| 摘要 |
An error detection system wherein 64 bits of data word are protected by 8 check bits which yield 8-bit syndromes. Single-bit errors are indicated by syndromes that contain exactly three "1"s or by syndromes that contain exactly five "1"s in which bits 0-3 or 4-7 of the syndrome are all "1." Single-bit errors that occur from faulty check bits are indicated by syndromes that contain exactly one "1." All two-bit errors, and four-bit errors within a nibble, are indicated by syndromes that contain an even number of "1"s (i.e., an even number of "1"s). Three-bit errors within a nibble are indicated by syndromes that contain five "1"s in which bits 0-3 of the syndrome and bits 4-7 of the syndrome are not all "1." Four-bit errors within a nibble are indicated by syndromes that contain four "1"s. In another embodiment of the invention, 25 bits of data word are protected by 7 check bits yielding 7-bit syndromes. Single-bit errors are indicated by syndromes that contain exactly three "1" s except single-bit errors that occur from faulty check bits are indicated by syndromes that contain exactly one "1". Two-bit errors are indicated by syndromes that contain an even number of "1"s, and three-bit errors within a nibble are indicated by syndromes that contain five "1"s or seven "1"s. Four-bit errors within a nibble are indicated by syndromes that contain four "1"s or six "1"s.
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