If an input of a multiinput logic gate is not used then it s

If an input of a multi-input logic gate is not used, then it should be set to a certain logic value (either 0 or 1) to ensure that the unused input does not float to an unknown or unwanted value. in other word, the outputs depends only on the other inputs. For the following six three-input logic gates, determine the logic value for the unused inputs(UNUSED) so that the logic operations work on the other two inputs only.

Solution

a. In an AND gate atleast one 0 will make the whole value to be 0. Therefore, to return X.Y as output, the UNUSED value should be set to 1.

b. In a NAND gate, if atleast one 0 will make the whole value to be 1. Therefore, to return (X.Y)\' as output, the UNUSED value should be set to 1.

c. In an OR gate, if atleast one 1 will make the whole value to be 1. Therefore, to return X+Y as output, the UNUSED value should be set to 0.

d. In a NOR gate, if atleast one 1 will make the whole value to be 0. Therefore, to return (X+Y)\' as output, the UNUSED value should be set to 0.

e. In an XOR gate, if the UNUSED is set to 0, the whole output, is based on the values of X, and Y, i.e., X xor Y. Therefore, UNUSED value should be set to 0.

f. In an XNOR gate, if the UNUSED is set to 0, the whole output, is based on the values of X, and y, i.e., X xnor Y.

Therefore, UNUSED value should be set to 0.