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Symmetrical Odd Weight (39,32) DED/SEC Code With Package Error Detection

IP.com Disclosure Number: IPCOM000049389D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Johnson, MA: AUTHOR [+2]

Abstract

A double error detection/single error correction (DED/SEC) optimum and symmetrical Hamming Code has been developed that provides package error detection for a 4-bit memory package.

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Symmetrical Odd Weight (39,32) DED/SEC Code With Package Error Detection

A double error detection/single error correction (DED/SEC) optimum and symmetrical Hamming Code has been developed that provides package error detection for a 4-bit memory package.

In a Hamming Code, parity bits are formed on different groups of data bits so that an error in a data bit produces a pattern of syndrome bits that identifies the error so that it can be corrected by inverting the bit. The syndrome bits show a change in the original check bits formed during a store operation and the new check bits formed during fetch on the word that may be in error. In an odd- weight code, an even number of syndrome bits (except zero) signifies a double error. These codes are frequently used with data patterns having fewer than the maximum number of bits so that some additional errors can also be detected. It is advantageous to arrange for all of the errors in a single module or package to be detectable.

In a symmetrical code two identical encoding modules, each implementing one half of the ECC (error correction code) matrix, can be used together with an interconnection scheme which combines the partial syndrome bits generated by each module in a further exclusive-OR function to give the check bits to be stored or the syndrome bits for error decoding. All of the duplicated components are identical, and only the interconnections differentiate the two halves of the circuit.

The following table descr...