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CHAPTER ONE1.0 THE STUDENT’S INDUSTRIAL WORK EXPERIENCE SCHEME

(SIWES)

The Students Industrial Work Experience Scheme (SIWES) was setup especially for undergraduates in tertiary institutions. The Scheme’s main aim is to give students an opportunity to get a glimpse of the out side world by enabling them put in practice what they have learnt in school, in private or in government established bodies and companies. The SIWES program helps to mould and build the character of the students in order to face the future.

MEANING OF SIWESThe Student Industrial Work Experience Scheme (SIWES) is the accepted skills training programme, which forms part of the approved minimum Academic standards in the various degree programmes for all the Nigerian universities. It is an effort to bridge the gap existing between theory and practice of Engineering and Technology, Sciences, Agriculture, Medical, Management and other professional educational programmes in the Nigerian tertiary institutions. It is aimed at exposing students to machines and equipment, professional work – methods and ways to safeguarding the work areas and workers in industries and other organization. The minimum duration for the SIWES should normally be 24 weeks except for Engineering and Technology programmes where the minimum duration is supposed to be 40 weeks as a result of what the students in this field are expected to know or learn during industrial training. The scheme is a tripartite programme, involving the students, the universities and the industry (employers of labour). It is funded by the federal Government of Nigeria and jointly coordinated by the Industrial Training Fund (ITF) and the National Universities Commission (NUC).

OBJECTIVES OF SIWESSpecifically, the objectives of the students’ industrial work experience scheme are to: Provide an avenue for students in the Nigerian Universities to acquire industrial skills and experience in their course of study;Prepare students for the work situation they are likely to meet after graduation;Expose students to work – methods and techniques in handling equipment and machinery that may not be available in the universities;Make the transition from the university to the world of work easier, and thus enhance students’ contacts for later job placement;Provide students with an opportunity to apply their theoretical knowledge in real work situation, thereby bridging the gap between university work and actual practice; and Enlist and strengthen employers’ involvement in the entire educational process of preparing university graduates for employment in industry.

PHILOSOPHY OF JOB SPECIFICATION FOR SIWESTo facilitate the full realization of the objectives of SIWES, it is essential to ensure the proper training of the university students in preparing them for the world of work. One important instrument for maintaining uniformly high and consistent standard is the provision of university – wide job specification for each programme. Job specification is therefore the breakdown of, or packaging of, a discipline into various tasks and task-elements, which would serve as, a major guide not only for the students on industrial attachment but also for the

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industrialists. Thus job specification involves the itemization of the tasks the university students are expected to perform, while on industrial attachment along the lines of the theoretical knowledge imported in the classrooms.

THE ROLE OF THE FEDERAL GOVERNMENTThe activity of government toward providing the opportunities to students on industrial training scheme is indispensable. This can be achieve through the following means:Make adequate funds available to the Federal Ministry of industry to fund the scheme;Make it mandatory for all ministries, companies and Government parastatals, to offer attachment places to students;Make it a policy to include a clause in every major contract costing over six to nine months being awarded for contractors to take student on attachment.

THE ROLE OF THE INDUSTRIAL TRAINING FUND (ITF)Provide logistic material needed to administer the scheme.Compile lists of employers and available training places for industrial attachment and forward such lists to the co-ordinating Agencies (like: NUC, NBTE, NCCE);Organise bi-annual conferences and seminars on SIWES.

THE ROLE OF THE CO-ORDINATING AGENCY (NUC)Establish SIWES co-ordinating Units;Appoint full-time industrial co-ordinators to operate the scheme at Agency Level;Evolve a minimum national guide programme for supervised industrial training activities for approved SIWES courses;Vet and approve SIWES master and placement lists and forward to ITF;In collaboration with the ITF, compile a list of employers for institutions placement lists.

THE ROLE OF INSTITUTIONS (UNIVERSITIES)Establish SIWES co-ordinating units and appoint Department/Faculty for effective training and supervision; Supervisors should not handle more than ten students at time;Control and discipline students like permanent SIWES co-ordinators within the institution;Appoint full-time industrial co-ordinators to operate the scheme at institutional level;Prepare and submit master and placement list to the respective co-ordinating agency and ITF;Place students on attachment with employers;Organize orientation programmes for students to prepare them for industries training. ITF representative may be invited to give a talk to the students during the orientation programme.Work at industrial tailor–made programme with the employers – based supervisor on the National Industrial Training guidelines for each course.Supervise students on attachment and sign their log-book. A minimum of three visits should be made to the students by the institution’s supervisor during the period of attachment;Assess students’ performance and award grades accordingly;Submit complete ITF form 8 to the ITF at the end of the programme;Maintain separate account books for SIWES;Submit comprehensive reports on the scheme to the ITF after the programme.

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THE ROLE OF STUDENTSBe regular and punctual at respective place of attachment;Comply with the employers rules and regulations;Keep proper records of training activities and other assignments in the log-book;Arrange their own living accommodation during the period of attachment;Submit to ITF through their employer form SPE 1;Submit to ITF through their institutions the evaluation Report Form and duly completed by the students, employers and the institutions.

ROLE OF EMPLOYERSAccept students and assign them to relevant on the job training;Attach experienced staff to students staff;Pay students’ monthly allowances as and when due, that is arrange it in form stipend;Provide medical cure for students with in the limits of the employers’ conditions of service during attachment;Follow joint tailor-made programmes during the period of industrial training.Permit representatives of ITF and institutions’ – based supervisor to visit the students of attachment.Grade students, as provide in the assessment form and the ITF form and at the end of the programme and submit same to the institutions.

HISTORY OF PPMCThe Pipelines and Products Marketing Company (PPMC) was one of the subsidiary units (SBUs) created in March 1988 when the Nigerian National Petroleum Corporation (NNPC) for the purpose of proper capitalization and commercialization. Up till 1965, when the nation’s first refinery was established by the Shell and British Petroleum, petroleum used in the country was imported. This continued even till after the refurbishment of the old Port Harcourt refinery. The story has changed quite a lot today. The emergence of PPMC into the scene has ensured among other things the availability of products for sustenance of the nation’s economy. With PPMC in place, marketing companies (major and independent) now distribute products to every nook and cranny of the country after receiving supply from PPMC.

OBJECTIVES OF PPMCThe PPMC was set up with the major objective of providing excellent customer service through the transportation of crude oil to the refineries and moving of white products to the existing and future markets through a safe and well-maintained network of pipelines and depots at a considerable low cost. Part of this subsidiary’s objective include the efficient marketing of petroleum products in the domestic as well as export markets particularly in the ECOWAS sub region, provide marine services and maintain uninterrupted movement of petroleum products from the local refineries. The vision of this NNPC subsidiary may be summarized as follows:To be the dominant of all refined products to the existing domestic and growing export markets within the West African sub regions.To ensure the security of supply of petroleum products to the domestic markets at low operating costs.

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Market special products competitively in the domestic and international markets.Provide excellent customer service by effective and efficient transportation of crude oil to the refineries and moving petroleum products to the markets.

The key elements of this vision is well defined as follows:Efficient transportation of crude oil to the refineries.Efficient and effective evacuation of refined products from the refineries.Security of supply of petroleum products to existing markets.Safe operation at minimal costCompetitive marketing of special products.

MANAGEMENT POLICYIn 1993, the NNPC introduced a new policy system that all business and service units in the group embrace Total Quality Management (TQM), which ensures sustainable growth and survival. PPMC has always from the onset of TQM been guided by the Total Quality culture and thus seeks to provide goods and services that meets and exceeds the desires of customers. PPMC staff and management are totally committed to this course.

PPMC STRUCTUREPPMC is structured to operate under a board of directors headed by a non-executive chairman. A chief executive officer who is assisted by two executive directors in charge of Operations and Services respectively does the daily management. The Managing Director and the two executive directors are members of the board, which consists of ten members, with the company secretary/legal adviser as secretary of the board. The other members of the board include: the Managing Director Finance and Accounts, Managing Director Commercial, Head of Internal Audit and Managing Director Material Management. They all report to the Managing Director.

MODE OF OPERATIONPPMC receives crude oil from a unit of NNPC called National Investment Management Service (NAPIMS). PPMC then supplies the crude oil to the NNPC local refineries. Petroleum products refined locally are received by PPMC for onward distribution through pipelines to depots. Sometimes petroleum products are imported when local refineries cannot process enough for the country’s needs. Such imported products are received through import jetties by the PPMC. From the various distribution depots, tankers lift these products to designated retail outlets. There is even provision for using rail to move products form some PPMC depots.

PRODUCT PIPELINES AND DEPOT SYSTEMPPMC executes its major assignment through a network of petroleum products pipelines and storage depots strategically located nationwide. The products pipelines, which span a total length of 4950km, are used for moving products, with mainline and booster pumps installed along the pipeline to facilitate the pumping of white products. The multi-products pipelines, which operates, is an integrated system and it links all depots and refineries. It also links all import reception facilities. The storage depots include the following depots: Aba, Enugu, Markurdi, Yola, Warri, Benin, Ore, Ibadan, Mossimi, Lagos, Satellite (Ejigbo), Atlas Cove (Takwa Bay), Suleija, Minna, Kaduna, Kano, Gombe, Gausa, Jos, maiduguri and Calabar.The products pumped are:

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PMS (Premium Motor Spirit) Automobile Gas Oil (AGO) Dual Purpose Kerosene (DPK)Liquefied Petroleum Gas (LPG)Aviation Turbine Kerosene (ATK)Aviation Turbine Kerosene (ATK) is pumped from Mossimi to Ikeja Airport.

