Abstract: A signal reproducing method reproduces servo information recorded on a recording medium by use of a head. A current calculation related to a current and an observer calculation related to a position and a velocity of the head are made based on reproduced servo information, and a current value for driving the head is calculated based on the above calculation result. Only computations which require a demodulation result of a present sample are made during a first time after demodulation of the position of the head to a time when the current value is output, and computations which require a demodulation result of a past sample are made during a second time other than the first time.

Abstract: Embodiments of the present invention allow for controlling a microactuator based at least in part on an output of a temperature sensor. Also, embodiments of the present invention allow for adjusting a control of a microactuator so as to compensate for changes in a gain of the microactuator due to changes in temperature.

Abstract: A rate of occurrence of off-track write events is determined. A seek function control parameter for a head is adaptively adjusted based on the determined rate of occurrence of the off-track write events. Related circuits and devices are also discussed.

Abstract: A head position control device controls the position of a head with respect to a disk where post code is assigned to a servo frame. Servo frames of a disk is constituted by a servo frame not having a post code recorded in an inner side zone and a servo frame having a post code recorded in an outer side zone. The device reads the servo frame, demodulates a current position from the servo frame, drives an actuator according to the modulated position, and controls the position of the head to a target position. While implementing a high TPI, the inspection time for post codes can be decreased with a servo frame occupying ratio in consideration of the data format.

Abstract: A disk drive includes a disk, a head, an actuator, and a servo controller. The servo controller controls a movement of the actuator based on a super silent seek profile to cause the actuator to perform a super silent seek in which an acoustic output due to the movement of the actuator is imperceptible to human listeners. A maximum jerk of the super silent seek profile may be less than a maximum jerk of a silent seek profile divided by ten. A snap associated with the super silent seek profile may be always less than a particular snap level, such that any change in the jerk associated with the super silent seek profile is gradual. The disk drive may further include a main controller that is configured to receive a command from an operating system, a user, and the like to perform a seek in a super silent seek mode.

Abstract: A disk drive is disclosed having hybrid spindle speed control. The disk drive includes a disk having a plurality of servo wedges, and a spindle motor for rotating the disk at an operating speed. The spindle motor generates a back electromotive force (BEMF) voltage. In operation, the disk rotation is maintained at the operating speed during a track following operation by updating, in a wedge spindle speed control mode, the spindle control current in response to a wedge speed error. Before executing a high-speed seek, the disk drive is switched to a BEMF spindle speed control mode, and the disk rotation is maintained at the operating speed during the high speed seek by updating the spindle control current in response to a BEMF speed error signal generated based on the BEMF voltage. During a seek-settle time, the disk drive is switched back to the wedge spindle speed control mode.

Abstract: Embodiments in accordance with the present invention provide a disk drive capable of verifying whether the speed of an actuator is true or not, the speed being detected while the actuator is being moved between a retracted position and a recording surface of a magnetic disk, and to provide a control method for controlling the disk drive. In a particular embodiment, a hard disk drive (HDD) comprises: a head for accessing a disk; an actuator for supporting the head, the actuator being driven by a voice coil motor (VCM); a speed monitor for, on the basis of a cylinder ID written to the disk, monitoring the speed of the actuator while the actuator is being moved between a ramp which is provided outside a data area of the disk and the data area; and a speed verifier for, if an abnormal speed condition of the actuator is detected by the speed monitor, verifying the abnormal speed condition on the basis of the counter electromotive voltage of the VCM.

Abstract: Embodiments of the invention efficiently conduct servo corrections for preventing error propagation during SSW. In an example of the present invention, a servo position signal generator generates a servo position signal indicative of the current position of a read element on the basis of a servo signal from a servo channel. A target position generator generates correction data from multiply and add operations between the PES generated when the track that the read element is following is written, and pre-registered correction coefficients. A correction target position is generated from the correction data and a reference target position, and then output to a position error calculator. The position error calculator generates a position error signal (PES) from the servo position signal and the target position signal, and outputs PES to a servo controller.

