Question

The inputs to the digital circuit are shown below. The output Y is.

• A. $A+B+\overline{C}$
• B. $(A+B)\overline{C}$
• C. $\overline{A}+\overline{B}+\overline{C}$
• D. $\overline{A}+\overline{B}+C$

Answer 1

The correct option is C $\overline{A}+\overline{B}+\overline{C}$

A and B are inputs to the NAND gate. The output of that gate is $\overline{(A.B)}=\overline{A}+\overline{B}$.

The output of C being input to the NOT gate is $\overline{C}$.

These two are inputs of OR gate.

Hence $Y=\overline{(A.B)}+\overline{C}$

$=\overline{A}+\overline{B}+\overline{C}$