Abstract: Embodiments of the present invention efficiently format long sectors, without decreasing the performance, in a magnetic disk drive in which servo sectors are radially formed at regular intervals, and make full use of the ECC performance that is enhanced by the long sectors. In one embodiment, a data format in each zone on a magnetic disk is completed by a plurality of tracks N (N is an integer, which is 2 or more). The storage capacity per track of the outermost radius zone Z#1 is 150 kB. In this zone, long sectors each having a length of 32 kB are formatted with the number of tracks per format N#1=3. The storage capacity per track of the innermost radius zone Z#m is 80 kB. In this zone, long sectors each having a length of 32 kB are formatted with the number of tracks per format N#m=2.

Abstract: A determining unit determines whether a clock signal is oscillated with an oscillation amplitude equal to or greater than a predetermined value. An output control unit outputs the clock signal to an output destination when the determining unit determines that the clock signal is oscillated with the oscillation amplitude equal to or greater than the predetermined value.

Abstract: A method for preventing electrical overstress from interfering with a magnetic read-write device by identifying one or more characteristic functions of the device that characterize electrical overstress, generating a wave form representative of the electrical overstress by using the one or more characteristic functions and enabling the generated wave form to be combined with a read signal to counteract the electrical overstress. The method can be implemented with a crosstalk cancellation circuit that includes a coupler filter configured to receive signals from the write driver, a differentiator to differentiate the signal, a gain adjust coupled to the coupler filter configured to adjust gain on the received signal, a phase adjust configured to adjust the phase to match the crosstalk, and an inverter coupled to invert the matched signal to enable cancellation of the crosstalk.

Abstract: A disk drive has multiple disk surfaces and corresponding heads, each disk surface includes multiple regions, and each head is for recording on and playback of information from a corresponding disk surface. The data track density in a first region on a first disk surface is different than the data track density in a second region on a second disk surface, and the first and second regions are radially similarly situated regions. A method of sequentially accessing data in the first and second regions includes sequentially accessing data tracks in the first region and then sequentially accessing data tracks in the second region.

Abstract: Provided is a read channel incorporated in a storage device to process signals read from a storage medium. The read channel includes an equalizer equalizing input read signals to produce equalizer output signals. A detector senses an adjusted equalizer output signal to determine an output value comprising data represented by the input read signals. An equalizer adaptor receives the output value from the detector to determine a first error signal used to adjust the equalizer operations. A component adjusts the equalizer output signals being transmitted to the detector, wherein the component is adjusted by a second error signal calculated from the output value from the detector, wherein the first and second error signals are different.

Abstract: Embodiments of the invention provide a magnetic disk drive capable of reducing an area used for a preamble of each data sector to increase the storage capacity. The magnetic disk drive adopts a data-surface servo system. In one embodiment, main preambles are written on a magnetic disk at a frequency of a data clock. Each of data sectors is written with a write clock that is synchronized with a signal obtained by reading the main preamble. The data sectors include sub preambles respectively. When the data sector which has been written in this manner is read, a read clock is synchronized by use of a signal obtained by reading the main preamble, and a signal obtained by reading the sub preamble included in a data sector to be read. The bit length of the sub preamble is shorter than that of the conventional preamble that is used to independently achieve the synchronization.

Abstract: A recording system, such as a magnetic or optical recording system, employs optimization metrics that are independent of a target partial response for equalization of a signal read from a recording channel. The optimization metrics employ samples adjacent to codeword boundaries of codewords representing encoded data, such as servo data, read from a recording medium. The optimization metrics are used to select filter parameters and/or tap weights for equalization. The filter parameters and/or tap weights might be derived based on the type of data read from the recording medium, the type of detector employed to detect the codewords of the read data, and the type of encoder/decoder employed for the read data.

Abstract: Fast data patterns with desired edge positions are provided. A pattern generator (PG) circuit 10 stores and provides data patterns and respective position control data. A delay circuit 16 delays a clock CLK to produce a position control clock according to the position control data. An output flip flop 18 provides the data patterns following to the position control clock. The position of the clock is controlled as an operation reference of the data pattern and, as a result, controls the edge positions of the output data pattern.

Abstract: In a perpendicular magnetic recording system, the data that is being written by the write channel is fed back into the read channel. The read channel processes the data and decides if the written sequence is likely to have very poor DC characteristics. If that is the case, the write channel changes a scrambler seed and rewrites the data using the new scrambler seed. The data may also be inspected for patterns that might cause large baseline wander before being written to disk, i.e., in the write channel. A data sequence may be repeatedly scrambled and encoded until an acceptable level of estimated DC-wander has been achieved. The data sequence may then be written to disk.

Abstract: A phase interpolator is provided that, in one implementation, includes an output node, a plurality of phase input circuits, and a plurality of switches corresponding to the plurality of phase input circuits. Each phase input circuit is operable to receive a given phase signal. Each switch is in communication with a given phase input circuit and is operable to couple a given phase signal to the output node.

