Computer Systems - WordPress.com · 1.1 Explain the role of computer systems in different environments 1.2 Explain the hardware, software and peripheral components of computer systems

Computer Systems C_ITCO011 & C_ITCO111

Compiled by Dr Neil Croft

Updated by Marwick Makwindi

Quality assured by Robert Matiwa

Edited by Carine Snyman

Version 1.0

NQF Level 5

Credit value: 12

October 2014 CTI Education Group

TABLE OF CONTENTS

INTRODUCTION .............................................................................................. 1

Summary of learning outcomes and assessment criteria ............................................. 2

UNIT 1: INTRODUCTION TO COMPUTER SYSTEMS ........................................ 11

1.2.1 Principles of operation ............................................................................... 13 1.2.2 Configuration ........................................................................................... 14

1.3.1 System software ....................................................................................... 18 1.3.2 Application software .................................................................................. 19

1.4.1 Form factor .............................................................................................. 21 1.4.2 Bus architecture ....................................................................................... 21 1.4.3 Components ............................................................................................. 22

UNIT 2: SYSTEM COMPONENTS ..................................................................... 27

2.3.1 External ports .......................................................................................... 29 2.3.2 PS/2 ports ............................................................................................... 30 2.3.3 Serial ports .............................................................................................. 30 2.3.4 Parallel ports ............................................................................................ 31 2.3.5 VGA ports ................................................................................................ 31 2.3.6 USB ports ................................................................................................ 32 2.3.7 SCSI ....................................................................................................... 34 2.3.8 IEEE 1394 (Firewire) ................................................................................. 34 2.3.9 High definition multimedia interface (HDMI) and other display ports................ 35

2.4.1 Input devices ........................................................................................... 37 2.4.2 Output devices ......................................................................................... 39

Module aim ................................................................................................................. 1 Module abstract .......................................................................................................... 1 Learning outcomes and assessment criteria ............................................................... 2

Module content ........................................................................................................... 3 Lectures ..................................................................................................................... 5 Class exercises and activities ..................................................................................... 5 Information resources ................................................................................................ 5 Recommended information sources ............................................................................ 6 Using this Study Guide ............................................................................................... 6 Purpose ...................................................................................................................... 7 Structure .................................................................................................................... 7 Individual units .......................................................................................................... 7 Glossary ..................................................................................................................... 8 The use of icons .......................................................................................................... 8 Alignment between Study Guide, learning outcomes and assessment criteria ........... 9 Concluding remarks .................................................................................................. 10

Learning objectives .................................................................................................. 11 Introduction ............................................................................................................. 11 1.1 Computer system basics ................................................................................... 12 1.2 Classification of computer systems................................................................... 13

1.3 Software ........................................................................................................... 17

1.4 Motherboard ..................................................................................................... 20

Concluding remarks .................................................................................................. 26 Self-assessment ....................................................................................................... 26

Learning objectives .................................................................................................. 27 Introduction ............................................................................................................. 27 2.1 Signalling ......................................................................................................... 28 2.2 Data units ......................................................................................................... 28 2.3 Ports ................................................................................................................. 29

2.4 Peripheral devices ............................................................................................ 37

Concluding remarks .................................................................................................. 41 Self-assessment ....................................................................................................... 41

UNIT 3: SYSTEM INSTALLATION ................................................................... 42

3.1.1 Health and safety laws .............................................................................. 43 3.1.2 Electricity ................................................................................................ 44 3.1.3 Cathode ray tube (CRT) safety ................................................................... 46 3.1.4 Electric fire .............................................................................................. 46 3.1.5 Cable management and lighting techniques ................................................. 47 3.1.6 Static electricity and electrostatic discharge (ESD) ........................................ 48

3.2.1 HDDs ...................................................................................................... 50 3.2.2 Solid state drives (SSDs) ........................................................................... 52 3.2.3 HBAs ....................................................................................................... 54 3.2.4 Installing disk drives ................................................................................. 56 3.2.5 RAID ....................................................................................................... 61

3.3.1 Optical disc storage ................................................................................... 63 3.3.2 Installing optical or tape drives ................................................................... 66

3.4.1 Memory types .......................................................................................... 68 3.4.2 Memory components ................................................................................. 73 3.4.3 Installing and upgrading memory ............................................................... 76

3.5.1 Overview of CPU ....................................................................................... 78 3.5.2 CPU architecture ....................................................................................... 80 3.5.3 Other CPU features ................................................................................... 84

3.6.1 Parts of a PC case ..................................................................................... 86 3.6.2 Removing a system case lid ....................................................................... 87

3.7.1 Overview of OS installation ........................................................................ 87 3.7.2 Installation boot methods .......................................................................... 88 3.7.3 Windows setup ......................................................................................... 93 3.7.4 Windows XP setup .................................................................................... 95 3.7.5 Windows Vista and Windows 7 setup ........................................................... 97

UNIT 4: SYSTEM CONFIGURATION .............................................................. 101

4.1.1 BIOS component information ................................................................... 102 4.1.2 BIOS security ......................................................................................... 104

4.2.1 Configuring computers for business use ..................................................... 104 4.2.2 Configuring computers for home use ......................................................... 106

UNIT 5: SYSTEM TESTING ........................................................................... 109

5.1.1 Indicator lights ....................................................................................... 110 5.1.2 Alerts .................................................................................................... 110 5.1.3 Overheating ........................................................................................... 110 5.1.4 Loud noises ............................................................................................ 110 5.1.5 Visible damage ....................................................................................... 111

Learning objectives .................................................................................................. 42 Introduction ............................................................................................................. 43 3.1 Safety procedures ............................................................................................. 43

3.2 Mass storage devices ........................................................................................ 50

3.3 Removable storage ........................................................................................... 63

3.4 System memory ................................................................................................ 68

3.5 CPU ................................................................................................................... 78

3.6 Disassembling a PC........................................................................................... 85

3.7 Installing Windows ........................................................................................... 87

Concluding remarks .................................................................................................. 99 Self-assessment ..................................................................................................... 100

Learning objectives ................................................................................................ 101 Introduction ........................................................................................................... 101 4.1 CMOS Setup .................................................................................................... 102

4.2 Custom configuration ..................................................................................... 104

Concluding remarks ................................................................................................ 107 Self-assessment ..................................................................................................... 108

Learning objectives ................................................................................................ 109 Introduction ........................................................................................................... 109 5.1 Troubleshooting hardware .............................................................................. 110

5.2.1 No power ............................................................................................... 111 5.2.2 Using a multimeter ................................................................................. 112 5.2.3 Using a power supply tester ..................................................................... 114

5.3.1 POST not running ................................................................................... 115 5.3.2 POST errors ........................................................................................... 115 5.3.3 BIOS time and settings reset .................................................................... 116 5.3.4 OS searches ........................................................................................... 117

5.5.1 Unstable operation (system crash or hang) ................................................ 117 5.5.2 Heat ...................................................................................................... 118 5.5.3 CPU not working ..................................................................................... 119 5.5.4 Speed problems ...................................................................................... 119

5.6.1 Lockups ................................................................................................. 119 5.6.2 Windows Memory Diagnostics tool ............................................................ 120 5.6.3 New memory not recognised .................................................................... 121

UNIT 6: SYSTEM MAINTENANCE AND UPGRADE .......................................... 123

6.2.1 Check Disk ............................................................................................. 124 6.2.2 Disk Defragmenter .................................................................................. 126 6.2.3 Disk Cleanup .......................................................................................... 128 6.2.4 Task Scheduler ....................................................................................... 128 6.2.5 Patch management ................................................................................. 130 6.2.6 Update policy ......................................................................................... 131

6.3.1 Backup types ......................................................................................... 137 6.3.2 Restoring data and verifying backups ........................................................ 138 6.3.3 Shadow copies ....................................................................................... 139 6.3.4 Restoring user profiles ............................................................................. 140

