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公开(公告)号：DE3779553T2
公开(公告)日：1993-01-28
申请号：DE3779553
申请日：1987-09-08
Applicant: IBM
Inventor： PATEL ARVIND MOTIBHAI , WANG DAVID TAR-WEI , YU WELLINGTON CHIA-PEIR
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.
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公开(公告)号：DE3750380T2
公开(公告)日：1995-03-30
申请号：DE3750380
申请日：1987-05-05
Applicant: IBM
Inventor： NG CHAN YIU , OUCHI NORMAN KEN , WANG DAVID TAR-WEI , YU WELLINGTON CHIA-PEIR
Abstract: A record that emulates a first recording format, which includes a track reference point, such as an index field, used for determining a position of a record on a track according to the first recording format, is recorded on a moving storage device operating according to a second recording format which also includes a track reference point by the following method. The method comprises the steps, responsive to location information generated according to the first recording format, of: (1) determining an original angular position of a record according to the first recording format; (2) calculating in response to the original angular position and a parameter a preferred angular position for the record according to the second recording format; (3) determining an actual angular position of the record recorded according to the second recording format; and (4) recording an extension of the record to compensate for the difference between the preferred angular position and the actual angular position. h
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公开(公告)号：DE3750380D1
公开(公告)日：1994-09-22
申请号：DE3750380
申请日：1987-05-05
Applicant: IBM
Inventor： NG CHAN YIU , OUCHI NORMAN KEN , WANG DAVID TAR-WEI , YU WELLINGTON CHIA-PEIR
Abstract: A record that emulates a first recording format, which includes a track reference point, such as an index field, used for determining a position of a record on a track according to the first recording format, is recorded on a moving storage device operating according to a second recording format which also includes a track reference point by the following method. The method comprises the steps, responsive to location information generated according to the first recording format, of: (1) determining an original angular position of a record according to the first recording format; (2) calculating in response to the original angular position and a parameter a preferred angular position for the record according to the second recording format; (3) determining an actual angular position of the record recorded according to the second recording format; and (4) recording an extension of the record to compensate for the difference between the preferred angular position and the actual angular position. h
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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
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.
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