Abstract: A disk drive controller including a differential voice coil motor control function is disclosed. The differential voice coil motor control function includes an on-chip compensation network for the inner control loop, including a resistor formed of one or more MOS transistors connected in series. The gate of the MOS transistors in the compensation network is driven with a bias voltage based on a tuning current, where the tuning current is derived so that it varies with process and temperature variations of the integrated circuit, for example with variations in an on-chip capacitor. The on-chip compensation network can be tuned with sufficient precision to properly compensate the inner control loop to provide the desired frequency response in driving the voice coil motor in the disk drive.

Abstract: The Invention provides a motor drive semiconductor integrated circuit for driving and controlling a voice coil motor that can conduct a seek operation, a track follow operation and a settling operation through PWM control, has desired control accuracy and can be produced by a CMOS process. In a voice coil motor drive circuit (200) for executing positioning control of a magnetic head by feedback-controlling a driving current of a voice coil motor (108) for moving a magnetic head (106) over a magnetic disk for reading information from a storage track on the magnetic disk driven for rotation while a read state of the magnetic head is being monitored, head movement control such as a seek operation, a track follow operation etc, of the magnetic head is executed by PWM driving on the basis of a command value from a controller.

Abstract: An access performance adjusting method is adapted to a storage apparatus having a storage to prestore a skew quantity that is used to shift a data write starting position of each track of a recording medium depending on a head moving time required to move a head from one track to another track during a sequential access in which a plurality of tracks of the recording medium are accessed sequentially. The method includes measuring an apparatus performance with respect to a combination of the head and the recording medium, calculating a skew adjusting quantity with respect to the combination based on a reference apparatus performance and the measured apparatus performance, and adjusting the skew quantity read from the storage by the skew adjusting quantity and storing the adjusted skew quantity in the storage as an updated value of the skew quantity.

Abstract: In a settling judgment method for judging whether an object is settled in a target position, the settlement is judged accurately at high-speed. In a positioning device for controlling a position of an object using a position error between a target position and a current position, a plurality of judgment blocks, each of which has a different judgment slice value and continuous sample count, are created in a settling judgment block for judging whether the object is settled within the positioning accuracy range of the target position, the judgment value of the position error computed by the judgment formula is judged in each judgment block each having a different judgment slice value and continuous sample count respectively, and OR of the judgment results is output. According to the settling judgment formula, settling can be judged accurately at high-speed, and both improvement of positioning accuracy and high-speed judgment can be implemented.

Abstract: An optimal track zero determination method used in a hard disk drive and a hard disk drive using the method. The method has the operations: (a) performing a sequential seek operation on target tracks of a disk, in units of predetermined numbers of tracks, outwardly, from a track separate from a physical track zero position obtained in a servo track write operation, by a predetermined distance toward the physical track zero position; (b) determining whether the target tracks belong to a region where a track-following operation is normally performed, and determining whether an actuator arm connected to a transducer is in contact with a mechanical buffering unit during the sequential seek operation of operation (a); and (c) selecting as a logical track zero, the target track belonging to the region where the track following operation is normally performed and the actuator arm is not in contact with the mechanical buffering unit.

Abstract: In a method of feedback control for active damping of slider air bearing vibrations in a hard disk drive slider, a slider is isolated from ground. A slider velocity signal is filtered to acquire a vibration signal. The vibration signal is adjusted in amplitude to achieve an amplitude adjusted vibration signal. The amplitude adjusted vibration signal is applied to the slider to actively dampen air bearing vibrations in the slider.

Abstract: The present invention has been made to provide a control apparatus, a storage apparatus, and a head control method capable of preventing a use of a correction value that has improperly been read out. A control apparatus according to the present invention uses a correction value for head position written in a recording medium to control head position. The apparatus comprises: an allowable range acquisition section that acquires a correction value allowable range which is a previously set allowable range of a correction value; and a head position control section that controls head position using a read out correction value in the case where the correction value that has been read out from the recording medium falls within the correction value allowable range acquired by the allowable range acquisition section.

Abstract: Methods in accordance with embodiments of the present invention can be applied to determine a width of a data stroke along a rotatable medium of a data storage device. In one embodiment, the width can be determined by measuring a distance from a marker zone edge of a template pattern to a ramp, and measuring a distance from the marker zone edge to an inner crash stop. A track layout can be determined based on the width of the data stroke.

