport magnetic tape past a read-write head is controlled utilizing digital techniques. A comparator is provided a first digital input indicative of desired speed and a second input from a counter which counts up or down until the count equals the first digital input. The counter output is converted to an analog voltage and applied to a summing junction point which also receives a voltage which is proportional to the instantaneous speed of the capstan drive motor. The voltage difference at the summing junction point is used to drive the capstan drive motor.

Abstract: A tape reel servo control system for use with a tape transport system wherein tape loop position within vacuum loop boxes is maintained by digital techniques as opposed to analog techniques. In normal operation when the tape loop deviates from an equilibrium position in one direction within a loop box, its associated reel is accelerated to move it back to its equilibrium position by means of a series of motor drive pulses whose pulse lengths are determined by the count registered in a counter wherein the count is varied in accordance with the difference between actual and required acceleration of the reel. When the tape loop deviates from the equilibrium position in the other direction, the reel drive motor is braked by electronically shorting its terminals until the tape loop moves back to its equilibrium position.