Off-set nulling system and method for computer disk drives

An off-set nulling system for detecting and compensating for position off-set error of a head (12) relative to a centre line (23) of a designated track (24) on the surface of a memory storage disk (14) having a plurality of generally concentric tracks, the head being movable through a seek step during a normal operation mode for alignment with the designated track (24), comprises: calibration mode means for detecting and compensating for position off-set errors during a calibration mode at selected tracks located respectively at radially inner and radially outer regions on the disk surface; and operation mode means responsive to the specific location of the designated track (24) on the disk (14) and the position off-set errors detected by the calibration means for interpolating the position off-set errors to apply an interpolated off-set to the head for compensation of position off-set error at the designated track.