PF474

The PF474 is designed as one kind of new device which implements the revolutionary string proximity computer and ranker on a single VLSI silicon chip using high-speed NMOS technology.The string proximity computer(United Ststes and foreign patents pending) is a state-of-the-art device that compares two symbol strings to arrive at a numeric rating of their similarity;a 32-bit binary fraction ranging between zero and one.This highly sophisticated measure of similarity is very flexible and adaptable to a wide spectrum of applicantions.It is useful to think of the PF474 as a scoring device that produces high scores for very similar strings and low scores for highly dissimilar strings.Typically,the PF474 is used to search a list of symbol strings(a database for example) for entries that are most similar to a query which is fixed for the duration of the operation.When the operation is complete,the ranker portion of the device can be accessed to identify which members of the list received the highest scores.

Features of the PF474 can be summarized as:(1)computes 32-bit proximity values;(2)processes strings with lengths of up to 1278-bit symbols;(3)maximum throughput of 66,110 comparisons and rankings per second for strings of 8 characters(PF474-40);(4)parameter tables,stored in externally accessible RAM, allow tailoring of the proximity function;(5)maintains internal 16-element ranked list of best matches;(6)permits location of 15 additional next best matches;(7)modern programming architecture allows the device to be accessed as normal memory;(8)high-speed DMA facility permits rapid loading from external memory:up to 2 million bytes per second;(9)fits naturally and simply into microprocessor based systems.etc.