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Technique for Improved Recovery From Double Hard Errors Plus a Single Soft Error Disclosure Number: IPCOM000064840D
Original Publication Date: 1985-Sep-01
Included in the Prior Art Database: 2005-Feb-19

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Ryan, PM [+details]


All double errors due to two stuck faults or one stuck fault and one soft fault are recovered from by means of complement/recomplement (C/RC). C/RC fails against two stuck faults plus a soft fault, when one of the stuck faults is hidden (stuck in the same sense as correct data). This article describes a procedure implementable in logic, microcode, or software by which some, but not all, of such errors may be recovered from. Two stuck faults in an ECC (error correcting code) word are always recoverable by single error correct/double error detect (SEC/DED) correction codes or by complement/recomplement methods. When two stuck faults are joined by a soft fault, the type of SEC/DED plus C/RC now envisioned for large systems begins to break down. Fig. 1 shows what happens.