NIMCET 2007 — Computer PYQ

Step 1: Identify the Logic Gates in the Circuit

By analyzing the schematic diagram in the problem:

1. The first gate on the left is an XOR gate (Exclusive OR). Its inputs are $A$ and $B$.

2. The second gate on the right is a NOR gate (OR gate followed by an inversion bubble). Its inputs are the output of the XOR gate and the line branching directly from input $B$.

Step 2: Trace the Outputs Step-by-Step

1. Analyze the XOR Gate

The inputs given are:

$$A=1$$

$$B=0$$

The boolean expression for the output of an XOR gate is $Y_1=A\oplus B$. Let's check its truth table values:

• When inputs are different ($1$ and $0$), the output of an XOR gate is always $1$.

$$Y_1=1\oplus 0=1$$

2. Analyze the NOR Gate

The inputs entering the NOR gate are:

• Upper input = Output of the XOR gate ($Y_1=1$)

• Lower input = Transmitted directly from terminal $B$ ($B=0$)

The boolean expression for a NOR gate output ($Y_{\text{final}}$) is:

$$Y_{\text{final}}=\overline{\text{Upper Input}+\text{Lower Input}}$$

Substitute our calculated signals into the expression:

$$Y_{\text{final}}=\overline{1+0}$$

Since $1+0=1$ in Boolean logic:

$$Y_{\text{final}}=\overline{1}=0$$

Conclusion

The final output signal delivered by the combinational circuit is $0$.

Final Answer

The correct option is (a) 0.