Q.Draw the logic symbol, timing diagram and truth table of half adder/ half subtractor.

A half adder adds two bits giving a sum and a carry; a half subtractor subtracts two bits giving a difference and a borrow. …

[!TLDR]

Half adder: sum $S=A\oplus B$, carry $C=AB$; half subtractor: difference $D=A\oplus B$, borrow $B_o=\overline{A}B$.

Half adder — adds two single bits $A$ and $B$.

• Logic symbol: a block with two inputs $A, B$ and two outputs $S$ (Sum) and $C$ (Carry); internally an X-OR gate gives $S$ and an AND gate gives $C$.
• Boolean: $S = A\oplus B = \overline{A}B + A\overline{B}$, $C = A\cdot B$.

Half subtractor — subtracts $B$ from $A$.

• Logic symbol: a block with inputs $A, B$ and outputs $D$ (Difference) and $B_o$ (Borrow); an X-OR gate gives $D$, and an AND gate with the $A$ input inverted gives $B_o$.
• Boolean: $D = A\oplus B$, $B_o = \overline{A}\cdot B$.