There are three main ways to represent gates and circuits: logic diagrams using symbolic drawings, truth tables listing all input-output combinations, and Boolean expressions using algebraic notation. The document then describes the seven basic logic gates - NOT, AND, OR, XOR, NAND, NOR, and XNOR - showing their truth tables, symbols, and examples of practical applications. It explains that NOT, AND and OR are the fundamental gates, while NAND and NOR are considered "universal gates" since all others can be constructed from them.

1. REPRESENTATION OF GATES
1. Logic diagrams
2. Truth tables
3. Boolean expressions
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2. Representation of Gates
• There are three different, but equally
powerful, notational methods
for describing the behavior of gates
and circuits
– Logic diagrams
– Truth tables
– Boolean expressions
2

3. 1- Logic diagram
• Logic diagram: a graphical representation
of a circuit
– Each type of gate is represented by a specific
graphical symbol
3

4. 2- Truth table
• Truth table: defines the function of a gate
by listing all possible input combinations
that the gate could encounter, and the
corresponding output
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5. 3- Boolean algebra
• Boolean algebra: expressions in this
algebraic notation are an elegant and
powerful way to demonstrate the activity of
electrical circuits
 AND is denoted by a dot (.)
OR is denoted by a plus (+).
NOT is denoted by a single quote mark (')
after the variable or an overbar ( ¯ ).
XOR is denoted by
5

6. Note
The statement:
1 + 1 = 2 (read “one plus one equals two”) is
not the same as 1 + 1 = 1 (read “1 or 1
equals 1”).
1.1 = 1 ( read 1 AND 1 equals 1 )
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7. TYPES OF GATES
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8. Types of Gates
• Let’s examine the processing of the following
seven types of gates
– NOT
– AND
– OR
– XOR
– NAND
– NOR
– XNOR
Three Basic Gate Functions
Additional Gate Functions
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9.  Three Basic Gate Functions
 Using these three gates we can design any
logic circuit.
 Additional Gate Functions
 We will define four additional gates which aid
circuit design.
Types of Gates
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10. THREE BASIC GATE FUNCTIONS
1. NOT
2. AND
3. OR
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11. NOT Gate Representation
• A NOT gate accepts one input value
and produces one output value
Figure 4.1 Various representations of a NOT gate
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
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12. What NOT Gate Means
• By definition, if the input value for a NOT
gate is 0, the output value is 1, and if the
input value is 1, the output is 0
• A NOT gate is sometimes referred to as
an inverter because it inverts the input
value
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13. Example of NOT Gate
e.g. I turn on the heating if it is NOT hot
if A = hot and Y = Heating on then:
where the bar represents logical NOT.
A
Y 
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14. Practical Application of “Not”
Logic Gate
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15. AND Gate Representation
• An AND gate accepts two input signals
• If the two input values for an AND gate are
both 1, the output is 1; otherwise, the
output is 0
Figure 4.2 Various representations of an AND gate
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
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16. Example of AND gate
e.g. I get up early if I have lectures AND it is a weekday
he said if A = lecture B = weekday and Y = get up early
then he said you can write:
where the dot represents logical AND.
Thus ,
If 1 represents TRUE and 0 represents FALSE
then the function can be defined in a truth table.
B
A
Y 

Logic Gates 16

17. How AND Gate Work
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18. Practical Application of “AND”
Logic Gate
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19. OR Gate Representation
• If the two input values are both 0, the
output value is 0; otherwise, the output is 1
Figure 4.3 Various representations of a OR gate
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
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20. How OR Gate Work
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21. Example of OR Gate
e.g. I turn on my headlights if it is dark OR it is raining
if A = dark B = raining and Y = headlights on then:
where the + sign represents logical OR.
B
A
Y 

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22. Practical Application of “OR”
Logic Gate
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23. ADDITIONAL GATES FUNCTIONS
1. XOR
2. NAND
3. NOR
4. XNOR 23

24. What XOR Gate Means
• XOR, or exclusive OR, gate
– An XOR gate produces 0 if its two inputs are
the same, and a 1 otherwise
– Note the difference between the XOR gate
and the OR gate; they differ only in one
input situation
 When both input signals are 1, the OR gate
produces a 1 and the XOR produces a 0
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25. XOR Gate Representation
Figure 4.4 Various representations of an XOR gate
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
25

26. NAND and NOR Gates
• The NAND and NOR gates are essentially the
opposite of the AND and OR gates, respectively
Figure 4.5 Various representations
of a NAND gate
Figure 4.6 Various representations
of a NOR gate
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
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27. How NAND Gate Work
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28. How NOR Gate Work
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29. XNOR
The XNOR gate is essentially the opposite of the XOR.
To illustrate how it works visually .. Check this link: https://logic.ly/lessons/
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30. Conclusion
• Logic Gate is an electronic circuit which
receive one or more than one input and deliver
single output.
• There are seven logic gates. NOT , OR , AND
are the basic logic gates. NOR , NAND, XOR ,
NXOR are the additional logic gates.
• A NOT gate inverts its single input value.
• An AND gate produces 1 if both input values
are 1.
• An OR gate produces 1 if one or the other or
both input values are 1. 30

31. Conclusion
• An XOR gate produces 1 if one or the other
(but not both) input values are 1.
• A NAND gate produces the opposite results
of an AND gate.
• A NOR gate produces the opposite results of
an OR gate.
• A XNOR gate produces the opposite results
of an XOR gate.
• NAND and NOR gates are referred to as
universal gates as the three basic gates can
be constructed using either one of the two. 31

32. Conclusion
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33. Conclusion
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