AREA OFFICESThe pipelines and storage depot systems along with its mainline and booster pumps and import/export facilities are administered under five zones known as Operational Areas. Each operational area has an administrative office known as Area Office within the area under its control and an Area Manager who reports directly to the Executive Director Operations heads it. The five area offices are:Area Office In Charge Of H/QPort Harcourt PH Depot Port Harcourt

Okrika JettyAba DepotEnugu DepotMarkurdi DepotCalabar DepotBonny export terminal

Warri Warri Depot WarriWarri JettyAuchi Pump StationLokoja Pump StationAbudu Pump StationBenin DepotEscravos Terminal

Mossimi Mossimi Depot MossimiAtlas Cove DepotSatellite (Ejigbo) DepotIbadan DepotOre DepotIlorin Depot

Kaduna kaduna Depot KadunaAbaji Pump StationIzom Pump StationMinna DepotSuleija DepotSarkin Parwa pump StationZaria Pump StationKano Pump StationGuasau Pump Station

Gombe Jos Depot Gombe

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Gombe DepotYola DepotBiu DepotMaiduguri Depot

WARRI AREA OFFICELocated adjacent to the Warri Refining and Petrochemicals Company, in Ekpan Warri, the Warri area office of the PPMC where I did my six-months industrial training is the area office in charge of the following units: Warri Depot, Warri Jetty, warri Pump Station, Auchi Pump Station, Abudu Pump Station, Benin Depot and Escravos Terminal.PPMC under Warri Area Office directly receives crude oil from the NNPC Chevron Joint Venture Crude oil terminal in Escravos. The crude oil is sent to the Warri refinery for processing. White products are received by PPMC (Warri Area) from Warri refinery for onward distribution to all depots within the Warri Area through its pipeline network. Crude oil is also pumped directly from Warri to Kaduna refinery.

In compliance with its culture of Total Quality in its service delivery, Warri Area office of the PPMC is well structured. The major departments obtainable in Warri Area Office of the PPMC are:Finance and Accounts (FAD) Department.Admin and Personnel (APD) DepartmentOperations (OPS) Department.Maintenance Department.Audit Department.Research and Intelligence Department.

Each departmental head reports directly to the Area Manager. The departmental heads also called Deputy Manager (DM) are solely responsible for overseeing of all sub units within that department.

MAINTENANCE DEPARTMENTMaintenance department is solely responsible for all forms of engineering/technical activities carried out within the area office. Activities carried out maintenance department could range from installation new systems (materials, machinery, etc.), repairs, overhaul and sometimes, preventive maintenance on existing equipments. Typical day to day jobs carried out in maintenance department include: building up structures, servicing/repairing of mainline and booster pumps, servicing official vehicles, computer installation and maintenance, computer network maintenance, repair of broken (vandalized) pipelines, etc.

In order to achieve effective coverage of all engineering/technical activities carried out in the Warri Area Office of the PPMC, the Maintenance department is divided into the following sub departments:ElectricalTelecom/InstrumentationMechanicalPlanningCorrosionCivil

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Each of this sub department is headed by a Superintendent (Supt.) who reports directly to the DM Maintenance and is solely responsible for the co-ordination of all the activities in that sub unit.

THE INFORMATION TECHNOLOGY UNIT (ITU)I was immediately deployed to the Information Technology Unit (ITU) when I started my six-month SIWES training program in the Warri Area Office of PPMC in June 2004. ITU is a unit under Planning sub department of Maintenance Department. A systems/network engineer who reports directly to the Planning Superintendent heads this unit. A wide range of computer related activities are carried out in this ITU. Such activities may be classified into three categories: hardware, software and networking. In compliance with the Total Quality Management (TQM) principle, PPMC and of cause, NNPC in general employs systems and network engineers who are professionals and with certifications from software and network giants like Microsoft and Cisco into ITU. Besides, management ensures that they undergo successive training and retraining in order to meet up with the ever-changing trends in the IT industry.

1.10 ORGANIZATIONAL CHART OF MAINTENANCE DEPARTMENT OF PPMC WARRI AREA

CHAPTER TWO

HARDWARE ACTIVITIES IN ITU

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The Information Technology Unit (ITU) of PPMC Warri is solely responsible for all computer related activities in the Warri Area Office of PPMC. The bulk of the activities carried out in IT unit during my six-month period on industrial attachment were basically hardware-related. Such activities or hardware jobs could be grouped into two main categories:Computer InstallationComputer Maintenance (Preventive and Corrective) Before taking a detailed look at these groups of activities, let us first familiarize ourselves with the basic components that make up the microcomputer system. It is one or more these basic components that is installed, replaced or repaired during PC assembly, upgrading or troubleshooting.

THE BASIC PARTS OF THE COMPUTER SYSTEM

The computer system is made up of several parts or components so in order to add, modify and remove system components (installation and maintenance) one has to be able to identify the basic parts that make up a computer system. These parts come in various sizes and shapes, and also in different forms in terms of hardware and software related features.Some basic parts of the computer system are as stated below.MotherboardProcessorPower supply unitRAM (Random Access Memory)Hard diskFloppy driveCD-Rom driveKeyboard and mouseMonitorCasing

A. MOTHERBOARDThe motherboard otherwise called the system board could be defined as a board made of fiberglass or otherwise used in interconnecting other components and peripherals within a computer or electronic system. All of the parts that go into building a computer have a direct connection to the motherboard. The motherboard, besides serving as the traffic cop for routing information to all the parts, also serves as the home of the brain (CPU) and the memory (RAM), which fit into special sockets. A lot of terminology is used to describe different flavors of motherboards and their capabilities, but most variations have little real impact on the user.The motherboard comes in different sizes, shapes and forms; according to the manufacturers specification and thirst. Fig 2.1 shows a typical diagram of a motherboard already affixed into a system casing with the power supply present.Fig 2. 1 (a) Motherboard Mother board could also generally be classified according to the type of processor that can fit into it (PGA, Slot, etc), the type of power that can make the board come up (in terms of AT and ATX power cables) and the number of already built circuits found on the motherboard (on board devices).

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Fig.2.1a: Motherboard B. PROCESSOR OR CPUThe processor otherwise called the Central Processing Unit is a circuitry device in form of a chip, which acts as the brain of the computer. The processor also comes in different sizes and models. The processor comes in several physical forms. Older processors like the 286, 386, 486 are now obsolete. Pentium now replaces them, with the chips in the PGA format (Pin Grid Array). There are also other processors that come in a slot form. This slot form is also becoming obsolete. Processors are characterized by the speed in which they perform. The primary figure of merit for a CPU is the clock speed, measured in MHz (Megahertz). Speeds of processors ranges from a few MHz (million Hetz) to several GHz (Giga Hertz). Fig 3.6 below shows a typical diagram of a PGA processor. Processors also come in different sizes according to the type of port they would fit into. Such ports as the socket 7,socket 5,socket 370, etc.

C. POWER SUPPLY UNITThe power supply unit is found at the exterior end of the computer system. The power supply performs two jobs insides the box. One is to supply power to the motherboard in a wide variety of voltages, and the other is to provide power to the drives and other internal devices. This unit is responsible for providing power to the system; i.e. it converts AC voltage into DC voltage, which powers the components found within the computer system. This unit normally comes in two different types called the AT and ATX. The ATX power unit is a modified form of AT in terms of digital and power saving features. Power supply units normally come already attached to the casings of a system. The power cords that power the motherboard of the AT and ATX are different.

Fig 2.1c: Power Supply Unit

Fig 2.1c(i) shows a typical power cords for the motherboards of an ATX motherboard. Fig 2.1c also shows a typical diagram of a power supply unit Fig 2.1c (i): ATX power cord

D. RAMRam is an acronym for Random Access Memory, and it is a memory device used in electronic gadgets for storing information or data temporarily. It could also serve as a bridge between users and the hard drives found in a system.

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This then means that the CPU never looks directly at the information on your floppy disk or your hard drive. This information is copied into memory by one of the traffic cops on the motherboard. The CPU then reads this information from the memory and acts on it. Random Ahen it starts. If the LAN card is not automatically detected and the required drivers installed, then the following steps are taken to install the LAN card drivers:

Insert the driver floppy that came along with the LAN card into the floppy disk drive.Right-click on My Computer icon on the desktop and click on Properties from the drop-down menu.On the My Computer properties dialog box, click on hardware options to display the Hardware tab.From the Hardware tab, click on Device Manager button. Right click on the improperly installed LAN card (e.g. SIS 900 PCI Fast Ethernet Adapter) and click on Update Drivers from the popped-up menu options.The Add Hardware wizard starts up. Select the “Install From a specific location” option and click next to continue.In the next window ensure that the “Search Removable Media (floppy, CD-ROM)” is checked. Click the next button. The wizard then searches for the drivers from the driver floppy and installs the LAN card. Click Finish to complete the installation.

INSTALLING PCI VGA CARDInstalling a VGA card is a lot similar to the installation of any other PCI adapter card. The first step in the installation process is basically familiarizing your self with the documentation that came with your PCI adapter. Open the cabinet to expose the PCI connector on the motherboard and carry out the following steps:Locate an empty PCI slot. Remove any back cover plate on the empty slot. Install the PCI adapter: Align the VGA adapter with the PCI slot Carefully insert the card into the PCI slot on the motherboard Secure the card with a screw.

Fig: 2.3.5: PCI VGA card

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RANDOM ACCESS MEMORY (RAM)Random Access Memory (RAM) is the main memory of the microcomputer system. Two categories of RAM chips are available: DRAM (Dynamic RAM) and SRAM (Static RAM). DRAM are made from IC capacitor which loose their charges overtime As a result DRAM needs to be continuously refreshed every few milliseconds even while power is still available to the chip. They however offer greater storage capabilities than SRAM which are made from IC transistors and thus do not require continuous refreshing like DRAM chips. They retain the data stored on them as long as power is available to the chip. However they can only store about 25% as much data in a given size as a DRAM chip. DRAM and SRAM uses several technologies in present day microcomputer systems. The most common DRAM technologies today are: Direct Rambus RAM and Double Data Rate Synchronous Dynamic RAM (DDR SDRAM or SDRAM II). Most SRAM are now inside the processor housing or are on-board chips. DRAM modules on most present day motherboards are stored in DIMMs, which use special snap-in sockets to firmly support the module vertically on the board. Typical DRAM IC’s in present day microcomputer systems come in sizes ranges in the order of 32MB, 64MB, 128MB, 256MB, 512MB and 1GB.

