There are four main categories of computers based on their size and capabilities: mainframe computers, mini computers, micro computers, and super computers. Mainframe computers are the largest, can process vast amounts of data, but require trained operators. Micro computers are the smallest, most affordable, and user-friendly, commonly used as personal computers. There are also three basic types of computers based on how they process data: analog computers which handle continuous data like temperature, digital computers which operate using binary digits, and hybrid computers which combine aspects of analog and digital to process both continuous and discrete data.

1. LecturerSalmanKhan,AWKUM
CLASSIFICATION OF COMPUTERS
Computer is an electronic device to perform mathematical and logical
calculations. Computers can be classified in various ways depending upon
its size, memory capacity; processing speed etc. computers are classified
in four categories
1. Mainframe Computers
2. Mini Computers
3. Micro Computers
4. Super Computers
Mainframe Computers
1. They are big computer systems sensitive to temperature, humidity,
dust etc.
2. Qualified & trained operators are required to operate them.
3. They have wide range of peripherals attached.
4. They have large storage capacity.
5. They can use wide variety of software’s.
6. They are not user friendly.
7. They can be used for more mathematical calculations.
8. They are installed in large commercial places or government
organization
Mini Computers
1. They have less memory & storage capacity than mainframe computers.
2. They offer limited range of peripherals.
3. Limited range of software’s can be used by them.
4. The end users can directly operate it.
5. They are not very sensitive to the external environment and hence are
more generalized.

2. LecturerSalmanKhan,AWKUM
6. They are used for data processing.
Micro Computers
1. They brought revolution in the history of computers.
2. They are also known as Personal Computers.
3. They are cheap and user friendly.
4. The main components are Monitor, CPU, Keyboard, Mouse, Speakers,
Modem and Printer.
5. They are having limited peripherals attached to them.
6. This type of computers can use wide range of software’s.
7. They are used as desktops either in offices or even homes.
8. Their operation can be easily learnt
9. Playing games & watching movies
10. Most popular micro computer’s processing chip manufacturing
company is Intel
Super Computers
1. They are huge computers installed in space centers, nuclear power
stations etc.
2. They are used for performing complex mathematic calculations.
3. Only scientists and mathematicians can operate them.
4. They are having huge memories & tremendous processing speed.
5. They are used for weather forecasting, animation graphics etc
Basic kinds ofcomputer
There are three basic kinds of computers. This is based on the hardware
structure and the way physical quantities are represented in a computer.
The following are the three types.

3. LecturerSalmanKhan,AWKUM
Analog Computers
Analog computers are used to process analog data. Analog data is of
continuous nature and which is not discrete or separate. Such type of
data includes temperature, pressure, speed weight, voltage, depth etc.
These quantities are continuous and having an infinite variety of values.
It measures continuous changes in some physical quantity e.g. The
Speedometer of a car measures speed, the change of temperature is
measured by a Thermometer, the weight is measured by Weights
machine. These computers are ideal in situations where data can be
accepted directly from measuring instrument without having to convert it
into numbers or codes.
Analog computers are the first computers being developed and provided
the basis for the development of the modern digital computers. Analog
computers are widely used for certain specialized engineering and
scientific applications, for calculation and measurement of analog
quantities. They are frequently used to control process such as those
found in oil refinery where flow and temperature measurements are
important. They are used for example in paper making and in chemical
industry. Analog computers do not require any storage capability because
they measure and compare quantities in a single operation. Output from
an analog computer is generally in the form of readings on a series of dial
(Speedometer of a car) or a graph on strip chart.
Digital Computers
A Digital Computer, as its name implies, works with digits to represent
numerals, letters or other special symbols. Digital Computers operate on
inputs which are ON-OFF type and its output is also in the form of ON-OFF
signal. Normally, an ON is represented by a 1 and an OFF is represented
by a 0. So we can say that digital computers process information which is

4. LecturerSalmanKhan,AWKUM
based on the presence or the absence of an electrical charge or we prefer
to say a binary 1 or 0.
A digital computer can be used to process numeric as well as non-numeric
data. It can perform arithmetic operations like addition, subtraction,
multiplication and division and also logical operations. Most of the
computers available today are digital computers. The most common
examples of digital computers are accounting machines and calculators.
The results of digital computers are more accurate than the results of
analog computers. Analog computers are faster than digital. Analog
computers lack memory whereas digital computers store information. We
can say that digital computers count and analog computers measures.
HybridComputers
A hybrid is a combination of digital and analog computers. It combines
the best features of both types of computers, i-e. It has the speed of
analog computer and the memory and accuracy of digital computer.
Hybrid computers are used mainly in specialized applications where both
kinds of data need to be processed. Therefore, they help the user, to
process both continuous and discrete data. For example a petrol pump
contains a processor that converts fuel flow measurements into quantity
and price values. In hospital Intensive Care Unit (ICU), an analog device
is used which measures patient's blood pressure and temperature etc,
which are then converted and displayed in the form of digits. Hybrid
computers for example are used for scientific calculations, in defense and
radar systems.