Abstract: A method of determining frequency bands of a data storage system and an apparatus using the same are provided. More particularly, a method of determining frequencies used for reading and writing data from and to a disk drive while avoiding frequencies that have adverse effects on a system and a disk drive using the same are provided. A method of determining read and write frequencies of the data storage system may include determining frequencies that have adverse effects on functions of the data storage system; selecting frequencies to be used when reading and writing data to and from a disk drive while avoiding the frequencies determined to have adverse effects on the functions of the data storage system.

Abstract: Embodiments of the invention provide a servo information write method that makes it possible to properly locate the last-written servo information even when old servo information is overwritten by new servo information. In one embodiment, a servo track writer controller, which is within a servo track writer, reads a serial number (S/N) from a HDD (step 101), and acquires a magnetic disk drive servo information write count (P-ID) from a manufacturing process host (step 102). The next step (step 103) is then performed to control a positioner and a read/write channel so as to start writing servo information onto a magnetic disk. Servo information is sequentially written until the last track is written into (step 104). When the Nth servo information is to be written, a P-ID (N) is written subsequently to a burst signal (step 105). When the last track is written into in step 104, step 106 is performed to notify the manufacturing process host that the Nth servo information write is performed.

Abstract: Magnetic tape read channel signal values are developed employing intermediate bits of the path memory of a PRML Viterbi detector. Identification logic identifies a most likely path memory state of the PRML Viterbi detector from the path metrics of the PRML Viterbi detector. An intermediate bit sequence of the identified most likely path memory state is obtained, the intermediate bit sequence extending from an initiation point of the path memory which is intermediate the output and the input of the PRML Viterbi detector. A sample value is determined which corresponds to the obtained intermediate bit sequence.

Abstract: Data reliability testing for a magnetic tape drive is conducted separately for the channels of a magnetic tape drive which write and read tracks of a multiple track magnetic tape. Memory stores testing data representing data separately written to tracks of a multiple track magnetic tape; each of a plurality of read channels reads data sensed by a tape head from a separate track of a magnetic tape; and error processing logic detects differences between data from each of a plurality of the read channels, and stored testing data of the memory representing data written to the same separate tracks.

Abstract: Embodiments of the invention provide a magnetic disk drive and its control method capable of effectively using the unrecordable area which is caused due to the composite magnetic head's gap between the read head and the write head. In one embodiment, a disk drive comprises a composite magnetic head structured in such a manner that during write the write head WH reaches each servo area earlier than the read head RH, and a read write control unit to control the write and read done by the composite magnetic head. On the disk, common servo data SP to be used both during read and during write, write servo data SW to be used during write and read servo data SR to be used during read are recorded in this order in each servo area. During write, the read write control unit starts the write head recording data at the timing when reading write servo data SW from the servo area is completed.

Abstract: An apparatus and method for improving the error rate of track information on a magnetic storage device is disclosed. One embodiment provides a counter for counting the number of writes to a first track on a magnetic storage device. In addition, a re-read and re-write initiator is provided for reading information from a second track adjacent to the first track and re-writing the information read from the second track back to said magnetic storage device when said counter reaches a pre-defined number of writes for the fist track.

Abstract: A method for identifying adjacent track interference for a head is provided. The method comprises writing a first data track at a predetermined track position; writing a second data track two track positions away from the first data track; and validating the position of the first data track and the second data track. Upon validation the method further comprises writing a third data track between the first data track and the second data track and analyzing a signal profile of at least one of the first data track and the second data track for adjacent track interference.

Abstract: An amplifying circuit and method are disclosed for amplifying electrical signals, such as electrical signals generated by the read head of a disk drive. The circuit includes a pair of cross-coupled differential amplifier circuits. Each differential amplifier circuit is asymmetric, including two input transistors of different transistor types. For instance, a first of the two input transistors of each differential amplifier circuit may be a bipolar transistor and a second of the two input transistors may be a field effect transistor. By utilizing asymmetric differential amplifier circuits, a relatively wider operating frequency range is obtained.

Abstract: A synchronization system includes a signal generating module that generates a signal comprising modulated waveforms and a timing window generator that generates a timing window. A proportional integral controller (a) divides the timing window into a first half window and a second half window, (b) demodulates the digital signal in the first half window and the second half window, (c) compares an amplitude of demodulated signal in the first half window to an amplitude of demodulated signal in the second half window, (d) calculates a new location for the timing window, and (e) repeats (b), (c), and (d) until the amplitude in the first half window equals the amplitude in the second half window.

Abstract: A write head for a magnetic storage system energizes a write coil for a plurality of bit intervals and selectively shutters the magnetic field to alter a magnetic domain of a magnetic storage medium for each bit interval. The position of the shutter may be controlled using a micro-electro mechanical system. Magnetic pole segments provide a loop between the write coil and the magnetic storage medium. Magnetic shielding on the shutter mechanisms controls the reflection of the magnetic fields. In a rewritable magnetic storage system, a first write coil generates a positive magnetic field and a second write coil generates a negative magnetic field. A shutter is associated with each write coil to selectively allow the positive or negative magnetic fields to alter the magnetic domain of the magnetic storage medium. The positive or negative magnetic fields can alter the magnetic domain in a collocated region of the magnetic storage medium to avoid jitter.