Abstract: A technique for de-gaussing the pole tips and yoke of a write transducer in a perpendicular magnetic recording system is provided. An oscillator in the read channel is configured to produce an adjustable signal pattern output to the preamplifier when a write operation ends for a given time and at a predetermined frequency, such that as the preamplifier write current decays, it decays with transitions (polarity reversals). This results in a decaying AC field being applied to the write transducer at the end of a media write operation, effectively de-gaussing it and reducing the effects of remanent magnetization remaining in the poles and yoke of the magnetic recording head after a write current is turned off. This defeats a potential pole tip lockup or yoke lockup circumstance in the magnetic recording media which can result in an inability to write further data or a possible erasure of valid data on the hard disk with which the write head is associated.

Abstract: A disk drive clock circuit includes a servo clock generator and a disk locked frequency converter. The servo clock generator generates a servo clock signal in response to servo information read from a data storage disk in a disk drive. The disk locked frequency converter responds to the servo clock signal by generating a modified clock signal having a different frequency, and adjusts timing of an edge of the modified clock signal in response to a timing event identified from the servo information read from the disk. The disk locked frequency converter can include a divide-by-n counter that is configured to divide the frequency of the servo clock signal by a number n to generate the modified clock signal. The disk locked frequency converter can reset the divide-by-n counter to a defined value in response to the timing event. The modified clock signal can thereby be phase locked to the servo information on the disk.

Abstract: A disk drive includes a rotatable data storage disk, a head, a heater element, and a controller. The disk includes a plurality of data sectors between servo spokes. The head is configured to fly on an air cushion relative to the rotating disk while writing data on the data sectors. The heater element is attached to the head and configured to controllably heat the head responsive to a heater signal. The controller determines an upcoming pattern of selected ones of the data sectors on which data is to be written through the head in response to at least one write command from a host device, and controls the heater signal in response to the determined upcoming pattern of data sectors on which data is to be written.

Abstract: A disk drive includes a rotatable data storage disk, a transducer, an actuator, and a servo burst demodulator. The rotatable data storage disk includes a plurality of servo burst patterns thereon. The plurality of servo burst patterns are substantially radially aligned to each other, and radially adjacent ones of the servo burst patterns are configured to generate contributions to a read signal that are substantially orthogonal to each other. The transducer is configured to read the servo burst patterns on the disk to generate the read signal. The actuator is configured to position the transducer relative to the disk. The servo burst demodulator is configured to identify a separate contribution to the read signal from the radially adjacent servo burst patterns. The servo burst demodulator may be configured to generate transducer position information based on the identified separate contribution to the read signal from the radially adjacent servo burst patterns.

Abstract: Methods, circuits, and disk drive that correct errors in data that is temporarily stored in a memory buffer are disclosed. An error detection code and an error correction code are generated for data. The data, the error detection code, and the error correction code are stored in the memory buffer. The data is retrieved from the memory buffer and error detected using the error detection code. In response to detecting an error, the error correction code is applied to the retrieved data to generate corrected data.

Abstract: A disk drive includes a rotatable data storage disk, a head, a heater element, and a controller. The disk includes a plurality of data sectors between servo spokes. The head is configured to fly on an air cushion relative to the rotating disk while writing data on the data sectors. The heater element is attached to the head and configured to controllably heat the head responsive to a heater signal. The controller determines an upcoming pattern of selected ones of the data sectors on which data is to be written through the head in response to at least one write command from a host device, and controls the heater signal in response to the determined upcoming pattern of data sectors on which data is to be written.

Abstract: A method of and apparatus for handling errors occurring in data stored in memory is presented. Data to be stored in a buffer memory is applied to a generator matrix to generate parity check bits. The parity check bits are stored in the buffer memory along with the data. The stored data and parity check bits are read and the read data is used to regenerate the parity check bits. A result produced from the stored and regenerated parity check bits is usable to directly identify a location of an erroneous bit of the data in the buffer memory.

Abstract: An iterative decoder is controlled to iteratively decode a block by performing one or more decoding iterations for the block during a predetermined block time. The iterative decoder is further controlled to perform more decoding iterations for the block during a time in which the hardware of the iterative decoder is available, if the block fails to converge to correct data during the predetermined block time. The iterative decoder uses a parity-check matrix and can be configured to process that parity-check matrix for parallel, sequential or a combination of parallel and sequential (“hybrid”) parity constraint updates.

