computer application in management ch1234.pptx

This document include computer hardware, software and different parts of computer organization and overview different application of computer in management

1. Computer Application in Management v Arebu M. ODA BULTUM UNIVERSITY Prepared by 1

2. In this chapter you will specifically: Define clearly what is term computer . Explain History and generation of computer. Identify the characteristics of computer. Explain the application areas of computer. Identify the different type of computer . Main parts of computer 2

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4. A computer is an electronic device that accepts data, processes the accepted data, and then displays the result. More accurately, A computer is a machine which receive an input(data), processes it according to a predefined program/instruction and then stores it, and gives an output, i.e. provides the result in printed or visual form. The word ‘computer’ comes from the Latin word ‘ compute ’ means to calculate . Introduction to computers What is COMPUTER? 4

5. 1 ) Inputting: It is the process of entering raw data, instructions and information into the computer. It is performed with the help of input devices. 2) Storing: The computer has primary memory and secondary storage to store data and instructions. It stores the data before sending it to CPU for processing and also stores the processed data before displaying it as output. 3) Processing: It is the process of converting the raw data into useful information. This process is performed by the CPU of the computer. It takes the raw data from storage, processes it and then sends back the processed data to storage. The operations of computer components are given below 5

6. 4) Outputting : It is the process of presenting the processed data through output devices like monitor, printer and speakers. 5) Controlling : This operation is performed by the control unit that is part of CPU. The control unit ensures that all basic operations are executed in a right manner and sequence. Cont … 6

7. History of computers Computers was first invented to calculate huge mathematical tasks. A. The Abacus It is the earliest mechanical computational device. It was in use in the middle east as early as 2500B.C. Simple addition and subtraction can be carried out rapidly and efficiently by positioning the beads appropriately. 7

8. B. Pascal’s calculator It is the first true mechanical calculator . It was invented by a French mathematician called Blasé Pascal in 1642 and its known as Pascaline (Pascal's calculator) C. The difference engine Charles Babbage, a nineteenth century professor at Cambridge University, is considered to be the father of modern digital computers. The important contribution of Babbage’s engine was its ability to perform computations and print results automatically . History of computers 8

9. In 1842, Babbage comes out with his new idea of Analytical Engine that was intended to be completely automatic. History of computers 9

10. D. Herman Hollerith's tabulating machine Herman Hollerith is a statistician in 1880 and he develop his machine to speed up the process of census data. He develops his machine that uses the punched card. E. Mark I Developed by Howard A. at Harvard university (1944) which were the first electromechanical computer . History of computers 10

11. F. The ENIAC (Electronic Numerical Integrator and Calculator) It was the first general purpose digital computer. It is very huge occupying 15,000 square feet room and use 18000 vacuum tubes. The major drawback was it has to be programmed manually by setting switches and plugging & Unplugging cables. It doesn’t use internally stored memory. History of computers 11

12. G. The Von Neumann Machine Van Neumann forward the stored program. concept of the ENIAC project. i.e. It designing the computer to get its instruction by reading them from memory. H. Commercial Computers The 1950s century was the birth of computers industry with two companies , Spery and IBM , by demonstrating the market place. i.e. The development of successful commercial computer called UNIVACI ( Universal Automatic Computer History of computers 12

13. New Pen Computers History of computers 13

14. Continue… History of computers 14

15. Continue… History of computers 15

16. Generation of computers Generation in computer language is a steps in technology. We have five generation of computer The major characteristics that distinguish these generations of computer are the following. Types of electronic circuit element used Major secondary storage media used Computer language used. Types of operating system used Memory access time (time to store or retrieve a word of data from memory). 16

17. Generation of computers A. First Generation computers (1944-1955) used vacuum tubes as the principal electronic components. punched cards were the main sources of input and magnetic grams were used for internal storage. Memory access time was expressed in milliseconds. Very large in size, slow in performance and expensive in price. They uses machine & assembly language. Most application were scientific calculation . ENIAC & UNIVACI are examples of 1st generation computers. 17

18. Generation of computers B. Second Generation Computers (1955-1964) Transistor were the main ckt element. -Transistors are solid state device made from silicon. Magnetic tapes were used for main storage media. Memory access times were expressed in microseconds Emergence of high-level programming languages, like FORTRAN, COBOL, & ALGOL. (Easy to write) Batch operating systems is used that permit rapid processing of magnetic tape files. They are much faster than 1st generation computers. 18

19. Generation of computers C. Third Generation Computers (1964-1975) Transistors are replaced by Integrated circuits(IC) Magnetic disc storage became popular and provided direct access to very large data files. Access time in these computers was measured in nanoseconds (billionths of a second). Structured programming languages were introduced :PASCAL and BASIC. Creation of an independent software industry. 19