6.4.1 Malware types ........................................................................................ 143 6.4.2 Malware symptoms ................................................................................. 146 6.4.3 Virus alert hoaxes ................................................................................... 147 6.4.4 Preventing malware infection ................................................................... 148

GLOSSARY................................................................................................... 156 BIBLIOGRAPHY ........................................................................................... 157

5.2 Troubleshooting power problems ................................................................... 111

5.3 Troubleshooting POST .................................................................................... 114

5.4 Troubleshooting the motherboard .................................................................. 117 5.5 Troubleshooting the CPU ................................................................................ 117

5.6 Troubleshooting memory ................................................................................ 119

5.7 Troubleshooting adapter cards and I/O ports ................................................ 121 Concluding remarks ................................................................................................ 122 Self-assessment ..................................................................................................... 122

Learning objectives ................................................................................................ 123 Introduction ........................................................................................................... 123 6.1 Maintaining and optimising disk drives ........................................................... 124 6.2 Utility software ............................................................................................... 124

6.3 Data backup ................................................................................................... 135

6.4 Computer malware ......................................................................................... 143

Concluding remarks ................................................................................................ 155 Self-assessment ..................................................................................................... 155

Introduction Page 1

© CTI Education Group

Introduction Welcome to Computer Systems! In this module, we will develop your

understanding of computer systems by means of a variety of learning methods, including lectures, discussions, case studies and presentations. We

will explore software, hardware, networking, memory management, storage, interfacing and various other related technologies, all of which will develop

your understanding of the subject field and support your knowledge and skills

base.

The main source of information for Computer Systems is this Study Guide.

In this introductory unit, we provide you with the following information on Computer Systems:

A brief description of the aim of the module

An abstract of the module The learning outcomes and assessment criteria involved in the module

An outline of the module content An outline of the module structure

An explanation of the purpose, design and proper use of the Study Guide

Module aim The aim of this module is to enable you to understand computer systems and

apply your theoretical knowledge to practical applications when building, configuring and maintaining computer systems.

Module abstract

Most information technology (IT) professionals will, at some stage, have to set up, use, customise and maintain computer systems. In order to do so

effectively, they will need to understand how computer systems work. You will develop an understanding of the theoretical aspects of computer systems and

how information is processed. This module will explore the hardware, software and peripheral components that make up such a system.

There are many different manufacturers of computer systems and each will

produce a wide range of models with different specifications. Deciding which

particular model is appropriate for a given situation depends on a variety of factors. Custom-built computer systems are an advantage when meeting

specialised requirements while maintaining performance and keeping costs low. These aspects will be explored in this module so that you can make

informed choices when designing a computer system for a given purpose.

Introduction Page 2


You will also be able to apply your theoretical knowledge to practical application by building, configuring and testing a functional computer system,

which will need to meet a given specification.

Computer users, further, need the skills required to set up and perform routine maintenance on computer systems. Although this module does not extensively

cover fault finding and repair, it does include the basic maintenance skills that would, normally, be expected of most computer users.

Learning outcomes and assessment criteria

On successful completion of this module, you will:

1. Understand the functions of computer systems

2. Be able to design computer systems

3. Be able to build and configure computer systems

4. Be able to undertake routine maintenance on computer systems

The following table outlines the assessment criteria that are aligned to the

learning outcomes.

Summary of learning outcomes and assessment criteria Learning outcomes Assessment criteria to pass

On successful completion of

this module, you will: You can:

1. Understand the functions of

computer systems

1.1 Explain the role of computer systems in different

environments

1.2 Explain the hardware, software and peripheral

components of computer systems

1.3 Compare different types of computer system

2. Be able to design computer

systems

2.1 Produce a computer system design specification to

meet a client’s needs

2.2 Evaluate the suitability of a computer system

design specification

3. Be able to build and configure

computer systems

3.1 Build and configure a computer system to meet a


3.2 Test and document a computer system

4. Be able to undertake routine

maintenance on computer

systems

4.1 Perform routine maintenance tasks on a computer

system

4.2 Upgrade the hardware and software on a computer

system

These outcomes are covered in the module content and they are assessed in the form of written assignments and semester tests. If you comply with and achieve

all the pass criteria related to the outcomes, you will pass this module.

Introduction Page 3


Learning and assessment may be performed across modules, at module level or at outcome level. Evidence may be required at outcome level, although

opportunities exist for covering more than one outcome in an assignment.

Module content

1. Understand the functions of computer systems

Computer systems: this entails micro-computers, e.g. personal computers (PCs); mobile computers; mini-computers, e.g. mid-range servers and

workstations; mainframes, e.g. large-scale networking systems; super-computers, e.g. high performance systems; models and multiprocessing.

Environments: this entails home, business, computer gaming, networking,

real-time and communication.

Functions: this entails main components (arithmetic logic unit (ALU), control unit, memory and input/output (I/O) devices); connection, e.g.

buses; central processing unit (CPU) (control unit, ALU, registers and I/O devices); memory (random access memory (RAM), read-only memory

(ROM), registers and programmable caches); auxiliary storage and computer architecture.

Hardware: this entails the CPU; motherboard; power supply unit (PSU); cooling units; controllers; ports; main memory; memory types; battery;

specialised cards, e.g. peripheral component interconnect (PCI) and accelerated graphics port (AGP); networks; graphics; modems; sound;

optical drives and performance factors.

Software: this entails system software, e.g. operating systems (OSs); utility programs; library programs; translator programs; application

software, e.g. special purpose and bespoke; and performance factors.

Peripherals: this entails printers, plotters, cameras, scanners, keyboards, mouses, monitors, display adaptors, multimedia devices, storage media,

networking, portable drives, plug-and-play components and performance factors.

2. Be able to design computer systems

Needs analysis: this entails client and system requirements; problems/limitations with current/new system; functionality; costs;

timescales; resources and investigation/analytical techniques, e.g. interviews and questionnaires.

Introduction Page 4


Selection: this entails costs; client requirements; maintenance contracts; output required; compatibility; system integration, e.g. home

entertainment; storage capacity; accessibility; performance, e.g. speed, time, power, efficiency, effectiveness and usability; and alternative

solutions.

System specifications: this entails client and system requirements; system components; configuration; timescales; tools and resources; alternatives,

e.g. processor types; security measures and documentation.

3. Be able to build and configure computer systems

Health and safety: this entails practices and electrostatic precautions, e.g.

antistatic mats and wrist straps.

System installation: this entails hardware (assembling and disassembling a computer system), e.g. motherboard, CPU, heat sink and fan, memory,

PSU and connecting these to the internal components; hard disk and optical drives; specialised cards, e.g. graphics, network, modem and

audio; software, e.g. OS, application and utility; peripheral devices, e.g.

printers, scanners and cameras; and communication devices, e.g. modems and routers.

System configuration: this entails configuring the basic input-output

system (BIOS), e.g. date, time, power management and security; installing antivirus and security updates; updating user profiles;

configuring the desktop, icon and font size, colour, background and other menus; managing files and folders; setting files and folders sharing

permissions; and configuring peripheral and communication devices.

System testing: this entails fault detection; power-on self-test (POST); diagnostic faults; troubleshooting devices; technical support

documentation, e.g. reference manuals and online manufacturer support; testing hardware, e.g. I/O and peripheral devices; testing software and

documentation, e.g. test plans.

4. Be able to undertake routine maintenance on computer

systems

Software maintenance: this entails upgrading software, e.g. virus-definition files and patches/updates; scheduling maintenance tasks; utility

software, e.g. defragmentation, cleanup, backup and system profilers;

and third-party utility software, e.g. compression utilities and spyware/malware removal.

Introduction Page 5


Hardware maintenance: this entails upgrading hardware; installing and configuring new peripherals, e.g. printers and scanners; installing and

configuring additional or replacement devices, e.g. hard drives, memory, graphics, sound, optical media and networks; and cleaning equipment.

