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NIGERIAN ARMY UNIVERSITY, BIU BORNO STATE, NIGERIA FACULTY OF COMPUTING DEPARTMENT OF COMPUTER SCIENCE COS 101 INTRODUCTION TO COMPUTING LECTURE NOTE...

NIGERIAN ARMY UNIVERSITY, BIU BORNO STATE, NIGERIA FACULTY OF COMPUTING DEPARTMENT OF COMPUTER SCIENCE COS 101 INTRODUCTION TO COMPUTING LECTURE NOTE COURSE CONTENT - Brief History of Computing - Description of the basic components of a computer/computing devices - Input/output devices and peripherals - Hardware, software and human ware - Diverse and growing of computer/digital applications. - Information processing and its roles in society - The internet, its application and its impact on the world today. - The different areas/program of the computing discipline - The job specializations for computing professionals - The future of computing FIRST SEMESTER 3 UNIT COURSE  Dr. Manga Ibrahim COURSE MATERIAL COURSE TITLE: INTRODUCTION TO COMPUTING COURSE CODE: COS 101 DEPARTMENT OF COMPUTER SCIENCE NIGERIAN ARMY UNIVERSITY, BIU 2024 1  HISTORICAL OVERVIEW OF COMPUTER The computer as we know it today is most likely one of the great technological "triggers" for future change. In a short period since the "invention" of computer, its impact on our lives has been felt in a diverse way. Ranging from home to offices, the computer is rapidly becoming an indispensable computational tool. What is this device that has become so important, and how does it work? The answers lie in the history of its development, as we shall study in this course. 1.0 EARLY HISTORY OF COMPUTING The computer is relatively new but its development to its present stage is long. Computers were developed as a result of man’s search for fast and accurate devices to do things easier. Historically, Computer started as a mechanical counting and calculating devices, later as electromechanical devices, and presently as digital electronic devices. The development takes place in three (3) directions: i. Miniaturization – reduction of computer in size to become smaller. ii. Speed – making computer to be faster iii. Affordability – cost reduction The modern computer had its beginning with 19th century prominent mechanical devices which include Abacus, slide rule, Napier’s bones, Difference Engine, Hollerith Tabulating Machine, and others. The Abacus -2500 BC: Abacus was the first known calculating machine used for counting. It was made of beads strung on cords. The cords correspond to positions of decimal digits. The beads represent digits. Numbers are represented by beads close to the crossbar. Abacus was mainly used for addition and subtraction and later for division and multiplication. Fig. 1.1 Abacus The Slide Rule - 1633 AD: The Slide Rule was invented by William Oughtred. It was based on the principle that actual distance from the starting point of the rule is directly proportional to the logarithm of the numbers printed on the rule. The slide rule is embodied by the two sets of scales that are joined together, with a marginal space between them. The slide rule could perform multiplication and division by a method of addition and subtraction and be used for calculating numbers raised to powers. 2  Fig. 1.2 The slide Rule Napier’s Bones - 1614 AD The Napier’s Bones was the first system of algorithm invented by John Napier, a Scottish mathematician as an aid to a multiplication of large numbers. A set of bones consisted of nine rods, one for each digit 1 to 9 and a constant rod for the digit ‘0’. A rod is similar to one column of a multiplication table. John Napier invented the idea of logarithms (remember: if x = yz then logy x = z) and used this concept to develop a device known as Napier’s bones that managed to reduce the complexity of multiplication and division into the simpler operations of addition and subtraction. He did this by taking advantage of the fact that if a number is expressed in exponential form, multiplication can be carried out by adding the exponents (for example, 10 2 × 104 = 10(2+4), which is a simplified calculation of 100 × 10,000). Fig. 1.3 Napier’s Bone The Rotating Wheel Calculator - 1642 AD: The Rotating Wheel Calculator called Pascaline was developed by a French philosopher, Blaise Pascal, using simple components such as gears and levers. This is a predecessor to today’s electronic calculator. He was only 19 years old when he devised this model. The machine has 6 wheels each has a digit on it and 1 pointer. The first wheel to the right counted the units, the second 10s, the third 100s in that order. 3  Fig. 1.4 The Rotating wheel Calculator The Difference Engine - 1822 AD: The Difference Engine was built by Charles Babbage, the British mathematician, and engineer which mechanically calculated mathematical tables. The machine contains all the necessary elements of a modern computer and was very large. His Analytical Engine was the first machine able to receive instructions in the form of holes in paper punch cards and hence is considered as the first programmable machine. Also, the Analytical Engine was the first machine to support conditional program execution. Although he spent all his fortune and worked for nearly 40 years on the project, it was never completed. Babbage is called the father of today’s modern computer because his machine formed the basis on which modern computers were made. Sequel to this development, when Augusta Ada Byron, Lady Lovelace heard of Babbage’s idea for a new engine. She suggested to Babbage a plan for how the engine might work. This plan is regarded as the first computer program. So, Ada Lovelace was regarded as the first computer programmer. Fig. 1.5 The Difference Engine The Analytical Engine- 1830 AD This calculating machine was also developed by Charles Babbage in 1830. It was a mechanical computer that used punch-cards as input. It was capable of solving any mathematical problem and storing information as a permanent memory. 4 Fig.1.6 Analytical Engine Tabulating Machine - 1890 AD: A tabulating machine using punched cards that worked on electricity was designed by Herman Hollerith and was called the Hollerith Tabulating Machine. This electronic machine was able to read the information on the punched cards and process it electronically. The tabulator was used in processing census data of 1890 in the US by reading of holes on punched cards. Hollerith founded a tabulating machine company that changed to International Business Machine (IBM) cooperation in 1924. Fig. 1.6 Hollerith Tabulating Machine 2.0 THE 20TH CENTURY DEVICES: In the 1920s and ’30s, several new types of calculators were constructed. Some of the prominent 20th-century devices are: 1. Differential Analyzer: Vannerver Bush, an American engineer, developed an analog computer that he called a differential analyzer; the first calculator to solve differential equations, but its lack of precision prevented wider adoption. 2. Harvard Mark 1: In 1944, Howard Aiken, in an attempt to develop the machine that could help him in solving difficult differential equations, invented the Automatic sequence controller calculator called Mark 1, the world's first computer. It was an electromechanical machine, similar to Babbage’s engine in design and so was described as Babbage’s dream come true. Mark 1 was very huge based on relays and was not fast. 5  3. ENIAC: In 1946, the machine based on very high-speed vacuum tubes called Electronic Numerical Integrator and Calculator [ENIAC] was invented by John W. Mauchly. It was faster than Mark 1. ENIAC was described as the first general-purpose electronic computer and is often chosen as the main representative of vacuum tube computers now refer to as first-generation computers. ENIAC contained 18,000 vacuum tubes, weighed over 30 tons, occupied 1600 square feet of floor space, and required 100 kilowatts of power. Heat dissipation was a problem and the vacuum tubes were not very reliable; when one burned out, it had to be replaced. The ENIAC was much faster than the MARK I, capable of arithmetic operations in fractions of a second. One difficulty that the ENIAC and MARK I had was that their design used a decimal representation of numbers. John von Neumann, based on an idea by Claude Shannon, proposed that binary numbers would simplify the design of computers. 4. EDSAC: Subsequently, to improve on ENIAC, Mauchly and J. Presper Eckert developed a binary rather than a decimal electronic computer and was a stored program machine called Electronic Delay Storage Automatic Calculator [EDSAC] in 1949. EDSAC was based on Veneman’s idea to improve speed and flexibility. 5. UNIVAC: In 1951, Eckert -Mauchly put into service, the world’s first commercial computer called UNIVAC. It is a stored-program computer and handled numbers and alphabet characters. Moreover, in 1958, the breakthrough in computer miniaturization occurred, when Jack Kilby designed the first true integrated circuit, the major component of electronic circuitry. This enables makers of computers to cram more hardware components into small space into their machines and more data storage capacity. Another evolution in microchips technology occurred in 1971 when Marcian E. combined the basic elements of a computer on one tiny silicon chip, called a microprocessor. The personal computers; desktops and laptops that we use today were invented in the 1970s. 3.0 GENERATION OF COMPUTERS This occurs due to a change in technology used for building computers based on devices being used, hardware organization, and programming languages used. At present we have six prominent generations of computers. Every new generation has dramatic improvements that fundamentally changed the way computers operate compared to the previous one. These helped to develop smaller, cheaper, powerful, efficient, and reliable machines. First Generation Electronic Computers (1937-1953) The first generation of computers used vacuum tubes as the basic components for memory and circuitry for Central Processing Unit [CPU]. These tubes consumed a large amount of electricity and generate enormous heat that can cause the computer to malfunction. The features of the first-generation computers are: 1. the vacuum tube is the basic components for memory and Central Processing Unit circuitry 2. very large normally taking up entire rooms and so non-portable 3. consume a large amount of energy 6  4. generate a lot of heat 5. low in reliability due to slow input and output devices 6. very expensive because the vacuum tubes used and so, only large organizations can afford it 7. had limited memory size 8. It used machine language or 0s and 1s only, subroutines, and assemblers. Computers of this generation could only perform a single task at a time, and mainly batch processing operating system was used. The input was based on punched cards, magnetic tape, and paper tape, and output was displayed on printouts. The first multi-purpose, programmable, computing device was probably Charles Babbage's Difference Engine, which was never completed. A more ambitious machine was the Analytical Engine, designed in 1842, but unfortunately, it was only partially completed by Babbage. Some computers of this generation were: abacus (3000 BC), Pascaline (17th century), Punch cards (1890) for data input, output, and storage. UNIVAC, ENIAC, EDVAC, IBM701, IBM-650, are classic examples of first- generation computing devices. Fig. 3.1a: Vacuum Tube b: First Generation Computer (1937-1953) Second Generation of computers (1954-1962): The second generation of computers witnessed the vacuum tubes being replaced by transistors. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more compact in size, energy-efficient, and more reliable than their first- generation counterparts. The transistors also generated considerable heat that sometimes caused the computer to malfunction. But it was a vast improvement over the vacuum tube. Second- generation computers used punched cards for input and printouts for output. Magnetic cores were used as the primary memory and magnetic tape and magnetic disks as secondary storage devices. In this generation, computers moved from the use of machine language to assembly language and high-level programming languages like FORTRAN, COBOL, which allowed programmers to specify instructions in words. The computers used batch processing and multiprogramming operating system. 7 Fig. 3.2 a: Transistor b: Second Generation computer (1954-1962) The features of second-generation computers are: 1. The invention of transistors which replaces vacuum tubes 2. The transistor made computers smaller, less expensive, and increased calculating speeds. 3. Consumed less electricity as compared to first-generation computers 4. Generated less heat as compared to first-generation computers 5. Reliable in comparison to first-generation computers 6. Supported machine and assembly languages Memory technology was based on magnetic cores which could be accessed in random order Some computers of this generation were: IBM 1620, TADIC, IBM 704, IBM 7030, IBM 7094, CDC 1604, CDC 3600, UNIVAC 1108. Third Generation of computers (1963-1972): The computers of the third generation used Integrated Circuits (ICs) invented by Jack Kilby in place of transistors. Transistors were made smaller in size and placed on silicon chips, which dramatically increased the speed, efficiency, reliability of computers and made computers smaller in size. A single IC has many transistors, resistors, and capacitors along with the associated circuitry. In this generation, keyboards and monitors were used instead of punched cards and printouts. The computers were interfaced with an operating system that allowed remote processing, time-sharing, and multi-programming. High-level languages (FORTRAN-II TO IV, COBOL, PASCAL PL/1, BASIC, ALGOL-68, etc.) were used during this generation The features of third-generation computers are: 1. hundreds of transistors were replaced by integrated circuits (IC) on a silicon chip (LSI and VLSI) 2. This made computers even smaller and faster 3. Consumed lesser electricity 4. Generated less heat 5. More reliable in comparison to the previous two generations 6. Costly with lesser maintenance 7. Supported high-level languages such as BASIC, Pascal, C, COBOL, and Fortran Some computers of this generation were: IBM-360 series, Honeywell-6000 series, PDP (Personal Data Processor), IBM-370/168, TDC-316, Intel 4004, Intel 8008, etc. 8 Fig. 3.3 a: Integrated Circuit b: Third Generation computer (1963-1972) Fourth-generation computers (1972-1984): Fourth-generation computers used Large scale integrated circuits [LSI] and Very Large Scale Integrated [VLSI] circuits. VLSI circuits having about 5000 transistors and other circuit elements with their associated circuits on a single silicon chip made it possible to have microcomputers of the fourth generation. They are more powerful, compact, reliable, and affordable. As a result, it gave rise to the Personal Computer (PC) revolution, which eventually led to the development of the Internet. In this generation, time-sharing, real-time networks, distributed operating system were used. All the high-level languages like C, C++, DBASE, etc., were used in this generation. The features of the fourth generation are: 1. used Silicon Chips (Large scale integrated circuits) =LSI and VLSI 2. Very small size, entire processors will fit onto a single chip (microprocessor) 3. Very cheap, easily available, Portable, and reliable 4. The concept of the internet was introduced with great developments in the fields of networks 5. Pipeline processing and No AC required Some important events were: the development of the C programming language and the UNIX operating system, inventions of word processors, video games, laser printers, inkjet printers, spreadsheets, cell phones, Walkman, MS-DOS. Some computers of this generation were: DEC 10, STAR 1000, PDP 1, CRAY-11(Super Computer), CRAY-X-MP (Super Computer), APPLE 1, IBM PC, MACINTOSH, etc. Fig. 3.4a: Microprocessor b: Fourth generation computers (1972-1984) Fifth Generation computers (1983-1990): In the fifth generation, VLSI technology became ULSI (Ultra Large-Scale Integration) technology, resulting in the production of microprocessor chips having ten million electronic components. This generation is based on parallel processing hardware, allowing many processors to work on different parts of a single program, and AI (Artificial Intelligence) software. AI is an emerging branch in computer science, which interprets the means and methods of making computers think like human beings. AI includes Robotics, Neural Networks, 9 Game Playing, Development of expert systems to make decisions in real-life situations, Natural language understanding, and generation, etc. All the high-level languages like C and C++, Java,.Net, etc., are used in this generation, and CDROM, Windows programs, first 3D video games were invented. The features of fifth-generation computers are: 1. Based on ULSI technology due to advancement in Superconductor technology 2. The devices are based on true artificial intelligence and are still in their developmental stage 3. Development of Natural language processing to bridge the gap between computing and thinking. 4. Advancement in Parallel Processing 5. More user-friendly interfaces with multimedia features 6. Availability of very powerful and compact computers at cheaper rates 7. use more than one CPU for faster processing speed. 8. solve the highly complex problem including decision making, logical reasoning. Some computer types of this generation are Desktop, Laptop, NoteBook, UltraBook, ChromeBook, IBM PC-AT, Intel 80486, video toaster, etc. Fig. 3.5: IBM PC-AT 1984 Sixth Generation computers (1990-till date): Many of the developments in computer systems since 1990 reflect gradual improvements over established systems. These significant changes represent a transition to a new ``generation'' the sixgeneration. Some of the popular inventions are WWW, HTML, Web TV, DVD, YouTube, etc. Examples of computers in this generation are: Power Book by apple (1991), Pentium microprocessors by Intel (1993), Sun Ultra workstation (1996), and many more like core processor, etc. 4. WHAT IS A COMPUTER? A Computer is an electronic device, operating under the control of instructions stored in its memory unit, that can: accept data (input), manipulate the data according to specified rules (process), provide information (output) in a useful format, and store the results for future use. It is a kind of electronic machine that assists mankind to solve different types of problems. It can also be regarded as an automatic machine capable of processing the data and producing the information. Fig. 4.1: A typical computer Data: It is the collection of unstructured facts, figures & symbols that have not been processed by humans or with a computer, from which information and knowledge are derived. 10 Example: Names of students and their marks in different subjects listed in random order. Information: It is the data that is processed and presented in an organized manner. Example: When the names of students are arranged in alphabetical order, total and average marks are calculated & presented in a tabular form, it is information. Program: Set of instructions that enable a computer to perform a given task. Processing: is the method of converting the input data into the required output form with the help of the computer program and hardware. Functionalities of a Computer Any digital computer works as an Input-Process-output system and carries out the following functions/operations in sequence: 1. Input: Takes data as input and command from the input device to the computer. 2. Processing: it processes the data and converts it into a useful format. 3. Output: it generates the output which is displayed by the computer to the user, either hard copy or soft copy. 4. Storage: it stores the data/instructions in its memory and uses them as required inside or outside the computer. 5. Control all the above four steps. Advantages of Computers The following are certain advantages of computers. 1. High Speed: The computer is a very fast device that can perform millions of calculations in a few seconds (in a microsecond, nanosecond, and even the picosecond) as compared to a man. 2. Accuracy: Computers perform thousands of operations with 100% accuracy provided that the input is correct. 3. Storage Capability: A computer has much more storage capacity than human beings, that can store a large amount of data in small space such as images, videos, text, audio, etc. 4. Diligence: Unlike human beings, a computer can perform jobs for a long time obediently, free from monotony, tiredness, and lack of concentration. 5. Versatility: It can be used to solve multiple (tedious) tasks in various domains at the same time. 6. Reliability: A computer does exactly what it is told to do without human intervention. 7. Automation: A computer is an automatic machine that can perform a given task automatically under the control of a stored program. 8. Communication: A computer can connect to share resources. 9. Power: the larger the word length of a computer the more powerful it becomes 10. Paperless processing: data can be processed using computers instead of papers Disadvantages of Computers Though computers are intelligent machines: i. No IQ A computer cannot take any decision on its own. ii. It cannot correct any wrong instruction fed in by an operator, it is Garbage-In-Garbage- out iii. Dependency: It functions unless programmed; thus, it is fully dependent on humans. iv. A computer cannot decide how they are to be programmed or provide input. 11 v. A computer cannot implement their decisions or interpret their results. A child can easily tell the difference between a cat and a sheep while a computer cannot. vi. No Feeling: Computers have no feelings or emotions and so cannot make judgments based on feeling, taste, experience, and knowledge, unlike humans. 5. COMPUTER HARDWARE COMPONENTS A computer is made up of two constituents: hardware and software. The term hardware refers to all of the physical devices, or components, that a computer is made of. A computer is not one single device, but a system of devices that all work together. A typical computer system consists of five major categories of hardware components (devices): Processing devices, Secondary storage devices, Input devices main memory, and Output devices Fig. 5.1: Computer hardware The system unit is the core of a computer system. Usually, it's a rectangular box that houses many electronic components that process information. The most important of these components is the central processing unit (CPU), or microprocessor, which acts as the "brain" of your computer. Processing devices: These are the devices in the processing unit to interpret instructions, process data, and control the other devices. They include CPU, ALU, control unit, and main memory. The CPU: The central processing unit, or CPU, is the part of a computer that runs programs. The CPU consists of the Arithmetic Logic Unit (ALU) and the control unit. Fig 5.2: CPU ALU: It is where all arithmetic operations and logical functions are performed. The Main Memory / Primary Memory Units: It stores data, program instructions, internal results, and final output temporarily before it is sent to an appropriate output device. They are:  RAM (Random Access Memory) - Active, temporary.  ROM (Read-only Memory) - Permanent 12 RAM is a temporary storage device or primary workspace that stores information that the CPU uses while the computer is on. RAM is a memory that does not hold its contents without power. ROM is a special type of memory that can only be read and contents of which are not lost even when the computer is switched off. It typically contains the manufacturer’s instructions and ‘bootstrap loader’ whose function is to start the computer software operating, once the power is turned on. Input Devices: The component that collects the data and sends it to the computer is called an input device. They allow you to enter data, programs, commands, and user responses into a computer. Common input devices are the keyboard, mouse, scanner, microphone, and digital camera. Disk drives and optical drives can also be considered input devices because programs and data are retrieved from them and loaded into the computer’s memory. Keyboard: This is a peripheral device used to enter data, feed information to the system, or to communicate with the system. When you press a key on the keyboard, the action sends a signal to the system processing unit, the signal can make the character you typed appear on the screen, or it trigger a response based on the command issued by your input. Fig 5.3: Types of Keyboards a. 101 Key enhanced keyboard: It has one hundred and one keys on it. b. 104 Key windows keyboard: It has one hundred and four keys on it. c. Ergonomic keyboard: Normal keyboard d. Multimedia keyboard: provide media control to play mp3, CD, DVD. e. Cordless keyboard: The cordless keyboard is run on battery Features of a Keyboard Alphanumeric key: a-z, 0-9, punctuation keys, all keys associate with punctuation keys, parenthesis. Virtual keys: (arrow keys, function keys) Modifier or command keys: [SHIFT, Alternate (ALT), and Control (CTRL)] keys are special keys that modify the action of another key when pressed together. Each key on a standard keyboard has one or two characters. Press the key to get the lower character and hold Shift to get the upper characters. Some keyboard keys and their functions i. Enter key- to begin the next line, paragraph, or tell the computer to obey a command ii. Space bar- to insert spaces between words iii. Backspace – to delete characters to the left of the cursor iv. Caps lock- to notify the computer when to type upper case and when to type lower case letter v. Shift key – to type symbols located on the keyboard with two symbols on then The mouse: is an input device that is used to send messages (instructions) from the user to the computer system (applications packages). Most modern computers today have two buttons the left one is used to select objects and text and the right one is used to access menus. 13 Laptop computers use touchpads, buttons, and other devices to control the pointer. Hand-held use a combination of devices to control the pointer, including touch screens. A mouse performs the following functions  A mouse can be used to select icons on the Desktop  A mouse can be used to select commands in software applications.  It can be used to open a program, a folder, or a file.  A mouse can be used to move icons representing programs, folders, or files on the screen. Fig 5.4: Examples of Mouse The most common mouse actions are as follows: a) Pointing b) Clicking c) Double-clicking d) Right-clicking e) Dragging and dropping f) Highlighting/selecting Scanner: This is an input device, used to produce electronic copy (soft copy) of a hard copy (text or image) document. Scanners allow you to transfer pictures and photographs to your computer. A scanner 'scans' the image from the top to the bottom, one line at a time, and transfers it to the computer as a sequence of bits or a bitmap. The scanner does not recognize the content of the printed material it is scanning. Everything on the page (text and graphics objects) is converted into one bitmapped graphics image (bitmap), which is a pattern of dots. Fig. 5.5: Scanner Bar Code Reader: The barcode readers are used in places like supermarkets, bookshops, etc. A bar code is a pattern printed in lines of different thickness. The bar-code reader scans the information on the barcodes and transmits it to the computer for further processing. The system gives a fast and error-free entry of information into the computer. Fig.5.6: Bar Code and Reader Digital Camera: The digital camera is an input device mainly used to capture images, sound, or video. The digital camera takes a still photograph, stores it, and sends it as a digital input to the computer. It is a modern and popular input device. Fig. 5.7: Digital Camera Light Pen: A light pen is a pointing device shaped like a pen and is connected to a monitor. The tip of the light pen contains a light-sensitive element that, when placed against the screen, detects the light from the screen enabling the computer to identify the location of the pen on the screen. 14  Fig. 5.8: Light Pen Light pens have the advantage of ‘drawing’ directly onto the screen, but this can become uncomfortable, and they are not accurate. Touch Sensitive Screen: Touch Sensitive Screen is a type of display screen that has a touchsensitive panel. It is a pointing device that enables the user to interact with the computer by touching the screen. You can use your fingers to directly touch the objects on the screen and the screen senses the touch and communicate the object selection to the computer. Fig. 5.9: Touch Sensitive Screen Fig. 5.10: MICR Cheque Magnetic Ink Character Recognition (MICR): MICR is widely used by banks to process cheques. Human readable numbers are printed on documents such as cheque using special magnetic ink. The cheque can be read using a special input unit, which can recognize magnetic ink characters. This method eliminates manual errors. It also saves time, ensures security and accuracy of data. Magnetic Reader: Magnetic reader is an input device that reads a magnetic stripe on a card. It is handy and data can be stored and retrieved. It also provides quick identification of the card’s owner. All the credit cards, ATM cards (banks), petro cards, etc. stores data in a magnetic strip which can be read easily by the magnetic reader Fig. 5.11: Magnetic Reader Optical Character Recognition (OCR): The OCR technique permits the direct reading of any printed character like MICR but no special ink is required. With OCR, a user can scan a page from a book. The computer will recognize the characters on the page as letters and punctuation marks, and stores. This can be edited using a word processor. 15 Fig. 5.12: OCR Sheet Optical Mark Reading and Recognition (OMR): In this method, special pre-printed forms are designed with boxes that can be marked with a dark pencil or ink. Such documents are read by a reader, which transcribes the marks into electrical pulses that are transmitted to the computer. They are widely used in applications like objective type answer papers evaluation in which a large number of candidates appear, timesheets of factory employees, etc. Fig. 5.13: OMR Reader Smart Cards: This input device stores data in a microprocessor embedded in the card. This allows information, which can be updated, to be stored on the card. These data can be read and given as input to the computer for further processing. Most of the identification cards use this method to store and retrieve vital information. Fig. 5.14: Smart Cards Notes Taker: Notes taker is a device that captures natural handwriting on any surface onto a computer. Using an electronic pen, the notes taker displays the user’s handwritten notes, memos, or drawings on the computer, and stores the image for future use. Fig. 5.15: Notes Taker Microphone: The microphone serves as a voice input device. It captures the voice data and input to the computer. Using the microphone along with speech recognition software can offer a completely new approach to input information into your computer. 16 Speech recognition programs, although not yet completely exact, have made great strides inaccuracy as well as ease of use. The voice-in or speech recognition approach can almost fully replace the keyboard and mouse. Speech recognition can now open the computer world to those who may have been restricted due to a physical handicap Fig. 5.16: Microphone Output Devices: Output is anything that comes out of a computer. An output device is capable of presenting information from a computer. There are many output devices attached to computers. But the monitors and printers are commonly used output devices. Disk drives and CD recorders can also be considered output devices because the system sends data to them to be saved Monitors: The monitor is a commonly used output device, sometimes called a Visual Display Unit(VDU). It provides a visual display of data. Monitors are connected with the computer and are similar in appearance to a television set. Fig. 5:17 a) CRT Monitor b) LCD Monitor c) Laptop screen The monitors work like a television screen and also look alike. Most desktop computers use a monitor with a cathode-ray tube or liquid crystal display. Most notebooks use a liquid crystal display monitor. CRT is a vacuum tube used as a display screen in a video terminal or TV. CRT has higher radiation, consumes more energy to operate, and it also big compare with LCD. LCD is a flat panel display that uses liquid crystals. Although almost exclusively used in laptops, LCD technology is also the most popular flat panel desktop monitors. With their low power consumption, low radiation, and space-saving footprint, flat panels are expected to eventually become the standard and gradually replacing the CRT. The screen resolution can be adjusted by the user to control the screen's display. The smallest dot that can be displayed is called a pixel (picture element). The number of pixels that can be displayed vertically and horizontally gives the resolution of the monitor. The resolution of the monitor determines the quality of the display. Some popular resolutions are 640 x 480 pixels, 800 x 600 pixels and 1024 x 768 pixels. A resolution of 1024 x 768 pixels will produce a sharper image than 640 x 480 pixels Printers: The printer is an output device that prints text or images on paper or other media. By printing, you create what is known as a ‘hard copy’. There are different kinds of printers, which vary in their speed and print quality. The two main types of printers are impact printers and non- impact printers. 17  Fig. 5.18 Types of Printers Impact printers include all printers that print by striking an ink ribbon. Impact printers use a print head containing several metal pins that strike an inked ribbon placed between the print head and the paper. Line printers, dot matrix printers are some of the impact printers. Characteristics of Impact Printers 1. In impact printers, makes physical contact with the paper to produce an image 2. Due to being robust and low cost, they are useful for bulk printing and printing multiple copies 3. They are mechanical and tend to be slow, very noisy, and do not support transparencies. Non-impact printers are much quieter than impact printers as their printing heads do not strike the paper. Non-impact printers include laser printers, inkjet printers, and thermal printers. Characteristics of Non-Impact Printers 1. Non-impact printers are faster than impact printers because they have fewer moving parts. 