Information retrieval system serially comparing search question key words in recirculating registers with data items

Claim 1

An information retrieval system comprising: a plurality of recirculating registers for storing a corresponding plurality of key words representing retrieval search questions; a corresponding plurality of comparators, each corresponding to a register; a storage device for storing a plurality of data items each comprising at least one key word whose format is the same as that of the search question key words and an associated code identifying an associated document; means for synchronously applying to each comparator the contents of the corresponding recirculating register and each of the key words of the data items in succession, from at least one of a plurality of data items from said storage device; a plurality of flip-flops, each corresponding to one of said comparators; means for setting each flip-flop upon coincidence of the key words applied to its corresponding comparator; gate output means including register means for receiving the code of the data item whose key words have been compared with the contents of the recirculating registers and responsive to the coincidence of the set state of all flip-flops for gating out the received code; and means for selectively causing selected flip-flops to be set upon the setting of at least one other selected flip-flop, whereby said code may be gated out of the gate output means upon the coincidence of only one or more of said plurality of search question key words with a corresponding key word of a data item, said code word being available for use in locating an associated document.