It is proved that for all values of code length n, except when n=2, 4, and 8 and possibly when n=2/sup r/ and n=2/sup r/+1, where r/spl ges/1, the Hamming codes are also optimal systematic single asymmetric error-correcting codes. For the cases n=2/sup r/ and n=2/sup r/+1, r/spl ges/4, when not all information words are used, two efficient systematic 1-asymmetric codes are described.
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