2. Have the ability to change typefaces automatically but cannot print multipart forms. 3. These printers usually support the transparencies and can produce high-quality graphics Line Printer: Line printers are high-speed printers capable of printing an entire line at a time. A line printer can print 150 lines to 3000 lines per minute. The limitations of line printer are they can print only one font, they cannot print graphics, the print quality is low and they are noisy to operate. But it can print a large volume of text data very fast compared to the other printers. It is also used to print on multipart stationaries to prepare copies of a document. Fig. 5.19a) Line Printer b) Dot Matrix c) Thermal Printer d) Laser Printer e) Inkjet Printer Dot Matrix Printer: The most popular serial printer is the dot matrix printer. It prints one line of 8 or 14 points at a time, with the print head moving across a line. Dot-matrix printers work like a typewriter transferring ink from a ribbon to paper with a sequence or 'matrix' of tiny pins. They are normally slow. The printing speed is around 300 characters per second. It uses multipart stationaries to prepare copies of a document. Thermal Printer: Thermal printers are printers that produce images by pushing electrically heated pins against special heat-sensitive paper. They are inexpensive and used widely in fax machines and calculators. Thermal printer paper tends to darken over time due to exposure to sunlight and heat. So, the printed matters on the paper fade after a week or two. It also produces 18 a poor-quality print. Laser Printers: Laser printers use a laser beam and dry powdered ink to produce a fine dot matrix pattern. It can produce a very good quality of graphic images. One of the chief characteristics of laser printers is their resolution – how many dots per inch (dpi) they lay down. The available resolutions range from 300 dpi at the low end to around 1200 dpi at the high end. Inkjet Printers: Inkjet printers use colour cartridges that combine magenta, yellow and cyan inks to create colour tones. A black cartridge is also used for crisp monochrome output. Inkjet printers work by spraying ionizing ink at a sheet of paper. Magnetized plates in the ink’s path direct the ink onto the paper in the described shape. Speakers: The computer is an electromechanical device that produces voice output (audio data). Speaker serves as a voice output device. Using speakers along with speech synthesizer software, the computer can provide voice output. Voice output has become very common in many places like airlines, banks, automatic telephone inquiry system, etc. Users can also hear music/songs using the voice output system. Fig. 5.20: Speakers Plotters: Apart from the output devices like printers, plotters are also used to produce graphical output. Although printer output is very convenient for many purposes, the user needs to present the information graphically to understand its significance. Projector: A projector is an optical output device that takes (projects) images or slides generated by a computer onto a projection screen. This surface or a projection screen, may be white screen or sometimes a wall. The advantages of are; Projectors may be used as a cheaper alternative to a television or monitor in large gatherings e.g. in schools, and at home to see the movies etc. The applications of Projectors include: - (a) could be used to demonstrate a presentation on a big screen in a classroom or a conference room for describing a topic, (b) in Companies for meeting and conference purposes etc. Fig. 5.21: Projector Storage Devices The computer may need to store data, programs, etc. in a computer-readable medium. This is called secondary storage. Secondary storage is a type of memory that can hold data for long periods, even when there is no power to the computer. Programs are normally stored in secondary memory and loaded into main memory as needed. Important data, such as word processing documents, payroll data, and inventory records, is saved to secondary storage as well. Secondary Memory is also termed as ‘auxiliary’ or ‘backup’ storage, it is typically used as a supplement to main storage. It is much cheaper than the main storage and stores a large 19 amount of data and instructions permanently. Hardware devices like magnetic tapes, Floppy Disk, Hard Disk, Optical disks, Compact Disk (CD), Digital Versatile Disk (DVD), and Blu-ray Disc (BD) fall under this category. The average time required to reach a storage location and obtain its contents is called its access time. In electromechanical devices with moving parts such as disks and tapes, the access time consists of a seek time required to position the read-write head to a location and transfer time required to transfer the data to or from the device. Hard Disk: Hard disk is a magnetic disk with high speed rotating surfaces coated with a magnetic recording medium, on which you can store computer data. The hard disk is a direct- access storage medium to store and retrieve data randomly. When writing data, a write head magnetizes the particles on the disk surface as either north or south poles. When reading data, a read head converts the magnetic polarisations on the disk surface to a sequence of pulses. The read and write heads are generally combined into a single head unit. There may be more than one read/write head. Data is arranged as a series of concentric rings. Each ring (called a track) is subdivided into several sectors, each sector holding a specific number of data elements (bytes or characters). Fig. 5.22: A track subdivided into sectors The smallest unit that can be written to or read from the disk is a sector. Once a read or write request has been received by the disk unit, there is a delay involved until the required sector reaches the read/write head. This is known as rotational latency, and on average is one half of the period of revolution. The storage capacity of the disk is determined as (number of tracks * number of sectors * bytes per sector * number of reading/write heads) Thus, the data is stored as magnetized spots arranged in concentric circles (tracks) on the disk. Each track is divided into sectors. The arrangement of tracks and sectors on a disk is known as its ‘format’. High data rates demand that the disk rotates at a high speed (about 3,600 rpm). As the disk rotates read/write heads move to the correct track and fetch the desired data. Fig. 5.23: Hard Disk Drive The storage capacity of a hard disk can be Gigabytes (GB), i.e. thousands of Megabytes of information. 20 Magnetic Tape: A recording medium consisting of a thin tape with a coating of a fine magnetic strip, used for recording digital data. The tape itself is a strip of plastic coated with a magnetic recording medium. Fig. 5.24: Magnetic Tape Reader Data is stored in frames across the width of the tape. The frames are grouped into blocks or records which are separated from other blocks by gaps. Magnetic tape is a serial access medium, similar to an audio cassette, and so data cannot be randomly located. This characteristic has prompted its use in the regular backing up of hard disks. Floppy Disk: The floppy drive uses a thin circular disk for data storage. It is a thin, soft magneticcoated disk contained in a flexible or semi-rigid protective jacket. The disk rotates at 360rpm. A read/write head makes physical contact with the disk surface. Data is recorded as a series of tracks subdivided into sectors. The floppy disks are usually 3.5" in size and can hold 1.44 MB of data. Once data is stored on a floppy disk it can be ‘write protected’ by clicking a tab on the disk. This prevents any new data from being stored or any old data is erased. Disk drives for floppy disks are called floppy drives. Floppy disks are slower to access than hard disks, have less storage capacity, less expensive, and are portable and accessed randomly. Fig. 5.25: Floppy Disk Optical Disk: Optical disks are a storage medium from which data is read and to which it is written by lasers. The optical disk is a random-access storage medium; information can be easily read from any point on the disk. CD-ROM stands for Compact Disk - Read-Only Memory. Fig. 5.26: Compact Disk It is now possible to have CD-ROMs where tracks of information can be written onto them by the user. These are called read/write CD-ROMs and these are becoming a popular and cheap method for storage. Removable Storage and/or Disk Drives - All disks need the drive to get information read - and put information on the disk - or write. Each drive is designed for a specific type of disk whether it is a CD, DVD, hard disk, or floppy. 21  Fig 6.27: Storage devices Hard disks store the majority of information on today's modern computer. Information can be stored and deleted as necessary. As files get larger the speed that hard disks can read and write becomes more important. Digital flash drives work slightly differently as they use memory cards to store information so there are no moving parts. Digital cameras also use Flash memory cards to store information, in this case, photographs. Handheld devices use digital drives and many also use removable or built-in memory cards. 6. COMPUTER SOFTWARE Software refers to various kinds of programs used to operate computers and related devices to causes the hardware to function in the desired way. The software needs to be accessed before it can be used. There are many terms used for the process of accessing software including running, executing, starting up, opening, and others. The basic difference between the hardware and software is just the same as that exists between TV and TV studio. Without a TV studio (software) from where the programs are telecast, the TV (Hardware) is a dead machine. Software Categories: Software can be classified into two categories: Fig. 6.1: Software Categories System Software: System software is the collection of programs designed to operate, control, and extend the processing capabilities of the computer. These programs provide the environment to run the application programs and are a necessity for proper functioning. Users do not interact with the system software as it works in the background. The three major classes of system software are; 1. Operating System 2. Translators 3. Utility programs Fig. 6.2: System Software Utility Software: Utility software, designed to manage the operating system, support the computer hardware, and directly performing services that benefit ordinary users. Utility software 22 helps to manage, maintain, and control computer resources. Some have been integrated into operating systems such as file manager, disk cleaner, backup, disk petitioner, launcher applications, network managers, etc. Antivirus software, as the name suggests, helps to protect a computer system from viruses and other harmful programs. Backup software helps in the creation of a backup of the files on your hard disk drive of a computer. Backup software helps you copy the most important files on a disk and use it to restore the entire disk in the event of data failure of the selected file in the event of accidental deletion. Translators: Computers can understand instructions only when they are written in their language, the machine language. Translator a program designed to translate instructions written in any other language into machine language so that computers can execute them. Their translators are; compilers, assemblers, and Interpreters. 