Encoding scheme for failure detection in random access memories

A combination for detecting and indicating errors in an information storage system comprising;

• memory means including a plurality of addressable words,
• information handling means,
• memory accessing and registering means, connected to said information handling means and to said memory means, operative to extract and register a word stored in said memory means corresponding to an address provided by said information handling means,
• first encoder means, connected to and receiving inputs from said accessing and registering means, operative to generate a first check code field suitable for use in detecting all multiple unidirectional errors in a first predetermined portion of an extracted word,
• second encoder means, connected to and receiving inputs from said memory accessing and registering means, operative to generate a second check code field suitable for use in detecting at least a single error in the address of said extracted word,
• a first comparator, connected to and receiving inputs from both said memory accessing and registering means and said first encoder means, operative to generate a first error signal whenever said first check code field is not identical to a second predetermined portion of said extracted word,
• a second comparator, connected to and receiving inputs from both said memory accessing and registering means and said second encoder means, operative to generate a second error signal whenever said second check code field is not identical to a third predetermined portion of said extracted word,
• and said information handling means further including means, connected to both said first and second comparators, for processing said first and second error signals, whenever present, to indicate the occurrence of a storage system error.

A method for detecting errors in a digital information storage system, said system including memory means, wherein said memory means include a plurality of individually addressable words and wherein each individually addressable word is further comprised of a data field, a first stored code field related to the data field, and a second stored code field related to the address at which the word is located, and reading means for extracting said words, said method comprising the steps of:

• a. extracting, via said reading means, one of said words;
• b. generating a first check code field suitable for use in detecting all multiple unidirectional errors in the data field of said extracted word;
• c. generating a second check code field suitable for use in detecting at least a single error in the address of said extracted word;
• d. comparing said first stored code field with said first check code field;
• e. comparing said second stored code field with said second check code field;
• f. and generating an error indication whenever said stored code fields do not exhibit a predetermined relationship to their corresponding generated check code fields.

A combination for detecting and indicating errors in an information storage system comprising;

• memory means including a plurality of addressable words,
• information handling means,
• memory accessing and registering means, connected to said information handling means and to said memory means, operative to extract and register a word stored in said memory means corresponding to an address provided by said information handling means,
• first encoder means, connected to and receiving inputs from said accessing and registering means, operative to generate a first check code field suitable for use in detecting all multiple unidirectional errors in a first predetermined portion of an extracted word,
• second encoder means, connected to and receiving inputs from said memory accessing and registering means, operative to generate a second check code field suitable for use in detecting at least a single error in the address of said extracted word,
• a first comparison means, connected to and receiving inputs from both said memory accessing and registering means and said first encoder means, operative to generate a first error signal whenever said first check code field does not exhibit a predetermined relationship to a second predetermined portion of said extracted word,
• a second comparison means, connected to and receiving inputs from both said memory accessing and registering means and said second encoder means, operative to generate a second error signal whenever said second check code field does not exhibit a predetermined relationship to a third predetermined portion of said extracted word,
• and said information handling means further including means, connected to both said first and second comparison means, for processing said first and second error signals, whenever present, to indicate the occurrence of a storage system error.