Department of Mathematics and Computer Science
CSU 2178- Digital Computer Fundamentals
Practical Guide
Author: Mr. Budditha Hettige.
This guide must be used to do practical sessions in the department.
Introduction
Now you are ready to the Digital electronic practical. First you must read this guide carefully.
Also you get an idea about basic electronic such as resister, DC Power, how measuring the
DC Voltage etc.
Required Components for the Practical.
Before start the Digital electronic practical you must sure following components are available
in your desk. (After practical session you must return all the components)
1.
2.
3.
4.
5.
6.
7.
5V DC Power Supply
Bread Board
Digital ICs (7400, 7402, 7404, 7408, 7432, 7486)
Resistors (390 Ohms, 1KOhms)
LEDs (Red, Green)
Multi Meter
Wires and cutting tools
Experiment 01- Check Power Supply
In the Digital Electronic Practical, We use only 5V DC Power Supply. Now check your
power supply voltage.
Steps
1. Change 0-10v DC Range in to your multi meter
2. Measure your supply voltage.
3. Identify positive and negative nodes.
Experiment 02- Identify your Experimental board (Breadboard)
You breadboard fin connection diagram as follows
Use multi meter and check your breadboard pin connections
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Experiment 03- Fix the power supply in to your experimental board (Breadboard)
Power Supply
5V DC
(0 )
( +)
Experiment 04- Create Power Indicator light
Use a LED bulb and create a simple power indicator. Your power source is 5V DC, but LED
bulb Works on 2V(2.2v) DC Voltage and draws 10mA current, therefore you must use
resister. (DO NOT USE LED without resister)
Resister
Wire Connecter
LED
Circuit
Bread Board Connections
Experiment 05 - Get an idea about representation of the logic 0 and 1
In the Digital Electronics we use logic 5V DC as ‘1’ and Logic 0V as ‘0’ (If you need input
logic ‘1’ you can use 5V DC also Logic ‘0’ you can use 0V.
Experiment 06- Gets an idea about Digital IC
Digital ICs have 2 series, TTL and CMOS, TTL ICs are
numbered 74XX and CMOS are numbered as 4XXX.
All the Digital ICs required 5V DC stable power supply.
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Experiment 07- Use 7404 (NOT GATE) identify how NOT gate is work
Input
390 Ω Resister
LED
7404
Ware Connecters
LED ON = Logic ‘0’
LED OFF = Logic ‘1’
Do the following steps
1. Remove power in your breadboard
2. Fix 7404 Digital IC in your bread board
3. Create an output indicator to display output (Fix LED bulb with resister to see the out
put stage)
4. Add power in to IC (Carefully do this one otherwise, your IC can be damaged)
5. Set logic 1 (5 V) in to input for the Gate.
6. See the Output (Is LED is on or off describe the result)
7. Set logic 0 (0 V) in to input for the Gate.
8. See the Output (Is LED is on or off describe the result)
Experiment 08- Using 7408 (AND GATE) identify how not gate is work
INPUT A
0V
0V
5V
5V
INPUT B
0V
5V
0V
5V
OUTPUT
?
?
?
?
Do the following steps
1. Remove power in your breadboard and remove all component
2. Fix 7408 Digital IC in your breadboard
3. Create an output indicator to display output (Fix LED bulb with resister to see the out
put stage)
4. Add power in to IC (Carefully do this one otherwise, your IC can be damaged)
5. Set inputs in the Gate(input combinations are given in above table)
6. See the Output (Is LED is ON or OFF. Describe the result)
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Experiment 09- Use Unknown Gate and identify it
Unknown Digital IC data sheet is given bellow. A, B are inputs and Y is the output of the
gate. In one IC contain 4 gates. Now using this data sheet you are identify the above gate.
X
Do the following steps
1. Remove power in your breadboard and remove all component
2. Fix Digital IC in your bread board
3. Create an output indicator to display output (Fix LED bulb with resister to see the out
put stage)
4. Add power in to IC
5. Set inputs combinations in to gate
6. See the output of the all input combinations stage.
7. Draw a truth table and identify gate.
Experiment 10- Check the output of the Equation
F = (A+B)
Steps
1. Remove power in your
breadboard and remove all
component
2. Fix Digital ICs in your
breadboard
3. Design the circuit
4. Create an output indicator to
display output (Fix LED bulb
with resister to see the out put
stage)
5. Add power in to IC
6. Set inputs combinations in to gate and check the output.
7. Draw the truth table.
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Additional Exercises
Experiment 11- Use 2 input NOR Gate and create S-R Flip –flop
Steps
1. Fix Digital ICs in your bread board
2. Design the Circuit
3. Create an output indicators to display output (Fix LED bulb with resister to see the
out put stage)
4. Set inputs and check the out put of the circuit
5. Fill the Truth table given bellow
INPUT A
0
0
0
1
0
0
1
1
INPUT B
0
1
0
0
0
1
0
1
OUTPUT 1
?
?
?
?
?
?
?
?
OUTPUT 2
?
?
?
?
?
?
?
?
Experiment 12- Create D Flip-Flop inserting the following additional circuit
Steps
1. Add above circuit in to your circuit(Experiment 12)
2. Set the input and see the output
2. Draw the truth table.
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DATA SHEET (7400, 74002, 7404, 7408, 7432,7486)
2 INPUT NAND GATE
2 INPUT NOR GATE
NOT GATE
2 INPUT AND GATE
2 INPUT OR GATE
2 INPUT XOR GATE
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