1. 1 Prepared and Design By: Mr.AM.Sihan ( lecturer, IDM Computer Studies Kalmunai (Pvt) Ltd.

2. 2 What is a Computer? A Computer is a programmable, multipurpose machine that accepts data and processes, or Manipulates it into information we can use, such as summaries or totals. Characteristics of computers -Speed -Accuracy -Intelligent -Storage Power -No feeling, like human beings. Data Processing Data processing is the collection and manipulation of items of data to produce meaningful information. Data Process Storage Information Input Output Data Processing Stages 1.Origination 2.Preparation 3.Input 4.Processing 5.Output

3. 3 The Functions of a computer system Getting data inputs Storing Control of operations Processing Giving the output The components or devices associated with these functions are: - Input devices - Storage devices - CPU (Central Processing Unit) - Output devices Generation of computers 01 st Generation : Early computers using electronic valves in 1940s. 02 nd Generation : More reliable computers using transistors which replace the first generation I n 1952s. 03 rd Generation : More powerful, Reliable and compact computers using simple integrated circuits in 1962 and early 1970s. 04 th Generation : The computers in use today which contain more sophisticated micro electronic devices such as VLIS. 05 th Generation : They would have ARTIFICIAL INTELIGENCE. That is the would able to imitate common human functions such as vision, natural language comprehension etc. Type of computers *Mainframe computers *Mini computers *Micro computers

4. 4 Basic Components of Computer System Software Hardware Application Software Operating System Packages Microsoft Office Coral Draw Adobe Photoshop AutoCAD….etc Languages Pascal VB Java C++ etc. Windows 3.1 Windows 95 Windows 98 Windows NT Windows 2000 Windows XP Windows Server 2003 Windows Vista Killer Ubundu Linux Input Devices Output Devices CPU Storage Devices Internal Storage Devices External Storage Devices

5. 5 Computer Hardware  What is a computer hardware? The physical components of the computer system that can be touched and tangible called as “Hardware”. It can be classified into parts. Input Devices Output Devices CPU (Central Processing Unit) Storage Devices Input Devices It can be used to input the data the computer. There are wide variety of input devices to input text, graphics, pictures and sound etc… Ex: keyboard, Mouse, Scanner, and Light pen. Type of keyboard PS/2 Keyboard USB Keyboard Serial Keyboard Wireless Keyboard Type of mouse PS/2 Mouse USB Mouse Serial Mouse Wireless Mouse Output Devices It can be used to give the information. There are wide variety of output devices and sounds desired output. Ex: Printers, Speakers, and Monitor (VDU – Visual Display Unit).

6. 6 Central Processing Unit (CPU) The CPU is the main brain of the computer, which provides the fundamental control structure for may computer system. The name CPU is some times used interchangeably with “ processor”, however a CPU contains more than just a processor. The functions of the processor : -To control the use of main storage to store data and instructions. -To control the sequence of operations.\ -To give commands to all parts of the computer system. -To carry our processing. The processor is made up of two major units. 1.The Control Unit (CU) 2.The Arithmetic and Logic Unit (ALU) Control Unit This is the nerve center of the computers, controlling all other hardware operations, those of the input – output units, storage and of the processor itself. It gets the required instructions form main storage, stores it in number of special registers, interprets the instructions and courses the instructions to be executed by giving signals (or commands) to the appropriate hardware devices. Arithmetic and Logic Units The various factors to be processed are taken from the main storage as directed by the CU, and stored in its registers, they are then added, etc. together and the results placed back in main storage.

7. 7 Central Processing Unit (CPU) Type of Processor A.Slot Type Processor B.Socket Type Processor CPU Speed 100 MHz 133 MHz 160 MHz 200 MHz 233 MHz 250 MHz 300 MHz 350 MHz 400 MHz 450 MHz 500 MHz 550 MHz 600 MHz 650 MHz 700 MHz 733 MHz 800 MHz 866 MHz 900 MHz 933 MHz 1000 MHz 1200 MHz 1500 MHz 1700 MHz 1800 MHz 2000 MHz 2400 MHz 2600 MHz 2800 MHz 3000 MHz 3600 MHz PI PII PIII P4 Function of Processor R.U ALU CU InputProcessing Output KeyboardMonitor (VDU) R.U – Register Unit ALU – Arithmetic And Logic Unit CU – Control Unit Company of Processors 1.Intel 2.Cyrix 3.Celeron 4.AMD…etc 800/256/133/1.65V Intel CPU Speed Company Voltage Bus Speed PII, PIII -100MHz, 133MHz. P4 – 233MHz, 333MHz, 400MHz, 533MHz, 666MHz, 800MHz CPU Bus Speed 1 23

8. 8 Bus When referring to a computer, the bus also known as the address bus, data bus, or local bus is a data connection between two or more devices connected to the computer. For example, a bus enables a computer processor to communicate with the memory or a video card to communicate with the memory. A bus is capable of being parallel or a serial bus and today all computers utilize two types of buses,parallelserial an internal or local bus and an external bus. An internal bus enables a communication between internal components such as a computer video card and memory and an external bus is capable of communicating with external components such as a SCSI scanner.video cardmemory A computer or device's bus speed or throughput is always measured in bits per second or megabytes per second.throughputbits per secondmegabytes per second Cache Pronounced as Cash (like the money). Cache is a high-speed access area that can be either a reserved section of main memory or a storage device.memory The two main types of cache are: memory cache and disk cache. Memory cache is a portion on memory of high-speed static RAM (SRAM)RAMSRAM and is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM.DRAM Storage Devices Internal Storage Devices/ Primary Storage Devices External Storage Devices/ Secondary Storage Devices Internal Storage Devices Is also known as primary storage, Main storage, Immediate access storage, and RAM & ROM. [01.] Ram (Random Access Memory) : Short for Random Access Memory, RAM, also known as main memory or system memory, is a term commonly used to describe the memory within a computer. Unlike ROM, RAM requires power; if power is lost, all data is also lost.ROM

9. 9 Type of Ram -Simm -Dimm -Rimm SDR Ram (Static Dynamic Rate) DDR Ram (Dynamic Data Rate) DDR I DDR II Simm (Single In-line Memory Module)lineMemoryModule SIMMSIMM is a circuit board that holds six to nine memory chips per board and were commonly used with Intel Pentium or Pentium compatiblecircuitchipsIntelPentiumcompatible motherboardsmotherboards. Computers utilizing SIMMs were later replaced with computers using DIMMs. Below is a graphic illustration of a 4MB SIMMDIMMgraphic as well as a diagram pointing out the important features of a SIMM.features

10. 10 Dimm (Dual In-line Memory Module) DIMM is a type of circuit board that holds memory chips. DIMMs have a 64-bit path because of the Pentium Processor requirements.64-bit Because of the new bit path, DIMMs can be installed one at a time, unlike SIMMs on a Pentium that would require two to be added. 01. SDR Ram (Static Dynamic Rate) We can see them in pendium II & III It is bus speed - 100MHz, 133MHz 02. DDR Ram (Dynamic Data Rate) We can see them in pendium4 It is bus speed – 266MHz, 333MHz, 400MHz – DDR I 533MHz, 666MHz, 800MHz - DDR II

11. 11 Rimm (Rambus In-line Memory Module) Also see: C-RIMM, DRAM, Memory definitionsC-RIMMDRAMMemory definitions RIMM is not an acronym and is a trademark of Rambus incorporated for the Direct Rambus or DRAM modules. RIMM is a type of computerRambus memory that resembles DIMMs; however, it is 184-pin and is available with built in ECC support and Non-ECC at speeds up to 800MHz. RIMM modules are commonly used on the Intel Pentium 4 motherboards.Intel [02.] Rom / Bios (Read Only Memory / Basic input output system) : BIOS is a chip located on all computer motherboards that contains instructions and setup for how your system should boot and how it operates. To the right is a picture of what a BIOS chip may look like in your computer. The BIOS includes instructions on how to load basic computer hardware and includes a test referred to as a POST (Power On Self Test) that helps verify the computer meets requirements to boot up properly.POST If the computer does not pass the POST, you will receive a combination of beeps indicating what is malfunctioning within the computer.

12. 12 Type of Rom 1.PROM 2.EPROM 3.EEPROM PROM (Programmable Read Only Memory) Short for Programmable Read Only Memory, Programmable ROM, or PROM is a type of computer memory chip capable of being programmed. Once the PROM has been programmed, the information written is permanent and cannot be erased or deleted. EPROM (Erasable Programmable Read Only Memory) Short for Erasable Programmable Read-Only Memory, ERPOM is a memory chip that was invented by Dov Frohman that can be read from but not stored to. However, if exposed to ultraviolet light and can be reprogrammed if needed. Hardware manufactures use EPROM when it may be needed that the data contained on the EPROM needs to be changed. An EPROM chip is easily distinguishable by a small glass circle that exposes the chip that can be reprogrammed.

13. 13 EEPROM (Electrically Erasable Programmable Read-Only Memory ) Short for Electrically Erasable Programmable Read-Only Memory, EEPROM is a type of PROM that can be erased and reprogrammed usingPROM an electrical charge. Unlike most memory inside a computer, this type of memory remembers data when the power is turned off. EEPROM is often used to store information for the computer's BIOS. BIOS

14. 14 External Storage Devices Since main storage is expensive and fixed in supply within a computer system, the practical solution is to limit to the size of main storage and Supplement it with less expensive backing storage. External storage is non – volatile. Ex: HARD DISK (HDD),CD-ROM, FLOPPY DISK, CD, FLASH DRIVE etc. Hard Disk A computer's main storage media device, also called a hard disk drive or abbreviated as HD or HDD. The hard drive was first introducedcomputer's on September 13, 1956 and consists of one or more hard disk platters inside of air sealed casing. Most hard drives are permanently1956platters stored in an internal drive bay at the front of the computer and are connected with either ATA, SCSI, or a SATA cable and power cable.internaldrive bayATASCSISATA Below is an illustration of the inside of a hard disk drive. As can be seen in the above picture of the desktop hard drive the main six components that help make up the inside are thehead actuator, read/write actuatorhead actuatorread/write actuator armarm, read/write head, spindle, and platter.read/write headspindleplatter