File management: this entails managing files and folders as well as

backup procedures.

Lectures Each week has four compulsory lecture hours for all students. It is

recommended that the lecture hours be divided into two sessions of two hours each, but this may vary depending on the campus.

Each week has a lecture schedule, which indicates the approximate time that

should be allocated to each activity. The week’s work schedule has also been

divided into two lessons.

Class exercises and activities

You will be required to complete a number of exercises and activities in class. These activities and exercises may also contribute to obtaining a pass,

therefore, it is important that you are present in class so that you do not forfeit

the opportunity to be exposed to such exercises and activities.

Activity sheets that are submitted should be kept by the lecturer so that they can be used as proof of criteria that were met, if necessary.

Information resources You should have access to a resource centre or library with a wide range of

relevant resources. Resources can include textbooks, e-books, newspaper

articles, journal articles, organisational publications, databases, etc. You can access a range of academic journals in electronic format via EBSCOhost. You

will have to ask a campus librarian to assist you with accessing EBSCOhost.

Introduction Page 6


Recommended information sources Anfinsin, D. 2010. IT essentials: PC hardware and software companion

guide. San Jose: Cisco Press.

Dick, D. 2009. The PC support handbook: the configuration and systems guide. Oxford: Dumbreck Publishing.

MacRae, K. 2002. The computer manual: the step-by-step guide to upgrading

and repairing a PC. Yeovil: Haynes Group.

MacRae, K. & Marshall, G. 2008. Computer troubleshooting: the complete step-by-step guide to diagnosing and fixing common PC problems. 2nd edition.

Yeovil: Haynes Group.

White, R. & Downs, T. 2003. How computers work. London: Que.

NOTE

Web pages provide access to a range of Internet information sources.

Students must use this resource with care, justifying the use of information gathered.

Using this Study Guide As we indicated earlier, the Study Guide is your main source of information for

this module.

The purpose of the Study Guide is to facilitate your learning and to help you to master the content of the material. It, further, helps you to structure your

learning and manage your time as well as provides outcomes and activities to help you master said outcomes.

The Study Guide has been carefully designed to optimise your study time and

maximise your learning, so that your learning experience is as meaningful and

successful as possible. To deepen your learning and enhance your chances of success, it is important that you read the Study Guide attentively and follow all

the instructions carefully. Pay special attention to the module outcomes at the beginning of the Study Guide and at the beginning of each unit.

It is essential that you complete the exercises and other learning activities in

the Study Guide as your module assessments (examinations, tests and assignments) will be based on the assumption that you have completed such.

Introduction Page 7


Purpose The purpose of the Study Guide is to facilitate the learning process and to help

you to structure your learning and to master the content of the module.

It is important for you to work through the Study Guide attentively and to follow all the instructions set out in such. In this way, you should be able to

deepen your learning and enhance your chances of success.

Structure The Study Guide is structured as follows:

Introduction

Unit 1 Introduction to computer systems

Unit 2 System components

Unit 3 System installation

Unit 4 System configuration

Unit 5 System testing

Unit 6 System maintenance and upgrade

Glossary

Bibliography

Individual units The individual units in the Study Guide are structured in the same way and

each unit contains the following features, which should enhance your learning process:

Unit title

Each unit title is based on the title and content of a specific

outcome or assessment criterion (criteria) as discussed in

the unit.

Learning outcomes and

assessment criteria

The unit title is followed by an outline of the learning

outcomes and assessment criteria, which will guide your

learning process. It is important for you to become familiar

with the learning outcomes and assessment criteria, because

they represent the overall purpose of the module as well as

the end product of what you should have learnt in the unit.

Learning objectives

Learning objectives, which follow the learning outcomes and

assessment criteria, are statements that define the expected

goals of the unit in terms of the specific knowledge and skills

that you should acquire as a result of mastering the unit

content. Learning objectives clarify, organise and prioritise

learning and they help you to evaluate your own progress,

thereby taking responsibility for your learning.

Introduction Page 8


Introduction The learning objectives section is followed by an introduction

that identifies the key concepts of the unit.

Content

The content of each unit contains the theoretical foundation

of the module and is based on the work of experts in the

field of the module. The theory is illustrated by means of

relevant examples.

Concluding remarks

The concluding remarks at the end of each unit provide a

brief summary of the unit as well as an indication of what

you can expect in the following unit.

Self-assessment

The unit ends off with a number of theoretical self-

assessment questions that test your knowledge of the

content of the unit.

Glossary

As you can see, we include a brief glossary at the end of the Study Guide. Please refer to it as often as necessary in order to familiarise yourself with the

most important abbreviations/acronyms of terms and concepts involved in computer systems.

The use of icons

Icons are used to highlight (emphasise) particular sections or points in the Study Guide, to draw your attention to important aspects of the work, or to

highlight activities. The following icons are used in the Study Guide:

Activity

This icon indicates learning activities/exercises that have to be completed, whether individually or in groups,

in order to assess (evaluate) your understanding of the content of a particular section.

Example

This icon points to a section in the text where relevant examples of a particular topic (theme) or concept are

provided.

Introduction Page 9


Learning outcome alignment This icon is used to indicate how individual units in the

Study Guide are aligned to a specific outcome and its assessment criteria.

Test your knowledge

This icon appears at the end of each unit in the Study Guide, indicating that you are required to answer self-

assessment questions to test your knowledge of the content of the foregoing unit.

Alignment between Study Guide, learning outcomes and assessment criteria

The following table reflects the alignment between the learning outcomes, assessment criteria and units in the Study Guide:

Learning outcomes Assessment criteria Study

Guide unit

1. Understand the

functions of

computer systems

1.1 Explain the role of computer systems in

different environments 1

1.2 Explain the hardware, software and

peripheral components of computer systems 1, 2

1.3 Compare different types of computer system 1

2. Be able to design

computer systems

2.1 Produce a computer system design

specification to meet a client’s needs 2, 3

2.2 Evaluate the suitability of a computer system

design specification 2, 4

3. Be able to build and

configure computer

systems

3.1 Build and configure a computer system to

meet a design specification 3, 4, 5

3.2 Test and document a computer system 5

4. Be able to undertake

routine maintenance

on computer systems

4.1 Perform routine maintenance tasks on a

computer system 6

4.2 Upgrade the hardware and software on a

computer system

Introduction Page 10


Concluding remarks At this point, you should be familiar with the module design and structure as

well as with the use of the Study Guide.

In Unit 1, we start with the actual module content by introducing computer systems.

Unit 1 – Introduction to Computer Systems Page 11


Unit 1: Introduction to Computer Systems

Unit 1 is aligned with the following learning outcome and assessment criteria:

Learning outcome

LO1 Understand the functions of computer systems

Assessment criteria

AC1.1 Explain the role of computer systems in different environments

AC1.2 Explain the hardware, software and peripheral components of computer systems

AC1.3 Compare different types of computer system

Learning objectives

After studying this unit, you should be able to:

Identify how to access system components Identify motherboard components and describe their functions

Distinguish between advanced technology extended (ATX) and proprietary motherboard form factors

Introduction

In this unit, we will focus on the types of computer system, their operation principles and configuration. We will discuss the different types of software

used by computer systems as well as their respective purpose. We will conclude by discussing the motherboard form factor, bus architecture and the

common components found on such.



1.1 Computer system basics

At an elementary level, a computer does the following:

It takes input

It processes such according to stored instructions It produces results as output

Activity

Write down as many computer input and output as you can think of.

A computer is seen as a machine that can be programmed to manipulate symbols. Its principal characteristics are:

It responds to a specific set of instructions in a sequenced manner

It can execute a pre-recorded list of instructions (a program/application) It can quickly process, store and retrieve large amounts of data in a

structured format

A computer can, therefore, perform complex and repetitive procedures quickly, precisely and reliably. In most cases, repetition is the key element allowing the

automation of complex tasks to aid human communication.

