| 摘要 |
PURPOSE:To attain subtraction not only to continuous and circulating numerical values but to discontinuous and circulating values, by using a complement circuit, an adder and a selector. CONSTITUTION:A complement circuit 1 secures the complement of '2' for data 11 showing a subtraction number, and the data 11 is turned into data 12. This data 12 passes through a selector 3 and is added with data 14 showing a number to be subtracted through an adder 4. Then data 17 showing the result of addition is delivered. When the data 17 has a carry, an electric signal 20 is outputted from the adder 4. In this case, the data 17 shows the desired result of subtraction. When no signal 20 is delivered, the data 17 is invalidated. Under such conditions, the data 12 is added to the data 15 showing the (upper limit +1) of a numerical range through an adder 2. Then data 16 showing the result of said addition is switched by the selector 3 and added with the data 14 through the adder 4. Then the data 17 showing the result of this addition means the desired result of subtraction. |
