Friday, 23 October 2015

CLASSIFICATION OF COMPUTERS


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.

Personal computers are available in two models. These are:

  1. Desktop PCs
  2. 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.

  1. Laptop computer
  2. Workstation
  3. Network computer
  4. 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:

  1. Personal Digital Assistance
  2. 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. .

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