7. OPERATING SYSTEM (OS): The most important type of system software is the operating system. An operating system is an integrated set of specialized programs that are used to manage the overall operations of a computer. It serves as the interface between the computer hardware, the software, and the end- user, and allows a user to run other applications on a computing device. The primary goals of the O. S. are mainly to optimize resources and providing a user-friendly environment. It acts as manager of resources such as CPU time, memory space, file storage, I/O devices and allocates resources among the various programs optimally competing for them. Every computer must have an operating system to run other programs and ensure that available resources are equally shared. Examples of Operating Systems are Mac-OS, MS-DOS, UNIX, Windows O.S. LINUX, Apple Macintosh, and Android O.S. Windows O.S. is an operating system with a graphical user interface (icons, pictures, and menus) instead of text; uses a mouse as well as a keyboard as an input device) The Versions are Windows 98, Windows Me, Windows NT, Windows 2000, Windows XP, Windows Server 2003, Windows Vista, Windows 7, etc. O. S. programs: O. S. consists of several programs. They are categorized into control programs for managing resources and service programs for providing services. Scheduling strategies While executing a job, the OS reads the next job from memory into a storage area on the disk and outputs a printout of a previous job from disk to the printer. Spooling allowed the CPU to choose a particular job for execution leading to the concept called Job Scheduling. Scheduling is the method by which processes are given access to system resources. The strategies used are: 1. Multiprogramming system: In multiprogramming, memory is divided into many partitions. The O. S. keeps two or more processes that are runnable in memory simultaneously by sharing a single processor. It selects a job from the ready state and starts executing it. When that job needs to wait for some external event the CPU is switched to another job to maximize CPU usage (eliminate idle time). Multiprogramming allows many programmes to load their programs in different partitions. 23  2. Time-sharing: Multiprogramming was followed by the time-sharing concept. In Time- sharing, the running task is required to relinquish the CPU, either voluntarily or by an external event to another task. This is to allow several programs to execute simultaneously. This is known as a multitasking system. It is a method by which multiple processes share common processing resources by switching between them with a fixed time for each program. In the next cycle, the program that had been considered earlier was taken once again. This process continued until all the programs were executed. A computer with a single CPU uses multitasking to solve problems by scheduling which task may run at any given time and when another waiting task gets a turn. The act of reassigning a CPU from one process to another is called a context switch. Context switch involves two processes one leaves the running state and another enters the running state. A computer with more than one CPU is called a multiprocessing system. It is where multiple processors run multiple processes at the same time, which creates physical parallelism. 3. Major Features of the Operating System: based on the number of users, and O. S. can be Single user: only one user can operate the system at a time e.g. MS-DOS. Multi-user O.S.: More than one user can operate the same system simultaneously and is based on the concept of time-sharing e.g. Unix O.S. Functions of Operating System: Today, most operating systems perform the following important characteristics: 1. Process management: It controls the jobs submitted to the CPU. Several algorithms are used to allocate the job to the processor e.g. First In First Out; based on queuing, Shortest Job First: select the process that has the shortest expected processing time. Round Robin: Jobs are assigned processor time in a circular method; Based On Priority: In this method, each job is assigned a Priority 2. Memory management: It Keeps track of the primary memory, to check what part is in use, by whom, what part is not in use, etc. It manages the allocation of main memory and other storage areas to the system programs as well as user programs and data when a process or program requests it. 3. Device (I/O) management: It manages the coordination and assignment of different Input and Output devices while one or more programs are executed. Only the O. S. is empowered to instruct the hardware to make an allocation or de-allocation, which process gets the device, when, and for how much time. 4. File management: It allows all files to be easily changed and modified through the use of text editors or some other file manipulation routines. 5. Job scheduling: It determines and maintains the order in which jobs are to be executed in the computer system. 6. Interpretation of commands and instructions. 7. Facilitates easy communication between the computer system and the computer operator 8. Monitor performance: it supervises records delays between the request for a service and from the system. 9. Security Management: The O. S. provides some levels of securities to the user like the File access, System-level, and Network level to safeguard against unauthorized access. To 24  access the files created by other people, you should have the permission, password in a multi-user environment. 8. APPLICATION SOFTWARE: An Application Software consists of programs designed to solve a user problem in a particular area. Users interact with the application software while doing their different activities. It is used to accomplish specific tasks rather than just managing a computer system. Such as a program to list stock items for a particular shop, or a program designed to give a forecast of the weather; the list is endless. These programs are written in different languages such as BASIC or C or by using database packages like dBase, Oracle. Example: Payroll, Billing, Railway Reservation, etc. Application software is in turn, controlled by system software that manages hardware devices. Application software is classified into customized applications and general-purpose application programs. The General-Purpose Application Programs: These packages are developed to suit the needs of research workers /scientists in different fields. These packages are categorized as word processor (typing letters), spreadsheet (financial info), database (inventory control and address book), data analysis, graphics program, internet browser, email, and many others, etc. The commonly used application software packages are a word processor, spreadsheet, database management system, and graphics. Word processing software. This software enables you to create, edit, format, store and print text and graphics. Word processors are used in offices (to prepare letters, memos, project reports, minutes), in publishing (books), by journalism (media houses to produce newspapers and magazines), and in education (to prepare test and study materials). Some of the commonly used word processors are Microsoft Word, WordStar, WordPerfect, word pad, etc. Some Basic Features of word processors Word processors provide the following basic features: Insert text: Allows you to insert text anywhere in the document. Delete text: Allows you to erase characters, words, lines, or pages unlike crossing out on paper. Cut and paste: Allows you to remove a part of the text from one place in a document and insert it somewhere else. Copy: Allows you to duplicate a section of text. Page size and margins: Allows you to define various page sizes and margins, and the processor will automatically readjust the text so that it fits. Search and replace: Allows you to search for a particular word or phrase and replace it with another. Word wrap: The word processor automatically moves to the next line once the current line is full Print: Allows you to send a document to a printer to get a hardcopy. Spreadsheet software is the computer equivalent of a paper worksheet to organize numeric data in a tabular form. It provides many mathematical, financial & statistical functions, used in many businesses, scientific and engineering environments for analyzing data, calculations, organizes data in tabular form, and creation of graphics and charts. A spreadsheet consists of a grid made from columns and rows. Examples of spreadsheet programs are: Lotus 1-2-3, Corel's QuattroPro, MS Excel 25 Database Applications: A Database is a collection of related information about a particular subject (person, place, or thing) stored in a way that can easily be accessed, managed, and updated. Such as Computerized banking system, Automated Teller Machine, Airlines, and Railway reservation system, etc., are some of the database applications. The common Characteristics of Database include: Self-describing, Data exists permanently, multiple users can access the same data, and Data security protects the data from unauthorized access with the help of the passwords. Many software is used as Database Management Systems. Example: MS- Access, ORACLE, MySQL, etc. Relationship between Hardware and software 1. Hardware and software are mutually dependent on each other. 2. Both of them must work together to make a computer produce a useful output. 3. The software cannot be utilized without supporting hardware. 4. Hardware without a set of programs to operate upon cannot be utilized and is useless. 9. TYPES OF COMPUTER. Classification of the electronic computers may be based on either their principles of operation or their configuration. By configuration, we mean the size, speed of doing computation, and storage capacity of a computer. Computers can be broadly classified by their size, speed, and computing power (performance) into; i) microcomputers ii) Minicomputers iii) mainframe computers and iv) supercomputers. 1. Micro Computers These are the smallest range of computers having less storing space and processing speed. They are also called “computer of a chip” because its entire circuitry is contained in one tiny chip also called a microprocessor or CPU. These computers are also known as “Personal Computers”. Businesses use personal computers for word processing, accounting, desktop publishing, and running spreadsheet and database management applications. At home, the most popular use of personal computers is playing games and surfing the Internet. A microcomputer is further categorized into the following types: - a) Workstations b) Desktop c) Tablet PC d) Laptops e) PDAs a) Workstation: Workstation is desktop computers used for engineering or graphic applications; Computer-Aided Design (CAD), desktop publishing, software development, and other high-quality graphics capabilities. They have more processor speed than that of personal computers, high-resolution graphics screen, a large amount of RAM, inbuilt network support, a graphical user interface, and have mass storage device such as a disk drive. 