error detection and correction

algorithm, storage (EDAC, or "error checking and

correction", ECC) A collection of methods to detect errors in

transmitted or stored data and to correct them. This is done

in many ways, all of them involving some form of coding. The

simplest form of error detection is a single added paritybit or a cyclic redundancy check. Multiple parity bits can

not only detect that an error has occurred, but also which

bits have been inverted, and should therefore be re-inverted

to restore the original data. The more extra bits are added,

the greater the chance that multiple errors will be detectable

and correctable.

Several codes can perform Single Error Correction, Double

Error Detection (SECDEC). One of the most commonly used is

the Hamming code.

At the other technological extreme, cuniform texts from about

1500 B.C. which recorded the dates when Venus was visible,

were examined on the basis of contained redundancies (the

dates of appearance and disappearance were suplemented by the

length of time of visibility) and "the worst data set ever

seen" by [Huber, Zurich] was corrected.

RAM which includes EDAC circuits is known as errorcorrecting memory (ECM).

[Wakerly, "Error Detecting Codes", North Holland 1978].

[Hamming, "Coding and Information Theory", 2nd Ed, Prentice

Hall 1986].

(1995-03-14)