| 摘要 |
PURPOSE:To deal with the specified value of a non-numeric or the like without adding an instruction by constituting so as to compare-output the specified value and the contents of an operand with a same instruction code by a comparing means when the contents indicated by an assigning means and the instruction code are assigned as the specified values. CONSTITUTION:A specified value comparing part 3 is provided in an arithmetic unit 2, when the device is actuated in an IEEE floating point standard form, a non-numeric is transferred as a specified value to it and when an instruction decoder 5 decodes a non-numeric detecting instruction, it is made to be detect- controlled whether read data are the non-numeric or not. That is, when the device is actuated in the IEEE floating point standard form, the instruction read from an instruction fetching part 4 is decoded by the instruction decoder 5 and when it is the non-numeric detecting instruction, an instruction transmission control part 6 transmits the decoder to the specified value comparing part 3 based on it and makes it execute checking whether it is the non-numeric or not. Thus, the operation of a conventional floating point form and the IEEE floating point standard form can be executed selectively with a small hardware quantity. |