Fig: 2.3.6 SDR DDRAM Module

INSTALLING/UPGRADING RAMInstallation is a simple hardware process. As already stated RAM modules used in modern Pentium boards are essentially DRAM chips, which are stored either as SIMMs, DIMMs. Most ally have both SIMM and DIMM banks. Installing a DRAM chip simply entails carefully snapping it into the SIMM or DIMM bank, depending on the type of DRAM module. SIMM modules can only be inserted in one direction because of the safety tab at one end of the SIMM slot. To install a SIMM module, insert the module into the slot at a 45-degree angle making sure that all contacts are aligned with the slot. Rock the slot into a vertical position so that it snaps into the plastic and the plastic guides go through the SIMM’s mounting holes. The metal clip then locks into place. To release the SIMM, gently push the metal clip outwards and rotate the SIMM out of the slot. DIMM modules just slide vertically into the socket and are locked in place by a tab at each end. When installing more than one DRAM chips, Bank 0 is usually filled first before Bank 1 and so on.Upgrading the system’s RAM is also a fairly simple process. Having more RAM on-board allows the system to access extended or expanded memory without havingdrive. This speeds up operation considerably. Updating RAM normally entails installing new memory modules in vacant SIMM or DIMM banks. If the banks were already populated, it will be necessary to remove them and install faster or higher capacity modules.

BASIC INPUT OUTPUT SYSTEM (BIOS)BIOS is a set of essential software routines that test hardware at startup, start the operating system, and support the transfer of data among hardware devices. The BIOS is stored in read-only memory (ROM) so that it can be executed when you turn on the computer. Although critical to performance, the BIOS is usually invisible to computer users. BIOS represent the computer’s intelligence at start-up. PC system boards use one or two ROM IC chips to hold

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the system’s BIOS firmware. In the system memory map, memory locations E0000H to FFFFFH are mapped for BIOS routines. Such BIOS typically include programs that handle start-up of the system, controls video and printer output and carry out Power-On Self Test (POST). When a power-up or manual reset occurs in the computer system, it clears most of its registers to 0. However, the Instruction Pointer (IP) is set to 0FFF0H and the Code Segment register to F0000H. This gives the physical address of the first instruction as FFFF0H. This address is in the ROM BIOS program memory area. This is aimed to ensure that when the computer starts up, it must begin taking instruction from this ROM location to initialize the system for operation. The first BIOS routine executed at start-up is the Power-On Self Test (POST). During the POST program, the first test that is carried out is on the BIOS itself. This is known as the ROM BIOS Checksum test, which verifies the accuracy of the BIOS program. This is followed by a number of tests on DRAM tests (which verify the bits in memory) and CMOS RAM tests (to ensure that it’s values have not changed as a result of power failure). During these memory tests, POST displays a running memory count to show that is testing and verifying the individual memory locations. Sequentially the system interrupt is disabled, the bits of the microprocessors flag registers are set and a Read/write test is performed on each of its internal registers. After testing and verifying the microprocessor’s internal registers, the BIOS program begins the initialization of the rest of the system by handing over control to the BIOS chip itself. At this point, BIOS checks if either a cold boot or a warm boot was carried out. If a Cold boot was indicated, BIOS tests the first 16KB of RAM, before going on to initialize the system’s intelligent devices. During this part of the program, start-up values stored in ROM chips are moved into the system’s programmable devices to make them functional. In particular, the interrupt, DMA, keyboard and video controllers are programmed.

POWER SUPPLIESThe Power Supply Unit provides electrical power for every component inside the system unit as well as to the video display monitor. It converts commercial power received from a 120V (AC), 60HZ (220V (AC), 50HZ, outside the United States) outlet into other levels required by the components in the system unit. 2.3.8.1 AT AND ATX POWER SUPPLIESThere are two types of power supply units: the AT and ATX. The traditional AT power supply, which was designed to support the older AT compatible system boards, uses two six-pin system board power connectors (P8/P9) to connect to the system board. It typically produces four different efficiently regulated DC voltage levels: +5V, -5V, +12V and –12V. The cooling fan of the AT power supply pulls air through the case and exhausts it out the rear of the power supply unit. The ATX power supply on the other hand, is designed to support the newer ATX design specification. Unlike the ATX power supply, it uses a single 20-pin power connector (P1) to connect to the system board. In addition to the DC voltage levels provided by the AT power supply, the ATX power success Memory (RAM) is called by this name because the CPU can get information from any location in the memory in much less than a millionth of a second. RAM could be classified according to its type, capacity and form. It comes in different types and sizes, ranges from the obsolete SIMM (Single In-line Memory Module) to the current DIMM (Dual In-line memory module). Since RAMS are memory devices, the amount of data stored in them is measured in bytes. The capacity ranges from a few megabytes to several gigabytes as the case may be.

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RAMS could also be classified according to the number of processing elements it can accommodate within this context there are DRAMS and SDRAMS. Sizes of RAMS ranges from 32MB, 64MB, 128MB, 256MB, 512, etc. Fig 2.1d below shows a typical diagram of a RAM.

RAM could also be classified according to the number of pins they have (connecting surfaces). It has been noticed that the more the pins the larger and faster the RAMS would be

E. HARD DISKThis could be defined as a non-removable media that provides the permanent storage for your computer. When the computer is turned off, all of the parts except for the drives and ROM are effectively wiped clean. Hard drives use electric motors to spin disks or tapes, and require a power lead directly from the power supply. For instance there are the SCSI and IDE hard drives available in the market. Hard drives are measured in bytes, and the capacity of hard drives found in the market ranges from a few million bytes (MB) to several giga bytes (GB). Such hard drives ranges from 500MB, 1GB, 10GB, 20GB, 80GB, etc. fig 2.1d below shows a typical diagram if an IDE hard drive.

Fig 2.1(e): Hard Disk

F. FLOPPY DRIVE

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Floppy drives are drives that aid in the recording of information onto thin magnetic disks. Floppy drives and floppy disks come in two sizes: the older, flexible, 5 1/4" disks and the newer, rigid, 3 1/2" disks. Floppy disks, which are read by a floppy drive, provide permanent, removable storage for your computer. The storage is permanent, because it is recorded in the magnetic material of the disk the same way that audio or videocassettes are recorded. The disk capacity of floppy drives ranges from 1.44MB to 2.88MB.Fig 2.1h shows a typical diagram of a floppy drive.

G. CD-ROM DRIVE

The CD-ROM is an acronym for Compact Disk Read Only Memory. And this is a hardware device that enables the storage of information on circular disk. The CD –ROM drives could come in different forms such as the Photo drives, RW (read/write) drives, etc. Multiples of X could be used to denote the speed at which the CD-Rom transfers data from the drive into the system. The speeds range from 1X, 3X, 10X, 50X, 56X, etc. Fig 2.1g shows a typical diagram of a CD-Rom drive.

H. KEYBOARD AND MOUSEThe keyboard and mouse are input devices found in computer hardware. The keyboard is a flat patterned device made up of keys as shown in Fig 2.1h (i) below and Fig 2.1h (ii) shows that of the mouse. The mouse could also be called a pointing device used in providing input into the system.

EMBED PBrush µ § EMBED PBrush µ §

I. MONITORThe monitor otherwise called the VDU (Visual Display Unit) is an output device used in viewing the processes going on within a computer. The monitor has a lot of similarities with the conventional televisions sets we have in our homes. The monitor comes in different types and sizes. Its size is with respect to the quantity of picture it could display. Such as VGA, SVGA, LCD’s, etc. The size is with respect to its viewable area, such as 14”, 17”, and 21” monitors. Fig: 2.1i: CRT MonitorsJ. CASING

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The casing is the external part of the computer that houses all the various components listed above. This device is usually made of a thin and light material usually, aluminum. The casing comes in different sizes and types. Its sizes range from the min-tower, to the high-tower. The types ranges from the two power modes the motherboards come in; such types are AT and ATX casing. Fig 2.1j below shows a typical diagram of a systems casing.

EMBED PBrush µ §Fig 2.1: A complete Desktop System

PRE-INSTALLATION GUIDELINESAlthough undertaking PC installation/assembly does not require a great many manual

skill and technical know-how, some basic facts, nevertheless, have to be fully grasped. Paramount among these is the fact that the PC system consists of several individual electrically sensitive components which work in synergy to impact an optimal system throughput. Hence handling these components (be it software or hardware) entails some extra care. Sticking to some basic rules as regards component handling can eliminate costly errors. The following comprises some of these basic rules, which I had learnt from my S.I.W.E.S. programme.

Prepare the environment: Since virtually all the components of the PC are sensitive devices, much consideration should be given to the state of the environment or surroundings within which an installation is done. This was among the very first things I was taught during my Industrial Training. A suitable floor finish of a workshop for PC installation should be of hard carpet or terrazzo: A rugged floor is strictly to be avoided, as it is dust-prone. Food, liquids or cigarettes must be strictly forbidden from the area. Finally such a place must be well lit.Ensure Safeguards against Electrostatic Discharge (ESD): Some of our every day activities do often times lead to the accumulation of electrostatic charges around our bodies. These charges are not visibly or readily felt if they are below the range of 3000 volts. However the sensitive components of the PC system can become destroyed or damaged just by an electrostatic charge as low as 250 volts! Some ESD events can cause minor or cumulative damages to the affected system device thus rendering such devices inoperable either instantly or in the long run. To prevent ESD events or their associated damages, the following simple safety procedures are adopted:Safely ground yourself before working on the PC.Use static dissipative or static shield material to store computer parts.The use of an antistatic mat (beneath the computer assembly) or an antistatic wristband or both is highly recommended (refer to Fig 4.1). Touching the mat first, before handling the PC or its components, can discharge one of electrostatic charges.

