PURPOSE: To enable to easily store the operation log of the instruction without debasing the efficiency, by using the address which has accessed the memory device, and adding "1" to the contents of the corresponding address of the log memory part whenever the instruction is output.

CONSTITUTION: When a signal (b) for starting the memory device 11 is made "0", a chip selective signal (h) to the log memory part 16 becomes "0", and the memory part 16 is started. The A address is provided to the address signal (a) of the terminal 12, and the instruction is input to the address A of the device 11, and therefore, a signal (d) of the instruction read-out signal terminal 21 becomes "1". Accordingly, a signal (g) which can be written to the memory part from the control part 18 is output from the terminal 27. Also, since an addition approval signal to the adder circuit 17 becomes "1", the contents which have been read out from the address A of the memory part 16 are added by "1", and are written again to the address A. In this way, frequency of the address to which the instruction has been accessed is stored in the corresponding address of the memory part 16.