The spread-out the defect correction with individual - - packet error correction and double - package - error detection codes.

摘要

A digital error detection and correction apparatus for correcting n-bit data words comprising a field of n-r data bits and a field of r error-correcting-code-ECC bits according to an error correcting code. The n-bit data words are organized in packages of b bits, and the invention is capable of correcting one package having suffered at least one hard failure and a single soft error being located in a different package. The apparatus of the invention involves an error correcting code which gives a first syndrome when the data word has suffered a first error coming from at least one error in a first package and a single error in a second package different from the first package, which also gives a second syndrôme when the data word has suffered a second error coming from at least one error in the above first package, and a single error in a third package. The error correcting code is such that the equality of the above first and second syndromes results in the equality of the first and second errors. The apparatus of the invention further includes means (24) for storing the syndrome of a first data word v, and means (24) for adding the syndrôme a second data word v min , the latter data word v min being generated from the first data word v by means of an "invert write" and an " invert read" procedure. The above addition allows the masking of the single soft error. The invention further includes means (20) for determining whether the result of the above addition provides a syndrome characterizing a single package syndrôme, in order to determine the number of the package having suffered at least one hard error, and means (21, 22, 50-XX) operative in response to said determination for directly locating the positions of the errors, either soft and hard, in order to restore the originally stored data word.