हिमाली शेर्पा


What is computer ?

Computer is an advance electronic device, which takes raw data then data as per given instruction then gives output (result) & store foe future use.

In other word:

The device which follows “IPO” cycle is called computer.

IPO = Input-Process-Output.

Input Process Output


Input = Mouse, Keyboard, Digital camera, Joysticks, etc.

Process = C.P.U.

Output = Monitor, Printer, Plotter.


It is a input device which provides raw data to the computer (alphabets, numbers, special characters).


I, Simple keyboard II, Multimedia keyboard.


It is also a common input device, which gives the facility to reach & click on desire options. The concept of mouse was first introduced by apple computer. But this concept was rejected by IBM (International Business Machine) Computer. After seeing the popularity of it. IBM also added such feature in “Windows”.


I) Mechanical Mouse.

II) Optical Mouse.

III) Wireless Mouse.


It stands for central processing unit. It consists of mainly three parts.

I) Central Unit.

II) Memory Unit.

III) Arithmetic & Logic Unit.


Monitor is an important output device, which gives result of given raw data & instruction. It is of visual one.


I) CRT Monitor. (Cathode Ray Tube Monitor)

II) LCD Monitor (Liquid Crystal Display)


for 14″ monitor : 800 by 600 pixels.

for 17″ monitor : 1024 by 768 pixels.

. : 1152 by 864 pixels.

. : 1240 by 1024 pixels.

Components of computer:

I) Hardware

II) Software

III) Humanware.

I) Hardware:

Physical parts of a computer which can see or realize.

II) Software:

It is simply a computer program.

III) Humanware:

It is a person who operates the computer & its periphery.

Characteristics of computer (Importance).

I) Speed:

It works under high speed. It calculates ‘MIPS’ i.e. “Millions of Instruction per Second.”

The speed of computer is measured in following terms:

1 millisecond : 1/1,000th of a second (10-3)

1 microsecond : 1/10,00,000 of a second (10-6)

1 nanosecond : 1/10,00,00,00,000 of a second (10-9)

1 picoseconds : 1/10,00,00,00,00,000 of a second (10-12)

II) Accuracy:

Computer does no mistakes if the input data & instruction are correct. It works on the principle ‘GIGO’ i.e. Garbage In Garbage Out.

III) Diligence:

Computers don’t get tired & slow the laziness of the same task has been given to it for many times. It does the same task with same speed & accuracy.

IV) Versatility:

It can be used in any field like science, education, business etc.


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