1. Draw truth table and logical diagram of half adder. (Dec 2015) (5 Marks)

• Half adder is a combinational logic circuit with two inputs and two outputs. It is the basic building block for addition of two “single” bit numbers. This circuit has two outputs namely “carry” and “sum”. Truth table of half adder is given below: | Inputs | Outputs | |--------|---------| | A | B | Sum | Carry | |---|---|-----|-------| | 0 | 0 | 0 | 0 | | 0 | 1 | 1 | 0 | | 1 | 0 | 1 | 0 | | 1 | 1 | 0 | 1 | Logical Equation:

Sum= A’B + AB’ Carry= AB

Logical diagram is as follows: