What is Computer?

Definition of Computer:

A Computer is a machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. A complete computer including the hardware, the operating system ( main software ), and peripheral equipment required and used for full operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster.

Computer are used as control system for a wide variety of industrial and consumer devices. This includes simple special purpose devices like microwave ovens and remote controls, factory devices such as industrial robots and computer - aided design, and also general purpose device like personal computers and mobile devices such as smart phones. The Internet is run on computers and it connects hundreds of millions of other computers and their users. 

 

History of Computer:

Pre 20th Century - Charles Babbage an English mechanical engineer and polymath, Originated the concept of a programmble computer. Considered the "Father of Computer", He conceptualized and invented the first mechanical computer in the early 19th century. After working on his revolutionary deference engine, Designed to aid in navigational calculations, in 1833 he realized that a much more general design, an Analytical Engine, was possible. The input of programs and data was to be provide to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory making in the first design for a general - purpose computer that could be described in modern terms as Turing - complete.

Concept of modern computer :

The principle of the modern computer was proposed by Alan Turing in his seminal 1936 paper, On Commutable Numbers. Turing proposed a simple device that he called "Universal Computing machine" and that is now known as universal Turing machine. He proved that such a machine is capable of computing anything that is commutable by executing instructions (Program) stored on tape, aollowing the machine to be programmable. The fundamental concept of Turings design is the stored program, where all the instructions for computing are stored in memory. Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Turing machines are to this day a central object of study in theory of computation. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing - complete, which is to say, they have algorithm execution capability equivalent to a universal Turing machine.

Type of Computers:

By architecture - 1. Analog computer

                              2. Digital computer

                              3. Hybrid computer

                              4. Harvard architecture 

                              5. Von Neumann architecture

                              6. Reduced instruction set computer

By size and form-factor - 1. Mainframe computer

                                            2. Super computer

                                            3. Mini computer

                                            4. Micro computer

                                            5. Workstation

                                            6. Personal computer

                                            7. Laptop

                                            8. Tablet computer

                                            9. Smartphone 

                                           10. Single board computer 

Input Devices:

When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are:

1. Computer keyboard

2. Digital camera

3.Digital vodeo

4. Graphics tablet 

5. Image scanner

6. Joystic

7. Microphone

8. Mouse

9. Overlay keyboard

10. Real - time clock

11. Touchscreen

Output Devices:

The means through which computer gives output are known as output devices. Some examples of output devices are:

1. Projector

2. Computer monitor

3. Sound card 

4. Printer

5. Video card

6. PC speaker

 

    

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