High performance fault tolerant memory system utilizing greater than four-bit data word memory arrays

Abstract

A method for providing a fault tolerant memory system having a number of memory arrays that includes at least one spare memory array and utilizing a data word organization of greater than 4 bits. The method includes detecting a multi-bit word error in a memory array. In an advantageous embodiment, a single package detect (SPD) logic, for detecting a package error of 1-4 bits, is utilized to identify the failed memory array. Next, the content of a first row of cells in the failed memory array is read and a first complement of the content is generated. Subsequently, the first complement is written back to the first row of cells in the failed array. A second read operation is then initiated to retrieve the first complement from the failed memory array, following which, a second complement of the first complement is generated. The second complement is then written to a corresponding first row of cells in the spare memory array and the method is repeated for all row of cells in the failed memory array. The method further includes replacing the failed memory array with the spare memory array for future READ/WRITE operations by comparing the address of the failed memory array with a memory array address of a READ/WRITE operation and directing the READ/WRITE operation to the spare memory array in the event that the addresses are equal.