Oasis Radiant Computer Science Grade 4 By Er. Shankar N. Adhikary
Oasis Radiant Computer Science Grade 4 Written by Er. Shankar N. Adhikary Layout Design: Zeeta Computer Service Pvt.Ltd. Ghantaghar, Kathmandu Publisher: Oasis Publication (P) Ltd. Anamnagar, Kathmandu Nepal Tel: 977-01-4313205 www.oasispublication.com.np Printed in Nepal © Publisher First edition : 2017 Second edition : 2018 Revised Edition : 2022
Oasis Radiant computer science Grade Four 3 Chapter Titles Page No. Chapter 1 Introduction to Computer 5 Chapter 2 Applications and Characteristics of Computer 11 Chapter 3 Input and Output Devices 17 Chapter 4 History and Generations of Computer 27 Chapter 5 Some Computer Peripherals 34 Chapter 6 Types of Computers 44 Chapter 7 The Internet 53 Chapter 8 Understanding Microsoft Word 59 Chapter 9 Understanding Microsoft PowerPoint 96 Chapter 10 MS Paint 114 CONTENTS
Acknowledgement We are living in the 21st century. This is the age of Information and Communication Technology (ICT). ICT has become an integral part of our daily life. It facilities the business professionals, academicians, students, banking and other sectors. It has become a fundamental right of children to get computer education. They have to get the basic to advance knowledge of computer to cope the changes in future. The Government of Nepal has prescribed the syllabus and course outline for the computer education from primary to higher secondary level. Students are not able to get quality computer education due to the lack of quality text books and the limited access to the computer system in schools. To address this scenario, I have developed the complete series of computer book with name Oasis Radiant Computer Science from grade I to grade XII. I have devoted more time for the research and development for the preparation of this book. It provides a comprehensive and balanced coverage at the CDC syllabus. It is possible due to the comprehensive support of my colleges, family members, students and the teachers. I would like to acknowledge all who have directly or indirectly encouraged me to prepare this book. Specially, my thanks go to the students and teachers of different schools for their regular interactions and inspirations to prepare this book. In the same way my thanks go to my parents Tek Nath and Chisa Maya Adhikary, family members Lachhima Adhikary, Jagan Adhikary, Sarashwati Adhikary and lovely kids Samridhi, Sampada, Prasamsha, Ballavi, Ragavi, Suyash and Suyasha Adhikary for their valuable contribution to prepare this book. I must give thanks to OASIS PUBLICATION family for their innovative help to prepare and publish this book. Finally, all the suggestions and comments are acknowledged. Thanking all. Er. Shankar N Adhikary Tarkeshwor, Kathmandu [email protected]
Introduction to Computer 1 Chapter List the advantage of computer Define computer Describe the structure of computer List the limitations of computer
6 Oasis Radiant computer science Grade Four 1 Introduction to Computer CHAPTER There are different types of devices around us. These devices are developed to ease our day to day life. Our day to day life is becoming more and more complex. So, some advanced devices are required to make the life easier. Computer is a modern electronic device that makes our life easier. “Computer is an electronic device that accepts data and instructions as input and stores them in the memory for further processing to give desired result as output to the user.” It works automatically with the help of program and instructions given. Computer has input section, processing and storage section and output section. Input section captures the input and converts it into machine code and delivers to the processing section of the computer. Processing section processes the data according to the instruction and logic given to the system. Memory section stores the data for future purposes. Output section gives the result to the user. In other words computer is a high-speed electronic device that can process huge amount of data to give information as output. So, sometimes it is also called data processor. Structure of the Computer Structure of the computer deals with the physical and anatomy parts of the computer. Physically, we can see the computer like a Television set with Central Processing Unit (CPU) and Keyboard. Moreover, computer system has some additional parts like Volt guard, mouse, printer, speaker, etc. We can see the following physical structure of computer.
Oasis Radiant computer science Grade Four 7 We can see the external and internal components of computer in the above figure. The internal structure is very complex. The devices connected to the computer system as given in the figure are called computer peripherals. According to the above figure, external components are monitor, speaker, mouse, keyboard and the case. Inside the case, it has different components as given in the figure. These are Power supply, DVD drive, motherboard, microprocessor which is also called CPU and CPU fan, random access memory, video graphic adaptor (VGA) card, sound card, hard disk, etc. Advantages of Computer Computer is a fast processing and automatic device. It has huge amount of memory and performs complex task according to the instructions and the program. It is very useful in our daily life. We can list some major advantages of the computer as below: 1. We can use it for storing huge amount of data. 2. It can solve complex problems within a fraction of second. Power supply DVD ROM Drive Motherboard CPU CPU Fan RAM VGA Card Sound Card Reader all-in-one Internal Harddisk Speaker Monitor Keyboard Mouse
8 Oasis Radiant computer science Grade Four 3. It is used for designing the home appliances and advance electronic devices. 4. It is very useful for communication system. 5. It is used to send emails and browsing internet. 6. It is used for advertising and film making. Limitations of Computer Computers are very powerful and highly reliable machines. But they have some limitations. 1. Computer is an artificial device so it has no self-thinking power. 2. It requires neat and clean environment. 3. Computer is very expensive. So all the people cannot afford the computer. 4. Skilled user is required to operate and maintain the computer. Chapter Review Computer is an electronic device, which accepts data and instructions. Keyboard, scanner, mouse are the popular input devices used in the computer. Output devices are the devices that give output according to the input given to the computer. Monitor, printer are some examples of output devices. Computer is a high-speed electronic device which can process a huge amount of data as well as instructions. Devices connected to the computer system are called computer peripherals. Computers are applied for solving many day to day complex problems. Computers are used in hospitals, pharmacies, labs and many other medical work.
