US Patent 8140945 Hard component failure detection and correction

In one embodiment, a memory controller comprises a check bit encoder circuit coupled to receive a data block to be written to memory, a check/correct circuit coupled to receive an encoded data block read from the memory, and a hard failure detection circuit coupled to the check/correct circuit. The check bit encoder circuit is configured to generate a corresponding encoded data block comprising the data block, a first plurality of check bits, and a second plurality of check bits. The check/correct circuit is configured to detect an error in the encoded data block responsive to the first check bits, the second check bits, and the data block within the encoded data block, which is logically arranged as an array of R rows and N columns, wherein R and N are positive integers. Each of the first check bits covers a respective row of the array, and the check/correct circuit is configured to generate a first syndrome corresponding to the first plurality of check bits. A presence of more than one binary one in the first syndrome indicates a multi-bit error. Responsive to detecting the multi-bit error, the hard failure detection circuit is configured to perform a plurality of memory read/write operations to the memory locations in which the encoded data block is stored to identify a hard error failure in the memory.