APPARATUS USING ADDRESS OF A PREDETERMINED PRECEDING INSTRUCTION AND TARGET INSTRUCTION ADDRESS STORED IN HISTORY TABLE TO PREFETCH TARGET INSTRUCTION

This data processor makes zero the execution clock count of a branch instruction, a compare instruction, or a compare instruction and following branch instruction when a series of instructions executed in the past is again executed. The data processor of this invention is provided with a history storage unit which stores as its address tag the address of an instruction executed before the branch instruction or compare instruction, and stores the address of an instruction to be executed next the branch or compare instruction or both instruction code of an instruction to be executed next the branch or compare instruction and an address used for pre-fetching an instruction following the instruction code. While the instruction before the branch or compare instruction is decoded, the history storage unit is searched to obtain an instruction to be next executed. The obtained instruction is executed immediately after the execution of the instruction immediately before the branch or compare instruction.