26 Fig. 9.1: Workstation b) Desktops (Personal Computer): PCs are single-user portable machines easier to use and more affordable than workstations. Desktop computers are small enough to fit on top of a desk, yet they are too big to carry around. These machines are used for word processing, spreadsheets (excel), and small database applications. At home, the most popular use of personal computers is playing games and surfing the Internet. Examples: Dell, Hewlett- Packard, Compaq Presario, etc. Fig.9.2: Personal Computer c) Tablet PC is a kind of microcomputer that offers the newest development in portable computers. It is designed to function more like a portable writing tablet including handwriting recognition, voice, and fingerprint authentication. Fig.9.3: Tablet computers d) Laptops: also called notebook computers are similar in operation to desktops, laptop computers are miniaturized and optimized for mobile use. Laptops run on a single battery or an external adapter that charges the computer batteries. They are enabled with an inbuilt keyboard, touch-pad acting as a mouse, and a liquid crystal display (LCD) as a screen. Its portability and capacity to operate on battery power have served as a boon for mobile users. Laptop computers can be fit into a bag or briefcase but it more expensive than desktop computers. Examples: HP, Dell Inspirons, Apple, etc. Fig. 9.4: Laptop Computer c) Personal Digital Assistants (PDAs): It is a handheld computer known as a palmtop or smartphones. It has a touch screen and a memory card for storage of data, used as portable audio 27 players, and smartphones. Most of them can access the Internet using Bluetooth or Wi-Fi communication and it has communication capabilities. Examples: RIM’s Blackberry. Fig. 9.5: Personal Digital Assistants 2. Minicomputer: It is a midsize multi-processing system capable of supporting up to 250 users simultaneously. They are lower to mainframe computers, in terms of speed and storage capacity, and cost. Fig. 9.6: Minicomputer 3. Mainframe: The mainframe is expensive, very large, and capable of supporting even thousands of users simultaneously. They are used to process a large amount of data quickly at very high speeds (million instructions per second). Mainframe executes many programs concurrently and supports many simultaneous executions of programs at banks, airlines, and railway reservation systems, aerospace companies doing complex aircraft design, etc. Fig. 9.7: Mainframe 4. Supercomputer: Supercomputers are the mightiest, the fastest yet, the most expensive computers currently available. Supercomputers process billions of instructions per second and are employed for specialized applications that require an immense amount of mathematical calculations. For example, weather forecasting, scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (petrochemical prospecting), stock analysis, special effects for movies, and even sophisticated artworks. 28 Fig. 9.8: Supercomputer Classification based on Principles of Operation Based on the principles of operation, computers are classified into three types; analog computers, digital computers, and hybrid computers. Analog Computers: Analog Computer is a computing device that works on a continuous range of values. The analog computers give approximate results since they deal with physical quantities that vary continuously. It generally deals with physical variables such as voltage, pressure, temperature, speed, etc. the analog devices include a barometer, speedometer, fuel dispenser, mustimeter, etc. Digital Computers: On the other hand, a digital computer operates on digital data such as numbers. It uses a binary number system in which there are only two digits 0 and 1. Each one is called a bit. The digital computer is designed using digital circuits in which there are two levels for an input or output signal. These two levels are known as logic 0 and logic 1. Digital Computers can give results with more accuracy and at a faster rate. Hence digital computers have increasing use in the field of design, research, and data processing. Digital computers are made for both general purpose and special purpose. A special-purpose computer is one that is built for a specific application. General-purpose computers are used for any type of application. It can store different programs and do the jobs as per the instructions specified in those programs. Most of the computers that we see fall into this category. Hybrid Computers: A hybrid computing system is a combination of desirable features of analog and digital computers. It is mostly used for automatic operations of complicated physical processes and machines. Nowadays analog-to-digital and digital-to-analog converters are used for transforming the data into a suitable form for either type of computation. For example, in the hospital’s automated intensive care unit, analog devices might measure the patient’s temperature, blood pressure, and other vital signs. These measurements which are in analog might then be converted into numbers and supplied to digital components in the system. These components are used to monitor the patient’s vital signs and send signals if any abnormal readings are detected. Hybrid computers are mainly used for specialized tasks. 10. AN OVERVIEW OF COMPUTER ORGANIZATION Computers are often compared to human beings since both can accept data, store, work with it, retrieve and provide information. The main difference is that human beings can perform all of 29 these actions independently. While a computer requires a program to perform an assigned task. A Computer system is a set of physical equipment (hardware) and appropriate programs (software) logically connected and working together to meet the desired need. The hardware components include input devices, processors, storage devices, and output devices. The software items are programs and operating aids (systems) so that the computer can process data. Fig. 10.1: Components of a computer system In a nutshell, if you use a desktop computer as an example you might already know that there is no single part called the “computer.” A computer is a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. Software, on the other hand, refers to the instructions, or programs. Functional Units of a Computer System A computer system consists of five major categories of hardware components (devices): 1. Processing devices ii) Primary memory iii) Secondary storage devices iv) Input devices 2. Output devices Input devices: A computer uses input devices to accept the data and program. Input devices allow communication between the user and the computer e.g. keyboard, mouse, light pen, touch screen, etc., Output devices: These devices take machine coded output results from the processor and convert them into a form that can be used by human beings e.g. monitors and printers. Processing devices: CPU is the brain of any computer system that takes all major decisions, and all sorts of calculations. It consists of arithmetic and logic units, control unit, and internal memory (registers). The control unit of the CPU coordinates the action of the entire system. The Control Unit controls all the hardware operations. The arithmetic and logic units performing addition, subtraction, division, and multiplication as well as some logical operations. The instructions and data are stored in the main memory (RAM) so that the processor can directly fetch and execute them. While between any two components of the computer system, there is a pathway called a bus which allows for the data transfer between them. Memory devices: The computer stores the program and data that are currently being used in the main memory (RAM). The main memory holds data and programs only temporarily. Secondary storage devices can hold more storage than the main memory and are much less expensive. 30 Storage capacities and file sizes are measured from lowest to highest in: bits, bytes, kilobytes (KB), megabytes (MB), gigabytes (GB), terabytes (TB). Unit Size Equivalent to Byte (B) 8 Bits One character Kilobyte (KB) 1,024Bytes ½page of plain text Megabyte (MB) 1,024 KB 700 pages of plain text or 1 graphic Gigabyte (GB) 1,024 MB A set of encyclopaedias Terabyte (TB) 1,024GB A bookstore full of books Main Types of Storage Media Internal hard disk: This is a primary storage device with the highest storage capacity, where the operating system and users’ files are stored. When you install new applications, they are copied to your internal hard disk. External hard disk: This is the hard disk that used, to back up data. CD: Compact Disc - Read Only Memory drive look like music CDs but contain computer data instead of music, usually hold up to 700 MB of data. DVD: Digital Versatile Disc, can store more data and also transfers data to the computer far faster than CD. It stores up to 4.37 GB of data. Blu-ray: It is similar to DVD, used for recording and playing back high-definition video and for storing large amounts of data up to 25 GB of data. USB flash drive: USB flash drives are cheap and portable storage device in a range of sizes. Memory card: This is a form of storage often used in devices such as digital cameras, mobile phones, music players, video game etc. Online file storage: Virtual or cloud storage that hosts user files on the Internet. Users can upload files and can then access them over the Internet from a different computer, tablet, smart phone or other Internet-connected device. 11. ROLES OF COMPUTERS IN A SOCIETY: In this digital age of information technology, it has become a necessity for everyone to know about computers. This is based on the fact that the problems that we must solve are no longer solvable without the aid of computers. The application of computers in the society has led to many changes in education, government, health, homes, industry, law, medicine, scientific research, social service, and even arts like music, movies, and paintings. Computers at home: Many homes have multiple computers used for Internet communication, shopping, business, entertainment, schoolwork, and finances. Business: A computer has a high speed of calculation, diligence, accuracy, reliability, or versatility which has made it an integrated part in all business organizations for; payroll calculations, budgeting, sales analysis, financial forecasting, managing employee database, maintenance of stocks, etc. Banking: Today, banking is almost totally dependent on computers. Online accounting facilities, including checking current balance, making deposits and overdrafts, checking interest charges, shares, and trustee records are computer-based. ATMs that are completely automated are making it even easier for customers to deal with banks. 