Combined Modular Key and Data Error Protection for Content-Addressable Memories

Content-addressable memories (CAMs) are a type of memory that receives an input search key and compares it to every entry of a table of stored keys. If there is a match, they return the corresponding address where the value was found. Alternatively, they can include a related Random Access Memory (RAM) that is accessed with the matching address, returning the corresponding data values. To protect a CAM with associated RAM against errors, parity or error-correction codes (ECCs) are typically used. They usually protect the CAM and the RAM information separately incurring in additional storage needs. This paper proposes a scheme to protect some configurations of CAM with its associated RAM from errors with a single ECC code. This ECC code can be used to provide advanced error correction to the combination of the key and data values stored in the CAM and the RAM, but it can also be applied in a modular way to provide simpler protection to the key or to the values individually.