2023.Spring.Lab3.Experiment (1)
The University of Texas at Dallas
Department of Computer Science
CS 4141: Digital Systems La
Experiment #3 – The Digital Adder Circuit
CS 4141 Laboratory 3, EXPERIMENT
Introduction
In the last two laboratory exercises, we studied logic gates and basic combinational
logic circuits. In this experiment is about the adder circuit. Arithmetic circuits like digital
adders are widely used in sequential circuits, such as microprocessors. The adder
circuit is one part of an Arithmetic Logic Unit (ALU), the heart of processor. Today’s lab
concerns the combinational logic of digital addition.
Objective
The purpose of this lab is to become familiar with the functionality of digital adder circuits. The
74LS283 4-bit full adder or similar IC will be used to get the feel of how adder ICs operate.
Turn-In Check List
The laboratory has two items to grade.
1. Demonstrate the working circuits to the Lab Instructor (40 points)
2. Put supplies away co
ectly sorting and returning all chips. (10 points)
3. Produce the Post-Lab Report (30 points)
Equipment List
The following components are required for this experiment:
• IDL-800a Digital Lab Station (“
eadboard” unit with test equipment built-in power supply)
• Full Adder (Such as SN74LS283)
• AND gate IC Chip (Such as SN74LS08)
• OR gate IC Chip (Such as SN74LS32)
• XOR gate IC Chip (Such as SN74LS86)
• Breadboard wires (jumpers)
1
Chandrahas Nanduri
Chandrahas Nanduri
The University of Texas at Dallas
Department of Computer Science
CS 4141: Digital Systems La
Experimental Procedure
Part 1. 4-bit Addition using an IC chip such as 74LS283
• Read the Manual for 74283 which is on the course webpage. Make the connections
as shown and get the 4-bit full adder working.
• Try different inputs for input A and input B and check the outputs.
• For the Post-Lab report include
o a truth table containing 10 different combinations of input A and input B,
including the Cin and the Cout
o a circuit diagram (not logic diagram) naming the adder chip and all its
connections
Part 2. 4-bit Subtraction using an IC chip such as 74LS283
• Review the pre-lab and implement a 2-bit adde
subtractor circuit
• Observe the output. The output is in 2’s complement form for 2 bits. Remember, 2’s
compliment flips all the bits and adds 1.
• For the Post-Lab report include:
o a truth table containing 10 different combinations of input A and input B (5
additions and 5 subtractions)
o a circuit diagram (not logic diagram) of the adde
subtractor circuit, naming
the adder chip, and any additional IC’s.
Input A Input B Cin Binary Output Binary Integer 2’s Compliment Intege
XXXXXXXXXX
XXXXXXXXXX
XXXXXXXXXX -2
XXXXXXXXXX -1
2
Chandrahas Nanduri
Chandrahas Nanduri
The University of Texas at Dallas
Department of Computer Science
CS 4141: Digital Systems La
Part 3. Construct a Binary Coded Decimal (BCD) adder using the 4-bit binary full adders
• Review the pre-lab and implement a BCD adder circuit
• In a binary coded decimal (BCD) system, 4 bits are used to represent a decimal digit
from 0 to 9.
Since each decimal digit cannot exceed 9 for this part of the lab, the maximum BCD
sum can be 19 = XXXXXXXXXXCin)
• For the Post-Lab report include:
o A truth table that shows the decimal value from 0 to 19, the binary value from
0 to 19, and the BCD value from 0 to 19.
o a circuit diagram (not logic diagram) of the BCD adder circuit, naming the
adder chip, and any additional IC’s.
Equipment Disassembly: The experimental procedure is complete. Please
disassemble the circuit wiring, replace in the wires and replace all IC chips in their
proper boxes. Make sure that your work area is clean.
For the Post-Lab Report (30 points)
• First, include your name, section, and date of the experiment.
• Second, include the title “Experiment 3 Post-Lab”
• If you were working with a partner on a lab station,
o Then include your partners’ name
• For the experiment
o Part 1: Results of 10 4-bit Additions (5 points)
o Part 1: Circuit Diagram of the IC chip (5 points)
o Part 2: Results of 5 2-bit additions, and 5 2-bit subtractions (5 points)
o Part 2: Circuit Diagram of the 2-bit Adde
Subtractor (5 points)
o Part 3: Truth Table of 0 through 19 for the BCD Adder (5 points)
o Part 3: Circuit Diagram of the BCD Adder (5 points)
• Citations: If you are using software to draw your diagrams, identify the software.
Decimal Value Binary Value BCD Value
XXXXXXXXXX
XXXXXXXXXX0001
XXXXXXXXXX0011
XXXXXXXXXX0101
XXXXXXXXXX0111
3
Chandrahas Nanduri
The University of Texas at Dallas
Department of Computer Science
CS 4141: Digital Systems La
4
Experiment #3 – The Digital Adder Circuit
CS 4141 Laboratory 3, EXPERIMENT
Introduction
Objective
Turn-In Check List
Experimental Procedure
Part 1. 4-bit Addition using an IC chip such as 74LS283
Part 2. 4-bit Subtraction using an IC chip such as 74LS283
For the Post-Lab Report (30 points)
The circuit diagram and logic symbol are on the left and right, respectively. You can read more
information about this chip in Adder-74283.pdf.
157 Binary Number 2" Binary Numbe
LLL PELs
As Ay Ay Ag Bs; B, Bi Bo
Cou 4-bit Full Adder Cin
Ss S; Si So
Su NEN
Sum
Fig. 1. Logic Symbol for a 4-bit Full Adde
Vee B: Az Sz As Bs Ss Cout
XXXXXXXXXX" 10 9