20. Generation of computers D. Fourth Generation Computers (1975-1989) ICs are replaced by Large Scale Integration (LSI) Access time in these computers was measured in nanoseconds (billionths of a second). Creation of MICROPROCESSOR. (for PCs). Spread of high-speed computer networking. (LAN & WAN) Several new operating systems were developed, like MS-DOS, Ms - Windows, and UNIX. Totally general purpose machines. 20

21. Generation of computers E. Fifth Generation computes (1989- Present) Totally general purpose machines. Very Large Scale Integration(VLSI) technology and also Ultra Large Scale Integration (ULSI) emerged . Larger main memory > = 256 Mb, and hard disk >= 80 GB are common Optical disks emerged named as CD-ROMs Distributed operating system for computer network. Portable notebook computers, powerful desktop PCs, and workstations, powerful servers and supercomputers 21

22. Generation of computers Fifth Generation computes (1989- Present) VLSI technology becomes Ultra Large Scale Integration (ULSI). Portable notebook computers, powerful desktop PCs, and workstations, powerful servers and supercomputers Larger main memory > = 256 Mb, and hard disk >= 80 GB are common Optical disks emerged named as CD-ROMs Distributed operating system for computer network. 22

23. Generation 1 st 2 nd 3 rd 4 th 5 th Circuit element Vacuum tube Transistor IC LSI VLSI SSD Punched card Magnetic Tape Magnetic disk Mass Device storage Language Machine & Assembly Fortran, COBOL Etc Structured language Application oriented Operating system Operator control Batch system Application oriented Time sharing Mem. Access time 1ms 10µs 10ns 1ns Approx. date 1946-57 1958-64 1965-71 From 1971 above Examples ENIAC, UNIVAC, UDVAC IBM7090, 7094 IBM system Late IBM Products 23 23

24. Characteristics of Computer 1. STORAGE Computes can handle large amount of data. Once recorded, The information can never be forgotten and can be retrieved with a fraction of a second. Its storage capacity is measured as follows: Bit = The smallest information stored in a computer(0 or 1). Byte = character = 8 bits. Kilobyte (KB) = 1024 bytes. Megabyte (MB) = 1024 Kilobytes. Gigabyte (GB) = 1024 Megabytes. Terabyte (TB) = 1024 Gigabytes 24

25. Characteristics of Computer 2 . SPEED Computers are very fast devices. They work at an incredible speed and perform millions of calculations and comparisons in a second. Its speed is measured by: Millisecond = 1/1000 of a second. Microsecond = 1/1000,000 of a second. Nanosecond = 1/1000,000,000 of a second. Pico second = 1/1000,000,000,000 of a second . 25

26. Characteristics of Computer 3. ACCURACY Computers process vast amount of data in a very high speed without committing errors Errors can occur mainly due to humans’ incorrect input data, and program instructions with a problem.(often called GIGO). 4. DILIGENCE Computers are not bored or become tired of performing many thousands of calculations repeatedly. 5. VERSATILITY A computer is capable of performing almost any task provided that the task can be reduced to a series of logical steps. For example, the same computer used for process payroll can also be used for Design computations or to track Inventory. 26

27. Characteristics of Computer 6 . DURABILITY and RELIABILITY Computers are durable and extremely reliable devices. They can operate error-free over long periods of time. 7. LACK of DECISION-MAKING Computers do not have the capacity to think by their own. Their IQ is zero and they had to be told what to do and in what sequence. 27

28. Types of Computers Their are different types of Computers. Their difference is depending on different categories of characteristics. Classification by the method of operation (processing) 1.Analog 2. Digital 3. Hybrid 1. Analog Computers Analog computers operate by measuring. They deal with continues variables; They are special purpose computers. They have limited accuracy. Examples: Thermometer Voltmeter Speedometer 28

29. Types of Computers 2. Digital Computers It deal with discrete variables. They operate by counting rather than measuring. Examples: • Abacus • Desk & pocket computers • The general purpose computers. Digital computers have higher accuracy and speed than the analog ones . 29

30. Types of Computers 3. Hybrid computers The best features of analog and digital computers can be combined into a single device to form a hybrid computer. Example: hospital insensitive (will convert the patient’s heart function, temp, etc in to number and supplied to digital comp,) Gasoline pomp (will convert the flow of pumped fuel) 30

31. Types of Computers Classification by purpose of application Classified into two(Special & General) 1. Special purpose computers They are designed to solve a single type of problem, Example: The public telephone box. Traffic control system . Ticket machines ( used in hotel, super market etc .) Pocket calculators etc. Most Analog computers are special purpose computers. 31

32. Types of Computers 2. General purpose computers They are designed to solve variety of problems through the use of “store program concept”. The same computer can be applied to solve another set of problem using different program. They are more flexible and versatile. Example: Micro computers Mini computers Super computers etc. 32

33. Types of Computers Classification based on their size, cost and power of execution • Supercomputers • Mainframe computers • Minicomputers • Microcomputers Supercomputers Supercomputers are the largest, most powerful, fast, extremely high storage and most expensive computers. computing speeds several times faster than mainframe computers primarily used for processing complex scientific applications. speeds measured in nanoseconds and even in picoseconds 33

34. Types of Computers Some application areas of super computers Weapons research (Military Industry) Large simulation in Aerospace & Automobile industry Oil exploration in the petroleum industry etc. 2. Main frame computers Mainframe computers are large computers frequently used in large organizations like banks, insurance companies, hospitals, airline reservation etc , Needs to process large number of transaction online and require computer system having massive data storage and processing power. 34

35. Types of Computers They are housed in a controlled and central location with several user terminal connected to them. The main difference between a mainframe and a super computer is that, a super computer channels all its power into executing a few programs as fast as possible, where as a mainframe uses its power to execute many programs concurrently. 35

36. Types of Computers 3. Minicomputers They are mainframe having smaller configuration (small hosts, less storage space and fewer user terminals) They are used in small companies. They can be accessed by more than one user at a time and are used in many application areas. They are smaller & less powerful than mainframe. They are large and more powerful than micro computers 36

37. Types of Computers 4. Microcomputers Also known as personal computers (pc). Use Microprocessors inside it. Generally designed to be used by one person at a time. ( Single user ). They have limited input and output capacities and little storage capacity. A microcomputer with a powerful microprocessor & a high quality monitor is called a workstation. 37

38. Types of Computers Two physical models of PCs are: Desktop model Tower model Other portable PCs are:- Laptop, Notebook, palmtop etc. 38

39. Why we use Computers? Store and process large amount of information with high speed and accuracy. Transmit information across continents through communication medias. Perform complex mathematical computations and make comparisons. Simulate events; Monitor ongoing industrial operations; Perform repetitive processes great ease, speed, and reliability. 39

40. The main areas of computer applications IN OFFICES: - Type writers are being replaced by computers. IN EDUCATION: - Computers are widely used in educational fields; for instruction and administration / Interactive education / CAL -Computer Aided Learning CAI- Computer Assisted Instruction IN LBRARIES 40

41. IN COMMUNICATION:- Computers can be used in different ways for communication purpose between users. This can include: - Fax- hard copy - Electronic mail -Internet IN RESEARCH IN BUSINESS IN MANUFACTURING Computers can be used in production process, from the design stage to the manufacturing stage. CAD - Computer Aided Design CAM - Computer Aided Manufacturing 41

42. IN MEDICINE E.g. telemedicine Application of Computers 42

43. Overview of a Keyboard Is an input device that goes into your computer which allows you enter information such letters from the alphabets, numerical data, symbols, and commands There are many keyboards, although not all have the same layout style. most common kind is referred to as a QWERT keyboard, which is named after the keys on the top rows of letters The keyboard is divided into several groups based on the function. Main Parts of a Computer 43

44. Cont … 44

45. The functions keys, labeled from F1 to F12, are used to perform specific tasks based on the operating system and software used For an example, in many programs, the key F1 is commonly used as the Help file In some cases, it can control the monitor brightness or the sound volume. The functionality of these keys differentiates from program to program and operating system to operating system Function Keys 45

46. Special Keys 46 The special keys are used alone or in combination with other keys to perform certain actions These include the Control (ctrl), Alternate (Alt), Escape (Esc), Windows, Tab, Caps Lock, and Shift keys . For an example, in many programs pressing “ Ctrl+S ” will save a file automatically

47. The Shift key is a combination key used with another letter to type an uppercase letter The Caps Lock key allows all letters to be typed in uppercase without having to press shift. This function can be turned on or off. An indicator light might be present to show that the function is on Most keyboards include a special key called the Windows logo key. This key is used to open the Start menu, or is used in combination with a second key to perform common Windows tasks Cont … 47

48. Navigation Keys They are used for moving around in documents or webpages and editing text. Navigation keys include Delete, Insert, Home and End, and Page Up and Page Down keys The Home key is used to move the cursor to the beginning of a line or to move to the top of the webpage The Left , Right, Up, and Down Arrow keys is used to move the cursor or selection one space or line in the direction of the arrow, or scroll a webpage in the direction of the arrow. Cont … 48

49. The PrtScn is used to capture an image of your entire screen known as a screen shot which copies into your computer’s clipboard. Cont … 49

50. What is Mouse ? A mouse is a small hardware input device used by hand. It controls the movement of the cursor on the computer screen and allows users to move and select folders, text, files, and icons on a computer. It is an object, which needs to put on a hard-flat surface to use. Is an input device that goes into your computer which allows you can to move, select, and open items on your computer screen. Overview of Mouse Device 50

