Question

What operation is performed by the given circuit?

• A. B to G Converter
• B. Subtractor
• C. Multiplier
• D. None of the above

Hint:

Subtraction can be implemented using addition by converting the second operand into its Two’s Complement form (\(\bar{B} + 1\)).

Answer 1

The Correct Option is B

Understanding the Circuit.
The given circuit consists of:
- A Full Adder (FA)
- An XOR gate that inverts \( y \) (i.e., \( y' = y \oplus 1 = \bar{y} \))
- A Carry-in value of 1
Binary Subtraction via Two’s Complement: \[ A - B = A + \bar{B} + 1 \] Here:
- \( x \) is directly passed to the FA.
- \( y \) is complemented via XOR with 1.
- Carry-in = 1.
This is the standard way to perform subtraction using addition, confirming that the circuit acts as a subtractor.