Computer Science Grade 9 Government of Nepal Ministry of Education, Science and Technology Curriculum Development Centre Sanothimi, Bhaktapur Computer Science Grade 9 Government of Nepal Ministry of Education, Science and Technology Curriculum Development Centre Sanothimi, Bhaktapur 2076 Publisher: Government of Nepal Ministry of Education, Science and Technology Curriculum Development Centre Sanothimi, Bhaktapur © Publisher Edition: 2076 BS (2020 AD) Printing: Janak Shikshya Samagri Kendra Limited Sanothimi, Bhaktapur Preface The curriculum and curricular materials are developed and revised on a regular basis with the aim of making education objective-oriented, practical, relevant and job oriented. It is necessary to instill the feelings of nationalism, national integrity and democratic spirit in students and equip them with morality, discipline and self-reliance, creativity and thoughtfulness. It is essential to develop in them the linguistic and mathematical skills, knowledge of science, information and communication technology, environment, health and population and life skills. It is also necessary to bring in them the feeling of preserving and promoting arts and aesthetics, humanistic norms, values and ideals. It has become the need of the present time to make them aware of respect for ethnicity, gender, disabilities, languages, religions, cultures, regional diversity, human rights and social values so as to make them capable of playing the role of responsible citizens. This textbook for grade nine students as an optional Computer Science has been developed in line with the Secondary Level Optional Computer Science Curriculum, 2074 so as to strengthen knowledge, Skills and competencies on computer literacy. It is finalized by incorporating the recommendations and feedback obtained through workshops, seminars and interaction programmes. The textbook is written by Mr. Sunil Kumar Gharti, Mr. Sushil Upreti and Mr. Bimal Thapa. In Bringing out the textbook in this form, the contribution of the Director General of CDC Dr. Lekha Nath Poudel is highly acknowledged. Similarly, the contribution of Prof. Dr. Shashidhar Ram Joshi, Dr. Dipendra Gurung, Ms. Pramila Bakhati, Mr. Nabaraj Paudel, Mr. Jagadish Bhatta, Mr. Dibakar Durdarshi is also remarkable. The content was edited by Mr. Yubraj Adhikari and Mr. Khil Narayan Shrestha. The language of this book was edited by Mr. Shankar Adhikari and Mr. Nabin Kumar Khadka. The layout of this book was designed by Mr. Khados Sunuwar . CDC extends sincere thanks to all those who have contributed in developing this textbook. Efforts have been made to make this textbook activity-oriented, interesting and learner centered Curriculum Development Centre welcomes constructive feedback. 2076 Curriculum Development Centre Sanothimi, Bhaktapur Contents S.N. Page No Unit 1.1 Computer Fundamentals 1 Unit 1.2 Types of Computer 12 Unit 1.3 Basic Architecture of Computer 22 Unit 1.4 Computer Hardware 29 Unit 1.5 Computer Software 57 Unit 2.1 Computer Graphics 77 Unit 3.1 Internet Technology 99 Unit 3.2 HTML (Hypertext Markup Language) 113 Unit 3.3 Cascading Style Sheets (CSS) 157 Unit 4.1 Computer Programming 174 Unit 4.2 Programming in QBASIC 186 Unit 1.1 Computer Fundamentals Introduction to Computer The modern world is called the age of science and technology. We cannot imagine life without science and technology. The modern world of advanced technology could not have been established without the development of computer technology. There is rapid development in computer. Computer is used in many different fields for varieties of tasks. It is used all over the world, no matter whether a country it is developed, developing or underdeveloped. Computer is also used in Nepal various fields like: business, bank, education, entertainment, scientific research, law, airlines, traffic control, etc. So, the computer is now affecting every sphere of human activities and leading to many changes. It has brought enormous changes in the world. Introduction The word "Computer" is derived from the Latin word "Computare" which means 'to calculate'. Nowadays, computer has become an indispensable part of our life. Computer is used in various places like: home, school, college, offices etc. Computer can perform complex mathematical calculations accurately in a short period of time. The modern computer has lots of capabilities like creating documents, videos, games, music presentation, etc. It can use AI (Artificial Intelligence) for understanding natural language, taking self-decision capabilities, analysing graphs and patterns, etc. Data is raw facts, concepts, or instructions in a formalized manner, which should be suitable for communication, interpretation, or processing by computer. Data is represented with the help of characters such as alphabets (A-Z, a-z), digits (0-9) or special characters (+,-,/,*,<,>,= ) Information is organized or classified data, which has some meaningful results for the receiver. Information is the processed data or meaningful results on which decisions and actions are based. 