15. 15 Data Cable Short for Integrated Drive Electronics or IBM Disc Electronics, IDE is more commonly known as ATA and is a standard interface for IBM compatibleATA hard drives. IDE is different from the Small Computer Systems Interface (SCSI) and Enhanced Small Device Interface (ESDI) because its controllersSCSI are on each drive, meaning the drive can connect directly to the motherboard or controller. IDE and its updated successor, Enhanced IDE (EIDE), are the most common drive interfaces found in IBM compatible computers today. Below is a picture of the actual IDE connector and cable and the back of a hard disk drive that the cable connects to. Master SlaveCS- Cable Select

16. 16 Jumper Settings – CD Rom / HDD Jumper Setting – Master / CS Jumper Setting – Slave / CS

17. 17 CD – Rom Short for Compact Disc-Read Only Memory, CD-ROM drives are CD-Players inside computers that can have speeds in the range from 1x and beyond, and have the capability of playing audio CDs and computer data CDs. Below is a picture of the front and back of a standard CD-ROM drive. Below is an illustration of the back of a CD-ROM for users who may need to have a better example of the pins and/or connectors.

18. 18 Floppy Disk Also known as a floppy, a floppy disk was originally created in the 1960s and 1970s to help help have an alternative to buying hard drives that19601970hard drives were extremely expensive at the time and were not thought of as something to be used with a standard computer. 8" Disk - The first disk was introduced in 1971. The disk was 8" in diameter with a magnetic coating, enclosed in a cardboard case with the1971 capacity of one megabyte. Conversely to hard disks, the heads actually touch the disk, like in a cassette or video player that actually wears the media down over time. 5.25" Disk - Created in 1976 which first started with disks only with 160KB.1976 5.25" Single Side - 160KB 5.25" Double Side - 360KB 5.25" Double Side High Density - 1.2MB 3.5" Disk - Created by IBM in 1987, which even today are still commonly used. Most 3 1/2" newer disks have a capacity of up to 1.44MB.1987 3.5" Double Density - 720KB 3.5" High Density - 1.44MB (See document CH001135 for why it's 1.44MB) 3.5" Extended Density (IBM ONLY) - 2.88MBdocument CH001135 Below is a graphic of a floppy diskette. As can be seen by the below picture, this particular diskette is clear, which enables you to see inside of the diskette. You can notice that the floppy has a circular cloth that is located on both sides of the floppy; this cloth helps clean and protect the magnetic disk within the diskette. Floppy Drive

19. 19 CD Abbreviated as CD, a compact disc is a flat round storage medium that is read by a laser in a CD-ROM drive. The standard CD is capable of holdingCD-ROM 72 minutes of music or 650 MB of data. 80 minute CDs are also commonly used to store data and are capable of containing 700 MB of data.MB

20. 20 Flash Drive Also known as a USB flash drive and thumb drive, a jump drive is a portable drive that is often the size of your thumb that connects to theportabledrive computer USB port. Today flash drives are available in various sizes including but not limited to 256MB, 512MB, 1GB, 5GB, 16GB, and beyondUSB and are widely used as an easy and small way to transfer AND store information from their computer.transferstore To the right is an example picture of the SanDisk Cruzer Micro 16GB flash drive and a good example of what many flash drives look like. As can be seen in this picture the drive has a small casing that stores the flash memory connected to a USB connection that is plugged into the USB port on your computer.

21. 21 Storage Capacity Chart 1 Character-1 Bit 8 Bit-1 Byte 1024 Byte-1 Kilo Byte (KB) 1024 Kilo Byte-1 Mega Byte (MB) 1024 Mega Byte-1 Giga Byte (GB) VGA Short for Video Graphics Array, VGA is a popular display standard developed by IBM and introduced in 1987, VGA provides 640 x 480 resolutionIBM1987resolution color display screens with a refresh rate of 60Hz and 16 colors displayed at a time. If the resolution is lowered to 320 x 200, 256 colors can be displayed. VGA capability is built into plug-in video cards, VGA chips, and monitors that can work with the VGA cards. Today,refreshHz VGA has been replaced by SVGA. Below is an illustration of the 15-Pin VGA connector, its pin assignments, and size dimensions with a chart describing what each of the pins are for. VGA Capacity 3MB 4MB 8MB 16MB 48MB 32MB 64MB 128MB 256MB 512MB 1GB PII PIII P4

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23. 23 Sound Card Also known as a sound board or an audio card, a sound card is an expansion card or integrated circuit that provides a computer with the ability toexpansion cardintegrated produce sound that can be heard by the user either over speakers and/or headphones. Below is an image of the Creative Sound Blaster X-Fi XtremespeakersheadphonesCreative Audio sound card and an example of what a sound card may look like. To the right is an example of what a generic sound card may look like from the back of your computer and the connector symbols usually found next to each of the connections. With almost every sound card you'll have four connections: sound out or line out,sound out or line out sound in or line insound in or line in, Microphone, and MIDI (Joystick).MicrophoneMIDIJoystick You may also find that these ports are color coded as seen in the above picture of a computer sound card. If you're using speakers or other audio peripherals that are also color coded you can easily identify what port to use by matching the colors. Below is a listing of some of the functions of a computer sound card. - Games - Audio CDs - Watch movies - Audio conferencing - Creating and playing Midi - Educational software - Business presentations - Record dictations - Voice recognition

