Software brings the machine to life When a

Software brings the machine to life • When a computer is using a particular program, it is said to be running or executing that program. • Two major categories of software: • System software, i. e. , operating system • Application software 1

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Software: Operating Systems • The operating system tells the computer how to interact with the user and how to use devices such as the disk drives, keyboard, and monitor. The operating system is continue to run until the computer is turned off. • When a computer is turned on, it goes through steps to prepare itself to run user's application: 1. Self-test. Identify the attached devices, the amount of memory available and their functioning. This routine is initiated by a part of system software located in read-only memory(ROM). 2. Next, the computer runs the operating system program stored in diskette or hard disk. 3. After the computer finds and runs the operating system, the user can issue commands to the computer. 3

Software: Application Software • Application software is a program that help people accomplish specific tasks. • Thousands of application are available; however some major categories that likely to be encounter are: • Word processing software • Spreadsheets • Database management software (DBMS) • Multimedia, graphic and presentations • Utilities • Communication 4

Word processing 5

Spreadsheets 6

Graphic 7

Presentations 8

Data Objectives • The difference between data and information • Two reasons why computers use the binary number • Two main parts of CPU and how they work • Three differences between RAM and ROM • Three hardware features that affect processing speed • Two best-known families of CPUs and there differences 9

In this chapter: • Transforming data into information • Number bases • Bits and bytes • Text codes • How a computer processes data • Factors affecting processing speed • CPUs used in personal computers • Extending the processor's power to other devices 10

Transforming Data Into Information • Computers cannot understand anything about us. All they can do is recognizing two distinct states produced by electricity, magnetic polarity, or reflected light. All they can understand is whether a switch is on or off. • The CPU consists of several million tiny electronic switches called transistors. A computer assembling its individual on/off switches into patterns that are meaningful to us. • In strictest sense, data consists of the raw numbers that computers organize to produce information. • Computers turn raw, separated data into meaningful information. 11

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How Computer Represents Data • To a computer, everything is a number. • For computer, the sentence “Here are some words. ” is represented by: 13

Number Bases • A number base is a specific collection of symbols on which a number system can be built. • The number base familiar to us is base 10, upon which the decimal number system is built. There are ten symbols, 0 through 9, used in decimal system. When we need to represent a number greater than 9 we use two symbols together; as 9 + 1 = 10. Each symbol in a number is called a digit, so 10 is a two-digits number. • Other number systems: - The Binary Number System: Base 2 The Octal Number System: Base 8 The Hexadecimal Number System: Base 16 14

Number Base Systems Decimal(10) Binary(2) Hexadecimal (16) Octal(8) 0 0 1 1 2 10 2 2 3 11 3 3 4 100 4 4 5 101 5 5 6 110 6 6 7 111 7 7 8 1000 10 8 9 1001 11 9 10 1010 12 A 11 1011 13 B 12 1100 14 C 13 1101 15 D 14 1110 16 E 15 1111 17 F 16 10000 20 10 17 10001 21 11 18 10010 22 12 19 10011 23 13 20 10100 24 14 15

Numbers in a computer • In a computer, all data must be reduced to electrical switches. A switch has only two states --”ON” or “OFF” -- so it has only two numeric symbols. 0 stands for “OFF”, and 1 stands for “ON”. • Computers function in a binary number system (base 2). • When a computer needs to represent a quantity greater than 1, it uses the second digit. 16

Bits and Bytes • When referring to computerized data, each switch--whether on or off-- is called bit. The term bit is a contraction of binary digit. A bit is the smallest possible unit of data. • To represent anything meaning--that is to convey information-the computer needs groups of bits. The larger unit of data is the byte, which is a group of 8 bits. With one byte, the computer can represent up to 256 different values because it is possible to count from 0 to 255 with 8 binary digits (one byte). One byte combination is an enough unit to represent all the characters on the keyboard, including all letters (uppercase and lowercase), numbers, punctuation marks, and other symbols. (ENGLISH) 17

Text Codes The programmers need a standard code which is group of numbers to represent or stand for letters of the alphabet, punctuation marks, and other symbols. ASCII Unicode 18

ASCII The American National Standard Institute (ANSI) solution to represent the symbols with bits of data was the ASCII character set. ASCII = American Standard Code for Information Interchange Today ASCII is the most common character set used. ASCII is the seven bits code and can specify characters up to 127. The ISO (International Standard Organization) standard expanded on the ASCII character set, to offer different sets of characters for different language group. 19

Dec Hex Code 32 20 space 64 40 @ 96 60 ` 33 21 ! 65 41 A 97 61 a 34 22 " 66 42 B 98 62 b 35 23 # 67 43 C 99 63 c 36 24 & 68 44 D 100 64 d 37 25 % 69 45 E 101 65 e 38 26 $ 70 46 F 102 66 f 39 27 ‘ 71 47 G 103 67 g 40 28 ) 72 48 H 104 68 h 41 29 ( 73 49 I 105 69 i 42 2 A * 74 4 A J 106 6 A j 43 2 B + 75 4 B K 107 6 B k 44 2 C , 76 4 C L 108 6 C l 45 2 D - 77 4 D M 109 6 D m 46 2 E . 78 4 E N 110 6 E n 47 2 F / 79 4 F O 111 6 F o 48 30 0 80 50 P 112 70 p 49 31 1 81 51 Q 113 71 q 50 32 2 82 52 R 114 72 r 51 33 3 83 53 S 115 73 s 52 34 4 84 54 T 116 74 t 53 35 5 85 55 U 117 75 u 54 36 6 86 56 V 118 76 v 55 37 7 87 57 W 119 77 w 56 38 8 88 58 X 140 78 x 57 39 9 89 59 Y 121 79 y 58 3 A : 90 5 A Z 122 7 A z 20

UNICODE Unicode Worldwide Character Standard represents each symbol by two bytes --16 bits. With two bytes, a Unicode character can be any one of more than 65, 536 different characters or symbols. Many software publishers, including Microsoft, Netscape, and Accent, encourage their developers to use Unicode in their programs. 21

User • Job related to computer – Computer Engineer – System Administrator – Network Administrator – System Analysis – Programmer – Tester – System Maintenance 22

User • Job related to computer Many jobs use computer as a tool. – Accounting – Draft man – Animator – Data entry – Customer support 23

User • Responsibility of the user – Keep computer from virus – Recognize limit of computer – Use computer for work 24

User • • Virus, Worm, Trojan, e-mail fraud Virus protection program Updating software, patch Spy ware removing program 25

User • Hardware error – CPU design error – Hardware failure – backup • OS failure • Application software error • Appling wrong way 26

User • Web site content – censorship • E-mail , icq -- work monitoring 27

การสงผานขอมล Simplex Half duplex Full duplex 35

สายสงสญญาณ Wire pairs Microwave Coaxial Cables Satellite Fiber Optics 39

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เครอขายไคลเอน /เซรฟเวอร (Clients /Server Network( เครอขายแบบ Peer-to-Peer (Peer-to-Peer Network) โพรโตคอลของ LAN Ethernet Token Ring 45

Network Operating System, NOS • • • Netware from Novell Microsoft Windows NT Server Microsoft Windows NT 2000 Apple. Share Unix Linux 46

การใชงานระบบเครอขาย • Electronic Mail • Voice Mail • Facsimile • Teleconference • Online Services • Internet 47