Abstract: In a data handling system having a radially-dependent track incongruity between data surfaces, at least some tracks are logically mapped so that tracks on different data surfaces correspond with one another. The correspondence is defined by the mapping so as to shorten an average headswitch seek. For example, a logical track mapping of first and second non-coaxial track sets can be defined so as to optimize a headswitch seek within each of many intermediate logical cylinders identified in the mapping.

Abstract: Embodiments of the present invention provide a way to modify the controller of a HDD head actuator to increase the error rejection capability and suppress the wideband vibration that affects the head motion. In one embodiment, a system to suppress influence of an external disturbance to an actuator comprises a controller providing a controller output as an actuator input to drive an actuator; a feedback loop to feed a head signal at an output of the actuator back as an input to the controller to produce an error signal; and a plurality of peak filters coupled to the controller and having different peak frequencies. Each peak filter has a peak filter input including the error signal, and has a peak filter output. A supervisor module is coupled with the peak filters to selectively add or delete the peak filter output of each peak filter to the actuator input to drive the actuator.

Abstract: The periodic component of a timing mark position error of a self-servo write pattern on a disk of a disk drive is determined based on measurements that are made of the timing mark position error at selected radial track locations. The determined periodic component of the timing mark position error is then removed based on the radial location on the disk.

Abstract: A disk drive is disclosed comprising a voice coil motor (VCM) for rotating an actuator arm about a pivot in order to actuate a head over a disk. The disk is rotated by a spindle motor, and a feed-forward compensation value is computed that compensate for a non-centric alignment of the disk with respect to the spindle motor. During a calibration mode, the VCM is controlled to press the actuator arm against a crash stop, and the feed-forward compensation value is computed in response to a position error signal (PES). The PES is generated in response to embedded servo sectors recorded on the disk, wherein each embedded servo sector comprises a track address for coarse alignment and servo bursts for fine alignment.

Abstract: A magnetic disk medium of a discrete track recording (DTR) structure and a disk drive using the magnetic disk medium are disclosed. The magnetic disk medium of the DTR structure has positional-error detection servo patterns in a servo region, the positional-error detection servo patterns being formed of null servo patterns. This enables magnetic regions included in the servo region to occupy substantially 50% of the area of the servo region.

Abstract: A system includes a self-servo-write (SSW) module and a control module. The SSW module generates servo signals and a control signal. The control module generates a first current to bias an actuator arm against a spring when the control signal is received and discontinues the first current to release the spring and accelerate the actuator arm when the SSW module generates the servo signals.

Abstract: A method of use a defect measure to control spindle motor is described. A system gets the defect situation from a CD by referring a maximum time of pass through the defect and a total time of pass through the defect. According the maximum scrape and the scrape of whole CD, the system adjusts a speed of the spindle motor for reducing a bad effect upon the system. When pass through the defect, the system reduce the speed of the spindle motor for saving power consumption.

Abstract: A method and apparatus for controlling movement of a transducer to limit its stopping time at a certain position of a disk regardless of whether the disk drive performs a read/write operation, an etching or clustering effect of a lube layer coated on the disk is prevented, thereby preventing performance degradation of the disk drive.

Abstract: Methods of filtering a position error signal (PES) indicative of a position of a transducer of a disk drive include obtaining sample position data for the transducer, eliminating selected data of the sample position data to provide a subset of the sample position data, obtaining a plurality of sets of preliminary filter coefficients based on the subset of the sample position data, obtaining a final set of filter coefficients from the plurality of sets of preliminary filter coefficients, and filtering a position error signal using the final set of filter coefficients.

Abstract: A disk drive comprising an actuator including a head, a disk, and a processor connected to the actuator by a flex circuit cable. The processor under the control of a program to: apply a control signal for a seek operation and to apply a bias signal to the control signal to approximate the bias imparted by the flex circuit cable. The bias is determined from a data structure that stores: bias values for track zones representative of a first and second bias curves that approximate a bias imparted by the flex circuit cable upon the actuator as the actuator moves the head from the OD to the ID of the disk and from the ID to the OD of the disk, respectively. The bias values representative of the first and second bias curves are determined based upon a non-linear apportionment of track zones.

