| 摘要 |
PURPOSE:To decrease the number of steps of a microinstruction by selecting the microinstruction or the output of an arithmetic processing signal generating circuit by the microinstruction itself and giving the arithmetic designation to an arithmetic circuit from the result of said selection. CONSTITUTION:A ROM10 stores the arithmetic designation information containing the arithmetic type of an instruction and the arithmetic data width according to an instruction code. An arithmetic processing signal generating circuit 11 selects a microinstruction or the circuit 10 according to the contents of said microinstruction. Based on the result of this selection, the arithmetic is designated to arithmetic circuits 12 and 13. Thus several types of instructions can be processed in the addresses of the same microprogram. This attains reduction of the number of steps of a microprogram. |
