ECC memory

(Error-Correcting Code memory) A memory system that tests for and corrects errors automatically, very often without the operating system being aware of it, let alone the user. As data are written into memory, ECC circuitry generates checksums from the binary sequences in the bytes and stores them in an additional seven bits of memory for 32-bit data paths or eight bits for 64-bit paths. When data are retrieved from memory, the checksum is recomputed to determine if any of the data bits have been corrupted. Such systems can typically detect and automatically correct errors of one bit per word and can detect, but not correct, errors greater than one bit. See EOS memory, chipkill, checksum and parity checking.

    Memory Type    Detects       Corrects
    Non-parity     0             0
    Parity         1 bit         0
    ECC            1 or 2 bits   1 bit