Modern computers are electronic and digital in nature and have immense

processing power. The actual machinery or components of a computer (wires, transistors and circuits) are called ‘hardware’ whereas the instructions and

data processing are called ‘software’. All general-purpose computers require the following hardware components:

Central processing unit (CPU): the heart of a computer; this is the

component that actually executes instructions organised in programs (software), which tell the computer what to do

Memory (fast, expensive, short-term memory): this enables a computer to store data, programs and intermediate results

Mass storage (slow, cheap, long-term memory): this enables a computer to permanently retain large amounts of data and programs between jobs;

common mass storage devices include disk and tape drives

Input devices: these are, usually, a keyboard and mouse; an input device is a conduit through which data and instructions enter a computer

Output devices: these can be a display screen, printer or other device that allows you to visualise what the computer has accomplished



1.2 Classification of computer systems

1.2.1 Principles of operation Based on the principles of operation, computer systems are classified into three

types (Figure 1), namely:

1. Analogue computers 2. Digital computers

3. Hybrid computers

Figure 1 – Computer types

Source: Elango, Jothi, Malaiarasu, Ramachandran & Rhymend-Uthariaraj (2005:15)

1.2.1.1 Analogue computers

Analogue computers are computing devices that work on a continuous range of values. Analogue computers give approximate results as they deal with

quantities that vary continuously; they, generally, deal with physical variables, such as voltage, pressure, temperature, speed, etc.

1.2.1.2 Digital computers

Digital computers operate on digital data, such as numbers; they use a binary

number system, in which there are only two digits, namely, 0 and 1. Each 1 is called a ‘bit’.

1.2.1.3 Hybrid computers

An analogue digital hybrid computer is designed using digital circuits, in which there are two levels for an input or output signal; these two levels are known

as ‘logic 0’ and ‘logic 1’. Digital computers can give results with more accuracy and at a faster rate. Since many complex problems in engineering and

technology are solved by the application of numerical methods, electronic digital computers are well suited to solving such problems. Hybrid computers

are a combination of the desirable features of analogue and digital computers.

Computers

Analogue Digital Hybrid



Example In a hospital’s automated intensive care unit (ICU),

analogue devices might measure a patient’s temperature, blood pressure and other vital signs. These measurements,

which are analogue in nature, might be converted into numbers and supplied to digital components in the

hospital’s system. These components, in turn, can be used to monitor the patient’s vital signs and send signals if any

abnormal readings are detected.

1.2.2 Configuration Based on performance, size, cost and capacity, digital computers are classified

into four types (Figure 2), namely:

1. Super-computers 2. Mainframe computers

3. Mini-computers 4. Micro-computers

Figure 2 – Digital computer types

Source: Elango [et al.] (2005:15)

1.2.2.1 Super-computers

Super-computers are the mightiest computers of all but, at the same time, the most expensive. Super-computers process billions of instructions per second.

They are, normally, used to solve intensive numerical computations, for example, stock analyses, special effects for movies, weather forecasting and

even sophisticated artworks.

Digital computers

Super-computers

Mainframe computers

Mini-computers

Micro-computers



1.2.2.2 Mainframe computers

Mainframe computers are capable of processing data at very high speeds (hundreds of millions instructions per second). They are large in size,

expensive and used to process large amounts of data quickly. Some of their most obvious customers are banks, airline and railway reservation systems,

aerospace companies executing complex aircraft design, etc.

1.2.2.3 Mini-computers

Mini-computers were developed with the objective to launch low cost computers. They are not as good as mainframe computers in terms of speed or

storage capacity. Some hardware features available in mainframes are,

furthermore, not included in mini-computer hardware in order to reduce costs. The mini-computer market has diminished somewhat as buyers have moved

towards less expensive but increasingly powerful personal computers (PCs).

1.2.2.4 Micro-computers

The invention of the micro-processor (single chip CPU) gave birth to micro-computers. They are much cheaper than mini-computers and can be classified

into the following categories (Figure 3):

Workstations PCs

Laptop computers Palm PCs

Figure 3 – Micro-computer types


Although equipment may vary from the simplest computer to the most powerful, the major functional units of computer systems remain the same,

namely, input, processing, storage and output.

Micro-computers

Work-stations

Personal computers

Laptop computers

Palm PCs



Workstations

Workstations (Figure 4) are desktop machines that are mainly used for graphics-intensive applications. They have more processor speed than PCs.

Figure 4 – Workstation

Source: http://www.albacore.co.uk/news/xp-workstation-upgrade-deals

Workstations use sophisticated display screens featuring high resolution colour

graphics. They are used for numeric- and graphics-intensive applications, such as computer aided design (CAD), the simulation of complex systems and

visualising the results of such simulations.

PCs

Today, PCs are the most popular computer system. Desktop computers are also known as ‘home computers’; they are, usually, easier to use and more

affordable than workstations. They are self-contained and intended for an individual user. Desktop computers are most often used for word processing

and small database applications.

http://www.albacore.co.uk/news/xp-workstation-upgrade-deals



Laptop computers

Laptop computers (Figure 5) are portable computers that fit in a briefcase. Laptop computers, also called ‘notebook computers’, are portable, functional

and popular with travellers who need a computer that can go with them.

Figure 5 – Laptop computer

Source: www.wired.co.uk/reviews/laptops/2012-10/samsung-series-5-550p-review

Palm PCs

Palm PCs were manufactured with the intention to have a computer that could be hand-held. This device was, however, phased out in 2000.

1.3 Software ‘Software’ refers to a program that enables a computer to do something

meaningful. It is the planned, step-by-step instructions required to turn data

into information. Software can be classified into two categories (Figure 6), namely:

1. System software

2. Application software

Figure 6 – Software types


Computer software

System software

Application software

http://www.wired.co.uk/reviews/laptops/2012-10/samsung-series-5-550p-review



1.3.1 System software

System software consists of general programs written for computers. These programs provide the environment in which to run application programs.

System software comprises of programs, which interact with hardware at a very basic level. They are a basic necessity in computer systems as they

ensure the proper functioning of such. System software serves as the interface between hardware and the user (Figure 7). The operating system (OS),

compilers and utility programs are examples of system software.

Figure 7 – System software


The most important type of system software is the OS. An OS is an integrated set of specialised programs that is used to manage the overall operations of a

computer. It acts like an interface between the user, computer hardware and software.

Application software

System software

Hardware



Every computer must have an OS to run other programs. Disk Operating System (DOS), Unix, Linux and Windows are some of the most common OSs.

Compiler software translates a source program (user written program) into an object program (binary form) (Figure 8). Specific compilers are available for

computer programming languages, such as FORTRAN, COBOL, C and C++. Utility programs support a computer in terms of specific tasks, such as file

copying, sorting and linking.

Figure 8 – Compiler software


1.3.2 Application software

Application software consists of programs designed to solve user problems. They are used to accomplish specific tasks rather than just managing computer

systems. Application software is controlled by system software, which manages hardware devices. Some typical examples of application software are railway

reservation systems, game programs, word processing software and weather forecasting programs. Among application software we can find programs that

are designed for specific tasks, for example, word processors, spreadsheets and database management systems.

1.3.2.1 Word processing software

One of the most commonly used software packages is word processing software. Anyone who has used a computer as a word processor knows that it

is far more than a fancy typewriter. The advantage of word processing over a typewriter is that you can make changes without retyping an entire document.

The entire writing process is thus transformed by modern word processing software. This type of software, further, allows you to create, edit, format,

store and print text and graphics. Some commonly used word processors are Microsoft Word, WordStar and WordPerfect.

Source program

Compiler

Object program



1.3.2.2 Spreadsheet software

Spreadsheet software packages allow users to manipulate numbers. Repetitive numeric calculations, the use of related formulae and the creation of graphics

and charts are some of the basic spreadsheet tools. These tools afford business people the opportunity to try different combinations of numbers to obtain

results quickly. Lotus 1-2-3 and Microsoft Excel are two of the most famous spreadsheet applications.

