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Syndrome Generation With Inverted Data

IP.com Disclosure Number: IPCOM000101037D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

LaBerge, PA: AUTHOR

Abstract

In a functional memory card application that does complement or recomplement, the data is recomplemented before calculating the ECC syndrome bits which adds delay to the ECC path. Described is a technique which provides a method of calculating the correct syndromes with the complemented data to shorten the ECC time.

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This is the abbreviated version, containing approximately 88% of the total text.

Syndrome Generation With Inverted Data

       In a functional memory card application that does
complement or recomplement, the data is recomplemented before
calculating the ECC syndrome bits which adds delay to the ECC path.
Described is a technique which provides a method of calculating the
correct syndromes with the complemented data to shorten the ECC time.

      In many functional memory applications, complement/recomplement
is performed when a multi-bit error is detected.  The data with the
multi- bit is complemented and stored back in memory.  It is then
fetched back, recomplemented, and then passed through ECC.  The XOR
gate to do the recomplement is added to the ECC path, even when the
data is not being recomplemented.  This adds path delay that is not
necessary for normal ECC correction.  Fig. 1 shows the data path of
this feature through the ECC circuitry.

      Since the ECC Syndrome calculation is performed by an XOR tree,
the calculated syndrome will be the same for the inverted data if
there is an even number of data inputs into the XOR tree.  If there
is an odd number of data inputs into the XOR tree, the calculated
syndrome of the inverted data will be inverted.  If the recomplement
data control is tied to the unused input of the XOR trees with odd
number of data inputs, the calculated syndrome will now be the same
for the inverted data.  The XOR to recomplement the data can then be
done in parallel with the ECC tree.  This shortened...