51. A mouse is capable of performing various functions on a computer, which are as follows: Move the mouse pointer: Select: Open or execute a program: Drag-and-drop:. Hovering: Scroll Up & Down: Playing Game: What are the uses of a Mouse ? 51

52. There are different types of mouse used with a computer. In modern times, an optical mouse is one of the most common types of the mouse for a desktop computer that connects to the USB port, which is called a USB mouse. And the touchpad is the most popular type of mouse used for laptop computers. Types of Mouses 52

53. A list is given below with several types of the mouse: Optical Joystick Mechanical Cordless (Wireless) Foot mouse Touchpad (Glide point) Trackball TrackPoint J-Mouse IntelliMouse (Wheel mouse) Laser Mouse Cont … 53

54. A monitor is a display device like a TV screen that interprets and displays the graphical output signal from your computer’s graphics card and displays it on the screen. There are 9 different types of monitors, which are given below. LCD Monitor LED Monitor Curved Monitor CRT Monitor Flat Panel Monitors Touch Screen Monitors OLED Monitors DLP Monitors TFT Monitor Overview of a Monitor (Screen ) 54

55. Monitor is an output device which display items on the desktop/screen, this one is a CRT (Cathode Ray Tube) 55

56. All computers have a motherboard that is a circuit board to connect all of the various parts of a computer together. Its main purpose is to hold the CPU and the connections between the CPU and all the other subsystems. The RAM of the computer is found on the motherboard. Most motherboards have places were other types of devices such as graphics accelerator cards and network cards, can be inserted to extend or enhance the capabilities of the computer. Overview of Computer case (system unit) 56

57. The system unit houses an array of storage and file transfer devices, located in the front panel for easy access A computer’s system unit typically contains circuit boards, a power supply, and storage devices A few wires and cables connect storage devices to the power supply and circuit boards Ports and sockets to connect to input and output devices(Called peripheral devices) Fans to cool the components and indicator lights Cont … 57

58. Internal of system unit 58

59. A computer, works by changing information into binary numbers (ones and zeros) and then using simple to make decisions about how to rearrange those numbers into words or actions. A digital system stores and operates on information in a very specific way by storing information in a bit (or multiple collections of bits). A bit is a variable that can have only one of two values: it can either be a 1, or be a 0. HOW COMPUTERS WORKS 59

60. Computer’s functions are based on the movement and transformation of electrical pulses (representing ones and zeroes) in electrical circuits. Inside the computer are electrical circuits that decode the zeros and ones, by adding and subtracting them. These circuits are called the logic of the computer, because the calculations they make are similar to simple logic decisions. For example, if you press the A key on the computer keyboard, circuits inside the computer receive pulses of electricity representing the A in binary form - 1000001. Those pulses are sent to logic circuits that make yes or no decisions based on the input they receive. A very simple example would be a circuit that determines whether the input send to it is a one or a zero. The output of the circuit is a new piece of information - a binary one or zero that is the result of the simple yes or no decision. Cont … 60

61. Data Representation Method in computer A word in the memory of computer can represent character data or numeric data. When we say character data they are letters and digits (A-Z or a-z or 0-9), special symbols such as ?,*,+ … and control characters which used to control devices. But since computers is an electronic device which understands electrical signal there is no letter, symbol or number inside the computer. The most elementary form to organize data in an electronic device is in the form of a code which utilizes the “ON” & “OFF” states of electric switches. (current & no current states) 61

62. Data Representation Method An electronic devices has similarity with the binary number system in that both represent only two elementary states. Therefore binary number system is a convenient way to represent data in a computer system. An “ON” corresponds to a 1 and “OFF” corresponds to a . In the computer “ON” is represented by the existence of a current and “OFF” is represented by non existence of current. On a magnetic disk, the same information is stored by changing the polarity on the disk’s surface. of magnetized particles 62

63. Data Representation Method Data are represent in the form of a code that can have a corresponding electrical signal. Coding Methods It is possible to represent any of the character in our language in a way that a series of electronic switches in arranged manner. This switch arrangements can therefore be coded as a series of equivalent arrangements of 0’s & 1’s (bits). There are different coding systems that convert one or more character sets in to computer codes. Some of them are: 1 . EBCDIC, 2 . BCD 3. ASCII-7 & ASCII-8. 63

64. Data Representation Method In each case the character set group in to zones & digits. Zones:- group characters together to make the data process easier. Digit Code:- used to identify the individual character with in each zone. BCD (Binary Coded Decimal) BCD is one of the early memory codes. There are two types of BCD coding techniques. BCD (4 bits) BCD (6 bits) 64

