Seagate Technology Incorporated

Hieu Van Nguyen

Ara Patapoutian

Prafulla Bollampalli Reddy

Housan Dakroub

John Stuart Wright

Hui Su

Clyde Everett Goodner, Iii

Michelle Elaine Blankenship

Eddie Wai Pun

Robert D Cronch

Karl Louis Enarson

John M Baker

Mark David Hertz

Deanne Sue Grover

Presented is a data channel with selectable components, such as encoders or decoders. Also, data having different data signal characteristics can be processed through a data channel based on the data signal characteristics. Further, a data channel may have independent encoding path and an independent decoding path. For example, a first data transmission having first data signal characteristics may be processed via a data channel based on a first selected set of components of the data channel and a second data transmission having second data signal characteristics different than the first data signal characteristics may be processed via the data channel using a second selected set of components in the data channel. The first selected set of components may be different than the second selected set of components, but may share one or more common components.

Multiuse data channel

An implementation of a system disclosed herein provides a method of deferring decoding of a data sector received at a read channel of a storage device, in response to determining that a data sector cannot be decoded by a first decoder and storing the data sector for further processing by a second decoder.

Read channel throughput management

Devices and/or methods for managing a buffer containing failed data may utilize side information related to the failed data. The side information may include, e.g., a decoding-success score representing an estimated amount of errors and/or a local host requested status for buffered or unbuffered failed data.

Buffer management using side information

Devices and/or methods may decode failed data, e.g., utilizing side information related to the failed data to determine how to decode the failed data. The side information may include, e.g., a decoding-success score representing an estimated amount of errors within a failed data portion, a remaining amount of unread portions of a data block including failed data, an amount of requested portions of a data block including failed data, if the failed data is buffered, and a decoding status of any previously-failed data.

Data decoding using side information

Apparatus in a disc drive for transferring data between a rotatable disc and a host computer. An analog pre-processor integrated circuit device incorporates circuitry to carry out analog processing functions including write current driving, readback signal amplification, prewrite compensation, frequency-domain filtering, and equalization. A digital post-processor integrated circuit device incorporates circuitry to carry out digital signal processing functions including Viterbi detection, decoding, error detection and correction, buffering, host interface functions, and data encoding and serialization. The analog pre-processor is preferably mounted within the interior environment of the disc drive to an actuator assembly that supports a head adjacent the disc. The digital post-processor is preferably supported on a printed circuit board mounted to an exterior surface of the disc drive.

Partitioning disc drive read/write electronics to improve data transfer performance

Apparatus and method for improving operational performance of a disc drive by detecting defective servo burst patterns. A rotatable disc is provided with servo data which include a plurality of servo burst patterns to define a plurality of tracks. A head transduces the burst patterns to provide burst signals to a servo circuit which controllably positions the head with respect to the surface of the disc by determining a position error signal from a combination of the burst signals. The servo circuit identifies a selected servo burst pattern as defective in relation to differences between absolute values of successive pairs of peak amplitude samples from the burst signal.

Servo burst pattern defect detection

An apparatus and method are disclosed for minimizing damage to a disc drive during head switching operations. The disc drive comprises a plurality of magnetic recording surfaces to and from which data are transferred using read/write heads, each head utilizing the application of a bias current during operation. To switch from a presently selected head to a target head, the disc drive determines a first value indicative of the magnitude of a bias current for the presently selected head and a target bias current to be applied to the target head. When the second value is greater than the first value, the disc drive switches from the presently selected head to the target head and then applies the target bias current; conversely, when the first value is greater than the second value, the target bias current is applied to the presently selected head and then the disc drive switches from the presently selected head to the target head.

Head switching sequence in a disc drive employing head bias currents

A method of measuring the read-to-write offset of a track in a disc drive system having separate read and write elements by measuring read error rate as a function of incremental actuator offset. The actuator is incrementally moved from one edge of the track to the other. The two radial positions which produce read error rates within acceptable limits are identified, and the read-to-write offset is determined by subtracting the offset at which the track was written, from the midpoint of the two radial positions. The read-to-write offset for each track accessed by the transducer is calculated from the read-to-write offset measured at the track.

Method of measuring the read-to-write offset in a disc drive having separate read and write elements

Apparatus and method for simultaneously biasing multiple magneto-resistive read elements in a disc drive head/disc assembly. A preamplifier circuit sequentially applies read bias currents to successive pairs of heads of the head/disc assembly, wherein the read bias current applied to a selected one of each pair of the heads is used to transduce the servo data from the associated disc recording surface, and the read bias current applied to the remaining one of each pair of the heads is used to prepare the remaining one of each pair of the heads to subsequently transduce the servo data from the associated disc recording surface. The preamplifier circuit includes at least first and second read bias current sources and a head selection circuit.

Simultaneously biasing multiple magneto-resistive read elements

Apparatus for improving data writing operations to a disc recording surface of a disc drive. A head assembly is supported over the disc recording surface by a flexible suspension assembly of a controllably positionable actuator assembly and includes a write current shaping circuit integrated with a write element. The write current shaping circuit modifies write currents received by the head assembly via a transmission line from a preamplifier driver circuit to remove undesired characteristics from the received write currents. The write element writes data to the disc recording surface using the write currents as modified by the write current shaping circuit.

Head assembly with integrated write current shaping circuit

Apparatus and method for servo writing with simultaneous biasing of multiple magneto-resistive read elements in a disc drive head/disc assembly. A preamplifier circuit sequentially applies read bias currents to successive pairs of heads of the head/disc assembly, wherein the read bias current applied to a selected one of each pair of the heads is used to transduce the servo data from the associated disc recording surface, and the read bias current applied to the remaining one of each pair of the heads is used to prepare the remaining one of each pair of the heads to subsequently transduce the servo data from the associated disc recording surface. The preamplifier circuit includes at least first and second read bias current sources and a head selection circuit.

Servo writing with simultaneous biasing of magneto-resistive read elements

An apparatus and method for performing real-time, closed loop write verification in a disc drive having a rotatable magnetic disc and a head having read and write elements. During a write operation, the disc drive generates a write current signal indicative of input data to be written to the disc. The write current signal is applied to the write element, which generates a time-varying magnetic field to simultaneously induce a readback signal in the read element through magnetic coupling of the read element to the write element, and to magnetize the disc to write the input data to the disc. The readback signal induced in the read element is used to reconstruct a set of output data which is used to verify accuracy of the input data.

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Oklahoma City, OK, United States of America

Hieu Van Nguyen