PURPOSE: To prevent a waste part from being generated at a storage part by applying address conversion on an address outputted from an address generation circuit, and setting a conversion address as an input to a decoder.

CONSTITUTION: When both a row address and a column address outputted from the address generation circuits 1 and 2 show zeros, both the low address and the column address of the storage part 7 are conformed to zero. Next, when the row address outputted from the address generation circuit 1 is increased by one, the row address of the storage part 7 is conformed so as to be increased by one. Also, for various kinds of maximum values of the addresses outputted from the address generation circuits 1 and 2, the address conversion corresponding to them are applied. The conversion address is inputted to the decoders 5 and 6.