65. Data Representation Method BCD (4 bits) It is based on the idea of converting each digit of a decimal number into its binary equivalent rather than converting the entire decimal value in to equivalent binary form. Example:- To represent 2l9 using 4 bit BCD 219 10 = 0010 0001 1001 in BCD Decimal Digits BCD Equivalent 0000 1 0001 2 0010 3 0011 4 0100 5 0101 6 0110 7 0111 8 1000 9 1001 65

66. Data Representation Method But 4 bits can only represent 2 4 (16 characters) and also the 4 bits BCD uses only 10 of them. (from 0000-1001) Because 4 bits are insufficient to represent various characters, the 4 bits BCD are used to represent only decimal numbers. BCD (6 bits) It uses 6-bits to code a Character (2 for zone bit and 4 for digit bit) It can represent 2 6 = 64 characters (10 digits, 26 capital characters and some other special characters). 66

67. Data Representation Method BCD Coding Sample E.g. EBCDIC Pronounced as “ Eb -See-Dick” and stands for Extended binary Coded Decimal Interchange Code. Mostly used by IBM Mainframe model and in similar machines produced by other manufacturers. It is an 8-bits coding scheme (4 bits for zone and 4 bits for digit). character BCD code Zone Digit A-I 3 1-9 J-R 2 1-9 S-Z 1 2-9 0-9 0-9 character BCD code Zone Digit F 11 0110 L 10 0011 T 01 0011 8 00 1000 67

68. Data Representation Method It accommodates to code 2 8 or 256 different characters (00000000 – 11111111). It is a standard coding scheme for the large computers. EBCDIC Coding Sample E.g. character EBCDIC code Zone Digit A-I 12 1-9 J-R 13 1-9 S-Z 14 2-9 a-i 8 1-9 j-r 9 1-9 s-z 10 2-9 0-9 15 0-9 character EBCDIC code Zone Digit B 1100 0010 M 1101 0100 Z 1110 1001 b 1000 0010 j 1001 0001 y 1010 1000 4 1111 0100 68

69. Data Representation Method ASCII-7 ASCII stands for American Standard Code for Information Interchange. Widely used before launching of ASCII-8. Uses 7 bits to represent a character (3 bits for zone bit and 4 bits for digit) . With the seven bits, 2 7 ( or 128) different characters can be coded (0000000-1111111). ASCII-7 Coding Sample E.g. character ASCII code Zone Digit 0-9 3 0-9 A-O 4 1-15 P-Z 5 1-10 character ASCII code Zone Digit 011 0000 L 100 1100 T 101 0100 69

70. Data Representation Method ASCII-8 Also referred as Extended ASCII. Is the most widely used type of coding scheme for Micro Computer system. Uses 8-bits to represent alphanumeric characters (4 bits for zone and 4 bits for digit). With the eight bits, 2 8 ( or 256) different characters can be coded (00000000-11111111). ASCII-8 Coding Sample E.g. character ASCII-8 code Zone Digit 0-9 3 0-9 A-O 4 1-15 P-Z 5 1-10 a-o 6 1-15 p-z 7 1-10 character ASCII-8 code Zone Digit 0011 0000 L 0100 1100 T 0101 0100 a 0110 0001 y 0111 1000 70

71. Units of Data Representation Their is a Unit for the data to store, process or communicate with in the computer system. The units from the smallest to the largest are called bit, byte and word. This units are based on the binary number system. Bit Bit stands for binary digits . Bits are the smallest units and can convey only two possible states 0 or 1. A bit is a single element in the computer, on a disk that stands for either “ON” indicating 1 or “OFF” indicating 0. 71

72. Unit of Data Representation In the computer “ON” is represented by the existence of current and “OFF” is represented by the non-existence of current. On a magnetic disk , the same information is stored by changing the polarity or magnetized particles on the disk’s surface. Byte It is a group of bits used to represent a symbol. It is the “ basic unit of data representation ” in the computer system. The term byte is commonly used to mean an 8 bit byte. 72

73. Unit of Data Representation Since each bit has two states and there are 8 bits in a byte , the total amount of data that can be represented is 2 8 or 256 possible combinations. Each byte can represent a character. (a character is either a letter, a number or a special symbol such as +,-,?,*,blank space, $, etc.) A byte is then used as a unit of measurement in the computer memory, processing unit, external storage and during communication. 73

74. Unit of Data Representation If the computer memory is 524288 byte , this is expressed in short by saying 512KB , where KB stands for kilobyte. 1 Kilobyte (1KB) is 2 10 or 1024 bytes. 1 Megabyte (MB) is 2 20 bytes or 2 10 kilobytes. 1 Gigabyte (GB) is 2 30 bytes or 2 20 kilobytes. Word A combination of bytes , then form a “word”. Word refers the number of bits that a computer process at a time or a transmission media transmits at a time . 74

