Memory system restructured by deterministic permutation algorithm

摘要

Swapping of physical bits between different logical words of a memory (40) is accomplished by reference to data (46) on bad bits in the memory. Different permutation data (34) are selected to control address inputs to each bit position (12i) in a memory word so that any word with multiple uncorrectable data is changed to a correctable logical data word by placing one or more of the bad bits in the original word into another word of the memory. The swapping is done by an exclusionary process (48) which identifies and deselects certain deleterious potential combinations of actual addresses thereby limiting the selection process to ohter combinations. The process can involve categorizing (44) of failures in accordance with type, and performing (48) algorithm operations which identify combinations of bit addresses that would result in combining the failures so that there are more errors in any memory word than would be correctable by the error correction code monitoring (42) the memory.