47. A speech recognition circuit according to claim 46 , wherein each lexical memory stores lexical data as at least one lexical tree data structure, each lexical tree data structure comprises a model of words having common prefix components, and an initial component of each lexical tree data structure is unique.
55. A speech recognition circuit according to claim 47 , wherein said control processor instructs a said processor to process a lexical tree by passing a lexical tree identifier for the lexical tree and history data for a recognition path associated with the lexical tree to said processor.