Combinational circuits

3

Dept. of Mechatronics Engg.

HALF ADDER . FULL ADDER

Lab 07

4

ADDER

In electronics, an adder or summer is a digital circuit that performs addition of numbers.

In many computers and other kinds of processors, adders are used not only in the arithmetic logic unit(s), but also in other parts of the processor, where they are used to calculate addresses, table indices, and similar operations.

5

Half Adder

The half adder adds two single binary digits A and B

 It has two outputs, sum (S) and carry (C).

The higher significant bit of this result is called a carry ( C)

6

Half Adder

A B c s0 0 0 0

0 1 0 1

1 0 0 1

1 1 1 0

C= MSB S= LSB

Expression S= A’B+ AB’ C= AB

7

Full Adder

C in = carry from last Addition

Cout = Carry for final stage

S= Sum final stage

Expression

A B C in

C out

s

0 0 0 0 0

0 0 1 0 1

0 1 0 0 1

0 1 1 1 0

1 0 0 0 1

1 0 1 1 0

1 1 0 1 0

1 1 1 1 1

8

Implement a Full adder using half adders.

Task no 2

9

Task 03

Design a circuit that can add two, 4 bit numbers.

10

11

TASK 4

Show how two 7483A could be cascaded to add two 8 bit numbers.