Communications: electrical – Digital comparator systems
Patent
1975-05-06
1976-12-14
Thesz, Joseph M.
Communications: electrical
Digital comparator systems
360 27, 360 50, G06F 722, G06F 1100
Patent
active
039978761
ABSTRACT:
Apparatus and a method for controlling the reading and writing operation of a peripheral storage system such that a magnetic recording medium, having small defective areas in the magnetic surface at which data cannot be reliably recorded may be used. Each data track on the magnetic recording medium has a reserve capacity which is used as a special gap. The recording medium is initialized such that the distance from a point of origin to a surface defect in each track is recorded in a header area in each track. The apparatus and method herein described cooperate with this initialized magnetic recording medium so as to control the format of data recorded onto the magnetic recording medium such that any defect in the recording medium will not affect a reading or writing operation of the storage system. The apparatus and method will cause the distance between a reference point in each record to the defect within the track at which the record is being recorded to be recorded in a control field at the beginning of that record. The apparatus and method monitors the distance recorded in descending terms within the records recorded on a given data track such that during a write operation the write sequence is altered so that the special gap will approximately be centered over the defect if the defect is to affect information recorded in that record. During a read operation, if the surface defect is to affect the record being read, the system will recognize the special gap which has been recorded over the defect and accept that information as non-data information, therefore, making the system transparent to the defect. Effectively, the apparatus and method allow the movement of the special gap to any position within the data track such that a defect may be made transparent to the operating storage system.
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Brodie R. Bruce
International Business Machines - Corporation
Thesz Joseph M.
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