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Consult the component’s installation manual: I found out in my I.T. that working with PC components on presumptions can lead to errors. In other words, one has to read over the installation manual for a particular component before working on it. This is done because some manufacturers may have a different configuration scheme for their devices and these may differ from one’s previous knowledge concerning the configuration/installation of that device.Never use Force: By default, the sockets/slots found on the PC system are pre-designed to accept only the correct type of connectors and in only one direction (to prevent reversal of polarity). Hence, normally, a device will fit into its appropriate socket/slot without being forced in. Therefore when a particular device refuses to be connected easily, it could be a sure sign that a connection is being forced into a wrong end.Turn everything off and disconnect from mains before continuingUse the correct screws and tools: Unfortunately, not all the screws in the PC are standardized. Some screws differ in thread pitch and as such forcing them into the wrong holes can cause damage to the holes thread or even the device. Extra care is needed here; a longer screw forced into a shorter hole can penetrate too far into the device’s housing hence damaging it. The use of the right tools is also important to avoid damaging parts of the components.Maintain a log of all the work: The importance of this particular rule can never be over-estimated. Making a record of the initial settings or layout of PC components before working with/on them will go a long way in ensuring proper connection/reconnection at the end of the other computers in a network, it must be connected to a remote computer called the Print server. The print server supplies the print drivers and settings, which controls the printer and enables the printer to be shared by other users of the network Installing a network printer is almost similar to installing a local printer. The following steps are required in order to install a network printer:Double click on Network Neighborhood or Network Places (Windows 2000, XP) icon on the desktop. Double click on the particular workgroup to open it.Also double click on the particular remote computer’s network name to open it.Right click on the remote unit’s printer name and click on the Install option.Follow the wizard as it guides you through the rest of the process.Alternatively, network printer installation may also be achieved through the following steps:Open Printers and Faxes.Under Printer tasks, click “Add Printer” to open the Add printer wizard and then click next.Click on the “A Network printer or a printer connected to another computer” option and click next to continue.Specify the method of connecting to the desired printer from one of the following displayed options:

Browse for a printerConnect to this PrinterConnect to a Printer on the Internet or a Home or Office Network.Follow the wizard to complete the installation.

In step 4 above, the 1st option comes handy when the name or location of the printer is not known. The 2nd option is used when name and location of the printer on the network is known and it has to be specified in the text box below this option. The 3rd option is used when one wants to connect to a printer across the Internet. The URL to the printer must also be specified.

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PREVENTIVE MAINTENANCE PROCEDURESPreventive Maintenance entails those PC maintenance activities that are routinely carried out in order to prevent the breakdown of the PC system. Preventive maintenance includes activities that ensures a conducive operating environment for the computer system, conditions power-line; protect the system from static electricity (ESD) and electromagnetic inference (EMD), etc.

CLEANINGCleaning is a major part of keeping the system healthy. Cleaning is basically carried out to prevent dust build-up. Overtime, dust builds up on everything it can gain access to. Many computer components generate static electricity that attracts dust particles. In most electronic components, dust forms an insulating blanket which traps heat next to active devices thus causing them to overheat thus resulting to aging of components and eventual failure. Smoke is also another dangerous cousin to dust in PC systems. Besides contributing to heat build-up, smoke residue is particularly destructive to moving parts such as floppy disks, fan motors and so on. Dust build-up can overcome by routinely cleaning the motherboard with a soft brush. A static-free vacuum can be used to remove dust from inside cases and keyboards. Dust covers are also helpful in holding down dust problems. 2.5.2 IDEAL PC WORKING ENVIRONMENT

A lot of environmental factors greatly contribute to the efficient operation of the computer. Besides routine cleaning to eliminate the build-up of dust particles, other environmental conditions like operating temperature; ventilation (air-flow around the computer) and humidity have to be considered.

CONTROLLING HEAT BUILD-UPProper ventilation is needed to allow for good flow of air around a PC system. Computers are ideally designed to operate at room temperature. If ambient temperature rises above 85o F then heat build-up can become a problem. Heat is generated by the electronic components on the system board as they operate.Hot air has to be ejected from the system unit while cool air has to be blown in to ensure that the components do not overheat. To ensure proper air flow around computers the following measures may be employed:

Computers should not be clustered together. They should be well spaced to allow for airflow.Ensure that the power supply fans are working and that cables will not fall into the fans to prevent them from turning when the case is closed.Ensure that the vents of computer case are clear of any material that may block airflow.Routinely, anti-static vacuum or compressed air should be used to blow dust off the motherboard and CPU heat sink. A soft brush may also be used for this.Fans and/or air-conditioners should be installed to ensure proper airflow.It is a good practice to ensure that expansion all expansion slot covers are in place and the outer cover is secured firmly to the machine. If these items are out of place it could disrupt the designed airflow characteristics of the case.

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2.5.3 ELECTROSTATIC DISCHARGE (ESD)Electrostatic Discharge (ESD) commonly known as static electricity is an electrical charge at rest. Static charges easily builds up on the surface of an ungrounded conductor and on nonconductive surfaces. The human body can build up static charges in the range of 25,000V and these build-ups can very rapidly discharge into an electrically grounded body or device. When two objects with dissimilar charges touch, static electricity passes between them until the dissimilar charges become equal. Although ESD won’t hurt humans, it will destroy certain electronic devices. Placing a 25,000V volt surge on an electronic device potentially damages it. Electronic logic devices constructed from Complementary Metal Oxide Semiconductor (CMOS) materials are particularly susceptible to ESD. ESD can cause two types of damage to electronic components: catastrophic failure and upset failure. Catastrophic failure damages the component beyond use while upset failure damages the component so that it does not perform well, although it may still be function to some degree. To protect the computer from ESD, the PC technician must always be grounded of any static charges before touching electronic components including hard drives, motherboards, expansion cards, processors and memory modules. It is compulsory for PC technicians to ground themselves and the computer system before touching any electronic components. The most traditional method of grounding oneself is simply touching an exposed part of the chassis or the power supply unit. The disadvantage here is that this action has to be repeated continuously since the PC technician can easily picks up static charges if he touches any other charged object (including humans) while working on the computer. The rule of the thumb here is that if the PC technician employs this method of grounding, he must avoid touching other potential static charge carriers and must continuously be discharging while working on the computer. Other methods of grounding include the following:Ground Bracelet or Static Strap: is worn around the wrist. One end attaches to the ground conductor such as the computer case or a ground mat or plugs into a wall socket (with only the ground pong making the connection). The bracelet also contains a resistor that prevents electricity from harming the technician. These straps release any static present in the technician’s body and pass it harmlessly to ground. Static strap must never be worn when working on high voltage equipments like monitors and power supply units. It is also not a safe practice to wrap a copper wire around the wrist or ankle and connect it to the ground side of an outlet, such that it substitute a real static strap. The resistive feature of a true static strap is absent. Ground Mats: Ground mats are usually made of rubber or other antistatic material and they provide a grounded surface on which to work. They are particularly helpful in carpeted areas because carpeting is a major source of ESD build-up. Some ground mats are equipped with ground connections that should be connected to the safety ground of a wall socket. Static Shielding Bags: New components come shipped in static shielding bags. These bags should be kept and used to store other devices that are not currently installed in the system. While working on the PC, components may also be laid in these bags.

2.5.4 ELECTROMAGNETIC INTERFERENCE (EMIday. Further, during experimentation with different system settings, this rule will help the system engineer to recall the different combinations tried alongside their respective results.Test everything before assembling: Finally, before reconnecting the system or the associated components it is always good practice to double-check each connection. This ensures that

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nothing is forgotten. Questions like “Are the cables correctly attached?”, “Are there any remaining screws?” are things one should ask oneself.

COMPUTER INSTALLATIONComputer installation entails the assemblage of the essential components that make up a basic computer system. These components, which were discussed in detail in the previous section, could either be field replaceable or non-replaceable.

FIELD REPLACEABLE UNITSField Replaceable modules are those modules that can be easily replaced in the field. Most of the components in the microcomputer system are field replaceable. The field replaceable modules in a typical microcomputer system include the following:System Boards (motherboards)Power SupplyStorage Devices Input/Output DevicesExpansion cardsOn the motherboard, there are also a number of devices that are field replaceable. Such devices are replaced for one of two reasons: replacing a failed unit or upgrading a functioning unit. The field replaceable units on the motherboard include the following:CPUROM BIOS ChipsRAM RAM cacheCMOS BatteryBefore taking a detailed look into the installation steps for these listed FRU’s, let us consider the tools required by every PC technician in order to assemble a microcomputer system.

THE PC TECHNICIAN’S TOOLKITThe PC Technician tool kit consist of a number of hand tools used for assembling, troubleshooting and repairing PC’s. The following list includes the tools and equipments recommended for a well prepared PC technician tool kit:Assorted Flat Blade Screw DriversAssorted Philips Screw DriversAssorted Nut DriversAssorted small torx bit driversNeedle-nose pliersDiagonal pliers Fig 2.1.2: PC Technician’s ToolkitContact CleanersFoam SwabsTweezersMagnifying GlassClip LeadsIC ExtractorMultimeter and Leads

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Fig 2.1.2b From Left-to-right: long nose pliers, small standard flat-head screwdriver, tweezers, medium standard screwdriver and hex wrench

IC Extractors or Pullers were used extensively for removing socket-mounted IC’s. With the extinction of socket mounted chips, in present day microcomputer systems, IC pullers may not find much application except in such task as the replacement of CMOS battery. Multimeters are one of the most basic pieces of electronic equipments used in isolating problems during PC diagnosis. Depending on the dial or function setting, they can be used either as an ammeter or a voltmeter or can measure resistance or continuity (the presence of a complete circuit with no resistance to current). In computer diagnosis and troubleshooting, 99% of the tests made are fully voltage readings. These measurements of ten involve checking the DC side of the power supply unit. Voltage across system board capacitors may also be measured to ascertain whether the board is receiving power. The expected voltage reading for on-board capacitors is 5V. DC voltage readings expected from a PC system using AT power supply are: 5V, -5V, 12V, and -12V. For an ATX power supply, a +3.3V and –3.3V DC voltage reading is also included.

OPENING UP THE PC CASEThe PC casing can come in various designs but generally we have three basic designs in existence. These basic designs are adopted regardless of whether one uses a desktop, mini-tower or full tower system casing. These three basic designs are identified by the manner in which the cases are opened and include:The Case is hinged chassis.The Front cover is attached to the chassis: top moves back and/or up.The Front cover is attached to case (independent of chassis); top and cover pulls forward. Generally, the screws are attached at the back of the casing. Most cases come with the accessories necessary for mounting and attaching the other components. It is advised to use a tower casing as it provides better space and layout for installing devices and also better ventilation features than the desktop case. It is equally good practice to detach the power supply unit (PSU) temporally from the casing: This allows easier access into areas of the casing when components like the motherboard or the HDD IDE cables are to be installed.

