PURPOSE: To shorten the initializing time of a memory by inputting the initialized address of the memory fitting in the timing of the operation of a counter by an address register.

CONSTITUTION: When an initialization start signal is sent from a controller 1 to a control circuit 5 via a system bus to initialize the memory 2, initializing work is started by the output of a differentiation circuit in the control circuit 5, and the address register 3 functions as the counter, then, counting is performed until carry out is issued. An address is sent from the address register 3 to the memory 2 at every counting, and also, a write enable signal is sent to the memory 2 at every counting, and data is sent to the memory 2 via an input/output control circuit 4 corresponding to the address from the address register 3. Therefore, the initialization of all of the addresses can be performed by the counting of the address register 3. In such a way, it is possible to shorten the initializing time of the memory 2.