1.3.2.3 Database management system software

A database management system is a collection of programs that enable users

to store, modify and extract information from a database. A database

organises information internally. Computerised banking systems, automated teller machines (ATMs), and airline and railway reservation systems are

examples of database applications.

1.4 Motherboard

A printed circuit board (called the ‘motherboard’, ‘system board’ or ‘main

board’) houses the processor, chipset, memory and expansion slots. The type of motherboard influences the system speed and upgrade options. There are a

great many motherboard manufacturers, including Abit, AOpen (Acer), ASUSTek, Intel and Gigabyte. A typical motherboard consists of the

components shown in Figure 9:

Figure 9 – Intel ATX motherboard

Source: Doctor, Dulaney & Skandier (2012:6)



1.4.1 Form factor

The form factor of a motherboard describes its shape, physical layout and the type of case and power supply unit (PSU) that can be used. Two motherboards

may have exactly the same functionality but different form factors; the difference is thus the layout of the components on the motherboard. Most

motherboards are based on the ATX or Micro-ATX design.

1.4.1.1 ATX and Micro-ATX

The ATX specification was developed by Intel in 1995 to provide a new design

for PC motherboards, updating the previous advanced technology (AT) form factor. Full size ATX boards are 12" wide and 9.6" deep (305 x 244 mm). The

Micro-ATX standard specifies a 9.6" square board with fewer expansion slots.

1.4.1.2 Front panel connectors

Components on the front panel of the chassis connect to headers on the motherboard. Typically, front panel connectors can include:

Power button/reset button (soft power): on modern computers, the power

button sends a signal to the PC that can be interpreted by the OS rather than actually switching the PC off. However, holding down the power button

for a few seconds will cut the power. Some older computers might also

feature a physical reset button in addition to the power button Power light: there may be a separate power light emitting diode (LED) but

this is, usually, part of the button Hard disk drive (HDD) activity lights: these show when an internal hard disk

is being accessed Universal serial bus (USB) ports: a computer will, normally, feature one or

two front USB ports to connect peripherals as well as more ports on the back Audio ports: these allow for headphones and a microphone to be connected

1.4.2 Bus architecture

PCs consist of many internal components, all of which communicate with each other via a bus. Physically, a bus is implemented on to the motherboard as tiny

wires (called ‘traces’) running between components. The bus carries information being processed by the computer (data) and information about

where the data is located in memory (address). The bus also carries power to a component as well as the timing signals that synchronise components.

Bus architecture, usually, refers to an ‘expansion bus’, used to connect

peripheral devices; however, a variety of buses exist within PCs. In addition, the way in which bus designs are implemented has changed considerably along

with the development and improvement of PC technology.



1.4.2.1 Internal and external buses

One way of categorising the types of bus is to divide them into internal and external buses:

An internal (or local) bus connects core components, such as the CPU,

memory and system controllers An external bus (or expansion bus) allows for additional components to be

connected to a computer; these components could be peripheral (located outside the case) or adapter cards (located inside the case)

External bus technologies do not necessarily extend outside the computer

case. For example, peripheral component interconnect (PCl), the most popular

expansion bus standard, provides connections to internal adapter cards only. A genuine external bus (such as small computer system interface (SCSI), USB or

Firewire) extends the bus wires outside the computer case using cabling.

The distinction between internal and external bus types has also become a lot less clear as one bus technology will be used to perform both types of role (for

example, PCl Express).

1.4.2.2 System clock and bus speed

The system clock synchronises the operation of all PC parts and provides the basic timing signal for the CPU. Clock speeds are measured in megahertz

(MHz) or gigahertz (GHz).

The clock consists of a clock generator that sets up a timing signal and clock

multipliers that take the timing signal produced by the generator and apply a multiplication factor to produce different timing signals for different types of

bus.

1.4.2.3 Parallel and serial bus types

Historically, most bus designs used parallel technology. The width of a parallel bus (32-bit, etc.) and the clock speed determine bandwidth (or transfer rates).

Recent bus designs, notably USB, Firewire and PCI Express, use serial communication; the data rate for serial communication is based on the clock

speed and encoding mechanism.

1.4.3 Components All motherboards have connectors for the same types of component: CPU,

memory, disk drives, peripherals and so on. However, the type and number of these connectors depend on the models supported.



1.4.3.1 CPU socket and chipset

New motherboards are, generally, released to support new CPU designs. Because technology changes rapidly, a given motherboard will only support a

limited number of CPU models. The CPU is, typically, inserted into a squarish socket, located close to memory sockets, and then covered by a heat sink and

fan.

The system chipset is soldered onto the motherboard and cannot be upgraded. The type of chipset on the motherboard can affect the type of processor,

processor speed, multiprocessing support, type and amount of system memory, and type(s) of system bus.

The chipset consists of a number of controllers that handle the transfer of data between the CPU and various devices, such as:

System memory controller

PS/2 keyboard and mouse controller Input/output (I/O) controller that handles serial ports, parallel ports, floppy

disks, disk drives and expansion buses Controllers for any integrated video, sound, network (cabled and wireless) or

SCSI interfaces

1.4.3.2 Chipset and memory architecture

CPU models are closely tied to the chipset and memory sub-system. This means that there is far less scope for upgrading the CPU than used to be the

case. You could not, for instance, take a motherboard designed for the Core 2

CPU and plug an advanced micro devices (AMD) Phenom into it. Both the physical interface (socket) and system architecture have diverged along

proprietary lines since the old socket interface used by the original Pentiums.

The link between the CPU and system memory is a key factor in determining system performance.

1.4.3.3 Northbridge/Southbridge

In Legacy PC motherboards, the chipset is split into two sections, namely:

1. Northbridge

2. Southbridge

The Northbridge can be one or more chips on the motherboard. Its main

function is system memory controller, connecting the processor to random access memory (RAM). The Northbridge also supports other faster

components, such as the accelerated graphics port (AGP) bus. It is connected to the processor through the front side bus (FSB).



The Southbridge is, usually, one chip. It is designed to control all of the I/O functions not handled by the Northbridge (often older, slower technologies),

such as USB, serial, parallel, industry standard architecture (ISA), PCI, system basic input-output system (BIOS), disk controllers and onboard audio or

network adapters. The Southbridge is connected to the CPU via the Northbridge (usually via the PCI bus) (Figure 10):

Figure 10 – A typical motherboard chipset

Source: Doctor [et al.] (2012:6)

As video and hard disk technologies improved, the shared PCI bus linking

Northbridge and Southbridge became a bottleneck to performance. Newer CPUs and chipsets use different designs, with Intel and AMD both introducing

different architectures.

1.4.3.4 Memory

PC memory can be categorised as either RAM or read-only memory (ROM), each of which with a different function. A motherboard will, generally, have

between two and four slots for installation of system RAM. It also houses a ROM BIOS chip.

RAM

RAM is the working memory of a PC. Program code is loaded into RAM so that it can be accessed and executed by the processor. RAM also holds data (for

example, the contents of a spreadsheet or document), while it is being modified. System RAM is volatile; it loses its contents as soon as power is

removed.



System RAM is, normally, dual inline memory modules (DIMMs) fitted to motherboard sockets. The type of sockets and chipset determine the types of

system memory that can be installed. The capabilities of the memory controller and number of physical sockets, in turn, determine how much memory can be

fitted.

Flash memory is a non-volatile type of RAM, increasingly used in place of, or alongside, hard disks for persistent storage of data.

BIOS

BIOS provides the industry standard program code that operates the

fundamental PC components and ensures that the design of each

manufacturer’s motherboard is PC compatible. BIOS code is manufacturer specific, therefore, BIOS chips cannot be swapped between different

motherboards. However, most use flash ROM, which can be upgraded. The BIOS is often known as ‘firmware’ as it consists of both the physical chip

(hardware) and the programs coded into such (software).

