SECDEDkoodeja

SECDEDkoodeja, known in English as SECDED codes, stand for Single Error Correct, Double Error Detect. They are a class of error-correcting codes designed to protect data against bit flips by extending a standard Hamming code with an additional parity bit. The result is an extended Hamming code that can correct any single-bit error and detect double-bit errors.

How they work is based on parity checks. A data word is encoded with several parity bits that form a Hamming code, and an extra overall parity bit is added to the codeword. During decoding, a syndrome is computed from the Hamming parity bits to indicate the position of a potential single-bit error. If the overall parity bit also indicates an error, the system can correct that single-bit error. If a double-bit error occurs, the overall parity check signals that an error has happened, but the code cannot reliably determine a correct bit to flip, so the error is detected but not corrected. In practice, SECDED provides protection that improves reliability by enabling error correction for single-bit faults and error detection for more complex faults.

Applications of SECDED codes are common in computer memory and data storage. They are widely used in ECC (error-correcting code) memory to protect data paths in RAM, often using a word size with seven Hamming parity bits plus one overall parity bit, resulting in a codeword longer than the data word (for example, 64 data bits with 8 ECC bits in many systems). This approach enhances data integrity in servers, workstations, and other systems where reliability is critical.