1. Classification of Computers

2. Classification of Computers
Purpose
General
Specific
Data Handling
Analog
Digital
Hybrid
Functionality
Micro
Desktop
Portable
Mini
Main Frame
Super

3. Classification of Computers According to Purpose
1) General Purpose Computers
Designed to perform a range of tasks.
Ability to store numerous programs.
Used for various application, Ranging from scientific to business purpose.
Versatile but lack in speed & efficiency.
Ex: Computers used in schools and home.
2) Specific Purpose Computers
Designed to handle a specific problem or to perform specific task.
A set of instruction is build into the machine for that specific task.
Cannot be used for other application unless its circuits are redesigned.
Lacked in versatility but can provide result very quickly and efficiently.
Ex: Computers used for airline reservation, Satellite tracking or air traffic control.

4. Classification According to Type of Data Handling Technique
1) Analog Computers
Works on the principle of measuring, in which the measurements obtained are translated.
Do not directly deals with numbers, Measures continuous physical magnitude (temp, pressure, Voltage).
These computers are very fast in operation but lack in accuracy.
Example: Analog computer in petrol pump that converts flow of petrol into quantity and price.

5. 2) Digital Computers
Operates with information represented in digital form.
Process data(Text, sound, graphics, video) into a digital value ( 0 & 1).
Analog quantities must be converted into digital before processing.
In this case output is also digital but if desired can be converted into analog quantity.
Accuracy of these computers depends upon size of their registers and memory.
Example: Desktop PC

6. 3) Hybrid Computers
Incorporated the measuring feature of analog computer and counting feature of digital computer.
These computers use the analog components for computational purpose and to store the immediate result it uses digital memories.
The hybrid computer uses the converter (Digital to analog & Vice-versa) in order to bind the powers of digital and analog techniques.
Used for scientific application, various field of engineering, Industrial control process.

7. Classification According to Functionality
Based on size, performance and application areas.
1) Micro computers
Small and low cost digital computer, Usually consist of a micro-processor, a storage unit and output channel.
Examples: IBM-PC, APPLE etc
Desktops:
Most common micro computer consist of system unit, monitor, keyboard, hard-disk & other peripheral devices.

8. Classification According to Functionality
Laptop:
Portable computer enclosing all the basic features of a normal desktop computer.
The biggest advantage is that one can carry and use this computer anywhere.
Laptops do not any external power supply.
Hand-Held Computers
PDA is a computer that can easily stored in a pocket.
It generally uses a pen or electronic stylus as input device.
Usually have no disk drive, It uses small card to store program and data.

10. 2) Mini Computers
Small digital computer, which normally able to process and store more data than micro computers.
Size of mini computer is bigger than micro computer.
Designed to meet computing needs of small and medium size business environment.
Support 4 to 200 users simultaneously.
Ex: PDP11, IBM8000 series.

11. 3) Main frame computers
Ultra high performance computer made for complex computing.
It consist of a high-end computer processor with related peripheral devices.
Capable of supporting large volume of data processing, high performance on-line transactions processing system and extensive data storage & retrieval.
It is designed to perform faster and store more data than mini computer.
Usually executes many programs simultaneously with high speed.
Allows users to maintain large information storage at a centralized location and be able to access and process this data from different computers located at different locations.
Typically used for large business and scientific purpose.
Ex: IBM’s ES000, VAX 8000, CDC 6600.

13. 4) Super computers
Special purpose machines, which are specially designed to maximize the efficiency.
A super computer has the highest computing speed for solving scientific and engineering problems.
It contains a number of CPUs that operate in parallel to make it faster.
It can process large amount of information and make extensive calculation quickly.
Super computers are fastest, costliest and most powerful computers available today.
Ex: CRAY-3, Cyber 205, PARAM

15. Workstation
A workstation is a high-end microcomputer designed for technical or scientific applications. Intended primarily to be used by one person at a time,
They are commonly connected to a local area network and run multi-user operating systems.
The term workstation has also been used to refer to a mainframe computer terminal or a PC connected to a network.

16. Server
A server is any combination of hardware or software designed to provide services to clients.
Process that shares a resource to one or more client processes is a Server.
Example:
1)File sharing
2) web server