75. Unit of Data Representation Although bytes can store or transmit information, the process can even be faster if more than one byte is processed at a once; A word can contain one, two, three or four bytes based on the capacity of the computer. Word length is usually given in bits. We say that a computer is an 8-bits, a 16 bit, a 32 bit or a 64 bit computer to indicate that the amount of data it can process at a time. When the word length is larger a computer will became more powerful and faster. 75

76. CHAPTER TWO 76

77. Components of a Computer System A computer system composed of Computer hardware and Computer software. Computer Hardware The physical components which we can touch and see. We can further classify the hardware as follows: Input devices Central Processing Unit (CPU) Memory Unit (Primary memory/Main memory) Secondary storage devices Output devices. Storage unit 77

78. Components of a Computer System 1. Input Devices Input is the process of giving or inserting data and instructions to the computer system. Functions of input devices are: It accepts (read) instructions and data from the outside world It converts these instructions and data into computer acceptable form. Examples of input devices:- • Keyboard • Mouse • Scanner • Light pen • Microphone • Bar code reader • Voice synthesizer • Touch Screen etc. 78

79. Components of a Computer System Basic organization of a computer system 79

80. Components of a Computer System 2.The Central Processing Unit (CPU) It is the main component of a computer. Consists of the Control Unit, Arithmetic Logic Unit Very costly. Purpose of CPU Fetch instruction from memory. Interpret instruction. Fetch data from memory or input units. Process data. Write data to the user or output devices. 80

81. Components of a Computer System The Control Unit Performs all the control functions of the computer. Fetches the instruction from memory. Determines the next instruction to be executed by the computer. Serves as the computer traffic cope . The Arithmetic Logical Unit (ALU) Referred as the computers " number crunchier ". Performs the arithmetic operations (addition, subtraction, multiplication and division) Registers: are temporary storage locations for managing instructions and data as they are being processed in control & ALU. 81

82. Components of a Computer System Memory Unit (Primary Memory) Directly accessible by the control unit and ALU. The main memory has two parts . RAM (Random Access Memory) ROM (Read only Memory) RAM is:- Small in storage capacity - Fast in processing speed - Volatile - Expensive in price. ROM is:- non-volatile - permanent data storage 82

83. Components of a Computer System Secondary storages: Are non-volatile, they store data and information permanently, Are cheap or low in cost, Operating speed far slower than the primary storage. Store large amount of information. Example : Types of magnetic disks Floppy disk Hard disk Types of optical disks CD-R CD-RW DVD R/RW 83

84. Components of a Computer System Output Devices Output is computer produced text, graphics, or sound in hard-copy or soft-copy format that can be used by people. Output device- is an electromechanical device that accepts data from a computer and translates them into a form suitable for use by the user. Examples of output device are: -Printers -Monitors (screens) -Speakers -Plotters , etc 84

85. Components of a Computer System BUS:- is an electrical pathway through which bits are transmitted between the various computer components. There are three buses inside the computer Address Bus: is a unidirectional bus over which digital information is transferred to identify either a particular memory location or particular I/O address. Data Bus: a bus system which interconnects the CPU, memory and all the peripheral Input/output devices of a computer system for the purpose of exchanging data. Control Bus: a bus used to select and enable an area of main storage and transmit signals required to regulate the computer operation. 85

86. Computer Software Components Software is a set of instruction or programs that order the hardware what to do or to do something Program is a finite set of instructions (steps) that the computer follow to perform a given job. Software: - Is a collection of programs. Software also includes documentations, rules and operational procedures. It is an essential component of the computer system. Without the software , the computer hardware cannot solve our problems. Software acts as intermediate b/n the user and the electronic components of the computer . USER Software Hardware 86

87. Computer Software Components Computer software is classified into two major class 1. System software 2. Application software 1. System software Are programs which facilitate the work of the computer hardware. It organizes and manages the machine’s resources, handles the input/output devices. It controls the hardware by performing functions that users shouldn’t have to or are unable to handle System programs make complex hardware more user friendly. It enables the computer to understand programming languages i.e. it serves as means of communication between user and a computer. 87

88. Computer Software Components The important categories of system software are: A) Operating system B) Language software A) Operating system Operating system coordinates the activity between the user and the computer. It also provides an interface between a user and an application program and the hardware. Directing all processing activities within computer, calling in other systems software when needed, scheduling jobs, allocating storage facilities, activating input and output devices, etc. are some of the importance of operating systems software. 88

