Memory system that provides guaranteed component-failure correction with double-error correction

Abstract

A memory system accesses a block of data, each block including bits logically divided into rows and columns, each column including a row-checkbit column, an inner-checkbit column, and data-bit columns. Each column is stored in a different memory component, and checkbits are generated from databits to provide block-level correction for a failed memory component, and double-error correction for errors in different memory components. The system calculates a row syndrome and an inner syndrome for the block of data, the inner syndrome resulting from any two-bit error in the same row being unique. The system can use the row and inner syndromes to determine whether errors are associated with a failed memory component. If not, the system can use the row and inner syndromes, and inner syndromes for all possible combinations of one-bit errors occurring in two rows with a row syndrome of one to correct two bits.