Abstract: A direct access storage device (DASD) employs a servo including a digital signal processor having a software switch (DSP). The DSP is provided with DSP code in a DSP code space. One of the functions of the DSP code is to implement the microstep calibration of the present invention. Microstep calibration is accomplished by a step change of head position within a single track. In head position 1 the head is at the center of the track in track follow mode. From head position 2 to head position 3, an offset command causes the servo to move the head slightly off center. From head position 3 to head position 4, the servo is disabled by opening the software switch in the DSP. The position delta, delta 3-4, of the head is recorded. From position 4 to position 6, the servo is still disabled and a step of current is applied to the VCM to determine position delta 2. From position 7 to position 8, the servo is still disabled and two steps of VCM current are applied to recover to the offset position.