Logic Circuit Output
1. **State the problem:**
We have a logic circuit with inputs A, B, and C.
- A and B go into a NAND gate.
- C goes into a NOT gate.
- The outputs of the NAND gate, the original B, and the NOT gate feed into an OR gate.
- The OR gate output is Y.
2. **Find the output expression Y:**
- NAND gate output: $$\text{NAND}(A,B) = \overline{A \cdot B}$$
- NOT gate output: $$\text{NOT}(C) = \overline{C}$$
- Inputs to OR gate: $$\overline{A \cdot B}, B, \overline{C}$$
- OR gate output: $$Y = \overline{A \cdot B} + B + \overline{C}$$
3. **Simplify the expression:**
- Note that $$\overline{A \cdot B} + B = \overline{A \cdot B} + B$$
- Since $$B + \overline{A \cdot B} = B + \overline{A} + \overline{B}$$ (using De Morgan's law on NAND)
- But $$B + \overline{B} = 1$$, so
$$B + \overline{A \cdot B} = 1 + \overline{A} = 1$$
- Therefore,
$$Y = 1 + \overline{C} = 1$$
- So the output Y is always 1 regardless of inputs.
4. **Evaluate Y for A=1, B=0, C=0:**
- Using the original expression:
$$\overline{A \cdot B} = \overline{1 \cdot 0} = \overline{0} = 1$$
$$\overline{C} = \overline{0} = 1$$
- So,
$$Y = 1 + 0 + 1 = 1$$
**Final answers:**
- (a) $$Y = \overline{A \cdot B} + B + \overline{C}$$ which simplifies to always 1.
- (b) For A=1, B=0, C=0, $$Y=1$$.