PURPOSE: To further shorten the access time of a main storage device on a con- tinuous readout system by interrupting a readout of instructions following a jump system instruction when the instruction stored in a buffer memory is the jump system instruction.

CONSTITUTION: Plural instructions are read out successively in single-time operation under the control of a control part 2. Those instructions are stored in an IR file 4 as a buffer memory and also sent to an instruction decoder 5 to decide on whether each instruction is an instruction of the jump system or not. When it is decided that some instruction is an instruction of the jump system, the control part 2 and an arithmetic processing part 6 are commanded to interrupt the readout operation of the main storage device, and the instructions stored in the IR file 4 are sent to the arithmetic processing part 6 and executed. When the instruction is none of instructions of the jump system, the arithmetic processing part 6 sends an indication of the start of memory access to the control part 2.