An Introduction

1. Combinational Logic Circuits
Submitted To: Inam ul Haq
Submitted By: Group 7
Nazia Ali 1043
Nomara Naseer 1030
Mehwish Akhter 1034
Nitasha Masood 1036
University of Education, Okara Campus
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2. Table of Contents
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• Combinational logic
• Combinational logic diagram
• Difference bw combinational and sequential logic
• Adder
• Half Adder
• Full Adder
• Subtractor
• Half Subtractor
• Full Subtractor

3. Combinational Logic:
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In a Combinational Logic Circuit, the
output is dependant at all times on the
combination of its inputs. So if one of
its inputs condition changes state,
from 0-1 or 1-0, so too will the resulting
output as by default combinational
logic circuits have “no memory”,
“timing” or “feedback loops” within
their design.

4. Combinational logic Diagram:
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5. Continue:
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Combinational Logic Circuits are made up from
basic logic NAND, NOR or NOT gates that are
“combined” or connected together to produce
more complicated switching circuits. These logic
gates are the building blocks of Combinational
Logic Circuits. An example of a combinational
circuit is a decoder, which converts the binary
code data present at its input into a number of
different output lines, one at a time producing an
equivalent decimal code at its output.

6. Difference bw SequentialAnd
Combinational Logic:
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Unlike Sequential Logic Circuits whose
outputs are dependant on both their present
inputs and their previous output state giving
them some form of Memory, the outputs of
Combinational Logic Circuits are only
determined by the logical function of their
current input state, logic “0” or logic “1”, at
any given instant in time.

7. Adder:
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Adder is logic circuit which is used to add binary numbers.
Types Of Adder:
We divide adder into two types on the basis of their functions.
Half Adder:
Such a logic circuit which is used to add two binary
numbers at the same time. It consist of two inputs and two
outputs.
Full Adder:
Such a logic circuit which is used to add more then two
binary numbers at the same time. It consist of more then
two inputs and two outputs.

8. Truth Table of HalfAdderAnd Logic
Diagram:
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9. Truth Table of FullAdderAnd
Logic Diagram:
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10. Half Subtractor:
Such a logic circuit which is used to subtract two binary
numbers is know as half subtractor. It consist of two inputs
and two outputs.
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11. Full Subtractor:
Such a logic circuit which is used to subtract three binary
numbers is know as full subtractor. It consist of three
inputs and two outputs.
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