Oasis Radiant computer science Grade Four 9 Exercise 1. Fill in the blanks with suitable word. a. Computer is an ………... device. b. Computer accepts the ……….and instructions. c. Physically we can see computer like a ……….screen. d. Computers have very high ……..capacity. e. Computer cannot ……….. f. ALU stands for …………….. g. ………..user is required to work with the computer. 2. State whether the following statements are True or False. a. Computer is an electronic device. b. Computer cannot do anything without instructions. c. CPU stands for Central Parallel Unit. d. Computer has very high speed. e. Computer gets tired when it works for a long time. f. Computer is an expensive device. g. Computer is not suitable for research and development. h. Repair and maintenance should be frequently done. i. Computer can be used on publication houses. 3. Answer the following questions. a. What is a computer? b. List some external parts of computer system. c. List some internal parts of computer system. d. Write any four characteristics of computer. e. List out the application areas of computer. f. Mention some limitations of computer.
10 Oasis Radiant computer science Grade Four 4. Match the following: Internal structure Volt guard External structure Control unit Input device Monitor Output device Arithmetic and Logical Unit ALU Keyboard 5. Project work a. Collect some pictures of internal and external parts of computer and paste them. Use separate paper if necessary.
Applications and Characteristics of Computer 2 Chapter Describe the uses of computer Describe the characteristics of computer Write the fraction of second
12 Oasis Radiant computer science Grade Four Applications and Characteristics of Computer 2 CHAPTER Applications of computer As we discussed in the previous chapter, computer is a very powerful system. It is applicable to an individual’s task as well as official uses. It is a highly efficient electronic device capable of performing a number of complex operations in a fraction of second. It has internal storage, a stored program and program modification capabilities. There are several areas where computers are frequently used. Some popular application areas are discussed below. Business fields Computer is applicable for documentation and billing in the business houses. User can handle the inventory, sales , billing and other marketing activities using computer. Schools and colleges Schools and colleges are using computer for teaching and learning process. They are using computer for result processing and student record handling. Students can learn the lesson with the help of CDs and DVDs, Internet and other digital data. Publication and newspaper Computers are used for designing and developing newspapers and the books. Designers can use graphs, text and other contents to make a new design.
Oasis Radiant computer science Grade Four 13 Hotel and restaurant Computers are more useful for online communication and exchanging documents using the internet system. Computer can be used for hotel management, front deskwork and other documentation. It is used for hotel reservation and billing. Industrial fields Computers are used for designing and developing new products. They are used to handle the production process and design of new product. They are used for payroll, accounting, inventory and production control. Science and engineering Computers are used to solve the complex mathematical and design problems. They are used in the field of the science and engineering. They are used to draw some engineering drawing to design building using Auto- CAD (Automatic - Computer Aided Design) program. Communication fields Now a days people are using computer system for the communication. They are using it for telephone calls, emails and internet for communication. Accounting fields Accounting software is used to handle the accounting process. It is used in accounting and financial system. It is applicable for the payroll, cash handling, balance sheet, bill preparation.
14 Oasis Radiant computer science Grade Four Research and development Research and development is a very challenging task. Researchers and development workers are using computer in research and development for problem analysis and mathematical calculations. Characteristics of Computer Computer is a very intelligent machine. It has some unique features which are not available in other electronic devices. The major features of computer are discussed below: Speed As you know, computer can work very fast. It takes fractions of second for calculations that we take some days to complete. It can perform millions (1,000,000) of instructions within a fraction of second. We can determine the speed of computer in terms of Microsecond (10-6 part of a second), Nanosecond (10-9 part of a second) and Pico second (10-12 part of a second). Accuracy It has a very high accuracy. It can calculate at a high speed without any errors. But the accuracy of the computer depends upon the accuracy of the input given to the computer system. Versatility It means the capacity of computer to perform completely different works. Same computer can be used to prepare bill, newspaper and graphic design and internet connections and play movie, etc. Diligence Diligence means free from tiredness, lack of concentration, fatigue, etc. Computer is a diligent device because it can work for many hours without making any errors. High memory Computer has very high memory. We can store a huge amount of data in computer. It has the power of storing huge amount of data and information.
