Patent ID: 7035038

Claim:
A magnetic disk unit operable to rotate a disk-shaped magnetic recording medium having a reference track and a plurality of data tracks with a motor, which generates an index signal at a predetermined position, and to record or reproduce data by employing a magnetic head, said magnetic disk unit comprising: a head moving unit operable to slightly move the magnetic head in the direction of the radius of the disk-shaped magnetic recording medium in a predetermined unit of a distance that is shorter than the width of a data track on the disk-shaped recording medium; a reproduction output amplitude measuring unit operable to measure the reproduction output amplitude of a signal read from the data track by the magnetic head each time the index signal is generated; and a CPU operable to obtain a position where the reproduction output amplitude has the maximum value based on the reproduction output amplitude measured by said reproduction output amplitude measuring unit and the number of head movements of the magnetic head as moved by said head moving unit so as to perform control of data track positioning of the magnetic head on the data track.