PURPOSE: To supply the address of a selected data sequence rapidly by assigning respective address registers independently to plural data strings.

CONSTITUTION: Three data sequences are stored in a data RAM 20 and the addresses of respective data sequences are stored in address registers 21W23. Information indicating which data sequence is to be accessed is applied to a selector 24 and a distributor 30 by a control circuit 27. The address of a selected data sequence is temporally stored in a register 25 and applied to the data RAM 20. Then, an increased value is added to the output of the register 25 by an adder 29 to modify the output and the modified output is outputted to the same address register selected by the selector 24 as the succeeding address of the selected data sequence.