PURPOSE: To reduce substancially the amount of hardware, by providing the 1st, the 2nd, the 3rd signal generating means, the 1st, the 2nd, the 3rd signal generating means, n-set of storage means and the 1st, the 2nd and the 3rd OR means.

CONSTITUTION: One word is taken as 4-bit. A control section 1 receives write/ readout request, paallel/serial data and address information via connection lines 12, 13, 14 and generates the serial/parallel data write indication, the address indication signal and the serial data readout indication via connection lines 15, 16, 17, 18. A decoder 4 receives the serial data write indication for the count operation of 0W3, supplies "1" to connection lines 22-1W4 with the count value, and transmits it to a corresponding storage section 6-n. Thus, any shift register converting data from serial into parallel data is not required.