Burst comparison and sequential technique for determining servo control

Abstract

A burst magnitude comparator and an instruction sequencer are employed in a servo system controller to rapidly determine position correction information for moving a transducer head over the center line of a track recorded on a disk in a mass storage disk drive. The burst magnitude comparator selects at least two burst signals derived from bursts recorded at predetermined locations relative to the center line from which to derive a correction control signal, based on a predetermined relationship of the burst signals, and supplies the selected burst signals in a predetermined order to facilitate calculation of the correction signal by a data processor used with the servo system controller. An instruction sequencer controls a sequence of converting the analog burst signals from the head to digital burst signals without intervention or control from the data processor. By ordering the signals with the burst magnitude comparator and by sequencing the conversion of the signals, the calculation is speeded and the processing and code requirements for the data processor are greatly reduced, thereby reducing transport delay and freeing the resources of the processor for use in other, potentially more important tasks associated with the servo controller.