INSTALLING DRIVESDrives basically make up the internal storage devices. They represent the microcomputer’s secondary storage. They are typically mounted on the system unit’s drive bay and derive their power from the system unit’s power supply. External storage devices connect to the system unit through options adapter cards installed on the system board’s expansion slot and they employ separate external power supply circuits. Most internal storage devices come in traditional disk drive form factors. So the hardware installation procedure for most internal storage devices (Floppy, hard disk and CD-ROM drives) is the same. Installation of drives is one of the basic installation steps in assembling a PC system. During PC assembly, care should be taken when installing drives to prevent them from falling onto the board, thus damaging it for good. It is sometimes advised to install drives before mounting motherboards, so as to eliminate this possibility. Based on the drive interface technology, two drive types are most

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commonly used in modern day PC system. They are the Integrated Drive Electronics Interface (IDE) drive and the Small Computer System Interface (SCSI) drive.

IDE AND SCSI DRIVESThe Integrated Drive Electronics (IDE) Interface also called AT attachment (ATA) Interface is a system level interface that places most of the controller electronics on the drive unit. Data travels in parallel between the computer and the drive unit with the controller circuitry handling the parallel-to-serial and serial-to-parallel conversions thus allowing the drive unit to be independent of the host computer design. IDE Interface drives also store their formatting information in itself. Such information is placed in it by the manufacturer, and it is used by the controller for alignment and sector sizing of the drive. Updated IDE specifications have been developed to allow more than two drives to exist on the same interface. This specification, which is called Enhanced IDE (EIDE) or ATA-2, also provides improved IDE drivers known as AT Attachment Packet Interface (ATPI), for use with CD-ROM. This implies that the Hard Disk Drive (HDD) and CD-ROM drive could now be connected to board with the same interface. Small Computer System (SCSI) Interface like the IDE interface is a true system level interface. Here however, nearly all the drive’s electronics are placed on the peripheral device such that the duties of the SCSI host adapter are reduced to just physical connections functions, along with some signal compatibility handling. With this arrangement, data arrives at the system interface in a form that is already usable by the host adapter. SCSI drives are used mostly with portable systems. In standard PC system SCSI interface uses a 50-pin signal cable arrangement.

INSTALLING FLOPPY DISK DRIVE (FDD)Floppy Disk Drive installation follows almost the same procedure described for HDD and CD-ROM drive. In floppy disk drive installation, however, no master/slave setting is required. The PC compatible FDD unit uses a 43-pin signal cable designed to accommodate two FDD units. If the installed FDD unit is the only FDD in the system or designed to operate as drive A:, it is connected to the connector at the end of the cable. If it is being installed as Drive B:, then it is connected to the connector toward the center of the cable. The hardware installation step for a FDD unit is as follows:Slide the FDD unit into an open drive bay and install two screws to secure it to the bay.Connect the signal and power cords.Connect the other end of the signal cable to the motherboard connector labeled FDD 1.As with CD-ROM drives, there is also no need to install software drivers for it because modern versions of Windows contain drivers for the basic input/output devices. When the hardware installation of a FDD unit has been completed in a Windows XP based system for instance, the FDD unit is automatically detected and installed (the drivers loaded) when Windows is started. Running POST on the motherboard before installing it on the system case prevents the stress of disassembling all the

INSTALLING HARD DISK DRIVES (HDD)Hard Disk Drive represents the system mass storage device. The HDD hardware installation process is similar to that of other storage devices. However, the configuration and preparation of a HDD is more involving. It is necessary to confirm the master/slave setting for an IDE

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drive or the ID configuration for an SCSI drive before installing it. The hardware installation for an Hard Disk Drive includes the following steps:Disconnect the system’s power cord from the back of the system unitOpen the system unit and slide the drive into one of the system unit’s open drive bay. Install two screws to secure the drive firmly to the bay.Connect the signal and power cords to the drive.

For an IDE HDD, the connector that connects to the board connects to the on-board connector labeled IDE 1. An IDE signal cable can support two IDE drives, it thus have two connectors (one about half-way along the length of the cable and the other on the end of the cable) for connecting to the IDE devices. For a single HDD system, one of the connectors is connected to the HDD while the connector may be connected to a CD-ROM drive. SCSI drives are mostly used in portable systems.After completing the hardware installation process, the drive will need to be configured and formatted. The CMOS setup utility holds the configuration settings of all installed Input/Output devices and it must be set correctly for the type of drive that has been installed. Newer BIOS versions support automatic detection capabilities that allow them to find the drives in the system. If BIOS does not support automatic detection, however, it will be necessary to move into CMOS configuration setup utility and identify the type of drive being installed. In most of the HDD installation process that we encountered during my industrial training, we used auto detection to detect the installed the HDD.

. Fig 2.3.4: The Floppy and Hard Drive installed in the casing & an IDE HDD.

INSTALLING CD-ROM DRIVESThe installation procedure for a CD-ROM drive is a lot similar to that of a HDD. The first thing to do is check the master/slave setting or SCSI ID configuration setting. The hardware installation steps for IDE CD-ROM drive are as follows:Fix the CD-ROM drive onto one of the open drive bays and install two screws on its side to secure it firmly to the bay. Connect the IDE signal cable connector to the CD-ROM Connect the power cableConnect the audio cableIf the CD-ROM drive interface is not the same as the HDD (as is not always the case), it will be necessary to install a controller card in the expansion slot. In step 2 above, if the system is a single HDD system, the CD-ROM is set up as slave drive on the primary interface. In a two HDD system, however, the CD-ROM is set up as master or single drive on the secondary interface. After CD-ROM hardware installation has been completed, it may be necessary to install the software drivers. With modern versions of Windows OS, this however is not necessary, since the hardware device is automatically detected and the required drivers installed for it.

2.3.5 INSTALLING THE MOTHERBOARDBefore installing the motherboard, it is proper to run a Power-On Self Test (POST) on the motherboard while it has not yet been screwed to the chassis to ensure that it is OK. Refer to

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the included motherboard manual and ensure that the CMOS jumper pins are on the “normal” setting (if the setting is otherwise, the motherboard will surely fail to “come on”). Further, temporally connect the PSU to the motherboard and the monitor to its port on the motherboard. The system is then powered by using a screw driver to make a connection between the hot and the ground pins of the DIP switch on the motherboard that connects to the external power switch so as to ascertain that the system passes the POST (Power On Self Test) routines and displays error-free messages on the monitor: This was how I was taught in my I.T. and it is a quick way of detecting a faulty motherboard, CPU or memory in the early installation stages instead of disassembling components later after when the installations may have been completed. If all goes well, disconnect the PSU from the motherboard, align and install the motherboard in the casing using the ports/connector outlets on the back of the casing as guides. Fig 2.3.4(i) shows a labelled picture of the motherboard and Fig 2.3.4(ii) shows the procedure for its installation. Fig 2.3.4(i): A typical Pentium III motherboard with labels of its components.

ADAPTER CARDSAdapter Cards plug into expansion slots in the computer main board and they typically contain the interfacing and controller circuitry for peripherals. In some cases, the entire peripheral may be included on the adapter card. Adapter cards basically enable peripheral devices to communicate with the system thus allowing a wide variety of peripheral devices to be added to the basic system to modify its particular application. As already stated, expansion cards plug into expansion slots on the motherboard. So the adapter card must be compatible with the expansion slot type in which it is to be connected. In Pentium systems, the prevalent expansion slots are often a mix of PCI and ISA buses.

Fig. 2.3.5: From left to right – sample of an internal modem card, network card & PCI expansion slots

PCI VS. ISA EXPANSION SLOTSSystem expansion slots provide connecting point for most of its input/output devices through adapter cards, which communicate with the system through the microprocessor buses in these slots. The Industry Standard Architecture (ISA) expansion slot is a 16-bit expansion slot that was introduced with the IBM-PC AT. ISA is about the most common expansion slot used with microcomputers. Compared with the 8-bit PC XT bus, the 16-bit data bus structure improved the performance of the system by allowing twice as much data to pass through the slot at a time thus making data transfers with 16-bit microprocessors a single step operation.

With the introduction of 32-bit microprocessors the limitations of the 16-bit ISA bus became noticeable. A number of 32-bit expansion slots were developed to support 32-bit microprocessors. Among these were the Extended ISA, Micro channel Architecture and the Peripheral Component Interconnect (PCI). Of these, the PCI slots are most popular with present day Pentium boards. The PCI bus is a low-cost, high performance board that supports automatic configuration of installed expansion cards. The PCI bus supports 32-bit data and 64-bit data transfers at speeds of 132mbps and 264mbps respectively. In standard microcomputer systems, PCI bus normally coexists with ISA bus.

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INSTALLING PCI ETHERNET LAN CARDEthernet LAN card (also called Network Interface Card) is an adapter card that is required by all computers connected in a LAN. LAN Adapter Cards must have connectors that are compatible with the type of cabling being used. Most LAN adapter cards have both RJ-45 connectors and BNC connector such that they can support any type of Ethernet configuration being used.Installing Ethernet LAN card could really be a lot involving. The hardware installation procedure for a PCI LAN card is as follows:Disconnect the system power cord remove the system unit’s cover.Remove the system unit’s back plate and slide the LAN card into one of the empty PCI expansion slots.Secure the LAN card firmly to the system unit by holding it in place with screws.After the hardware installation steps as described above, there may be need to load the device drivers for LAN card. Windows XP will automatically detect and install the drivers for an installed LAN card wpply provides a +3.3V level to the system board (for low voltage microprocessor). In ATX design, the power supply unit pulls in air through the rear of the system unit and blows it on the system board thus cooling the processor directly. With ATX power supplies, there might not be need to add additional fans and heat sinks because the power supply has a side vent in just the right position to blow air on the processor and expansion cards. Another important feature of ATX power supply is the soft switch or soft power feature. With this feature, an OS such as Windows 98 or Windows 2000/XP can turn off the power to the system after the shutdown is done.

