Implicit-storing and redundant-encoding-of-attribute information in error-correction-codes

This paper proposes implicit-storing to extend the logical capacity of a memory array without increasing its physical capacity by leveraging the array's error-correction-codes to infer the implicitly stored bits. Implicit-storing is related to error-code-tagging, a technique that distinguishes between faults in data and invariant attributes of a location when the attributes are not stored in the memory array but are encoded in the error-correction-codes. Both error-code-tagging and implicit-storing cause a code-strength reduction due to their encoding of additional information in the code meant to only protect data. Redundant-encoding-of-attributes is introduced to improve the strength of a code by encoding same information in multiple code words in a cache or memory. We demonstrate how EREA and IREA, two derivatives of redundant-encoding, alleviate the code-strength reduction experienced by error-code-tagging and implicit-storing respectively. Implementing the proposed methods requires minor modifications in the encoding and decoding logic of the baseline error-correction scheme used in this work. The paper discusses several uses of the proposed schemes to help demonstrate their usefulness.