Browse Prior Art Database

Robust Complement/ Recomplement Method

IP.com Disclosure Number: IPCOM000107637D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Aichelmann Jr, FJ: AUTHOR

Abstract

A method is proposed which prevents hidden faults from limiting the effectiveness of the complement/recomplement (CRC) recovery algorithm. This method improves this limitation by correcting some of these alignments.

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This is the abbreviated version, containing approximately 68% of the total text.

Robust Complement/ Recomplement Method

       A method is proposed which prevents hidden faults from
limiting the effectiveness of the complement/recomplement (CRC)
recovery algorithm.  This method improves this limitation by
correcting some of these alignments.

      The conventional CRC recovery algorithm does not clear the
uncorrectable error because the hidden fault is added as an
additional fault due to the complementing procedure. This proposal
overcomes this limitation by adding an "initial value register" and a
"comparator" to the ECC facility.  The "initial value register" latch
traps the original data before the CRC process is invoked.  After the
inversion procedure the "comparator" is used to detect the stuck at
faults.  The ECC facility can then determine the validity of the
syndromes and use only the true valid syndrome.

      Fig. 1 is an H matrix example which will be used to demonstrate
this method.  Identified in this H matrix are the locations that will
be used as an example.  Fig. 2 shows the added logic associated with
this method.  If multiple valid syndromes occur this method cannot be
used.

      The following demonstrates this method:
      Initial fetch from memory error syndrome = 00100010
      After inversion (soft & hidden) error syndrome = 10100011
      Stuck at location syndrome (from comparator) bit 15 - 01001010
bit 27 - 00110100
      Error syndrome (before inversion) with stuck at bit locatio...