Abstract: A system and method for accessing data stored on surfaces of discs in a disc drive utilizing more than one serpent per recording zone. The serpents are traversed using a defect descriptor table and one or more physical zone tables (PZTs). An Address Translation Logic Unit is configurable to use one or more PZTs to access multiple serpents per recording zone.

Abstract: A method and apparatus for an error-correction buffer having self-throttling data burst control in a disc drive. One aspect of the present invention provides an arbitration-throttling control circuit for use in a disc drive to self-throttle the data transfer of an error-correction buffer. The arbitration-throttling control circuit includes a control circuit having an error-correction buffer interface and a disc-drive main buffer memory interface for controlling data transfer from the error-correction buffer to a disc-drive main buffer in a plurality of data bursts. The control circuit arbitrates for access to transfer data into the disc-drive main buffer such that a series of data bursts from the error-correction buffer to the disc-drive main buffer are spread substantially evenly over a period of time.

Abstract: A system and method for accessing data stored on surfaces of discs in a disc drive utilizing more than one serpent per recording zone. The serpents are traversed using a defect descriptor table and one or more physical zone tables (PZTs). An Address Translation Logic Unit is configurable to use one or more PZTs to access multiple serpents per recording zone.

Abstract: A memory medium has a plurality of tracks arranged in a plurality of sectors with each track sector having a format which does not include header fields identifying sectors or sector defects or defect management procedures. Track management apparatus identifies the track sector currently confronting a transducer; the track management being based on sector pulses (in the case of a dedicated servo system), or being calculated based on track information, an index pulse and data wedge information from previous wedges (in the case of embedded servo systems), or being derived from a lookup table. To accommodate sector defects, a defect bank contains the identity and type of each defective or spare sector.

Abstract: An apparatus and method are disclosed for recovering from a header error condition in a disc drive of the type having a rotatable disc having a plurality of concentric tracks with data fields for the storage and retrieval of data and header fields providing logical address information for the data fields. The header fields include read and write header fields which are used during read and write operations, respectively, to align read and write elements of the head with the data fields. When the disc drive unsuccessfully decodes the logical address information from a selected header field associated with a selected data block, an alternate header error recovery routine is performed wherein attempts are made to decode the logical address information from the alternate header field associated with the selected data block. Radial offsets can further be applied to the head to enhance the decoding of the logical address information from the alternate header field.

Abstract: An apparatus and method for recovering from read errors detected by a read channel (70) in a sequence of data read from a disc (18) of a disc drive (10) by using read channel quality indicators to determine the appropriateness of using error correction in combination with other corrective actions utilized in the recovery process. Upon the detection of an uncorrected error in the retrieved data, the disc drive (10) enters a read error recovery routine wherein one or more corrective actions (102, 122) are applied in an effort to resolve the error. One of the channel quality indicators comprises a channel quality measurement (108, 128) determined as the sum of the square of the sampled data bit error values recovered during the read operation.

Abstract: A memory medium has a plurality of tracks arranged in a plurality of sectors with each track sector having a format which does not include header fields identifying sectors or sector defects or defect management procedures. Track management apparatus identifies the track sector currently confronting a transducer; the track management being based on sector pulses (in the case of a dedicated servo system), or being calculated based on track information, an index pulse and data wedge information from previous wedges (in the case of embedded servo systems), or being derived from a lookup table. To accommodate sector defects, a defect bank contains the identity and type of each defective or spare sector.

Abstract: A data transfer circuit for coordinating transfer of data between a host and a disc of a disc drive having a state machine for coordinating with a buffer controller to transfer data between the host and a buffer segment and a second state machine for coordinating with the buffer controller to transfer data between the buffer segment and a disc of the disc drive. Counting circuits count the number of bytes transferred between the host and the buffer segment and between the buffer segment and the disc and provide sector count signals each time a sector of data is transferred into or out of the buffer segment. The sector count signals are received by a buffer manager which includes counters for counting sectors of data transferred into and out of the buffer segment and a comparator circuit that compares the contents of the buffer manager counters to provide a code indicative of the state of the buffer segment to a decoder.