Q) Logic circuits gates.

A logic gates are an electronic circuit that are designed by using electrical components
like diodes, transistors, resistors, and more. It is used to perform logical operations based on the
inputs provided to it and gives a logical output that can be either high(1) or low(0). The operation
of logic gates is based on Boolean algebra or mathematics. Logic gates find their uses in our
day-to-day lives, such as in the architecture of our telephones, laptops, tablets and memory
devices.
Types of Logic Gates
Logic gates can be broadly classified into three main categories :
AND GATE
An AND gate is used to perform logical Multiplication of binary input. The Output state of the
AND gate will be high (1) if both the input is high (1), else the output state will be low(0) if any
of the input is low (0).
The Boolean Expression or logic for the AND gate is the logical multiplication of inputs denoted
by a full stop or single dot as :
A. B=X
The value of X will be True when both the inputs will be True.
Two Input AND Gate
Properties of AND Gate
The following are two main properties of the AND gate:
1. AND gate can accept two or more than two input values at a time.
2. When all of the inputs are logic 1, the output of this gate is logic 1.
OR GATE
OR GATE is most widely used digital logic circuit. The output state of OR gate will be high i.e.,
(1) if any of the input state is high or 1, else output state will be low i.e., 0.
The Boolean Expression for the OR gate is the logical addition of inputs denoted by plus sign
(+) as
X= A+B
The value of X will be high(true) when one of the inputs is set to high (true).
Two Input OR Gate
Properties of OR Gate
An OR gate have the following two properties:
1. It can have two or more input lines at a time.
2. When all of the inputs to the OR gate are low or logic 0, the output of it is low or logic 0.

NOT GATE
In digital electronics, the NOT gate is one of the basic Logic Gate having only a single input and
a single output. It is also known as inverter or inverting buffer. When the input signal is "low"
the output signal is "high" and vice-versa.
The Boolean expression of NOT Gate is as follows
Y = Ā or
Y = A’
the value of Y will be high when A will be low.
NOT Gate
Properties of NOT Gate
 The output of a NOT gate is complemented or inverse of the input applied to it.
 NOT gate takes only one output.

NOR GATE
The NOR gate is the type of universal logic gate. It takes two or more inputs and gives only one
output. The output state of the NOR gate will be high (1) when all the inputs are low
(0). NOR gate returns the complement result of the OR gate. It is basically a combination of two
basic logic gates i.e., OR gate and NOT gate.
The Boolean expression of NOR gate is as follows:
If A and B are considered as two inputs, and O as output, then the expression for a two input
NOR gate will be
O = (A + B)’
The value of O will be true when all of its inputs are set to 0.
Two Input NOR Gate
Properties of NOR Gate
The following are two important properties of NOR gate:
1. A NOR gate can have two or more inputs and gives an output.
2. A NOR gate gives a high or logic 1 output only when it's all inputs are low or logic 0.

NAND GATE
The NAND Gate is another type of Universal logic gate. The NAND gate or "Not AND" is the
combination of two basic logic gates AND gate and the NOT gate connected in series. It takes
two or more inputs and gives only one output. The output of the NAND gate will give result high
(1) when either of its input is high (1) or both of its input are low (0). In simple, it performs the
inverted operation of AND gate.
The Boolean Expression of NAND Gate is as follows
Say we have two inputs, A and B and the output is called X, then the expression is
X = (A. B)’
Two Input NAND Gate
Properties of NAND Gate
The following are the two key properties of NAND Gate
 NAND gate can take two or more inputs at a time and produces one output based on the
combination of inputs applied.
 NAND gate produces a low or logic 0 output only when its all inputs are high or logic 1.
XOR GATE
In digital electronics, there is a specially designed logic gate named, XOR gate, which is used in
digital circuits to perform modulo sum. It is also referred to as Exclusive OR gate or Ex-OR
gate. it is used extensively in arithmetic logic circuits., logic comparators and error detection
circuits. The XOR gate can take only two inputs at a time and give an output. The output of the
XOR gate is high (1) only when its two inputs are dissimilar i.e., if one of them is low (0) then
other one will be high (1).
Say we have two inputs, A and B and the output is called X, then the expression is
The Boolean expression of XOR Gate is as follows
X = A’B + AB’
XOR Gate
Properties of XOR Gate
The following two are the main properties of the XOR gate:
 It can accept only two inputs at a time. There is nothing like a three or more input XOR gate.
 The output of the XOR gate is logic 1 or high, when its inputs are dissimilar.

XNOR GATE
The XNOR is the combination of XOR gate and NOT gate. The output of the XNOR gate is
high(1) when both the inputs are high (1) or low(0). In other words, the output of the XNOR
gate is high(1) when both the inputs are the same. the XNOR gate can sometimes be called as
Equivalence gate. In simple words, The XNOR gate is the complement of the XOR gate.
The following is the Boolean expression of the XNOR gate,
Y=A⊙B
Here, A and B are the input variables and Y is the output variable.
This expression can also be written as follows,
Y = AB + A’B’
We can also express the operation of an XNOR gate using XOR gate logic as follows:
Y = (A ⊕ B)’
XNOR Gate
Properties of XNOR Gate
The following are two key properties of XNOR gate:
 XNOR gate takes only two inputs and produces one output.
 The output of the XNOR gate is high or logic 1 only when it has similar inputs.

Q) Classification of computer according to size and functions.

Computers come in a wide variety of forms and serve countless purposes. They can range from
tiny embedded systems to massive supercomputers, each designed to perform specific tasks. By
organizing them based on factors such as size, function, and intended use, we can better
understand the unique roles they play in our daily lives and industries.
Classification of Computers According to Size

Computers can be categorised into four types based on size and configuration:

1) Supercomputers
Supercomputers are the most efficient in terms of data processing and performance. They are used
for research, space exploration, seismic research, and nuclear testing.
Their key features include the following:

a) Use of Artificial Intelligence (AI)

b) Fastest and most powerful

c) Very costly and large

d) Employed by manufacturing companies

e) Rapid information processing

2) Mainframe Computers
Mainframe computers, though less efficient than supercomputers, are still very expensive. They
are used by large corporations and government organisations for daily operations, storing and
analysing large amounts of data.
Their core attributes are as follows:

a) Enormous memory

b) Capable of running multiple operating systems

c) Numerous CPUs with powerful processing speeds

d) Use of Tightly Coupled Clustering Technology

3) Minicomputers
Minicomputers, or midrange computers, are used by small businesses and industries. They support
multiple users and are slower than mainframes.

A few of their essential characteristics include the following:

a) Smaller and less costly than mainframes or supercomputers

b) Capable of multitasking

c) Used by small businesses

4) Microcomputers
Microcomputers, or Personal Computers (PCs), are smaller and more affordable. They include a
Central Processing Unit (CPU), microprocessor, Read-only Memory (ROM), Random Access
Memory (RAM), Input/Output (I/O) ports, and a bus system.

Some of their essential features are mentioned here:

a) Extensive personal use

b) Smaller and less expensive

c) Limited computational capacity

d) Easy to use
Classification of Computers According to Purpose

Computers can also be classified based on the tasks they perform:

1) General Purpose Computers

2) Specific Purpose Computers