Oasis Radiant computer science Grade Four 15 All information can be stored and recalled according to our requirement. There are different types of storage devices used for storing the data. They are hard disk, pen drive, floppy disk, compact disk, etc. Chapter Review A computer is an efficient electronic device capable of performing a number of complex operations within a limited time. We can use computer for result processing and student record handling. Computer is applicable to business for inventory control, accounting, bills and sales report. Computer is used for newspaper preparation, advertisement, word processing and graphic design. Computer is used for payroll, accounting, inventory and production control. Computer is used in accounting process and financial system. Computer takes few seconds for calculations. A computer is a diligent device because it is free from tiredness, lack of concentration, fatigue, etc. Versatile means the capacity of computer to perform completely different works. Computer has the power of storing huge amount of data and information. Exercise 1. Fill in the blanks with suitable word. a. Computer is an efficient device capable of performing a number of ………….operations. b. Computer has …………..to store programs. c. We can use computer at schools and colleges for ……..and student record handling.
16 Oasis Radiant computer science Grade Four d. Computer is used for ……….reservation and billing. e. Computer can work at a ……..speed. f. Diligence means it is free from ………….. 2. State whether the following statements are True or False. a. Computer is a versatile machine. b. Computer cannot be used in education. c. Computer is not much applicable for entertainment. d. The processing capacity of computer is very low. e. Accuracy means it calculates faster but commits mistakes. f. Versatility means computer can be used everywhere. 3. Answer the following questions. a. Why is computer efficient electronic device? b. What are the application areas of computer? c. For what purpose computers are used at schools and colleges? d. Can you reserve air ticket with the help of a computer? e. Why is computer called accurate machine? f. What do you mean by the term ‘versatility’? g. What are the different types of storage devices for storing the data? 4. Match the following: Electronic device Calculate faster without errors Education field Computer Business field Result processing Accuracy Advertisement designing 5. Project work a. How is computer used in the following fields? Explain. i. Computer in education ii. Computer is science and technology iii. Computer at bank
INPUTDEVICES OUTPUT DEVICES This chapter covers: Input and Output Devices 3 Chapter
18 Oasis Radiant computer science Grade Four 3 Input and Output Devices CHAPTER Introduction You might be aware that computers have four major components: input, process, output and memory. Out of them, let's learn more about input devices and output devices. Input Devices Can you cook rice without water ? Of course, your answer is, 'NO' ! Common example of Input - Process - Output in our daily life Input ( Rice, water) Processing (Rice cooking) Output (Cooked rice) Input - Processing - Output in Computer Input Unit Keyboard Processing Unit CPU Output Unit Monitor
Oasis Radiant computer science Grade Four 19 Similarly, computers can not perform any task without input. The devices that are used to enter data and instructions into a computer are input devices. They are the basic parts of a computer. The most commonly used input devices are a keyboard and a mouse. On the basis of their work, the input devices are categorized into : ● Text Input Device ● Pointing Device ● Audio Input Device ● Video and Image Input Device Text Input Device A device which is used to input text and characters is called Text Input Device. Example: Keyboard Keyboard A keyboard is one of the important input devices of a computer. We can enter data and instructions into the computer through a keyboard. A keyboard has different sets of keys to perform various operations. They are: alphabet keys, numeric keys, function keys, cursor control keys and special keys. Pointing Input Devices The input device which is used to move the pointer on the screen is known as a pointing device. For example: mouse, trackball, light pen, joystick. i. Mouse A mouse is a commonly used input device. It is a pointing device that is moved by hand on a flat surface. A mouse may have two or three buttons. 'Click', 'Double click', 'Right click' and 'drag and drop' are the basic operations of a mouse. Keyboard Mouse
20 Oasis Radiant computer science Grade Four ii. Light Pen A light pen is a pen like pointing device. It can be used to select an option by simply pointing to it. The light pen is mainly used by engineers, architects or fashion designers for drawing directly on the screen. iii. Joystick A joystick is also a pointing device. It can be used to move the cursor rapidly on the screen. It is mainly used while playing games. iv. Trackball A trackball is also a pointing device. The users roll the ball with the thumb or fingers to move a cursor. Trackballs are mostly used in portable computers like laptop. Audio Input Device The device which is used to input the sound into the computer is known as audio input devices. For example: microphone. Microphone A microphone is an audio input device. It is used for recording voice, sound and music into the computer. Light Pen Joystick Trackball Microphone