31 Insurance: Insurance companies, finance houses, and stockbroking firms are widely using computers for maintaining a database of all clients with information showing: procedure to continue with policies, starting date of the policies, next due instalment of a policy, maturity date, interests due, survival benefits and bonus Education: Computer literacy is required at all levels in providing a lot of facilities in the education system. The computer provides a tool in the education system known as CBE (Computer Based Education) which involves control, delivery, and evaluation of learning. It is used to prepare a database about the performance of a student and analysis is carried out on this basis. Marketing: Computers are used in marketing for advertising and selling more products. Healthcare: Computers have become an important part of hospitals, labs, and dispensaries, to keep the record of patients and medicines and to diagnose different diseases. Such as: Diagnostic System to collect data and identify the cause of illness. Patient Monitoring System to check the patient's signs for abnormality such as in Cardiac Arrest, Pharma Information System to check drug labels, expiry dates, harmful side effects, etc. Surgery is used in performing surgery. Engineering Design: Computers are widely used for engineering purposes. Such as: Structural Engineering for the design of ships, buildings, budgets, airplanes, etc. Industrial Engineering for design, implementation, and improvement of integrated systems of people, materials, and equipment. Architectural Engineering for planning towns, designing buildings, determining a range of buildings on a site using both 2D and 3D drawings. Military: The military employs computerized control systems in defences. Modern tanks, missile control, military communication, military operation and planning, and smart weapons are computerbased. Communication: Communication is a way to convey a message, an idea, a picture, or speech by the sender to the person for whom it is meant. A computer helps in transmitting the message via E-mail, Chatting, Usenet, FTP, Telnet teleconferencing (conference call) and Video- conferencing Government: Governments are the first computer users as they play an important role in government services. Such as budget planning, sales tax calculation, income tax department, track data for population, computerization of voters lists, and weather forecasting, police officers, dissemination of policies, etc. 12. COMPUTER COMMUNICATIONS When two or more PCs are connected using communication devices, messages can be sent and received. A stand-alone computer communicates very efficiently by connecting it with other computers. Data in a computer is transmitted to another computer located across continents almost instantaneously using a telephone, microwave, or radio links. The long-distance communication link between a computer and a remote terminal was set up around 1965. Now networking has become a very important part of computing activity. 32 Computer Network: A system consisting of connected nodes made to share data, hardware, and software is called a computer network. Networks are interconnected by copper wire, fibre optic cable, microwave, and infrared or through satellite. Some important reasons for networking are: to share resources, share information, and communicate. Intranet and Extranet Many organizations have a Local Area Network that allows their computers to share files, data, printers, and other resources. An intranet is a computer network within an organization that is accessed by the employees and others with authorization. All the Internet services such as web pages, email, chat; UseNet and FTP are provided on the intranet to serve the organization. The sensitive company data available on the intranet is protected from the outside world. The intranet connecting selected customers, suppliers, and offices in addition to the internal personnel, is called an extranet. By using extranet business organizations can save telephone charges. For example, a manufacturing company can extend its intranet to its dealers and customers for support and service. Applications of Network: The areas where computer networks are employed are; electronic data interchange, tele-conferencing, cellular telephone, cable television, financial services, marketing and sales, reservation of airlines, trains, theatres and buses, telemedicine, ATM, and Internet banking. Types of Networks: Depending on the geographical location, networks can be classified as 1. Local Area Network (LAN): a network confined to a single location like office, home, café, etc. 2. Metropolitan Area Network (MAN). a network that links more than one LAN. e.g. within a city. 3. Wide Area Network (WAN): a network that covers wide areas such as cities, states, countries, or continents e.g. Computers in different branches of a Globalised company, Internet, etc. Common Network Services: The following common network services are available, file services, print services, massage services, and application services Co-ordinating Data Communication: The device that coordinates the data transfer is called a Network interface card (NIC). NIC is fixed on the computer and the communication channel is connected to it. Ethernet, Arcnet, and token ring are the examples for the NIC. The protocol specifies the procedures for establishing maintaining and terminating data transfer. In 1978, the International Standards organization (OSI) provided a network architecture with seven layers, that helps to communicate between Network of dissimilar nodes and channels. Forms of Data Transmission: Data is transmitted in two forms: Analog data transmission which transmits data in a continuous waveform. While Digital data transmission is the widely used communication system in the world which is faster and more efficient than analog. 13. INTERNET, ONLINE RESOURCES, BROWSERS, AND SEARCH ENGINES 1) INTERNET 33 A network is a group of two or more computer systems linked together. The Internet is the largest computer network in the world, connecting millions of computers. The Internet is a global system of interconnected computer networks that carries a vast range of resources and services. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by networking technologies. Anyone connected to the Internet can reach, communicate, and access information from any other computer (host sites) connected to it. Unlike online services, which are centrally controlled, the Internet is decentralized by design. Each Internet computer, called a host, is independent. A Host a computer that allows websites to be located on the Internet. The description of a host's location on the Internet is called a domain name. Internet operators can choose which Internet services to use and which local services to make available to the global Internet community. Remarkably, this anarchy by design works exceedingly well. There are a variety of ways to access the Internet. Most online services offer access to some Internet services. It is also possible to gain access through a commercial Internet Service Provider (ISP) that provides new ways of accessing, interacting, and connecting with people and content. As a result, new terms are constantly appearing as new technologies are introduced. Who Governs the Internet? No one owns the Internet, and no single person or organization controls the Internet in its entirety. The Internet is more of a concept than an actual tangible entity, and it relies on a physical infrastructure that connects networks to other networks. However, there are voluntary organizations like Internet Corporation for Assigned Names and Numbers (ICANN) that promote global information exchange and administers the domain name registration to avoid a name that is already registered. Connecting a computer to the Internet: Before loading a web site, you first need to connect to the internet. Requirements for connecting to the Internet: a) Hardware: i) Modem: A modem is a communications device that allows a computer to connect and communicate with other computers through telephone lines. Modem stands for Modulator Demodulator. Once you have your computer, the primary hardware you need to connect to the internet is a modem. The type of internet access you choose will determine what type of modem you need. Dial-up access uses a telephone modem, DSL service uses a DSL modem, cable access uses a cable modem, and satellite service uses a satellite adapter. Your ISP may give you a modem (often for a fee) when you sign a contract with them, which helps to ensure that you have the right kind of modem. Fig. 13.1: a) A DSL modem b)A wireless rout ii) Router: A router is a hardware device that allows you to connect several computers and other devices to a single internet connection, which is known as a home network. Many routers 34 are wireless, that forward data between nodes on a wireless network. Many modems now include a built-in router. Most routers also act as a hardware firewall, which helps prevent people from gaining access to your computer through the internet. iii)A network card is a hardware that allows computers to communicate over a computer network. Modern computers have a network card built into the motherboard, so it, not something you will need to purchase. The network card will either have an Ethernet port, a wireless connection, or both. You can access the internet at any place that offers a Wi-Fi connection with any computer with a wireless connection. Fig. 13.2 Network Card iv. Computers b) Web Browser: A browser is a software program that is used to view web pages on the web. E.g. Internet Explorer, Netscape Navigator, Mozilla Firefox, Google Chrome, etc. c) Telephone line: A telephone line is required to transfer data from one computer to another. The computer is connected to a modem, which, in turn, is connected to a telephone line. such as ISDN, 56K leased lines, and T-1 connections d) Subscription with an Internet service provider (ISP): ISP ‘s are companies that provide access to the internet at different levels of speed based on your needs. We need a subscription with any ISP to get an Internet connection. If you are mainly using the internet for e-mail and social networking, a slower connection might be all you need, but if you want to download a lot of music or watch streaming movies, you'll want a faster connection. Some of the ISPs are AT&T WorldNet: Microsoft Network: America Online: In India: VSNL (Videsh Sanchar Nigam Limited, MTNL (Mahanagar Telecom Nigam Limited), BSNL (Bharat Sanchar Nigam Limited), Satyam Online, etc. e) Communication Software: Communication software is of two types: software that helps establish basic internet connectivity and software that helps to browse, access e-mail, etc. f) Protocols: These are set of formal rules describing how to transmit or exchange data across a network. The factors to consider, to connect to the Internet are how much speed (bandwidth) you need, where you live and internet service, wireless internet (Wi-Fi), home networking, or mobile phone internet access. Choosing an Internet Service Provider: You can determine which ISPs are available in your area that offer the type of internet access you want to purchase. Such as Talk to friends, family members, and neighbours to see what ISP they use. You have to consider the Speed, Price, Ease of Installation, Service Record, Technical Support, Contract Terms. When you register with an ISP the following are given: Username (a unique name that identifies you), Password-secret code that prevents other people from using your account, and E-mail address- A unique address that you can send or receive E-mails. 