Computers
are classified based on their capacities and uses. The major classification of
computer are
·
On the basis of work
·
On the basis of size
·
On the basis of brand
·
On the basis of model
Brand
|
Size
|
Work
|
Model
|
XT
AT
PS/2
|
IBM PC
IBM Compatible
Apple/Macintosh
|
Micro
Mini
Mainframe
Super
|
Analog
Digital
Hybrid
|
Classification of
Computers
|
On the
basis of Work
Analog Computer: -Computer
is one which operates on continuous data usually a physical quantity such as temperature,
electrical, mechanical, hydraulic, pressure etc. It is a special purpose
computer, dedicated to a single task. It is widely used in scientific and
industrial application. Analog computers recognize data as continuous measure
of physical property (voltmeter, pressure, temperature).
Example: Plesley, Seismography,
speedometer, Thermometer, voltmeter, pressure gauge, odometer, ammeter,
barometer, lactometer etc.
Digital Computer:
A digital computer is an electronic computing machine that uses the binary
digits (bits) 0 and 1 to represent all forms of information in digital form.
These are high speed programmable electronic device that perform mathematical
calculations, compares values and store results. They recognize data by
counting discrete signal representing either high or low. In digital computer,
even letters, words and whole text are represented digitally. It is a general
purpose device, dedicated to a multiple task.
Example IBM PC, Apple/Macintosh computer
Difference
between Analog and Digital computer
Analog
Computer
|
Digital
Computer
|
1. Analog
computer measures the continuous physical variations such as pressure,
temperature, voltage etc.
|
1. Digital
computer processes discrete data such as number, letters etc.
|
2. It generates
analog signals
|
2. It
generates digital signal
|
3. It has
very low accuracy
|
3. It has
high accuracy
|
4. It has
high cost
|
4. It has
low cost.
|
5. It is used
for special purpose
|
5. It is used
for general purpose
|
6. Re-programmed
is not possible
|
6. Re-programmed
can be possible
|
7. It
is based on similarity measurement
principle
|
7. It is
based on counting principle
|
8. It is faster
than digital computer
|
8. It is slower
than analog computer
|
9. It has
no or limited storage capacity
|
9. It has
high storage capacity
|
10. It does
singe purpose job
|
10. It does
multipurpose job
|
11. Is is
stored in the form of wave signal
|
11. It is
stored in the form of binary bit
|
12. Analog
signal processing can be done in real time
and consumes less bandwidth.
|
12. There
is no guarantee that digital signal processing can be done in real time and consumes
more bandwidth to carry out same information.
|
13. E.g.
Speedometer, Seismograph, Plesley
|
13. E.g.
IBM PC, IBM Compatible,, Apple/Macintosh
|
Hybrid Computer:
Computer that contains the features of both analog computers and digital
computer that are capable of inputting and outputting in both analog and
digital signal. Example FMC (Flight Management Computer), EICS, aero planes,
jet planes, industries, ICU (Intensive Care Unit) in hospital etc.
Characteristic
of hybrid computer: -
i)
It combines the best qualities of analog
and digital computer.
ii) It
can process both continuous and discrete data
iii) It
can convert one type of data into another.
iv) These
computers are mostly used in areophane, hospital, industries etc.
v)
It is expensive.
vi) These
computes are mostly used in hospital to measure heard beat of patient
Classification on the basis of size:
- computers on the basis of size or volume are classified as following types
Super computer:
-Super computer are the largest, fastest and most expensive computers. The have
lager memory capacity and very high processing speed. The are 64-bit system with
100 MIPS (Millions of Instruction per second) speed and 8 MB storage capacity.
They are used for solving very large and complex problems within a Nanoseconds.
It is multiuser, multiprocessor large computer with a very high efficiency and storing
capacity. Example are CRAY-XMP/14, CDC-205, CYBER 205, ETA 10 etc.
Application of supercomputer
Aerospace
industry:
- to simulate airflow around an aircraft at different speed and altitude.
Automobile
industry: -
design of an automobile and to do crash simulation.
Structural
mechanic:
to solve structural engineering problems to ensure safety, reliability and cost
effectiveness.
Petroleum
industry: -
to analyze data about petroleum product inside the earth.
Weapons
research
Encrypting and
decrypting sensitive intelligence information.