24. 24 Network card Short for Network Interface Card, a NIC is also commonly referred to as a network adapter and is an expansion card that enables a computerexpansion cardcomputer to connect to a network such as a home network and/or the Internet using a Ethernet cable with a RJ-45 connector. To the right is a graphicEthernet cableRJ-45 example of an SMC EZ Card 10/100 PCI network card, a type of network card commonly found in most desktop computers today that do notSMCPCI already have an integrated network on their motherboard. Modem Card A modem is like a telephone for a computer to communicate with other computers over telephone lines. Broadly, a modem’s performance depends on the characteristics of the modem and those of the telephone line it is working with. The condition of telephone lines varies widely across the country. So how your modem works will depend to a large extent on the telephone line. There’re several different types of noise that can happen either individually or in combination in a telephone line. Different modems react differently to these. And there’s no way you can identify which of these conditions affect your line. So nobody can correctly predict which modem will work the best on your line.

25. 25 Heat Sink An electronic device that incorporates either a fan and/or a peltier device that allows a hot device such as a processor to keep cool. There are twodevicefanprocessor types of heat sinks: active and passive. Active heat sinks utilize power and are usually a fan type or some other peltier cooling device. If you are looking to purchase an active heat sink, it is recommended that you purchase fans with ball-bearing motors that often last much longer than sleeve bearings. Passive heat sinks are 100% reliable, as they have no mechanical components. Passive heat sinks are made of an aluminum-finned radiator that dissipates heat through convection. For Passive heat sinks to work to their full capacity, it is recommended that there is a steady air flow moving across the fins. To the right is an example image of a heat sink that is both active and passive.

26. 26 PSU (Power Supply Unit) Short for Power Supply and sometimes abbreviated as PSU, which is short for Power Supply Unit. The PS is an internal hardware component used to supply the components within the computer with power. Besides properly supplying power to the computer and all its internal components,componentscomputerinternal the power supply also converts the AC electrical current found in most standard wall sockets throughout the United States into a lower DC voltageACcurrentsocketsDCvoltage that the computer components use. ATX 240V Floppy HDD / CD-ROM Main board/Motherboard or 6 Pin AT OR Check the ATX Power supply

27. 27 Motherboard The motherboard is the main circuit board inside your PC. Every components at some point communicates through the motherboard, either by directly plugging into it or by communicating through one of the motherboards ports. The motherboard is one big communication highway. Its purpose inside your PC is to provide a platform for all the other components and peripherals to talk to each other. Types of Motherboards The type of motherboards depends on the CPU it was designed for. You can therefore categories motherboards by which socket type they have. e.g. Socket A, Socket 478 etc. The Type of motherboard you buy is very important, as it will need to house your CPU, and they are not interchangeable. When buying a motherboard, it will always tell you what socket type it has. When Buying a Motherboard As everything you have on the PC at some point needs the motherboard, you need to consider these components when buying a motherboard. Foe example, if you have a lot of devices with a PCI interface that you wish to use, there is little point buying a motherboard that only offers you 3 PCI slots. Like wise with memory, you have to make sure that there are enough slots for the amount of memory you have or wish to have. The motherboard also needs the correct type of interface for your Memory, Graphics card, Hard disks and other items as well. You will find that most motherboards offer everything you need however it needs checking on when buying. Its especially important to pay detail to your motherboard if you want to use older components, which a new motherboard may or may not support. The major difference between motherboards that support the same CPU is the model of the chipset (more on the chipset later). Different chipsets offer different performance and different features in terms of memory support, AGP port speed, Multiplier numbers, Bus speeds and much more.

28. 28 Speed of a Motherboard Motherboards have got to be one of the hardest components to measure the speed of. Performance can really only be measured by benchmarking using the same components in several motherboards of the same type. You often find that motherboards with the same chipset have roughly the same performance in real world tests. The minor differences that do occur are down to the quality of the materials used and the quality of the manufacturing The Motherboards speeds that are quoted on the box are maximum supported speeds for other components. For example motherboards will quote the maximum FSB (Front Side Bus) speed. However without a CPU that also supports this speed, it will never be reached. Likewise when it quotes the maximum memory speed. The memory of this speed has to be present.. What is a Motherboard Chipset? A motherboard chipset controls all the data that flows through the data channels (buses) of the motherboard. The primary function of the motherboard chipset is to direct this data to the correct area's of the motherboard, and therefore the correct components. Components of a Motherboard The motherboard contains many connections for all type of components. Motherboards contain expansion slots such as the ISA, PCI, AGP and DIMM sockets. It also contains external connections for your onboard sound card, USB ports, Serial and Parallel ports, PS/2 ports for your keyboard and mouse as well as network and Firewire connections. So the motherboard has a massive part to play in the workings of your PC. Components that you buy all rely on the motherboard to have the correct connections are available and working. Its best to buy a decent motherboard especially if you plan on buying extra's in the future.

