PURPOSE: To enable an automatic programming by storing the addresses of the locations of programs and changed data, etc., in a writable nonvolatile memory by two address registers and two information registers and supplying the voltage required for a writing, by a processing control means.

CONSTITUTION: A processing controller 104 controls the synchronization of the data exchange in a bus line D and the addressing of a memory 101, and the outputs 2 and 3 control the readings of the data from each register A1 and A2 and B and IR and the writing of data in the register. When data is in process of being written in the memory 101, programming voltage Vp is supplied. The processing controller 104 performs the program change of the memory, performs the inputs/outputs of information between the address registers A1 and A2 and information registers IR and D and simultaneously executes a normal instruction sequence. Thus, a simultaneous duplex access becomes possible and an automatic programming can be performed.