Scientific
computing and research
Weather
forecasting: Meteorological centers use supercomputer for weather
forecasting.
Biomedical
research- atomic nuclear and plasma analysis, to study the structure of
viruses.
Mainframe computer: -
Mainframe computer are the computers with large storage capacities and very high
speed of processing that support large amount of terminals for simulations use
by number of users. Mainframe computer will have a very powerful processor,
large amount of main memory and huge backing storage capacity. They are used in
banking, airline, railways, educational institution, insurance companies etc.
They are also called Enterprise Server. Example IBM1401, ICL 2959/10, IBM S/390
etc.
Characteristic
1. They are
very large in size with large storage capacity and high processing speed.
2. They
support large number of terminals approximately 100.
3. It is
general purpose computer.
4. Consist
of multiple processor, GB of memory and TB of storage,
5. They can
run multiple operating system. Hence they are called virtual machine.
Application:
- used for process large amount of data at very high speed such as in
bank/insurance companies, hospitals, railways,
Used to
controlling node in WAN
Used to
manage large centralized database.
Minicomputer:-Minicomputer
is a general purpose computer which is comparatively small and less expensive
than a mainframe computer. It has slowest operation speed, smaller vacuum
storage, limited hardware and lesser memory capacity compared to a mainframe
computer. They are used by small business and firms. Minicomputer are also
called midrange system or workstations. Example IBM, HP-9000, PDA-II etc.
Characteristics
·
There are medium sized computers.
·
They support small number
of terminals approximately 50.
·
They are general purpose
computer.
·
They can process more
data can can support more I/O devices.
·
They are less powerful
than mainframe computers but more powerful than microcomputers. Hence they are
called midrange computers.
·
They are used in business
as a centralized computer or as an internet server.
·
They are less expensive
than mainframe computer and more expensive than microcomputer.
·
They are used in medium
sized organizations.
Microcomputer:
- A microcomputer is the smallest general purpose
processing system based on microprocessor or chip. It consists of a CPU in a
single which supports storage of a much smaller scale like hard disk or floppy
disk, it can be used by a single person at a time. Microcomputer are also
called personal computer. the peripheral device used in microcomputer are
keyboard, magnetic disk, monitor, printer, mouse, etc.
Microcomputer are
used in wide range like general purpose calculation, teaching, industrial
control, office automation and business communication. Example PC of IBM,
Apple/Macintosh
Characteristics
of microcomputers are
I.
They are smallest in size.
II.
They are based on
microchips.
III.
Though they are small in
size, some microcomputers has high storage and processing capacity.
IV.
It supports may higher
level language.
V.
It supports multimedia
VI.
It supports multimedia.
VII.
It supports graphic, 3D
graphic and games.
VIII.
It supports networking.
IX.
It supports new features
of input and output devices
X.
It supports different
types of operating system like as GUI and CUI.
Difference between Mini and
microcomputers.
Mini
Computer
|
Micro
computer
|
They
are more powerful than micro computers
|
They
are less powerful than mini computer
|
They
are comparatively more expensive
|
They
are comparatively cheaper
|
They
are bigger in size so that nearly 50 terminals can work
|
They
are smaller in size and can work only single
terminal;
|
They
are not general purpose
|
They are
general purpose computers.
|
Example
IBM, HP-9000, PDA-II etc.
|
Example
: PC of IBM, Apple/Macintosh
|
On the
basis of brand
IBM PC
(IBM Personal Computer): - The computer developed by International
Business machine company (IBM) are called IBM PCs. IBM company was developed in
1924. In 1945, IBM company stated manufacturing digital computer. IBM computer
are more reliable, durable and have better quality. It was specifically design
for professional and scientific problem solvers.
IBM Compatible Computer: -
IBM compatible computers are developed by other than IBM companies using the
technology of IBM PC. They have the same functional and operational characteristic
of IBM PC. All the program used in IBM are compatible with IBM compatible so
they are called as duplicate of IBM.
They are cheap, easily available, Example Compaq, NEC (Nippon
electronic,) ALR (Advance Logic Research), AST, SCAN, IT 2000 etc.