Abstract: A disc drive with a disc having multiple concentric data tracks. A track start point is rotationally displaced by a track skew time relative to a track start point of an adjacent concentric data tracks. The read/write head has a write settling time that is more than the track skew time. A data reordering circuit and firmware reorders write data and provides the reordered data to the read/write head after the write settling time. The reordering of the write data reduces write latency.

Abstract: A controller for a disk drive measures track misregistration, extracts non-repeatable runout from measured track misregistration, determines one or more components of non-repeatable runout at various radial locations of a disk, and compares the determined components to known values at different altitudes to determine an operating altitude of a disk drive.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. Additional bursts can also be written, such as for each data track centerline. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: A method of transferring data of one or more rotatable data storage devices includes but is not limited to rotating the at least one rotatable data storage device; transferring the data between a plurality of stationary data transfer heads and the one or more rotatable data storage devices; and using one or more computer programs to determine which of the plurality of stationary data transfer heads are to be used to transfer a first portion of the data between the plurality of stationary data transfer heads and the one or more rotatable data storage devices and the direction in which the first portion of the data is to be transferred. In addition to the foregoing, other method aspects are described in the claims, drawings, and text forming a part of the present application. Other methods and apparatuses are also disclosed.

Abstract: A disk drive is disclosed comprising a disk and a voice coil motor (VCM) for rotating an actuator arm about a pivot in order to actuate a head over the disk. During a park operation, a latching characteristic associated with latching the actuator arm is measured and used to configure a latching parameter that reduces acoustic noise. The latching parameter is used to latch the actuator arm by seeking the head to a latching track, maintaining the head over the latching track for a predetermined interval, applying an acceleration pulse to the VCM for an acceleration pulse period, applying a braking pulse to the VCM for a brake pulse period, and applying a latching current to the VCM.

Abstract: In a disk drive, a contact write current that causes head-disk contact due to pole tip protrusion is detected using a variance of a position error signal (PES). A method of determining the contact write current includes generating PES's in response to the head reading servo sectors on the disk, calculating PES variances wherein each PES variance is a statistical measure of a different group of the PES's, calculating a change in the PES variances, and selecting the contact write current in response to the change in the PES variances.

Abstract: Embodiments of the present invention are directed to methods of making a disk drive and related servo writers. The disk drive includes a data storage disk, an actuator arm, and a head connected to the actuator arm. The disk drive is connected to a servo writer that includes a push-arm that is configured to radially move the actuator arm relative to the disk. The method includes moving the push-arm of the servo writer a defined distance to push the actuator arm and position the head at a defined radial location on the disk. Servo fields are written through the head along an arc at the defined radial location on the disk. A sensor that contacts the actuator arm is used to generate an electrical vibration signal that is indicative of vibration between the push-arm and the actuator arm.

Abstract: Disclosed is a disk drive to characterize misaligned servo wedges. A disk of the disk drive includes a plurality of circumferential tracks, in which, each track includes a plurality of servo wedges spaced sequentially around the circumference of the track wherein the servo wedges may be misaligned relative to the head of the disk drive that moves about a pivot. A servo controller is used to characterize the misaligned servo wedges relative to the head during a seek operation by implementing the following operations: commanding the head to perform a seek operation from a starting track to an ending track; obtaining samples of wedge-to-wedge time (WTWT) values corresponding to time intervals between identified servo wedges for sampled tracks traversed during the seek operation; calculating WTWT variations for each sample; and calculating a calibrated misalignment value for each sample based upon WTWT variations.

Abstract: Method and apparatus for control object manipulation from an initial position to a final position. A jerk control profile describes a near time-optimal jerk trajectory for the control object and includes a sequence of first, second and third sinusoidal pulses of respectively alternating polarity and common absolute magnitude. The area of the second pulse is nominally equal to the combined area of the first and third pulses, and the pulses are preferably symmetric about the respective maximum pulse values. Associated control profiles (control voltage, current, velocity, displacement, etc.) are derived from the jerk control profile. For longer seeks, constant, non-zero jerk segments are inserted into the profile between the pulses, during which control voltage is maintained near saturation. The control object preferably comprises a transducer in a data storage device and the jerk control profile is stored in a memory location of the device.