35 Access telephone number - Internet users can use this number to connect to the service provider. Fig.13.3b shows dialog boxes on the computer screen wherein the user name (Govt. Higher Secondary School, Chennai -600 003 abbreviated as a ghssch3), a password (alphanumeric of word length 8 characters appearing as ‘x’) and access telephone number are entered. By clicking on the dial button, the modem establishes a connection with the ISP Fig.13.3: Dialogue Box a and b for Connecting to the Internet There are two ways to look for information on the Web. If the URL of the website is known, enter it on the address bar (Fig.13.4). If the URL is not known, then ‘Search Engines’ will help us to get the information. Search Engines are tools that allow the user to find a specific document through keywords or menu choices. Some of the popular Search engines are Yahoo, Lycos, AltaVista, Hotbot, Google, and Askjeeves. Fig.13.4: Entering the URL Internet Explorer helps to use the net with the navigation buttons (Fig.6.12) on the toolbar Fig. 13.5: Navigation Buttons 1. Back button: This button helps to go back to the previous link. The small triangle adjacent to it displays a dropdown list of several recently used pages. Instead of pressing the back button several times, select a page from the list. 36  2. Forward button: This is similar to the back button. One can jump forward by one page or several pages. Popular uses of the web Research: The web provides research materials from libraries, research institutions, encyclopaedia, magazines, and newspapers. Some sample sites www.encarta.com the Internet Public Library site www.ipl.com and the Library of Congress www.loc.gov. Chatting: Some websites proved chat rooms to interact with an individual or a group. Free-wares: Some sites provide a free download of software, tutorials, and benchmarks. Education online: Educational institutions offer courses via the web. Students can attend and interact in a class from home using a computer. Online services: Online shopping, online booking for travel, and entertainment managing investments are the upcoming areas of the Internet that reach every home. Job searches: The digital revolution is changing everything it touches and the job market is no exception. Several web sites are assisting people in finding internships, jobs, and helps companies to fill job vacancies. There are sites relating to specific jobs and professions also. Some of these sites charge a fee for the services while others are free. 14. MAJOR FEATURES/ TERMINOLOGIES ON THE INTERNET: 1. The World Wide Web: It refers to the interconnection of sites all over the world that store information in multimedia form, accessible on the internet. The web is similar to a library, and it consists of billions of pages of hypertext documents (text, pictures, sounds, and animation) on various topics stored on different computers on the internet. Each page is called a web page. The WWW is a virtual network of web sites connected by hyperlinks (links). Web sites a series of interconnected servers on the internet also called a subset of the Internet. 2. Hypertext: is the text displayed on a computer with references (hyperlinks) to other text, tables, images, and other presentational devices, that the reader can immediately access, usually by a mouse click. 3. Hyperlinks: These are words or pictures that help to move from one page to another on the Web. They indicate the link to other sites. 4. Web Site: A group of related web pages linked together is known as a web site. The first page of the website is called a Home page. The Home page usually contains information about the site and links to other pages on that site. 5. Uniform Resource Locator(URL): is a unique address that specifies the exact location of the web page on the internet. An example of a URL is https:// www.country- watch.com/India where http – identifies the protocol necessary to retrieve file www – indicates that the site is on the world wide web country-watch - indicates the name (domain) of the web site.com – extension that identifies the domain type of the web site 37 /India – specifies the path of the file stored on the web server’s hard disk. 6. HTTP: The WWW support a protocol called HyperText Transfer Protocol (HTTP). This protocol is meant for transferring the web files over the text-based internet. The www portion of the address stands for “world wide web” and the next part country watch. com is the domain name. Generally, the domain name will be followed by a directory path, and the specific document address separated by slashes. Searching for information on the Internet is called surfing or browsing. To browse the Internet, a software called a web browser is used. 7. HyperText Mark-up Language(HTML): is the special language used to design a web page. HTML transmits a graphically designed web page with pictures, embedded sound, and animation. 8. File Transfer Protocol(FTP): is an Internet utility software used to uploaded and download files from one computer to another. It gives access to directories or folders on remote computers and allows software, data, and text files to be transferred between different kinds of computers. FTP works based on the same principle as that of Client/ Server. FTP “Client” is a program running on your computer that enables you to communicate with remote computers. The FTP client takes the FTP command and sends these as requests for information from the remote computer known as FTP servers. 9. A web browser: is software used for retrieving resources on the World Wide Web. The browser's main job is to access web sites and display web pages. It also lets you create Bookmarks (Favourites) for sites you like so that you can easily find them again later. Computer use to come with a browser preinstalled. A browser can exist without search engines. Examples of web browsers are Safari, Firefox, Google Chrome, or Opera, Internet Explorer and Netscape Navigator. 10. Search engines are specialized programs that help you find exactly what you're looking for on the Web. It provides a user interface were to enter one or more keywords, and the search engine will look for matching web sites from all over the Web and returns the results. A search engine needs a web browser to display its results. Some commonly used search engines are Google, Yahoo! MSN, Alta Vista, search, Infoseek, etc. A browser is programmed to browse webpages, while a search is to search and filter websites. 38  11. Web server: This is a program that responds to requests from web browsers to retrieve resources. Comparison of browsers and search engines Web Browser Search Engine Can exist without a search engine It needs a web browser Browse web pages and web sites Searches and filters websites Application locally installed Software system running on the Internet Source Google Chrome, Mozilla Firefox, Opera, Safari, Google, Yahoo, Bing, NATE, DuckDuckGo, etc. etc. 15. BROWSING THE WEB/INTERNET Reading information contained in the Web Pages on the Internet using browsers is called web browsing. To browse, enter the address of the website or address of any search engine in the address bar of the browser. If the address entered is a website, then the corresponding webpage will get displayed. If the address is of a search engine, then the webpage of the corresponding search engine will get displayed in Fig. 15.1. Fig. 15.1: Web browser home page In the ‘search tab’ enter the phrase you want to search tab. Then click the Search tab. A set of pages with the links to the webpages which contain information about your phrase in fig. 15.2 39 Fig. 15.2: A page with the links to other webpages Clicking any links desired will take you to those webpages.  To return to the last page you visited, click the Back button on the browser toolbar.  Click the Forward button to retrace your steps  To see one of the last nine pages you visited in this session, click the tiny black arrow to the right of the Back or Forward button, and then click the page you want from the list. To copy file from your computer to another computer a web page is called uploading. While to copying file from another computer on internet to your computer is called downloading. Downloaded files are accessed outside your browser. 16. APPLICATIONS OF INTERNET (ONLINE RESOURCES) Some of the important services provided by the Internet are: Electronic mail: E-mail is the most popular reason people use the Internet. Email is the fastest and one of the first means of communication for sending or receiving messages electronically on the Internet. With email, one can transmit text, data, software, and graphics as an attachment. There are several web sites on the internet that provide free email services. Such as Gmail, Hotmail, and yahoo. Discussion Groups: This is an email service that provides functions such as voting, and file uploading. Newsgroups are discussion groups that facilitate Internet users to discuss, debate, or share any topic as they are connected to the internet. FTP: File transfer service allows Internet users to access remote machines and retrieve software, games, photos, maps, music, and such other relevant materials. The process of receiving a file from the webserver to your computer is called downloading while sending files from your computer to a web server is called uploading. Telnet: Telnet is a special service that lets you use one computer to access the contents of another computer a telnet host. A telnet program creates a “Window” into the host so you can access files, issue commands, and exchange data. Telnet is widely used by libraries to allow visitors to look up information, find articles, and so on. Internet Relay Chat (IRC): IRC is a service that allows users to communicate in real-time by typing text in a special window. Like news, there are hundreds of IRC “channels” each devoted to a subject, user group, or chat room discussions using MSN, yahoo websites, etc. Video conferencing/teleconferencing: These are technologies that allow two or more locations to interact via 2-way video or audio transmission simultaneously. Today, there are many other ways to communicate online, including social networking, chat, VoIP, and blogging. Uses of Internet The internet is not just about finding information but it also helps to connect with friends, family, and people for personal and professional lives developments. The internet helps us achieve these in several different ways, including social networking, chat, VoIP, Intelligent Personal Assistants, and blogging. 40  1. E-commerce (Business & Commerce): On the Internet, services like internet banking, mobile banking, instant money transfer, online shops, online markets. Some many online stores and sites can be used to look for products as well as buy them using your credit card. You do not need to leave your house and can do all your shopping from the convenience of your home. It has got a real amazing and wide range of products from household needs, electronics to entertainment. 2. Entertainment: The Internet provides the facility to access a wide range of Audio/Video songs, plays films. Many of which can be downloaded. One such popular website is YouTube. 3. Software Downloads: You can freely download innumerable, software like utilities, games, music, videos, movies, etc. from the Internet 4. Blogs: You can create your blog and share your thoughts, knowledge, or interests that you’re passionate about with the world on the Internet. There are many sites like blogger.com and wordpress.com that let you create a blog for free. You don’t need any web design experience 5. Career and Employment: Students and graduates use social networks to network with professionals for internship and job opportunities. Even the professionals like doctors, access the internet to filter the necessary information for their use. 6. Education and educator support services: For online lecture delivery, certificate programmes, testing, virtual libraries, educational collaborations, etc. For the students and educational purposes, the internet is the largest encyclopedia widely used to gather information to do the research or add to the knowledge of various subjects. 7. News and broadcasting: For distribution of audio and video content to a dispersed audience via radio, television, or dig