Oasis Radiant computer science Grade Four 21 Video and Image Input Device The device which is used to input video and images into the computer is called a video image input device. For example: scanner, digital camera, webcam. i. Scanner A scanner scans or captures text and pictures directly into the computer. Scanners can capture the images in black and white or in different colours. ii. Digital Camera A digital camera is an input device that takes photos and input them into a computer in digital format. iii. Webcam A webcam is an input device that looks like a video camera. It is also known as PC camera. It is widely used for Internet chatting. Output Devices Output means the processed data or result. When you give data and instructions through input devices, they are processed by CPU and displayed by output devices. The devices that provides output as information to the user are called output devices. There are two types of output: i. Softcopy output ii. Hardcopy output Digital Camera Scanner Webcam
22 Oasis Radiant computer science Grade Four A. Softcopy Output The output displayed on the monitor is called a softcopy output. These outputs can be modified and erased if needed. Examples of softcopy output devices are monitor and speaker. i. Monitor A monitor is the most common output device. In appearance, it looks like a TV screen. Monitors are available in different sizes. The sizes available are 17 inches, 19 inches, 21 inches and others. It is also called VDU (Video Display Unit). There are three types of monitors on the basis of technology. i. CRT(Cathode Ray Tube) ii. LCD(Liquid Crystal Display) iii. LED(Light Emitting Diode) CRT(Cathode Ray Tube) LCD(Liquid Crystal Display) LED(Light Emitting Diode) ii. Speaker A speaker is a softcopy output device.It is used to listen to sound and music from the computer. It can be of different shapes and sizes. B. Hardcopy Output The output which we get on paper is a hardcopy output. This output is permanent and can be kept for future reference. Example of a hardcopy output device is printer. Speaker
Oasis Radiant computer science Grade Four 23 Printer A printer is the most popular hardcopy output device. The output given by a printer is usually printed on paper. There are different types of printers available. Some of them are shown below: Dot matrix printer Inkjet printer Laser Printer Flex printer
24 Oasis Radiant computer science Grade Four Chapter Review • Input devices are used to enter data and instructions. A keyboard is used to enter text into the computer. • A keyboard contains alphabet keys, numeric keys, functional keys, cursor control keys and special keys. • A mouse, a joystick, a light pen and a trackball are pointing input devices. • A scanner, a digital camera and a webcam are video image input devices. • The device that is used to display output or result in a computer is an output device. • Softcopy and hardcopy are two types of output. • A monitor and a speaker are softcopy output devices. The output that we get from a printer on a paper is known as a hardcopy output. Word Meanings input : data entered into the computer. processing : performing calculations and comparing data. output : result given by the computer after processing the data. drag and drop : an action of the mouse while moving a file or folder from one location to another location. architect : a person whose job is to design buildings and bridges. notebook : a small computer that works with the help of a battery and can be easily carried from one place to another. capture : to take image, text in a computer as input. scan : to copy picture on a monitor by passing light over it. permanent : long lasting that can be used in future.
Oasis Radiant computer science Grade Four 25 Exercise 1. Put a tick mark (√) on the best answer. a. Which of the following is not a pointing device? mouse keyboard light pen track ball b. Which of the following gives hardcopy output? monitor speaker printer none of these c. Which of the following are types of keys on the keyboard? alphabet keys special keys numeric keys all of these d. Which one is an audio input device? speaker microphone monitor printer e. Which of the following displays output in softcopy? monitor printer keyboard mouse 2. Fill in the blanks from the given 'Help Box'. Help Box monitor, microphone, text, scanner, softcopy a. A keyboard is a commonly used .................... input device. b. A speaker is a ............................. output device. c. A ................... copies text and pictures directly into the computer. d. A............................ looks like a TV screen. e. A .................... is used for recording voice, sound and music into the computer. 3. Identify me . Who am I ? a. I input text in the computer.
26 Oasis Radiant computer science Grade Four Ans: ……........................…………………….......................................... b. I produce the softcopy output and people use me to listen to songs and music. Ans: ......................…………………………............................................ c. I look like a video camera and I am mostly used in Internet for video chatting. Ans: …........................……………………….......................................... d. I am a hardcopy output device and I print text and image on paper. Ans: ….......................………………………........................................... e. I am a pointing input device and I am mostly used in a laptop and notebook computers. Ans: …......................………………………............................................ 4. Answer the following questions. a. What do you mean by input devices? Ans: …......................………………………............................................ b. Name any four pointing input devices. Ans:…......................………………………............................................. c. What is an output device? Ans: …......................………………………............................................ d. What is the use of a joystick? Ans: …......................………………………............................................ …......................……………………….............................................. e. What are the different keys in the keyboard? Ans: ….................................................................................................... ….....................………………………...............................................