The ROM BIOS can be identified by a label on the chip showing the name of the manufacturer and a version number (in Windows) via the System

Information (msinfo32) utility.

The BIOS also provides the following features:

Power-on self-test (POST) diagnostic tests A real-time clock (RTC) that keeps track of the current date and time

Setup menus that allow for low-level hardware configuration (stored in

complementary metal-oxide semiconductor (CMOS) RAM) to be viewed and edited

CMOS RAM

CMOS RAM stores a PC’s basic configuration (for example, disk types, amount

of memory installed, current time and date, etc.). This prevents the need for reconfiguration when powering on a PC. CMOS describes the manufacturing

process used to make RAM chips. CMOS devices require very little power to operate and use a small battery to maintain their settings. A CMOS battery is a

coin lithium battery.

Expansion slots

Expansion slots allow for plug-in adapter cards to be installed in a PC to extend

the range of functions that it can perform. There are a number of different expansion bus types and many different types of adapter card.



Concluding remarks

In this unit, we introduced the basic components of a computer system. All computer systems consist of hardware, software, memory and I/O devices,

each with a specific function. Not all computers are the same; some are built

for a specific purpose, however, understanding the core components and composition of such is useful when analysing any system.

In the next unit, we will continue to investigate computer system components.

Self-assessment

Test your knowledge

1. Define an OS, application software, micro-computer, mainframe and bus.

2. Briefly discuss the types of computer memory and their respective uses.

Unit 2 – System Components Page 27


Unit 2: System Components

Unit 2 is aligned with the following learning outcomes and assessment criteria:

Learning outcomes

LO1 Understand the functions of computer systems

LO2 Be able to design computer systems

Assessment criteria AC1.2 Explain the hardware, software and peripheral

components of computer systems AC2.1 Produce a computer system design specification to

meet a client’s needs AC2.2 Evaluate the suitability of a computer system


Learning objectives


Describe the functions and capabilities of connection interfaces Describe the functions and capabilities of input devices

Install and configure peripheral devices

Introduction In the previous unit, you learnt about the types of computer system, the types

of software that they use, the motherboard components and bus architecture.

In this unit, we will discuss the key concept of data transmission. The unit will

focus on the various ports and connection interfaces used by computer systems as well as the various types of connection interface suitable for

particular components. We will conclude the unit by discussing basic I/O peripheral devices.



2.1 Signalling

A computer transmits data via electrical signals, which are stored in components, called ‘transistors’. The electrical pathways within a computer or

through cabling that carry signals are referred to as ‘buses’. Numerous

different bus technologies have been and are used to build computers as well as many different signalling methods.

Generally speaking, older computer bus types (such as serial and PS/2 ports or

video graphics array (VGA) display ports) use a method, called ‘single-ended signalling’. Newer buses (such as USB, Firewire and PCI Express) use

differential signalling. The advantage of differential signalling is that it allows for the use of lower voltages, thereby reducing power consumption and heat.

Another distinction between signalling methods is between parallel and serial

communication. Some bus types transfer data in parallel, which means that there are multiple physical wires to carry signals. A parallel bus that is 32 bits

wide would transfer 32 bits in each operation. Parallel communication was popular in the 1990s; modern bus technologies use serial communication. This

means transferring one bit at a time but working at a higher frequency.

Signalling can, further, either be digital or analogue. Computers use digital

signalling, where pulses in an electrical signal refer to discrete binary values (representing 1 or 0). Analogue is a continuous, variable signal. Computers

need to translate between digital and analogue signals (for example, for video or audio signalling on analogue equipment) by sampling the analogue signal.

2.2 Data units

Computers work with binary data. The fundamental unit of data storage is a bit (binary digit), which can represent 1 or 0. A bit can be measured in multiples

using kilobit (KB) and megabit (Mb). However, in terms of today’s computers, these values represent tiny amounts. Larger units are more typically used to

describe file size, memory capacity and disk storage capacity, for example:

1 024 KB equate to a megabyte (MB) (1 048 576 bytes) 1 024 MB equate to a gigabyte (GB) (1 073 741 824 bytes)

1 024 GB equate to a terabyte (TB) (1 000 000 000 000 bytes)

File size and memory capacity are always quoted as binary measurements. For example, when you see that Windows reports 2 GB memory, this means 2 048

MB, not 2 000 MB.

Storage capacity is, typically, quoted by vendors in decimal measurements. For

example, a hard disk advertised with a capacity of 300 GB has an ‘actual’ capacity of 286 GB.



Binary values are often converted to decimal. Hexadecimal notation is another convenient way of referring to long strings. Hexadecimal has 16 characters to

represent (0…9 plus A, B, C, D, E, F). Therefore, it only takes one hexadecimal character to represent four binary characters.

2.3 Ports

2.3.1 External ports

I/O ports allow for additional devices to be connected to a PC. Some ports are designed for a particular type of device, such as a graphics port. Other ports,

such as a USB, support different types of device.

External ports appear at the rear or front of a PC through slots cut into the case. They are part of an expansion card of the motherboard.

2.3.1.1 PC99 connectors

On modern PCs, connectors and ports should conform to the PC99 standard, which defines colour codes for external ports, namely:

PS/2 mouse (green)

PS/2 keyboard (purple) Parallel port (burgundy)

Serial port (turquoise) USB port (colours vary)

RJ-45 network port (colours vary) Audio port (audio in (light blue), audio out (lime) and microphone (pink))

2.3.1.2 Legacy port types

Ports are often described as male, meaning that they have pin connectors, or female, meaning that they have hole connectors. This ‘gender’ orientation

means that it is virtually impossible to connect ports incorrectly.



2.3.2 PS/2 ports

The PS/2 (or mini-DIN) port (Figure 11) is used to connect a keyboard and mouse. Both PS/2 keyboard and mouse ports are 6-pin female. To avoid

confusion, the system case, usually, has symbols and colour coding (green for mouse and purple for keyboard) to differentiate between them. PS/2 is a serial

bus. Note that the sockets are not interchangeable; a mouse plugged into the keyboard port will not function and vice versa.

Figure 11 – PS/2 ports


2.3.3 Serial ports A serial port (or RS-232) is called such because data is transmitted over one

wire one bit at a time. Start, stop and parity bits are used to format and verify data transmission. A serial port supports data rates of up to 115 kilobits per

second (kbps).

Serial ports are, generally, associated with connecting external modems; this function had largely been superseded by USB.

The RS-232 standard for serial ports specified a 25-pin interface, however, in

practice, PC manufacturers use the cheaper 9-pin D-shell port (see Figure 12). A serial port is also referred to as a ‘communication (COM) port’.



2.3.4 Parallel ports

A parallel port, also known as the ‘printer’ or ‘Centronics port’, is called such because data is transferred simultaneously over eight wires (there are extra

‘handshake’ wires for controlling the signals) (see Figure 12). This restricts the maximum length of cabling as tiny differences in the properties of wires cause

delays in the signal (data skew), which get worse the farther the signal travels.

2.3.5 VGA ports The distinctive blue, 15-pin VGA port (HD15F/DE-151) (Figure 12) is the

standard analogue video interface for PC devices. Almost all graphics adapters and display screens continue to support it.

Figure 12 – Parallel, VGA and serial ports


The connector is a D-shell type (HD15M) with screws to secure it to the port.

The interface is analogue, meaning that it carries a continuous, variable signal. The interface carries red, green and blue (RGB) component video signals.

Better quality cables (generally speaking, the thicker the better) use shielded

coaxial wiring and support longer lengths at better resolutions. Low quality cables may only be able to support 800 x 600. Such cables may be marketed

with the highest resolution that such can support (ultra extended graphics array (UXGA), 1 600 x 1 200, for instance).



2.3.6 USB ports

The USB (Figure 13) has become the standard means of connecting plug-and-play peripheral devices to PCs. Unlike serial and parallel ports, USB supports

compact connectors and high data rates.

