CEN-120 DIGITAL LOGIC DESIGNBSCS 3-B SPRING 2015

ASSIGNMENT 2

STUDENT NAME: FAHAD ASADREG NO: 36560TEACHERS NAME: SIR RIZWAN ALI

DEPARTMENT OF COMPUTER SCIENCE BAHRIA UNIVERSITY, KARACHI CAMPUSABSTRACTThe purpose of the assignment entitled as HALF ADDER AND FULL ADDER is to understand the concept of half adder and full adder that what they works, how they works, what are their definitions, how many inputs/outputs both they have and how many half adder are required to make full adder.

METHODOLOGY

WORKING: Half Adder circuit uses 2 ICs one is 7486 XOR gate IC and the other one is 7408 AND gate IC. Both ICs have four gates in them. These ICs have 14 no pin for Vcc. 1,2,4,5,8,9,11 and 12 no pin is for inputs . 3,6,10 and 13 no pin is for getting output and 7 no pin is a ground pin. In Half Adder two input were given to XOR GATE in the form of 1,0 logic and the same inputs were given to AND GATE the output of XOR gate gives us the SUM and the AND GATE output gives us the carry.Full Adder circuit also uses these ICs but also use one additional IC 7432 OR gate IC have same pin configuration. In Full Adder we give input A and B to both 1st AND GATE and XOR GATE than output of XOR gives as input to the second XOR and Carry in as input to 2nd XOR GATE and output of AND GATE gives as input of 2nd AND GATE and give the same carry in as input of 2nd AND GATE the output of both 2nd AND gate gives as an input of OR GATE. The output of OR GATE shown as a carry and the output 2nd XOR GATE shown as an SUM.

BREADBOARD DIAGRAM PICTURE:Half Adder:

Full Adder:

LOGICAL CIRCUIT DIAGRAM:

Half Adder:

Full Adder:

TRUTH TABLE:Half Adder:InputsOutputs

ABCout ( Carry out )S (Sum)

0000

1001

0101

1110

Full Adder:InputsOutputs

ABCin( Carry in )Cout ( Carry out )S (Sum)

00000

10001

01001

11010

00101

10110

01110

11111

What is Half Adder and Full Adder?HALF ADDER:In half adder, two bits are being added to produce sum and output carry.FULL ADDER:In full adder, two bits and carry in bit are being added to produce sum and output carry.

How they works, how many inputs/ outputs they have and how many half adder required to make full adder?Half Adder have two binary inputs and two binary outputs. Let the inputs be A & B. The first order output will be called S because it represents the sum and the high order output will be called C, because it represents the carry output.Full Adder have three binary inputs and two binary outputs. Two of the input variables represent the two significant bits to be added. The third input represents the carry input from the previous lower significant position. Sum and carry out performs same operation in half adder, but here it add the three binary inputs.Two half adders are required to make full adder.

RESULTSIn half adder, if we gives input of (1,1), (1,0), (0,1) then LED will be on and if we gives input of (0,0), then LED will off.

In full adder, if we gives input and carry in of(1,1,1), (1,1,0), (1,0,1) then LED will be on and if we gives input and carry in(0,0,0) then LED will be off.

CONCLUSIONI have successfully completed the assignment report and also I have also verified the concept that what is the importance of half and full adder in the digital world.