History and Generations of Computer 4 Chapter Compare different generations of computers Describe the history of computer Explain different manual devices Describe the generations of computer
28 Oasis Radiant computer science Grade Four History and Generations of Computer 4 CHAPTER Computing is related to the number system and processing the numbers for calculations. So the history of computer refers to the history of counting. Various types of manual, mechanical and electronic devices are used for counting. Most popular devices are Abacus, Napier Bone, Slide rule, etc. Abacus It is the first calculating device. The Chinese people developed the first calculating device called Abacus. This has three parts. Upper part is heaven; lower part is earth and there is middle bar in between. Beads are used to count the numbers. Each bead on earth has the value of one and the beads on heaven have the value of five. Napier’s Bone It is also a manual device. English mathematician John Napier built a mechanical device for the purpose of multiplication in 1617 A D. The device was known as Napier’s bone. Slide Rule English mathematician William Oughtred developed the slide rule in 1620. It consists of a fixed scale and one movable scale over the fixed scale. It was widely used in Europe in 16th century. Heaven Mid bar Earth
Oasis Radiant computer science Grade Four 29 Pascal’s adding and subtraction machine Blaise Pascal developed a machine at the age of 19. It consists of some wheels, gears and cylinders. It could add and subtract the numbers. It was developed in 1642. It is popular with the name of Pascaline. Babbage’s analytical engine Charles Babbage invented the first structured computer. So, he is known as the father of computer. He built a mechanical machine to do complex mathematical calculations in 1823 AD. It was called a difference engine. Later, he developed a general-purpose calculating machine called analytical engine. Modern electronic computer On the basis of the concept of Charles Babbage, IBM (International Business Machine) company developed some electronic computers. It was the first computer manufacturing company. Now a days, you can see different types of computers with different models and brands. Now Pentium computers with high memory and high processing capacity are available in the market. We have different models of Micro computers. They are Personal Computer (PC), Laptop Computer, Apple Macintosh Computer, etc. Generations of computer According to the time and the memory devices used in the computers, we can classify them in five generations. As explained on the history of computer, the evolution of computer took place rapidly developed in five generations.
30 Oasis Radiant computer science Grade Four First Generation Computer First generation computers used vacuum tubes as major electronic components. They were large in size. It was difficult to use. Some of the computers of this generation were: ENIAC (Electronic Numerical Integrator and Calculator) and EDVAC (Electronic Discrete Variable Automatic Computer) Second Generation Computer Computers which used transistors as the major electronic components are second generation computers. Around 1955, a device called transistor replaced the bulky vacuum tubes in the first generation computer. They were faster and more powerful to work than the first generation computers.
Oasis Radiant computer science Grade Four 31 Third Generation Computer Computers that used the Integrated Circuit (IC) as the major electronic component are called third generation computers. Third generation computers were introduced in 1964. Eg. IBM-360, ICL-1900, IBM-370, etc. Fourth Generation Computer Modern computers that have input, processing, high memory and the advanced output section are fourth generation computer. They use the Very Large Scale of Integration (VLSI) and Large Scale of Integration (LSI) memory chips. These started around 1975. Large Scale Integrated Circuits (LSIC) built on a single silicon chip are called microprocessor. Due to the development of microprocessor, it is possible to place computer’s central processing unit (CPU) on a single chip. These computers are called Microcomputers. Later, a Very Large Scale Integrated Circuits (VLSIC) replaced LSICs. The personal computer (PC) that you see in your school is a Fourth Generation Computer. Fifth Generation Computer Modern computers that use ULSI (Ultra Large Scale of Integration) are fifth generation of computers. These computers are going to be developed. These are in test phase in the lab. The concept of AI (Artificial intelligence) has been introduced to allow the computer to take its own decision. It is still in a developmental stage.
32 Oasis Radiant computer science Grade Four Exercise Chapter Review The Egyptian and Chinese people developed the first calculating device called Abacus. English mathematician John Napier built a mechanical device for the purpose of multiplication in 1617 A D. English mathematician William Oughtred developed the slide rule in 1620. Blaise Pascal developed a machine at the age of 19. A famous English man Charles Babbage built a mechanical machine to do complex mathematical calculations in 1823 AD which was called difference engine. First generation computers used Thermion valves called Vacuum Tubes. First generation computers were large in size. Second generations computers were faster and more powerful than the first generation computers. The third generation computers were introduced in 1964. The present day computers that you see today are the fourth generation computers. The concept of AI (Artificial intelligence) has been introduced to allow the computer to take its own decision. 1. Fill in the blanks. a. Abacus was developed by ……….. b. English mathematician John Napier built a machine called ………… c. ………………is called the father of computer science. d. ENIAC belongs to ………….generation.
Oasis Radiant computer science Grade Four 33 e. The memory component of the third generation computer was …....… f. VLSI belongs to …………generation. g. Slide rule was developed in …………… 2. State whether the following statements are True or False. a. Slide rule was the first calculating device. b. Pascal was the father of computer science. c. First generation of computer was faster than the second generation. d. ENIAC belongs to first generation of computers. e. Slide rule was developed by William Oughtred. f. IBM – 370 belongs to the third generation of computers. g. The concept of Artificial Intelligence will be used in fifth generation of computers. 3. Answer the following questions. a. What was the first calculating device and who developed it? b. When was Napier’s bone invented? c. Who gave the concept of modern digital computer? d. Write down the name of different computer generations. e. What is fifth generation computer? f. What are the memory components used by second and third generation computers? 4. Match the following: Vacuum tube Second generation Transistor First generation Integrated circuit Fifth generation Artificial intelligence Third generation 5. Project work a. Collect different pictures from internet about history and generations of computer and paste them in your project work.
