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Error Correction Code Detection with All Memory Outputs Stuck High or Low

IP.com Disclosure Number: IPCOM000113503D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Chan, FL: AUTHOR [+5]

Abstract

Disclosed is an algorithm for providing an Error Correction Code (ECC) which can be detected under the conditions of all data outputs being simultaneously stuck at a high or low level. With this algorithm, while some check bits are generated using odd parity, other check bits are generated using even parity.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 96% of the total text.

Error Correction Code Detection with All Memory Outputs Stuck High
or Low

      Disclosed is an algorithm for providing an Error Correction
Code (ECC) which can be detected under the conditions of all data
outputs being simultaneously stuck at a high or low level.  With this
algorithm, while some check bits are generated using odd parity,
other check bits are generated using even parity.

      The table shows an application of this technique, in which
seven check bits, C0 through C6, are generated according to various
combinations of 32 data bits, labeled 0 through 31.  In each column,
the data bits indicated by the letter "X" are used to generate the
check bit at the top of the column, by means of odd or even parity as
indicated in the "parity" row.

      This technique may be applied, for example, in circuits for
detecting and correcting errors in data read from memory.  Since both
data and parity bits are stored in memory, if all memory outputs are
stuck high, the data read corresponds to the hexadecimal number
FFFFFFFF, while the check bits read correspond to the binary number
111111.  However, this is obviously an error, since the expected
check bits for this hexadecimal number form the binary number
1010101.  Thus, this type of memory failure is easily detected.

      On the other hand, if odd parity is used to generate each check
bit, the expected check bits for this hexadecimal number form the
binary number 1111111.  Therefore, this type of...