Figure 13 – USB ports


A USB consists of a host controller and up to 127 devices. A device can be a hub (providing ports for additional devices) or function. Functions are divided

into classes, such as human interfaces (keyboards and mouses), mass storage devices (disk drives), printers, audio devices and so on. Power is supplied by

the host at 5V and a single device may draw up to 500 mA or 2.5W. Devices, such as compact disc (CD) writers or printers, requiring more power, must be

connected to an external power supply.

Another feature of USB is that the bus supports hot swapping. A PS/2, serial or

parallel device may require the system to be restarted as devices are added or removed. A USB host can detect and configure a hot swappable device without

requiring a restart.

Table 1 provides a summary of USB speeds:

Table 1 – USB speeds




There are two types of standard USB connector, namely:

1. Type A: for connecting to a host or hub port 2. Type B: for connecting to a device

The USB-mini form factor is now deprecated but there are still plenty of

devices that require such. There are mini Type A and Type B standards; the Type B plugs and receptacles predominate (Figure 14):

Figure 14 – USB-mini Type B connectors


USB-mini has five pins rather than four; the extra pin is designed to support the USB on-the-go (OTG) specification that allows for a port to function as

either a host or device. For example, a port on a smartphone might operate as a device when connected to a PC and as a host when connected to a keyboard.

The extra pin communicates which mode the port is in.

The USB-micro was specified in 2007 and is now the preferred format. Micro connectors are about half the thickness of mini connectors. Like USB-mini,

there are five pins to support USB OTG. There are receptacles that can accept either micro Type A or Type B (Figure 15):

Figure 15 – USB-micro Type B connector




There is also USB 3 whose receptacles often have a blue connector tab to distinguish them. USB plugs and receptacles have nine contacts rather than

four but the Type A plugs are physically compatible with older USB ports. For example, you can plug a USB 3 device into a USB 2 port and it will work at

high speed data rates or, conversely, you can plug a USB 2 device into a USB 3 port and it will work at high speed rates. USB 3 Type B cables and plugs are

not compatible with USB 1.1 or USB 2.0 devices.

The maximum cable length for low speed devices is three metres while for full speed and high speed the limit is five metres. Vendors may, however, provide

longer cables. Super speed capable cables do not have an official maximum length, however, up to about three metres is recommended.

2.3.7 SCSI

The SCSI uses a parallel data stream with hardware handshaking and control signals. One SCSI host bus adapter (HBA), also known as a ‘host adapter’, can

control multiple devices attached via internal ribbon cables or external SCSI cables. The SCSI standard also defines a command language that allows for

the host adapter to identify which devices are connected to a bus and how they are accessed.

There are many different SCSI standards and types, thus configuration is

relatively complex. SCSI devices are, typically, used on server class hardware

rather than on desktop PCs.

There are numerous SCSI connectors. The most common are:

IDCSO: a 50-pin internal connector used with early SCSI devices (SCSI-1) CN50: a 50-pin Centronics style connector used for external connections in

early SCSI devices D825: a 25-pin connector used primarily by Apple and Iomega (zip drives)

H068: a 68-pin connector used for internal and external ports; 68-pin adapters support wide SCSI

Single connector attachment (SCA): an 80-pin connector that incorporates a power connector and configuration wires, allowing for hot swappable drives

2.3.8 IEEE 1394 (Firewire)

The Firewire bus, based on the IEEE 1394 standard, is another modern serial bus. IEEE 1394 was developed from SCSI but uses serial rather than parallel

communication as well as much smaller connectors. Firewire is similar to USB but has not received such mainstream support from PC vendors. If a

motherboard does not provide Firewire ports, an expansion card can be fitted.



A single bus can connect up to 63 devices. As in the case of USB, the bus is powered and supports plug-and-play as well as hot swapping. The maximum

transfer rate is 400 mbps. Firewire supports an isochronous transfer mode where the data rate to a particular device is guaranteed, making it well

matched to the transfer of real-time data, such as video. The original Firewire 400 standard uses 6-pin ‘alpha’ connectors and cabling (Figure 16):

Figure 16 – Firewire 6-pin port


The maximum cable length between two devices is 4.5 metres. There is also a

4-pin unpowered connector, often referred to as ‘i.LINK’.

The IEEE 1394b (Firewire 800) standard supports transfer rates of up to 800

mbps and increased power from the bus (up to 45W) to support larger devices without the need for a separate power source. Firewire 800 uses 9-pin ‘beta’

connectors and cabling. Older devices can be plugged into a port using a 6-pin to 9-pin converter (‘bilingual’) cable.

IEEE 1394b also supports different cabling media for networking use over

longer distances (up to 100 metres).

2.3.9 High definition multimedia interface (HDMI) and other

display ports

HDMI (Figure 17) supports both video and audio digital streams as well as remote control and digital content protection. HDMI only carries a digital

signal; it does not support analogue monitors. HDMI uses a proprietary 19-pin Type A connector.



Figure 17 – HDMI interface


Composite video combines the colour information from the three video

channels (RGB) into a single signal (Figure 18). It is an analogue only interface. Composite video, typically, uses a single Radio Corporation of

America (RCA) jack (often colour-coded yellow).

Figure 18 – Composite video cable


S-video (Figure 19) carries an analogue video signal. In Europe, the Scart connector is more common even though such is not supported on PC

equipment. S-video, typically, uses a 4-pin mini-DIN connector.

Figure 19 – S-video 7-pin port


Component (RGB) video uses three RCA jacks. Component video has higher

bandwidth than S-video or composite video feeds and is widely found on better quality audio-visual equipment.



2.4 Peripheral devices

2.4.1 Input devices Basic input devices are peripherals that enable a user to enter data and select

commands.

2.4.1.1 Keyboards

A keyboard (Figure 20) is the longest serving type of input device. Historically, keyboards are connected via a 6-pin mini-DIN PS/2 port. This is coloured

purple to differentiate it from the identical mouse connector. Many keyboards are now USB or wireless (infrared or Bluetooth).

Figure 20 – A standard U.S. keyboard layout

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Extended PC keyboards feature a number of special command keys (<Alt>

and <Ctrl>) as well as keys, such as <Print Screen>, <Num Lock>, <Scroll Lock>, <Start>, <Shortcut> and <Function>. A numeric keypad

can function as a calculator or as an additional set of arrow keys (the function is toggled by <Num Lock>). Multimedia keyboards may also feature

programmable keys and buttons that can be used for web browsing, playing music, etc.

2.4.1.2 Mouses

A mouse is the main type of input device for graphical software. Mouses use

the same interface as keyboards (the PS/2 port is colour-coded green).

There are three types of mouse:

1. Mechanical mouse: this contains rollers to detect the movement of the ball

housed in the mouse case. As the user moves the mouse on a mat or other firm surface, the ball is moved and the rollers and circuitry translate the

motion to move a cursor on the screen 2. Optical mouse: this uses LEDs to detect movement over a surface

3. Laser mouse: this uses an infrared laser, which gives greater precision than an optical mouse

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Another distinguishing feature of different mouse models is the number of buttons (between two and four), which can be customised to different

functions as well as the presence of a scroll wheel, used for scrolling and as an extra clickable button.

Mouses are also distinguished by their size and shape. Smaller mouses are

useful with portable systems whereas others are marketed on the basis of their ergonomic shape.

2.4.1.3 Joysticks/game pads

PC games are mostly designed for use with a mouse and keyboard but some

games (for example, flight simulators) benefit from the use of a joystick or

game pad. Historically, joysticks used a DB-15 port, usually located on the sound card, but now devices use USB connectors. Joysticks can also be used

as input devices by people who have difficulty using a mouse or keyboard.

