CBSE Class 4 Computer Science Features, Uses and Basic Devices of a Computer Notes Set 01

What is a computer?

A computer is an electronic machine that takes in data, processes it and gives out useful information. It follows the instructions given to it and works very fast. Computers are used at school, at home, in hospitals, banks and railway stations.

Features of a computer

1. Speed. A computer can do millions of tasks in one second.

2. Accuracy. It gives correct results if the data and the instructions are correct.

3. Diligence. It does not get tired or bored, even after working for hours.

4. Versatility. It can do many kinds of jobs, such as writing, drawing, playing music and showing videos.

5. Storage. It can store a very large amount of information in a small space.

Limits of a computer

A computer cannot think on its own. It works only on the instructions that people give it. It has no feelings and cannot make decisions based on emotions, so it can never take the place of a human being. It needs people to switch it on, to give it correct data and to check the results it gives.

Where computers are used

1. Schools: to prepare results, keep records and teach through smart boards.

2. Hospitals: to keep patient records and to help doctors find diseases.

3. Banks: to keep accounts and records of money.

4. Railways: to book tickets and show train timings.

5. Entertainment: to make films, games and cartoons.

6. Science: to forecast the weather and to launch satellites.

Input, process, output

A computer works in three steps. First we give it data or instructions, which is called input. Then the CPU, or Central Processing Unit, works on the data, which is called processing. Finally the result is shown, which is called output. The CPU is called the brain of the computer.

Input devices

An input device is used to put data into the computer.

1. Keyboard: it has letter, number, function and special keys, and we type with it.

2. Mouse: it moves a pointer on the screen. It has two buttons and a scroll wheel.

3. Joystick: a pointing device with a handle, used mainly to play games.

4. Scanner: it copies a picture or page into the computer as a digital image.

5. Barcode reader: it reads the barcode on a product, for example at a shop's billing counter.

Output devices

An output device shows the result. The monitor is the main output device and displays pictures and text. The printer puts the result on paper. Printed paper is called a hard copy.

Worked examples

Example 1. Is a scanner an input or output device? It sends a picture into the computer, so it is an input device.

Example 2. Which device gives a hard copy? A printer prints the result on paper.

Example 3. Why is the CPU called the brain? It does all the processing, just as our brain does the thinking.

Remember

Input goes in, the CPU processes, and output comes out. Keyboard, mouse, joystick, scanner and barcode reader are input devices, while monitor and printer are output devices.

Quick Check Questions