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31. 31 Socket type Processor and motherboard Socket PGA 270 – PII Motherboard Socket PGA 370 – PIII Motherboard Socket PGA 423 / 478 – P4 Motherboard Socket A – AMD Motherboard Slot type Processor and motherboard Slot 1 – PII Motherboard Slot 2 - PIII Motherboard Slot A – AMD Motherboard

32. 32 System Software What is an Operating System? An Operating system is a special software program that is loaded into a computer at startup and is responsible for running the computer. It manages all the hardware, and provides an interface between the computer’s hardware and the user. Microsoft Windows Family Windows 3.1 Windows 95 Windows 98 Windows 2000 Windows XP Windows server 2003 Windows Vista Minimum Hardware requirements to install Windows XP 1.Computer with a 300 MHz or higher processor 2.64 MB of Ram (128 MB Recommended) 3.1.5 GB of available hard disk space 4.CD ROM drive or DVD drive 5.Super VGA (800x600) or higher resolution monitor with 256 colours 6.Microsoft mouse or compatible pointing device Windows Vista minimum supported system requirements 1.800 MHz Processor 2.512 MB of system memory 3.20 GB hard drive with at least 15 GB of available space 4.32 MB of graphics memory (Recommended 64 MB) 5.DVD – ROM drive

33. 33 Install windows XP 1. Start the computer from the CD.

34. 34 2. You can press F6 if you need to install additional SCSI adapters or other mass storage devices. If you do you will be asked to supply a floppy disk with the drivers and you CANNOT browse it (or a CD for that matter). Make sure you have one handy.

35. 35 3. If you want, you can press F2 to run the ASR sequence. For that you need a good backup created by the Windows XP backup program, and the ASR floppy disk. If you plan to install a new copy of XP - don't do anything.

36. 36 4. Setup will load all the needed files and drivers.

37. 37 5. Select To Setup Windows XP Professional Now. If you want, and if you have a previous installation of XP, you can try to fix it by pressing R. If not, just press ENTER.

38. 38 6. Read and accept the licensing agreement and press F8 if you accept it.

39. 39 7. Select or create the partition on which you will install Windows XP Professional. Depending upon your existing disk configuration choose one of the following: If the hard disk is unpartitioned, you can create and size the partition on which you will install Windows XP Professional.

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41. 41 If the hard disk is already partitioned, but has enough unpartitioned disk space, you can create an additional partition in the unpartitioned space. If the hard disk already has a partition that is large enough, you can install Windows XP Professional on that partition. If the partition has an existing operating system, you will overwrite that operating system if you accept the default installation path. However, files other than the operating system files, such as program files and data files, will not be overwritten. If you select a new partition during Setup, create and size only the partition on which you will install Windows XP Professional. After installation, use Disk Management to partition the remaining space on the hard disk.

42. 42 8. Select a file system for the installation partition. After you create the partition on which you will install Windows XP Professional, you can use Setup to select the file system with which to format the partition. Windows XP Professional supports the NTFS file system in addition to the file allocation table (FAT) and FAT32 file systems. Windows Server 2003, Windows XP Professional, Windows 2000, and Windows NT are the only Microsoft operating systems that you can use to gain access to data on a local hard disk that is formatted with NTFS. If you plan to gain access to files that are on a local Windows XP Professional partition with the Microsoft Windows 95 or Windows 98 operating systems, you should format the partition with a FAT or FAT32 file system. We will use NTFS.

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44. 44 9. Setup will then begin copying necessary files from the installation point (CD, local I386 or network share). 10. Note: If you began the installation process from an MS-DOS floppy, make sure you have and run SMARTDRV from the floppy, otherwise the copying process will probably last more than an hour, perhaps even more. With SMARTDRV (or if setup was run by booting from CD) the copying will probably last a few minutes, no more than 5 max.

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46. 46 11. The computer will restart in graphical mode, and the installation will continue.

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78. 78 Networking & Configuration What is a Network? Network is an interconnection of computers & other devices, which is used to share resources and for communication. Advantages of Network -Allow sharing Resources. -Use as a communication medium. -Cost effectiveness. -Centralized administration. -High reliability. Scope of Networks Local Area Network (LAN) A LAN connect computers that are located near each other and in same geographical location. For example, two computer connected together in an office or two buildings connected together by a high- speed wire can be considered as a LAN. A corporate network that includes several adjacent buildings can also be considered as LAN. Wide Area Network (WAN) A WAN connects a number of computers located at a grater distance form one another and different geographical locations. For example, two or more computers connecting opposite sides of the world is considered as WAN. A WAN can be made up of a number of Interconnected LAN. The Internet is really a WAN.

79. 79 Type of Local Area Network 1: Server-Based Network Another benefit of server-based networks is that a user can sit down at any workstation, login to the server with his or her userid and password, and have access to all of the network resources. 2: Peer-to-Peer Network A peer-to-peer network is not as expensive, nor as secure as a server-based network. A server is more expensive than a regular workstation plus it requires a network operating system. Since peer-to-peer networks do not use a dedicated server, costs are reduced. Instead of a network operating system, each workstation uses a regular operating system such as Windows 95, 98, NTWorkstation, 2000 Professional, or XP. A peer-to-peer network is not as secure as a server-based network because each computer must be configured with individual userids and passwords.

