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    System and method for correcting errors in coded data recorded in blocks and sub-blocks
    2.
    发明专利
    System and method for correcting errors in coded data recorded in blocks and sub-blocks 未知

    公开(公告)号：HK138794A

    公开(公告)日：1994-12-16

    申请号：HK138794

    申请日：1994-12-08

    Applicant: IBM

    Inventor： PATEL ARVIND MOTIBHAI

    IPC: G06F11/10 ,  G06F12/16 ,  G11B20/18 ,  H03M13/29 ,  H03M13/00

    Abstract: The present invention relates to an error correcting system for correcting errors in coded data recorded on a record medium in blocks of data bytes, in which each block comprises at least one sub-block, of data bytes and at least one sub-block error check byte (C1 to C3) and at least one block error check byte. The system is of the type which comprises error syndrome byte generating means, responsive to the error check bytes recorded in each sub-block, for generating, during read out of the data bytes and error check bytes in each sub-block, error syndrome bytes, and error correcting means, responsive to the error syndrome bytes, for correcting errors in the data bytes read out from each of the sub-blocks. … A system according to the invention is characterised in that it comprises… first error syndrome byte generating means for generating sub-block error syndrome bytes, corresponding to the check bytes associated with each sub-block,… first error syndrome processing circuitry (73), responsive to the sub-block error syndrome bytes, to detect and correct a predetermined number of errors in the data bytes in each sub-block and to detect but not correct another predetermined number of errors in the data bytes in each sub-block,… additional block error check byte generating means (72B) for generating additional block error check bytes (C0) for each block, corresponding to uncorrected errors in any sub-block in each block,… second error syndrome byte generating means for generating additional block error syndrome bytes, corresponding to the error check bytes in each block and the additional block error check bytes, and… second error syndrome processing circuitry (74 - 78), responsive to the block error syndrome bytes, to correct additional errors in the data bytes in each block.

    4.
    发明专利
    未知

    公开(公告)号：DE3779553D1

    公开(公告)日：1992-07-09

    申请号：DE3779553

    申请日：1987-09-08

    Applicant: IBM

    Inventor： PATEL ARVIND MOTIBHAI ,  WANG DAVID TAR-WEI ,  YU WELLINGTON CHIA-PEIR

    IPC: G06F3/06 ,  G06F11/10 ,  G11B20/10 ,  G11B20/18 ,  H03M13/00 ,  H03M13/03 ,  G11B20/12

    Abstract: In a data processing system in which two-level error correction is performed on variable length data being transferred between the host processor and the data storage device, the logical length of the data being transferred is computed during a fixed time gap with computation continuing after termination of the fixed time gap and commencement of the data transfer. The computation required for the logical length of the data field to accommodate two-level ECC is accomplished by first comparing the actual field length with a value predetermined by the subblock length of the two-level ECC. If the actual length is greater than the predetermined value, then a value equal to the subblock length plus first level ECC bytes is loaded into a counter which begins decrementing at the termination of the fixed time gap so as to synchronise the byte-by-byte transfer of the data. As the data is being transferred the computation continues. When the computation has been completed, a value equal to the difference between the computed logical length and the subblock length plus first level ECC bytes is loaded into other counters which begin decrementing when the first counter reaches zero. In this manner transfer of the data is not interrupted. This permits two-level ECC to be incorporated into prior data processing systems which utilise a conventional track format with predetermined fixed time gaps, even though such fixed time gaps would otherwise be of insufficient duration to permit computation of the logical length required for two-level ECC.

    5.
    发明专利
    未知

    公开(公告)号：BR8904735A

    公开(公告)日：1990-05-01

    申请号：BR8904735

    申请日：1989-09-20

    Applicant: IBM

    Inventor： EGGENBERGER JOHN SCOTT ,  HODGES PAUL ,  PATEL ARVIND MOTIBHAI

    IPC: G06F11/10 ,  G11B20/18 ,  H03M13/00

    Abstract: A method is disclosed for correcting multibyte errors in a magnetic medium on which data is recorded in variable length blocks that comprise sub-blocks of data bytes and corresponding check bytes and include error correction code (ECC) for which ECC syndromes are generated during reading. A sequence of N sequential parity check bytes is written at the end of each block. After ECC syndromes are generated during reading, parity syndromes are generated by comparing parity check bytes computed from data bytes and check bytes as read with the parity check bytes as written. When a long-burst error occurs, a pointer points to the first of the N consecutive bytes in a block that could have been influenced by the error burst. After correcting correctable errors in all sub-blocks not affected by the N bytes identified by the pointer, and adjusting the parity syndromes for errors thus corrected, the adjusted parity syndromes are used to correct the errors in the N bytes indicated by the pointer. Unused ECC syndromes are then adjusted for errors corrected by the adjusted parity syndromes and used to correct all correctable errors then remaining.

    MULTIBYTE ERROR CORRECTION
    7.
    发明专利
    MULTIBYTE ERROR CORRECTION 未知

    公开(公告)号：AU560216B2

    公开(公告)日：1987-04-02

    申请号：AU2467084

    申请日：1984-02-16

    Applicant: IBM

    Inventor： PATEL ARVIND MOTIBHAI

    IPC: G06F11/10 ,  G11B20/18 ,  H03M13/00 ,  H03M13/15 ,  G06F11/08

    Abstract: A two-level multibyte error correcting system for correcting up to t, one-byte errors in a codeword in response to processing 2t, non-zero syndrome bytes at the first level and up to t 2 one-byte errors in a codeword in response to processing 2t 2 non-zero syndrome bytes at the second level when processing said 2t, syndrome bytes at said first level does not produce an all zero pattern for said 2t 2 syndrome bytes. The system is particularly applicable to data handling devices such as disk files, where in a relatively long block of data may be divided into subblocks, each of which may contain up to t, - x one-byte errors that are correctable at the first level by processing 2t, non-zero syndrome bytes. One identifiable subblock of the word may contain up to t, + x one-byte errors which are correctable by processing said 2t 2 non-zero syndrome bytes where 0 ≤ x 2 - t 1 ).

    10.
    发明专利
    未知

    公开(公告)号：DE69030073D1

    公开(公告)日：1997-04-10

    申请号：DE69030073

    申请日：1990-12-17

    Applicant: IBM

    Inventor： PATEL ARVIND MOTIBHAI ,  SO BUM SUCK ,  RUTLEDGE ROBERT ANTHONY

    IPC: G11B20/18 ,  G11B5/09 ,  G11B20/10 ,  G11B20/14 ,  H04L25/49 ,  H03M5/14

    Abstract: A method is disclosed for processing, in a signal processing channel, digital values corresponding to a digitized incoming analog signal representative of coded binary data. A state-dependent sequence detection algorithm includes two groups of appropriate functional expressions of digital sample values, which expressions are identical but offset one sample position from each other. During each iterating step with successive pairs of clock cycles, the value of each expression in the said two groups of expressions is precomputed from a preselected number of sample values ahead of a then current sample value; preselected ones of these expression values are compared against an appropriate threshold, which is the same for corresponding expressions of each group, to provide respective binary decision outputs corresponding to each of the two groups; and the current state value then advances to two next successive state values. During precomputation, a preselected greater number of sample values ahead of the current sample is preferably used in a pipelined configuration to allow additional time for precomputing said groups of expressions.

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