PURPOSE: A device for decreasing an extendable instruction is provided to process a general instruction next to the following extension instruction promptly and to enhance efficiencies of a central processing unit and a program by reading the general instruction and processing the following extension instruction during an execution for using a constant value more than a size of a general instruction being stored in an extension data storing unit by an extension instruction and data which are addresses of a storing device. CONSTITUTION: An instruction storing unit(100) stores instructions comprising a plurality of general instructions and extension instructions. A temporary storing unit(200) comprises a plurality of buffers performing a pre-fetch and storing of a plurality of instructions from the instruction storing unit(100). An instruction searching unit(300) receives a plurality of instructions being pre-fetched from the instruction storing unit(100) to the temporary storing unit(200) and decodes the received instruction and outputs a position signal(POS) displaying a position of a general instruction and a position of an extension instruction. An instruction selection unit(400) receives a position signal(POS) which is an output of the instruction searching unit(300) and may select a buffer storing the corresponding general instruction and may output general instructions successively. A general instruction interpreting unit(700) receives a general instruction being outputted from the instruction selection unit(400) and outputs a plurality of control signals for executing a general instruction. An extension data interpreting unit(500) may receive operands(OPER1¯OPERn) of a consecutive extension instruction being stored in each buffer and may perform a calculating process of the operands(OPER1¯OPERn). An extension data storing unit(600) receives and stores extension data which are outputs of the extension data interpreting unit(500).
