PURPOSE: To make software development efficient and to improve the throughput of a CPU by controlling the interval of accesses to a peripheral circuit by a circuit in a CPU.

CONSTITUTION: An arithmetic execution unit 101 inputs a program or the like through buses 113, 114 and executes the program. A determination unit 103 checks the value of a counter 104 by a counter signal 108 in accordance with a bus cycle request signal 109. The counter 104 controls the interval of accesses to the peripheral device for slow operation. An initial value is transferred from a register 105 to the counter 104 in accordance with a control signal 107. When the value of the counter 104 is not '0', execution program are read in through buses 113, 111, 112. The programs are successively stored in a prefetch queue 106 and read out to the unit 101 through a bus 114.