INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Digital Logic Design Laboratory
Lab 3
MSI Combinational Logic (II)
Full name: Nguyễn Phước Trọng Nhân
Student number:EEEEIU22076
Class: ……………………………………………….......
Date: …………………………………………………....
Digital Logic Design Laboratory 1-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
I. Objectives
In this laboratory, students will study:
- Understand the operation of combinational logic circuit.
- The operation of some combinational ICs such as: full adder, decoder, encoder.
II. Procedure
1. Design the adder with two one-bit binary.
a. Design the half adder two one-bit binary.
Two inputs are A, B. Two outputs are S and C.
Build the truth table and the expressions
A B S C
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
The simplified expressions:
C expression: f(A,B)=AB
S expression: f(A,B)= AB’+A’B
Implement the circuit via simulation software and paste the result in here
Digital Logic Design Laboratory 2-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Make comment on the results
- Regarding the result, the half adder logic gates can be implemented using digital
circuit design software or physical logic gates to test the functionality of the circuit.
Once tested, it is an efficient and essential component in digital systems.
b. Design the full adder two one-bit binary.
Three inputs are Cin, A, B. Two outputs are S and Cout.
Build the truth table and the expressions
A B Cin S Cout
0 0 0 0 0
0 0 1 1 0
0 1 0 `1 0
0 1 1 0 1
1 0 0 1 0
1 0 1 0 1
1 1 0 0 1
1 1 1 1 1
Digital Logic Design Laboratory 3-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
The simplified expressions:
S = A’ + B’ + C’in
Cout = (A . B) + (A . Cin) + (B . Cin)
Implement the circuit via simulation software and paste the result in here
Make comment on the results
-The full adder two one-bit binary circuit, as detailed above, is a fundamental
component for implementing digital arithmetic. Its simplicity and functionality make it
a widely used building block in electronic design automation.
Digital Logic Design Laboratory 4-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
2. 8-to-3 Priority Encoder (Interrupt sorter) – IC 74HC148
a. Investigate IC – 74HC148
Construct the circuit as below:
Figure 1 – Encoder 8-to-3 IC 74LS148
- The outputs are connected to LED displays to determine the logic levels.
- Choose the input data D0 - D7 by switches in the order from SW0 to SW7.
- Control EI by using switch.
- Observe the results and fulfill the truth table of 74HC148.
- What are the functions of GS and EO ?
Input Output
EI D0 D1 D2 D3 D4 D5 D6 D7 GS A2 A1 A0 E0
1 X X X X X X X X 1 1 1 1 1
0 1 1 1 1 1 1 1 1 1 1 1 1 0
0 X X X X X X X 0 0 0 0 0 1
0 X X X X X X 0 1 0 0 0 1 1
0 X X X X X 0 1 1 0 0 1 0 1
0 X X X X 0 1 1 1 0 0 1 1 1
0 X X X 0 1 1 1 1 0 1 0 0 1
0 X X 0 1 1 1 1 1 0 1 0 1 1
0 X 0 1 1 1 1 1 1 0 1 1 0 1
0 0 1 1 1 1 1 1 1 0 1 1 1 1
Implement the circuit via simulation software and paste the result in here
Digital Logic Design Laboratory 5-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
b. Priority encoder
Let’s EI equal to 0, fill the outputs A2, A1, A0 in the following cases
A2 A1 A0
Case 1: 1 0 0
I3 = I2 = I1 = 0
I7 = I6 = I5 = I4 = I0 = 1.
Case 2: 0 0 0
I7 = I2 = 0.
I6 = I5 = I4 = I3 = I1= I0 =1
Case 3: 0 0 0
All 8 inputs are equal to 0.
Case 1:
Implement the circuit via simulation software and paste the result in here
Digital Logic Design Laboratory 6-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Make comment on results
Case 2:
Implement the circuit via simulation software and paste the result in here
Make comment on results
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Digital Logic Design Laboratory 7-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Case 3:
Implement the circuit via simulation software and paste the result in here
Make comment on results
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3. 2-to-4 Decoder - IC74HC139
Construct the circuit as below:
Figure 2 – Decoder 2-line-to-4-line IC 74HC139
- 4 outputs (Y0-Y3) are connected to LED display (Led 1-4).
- The data inputs (A, B) and control input (G) are connected to switches.
- Change the states of inputs to fulfill the truth table of IC 74HC139.
Digital Logic Design Laboratory 8-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Inputs
Outputs
Control Data
G B A Y0 Y1 Y2 Y3
0 0 0 0 1 1 1
0 0 1 1 0 1 1
0 1 0 1 1 0 1
0 1 1 1 1 1 0
1 X X 1 1 1 1
Implement the circuit via simulation software and paste the result in here
Briefly describe the operation of the IC
4. 3-TO-8 Decoder– IC 74HC138
Construct the circuit as below:
Digital Logic Design Laboratory 9-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Figure 3 – 3-to-8 Decoder/demultiplexer - IC 74HC138
- 8 outputs are connected by using LEDs.
- The inputs are controlled by switches.
- Observe the results and fulfill the truth table
INPUT OUTPUT
E3 E2 E1 C B A Y0 Y1 Y2 Y 3 Y4 Y 5 Y 6 Y7
1 0 0 0 0 0 0 1 1 1 1 1 1 1
1 0 0 0 0 1 1 0 1 1 1 1 1 1
1 0 0 0 1 0 1 1 0 1 1 1 1 1
1 0 0 0 1 1 1 1 1 0 1 1 1 1
1 0 0 1 0 0 1 1 1 1 0 1 1 1
1 0 0 1 0 1 1 1 1 1 1 0 1 1
1 0 0 1 1 0 1 1 1 1 1 1 0 1
1 0 0 1 1 1 1 1 1 1 1 1 1 0
0 X X X X X 1 1 1 1 1 1 1 1
X 1 X X X X 1 1 1 1 1 1 1 1
X X 1 X X X 1 1 1 1 1 1 1 1
Implement the circuit via simulation software and paste the result in here
Digital Logic Design Laboratory 10-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Briefly describe the operation of the IC
5. Design combinational circuits using decoders and OR gate
- Implement Boolean expression using IC 74HC138 & OR gate.
- The data inputs A, B, C are connected to switches.
- The control inputs are in suitable levels.
- Implement the circuit and verify the truth table
a. f =x ' y z ' + xz
Establish the truth table
Digital Logic Design Laboratory 11-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
x y z f
0 0 0 0
0 0 1 0
0 1 0 1
0 1 1 0
1 0 0 0
1 0 1 1
1 1 0 0
1 1 1 1
Implement the circuit via simulation software and paste the result in here
Verify the truth table and make comment on the results
Digital Logic Design Laboratory 12-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
b. f =x ' yz + x + y ' z ' = x’yz+xy’z’+xyz+xy’z+xyz’+x’y’z’
Establish the truth table
x y z f
0 0 0 1
0 0 1 0
0 1 0 0
0 1 1 1
1 0 0 1
1 0 1 1
1 1 0 1
1 1 1 1
Implement the circuit via simulation software and paste the result in here
Digital Logic Design Laboratory 13-14
INTERNATIONAL UNIVERSITY
SCHOOL OF ELECTRICAL ENGINEERING
Verify the truth table and make comment on the results
Digital Logic Design Laboratory 14-14
