Content addressable memory apparatus

1,056,240. Digital data storage apparatus. BUNKER-RAMO CORPORATION. Nov. 27, 1964 [Dec. 30, 1963], No. 48386/64. Heading G4C. A content-addressed memory which allows for search by a variable-length search word comprises a search store 20 into which the search data is loaded in the form of a number of separate search words, a register 12 which receives these search words successively over gates 26 and interrogates the memory matrix 10 in respect of each of them, flip-flops 42, 46 &c. which record the result of the interrogation, and gates 38 which, after each interrogation, transfer the " match " indication downwardly. The number of words forming the search data is recorded in 22 and, when these have all effected interrogation, gates 38 are closed. Fip-flops 42 &c. are reset by mismatch signals so that if and only if a sequence of words in 10 corresponds to the sequence of search words will the flip-flop corresponding to the last word of the sequence in 10 be set at the end of the search.