24. The method of claim 22 , further comprising a circuit for overwriting an old record in the memory structure with said new record according to the value of said score for the old record and according to whether said old record is a previous node to said new node or to another node in said memory structure.
22. The method of claim 16 , wherein the memory structure is configured to hold a record for each of a plurality of nodes in the lexical tree, the record including said states, a previous node identifier for identifying a previous node in the lexical tree, and information indicating whether said each node is a previous node for another node stored in said memory structure, the speech recognition circuit including a circuit to identify a first node which is not a previous node of another record, and to provide a new data record corresponding to a new node, the new node being the next node after the first node in the lexical tree, using a score associated with the first node.