Some Computer Peripherals 5 Chapter Describe input and output devices. Describe memory system in computer. Describe computer peripheral devices. What is CPU?
Oasis Radiant computer science Grade Four 35 Some Computer Peripherals 5 CHAPTER Computer system has input and output devices. These input and output devices connected to the computer are called computer peripherals. Computer system is the group of devices like keyboard, monitor, mouse, CPU (Central Processing Unit), printer, etc. Among them, some work as the input device, some as processing unit and others work as the output device. The detail description of the computer peripherals is given below: Monitor Monitor is a visual display unit of the computer that gives the soft output to the user. It is the most popular output device. There are three types of monitors. They are LCD (Liquid Crystal Display) monitor, CRT (Cathode Ray Tube) monitor, and LED (Light Emitting Diode) monitor. LED and LCD monitor are more advanced than the CRT monitor. Keyboard Keyboard is a popular input device from where we can enter the data and instructions to the computer. There are different types of keyboard. Which are wired keyboard, wireless keyboard, advanced technology keyboard, extra technology keyboard and enhance keyboard. According to the model and brand of the keyboard, it has different numbers of keys. Some popular keys are discussed below: Alphabet Keys Keys used to type the text are alphabet keys. We have A-Z and a-z keys in the keyboard. These are the most useful keys used by the users.
36 Oasis Radiant computer science Grade Four Escape Key You can press Esc to quit a task you are performing. Caps Lock and Shift Keys These keys are used to enter text in uppercase (Capital Letter) and lowercase (Small Letter). Press Caps Lock to change the case of all letters . Press the key again to return to the original case. Press Shift in combination with another key to type an uppercase letter. Numeric Keypad When the Num Lock light is on, you can use the number keys (0 through 9) to enter numbers. When the Num Lock light is off, you can use these keys to move the cursor around the screen like arrow keys. To turn the light on or off, press Num Lock. Function Keys These keys are used to perform specific tasks quickly. There are twelve function keys in keyboard. These are F1, F2, F3, F4..... F12. Ctrl and Alt Keys You can use the Ctrl (Control) or Alt (Alternate) key in combination with another key to perform a specific task. For example, in some programs you can press Ctrl and S to save a document.
Oasis Radiant computer science Grade Four 37 Enter Key You can press Enter to tell the computer to carry out a task. In a word processing program, press this key to start a new paragraph. Backspace Key You can press Backspace to erase the character to the left of the cursor. Delete Key You can press Delete key to erase the character to the right of the cursor. Arrow Keys These keys are used to move the cursor around the screen. There are four arrow keys on keyboard. CPU (Central Processing Unit) It is the main part of the computer so it is also called the brain of the computer. It works like the human brain. It has the capacity to memorise, process logically and arithmetically and control all types of activities. The full form of CPU is Central Processing Unit. It consists of three sections: - i. ALU (Arithmetical and Logical Unit) ii. CU (Control Unit) iii. MU (Memory Unit) ALU (Arithmetic and Logical Unit) Arithmetic and logical unit helps to process the data in the computer. This unit is an important unit for data processing. All the inputs given to the computer are processed in this section. CU (Control Unit) Computer system has two types of flow: data flow and control flow. Control signal can control the overall activities of the computer. So this unit is Memory Unit Control Unit ALU CPU
38 Oasis Radiant computer science Grade Four responsible to control the overall process of the CPU. This section checks and controls all the functions of the computer. MU (Memory Unit) This is known as the brain of the computer. It is the main storage section of the computer. Thousands of data and instructions are stored in this unit. Types of Memory We have two types of memory called primary and secondary memory. Primary Memory Memories which are inside the computer system are called internal memory. There are two types of primary memory. They are RAM (Random Access Memory) and ROM (Read Only Memory) RAM (Random Access Memory) The full from of RAM is Random Access Memory. Information stored in this memory is electrically dependent and erasable. It means, if you turn off the computer, the information will be erased. So, they are called temporary memory. ROM (Read Only Memory) The full form of ROM is Read Only Memory. This is permanent memory and fixed in the processing part of the computer. Different types of ROM are: - PROM (Programmable Read Only Memory) EPROM (Erasable and Programmable Read Only Memory) EEPROM (Electrically Erasable and Programmable Read Only Memory)
Oasis Radiant computer science Grade Four 39 Memory Unit We can measure the memory in terms of Byte, Kilobyte, Megabyte, Gigabyte and the Terabyte. The unit conversion is given below. 0 and 1 1 Bits 8 Bits 1 Byte 1024Byte 1 KB (Kilo Byte) 1024KB 1MB (Mega Byte) 1024MB 1 GB (Giga Byte) 1024 GB 1 TB (Tera Byte) Secondary Memory Memory systems which are used to store data for a long time are secondary memory. These are also called external memory. There are two types of secondary memories. Some popular secondary memories are: Floppy Disk Highly portable device that is used to store data using Floppy Disk Drives are floppy disk. It is denoted as A, B drives in computer system. It is small in capacity but frequently used to carry data from one computer to other computers. It is made up of a plastic coated with magnetic substances. Now a days it is almost replaced by other storage devices. Hard Disk It is the main secondary storage used in computer system. It is denoted as C, D, E and F Drives in computer system. It is fixed inside the computer as mass storage media. Hard Disk is used to store a large amount of data. The storage capacity is measured in GB(Giga Byte) and TB (Tera Byte).
