Abstract: A predictive failure control circuit and associated method are provided in a data storing and retrieving apparatus. The circuit is configured to schedule a data integrity operation on data associated with a subportion of a data storage space, in relation to a comparison of an accumulated plurality of executed host access commands associated with the subportion. The subportion can comprise a sector or a single track or a band of tracks. A table preferably stores accumulated number of host access commands for each of a plurality of subportions of the data storage space. The data integrity operation can comprise reading the data on to detect degradation and restoring the recovered data to the same or to new, different tracks. The data subportions can also be reallocated to a new location.

Abstract: A method and system for generating a position signal indicative of the position of a transducer with reference to a fixed reference point on the surface of a disk within a disk drive system. The system is comprised of two major elements. The first element is a disk divided into sectors and has Z data tracks where each sector includes a preamble area that includes a servo band comprised of 0.75*Z consecutive overlapping quadrature servo patterns and gray scale band comprised of 1.5*Z consecutively addressed gray scale areas that have been recorded across all data tracks. The second element is a position generator that generates the position signal from the relative magnitude of each of the four servo bursts of a quadrature servo pattern of the servo band and the gray scale address of the gray scale area of the gray scale band that is read by a transducer when the transducer reads the preamble of a sector.

Abstract: An automatic velocity calibrator for a head positioning servo system in a magnetic disk drive performs a velocity calibration in a single pass over the magnetic disks by measuring actuator velocity and adjusting the gain of the velocity transducer in a series of successive approximations. Velocity is determined by turning a timer on in response to a track crossing and turning the timer off after at least two successive track crossings have been detected. A plurality of velocity measurements are stored and averaged. The average velocity is compared to a constant velocity command and an 8-bit latch is incremented or decremented in response to this comparison. A digital to analog converter produces a reference for an automatic gain control amplifier in the servo system which in turn adjusts the velocity transducer gain.