PURPOSE: To retrieve a desired bit train corresponding to a retrieving bit and its position from a bit train to be retrieved, consisting of many bits, by a coincide- processing operation of only the number of bits portion which a retrieving word has.

CONSTITUTION: A bit train to be retrieved (m) of 15 bits is inputted to an A- register, and 3 groups of retrieving words (n) of 4 bits each are inputted to a shift register B. In a shift register C, it is placed so that the last bit position of each retrieving word is known and "1" comes to its position only. Subsequently, the register A and the shift register B are made to coincide through coinciding circuits 4-1, 4-2..., its result is inputted to a register E, is provided to a shift register D, too, and 1 bit is shifted in the right direction by the shift register D. Subsequently, AND of contents D1 of the register D and contents E1 of the register E is taken through AND circuits 6-1, 6-2..., its result is inputted to the register E again, and also in this case, the register D is shifted to the right. Thereafter, the operation processing is executed by the bit number of the retrieving word (n), and thereafter, AND of the registers E, C in which the last value is inputted is taken.