Abstract: The thermal decay of data written to a magnetic mass storage medium is determined by measuring and analyzing the time-domain equalized-signal-to-noise ratio (ESNR) and equalized signal-to-total-distortion noise ratio (ESTDR) of written data. In some embodiments, a test track and a reference track are initialized from data. Subsequently, the reference track is re-initialized from the test data, and the time-domain ESNR and/or ESTDR measurements are made of the test track and the reference track, at predetermined time intervals. Later, the time-domain ESNR and ESTDR measurements are analyzed to determine the thermal decay of the data written. In another embodiment of the present invention, the ESNR and/or ESTDR measurements includes reading the data through a non-return-to-zero bus in phases, in which the phases are selected in sequence.

Abstract: A magnetic recording disk drive uses a phase-quadrature position-error-signal (PES) pattern and a servo signal demodulator that is insensitive to clock errors and phase-misalignment errors. The disk has angularly-spaced servo sectors, with each servo sector having radially-spaced servo tracks that contain a phase-quadrature pattern of servo blocks. A first band in each servo sector contains two generally like patterns radially-spaced in the servo track with the second pattern phase-shifted 90 degrees along-the-track from the first pattern. A second band in each servo sector is spaced along-the-track from the first band and also has two patterns like those in the first band, but with the phase shift of the second pattern being in the opposite direction to the phase shift of the second pattern in the first band. The demodulator calculates the true amplitudes of the servo signal from the measured amplitudes of the servo signals from each band to thereby remove clock errors and phase-misalignment errors.

Abstract: Embodiments of the present invention provide a method and a system for generating optimal feedforward signal for the seek control to suppress the RTV (Random Transient Vibrations) and the seek acoustic noise. One aspect is directed to a method of providing a revised feedforward signal using an adaptive filter in a feedforward control system for controlling an actuator to move a head to seek a track and settle on the track of a disk in a disk drive apparatus. The method comprises performing a seek operation of the head using an initial feedforward signal; obtaining an error signal at settling after performing the seek operation; determining filter characteristics of the adaptive filter to minimize the error signal; and implementing the adaptive filter having the determined filter characteristics in the feedforward control system to produce a revised feedforward signal for controlling the actuator for moving the head in the disk drive apparatus.

Abstract: Read-write head flying height controlled through micro-actuator assembly. Flying height controlled using DC line and ground line. Lateral position controlled using them and AC line. Micro-actuator assembly operates through three terminals coupled with these lines. Head gimbal assembly contains micro-actuator assembly mechanically coupling to slider with read-write head. Actuator arm includes at least one head gimbal assembly. Actuator arm assembly includes at least one actuator arm. Voice coil actuator includes actuator assembly. Hard disk drive containing voice coil actuator. Electrical interface circuit includes ground port, DC port, and AC port, for micro-actuator assembly. Servo controller drives micro-actuator assembly to control flying height and lateral position, preferably including electrical interface circuit. Manufacturing head gimbal assembly, actuator arm, actuator assembly, voice coil actuator, and hard disk drive, and products of these manufacturing processes.

Abstract: A servo writer that uses a clamping push pin is disclosed. The clamping push pin includes a first clamping member that is movable relative to a second clamping member. The first clamping member is spaced from the second clamping member such that a disk drive head positioner assembly may be positioned therebetween. The spacing between the first clamping member and second clamping member is then reduced such that the push pin clamps onto the head positioner assembly. The push pin may then be moved to change the position of the head positioner assembly as required for servo writing operations.

Abstract: A disk drive includes a disk for storing information, a head with a transducer that writes data to and reads data from the disk, and an AC power source. The head is suspended adjacent to the disk and a flying height gap exists at the head/disk interface. The AC power source generates an AC exciter signal across the flying height gap that discharges electrostatic charge at the head/disk interface. The head/disk capacitance can be measured based on the AC exciter signal to sense the flying height. The AC exciter signal can also alter an attraction force between the head and the disk and thus control flying height. The AC exciter signal can also be based on a flying height signal representative of the head/disk capacitance and thus the flying height.