Apple/ Macintosh Computer: -
Apple computers are developed by Apple Corporation which was established in
late 1970s, in the USA. Apple Corporation developed a most popular
microcomputer named Macintosh. This computer is mainly used for desktop
publishing work. Apple cost are costlier the IBM computer. They are available
in different capacity, cost and sizes.
Different
between IBM PC and IBM Compatible computers
IBM PC
|
IBM
Compatible
|
1. They
are original and banded computes manufactures by IBM company itself
|
1. They are
duplicated and assembled computers developed by local company with the permission
of IBM company
|
2. They
are more expensive
|
2. They are
cheaper then IBM PC
|
3. They
are comparatively stronger
|
3. They
are comparatively less strong
|
4. They
use original and genuine software
|
4. They
use genuine and pirated software both
|
5. They
are more reliable then IBM compatible
|
5. They
are less reliable than IM PCs.
|
6. It was
specially designed for professionals and scientific problem solvers.
|
6. It was
designed for general user and their parts are easily available in market.
|
Difference
between IBM PC and Apple Macintosh
IBM PC
|
Apple/Macintosh
|
1. These
computers use both GUI and CUI programs
|
1.
These computers use only GUI program
|
2. They
are manufactures by IBM company USA
|
2.
They are manufactured by apple
corporation USA
|
3. Mouse
or pointing input device is optional to these computers
|
3.
Mouse or pointing input device is compulsion
to the computers
|
4. In IBM
PC the VDU and CPU are separated
|
4.
In apple ,/Macintosh computes the VDU
and CPU are attaches together.
|
5. In IBM
PCs, the mouse is connected to CPU
|
5.
In Apple/Macintosh computers, the mouse is
connected to keyboard
|
6. They
are comparatively less expensive
|
6.
They are comparatively more expensive.
|
Personal Computer:
- A personal computer is a single user oriented and general purpose micro
computer processing system that can execute the program instruction to perform
a wide variety of task. A personal
computer contains a monitor, keyboard; mouse etc. high level language can be
used in a personal computer. Operating system such as Microsoft Windows, Linux
and UNIX are used in thus type of computer system.
Types of Personal Computers
Desktop computer:
Desktop computers are the single user personal computers that can be placed on
the desktop. Desktop computer contains primary memory (RAM, ROM) and secondary
storage like hard disk, magnetic tape, CD/DVD ROM etc. peripheral devices such
as monitor, keyboard, mouse etc are attached with it. It is used for desktop
publishing, graphics, data entry, entertainment etc.
Laptop computer: Laptops computer are portable computer and
the size of a laptop computer can easily fir in a briefcase. Laptop computers
are very light in weight, small in size and flat design. A laptop contains attached
keyboard, a flat LCD display, a touch pad, CD/DVD derive etc. Laptop computer
normally runs Microsoft Windows, Linux, and UNIX etc.
Handheld computer:
A hand held computer is a device whose size, weight and design are such that it
can be used comfortably by holding in hand. It is also known as palmtop because
it can be kept on palm and operated. Some popular and held computers are
tablets PC, PDA/Pocket PC and smart phones.
On the Basis of Model
XT Computer (Extended technology): The
computer which uses 8086 or 8088 microprocessor and having processing speed
4.77 MHZ. It is comparatively slower and less flexible than other model. It
cannot support GUI based program and software.
AT computer: The
computer which uses 80286, 80386, 80846 or 80586 series of microprocessor is
known as AT computer. At computer are faster than XT computer. Its processing
speed and memory capacity is also larger than XT.
PS/2 (Personal System-2): - These
type of computer came in the market after 1990 manufactured by IBM company.
These models of computer are faster and efficient that AT modern and based on
refined architectural design.
Mobile Computing: It
is the process or method of using portable computing technology that allows to
use and access internet and other application services when we are on move.
Small and portable handheld computing devices and advanced mobile phone are
popularly used.
Mobile computing has three aspects mobile
communication, mobile hardware and mobile software. The first aspect addresses
communications issues in ad-hc and infrastructure networks as well as
communication properties, protocol, data format and concrete technologies. The
second aspect is on the hardware e.g. mobile devices or device computers. The
third aspect deals with the characteristics and requirements of mobile
applications. There are different types of mobile computing device such as personal
digital assistance(PDA), smart phone, blackberry phone, iPhone, internet tablets,
HSPDA (High Speed Packet Data Access) and other 3G mobile etc.