89. Computer Software Components An operating system has three major functions. i . Controlling operations (control program) ii. Input/output Management iii. Command Processing (command Interpreter) i . Controlling operations (control program) Coordinates , or supervises the activity of the computer system. Decides where programs and data should be stored in the computer memory. Handles communications among the computer components, applications software and the user. Controls the saving and retrieving of files to and from disks in the disk drive. It performs all its controlling tasks with out the involvement or awareness of the user. 89

90. Computer Software Components ii. Input/output Management The I/O manager coordinates, The computers communication with outside world , The flow of data to the display screen and other output devices (printers/ plotters) and The flow of data from the key board or other input devices. Handles the flow of data to and from the disk drives (file management). Handles the process of preparing a disk for use, the copying, renaming, erasing task of a file . 90

91. Computer Software Components iii. Command Processing (command Interpreter) It interprets the commands or what you enter using the keyboard or other input devices. If you write an internal command it carries out the function of that command if it is external command or other executable file it searches for the corresponding file in the default (current disk) or the user specified disk, loads the file into memory and transfers control to that program. Once this program is terminated, control returns to command and the program for that command or file is discarded from memory. 91

92. Computer Software Components Types of Operating Systems Operating systems can be classified by: The number of programs they can handle at a time and The number of users they serve at once at one or different stations ( i.e. terminals or micro-computers connected to a central computer ). i . Single tasking operating systems. ii. Multi user operating system. iii. Real Time Operating System. 92

93. Computer Software Components i . Single tasking operating systems With single tasking operating systems only one program can be run on a computer at a time. ii. Multi user operating system It supports a number of work stations connected to a central system. A number of users can use the resources of one high capacity computer by the help of terminals. iii. Real Time Operating System A real time is a system that is capable of processing data so quickly that the results are available to influence the activity currently taking place. 93

94. Computer Software Components B) Language Software. Are systems software that serves to write set of instructions or programs that are required to solve a problem. Are software which are used by programmers to develop application software and translate programs to machine code. They provide a set of rules, symbols, and special words to construct a program. They serve as editors and translators to develop programs in a number of programming languages. Includes:- translators, general purpose routines & utilities and high level languages 94

95. Computer Software Components Translator:- is a program that converts one or more languages to another language.(3 types) Assemblers:- is a program that translates assembly languages into machine code. Compiler:- is a program that translates a high level language into machine code.(Pascal, Fortran, Cobol) Interpreter:- is a program that translates each instruction of high level language & executes the instruction before translating the next instruction. The general-purpose routine and utilities include programs which are used to handle file processing, editing and debugging. High level language software is a software which has its own compilers to detect syntax errors of the user’s program code.(E.g. COBOL, Fortran etc ) 95

96. Computer Software Components Application Software Is a software that is designed to perform tasks for the specific areas. Type of application software 1.Word Processors/ Word processing It is a computerized typewriter which permits the electronic creation, editing, formatting, filing and printing text. Example:- WordStar, WordPerfect, Microsoft word 2.Spreadsheet ( is an electronic worksheet ) Using the programs built-in function you can perform complicated calculations complex mathematical problem. E.g. Lotus 1-2-3,MicrosoftExcel,Quatropro 96

97. Computer Software Components 3. Database management system. Allow you to store information on a computer, retrieve it when you need it and update it when necessary. Example: Microsoft Access, Oracle, SQL Server Dbase IV, FoxPro, etc. 4. Computer Graphics Computer graphics is the technique of creating, editing, displaying and printing graphs, diagrams, charts and images in a computer system. Graphics can communicate information that would be difficult or even impossible to put into words. Popular e.g. Lotus Freelance, Harvard Graphics, Print master, etc 97

98. System Software Application Software The main purpose of this software is to manage the resources available in the system. It serves as an effective forum for the execution of application software Application software designed to achieve a certain set of tasks. System software is documented in a low-level programming language like machine code or assembly language. Application software is composed in a high-level language like  Java ,  C++ , .Net , or  PHP. Usually, when the computer is switched on, system software begins to run and stops when the computer is switched off. When a user requests, application software runs according to the task it is assigned. Without system software, a computer system cannot even activate. User-specific application software is definitely not required to run the system. System software comprises language processors (interpreters, compilers, and assemblers), operating systems, and so on. Payroll software, accounting software, MS Office, and so on are perfect examples of an application software. 98 Difference Between System Software and Application Software

99. Chapter 4 Introduction to computer security 99

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101. Computer Information and Data Security It is important to avoid data and information loss in case of hard disk crashes. The only solution is to regularly keep backups of all the data on other media such as magnetic tapes, CD-ROM, etc. It is a good practice to store the media off-site and in case of a disk crash, restore the information from the backup media onto the new disk. 101

102. Computer Information and Data Security In case a backup media is not affordable, one should try and store the files on at least two different media devices. These media devices should be systematically kept at a place which is safe and secured, as the information contained may be confidential. People usually backup database files, spreadsheet files and large documents. As the technical constraints are always there, it is better to take regular backups, in order to avoid any loss of information. 102