2.3.8.2 INSTALLING POWER SUPPLY UNITSInstallation of power supply unit is an activity that is mostly performed when a faulty power supply unit is being replaced with a new one. This is basically as a result of the fact that power supply units are sold together with the system unit cases.CAUTION: All power supplies contain various capacitors inside of them that retain power even after the power supply had all power turned off. Never open up or insert any metal objects into the vents of the power supply as you can risk electrical shock. To start with installing a power supply, it is necessary to open up the case. The method for opening the case will vary depending upon its design. Most new cases use either a panel or door while older systems require the whole cover be removed. Be sure to remove any screws fastening the cover to the case and set them aside. Align the new PSU into place in the case so that the 4 mounting holes align properly. Make sure that any air intake fan on the power supply that resides in the case is facing towards the center of the case and not towards the case cover. Now comes one of the most difficult portions of the power supply installation. The power supply needs to be held in place while it is fastened to the case with screws. If the case has a shelf ledge that the power supply sits on, it will be easier to balance. Make sure that the voltage switch on the back of the power supply is set to the proper voltage level for your country. North America and Japan use 110/115v, while Europe and many other countries use 220/230v. In most cases the switch will come preset to the voltage settings for your region. If the computer already has the motherboard installed into it, the power leads from the power supply need to be plugged in. Most modern motherboard use the large ATX power connector that gets plugged into the socket on the motherboard. Some motherboards require an additional amount of power through a 4-pin ATX12V connector. Plug this in if required.

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There are a number of items residing within a computer case that requires power from the power supply. The most common device is the various hard drives and CD/DVD drives. Typically these use the 4-pin Molex style connector. Locate the appropriate sized power leads and plug them into any devices that require power. At this point all of the installation and wiring should be completed with the power supply. Replace the computer cover or panel to the case. Fasten the cover or panel with the screws that were previously removed to open the case. Now all that is left is to provide the power to the computer. Plug in the AC cord to the power supply and turn the switch on the power supply to the ON position. The computer system should have available power and can be powered on. If you are replacing an older or damaged power supply, the steps to remove the power supply are identical to installing them but in the reverse order.

PRINTER INSTALLATION/TROUBLESHOOTINGA printer is a hardware device used for producing hard copies of documents, pictures, etc. Based on the number of users, a printer may be classified into as either local or shared (network) printer. Local printers are accessible to and used a stand-alone system. It is not shared by a number of users. Network printers on the other hand are used in a Local Area Network (LAN). In a LAN where computers are interconnected to share information and resources, a single printer can be shared by a number of computers (hosts) on the network. Besides printer sharing in a LAN, drives can also be shared. Shared drives also called network drives are accessible to all host computers in the LAN. The use of network printers in the PPMC Warri Area Office is applicable to the Audit and Finance and Accounts departments.Generally, printers may also be classified based on the print method. Other classification criteria include printer speed, quality of characters they produce and how they form characters. Looking at printer classification based on print method, we consider two types: Impact and Non-Impact Printers. Impact printers places an image on a page by making a hammer device to strike an ink ribbon which in turn strikes the paper. An impact printer thus produces characters by causing the print mechanism or its ink ribbon to impact the paper. The characters produced by an impact printer may be fully formed or dot matrix character. Examples of impact printers include:In Non-Impact printers, the print mechanism does not directly impact the paper in order to form characters on the paper. The Laser printer is the major non-impact printer that is used in the Warri Area office of the PPMC. A laser printer utilizes the electro-photographic method of image transfer. Light dots are transferred to a photosensitive rotating drum, which picks up electro statically charged toner before transferring on the paper. The photosensitive drum is coated with a photosensitive plastic, which is given a negative charge over its surface. The modulated laser beam creates positively charged spots (representing the image of the object to

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be printed) on the rotating drum. The negatively charged toner material is attracted to the positively charged written areas (spots) on the drum. Paper is fed past the rotating drum and the toner is transferred to the paper. A pair of compression rollers and a high temperature lamp fuses the toner to the paper. Thus the image written on the drum by the laser is transferred to the paper.A wide range of laser printers used in the Warri Area Office of the PPMC are mostly Hewlett Packad (HP) products and they include the following:HP 1000HP 1100HP 1150HP 1005Laser jet 5N

Fig 2.1.11: Laser Printer

2.4.1 INSTALLING LOCAL PRINTERSRecent versions of Windows have the ability to automatically detect and install a wide range of printers. The system (Operating system) automatically detects and installs the printer as the system boots. But a number of printers still have to be installed directly by the user before they can be available for use. Printer installation is done with the installation CD that comes along with the pack of a new printer. The following steps should be followed when installing a printer.Unpack the printer; properly connect it to power supply and the system unit. Data transfer between the computer and the printer may be through a parallel port or a USB port.Insert the installation CD into the CD ROM drive of the system unit.Click on Start button, highlight and click on Printers and Faxes (if it is on Start menu options as obtainable in Windows XP), else click on Control Panel to open the Control panel window and then double click on Printers and Faxes.Double click on the “Add printer” icon to start the Add printer wizard. Click the Next button.Click the “Local Printer” option and ensure that the “Automatically Detect My Printer” checkbox is cleared.Select the printer port (usually LPT1if the printer uses a parallel port connection) and click the Next button.Select the Manufacturer and Printer Model accurately on the next step and click the Next button. If the installation CD is already in the drive then click “Have Disk”.Set the Printer Name and Printer Sharing options in the next 2 steps.You may decide to print a test page on the next step. Click finish to complete the “Add Printer” process.

2.4.2 INSTALLING NETWORK PRINTERSA network printer is one of the shared resources in a LAN. For a printer to be shared byia and only one node can broadcast messages at a time. In actual implementation, the most common bus network is the Ethernet in which the coaxial cable forms the transmission media.

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Fig 4.4(a): Bus Network Topologies

MERITS OF THE BUS TOPOLOGYThey are easy to install since they conform well to office layoutsSince each node is connected to one main communications line, the network can continue to function normally even when one of the nodes malfunctions or goes down.DEMERITS OF THE BUS TOPOLOGYA break in the main communication or trunk cable will disable the entire networkData transmission is slow since only one node can broadcast messages within a particular time frame.Star Network TopologyA star network connects many computers and computer resources, such as a printer, to a central computer called a server, which directs the flow of information. In this scheme, workstations are attached to a hub and signals are either broadcast to all stations or passed from station to station. If a server scheme is adopted then messages pass directly from a node to the central computer, which handles any further routing (as to another node) that might be necessary. Fig 4.4(b) depicts this scenario.

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Fig 4.4(b): Star Network TopologiesMERITS OF THE STAR NETWORK TOPOLOGYThey are easy to install since they conform well to office layoutsA break in the communication cable linking one workstation to the central computer only affects the attached computer.DEMERITS OF THE STAR NETWORK TOPOLOGYA failure in the central computer results in a shutdown of the entire network.Cabling costs of this type of topology is high since each node is individually wired to the hub.Token Ring Network TopologyA token ring network uses a special message called a token that travels from computer to computer. The token designates which computer sends information through the network. On a token ring network, a token governing the right to transmit is passed from one station to the next in a physical circle. If a station has information to transmit, it “seizes” the token, marks it as being in use, and inserts the information. The “busy” token, plus message, is then passed around the circle, copied when it arrives at its destination, and eventually returned to the sender. The sender removes the attached message and then passes the freed token to the next station in line. Fig 4.5(c) illustrates this process. Fig 4.4(c): Token Ring Network TopologyMERITS OF THE TOKEN RING NETWORK TOPOLOGYWorkstations on this topology type do not have to compete for access to the network.Network collisions are reduced in the token ring network topology.DEMERITS OF THE TOKEN RING NETWORK TOPOLOGYA break in one node in the ring network causes a data transmission backup routing. This imposes additional overhead in time for the network.Cabling costs of this type of topology is also high since it adopts the cabling scheme of the star network topology.

4.5 BASIC NETWORK TOPOLOGIES FOR WANS & ENTERPRISE NETWORKS

HYBRID NETWORKS: - Enterprise networks and wide area networks expand on the basic network topologies as listed for the LAN. This expansion on the basics led to the design and implementation of hybrid networks; Hybrid networks are merely network topologies formed as a result of the combination of certain desirable features from the existing basic topologies. The four most commonly adopted hybrid network topologies include:

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Ring Backbone Network TopologySwitched Core Backbone Network TopologyMesh Network TopologyInterlinked Star Network Topology

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4.5.1 Ring Backbone Network TopologyThis is a high-speed network that interconnects many lower speed networks, delivering frames and packets among them.

4.5.2. Switched Core Backbone Network TopologyThis type of topology is usually a switched core. This switched core consists of ATM (Asynchronous Transfer Mode) switch or a mesh of ATM switches that provide virtual circuits among all the interconnected networks. Most service providers and Internet exchanges use this topology.

4.5.3 Mesh Network TopologyThis is a network topology of interconnected routers and/or switches with multiple paths and the ability to route around failed links. The Internet is a good example of this.

4.5.4 Interlinked Star Network TopologyThis is a hierarchical topology that provides redundant links and high-availability for private WANs and service providers networks. Further in this topology, each data centre has links to remote sites but the backup data links may de only. The data centres are interconnected and data is replicated across the link.Finally Fig 4.5(a) and Fig 4.5(b) summarizes these different topologies and ways of interconnecting WANs.

Fig 4.5(a): Hybrid Network Topologies Fig 4.5(b): Enterprise and WAN Topologies (Internet Topology)4.6 COMPUTER NETWORK COMPONENTSObviously, a computer network consists of components working in synergy to impact functionality. Like any other computer-related concept, networking involves the hardware and software. The network components can be grouped into 4 different categories namely: -File Servers and WorkstationsTopology ComponentsNetwork PrintersNetwork SoftwareFile Servers and WorkstationsThese are the real workhorses of the network. They provide the distributed processing, network control, and a platform for network operating systems and applications.