Abstract: A disk drive provides increased read and write element widths and tolerances, and also provides reduced track widths. The head with the read and write elements has a large skew angle relative to the tracks on the disk. The skew angle reduces the effective width of the read and write elements. Based on this reduction in effective width, the physical width of the read and write elements may be increased. Furthermore, the width of the tracks may be reduced instead of, or in addition to, the increased read and write element width.

Abstract: A disk drive controls head velocity during ramp load/unload by measuring voltages across a VCM and a sense resistor in series with the VCM, calculating a back EMF voltage using the VCM and sense resistor voltages, and adjusting the head velocity using the back EMF voltage. An embodiment includes amplifying the VCM and sense resistor voltages, multiplexing the amplified voltages, digitizing the multiplexed voltages and calculating the back EMF voltage in discrete-time based on the digitized voltages. Another embodiment includes selecting between PWM and IR cancellation techniques and calculating the back EMF voltage using the selected technique.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions of the media will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. Additional bursts can also be written, such as for each data track centerline. The overall error in position should decrease as the number of passes used to write a burst pair increases. Also, additional bursts can be written in separate passes in order to further reduce position error while avoiding coherence concerns.

Abstract: A disk drive includes a rotatable data storage disk, a transducer, an actuator, and a controller. The transducer is configured to read and write data on the disk. The actuator is configured to position the transducer relative to defined portions of the disk. The controller is configured to write a predetermined magnetic polarity pattern on a buffer portion of the disk to erase data thereon. The controller also determines whether the disk drive has reached a threshold operating temperature, and to selectively direct data from a host device, which is addressed for an associated original block address on the disk, to be written to the buffer portion of the disk when the disk drive has not reached the threshold operating temperature. The controller later copies the data from the buffer portion of the disk to the original block address on the disk and then erases the data from the buffer portion of the disk.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where the edges of two servo bursts are used to define a position on the media, trimming the first burst and writing the second burst on separate revolutions will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a burst pair, each burst also can be trimmed and/or written in multiple passes. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where servo bursts are used to define a position on the media, trimming a first burst and writing a second burst on separate revolutions of the media will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a combination of bursts, each burst also can be trimmed and/or written in multiple passes. The overall error in position should decrease as the number of passes used to write a burst combination increases. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: Systems and methods in accordance with embodiments of the present invention can be applied to determine the position of a ramp relative to an actuator. In one embodiment, a system in accordance with the present invention includes a rotatable medium having a first track assigned to a track located a distance from the ramp, rather than a distance from an average acquire track, thereby maximizing the size of a data region. A track density can be reduced for a given hard disk drive capacity, or alternatively the hard disk drive capacity can be maximized for a given track density.

Abstract: Disclosed are methods and apparatus for digital control of a head-disk assembly actuator with dynamic velocity compensation. In preferred methods of the invention steps are disclosed in which, the actuator voltage in an HDA is sampled and a velocity error is determined. The voltage applied to the actuator is compensated for the velocity error. Disclosed methods of the invention also include steps for measuring the actual voltage at the actuator motor and alternatively, for calculating the actuator motor voltage using digital processing techniques. A digital voltage command is then provided for applying compensated voltage to the actuator motor. Apparatus for implementing the methods of the invention in a hard drive assembly having an actuator motor is also described.

Abstract: An apparatus for providing sector location pulses to a controller of a rotating disk data storage device having a counter clocked in proportion to the disk rotation rate and an accumulator for accumulating times to sectors on the disk. A comparator connected to the counter and the accumulator enables an accumulator clock for repetitive clocking of the accumulator at such times the contents of the accumulator do not exceed the contents of the counter. A sector location pulse generator connected to the comparator generates the controller pulses, when enabled, concurrently with the accumulator clock signals. A master reset generator resets the first counter and the accumulator each time an index location on the disk passes a transducer head used to read and write data to and from the disk and a partial reset generator resets the accumulator each time the transducer head is moved between tracks on the disk.