103. Computer security is a technical developed to protect single computers and Network- Lined computer system from accidental or intentional harm including destruction of computer hue & sue. One of the causes of disaster on a computer system is computer virus. There are different types of security methods. Some of which are as follows:- 1)Disaster Recovery Plans : It is Periodical testing and upgrading of the contents of the computer. It helps to safe guard documents from sudden damage. 2)Application Safeguards : Protecting the computer itself and the document within the system from internal and external damage. 103

104. 3) Intrusion Selection Systems : it Security software called intrusion detection systems may be used in computers to detect unusual and suspicious activity and, in some cases, stop a variety of harmful actions by authorized or unauthorized persons. Abuse and misuse of sensitive system and application programs and data such as password, inventory, financial, engineering, and personnel files can be detected by these systems 4)Firewalls : Software placed between the networked computers and protects the networked computers. The firewall examines, filters, and reports on all information passing through the network to ensure its appropriateness. 5)Passwords 6)Backup 7)Encryption 104

105. Computer system security threats A computer system can be exposed to risk of security threats. These security threats can be of different types. The following are the major threats which can disrupt security in a computer system. Trojan Horse Viruses Worms Trojan Ho 105

106. Computer Virus It is a computer program that can copy itself and infect a computer without permission or knowledge of the user. They are deliberately created by programmers , or by people who use virus creation software. A virus can only spread from one computer to another when:- A user sends it over the network, A user carry it on a removable medium such as a floppy disk, CD, or USB drive. viruses can spread to other computers by infecting files on a network file system. 106

107. Boot Sector Virus – It is a type of virus that infects the boot sector of floppy disks or the Master Boot Record (MBR) of hard disks. The Boot sector comprises all the files which are required to start the Operating system of the computer. The virus either overwrites the existing program or copies itself to another part of the disk. Direct Action Virus – When a virus attaches itself directly to a .exe or .com file and enters the device while its execution is called a Direct Action Virus. If it gets installed in the memory, it keeps itself hidden. It is also known as Non-Resident Virus. Resident Virus – A virus which saves itself in the memory of the computer and then infects other files and programs when its originating program is no longer working. This virus can easily infect other files because it is hidden in the memory and is hard to be removed from the system . Types of Computer Virus 107

108. Multipartite Virus – A virus which can attack both, the boot sector and the executable files of an already infected computer is called a multipartite virus. If a multipartite virus attacks your system, you are at risk of cyber threat. Overwrite Virus – One of the most harmful viruses, the overwrite virus can completely remove the existing program and replace it with the malicious code by overwriting it. Gradually it can completely replace the host’s programming code with the harmful code. Polymorphic Virus – Spread through spam and infected websites, the polymorphic virus are file infectors which are complex and are tough to detect. They create a modified or morphed version of the existing program and infect the system and retain the original code. File Infector Virus – As the name suggests, it first infects a single file and then later spreads itself to other executable files and programs. The main source of this virus are games and word processors. 108

109. Computer Security Practices Virus prevention Purchase an anti virus program that runs as you boot or work your computer and update it frequently . Execute only programs of which you are familiar as to their origin. Load only software from original disks or CD’s. Pirated or Copied software is always a risk for a virus. Programs sent by email should always be suspicious. 109

110. Virus removal One possibility on Windows XP is a tool known as System Restore, which restores the registry and critical system files to a previous checkpoint. There are so many anti-virus software in the computer market that we can use to remove virus from an infected file. MacAfee, Dr. Solomon, Norton etc Operating system re-installation. 110

111. Backup In information technology , a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. These additional copies are typically called "backups." The verb is back up in two words, whereas the noun is backup (often used like an adjective in compound nouns). Backups are useful primarily for two purposes. The first is to restore a state following a disaster (called disaster recovery ). The second is to restore small numbers of files after they have been accidentally deleted or corrupted. Data loss is also very common. 66% of internet users have suffered from serious data loss. 111

112. Backup In information technology , a backup or the process of backing up refers to making copies of data so that these additional copies may be used to restore the original after a data loss event. These additional copies are typically called "backups." The verb is back up in two words, whereas the noun is backup (often used like an adjective in compound nouns). Backups are useful primarily for two purposes. The first is to restore a state following a disaster (called disaster recovery ). The second is to restore small numbers of files after they have been accidentally deleted or corrupted. Data loss is also very common. 66% of internet users have suffered from serious data loss. 112

113. Encryption a process of converting messages or data into a form that cannot be read without decrypting or deciphering it. The root of the word encryption—crypt—comes from the Greek word kryptos, meaning “hidden” or “secret .” 113

114. Thank you ! 114