1 Computer Science : Grade 9 A computer is an electronic device that accepts raw data and instructions from users; processes it according to the given set of instructions, stores and gives meaningful information. Computer Working Principle of a Computer Computer is an electronic device that converts raw data into meaningful information carrying out various processes as instructed by the programme. Every computer has the ability to: a. Input: Enter raw data into the computer. b. Process: Process according to the given set of instructions to produce the required result. c. Output: Get meaningful information from the computer. d. Storage: Store data and information for future use. Characteristics of a Computer A computer is powerful and useful in all areas. The use of computer is increasing with time. The main features or characteristics of computer are described below: i. Automatic A computer is an automatic device. It can do tasks automatically as instructed by software. It can automatically control various devices attached with computer system. 2 Computer Science : Grade 9 ii. Speed A computer performs tasks accurately. The operations on data in computer are performed through electronic circuit according to given instructions. Computer can perform millions and billions of operations on data within a second. The speed of computer is measured in MegaHertz (MHz) or GigaHertz (GHz). The time taken to perform a task is measured in fraction of second. The smaller units of second are given below: Power of Unit of Time Meaning Part of Second 10 Millisecond (ms) One thousandth of second 1/1000 10-3sec. Microsecond(us) One millionth of second 1/1,000,000 10-6sec. Nanosecond(ns) One billionth of second 1/1,000,000,000 10-9sec. Picosecond (ps) One trillionth of second 1/1,000,000,000,000 10-12sec. Femtosecond (fs) One quadrillionth of second 1/1,000,000,000,000,000 10-15sec. iii. Accuracy A computer performs t4asks accurately. If data and instructions given to the computer are correct then it gives an accurate output. It means output totally depends on the given instructions and input data. If input data is incorrect then the output will be incorrect which is called GIGO (Garbage in Garbage out). iv. Storage Computer system consists of data storage unit. A computer has main storage and secondary storage. A large amount of data can be stored in secondary storage like hard disk, pen drive, CD/DVD, etc. for future use. The main memory (RAM) stores currently used data. Computer stores data in term of 0 and 1. The different units of storage in computer are given below: S.No. Memory Unit Description 1 Bit 1 Bit = 0 or 1 2 Nibble 1 Nibble = 4 Bits 3 Byte 1 Byte = 8 Bits Computer Science : Grade 9 3 4 Kilobyte (KB) 1 Kilobyte (KB) = 1024 Bytes 5 Megabyte (MB) 1 Megabyte (MB) = 1024 KB 6 Gigabyte (GB) 1 Gigabyte (GB) = 1024 MB 7 Terabyte (TB) 1 Terabyte (TB)= 1024 GB 8 Petabyte (PB) 1 Petabyte (PB) = 1024 TB 9 Exabyte (EB) 1 Exabyte (EB) = 1024 PB v. Diligence A computer can continuously work for a long time without losing its speed and accuracy. So it is called diligent device. It doesn’t get tired or bored or lazy while working. vi. Versatile A computer is a versatile device which means it is flexible. It has capability of performing different types of tasks like drawing paints, playing games, music, calculations, sending an e-mail, desktop publishing work, etc. in different field efficiently. So it is used in different fields to perform varieties of tasks. Application of Computer A computer is given great importance in every field of work. Nowadays, it is impossible to find where computer are not used. Computer and its technology are used in education, agriculture, industries, banking, engineering, scientific research and many more. The main applications of computer are described below: i. Education Nowadays, computer and Internet technology have changed the present education system. Computer technology can be used for visual illustration like smart classroom and distance learning education system. Today, school and colleges use computer in computer lab and multimedia to teach students. A teacher can teach by using computer- based presentations. Students can study various subject and complete assignment by using Internet. 4 Computer Science : Grade 9 Computer in Education ii. Communication A computer plays a key role in the field of communication. The Internet and computer are used to send and receive information. A computer uses various communication services like e-mail, video conferencing, net phone, chatting, Facebook, Twitter, Instagram, etc. Computer in Communication iii. Banking Sector A computer has brought revolution in the banking sector. The different services like accounting, customer records to update, bank statement etc. are performed by using computer in banking sector. ATM (Automated Teller Machine) allows 24 hours banking services to their customers so that they can withdraw money at any time. Computer Science : Grade 9 5 Computer in Banking Sector iv. Medicine A computer is used in scanning and diagnosing of various diseases through CT scan (Computed Tomography scan), ultrasounds, ECG (Electro Cardio Graph) etc.