Abstract: An apparatus and method for improved servo control in a disc drive. A rotatable disc has first, second, third and fourth radially staggered servo burst patterns which define a plurality of concentric tracks. An actuator assembly supports a transducing head adjacent the tracks. A servo circuit combines respective at least third order polynomial functions of burst signals from the first and second, and third and fourth, burst patterns to generate a continuous function position error signal (PES) with normalized absolute magnitudes of 0 when the head is positioned at track centers, 0.5 at track boundaries, and 0.25 at quarter-track locations, and with substantially linear slope therebetween. The servo circuit applies current to an actuator motor to position of the head relative to a selected track in relation to the magnitude of the PES.

Abstract: A temperature sensing system for use in a computer disc drive comprises a themoelectric sensor having an output sensor voltage which is variable as a function of temperature, an interface circuit adapted to receive the output sensor voltage from the thermoelectric sensor and adapted to generate a scaled and level-shifted analog output voltage signal, and an analog-to-digital converter circuit adapted to receive the analog output signal voltage from the interface circuit and convert the analog output signal voltage into a digital signal which is compared to various defined thresholds.

Abstract: Method and apparatus for dynamically compensating for servo burst measurement offsets in a disc drive. A first type of servo position error signal is used during a compensation routine to position a head adjacent a selected track on a disc, the first type of servo position error signal determined from servo burst signals read by the head from servo position fields on the disc. A second type of servo position error signal is also generated from the servo burst signals and the difference between selected values of the second type of servo position error signal is compared to an acceptance limit. Compensation terms are incrementally added to the servo burst signals used to generate the second type of servo position error signal until the difference is below the acceptance limits. Thereafter, the compensation terms are stored and retrieved during normal track following operations to generate a compensated servo position error signal.

Abstract: A data storage system comprised of a plurality of disc drives which each comprise a plurality of data storage discs rotated by a polyphase motor. Each disc drive has a servo system for radially positioning transducer heads proximate the disc surfaces and generating an index signal for a selected orientation of the discs. A reference signal generator in each disc drive produces a reference signal at each of a succession of time intervals equal to the desired period of rotation of the discs and the disc drives are interconnected to enable each disc drive to sense a reference signal generated by any other disc drive. Each disc drive includes a microcomputer that is periodically interrupted and, during the interrupt, transmits the reference signal generated by the disc drive to the other disc drives in the absence of reception of a reference signal from another disc drive prior to the interrupt to provide a common reference signal for all of the disc drives.