80. 80 Network topologies Network topology is how network devices connect together. The three major types of network topologies are star, ring, and bus. Keep in mind that a large business may have combinations of these topologies. A topology that combines other topologies is known as a hybrid topology. The most common network topology used today is the star topology because it is used with Ethernet networks. Ethernet networks are the most common type of network. Ethernet technology was developed in the 1970s by Xerox Corp. Each network device connects to a central device, normally a hub or a switch. Both the hub and the switch contain two or more RJ-45 network jacks. The hub is not as intelligent as a switch. The switch takes a look at each data frame as it comes through the switch. The hub is not able to do this. Hub/Switch In a star topology, each network device has a cable that connects between the device and the hub or switch. If one computer or cable fails, all other devices continue to function. However, if the hub or switch fails, the network goes down. The hub or switch is normally located in a central location such as a network wiring closet. Network Figure #4 shows how a star topology is cabled. By looking at how each device connects to a central location, you can easily see why it is called a star. Star Topology

81. 81 More cable is used in wiring a star topology than with the bus topology, but the type of cable used is cheap and this is not an issue for today’s network managers. Star topologies are easy to troubleshoot. If one network device goes down, the problem is in the device, cable, or port on the hub/switch. If a group of network devices goes down, the problem is most likely in the device that connects them together (hub or switch). Look back to Network Figure #4. If Workstation 1, Workstation 2, Workstation 3, Workstation 4, and Workstation 5 cannot communicate with one another, the problem is the switch in the middle. If onlyWorkstation 3 cannot communicate with the other network devices, the problem is in Workstation 3, the cable that connects Workstation 3, or in port 13 on the switch. The ring topology is physically wired (cabled) like a star, but operates differently. The ring topology is used in Token Ring networks. Token Ring is a technology developed by IBM Corp. A token (a special network packet) passes from one network device to the next in a continuous fashion. Token Ring networks are wired like a star, but they operate like a logical ring. Ring Topology The token passes from one workstation to another in a continuous loop. When the token does not contain data, it is known as a free token. As the free token is passed around the ring, any workstation wishing to transmit data takes the token and adds data. The data is sent around the ring until it reaches its destination. No other workstation can accept the data except for the destination network device. Once the data has been transmitted, a free token is placed on the ring again. No workstation can transmit until the free token comes back around the ring.

82. 82 The bus topology is one of the oldest network topologies. All network devices connect to a single cable. If the cable has a break, the entire network is down. Bus topologies are also difficult to troubleshoot when there is a network problem. Bus Topology A mesh topology is not as common as other topologies, but it is used when all network devices connect to each other. Mesh topology is more likely to be used in a WAN (Wide Area Network) rather than a LAN (Local Area Network). Mesh topologies take a lot of cabling, but if a cable breaks, the network still continues to function. An example of a mesh topology is a college that has three main campuses—North, South, and West. Each campus has a connection to the other two campuses. For example, the North campus has a connection to the South and the West campuses. Each campus has important servers to which the other campuses need access. If the North campus to South campus connection breaks, the North campus can still reach the South campus by going through the West campus. Whenever a network can still function after a cable break, the network is said to be fault tolerant. A mesh topology provides the most fault tolerance of any network topology. Mesh Topology

83. 83 Network cabling Networks require some type of medium to transmit data. This medium is normally some type of cable or air (when using wireless networking). The most common types of cable are twisted-pair and fiber-optic, although some very old networks have coax cable. Twisted-pair cable comes in two types, shielded and unshielded. The acronyms used with this type of cable are STP for shielded twisted-pair and UTP for unshielded twistedpair. The most common is UTP. With twisted-pair cable, all network devices connect to one central location such as a patch panel, hub, or switch. If one cable breaks, only the one device fails. Most people are familiar with twisted-pair cable because this type of cable is used in homes for telephone wiring. The type used with networking has eight copper wires. The wires are grouped in colored pairs. Each pair is twisted together to prevent crosstalk. Crosstalk occurs when a signal on one wire interferes with the signal on an adjacent wire. The wires are wrapped in a vinyl insulator. UTP Cable UTP cabling is measured in gauges. The most common measurements for UTP cabling are 22,- 24-, or 26-gauge unshielded twisted-pair cables. UTP cables come in different specifications called categories. The most common are categories 3, 4, and 5. People usually shorten the name Category 3 to CAT 3, or Category 5 to CAT 5. The categories determine, in part, how fast the network can run. Category 3 was mainly installed for telephone systems in many office buildings. CAT 3 is called a voice grade cable, but it has the ability to run up to 10Mbps Ethernet or 16Mbps Token Ring topologies. Networks that run 10Mbps are known as 10BaseT networks. 100Mbps Ethernet networks are known as Fast Ethernet, 100BaseT4, and 100BaseT8. The 100BaseT4 networks use two pairs (four wires) of the UTP cable whereas the 100BaseT8 networks use all four pairs (8 wires). The most common type of UTP is CAT 5. Fairly new categories of UTP cable include CAT 5e, which is designed for 100Mbps on UTP and STP; CAT 6, which is designed for 1000Mbps on UTP and STP; and CAT 7, which is designed for 1000Mbps on UTP, STP, and fiber. UTP and STP cable are used in star and ring topologies. A special type of UTP or STP cable is plenum cable. Plenum is a building’s air circulation space for heating and air conditioning systems. Plenum cable is treated with Teflon or other fire retardant materials so it is less of a fire risk. Plenum cable is less smoke producing and less toxic when burning than regular networking cable; however, plenum cable is more expensive. In order to avoid extra troubleshooting time, most businesses install their network cabling according to the ANSI/TIA/EIA- 568-A or 568-B standard. This standard specifies how far the cable can extend, how to label it, what type of jack to use, and so forth.

