WORD LOGIC CIRCUIT

1,108,688. Associative-store. GENERAL PRECISION SYSTEMS Inc. 5 April, . 1966 [4 May, 1965], No. 15118/66. Heading G4C. [Also in Division H3] An associative store is provided with a simplified circuit for controlling the rewriting (or modifying) of the contents of addresses for which match signals are obtained. An associative store (a one-word cell 15 of which is shown in Fig. 1) comprises a non-magnetic wire 15a coated with a thin magnetic film 15b to which a number of digit lines 17-19 are linked. Digits are written by the coincidence of a current in one of lines 17-19 (produced by digit write driver 20) with a current in wire 15a, the currents of opposite polarity for writing the binary digits 1 and 0 respectively being produced in this wire by write drivers 30 and 36 coupled to magnetic cores 11, 12 which may be cleared by clear driver 28 and through which the wire 15a passes. The word to be compared with the contents of the store is stored in address register 22 and by means of interrogate driver 20 produces currents in lines 17-19 having polarities related to the bits in register 22. In those words 15 where there is a mis-match a current is induced in wire 15a, thereby actuating sense amplifier 13 and setting previously cleared cores 11, 12 so that subsequent actuation of drivers 30, 36 has no effect. In those words 15 where there is a match, no current is induced, amplifier 13 is not actuated, the cores 11, 12 remain cleared and on subsequent sequential operation of the drivers 30, 36 respectively the one's and zero's are re-written into the stores 15. A matrix of word stores is illustrated in Fig. 2 (not shown) and in a modified but functionally equivalent embodiment (Fig. 3, not shown) one core only is used, but the sense amplifier 13 is latchable.