CLASSIFICATION OF DIGITAL COMPUTERS:

Computers are classified according to size speed and memory capacity. Computers are of different types:

• Super Computers


• Main frame Computers


• Mini frame Computers


• Micro/PC/Desktop


• Laptop

Super Computers:
Super Computers are the largest, faster, and the most expensive computer system in the world. They are used to process complex scientific jobs. They are considered to be the resources (assets) of any nation. Super Computer are used to performed million of instructions at the same time. Very few companies in the world produce super computers. Cray research and ETA systems are two primary manufacturers of super computers in the United States. Fujitsu, Hitachi and NEC are the companies in japan, which produce super computers.
Use of the Super Computers:
Super computers are widely used in meteorological where weather patterns are predicted by manipulating vast amount of data.
Mainframe Computers:
The Mainframe Computers are the large computers available in different models, capacities and prices etc.
Examples: IBM 370, DEC 1090 and NEC etc.
Characteristics of Mainframe Computer
The main characteristics are:

• They are based on the principle of strong physical computing power. Many people can make use of the same machine at the same time.
• They are sensitive to variations in temperature, humidity, dust etc., and are hence in a controlled environment, i.e., air conditioned rooms.
• Qualified operators and programmers are required for their operations. They support
• Wide range of peripherals.
• They have a large storage capacity.
• They can make a use of wide range of software
• These systems generally support 500 to 2000 local and remote users

Mini Computers:
Mini Computers were introduced in the 1960s. They have less capacity to manipulate and store data, compared to mainframe computers. Examples: Digital Equipment Company (DEC) introduces first Mini frame computer called VAX.
Characteristics of Mini Computers
Some of the characteristic of minicomputers are:

• They offer limited range of peripherals.
• Limited software can be used.
• There is facility for direct operation of the machine by the end user
• Air conditioning is not necessary for minicomputers.
• Computers are widely used for data processing and in industry.
• These system generally support 10 to 200 users.

The Micro / Personal / Desktop Computers:
These computers are used now days commonly and these computers revolutionized the Computer industry because of their size and cost.
Some of the features are:

• They are cheap and easy to use
  
• They have limited input and output capacity
• They have low storage capacity
• The range of the software that can be used by one person at a time
  
• A visual display screen or a printer is used to get the output

Uses of the Microcomputers:
Most of the companies produced microcomputers. They are used for various applications. They are also used by million of a persons for entertainment and personal applications.
Laptop Computers:
There are light and compact and are called portable because they work on batteries and can operate without external power source. Laptop, which weigh from four to eight pound, are often called notebook PCs because they are about the size of a one-inch think notebook. These computers are fits in briefcase and they do not have to plug in. Most laptops accept diskettes, so it is easy to move data form one computer to another. Normally these computers are expensive.