A track locating servo system utilizing the data heads as absolute position transducers

Magnetic transitions may be compactly written in the normally unused deadspace between the data sectors on each data surface of a moving head disc drive, which may be read by ordinary data heads to obtain absolute position information for use by the track locating servo. A track following system which complements the track locating system is briefly described. Implementation of these techniques eliminates both the need for a servo surface or external encoder, and troublesome reference surface to data surface mechanical tolerance problems.