Abstract: A disk drive clock circuit includes a servo clock generator and a disk locked frequency converter. The servo clock generator generates a servo clock signal in response to servo information read from a data storage disk in a disk drive. The disk locked frequency converter responds to the servo clock signal by generating a modified clock signal having a different frequency, and adjusts timing of an edge of the modified clock signal in response to a timing event identified from the servo information read from the disk. The disk locked frequency converter can include a divide-by-n counter that is configured to divide the frequency of the servo clock signal by a number n to generate the modified clock signal. The disk locked frequency converter can reset the divide-by-n counter to a defined value in response to the timing event. The modified clock signal can thereby be phase locked to the servo information on the disk.

Abstract: Disk drive self-servo writing includes transferring a reference pattern by magnetic printing onto a reference disk, wherein the resulting printed reference pattern includes embedded servo information that provides servo timing and head position information, installing the reference disk and a head into the disk drive, reading the printed reference pattern using the head to generate a readback signal, sampling the readback signal at a sampling rate to generate a sampled signal, processing the sampled signal waveform spectrum to generate a recovered signal including the embedded servo information and fundamental and higher harmonics of the sampled signal, using the embedded servo information from the recovered signal to precisely position and maintain the head at concentric tracks of the reference disk, and self-writing servo patterns onto the tracks with the head.

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: A pointer-based modulation coding method and apparatus are presented. The pointer-based modulation coding operates to produce, from an unconstrained data stream of data blocks to be delivered to a data channel, a constrained data stream which satisfies a code constraint of the data channel. The pointer-based modulation coding replaces code constraint violating bit sequences occurring in each data block with values that form a linked list in such data block.

Abstract: A disk for a disk drive system includes a disk having a track format region including a spoke field region. The spoke field region has a single binary bit to identify angular position of a track with respect to disk head of the disk drive system.

Abstract: Sampling data with wide bi-phase code symbols includes sampling a wide bi-phase code symbol in the data a number (N) of times to produce samples of data, selecting a subset of the samples, determining which sample in the subset of samples has a largest magnitude, and selecting a subset of samples in a subsequent wide bi-phase code symbol based on a sample in a previous subset that has the largest magnitude.

Abstract: A non-volatile storage subsystem comprises a media I/O controller, a media access channel, and movable storage media. A non-volatile disk storage subsystem bas a read channel coupling a disk controller to a disk head assembly. A read channel interfacing subsystem is provided as part of the storage subsystem, and the read channel interfacing subsystem interfaces a disk controller to the read channel. The read channel interfacing subsystem comprises a set of process units and a pipeline manager.

Abstract: A method of storing data on a surface of a storage disk, the data being capable of verifying an identity of the surface, includes determining first check data from first alignment correction data associated with a first storage surface. The method also includes determining second check data from second alignment correction data associated with a second storage surface such that the second check data is different from the first check data if the first and second alignment correction data are identical. The method further includes writing the first and second check data to the first and second storage surfaces in association with the first and second alignment correction data, respectively.

Abstract: A disk for a disk drive system includes a disk having a track format region including a spoke field region. The spoke field region has a single binary bit to identify angular position of a track with respect to disk head of the disk drive system.

Abstract: A disk for a disk drive system includes a disk having a track format region including a spoke field region. The spoke field region has a single binary bit to identify angular position of a track with respect to disk head of the disk drive system.

Abstract: An apparatus includes a host port for coupling to a host. A storage disk is coupled to a disk port. A memory is provided for storing opcodes, data buffer pointers associated with the opcodes, and data in data buffers indicated by the data buffer pointers. A data transfer circuit is provided to store an address corresponding to a selected one of the opcodes. The data transfer circuit is responsive to a mode indicated by the selected opcode to transfer data between a selected data buffer associated with the selected opcode and one of the ports.

Abstract: A method of controlling a disk drive that reduces the space on the data storage surface of a storage disk otherwise effectively required to be taken up by embedded servo sectors. In disk drives employing wide-writer, narrow-reader, dual element heads, each servo burst field ends with a burst correction value (BCV) field. This BCV field enables the wide-writer head to be accurately positioned within track boundaries before writing begins to the data sector following a servo sector. The present invention takes advantage of the fact that burst correction values are only required by the head incident to data writing operations. Since a finite settle time is required to switch the read channel from servo mode to user data mode, and since the BCV field is not needed for reading operations, mode switching and channel settling can begin while the head is still passing over the BCV field.