Bbc Brown, Boveri & Company, Limited

Stefan Zuger

The retrieval of stored data by means of a search word or search key by using, a hashing method. For this purpose, the search key is resolved into a polynomial having the form of ##EQU1## where i=control variable, k=its maximum value, w.sub.i =polynomial coefficient, p=a power of 2, m=number of search keys in an address table stored in the memory (7). The search process occurs by means of a recursive hashing function having the form of ##EQU2## using hashing function tables and address sub-tables stored in the memory. The address compared circuit, having three temporary memories for the polynomial coefficients w.sub.i, a multiplexer, the memory, an adder registers, a comparator, an edge-triggered JK-type flip-flop with an AND gate connected to its output, and a control unit makes it possible to achieve an inexpensive hardware implementation of the search method.

Search system for locating values in a table using address compare

Two circuit arrangements are described for transforming 2.sup.n global addresses used in a control engineering system having several local units into 2.sup.m local addresses used in one of the units of the system. One of these contains several memories in which subfunctions resulting from a splitting of the transformation function conveying the transformation are stored. The other circuit arrangement contains a single memory which accepts all subfunctions. The transformation function is split into the subfunctions in such a manner that an optimum compromise is achieved between the storage space required for storing the subfunctions and the time required for the transformation.

Growing community of inventors

Baden, Switzerland

Stefan Zuger