A control circuit such as a microcomputer sets only the starting address of the memory in which initial information for generating a maximum length recurring sequence is stored and the number of chips of the maximum length recurring sequence and the initial information for generating a maximum length recurring sequence is set from the memory in the maximum length recurring sequence generator by a hardware. The hardware for accessing the memory is constructed by a counter working with a high speed clock. The number of chips of the maximum length recurring sequence set by the external control circuit is counted by a counter working with a high speed clock.