40 Oasis Radiant computer science Grade Four Computer Case Computer case is a style box that contains all the internal devices of the computer. It contains all the major components of a computer system like motherboard, microprocessor, memory, etc. This is also known as the CPU section of the computer system. Case does not have any important function. Printer Printers are the hard output devices that prints the output on the paper. We can print the documents with different quality using the printer. We can get different types of printers like Laser printer, Dot matrix printer, Canon printer, and Bubble Jet printer. MoDem The device which is used in communication and data transfer is called MoDem. It is the device that can convert analog signal to digital and digital signal to analog. Full form of Modem is Modulation and Demodulation. There are different types of Modem. These are internal Modem and external Modem, etc. Without using this system, it is impossible to work with Internet and E-mail.
Oasis Radiant computer science Grade Four 41 Mouse Mouse is a pointing device that helps to select the options from the menu. It is a hand-held pointing device. It is used to select and move items on the screen. It has two buttons to select an item. We can get wired, wireless, optical and mechanical mouse in the market. Scanner Scanner is an input device that can convert the data into graphic format and send to the processing unit. A scanner reads graphics and text data and give it to the computer. There are various types of scanner like handheld scanner, sheet fed and flat bed scanner. Hand Held Sheet Fed Flat Bed Chapter Review All the parts connected to the computer are called computer peripherals. There are three types of monitors, They are Liquid Crystal Display, Cathode Ray Tube, LED (Light Emission Diocle). Caps Lock and Shift keys are used to enter text in uppercase and lowercase. You can press Caps Lock to change the case of all letters. Function Keys are used to perform specific tasks quickly. Backspace Key helps to erase the character to the left of the cursor.
42 Oasis Radiant computer science Grade Four The full form of CPU is Central Processing Unit. It is the main part of computer. Arithmetic and Logical Unit is an important unit for data processing. Control Unit controls the overall process of the CPU. Memory Unit is known as the brain of the computer. It is the main storage section of computer. Primary Memory is inside the computer system. The full from of RAM is Random Access Memory. Information stored in RAM is electrically dependent and erasable. The full form of ROM is Read Only Memory. This is permanent memory and fixed in the processing part of the computer. Secondary memory is used to store data for a long time. Floppy Disk is the secondary memory device usually used to store data with the help of floppy disk drives. Hard Disk is fixed inside the computer as mass storage media. Magnetic Tape is also a memory device which is made with a plastic tape coated with magnetic substances. Computer case contains all the major components of a computer system. Printer is an output device that prints output on paper. MoDem is the device that can convert analog signal to digital and digital signal to analog. A scanner is a device that reads graphics and text data into a computer.
Oasis Radiant computer science Grade Four 43 Exercise 1. Fill in the blanks. a. All the parts connected to the computer are called …………….. b. ……………displays the result on the screen. c. The types of monitor are CRT and ………….. d. Keyboard is a popular …………device. e. The full form of CPU is ……………….. f. ………….unit is known as the brain of the computer. g. RAM is called …………….memory. h. ……………..is a device which converts analog signal into digital and digital signal into analog. 2. State whether the following statements are True or False. a. CPU is called Central Processing Unit. b. You can use Escape key to quit a task that you are performing. c. Ctrl key is used to enter text in uppercase. d. F1, F2, F3 etc are called numeric keys. e. ALU is the main part of the computer. f. There are two types of memory; they are primary and volatile memory. g. ROM is a temporary memory. h. The full from of RAM is Random Access Memory. i. Hard disk is fixed inside the computer. j. Magnetic tape is also called as primary memory. k. Printer is an output device. l. Mouse is a handheld pointing device. 3. Answer the following questions. a. What are computer peripherals? b. What is monitor? Write its types.
