Question

What is the output Y in the following circuit when all the three inputs A, B, C are first $0$ and then $1$?

• A. $1,1$
• B. $0,1$
• C. $0,0$
• D. $1,0$

Answer 1

Answer: (D)

$1,0$

Here the gate P is a logic symbol of AND gate and Q is a NAND gate.

So, the output of P is $Y_p=A.B$ and the output of Q is

$Y=\overline{Y_p.C}$

When $A=0,B=0,C=0\Rightarrow Y_p=0,Y=\overline{0.0}=1$

When $A=1,B=1,C=1\Rightarrow Y_p=1,Y=\overline{1.1}=0$