Topology ComponentsThese are the components that provide network connectivity. They are the glue that binds the file servers and workstation (and other shared system accessories) together. The following are devices that enable topology in modern day networks.Network Interface Cards (NIC): - These are the internal adapters that enable communication or connection point between the file server/workstation CPU and the network topology. A NIC

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provides the attachment point for a specific type of cable such as coaxial, fibre optic or twisted pair, and is always designed for a specific type of network. NICs are defined by the physical and data-link specifications i.e. the mechanical and electrical specifications. The mechanical specification define the physical connection methods to the cable while the electrical specification defines the framing methods used to transmit data bit streams across the cable. Fig 4.6(a): A typical 10/100 Dlink Ethernet NIC & 3COMM NICHubs: - These devices provide a control point for signal routing or packet broadcasts. With the hubs, multiple systems within a LAN can be linked up with the central server or among themselves. Fig 4.6(b): From left to right – A 24-port hub and an 8-port hubCabling: - This is the pathway for network communication and forms the actual transmission media through which data is passed. The most popular types of cabling include coaxial, fibre optics, unshielded and shielded twisted pairs. Fig 4.6(c): Common types of physical CablesRouters: - These are internetworking devices that connect similar or heterogeneous (dissimilar) networks. The router is a more intelligent component that can interconnect many different types of computer network. Many large companies have corporate data networks that are founded on a collection of LANs and routers. From the user's point of view, this arrangement provides them with a physically diverse network that looks like one coherent resource.Gateways: - A gateway can be a computer system or other device, which acts as a translator between two systems, or networks that do not use the same communication protocol, data-formatting structures, or architecture.Bridges: - This is a LAN connection device with two or more ports that forwards the frames from one LAN segment to another. The point to note here is that the bridge is the more basic device and can only connect LANs of the same type.

Fig 4.6(d): From left to right – A Bridge-Router-enabled WAN & Gateway-enabled LANsSwitches: - On its part, switches ar)

Electromagnetic interference (EMI) is a system disrupting electromagnetic radiation created by some other electronic device. Such magnetic radiation is produced as a side effect when electricity flows. Data in data cables crossing electromagnetic fields can become corrupted causing crosstalk. Using shielded data cables covered with protective materials could provide considerable protection from cross talk. The following measures could be applied to cut down EMI: PCs can emit EMI to other PCs and as a result PCs should not be clustered together. Face plates should be installed over empty drive bays and slot covers over empty expansion slots.

POWER-LINE PROTECTIONDigital equipments are very sensitive to power variations and losses. Even a very short loss in power can short a computer down resulting in the loss of any current information that has not been saved in mass storage. Typical power supply variations fall into two categories: Transients and Sags. Transients are over-voltage conditions and depending on the period for

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which it lasts could be Spikes (measured in nanoseconds) or Surges (measured in milliseconds). Sags are under-voltage conditions and could be in the form of Voltage sags or Brownouts. Voltage sag typically lasts a few milliseconds while a brownout lasts for a protracted period of time. Brownouts and power failures are easily noticeable because of their duration. Other fast-acting disturbances can cause symptoms that could no be easily traced to power supply. Spikes are particularly dangerous to electronic equipments. Sags may cause the system to reboot because the system thinks the power was actually turned off. A wide range of devices is used to filter the AC input to computers and their peripherals (that is condition the AC input to eliminate highs and lows) and provide back-up power when AC fails. Such devices are grouped into main categories: Surge SuppressorsUninterruptible Power Supplies (UPS)

SURGE SUPPRESSORSSurge suppressors are devices that prevent potentially damaging power surges in an electrical current from reaching a computer or other device. Surge suppressors also called Surge protectors provides a row of power outlets and on/off switches that protect the equipments from over voltages on AC power lines and telephone lines. Surge suppressors work by collecting and diffusing excess power, sometimes within a few billionths of a second. They protect the computer from sudden changes in voltage level such as spikes from lightening strikes. These units passively filter the incoming power signal to smooth out variations. A surge suppressor might be a shunt type that absorbs the surge or a series type that blocks the surge from flowing. The Clamping Voltage is the let-through voltage a shunt type surge suppressor will allow passing through. Surge suppressors are not always reliable. When the fuse inside the surge suppressor blows, it no longer provides protection from power surges but continues to provide power without warning the user.

UNINTERRUPTIBLE POWER SUPPLYUninterruptible Power Supplies (UPS) provides back-up power in the event that AC fails completely. They are battery-based systems that monitor the incoming power and kicks in when unacceptable variations occur in the power source. A common UPS is a rather heavy box that plugs into an AC outlet and provides one or more outlets for the computer and its peripherals. It has an on/off switch, easy to install and requires no maintenance. A UPS is a truly reliable power-line protection device. Unlike surge suppressors, a UPS provides two types of backup systems: a Standby power system and a truly interruptible power system. The Standby system monitors the power in the input line and waits for significant variations (such as spikes or brownouts) to occur. The batteries in this unit are held out of the power loop and draw only enough current from the AC source to stay recharged. When such a variation (interruption) occurs, the UPS senses it and converts the output of the battery to an inverter circuit that converts the DC output of the battery to AC voltage and current that resembles

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commercial AC supply. The uninterruptible power system ensures that the batteries and converters are always actively attached to the output of the UPS, such that when a total blackout occurs no, switching of the output is required and the battery/inverter section just continues under its own power. In this way, a UPS provides efficient protection than other power-conditioning systems. EMBED PBrush µ §Fig 2.2.5: UPSCHAPTER THREE

SOFTWARE ACTIVITIES IN ITUSOFTWARE INSTALLATIONHaving completed the hardware installation, one can then proceed to install the resident software. From my I.T. experience with ITU of PPMC Warri Area Office, the steps for the PC software installation can be summarized as follows:

PREPARING THE HARD DRIVEBefore it can be used, the hard drives have to undergo some preparations, which will ultimately get it ready for the storage and retrieval of data. These steps can be outlined by three routines as follows:Detecting the installed drives from CMOS Setup: Performing an auto-detection using the CMOS Setup program is essentially the first step in HDD preparation. This routine ensures that the system recognizes the installed drives (and their associated parameters) for proper access. It also serves as a kind of preliminary troubleshooting scheme in that a faulty drive can be suspected if CMOS Setup did not detect it. Different motherboards come with their own CMOS Setup so one has to consult the M/B manual on how to use the particular Setup.Partitioning the Hard drive: Partitioning divides the hard disk logically into separate drives or volumes. This is beneficial if one considers installing multiple operating systems and to fully utilize/manage the additional capacity of the hard disk. To partition a HDD, two approaches are adopted: - Partitioning with a special disk utility program provided by the manufacturer (e.g. Seagate’s Disk Manager or Western Digital’s EZ utility).Using the FDISK program obtainable from a Startup floppy disk. This Startup disk is created from a system already loaded with the operating system one intends to install on the new system. The FDISK itself is menu-driven and user-friendly. Therefore it is easier for the user to initiate a desired partitioning scheme by making proper selections from the menu.For a 20 GB hard disk, one can consider a portioning scheme (in terms of disk space allocation) of 50%, 30% and 20% for the primary DOS partition and two extended DOS partition respectively. It is proper to make the primary DOS partition the active partition.Formatting of the Hard disk: - Formatting organizes the disk storage into a collection of “data compartments”, each capable of being located (addressed) by the operating system for systematic data storage and retrieval. The two prominent file structures, which can be created by formatting, are FAT (File Allocation Table) system and NTFS (New Technology File System). The formatting is done by either running the format program from the Start up diskette, using a hard disk utility program (like the Seagate’s Disk Manager) or using a bootable OS CD e.g. a bootable Windows 2000 or Win XP CD.

3.2.2 INSTALLING THE OPERATING SYSTEM (OS)

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Current day operating systems come with fully automated installation/Setup programs and hence are easy to install. However, a careful choice of OS from the available ranges based on one’s computing requirements and needs, will determine the range of other software that can be installed to tap the functionality of the OS. Common procedure for OS installation is to boot-up the system with a Startup floppy, copying the OS installation files from the CD to the host system’s hard drive (the active primary partition) and running the Setup program from the HDD. As I learnt from my I.T., using this approach makes it possible for the OS to access other needed system files from the HDD, whenever a new component is installed, instead of prompting for the OS CD, which might no longer be available again. The operating systems from which ledge is not given to the student either because the industry-based supervisors are impatient or unwilling to pass on the knowledge.Conclusively, the S.I.W.E.S program should continue and government put in more funds to promote the program.

REFERENCE

PPMC Editorials PPMC: A Profile

Charles J. Brooks A+ Certification Training Guide, 2nd Edition

Microsoft Encarta encyclopedia Standard Edition 2005

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6868$&68F68dh 68a$gdã½6868one can choose include Windows 98, Windows 2000, Win XP or even Unix and Linux. Windows XP Professional Edition was the most frequently installed operating system during my SIWES programme with ITU PPMC, Warri. Install the Device Drivers: - A device driveris a software component that permits a computer system to communicate with a device. A printer driver for instance is a device driver that translates computer data into a form understood by the intended printer. In most cases, the driver also manipulates the hardware in order to transmit the data to the device. However, device drivers associated with application packages typically perform only the data translation; these higher-level drivers then rely on lower-level drivers to actually send the data to the device. Device drivers are thus needed for effective communication between the OS and the installed hardware. Components like the sound card, VGA card, modem and network cards require suitable device drivers. The installation can be handled in 2 ways: By Auto-Setup or by manual installation. Auto-Setup involves using the automated device driver Setup program – which will detect installed devices and install the appropriate device drivers for them. This format is recommended for novices in software installation. A qualified person handles the manual installation, where the engineer selects the required and correct drivers. A screenshot of a manual installation routine (for a system running Windows 98) is given in Fig 3.2.2. Fig 3.2.2: Screenshot of the manual installation of a device driver for the network adapter (Win98).

3.2.3 INSTALLING THE APPLICATION SOFTWAREApplication software are the end-user tools for productivity and computing tasks. Operating systems only provide the needed platform for application programs to run. The end users work directly with the application programs which are used to accomplish user specific tasks. It more appropriate to install Anti-Virus software first before other application software. A recommended sequence for installing application software and the types to install can be given as follows: Install an Anti-Virus software (e.g. Norton AntiVirus, PC-Cillin or McCafee Antivirus)Install an office productivity software (e.g. MS OFFICE 2000 or Corel WordPerfect suite)Install the desktop publishing software (e.g. CorelDraw 10)Install the Media content tools/programs (e.g. Windows Media player or PowerDVD)

SOFTWARE MAINTENANCESoftware maintenance refers to those set of activities that are routinely carried out to protect computer from failure. Utility programs incorporated into the operating system carry out Software maintenance. These utility programs are not purely system software but they do perform some system hardware routines, which can be controlled at the user level. Some application programs (e.g. ant virus software) are also used to carry out software maintenance. Software maintenance routines are usually carried out for one of the following reasons:Consolidating fragmented files and folders on your computer's hard disk, so that each occupies a single, contiguous space on the volume. Scan the surface of the hard drive so as to check for errors, which could result from improper shutdown.Providing effective virus protection by monitoring files as they are being accessed and ensuring that infected files are not accessed.

