16. A method of speech recognition, comprising providing state identifiers which identify states corresponding to nodes or groups of adjacent nodes in a lexical tree, the lexical tree comprising a model of words; providing scores corresponding to said state identifiers; receiving and storing state identifiers identified by node identifiers identifying a node or group of adjacent nodes in a memory structure; looking up said memory structure to identify particular state identifiers; reading of the scores corresponding to the state identifiers; receiving score updates corresponding to particular state identifiers from a score update generating circuit which generates the score updates using audio input; modifying said scores by adding said score updates to said scores; writing back of the scores to the memory structure after modification of the scores; and selecting at least one node or group of adjacent nodes of the lexical tree according to said scores.
27. The method of claim 16 , wherein the memory structure comprises at least one content addressable memory and at least one random access memory, the content addressable memory being configured to output addresses of the random access memory.