(A Book on Computer Education)

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1 (A Book on Computer Education) (Class-IV) Publication Division D.A.V. COLLEGE MANAGING COMMITTEE Arya Samaj Building, UP Block, Pitampura, Delhi

2 S.NO. TOPIC PAGE NO. 1. Working of Computer System 1 2. Generation of Computer 8 3. Windows MS-Word More on MS-Word OpenOffice Draw More on OpenOffice Draw The Internet 71

parts of a computer correctly, write any five ways how a computer is used in your school. 1. 2. 3. 4. 5.

3 1 Working of Computer System In Class III, we learnt about a computer. Come, let us label the parts of a computer in the following picture: Now that you have labeled all the parts of a computer correctly, write any five ways how a computer is used in your school The above mentioned points show that a computer does a lot of jobs for us. Let us now learn about the working of a computer in this chapter. 1

COMPUTER AND ITS WORKING Students, do you like coffee shake? Do you know how is it prepared?

coffee and ice in a jar. Step II Mix all the ingredients with the help of a mixer.

INPUT PROCESS OUTPUT We first Input the ingredients, then, Process them and finally, we get the

Similarly, a computer also works in three steps: STEP I INPUT STEP II PROCESS STEP III OUTPUT The

For the Teacher Encourage the students to give some more daily life examples where we use these

DEVICES OF A COMPUTER A computer requires some devices for its working.

4 COMPUTER AND ITS WORKING Students, do you like coffee shake? Do you know how is it prepared? To prepare a coffee shake, we need to follow a few steps as shown below: Step I Put milk, sugar, coffee and ice in a jar. Step II Mix all the ingredients with the help of a mixer. Step III The coffee shake is ready. INPUT PROCESS OUTPUT We first Input the ingredients, then, Process them and finally, we get the Output, i.e. coffee shake. Similarly, a computer also works in three steps: STEP I INPUT STEP II PROCESS STEP III OUTPUT The steps mentioned above will be discussed in detail in this chapter. For the Teacher Encourage the students to give some more daily life examples where we use these three stages Input, Processing and Output to explain the working of a computer. DEVICES OF A COMPUTER A computer requires some devices for its working. These are categorised as Input Devices, Processing Device and Output Devices. Let us study them one by one. 1. Input Devices We all know that computer is a machine. It cannot do anything by itself. We have to tell a computer what to do. That means, we have to give it an Input (Step I). Let us first understand the term Input by the given example. 2

If we want a computer to add two numbers, say 10 and 12, then, we have to type these two numbers with a plus

Thus, the data or instruction given to a computer to do something is called Input.

Keyboard and Mouse are the two most commonly used input devices.

Some other Input Devices are: Scanner Input Devices Uses It works like a photocopier machine and saves paper.

Touch Screen It controls a computer by simply touching the screen by a finger.

5 If we want a computer to add two numbers, say 10 and 12, then, we have to type these two numbers with a plus sign '+' in between. Here, the numbers, 10 and 12 are the Data is the Instruction. Thus, the data or instruction given to a computer to do something is called Input. The devices that help a user to give input to a computer are called Input Devices. Keyboard and Mouse are the two most commonly used input devices. We have already used Keyboard and Mouse while working in MS-Paint and WordPad in Class III. Some other Input Devices are: Scanner Input Devices Uses It works like a photocopier machine and saves paper. Joystick It is used for playing games. Touch Screen It controls a computer by simply touching the screen by a finger. Microphone It is used to input sound. Webcam It is used for sharing images and videos on the Internet. For the Teacher Take the students to the Computer Laboratory. Give them demonstration of the working of different input devices. Activity Go to an ATM along with your parents. Tick ( ) the input device that you find there. Touch Screen Joystick 3

6 2. Processing Device Now, the Input, i.e. the instruction gets processed (Step II) in the other part, i.e. Central Processing Unit (CPU) of a computer. A Central Processing Unit (CPU) is a Processing Device that processes instructions entered through the input devices. A CPU processes instructions using its three parts: a. Control Unit (CU) b. Arithmetic Logical Unit (ALU) c. Memory Unit (MU) See the flowchart carefully: Input Device Do you know? The size of CPU is very small, though its power is great. ALU Performs calculations and comparisons on the data. CU Controls the flow of data and information. Central Processing Unit MU Holds data and results of processing. Output Device Let us understand it with the help of an example: Step 1. The instruction is entered through an input device. Step 2. CU takes the instruction. Step 3. CU sends the instruction to the ALU and stores it in MU. Step 4. ALU adds 10 and 12, and calculates the result as 22. Step 5. CU collects the answer and sends it to the MU and the output device. 4