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Restore the computer to a previous state, if a problem occurs, without losing your personal data files (such as Microsoft Word documents, browsing history, drawings, favorites, or e-mail).

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Protecting data from accidental loss if your system experiences hardware or storage media failure.

Software maintenance is a necessary activity that must be carried out routinely in order to ensure a healthy computer system. Software maintenance utilities are incorporated into Windows operating system. Such software utilities could be started directly by the user or by the operating system itself, when a provoking change or event occurs. In Windows 9X for instance, Scandisk is automatically started during a reboot that occurs as a result of improper shut down. Detection of a virus-infected file automatically prompts the user to scan the entire system. Maintenance Software could be grouped into two main categories: Antivirus and Disk management software. Software maintenance utilities that are incorporated into windows could be accessed through Start/Programs/Accessories/System Tools are essentially Disk management software and they include the following:Scan DiskDisk DefragmenterBack UpSystem Restore

ANTIVIRUSAn anti virus software is a program installed to detect and remove computer viruses from the computer system. Computer viruses are programs designed to replicate and spread on their own. They are designed to sneak into the system and could take control of the machine, leaving a humorous message or even destroying data. Computer viruses spread from one computer to another through infected disks or through a computer network. When the virus file becomes active, it basically resides in memory when the computer is running. Computer viruses may be grouped into the following categories:Boot Sector Virus: This virus copies itself onto the boot sector of a floppy or hard disk, replacing the boot sector’s original code with its own code. This allows it to be loaded into memory before anything else.File Infectors: are viruses that add their virus codes to executable files. When the file with the virus is executed, it spreads to other executable files.Trojan Horse: This virus type is a legitimate program that is found on any system. They are more likely to damage files and could even cause physical damage to disks.A number of viruses with different names have been created from these three categories but they all basically cause damage to the computer system. Anti virus programs continuously monitor the system to ensure that an infected file is not accessed. Whenever the file about being accessed contains a virus, the user is immediately promoted and one of the following steps could be taken: Heal the infected file, Quarantine the infected file or Delete the infected file.

DISK MANAGEMENT

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Disk management utilities are designed to carry out house keeping functions on the system’s disk drive(s). As already stated, they are incorporated into the operating system. Let’s take a detailed look at the Windows disk management utilities.

DISK DEFRAGMENTERDisk Defragmenter analyzes local volumes and consolidates fragmented files and folders so that each occupies a single, contiguous space on the volume. As a result, the system can access files and folders and save new ones more efficiently. By consolidating your files and folders, Disk Defragmenter also consolidates a volume's free space, making it less likely that new files will be fragmented. The process of consolidating fragmented files and folders is called defragmentation.The amount of time that defragmentation takes depends on several factors, including the size of the volume, the number and size of files on the volume, the amount of fragmentation, and the available local system resources. It is ideal to first analyze the volume before going on to defragment. Windows prompts the user to either go on to defragment or not depending on the result of the Volume Analysis. Disk Defragmenter can defragment volumes that are formatted with the file allocation table (FAT) file system, the FAT32 file system, and the NTFS file system.

SCAN DISKScan Disk is used to check the system’s drive for lost allocation units and corrupted files that may have been cross linked in FAT. It is basically used to optimize disk storage by locating and removing files that are corrupted. It also makes corrections to file or disk errors as it detects them. Scan Disk is always executed whenever an improper shutdown occurs. When the user starts Scan Disk, the user can select the drive to be examined as well as the type of scan (standard or thorough) and set Scan Disk to automatically fix errors from the Scan Disk main page. Standard test searches files and folders on the disk for errors while thorough test checks the disk physical surface for problems.

SYSTEM RESTORE System Restore is a component of Windows XP Professional that you can use to restore your computer to a previous state, if a problem occurs, without losing your personal data files (such as Microsoft Word documents, browsing history, drawings, favorites, or e-mail). System Restore monitors changes to the system and some application files, and it automatically creates easily identified restore points. These restore points allow you to revert the system to a previous time. They are created daily and at the time of significant system events (such as when an application or driver is installed). You can also create and name your own restore points at any time.

BACK UPThe Backup utility helps you protect data from accidental loss if your system experiences hardware or storage media failure. For example, you can use Backup to create a duplicate copy of the data on your hard disk and then archive the data on another storage device. The backup storage medium can be a logical drive such as your hard drive, or a separate

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storage device such as a removable disk, or an entire library of disks or tapes organized into a media pool and controlled by a robotic changer. If the original data on your hard disk is accidentally erased or overwritten, or becomes inaccessible because of a hard disk malfunction, you can easily restore the data from the archived copy.Backup creates a volume shadow copy of your data to create an accurate point-in-time copy of the contents of your hard drive, including any open files or files that are being used by the system. Users can continue to access the system while the backup utility is running without risking loss of data.Using Backup, you can: Archive selected files and folders on your hard disk. Restore the archived files and folders to your hard disk or any other disk you can access. Use Automated System Recovery to save and restore all the system files and configuration settings needed to recover from a complete system failure. Make a copy of any Remote Storage data and any data stored in mounted drives. Make a copy of your computer's System State, which includes the system files, the registry, Component Services, the Active Directory database, and the Certificate Services database. Make a copy of your computer's system partition, boot partition, and the files needed to start up your system in case of computer or network failure. Schedule regular backups to keep your archived data up-to-date. You can use Backup to back up and restore data on either file allocation table (FAT) or NTFS file system volumes.

CHAPTER FOUR NETWORKING

BASIC NETWORK CONCEPTS

The term network can be used to denote a collection of distributed, intelligent machines which share data and information through interconnected lines of communication. Hence a network is a combination of hardware and software components. We can classify a computer network in three ways - classifications based on size, on connectivity and on topology.

4.1 CLASSIFICATION OF NETWORKS BASED ON SIZEComputer networks can be categorized according to size. The three most popular classifications in this criterion are: -LAN (Local Area Network): - This is a small collection of workstations in a local geographical area. LAN’s typically serve small to medium-sized offices on a single floor. LANs commonly include microcomputers and shared (often expensive) resources such as laser printers and large hard disks. Most (modern) LANs can support a wide variety of computers and other devices. Each device must use the proper physical and data-link

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protocols for the particular LAN, and all devices that want to communicate with each other on the LAN must use the same upper-level communications protocol. Although single LANs are geographically limited (to a department or an office building, for example), separate LANs can be connected to form larger networks.WAN (Wide Area Network): - Basically this is a large collection of LANs. WANs extend the local network over large geographical or technical boundaries. This geographical expansion is achieved through worldwide communication lines and advanced routers or gateways. The technical expansion of WANs is achieved through the integration of dissimilar machines speaking dissimilar languages.MAN (Metropolitan Area Network): - This is a restricted WAN confined to a specific metropolitan area. MANs share a common goal – municipal integration that may include the provision of electronic communications between a variety of different municipal entities like banking, industry, home computers etc. Fig 4.1:From left to right –A LAN within an office building & A WAN of 2 separate firms across the globe

4.2 CLASSIFICATION OF NETWORKS BASED ON CONNECTIVITYConnectivity is the underlying theme of all computer networks. After all, their purpose is to share electronic resources through a collection of interconnected lines. The following is a brief description of these three network connectivity fundamentals.Peer-To-Peer Networks: - These systems are unique in that they share computer resources without the aid of one central file server or network operating system. Peer-to-peer networks rely on the workstations to control network operations. There is no one point of control or failure. Though each workstation has its own OS, the distributed workstations can share hard disks and printers directly with the other workstations.Client/Server Networks: - This is an arrangement used on local area networks that makes use of “distributed intelligence” to treat both the server and the individual workstations as intelligent, programmable devices, thus exploiting the full computing power of each. This is done by splitting the processing of an application between two distinct components: a “front-end” client and a “back-end” server. The client component, itself a complete, stand-alone personal computer (versus the “dumb” terminal found in older architectures such as the time-sharing used on a mainframe) offers the user its full range of power and features for running applications. The server component, which can be another personal computer, minicomputer, or a mainframe, enhances the client component by providing the traditional strengths offered by minicomputers and mainframes in a time-sharing environment: data management, information sharing between clients, and sophisticated network administration and security features. Not only does this increase the processing power available, but it also uses that power more efficiently. The client portion of the application is typically optimised for user interaction, whereas the server portion provides the centralized, multi-user functionality.Interconnectivity: - This approach allows network expandability and involves the extension of network resources beyond the local boundaries of a LAN for example. By interconnectivity, multiple like or unlike LANs are capable of being connected. Some of the components required to achieve interconnectivity include modems, routers, gateways, bridges and switches etc (these will be discussed in the topology section).

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Fig 4.2: Diagram showing network Interconnectivity.

4.3 CLASSIFICATION OF NETWORKS BASED ON TOPOLOGYOwing to the different spreads or sizes of networks, various topologies are adopted in implementing a network scheme. A network topology can thus be defined as the physical layout of a network. In other words, the layout of a network’s cable system and the methods that workstations use to access and transmit data on the cable forms the network topology. In the context of LANs (Local Area Networks) or WANs (wide Area Networks), different topologies can be adopted as follows: -

4.4 BASIC NETWORK TOPOLOGIES FOR LANSThe three most commonly adopted network topologies for LANs include:Bus Network TopologyStar Network TopologyToken Ring Network TopologyBus Network TopologyThe Bus topology consists of a single cable trunk that connects one workstation to the next in a daisy-chain fashion. This can be seen from Fig 4.4(a). In this topology, all the nodes share the same mede multipoint connection devices that provide a point of attachment for a single computer or another device (hub or switch) that has multiple computers attached to it. The most important feature is that any device attached to one port can directly communicate with a device on another port over what is essentially a private link. Network switching removes the network sharing problems – network contentions, collisi

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