44 Oasis Radiant computer science Grade Four c. Name the various keys of keyboard. d. What is the use of function key and arrow key? e. Why do we use backspace key? f. What is Central Processing Unit? Name down the sections of CPU. g. What are the types of memory? h. What is primary and secondary memory? i. Write the types of ROM. j. Why is RAM called temporary memory? k. Write the various storage unit conversions. l. What is Disk Drive? m. What are Floppy Disk and Hard disk? n. What is printer? o. Define mouse and scanner. 4. Match the following: Hard disk hard copy output Floppy disk input device Printer small storage device Scanner large storage device Memory unit type of ROM PROM section of CPU 5. Project Work a. Draw the figure of various keys of keyboard in your copy. b. Draw the following pictures in your copy. i. Keyboard ii. Mouse iii. Scanner iv. Computer Case v. LCD Monitor
Types of Computer 6 Chapter How can you classify computer on the basis of model? How can you classify computer on the basis of size? Describe the types of computer. How can you classify computer on the basis of work?
46 Oasis Radiant computer science Grade Four 6 Types of Computer CHAPTER Computer is a very popular device and used for different applications. In a broad approach, we can divide computer into two types: general purpose computers and special purpose computers. But according to the brand, size and the model of computers, we can classify the computer on different bases. a. On the basis of size b. On the basis of work c. On the basis of brand d. On the basis of model A. On the basis of size Technology used in the computer system changes the size and processing speed of the computer. Early computers were very large in size. They were slow in processing. On the basis of size, computers are classified as a. Mainframe Computer b. Mini Computer c. Micro Computer Mainframe Computer High speed computer that is very large in size is mainframe computer. It can store huge amount of data. It can process the data with very high speed. We can work with multiple terminals using a single system. It is suitable to make server computer in networking system.
Oasis Radiant computer science Grade Four 47 Mini Computer Mini computers are medium in size which means, they are bigger than micro computers and smaller than mainframe computers. These are applicable to networking system. they are expensive than micro computers but have higher speed, storage and processing capacity. Micro Computer All the personal computers are micro computers. These computers are based on microchips. These are used in office and home. We can get various types of micro computers. They are super computers, laptop computers, palmtop computers, etc. B. On the basis of work Computers are made to solve a particular task. We can classify them into three types. a. Analog computer b. Digital computer c. Hybrid computer Analog Computer Computers based on the analog circuit are analog computers. They can measure the physical and continuous value. We can use this computer to measure the temperature, pressure and other physical value. For example: telephone billing machine, speedometer, etc.
48 Oasis Radiant computer science Grade Four Digital Computer Computers based on the digital signals is digital computers. These are the advanced electronic computers that accept the discrete value 0 and 1 to function. All the PCs and advanced model computers are the examples of digital computer. Hybrid Computer Computers which work on digital as well as analog computer system are Hybrid computer. It uses the analog and digital signals for data processing. Some parts of computer operate with analog and some with digital data. C. On the basis of brand We can classify the computers on the basis of manufacturing company and its features related to the design. There are three types of computer. i. IBM-PC ii. IBM compatible computer iii. Apple / Macintosh computer IBM Personal Computer IBM (International Business Machine) Corporation was established in 1942 in the USA. IBM started to manufacture mainframe computers in 1945. The computers manufactured by this company are called the IBM computers. These are more reliable, strong and of high speed processing computers.
Oasis Radiant computer science Grade Four 49 IBM Compatible Computer IBM compatible computers are the computers which are based on the IBM principle. These are manufactured by different companies. IBM compatible computers can perform entire work that the IBM computer can perform. Apple or Macintosh Computer In late 1970s, Apple Company was established in USA. It has the determination to develop different types of computers more advanced than IBM computers. Apple Macintosh computers are applicable to desktop publishing and graphic design works. D. On the basis of model We can classify the computers on the basis of model and the technology used by the computers. They are: i. XT Computer ii. AT Computer iii. PS/2 Computer Extra Technology (XT Computer) These are extra technology computers. These are based on the 8086 microprocessor. These are popular as Pentium models. Advanced Technology (AT Computer) These are Advance Technology computers which are faster than the XT computers. These computers used 80286, 80386 and 80486 Microprocessors.
50 Oasis Radiant computer science Grade Four PS/2 (Personal System - 2) Computer In early 1190s IBM developed another model of computers called Personal System – 2 (PS/2). A laptop computer is the example of PS/2. It is still popular in different model of laptop. Chapter Review On the basis of size, computers are classified as Mainframe Computer, Mini Computer and Micro Computer. Mainframe Computer is large in size. It has very high speed and it can store a huge amount of data. Minicomputers are medium in size which means, they are bigger than micro computers and smaller than mainframe computers. All the personal computers are Micro computers. Different types of computers on the basis of work are Analog Computer, Digital Computer and Hybrid Computer. The computer that measures the physical and continuous value is called Analog computer. Digital Computer is an advanced electronic computer that accepts the discrete value 0 and 1 to function. Hybrid Computer works on digital as well as analog computer system. International Business Machine Corporation was established in 1942 in the USA.