3. Output Devices Now, after processing, we get the result, i.e. the Output (Step III).

The devices that are used to communicate the results of the processed data to a user are called Output

Some of the common Output Devices are: Monitor Output Devices Uses It is used to produce soft copy

It is of different types Cathode Ray Tube (CRT) Liquid Crystal Display (LCD) Thin Film Transistor Liquid

produce hard copy It is of two types Impact Printer (e.g.

Laser Printers and Ink-Jet Printers) It is used to produce output in the form of sound.

7 3. Output Devices Now, after processing, we get the result, i.e. the Output (Step III). Here, the output is 22. The devices that are used to communicate the results of the processed data to a user are called Output Devices. Some of the common Output Devices are: Monitor Output Devices Uses It is used to produce soft copy output from a computer. It is of different types Cathode Ray Tube (CRT) Liquid Crystal Display (LCD) Thin Film Transistor Liquid Crystal Display (TFT LCD) Light Emitting Diode (LED) Printer Speaker Headphone Projector It is used to produce hard copy output from a computer. It is of two types Impact Printer (e.g. Daisy-Wheel, Dot- Matrix and Line Printers) Non-impact Printer (e.g. Laser Printers and Ink-Jet Printers) It is used to produce output in the form of sound. It is used to produce sound. A sound can be heard by putting the headphone close to ears. It is used to show pictures on a big screen. Remember Input/Output can be in the form of text, pictures, sound, movies, etc. Soft Copy Output can be seen or heard through various output devices. Hard Copy Output can be obtained on a paper through printer. For the Teacher Take the students to the Computer Laboratory. Help them recognize the different output devices. 5

8 Something to Know A. Match the following. 1. Microphone (a) calculates and makes comparisons. 2. ALU (b) controls the flow of data and information. 3. Speaker (c) gives the hard copy output on a paper. 4. CU (d) helps to listen to sound from a computer. 5. Printer (e) inputs sound in a computer. B. Write True or False for the given statements. 1. A monitor is an output device. 2. The CPU processes a received instruction. 3. A printer is an input device. 4. Dot Matrix is a type of Mouse. 5. A computer works in three stages. C. Answer the following questions in brief. 1. Name the device that is used to share images and videos on the Internet. 2. Which device is used to produce a soft copy output? 3. Name the three steps involved in the working of a computer. 4. Name the different forms of Input/Output. 5. What do you understand by Input? D. Answer the following questions. 1. Define Input and Output devices. 2. What is a Central Processing Unit? 3. Differentiate between the following: (a) Printer and Scanner 4. Explain the three parts of a CPU. (b) Speaker and Headphone 5. Which are the two types of printers? Give examples. 6

9 Something to Do 1. Tick ( ) the correct stage. (a) Typing (b) Getting result 67 on a monitor (c) Calculating (d) Loading pictures from a Digital Camera (e) Comparing 27 and 32 (f) Listening to music Input Process Output 2. Collect the pictures of various Input and Output devices from magazines or newspapers and make a collage of it. 3. In the maze, move horizontally, vertically and diagonally to search the Input and Output devices. Take the help from the given clues. J O Y S T I C K M L S T X J K M O U S E M R S O H X C V B N E W E H C I Y E X C V B N K R A A P W L A X C R A V T S N R K K Z D A E X B Y D N O E G X T P L C N U F E J Y F C S R H V M I G R E B D V A I E O Y O H I C O S B S N R F N P J U T A A N D T T O I E K Y O R Q M W E B C A M L T R D M I C R O P H O N E K PRINTER SPEAKERS HEADPHONE PROJECTOR SCANNER JOYSTICK MICROPHONE WEBCAM MOUSE KEYBOARD 7

Input: is any data or instructions that are used by a computer.

1 What is input? Input: is any data or instructions that are used by a computer. Input devices: are hardware used to translate words, sounds, images, and actions that people understand into a form that