Abstract: A finite state automaton (FSA) may be used to search a stream of input digital code data representing patterns such as text characters, for example, to identify a plurality of designated query words. When a particular one of the sought values of a character or other code element is identified in the input stream, the proper next state for the FSA is typically selected with the aid of a control table memory with multiple entries for each state. According to the invention, the portion of that memory associated with each multiple exit decision state typically consists of only a single word which contains a base state number and a group of indexing bits, one bit for each possible input code element configuration, with set bits corresponding to the multiple values being sought when the FSA is in that particular state. In response to an input code element value that represents a success, an index number is generated from that value and the set indexing bits.

Abstract: The subject of this disclosure is a Finite State Automaton (FSA) used as part of a term detector employed in a digital pattern search system (searcher). In particular the invention includes various advances in the art of FSA design which make the FSA practical for pattern recognition.Specifically, these advances minimize the amount of memory which is required in each FSA in performing pattern recognition, and allow a speed capability such that the searching can be performed at the rate at which a mass storage medium can supply data. The large amount of memory required and the low speed of processing in the prior state of the art made the use of an FSA impractical for most real applications.

Abstract: Bidirectional repeater circuits for bus-lines and the like are described which, when in idle condition, are capable of promptly transmitting binary data signals in either direction with amplification to restore wave form. A control signal is derived from each data signal during its transmission without imposing any time delay upon the transmission, and is used to disable temporarily signal transmission in the other direction. Thus, the repeater is self-contained in the sense of requiring no external control signal for controlling the direction of transmission. Capability for selectively disabling data transmission in both directions under external control can readily be incorporated in the circuits of the invention.

Abstract: Herein described is an information retrieval system for identifying and retrieving recorded information from a mass storage system for use in a central processing system. The described system is an associative crosspoint processor system having an input which communicates with and receives stored information from the mass storage system (e.g. magnetic tape, magnetic or optical disk, etc.) upon command from the central processing system. In the system a key momory stores key words which are then compared with data words stored in the mass storage system.