3. Contents:
1. What are Logic Gates
2. Types Of Basic Logic
Gates
3. AND Gate
4. OR Gate
5. NOT Gate
6. Combining Basic Logic
Gates
7. Applications
4. What are Logic Gates?
Logic gates are fundamental building blocks in
digital circuitry and computer systems.
They are electronic devices that perform basic
logical operations on binary inputs, which
consist of 0s and 1s.These gates are the
building blocks of digital circuits and are used
to process and manipulate binary information.
They are interconnected in specific ways to
create more complex circuits that can perform a
wide range of logical and arithmetic operations,
forming the basis for the binary digital
computation used in modern electronic
systems.
5. Types of Basic Logic
Gates
1. AND Gate
2. OR Gate
3. NOT Gate
6. AND Gate
AND gate is the fundamental logic gate that executes the
logical multiplication of binary input. The AND operation is
carried out in the same way as standard multiplications of 1s
and 0s. An AND gate is a logic circuit that performs AND
operations on the input of the circuit. When all the inputs are
1, the AND Gate outputs 1, otherwise it outputs 0. A dot (.)
denotes the AND operation.
Say we have two inputs, A and B and the output is called X,
then the expression is:
X = (A . B)
7. OR Gate
The OR gate is a mostly used digital logic circuit. The output state
of the OR gate will always be low when both of the inputs states is
low. Simply, if any input value in the OR gate is set to 1, then it
will always return high-level output(1).The logic or Boolean
expression for the OR gate is the logical addition of inputs
denoted by plus sign(+) . The value of Y will be true when one of
the inputs is set to true.
Say we have two inputs, A and B and the output is called X, then
the expression is:
Y = (A + B)
8. NOT Gate
The NOT gate is the most basic logic gate of all other logic
gates. NOT gate is also known as an inverter or an
inverting Buffer. NOT gate only has one input and one
output. When the input signal is "Low", the output signal
is "High" and when the input signal is "High", the output is
"Low". The Boolean expression for the NOT gate is as
follows:
A'=Y
When A is not true, then Y is true
9. Combining Basic Logic Gates
These basic gates can be combined to form more
complicated circuits. Here are some of the examples :
1. NAND Gate: It is the combination of NOT and AND
gate. The logic or Boolean expression for the NAND
gate is the complement of logical multiplication of inputs
denoted by a full stop or a single dot as
(A.B)’=Y
2. NOR Gate: It is the combination of NOT and OR
gate. The logical or Boolean expression for the NOR
gate is the complement of logical multiplication of inputs
denoted by the plus sign as
(A+B)'=Y
Both of these gates are universal gates and can be used
as AND gates, OR gates and NOT gates.
Universa
lGates
10. Applications
• Logic gates form the basic building blocks of digital
computers. They are used to perform logical
operations and manipulate binary data.
• Logic gates are used to perform arithmetic
operations such as addition, subtraction,
multiplication, and division in digital circuits.
• Flip-flops and other memory elements in computers
are constructed using logic gates. These elements
are crucial for storing and retrieving information in
digital systems.
• Logic gates play a vital role in the control units of
digital systems. They are used to implement control
logic that manages the flow of data within a system.