84. 84 UTP Wiring Standards STP (Shielded Twisted-Pair) cable has extra foil shielding that provides more shielding. Shielded twisted-pair cable is used in industrial settings where extra shielding is needed to prevent outside interference from interfering with the data on the cable. Token Ring cabling used IDC (IBM-type Data Connector)/UDC (Universal Data Connector) attachments. Thee types of connectors are both male and female. They are sometimes called hermaphroditic connectors. When installing network cabling, it is important to insert the UTP cable fully into the RJ-45 jack and to insert the colored wires in the standardized order. One of the most common mistakes that new technicians make when putting an RJ-45 connector on UTP cable is they put the cable into the RJ-45 connector backwards.

85. 85 RJ-45 Pin Another common mistake is not pushing the wires to the end of the RJ-45 connector. Before crimping the wires into the connector, look at the end of the RJ-45 connector. You should see each wire jammed against the end of the RJ-45 connector. Fiber-optic cable is made of glass or a type of plastic fiber and is used to carry light pulses. Fiber-optic cable can be used to connect a workstation to another device, but in industry, the most common use of fiber-optic cable is to connect networks together forming the network backbone. Copper cable is used to connect workstations together. Then fiber cable is used to interconnect the networks, especially when the network is located on multiple floors or multiple buildings. Fiber-optic cable is the most expensive cable type, but it also handles the most data with the least amount of data loss. The two major classifications of fiber are single-mode and multi-mode. Single-mode fiber-optic cable has only one light beam sent down the cable. Multi-mode fiber-optic cable allows multiple light signals to be sent along the same cable. Multi-mode fiber is cheaper and more commonly used than single-mode fiber and is good for shorter distance applications; but single-mode fiber can transmit a signal farther than multi-mode and supports the highest bandwidth. The two most common types of connectors used with fiber-optic cable are ST and SC.

86. 86 Fiber-Optic Connector Types Fiber-optic cabling has many advantages including security, long distance transmission, and bandwidth. Fiber-optic cabling is used by many government agencies because of the high security it offers. Light signals that travel down fiber are impossible to detect remotely, unlike signals from other cable media. Also, because light is used instead of electrical signals, fiber-optic cable is not susceptible to interference from EMI- or RFI- producing devices. Each fiber-optic cable can carry signals in one direction, so an installation normally has two strands of fiber-optic cable in separate jackets. Fiber is used in the ring and star topologies. Fiber-Optic Cable

87. 87 Single-mode cable is classified by the size of the fiber core and the classing. Two common sizes are 8/125 and 9/125 microns. The first number represents the size of the core; the second number is the size of the cladding. Single mode cable allows for distances up to 10,000 meters (which is more than 32,000 feet or six miles). Multi-mode cable (62.5/125 microns) on the other hand, can support distances up to 2,000 meters or over a mile. The last type of cable is coaxial cable (usually shortened to coax). Coax cable is used in older Ethernet 10Base2 and 10Base5 networks as well as mainframe and minicomputer connections. Most people have seen coax cable in their homes. The cable used for cable TV is coax cable, but is a different type than network cabling. Coax cable has a center copper conductor surrounded by insulation. Outside the insulation is a shield of copper braid, a metallic foil, or both, that protects the center conductor from EMI. Network Figure #12 shows a coax cable. Coax is used in star and bus topologies. Coax Cable with Connector

88. 88 Coax Cable Types OSI MODEL The International Standards Organization (ISO) has developed a model for network communications known as the OSI (Open Systems Interconnect) model. The OSI model is a standard for information transfer across the network. The model sets several guidelines including (1) how the different transmission media are arranged and interconnected, (2) how network devices that use different languages communicate with one another, (3) how a network device goes about contacting another network device, (4) how and when data gets transmitted across the network, (5) how data is sent to the correct device, and (6) how it is known if the network data was received properly. All of these tasks must be handled by a set of rules and the OSI model provides a structure into which these rules fit.

89. 89 Can you imagine a generic model for building a car? This model would state that you need some means of steering, a type of fuel to power the car, a place for the driver to sit, safety standards, and so forth. The model would not say what type of steering wheel to put in the car or what type of fuel the car must use, but is just a blueprint for making the car. In networking, the OSI model is such a model. The OSI model divides networking into different layers so that it is easier to understand (and teach). Dividing up the network into distinct layers also helps manufacturers. If a particular manufacturer wants to make a network device that works on layer 3, the manufacturer only has to be concerned with layer 3. This division makes networking technologies emerge much faster. Having a layered model also helps to teach network concepts. Each layer can be taught as a separate network function. The layers of the OSI model (starting from the top and working down) are application, presentation, session, transport, network, data link, and physical. OSI Model Layers Each layer of the OSI model uses the layer below it (except for the physical layer which is on the bottom). Each layer provides some function to the layer above it. For example, the data link layer cannot be accessed without first going through the physical layer. If communication needs to be performed at the third layer, (the network layer), then the physical and data link layers must be used first. Certification exams contain questions about the OSI model and knowing the levels is a good place to start preparing for the exams. A mnemonic to help remember the OSI layers is: A Person Seldom Takes Naps During Parties. Each first letter of the mnemonic phrase is supposed to remind you of the first letter of the OSI model layers.

