1-bit binary subtraction (borrow logic): Compute 1 − 1 and report the difference and borrow.

Introduction / Context:Single-bit subtraction defines core behavior for multi-bit subtractors. When the minuend bit equals the subtrahend bit and no prior borrow exists, the result is straightforward.

Given Data / Assumptions:

• Subtracting a = 1 by b = 1.
• No incoming borrow (borrow_in = 0).

Concept / Approach:For one bit: difference = a xor b xor borrow_in; borrow_out = (~a & b) | ((~a | b) & borrow_in). With a=b=1 and borrow_in=0, difference=0 and borrow_out=0.

Step-by-Step Solution:

Verification / Alternative check:Decimal view: 1 − 1 = 0 with no need to borrow.

Why Other Options Are Wrong:

Common Pitfalls:Forgetting to specify borrow_in assumptions.

Final Answer:difference = 0 borrow = 0