Encoding don't cares in static and dynamic content-addressable memories

An encoding scheme for don't cares using two binary static content-addressable memory (CAM) cells is presented. No extra hardware is required for the storage and retrieval of don't cares beyond the hardware necessary for binary write and match operations found in most commercial static CAMs. Besides the availability of proven hardware for binary CAM chips, this implementation has the advantage that both binary and ternary values can coexist in a single CAM word.>