PURPOSE: To reduce greatly the capacity of a static memory by storing an address in a memory means for accesses to the next address of said memory means and an instruction table.

CONSTITUTION: The next address is stored in a memory 10, and an effective microinstruction is stored in a ROM11. The next address read out of the memory 10 consists of addresses which give addresses to memories 10 and 11. For former address is held temporarily by an address register 12 and designates the next address of the memory 10. While the latter address is held temporarily by an instruction address register 13. The register 13 gives an access to the instruction stored in the memory 11. The instruction read out of the memory 11 is latched by a latch circuit 14 and sent to an execution circuit 15 to be executed there. The result of this execution is stored in the register 12.