There are computers available having different sizes, shapes, weights, because of these differentiation the computers perform different types of jobs from one another, and therefor they are classified in four categories.
1. Super computers
2.
Mainframe Computers
3.
Mini Computers
4.
Micro Computers
SUPERCOMPUTERS
Supercomputers are the fastest and the most powerful computers and they are very expensive too. It was developed in
1980s. They are used to solve complicated scientific problems and process large amount of data. They can perform more than one trillions calculations per
second. They are consists of have large number of processors. So parallel
processing is done in this computer. Supercomputers are mainly used for:
- Weather forecasting.
- Nuclear energy research.
- Aircraft design.
- Automotive design.
- Online banking.
- To control industrial units.
The
examples of supercomputers are CRAY-1, CRAY-2, Control Data CYBER 205 and ETA
A-10 etc.
MAINFRAME COMPUTERS
Mainframe
computers are large computers but as compared to supercomputers they are small. These are also very expensive. The mainframe
computers are very expensive because of its care, they require large clean rooms with
air-conditioner, because they generate heat. They have multiple processors in it. Large mainframe systems can handle the input and output
requirements of several thousand of users. For example, IBM, S/390 mainframe
can support 50,000 users simultaneously.
The
mainframe computers are specially used to serve websites or Internet traffic. The
mainframe computers are used in large organizations such as Banks, Airlines and
Universities etc. where many people/ users are frequent using the data, which is usually organized in shape of databases. IBM is the
major manufacturer of mainframe computers. The examples of mainframes are IBM
S/390, Control Data CYBER 176 and Amdahl 580 etc.
MINI COMPUTERS
Comparatively these
are smaller in size, having lower processing speed and also have lower cost. These computers are known as minicomputers because of their small
size. The capabilities of a
minicomputer are between mainframe and personal computer.
Businessman, education sector and industries use minicomputers departments. Although some minicomputers are designed for a single user but
most are designed to handle multiple terminals. Minicomputers are basically used
as a servers in networking environment and handle hundreds of
personal computers. .
The
first minicomputer was introduced in the mid-1960s by Digital Equipment
Corporation (DEC). After this IBM Corporation (AS/400 computers) Data General
Corporation and Prime Computer also designed the mini computers.
MICROCOMPUTER
The microcomputers are also known as personal computer or simply PC. Microprocessors are used in these type of computers. These are very small in size and cost. The IBM’s first microcomputer was designed in 1981 and was named as IBM-PC. The most popular types of personal computers are the PC and the Apple.
The microcomputers are also known as personal computer or simply PC. Microprocessors are used in these type of computers. These are very small in size and cost. The IBM’s first microcomputer was designed in 1981 and was named as IBM-PC. The most popular types of personal computers are the PC and the Apple.
- Desktop PCs
- Tower PCs
A
desktop personal computer
is most popular model of personal computer. The system unit of the desktop
personal computer can lie flat on the table. In desktop personal
computer.
The tower personal computer is vertically placed on the desk of table. Both types of computers are used by users, there is no difference in speed and working of both, the only difference is the space they cover.
Microcomputers
are further divided into following categories.
- Laptop computer
- Workstation
- Network computer
- Handheld computer
LAPTOP COMPUTER
Laptop
computers or notebooks are small in size usually 85 x 11 inch. The
laptops are operated on a battery and it does not have to be
plugged ON continuously. The laptops are portable
and fully functional microcomputer. They are mostly used during traveling but now a days most of the users are switching to laptops from desktops computers.
The
memory and storage capacity of laptop computer is almost equivalent to the PC
or desktop computer.
WORKSTATIONS
Workstations
are special single user computers having the same features as personal computer
but have the processing speed equivalent to minicomputer or mainframe computer.
A workstation computer can be fitted on a desktop. Scientists, engineers, architects and graphic designers mostly use these computers.
Workstation
computers are expensive and powerful computers. These have advanced processors,
more RAM and storage capacity than personal computers. These are usually used
as single-user applications but these are used as servers on computer network
and web servers as well.
NETWORK COMPUTERS
Network
computers are also version of personal computers having less processing power,
memory and storage. These are specially designed as terminals for network
environment. Some types of network computers have no storage. The network
computers are designed for network, Internet or Intranet for data entry or to
access data on the network.
The network computers depend upon the network’s
server for data storage and to use software. These computers also use the
network’s server to perform some processing tasks. Network computers are
cheaper to purchase and to maintain than personal computers.
HANDHELD COMPUTER
In
the mid 1990s, many new types of small personal computing devices have been
introduced and these are referred to as handheld computers. These computers are
also referred to as Palmtop Computers. The handheld computers sometimes called
Mini-Notebook Computers. The type of computer is named as handheld computer
because it can fit in one hand while you can operate it with the other hand.
Because of its reduced size, the screen of handheld computer is quite small.
Similarly it also has small keyboard. The handheld computers are preferred by
business traveler. Some handheld computers have a specialized keyboard. These
computers are used by mobile employees, such as meter readers and parcel
delivery people, whose jobs require them to move from place to place.
The
examples of handheld computers are:
- Personal Digital Assistance
- Cellular telephones
PERSONAL DIGITAL ASSISTANCE (PDAs)
The
PDA is one of the more popular lightweight mobile devices. A PDA
provides special features such as taking notes, organizing contact numbers
and addresses. PDAs offer variety of applications such as word processing, spreadsheet and games etc. You can read books, and write notes by using PDAs.
Users can send and receive e-mails using PDAs. Most of the PDAs have telephone capability also available.
The
primary input device of a PDA is the stylus. A stylus is an electronic pen and
looks like a small ballpoint pen. This input device is used to write notes and
store in the PDA by touching the screen. Some PDAs also support voice input.
CELLULAR
PHONES
A
cellular phone or mobile phone is a telephone having features of analog and digital
devices. It is also known as Smart Phone. In addition to basic phone
qualities, a cell phone also provides the facility of sending and receiving of e-mail. .