90. 90 NETWORK PROTOCOLS A network protocol is a data communication language. There are three primary network protocols used: TCP/IP, NetBEUI, and IPX/SPX. TCP/IP (Transport Control Protocol/ Internet Protocol) is the most common network protocol and is used when accessing the Internet. Most companies (and homes) use TCP/IP as their standard protocol. IPX/SPX (Internet work Packet Exchange/Sequenced Packet Exchange) is used when connecting to a Novell network, but Novell networks now use TCP/IP as their standard protocol. NetBEUI (NetBIOS Enhanced User Interface) is a non-routable network protocol. This means that it can only be used on simple networks, not on multiple networks that are tied together. A common place for NetBEUI is on a peer-to-peer network. Another network protocol is AppleTalk. AppleTalk was used with Apple Macintosh computers. Apple computers today use TCP/IP. NETWORK ADDRESSING Network adapters normally have two types of addresses assigned to them—a MAC address and an IP address. The MAC address is used when two network devices on the same network communicate with one another. The MAC address is a 48-bit unique number that is burned into a ROM chip located on the NIC and is represented in hexadecimal. A MAC address is unique for every computer on the network. However, the MAC address has no scheme to it except that the first three bytes represent the manufacturer. The MAC address is known as a layer 2 address.

91. 91 The IP address is a much more organized way of addressing a computer than a MAC address and it is sometimes known as a layer 3 address. The IP address is a 32-bit number that is entered into a NIC’s configuration parameters. The IP address is used when multiple networks are connected together and when accessing the Internet. The IP address is shown using dotted decimal notation, such as 192.168.10.4. Each number is separated by periods and represents eight bits, and the numbers that can be represented by eight bits are 0 to 255. IP addresses are grouped into classes. It is easy to tell which type of IP address is being issued by the first number shown in the dotted decimal notation. Class A addresses have any number from 0 to 127 as the first number; Class B addresses have any number from 128 to 191 as the first number; and Class C addresses have numbers 192 through 223. For example, if a computer has an IP address of 12.150.172.39, the IP address is a Class A address because the first number is 12. If a computer has an IP address of 176.10.100.2, it is a Class B IP address because the first number is 176. An IP address is broken into two major parts—the network number and the host number. The network number is the portion of the IP address that represents which network the computer is on. All computers on the same network have the same network number. The host number is the portion of the IP address that represents the specific computer on the network. All computers on the same network have unique host numbers or they will not be able to communicate. The number of bits that are used to represent the network number and the host number depends on which class of IP address is being used. With Class A IP addresses, the first eight bits (the first number) represent the network portion and the remaining 24 bits (the last three numbers) represent the host number. With Class B IP addresses, the first 16 bits (the first two numbers) represent the network portion and the remaining 16 bits (the last two numbers) represent the host number. With Class C IP addresses, the first 24 bits (the first three numbers) represent the network portion, and the remaining eight bits (the last number) represent the host number. IP Addressing (Network Number and Host Number)

92. 92 In order to see how IP addressing works, it is best to use an example. A business has two networks connected together with a router. On each network, there are computer workstations and printers. Each of the networks must have a unique network number. For this example, one network has the network number of 193.14.150.0, and the other network has the network number of 193.14.151.0. Notice how these numbers represent a Class C IP address because the first number is 193. With a Class C IP address, the first three numbers represent the network number. The first network has a network number of 193.14.150 and the second network has a network number of 193.14.151. Remember that each network has to have a different number than any other network in the organization. The last number of the IP address will be used to assign each different network device its own IP address. On the first network, each device will have a number that starts with 193.14.150 because that is the network number and it stays the same for all devices on that network. Each device will then have a differentnumber in the last portion of the IP address, for example, 193.14.150.3, 193.14.150.4, 193.14.150.5. On the second network, each device will have a number that starts with 193.14.151 because that is the network number. The last number in the IP address changes for each network device, for example, 193.14.151.3, 193.14.151.4, 193.14.151.5, and so forth. No device can have a host number of 0 because that number represents the network and no device can have a host number of 255 because that represents something called the broadcast address. A broadcast address is the IP address used to communicate with all devices on a particular network. So, in the example given, no network device can be assigned the IP addresses 193.14.150.0 or 193.14.151.0 because these numbers represent the two networks. Furthermore, no network device can be assigned the IP addresses 193.14.150.255 or 193.14.151.255 because these numbers represent the broadcast address used with each network. An example of a Class B broadcast is 150.10.255.255. An example of a Class A broadcast is 11.255.255.255. IP Address Information

93. 93 IPCONFIG FTP(File Transfer Protocol) HTML (Hypertext Markup Language) HTTP(Hypertext Transfer Protocol) FDDI (Fiber Distributed Data Interface) POP (Point of Presence) or (Post Office Protocol) SNMP (Simple Network Management Protocol) TCP (Transmission Control Protocol) UDP (User Datagram Protocol) Thank you