2.4.1.4 Biometric devices

Biometric devices are used to perform authentication (identifying someone as a valid user of a computer or network). Biometric devices associated with

computer equipment tend to be thumb- or fingerprint readers. These may be standalone devices connected via a USB port or incorporated onto a computer

chassis, keyboard or mouse.

2.4.1.5 Scanners

A scanner (Figure 21) is an input device that allows for information, such as

images or text, to be input into a computer. It can read images or text printed on a piece of paper and translates such into a form that the computer can use;

that is, it is used to convert images (photos) and text into a stream of data. Scanners are useful for publishing and multimedia applications.

Figure 21 – Scanner




2.4.1.6 Bar code readers

Bar code readers are used in places, such as supermarkets, bookshops, etc. A bar code is a pattern printed in lines of different thickness. A bar code reader

scans the information on a bar code and transmits such to a computer for further processing (Figure 22). The system allows for fast and error-free entry

of information.

Figure 22 – Bar code reader


2.4.1.7 Digital cameras

A digital camera is an input device used mainly to capture images. It takes still

photographs, stores and sends these as digital input. Digital cameras are a modern and popular input device.

2.4.1.8 Touch sensitive screens

A touch sensitive screen is a type of display screen that has a touch sensitive

panel. It is a pointing device that enables a user to interact with a computer by touching the screen. You can use your fingers to directly touch the objects on

the screen. A touch screen senses the touch on an object and communicates the object selection to the computer.

2.4.2 Output devices

Output is anything that comes out of a computer. An output device is capable of presenting information from a computer.



2.4.2.1 Monitors

A monitor (Figure 23) is a commonly used output device, sometimes called a ‘display screen’. It provides a visual display of data and is connected to a

computer. Monitors are similar in appearance to a television set.

Figure 23 – Monitor

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Initially there were only monochrome monitors but, gradually, monitors could display colour. They display images and text; the smallest dot that can be

displayed is called a ‘pixel’ (picture element). The resolution of a monitor improves as the number of pixels increase. Most monitors have a 4:3 width to

height ratio, called ‘aspect ratio’.

The number of pixels that can be displayed vertically and horizontally gives the resolution of a monitor. The resolution of a monitor determines the quality of

the display. Some popular resolutions are 640 x 480 pixels, 800 x 600 pixels and 1 024 x 768 pixels. A resolution of 1 024 x 768 pixels will produce a

sharper image than 640 x 480 pixels.

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2.4.2.2 Printers

A printer is an output device that prints text or images on paper or other media, such as transparencies. By printing, you create what is known as a

‘hard copy’. There are different types of printer, which vary in speed and print quality. The two main types are (Figure 24):

1. Impact printers

2. Non-impact printers

Figure 24 – Printer types


Concluding remarks In this unit, we introduced signalling methods used to transmit data over

parallel and serial communication. The fundamental unit of data storage notation in binary and hexadecimal were discussed. Understanding additional

devices and the I/O ports to which they connect was highlighted as useful when designing a computer system for a given scenario.

In the next unit, we will investigate computer system installation.

Self-assessment

Test your knowledge

1. Explain signal transmission in parallel and serial communication.

2. Briefly discuss the types of mouse.

Unit 3 – System Installation Page 42


Unit 3: System Installation


Learning outcomes


LO3 Be able to build and configure computer systems

Assessment criteria AC2.1 Produce a computer system design specification to

meet a client’s needs AC3.1 Build and configure a computer system to meet a


Learning objectives


Understand the health and safety procedures associated with computer systems

Understand how a hard drive works and identify related performance factors Understand how a basic redundant array of independent disks (RAID) is

configured

Describe the capabilities and uses of the different types of removable storage

Describe the different types of memory Understand the characteristics of double-sided, dual channel, error checking

and correction (ECC) and registered memory types Understand technologies for improving performance, such as architecture,

multitasking, multiprocessing, multicore and cache Describe features, such as clock speed, overclocking and power

management Understand how to plan for installations and upgrades

Describe the different installation methods Prepare and complete hard disk partitions, file systems and attended

installations



Introduction

In this unit, you will be introduced to health and safety procedures associated with computer systems. Your background pertaining to the different system

components will assist you to further learn about each component and how

such can be installed or removed. The previous unit’s information will also assist you to develop better computer systems by using appropriate system

components. You will, further, learn how to install an OS and how to prepare Windows disk setup using different media options.

3.1 Safety procedures

3.1.1 Health and safety laws

While specific regulations may vary from country to country and state to state, in general, employers are responsible for providing a safe and healthy working

environment. Employees, in turn, are responsible for using equipment in the workplace in accordance with the guidelines given to them as well as to report

hazards. Employees should not interfere with safety systems, including signs, warnings or devices, such as firefighting equipment. Employees should also not

introduce or install any devices, equipment or materials without authorisation or without making a health and safety assessment of such.

A company’s health and safety procedures should be outlined in a handbook, possibly as part of employee induction. Health and safety procedures should:

Identify what to do in the event of fire or other emergency

Identify the responsible individual to contact in case of emergency (for example, for overall health and safety, nominated first aiders, fire marshals,

etc.) Identify hazardous areas in the workplace as well as their associated

precautions Describe best practice for the use and care of the workspace and its

associated equipment Establish an incident reporting procedure for detecting and eliminating

workplace hazards and accidents



The general emergency situation procedure is as follows:

Raise the alarm and contact emergency services, giving them a description of the emergency and your location

If possible, make the scene safe. For example, if faced with a fire, establish that you have an escape route or, if faced with electric shock, disconnect the

power (if it is safe for you to do so) If you have undergone training and it is safe to do so, do what you can to

assist. For example, give first aid or use firefighting equipment

Circumstances could, however, dictate that you do things differently than outlined above. It is thus vital that you keep calm and do not act rashly.

3.1.2 Electricity

Electrical equipment can give an electric shock if such is broken, faulty or incorrectly installed. An electric shock can cause severe burns or even kill.

Know that currents can pass through metal and most liquids, thus neither should be allowed to come into contact with any device installations.

Always disconnect electrical equipment, such as PCs and printers, from any

power sources (including removing laptop batteries) before cleaning or servicing such.

Damaged components or cables are also a risk and should be replaced or isolated immediately. It is important to test electrical devices regularly (the

frequency will depend on the environment in which such is used). Portable appliance testing (PAT) performed by a qualified electrician or technician will

ensure that devices are safe to use.

An electrical device must be fitted with a fuse appropriate to its power output. A fuse blows if there is a problem with the electricity supply, breaking the

circuit to the power source. Fuses come in different ratings, such as 3A, 5A and 13A. A device’s instructions will indicate what rating of fuse to use; most

computer equipment is rated at 3A or 5A. If the fitted fuse is rated too low, it will blow easily; if the rating is too high, it may not blow when it should (this

will allow too much current to pass through a device).



If multiple devices need to be attached to a single power point, an appropriate strip of sockets should be used (Figure 25). If too many devices are attached

to a single point, there is a risk that they will overheat and cause a fire. ‘Daisy-chaining’ one strip to another is not recommended. Strips may be fitted with a

surge suppressor, which provides some protection against surges in the supply.

Figure 25 – Overloaded (left) and proper use (right) of power strips

Source: GTS Learning (2013:5)

3.1.2.1 Equipment grounding

Electrical equipment must be grounded or ‘earthed’. If there is a fault that causes metal parts in the equipment to become live, grounding provides the

proverbial ‘path of least resistance’ for the current to flow away harmlessly. Most computer products (PCs, printers, etc.) are connected to building ground

via power plugs. Note that the large metal equipment racks often used to house servers and network equipment must also be grounded. Never

disconnect a ground wire; if it has to be removed, ensure that it is replaced by a competent electrician.

3.1.2.2 Personal safety

The human body is a conductor and resistor, thus current will pass through it

and make it heat up, manifesting as a burn if the current is strong enough. Current can interfere with the body’s nervous system, which also uses

electrical signals. This might manifest as a spasm or paralysis (from electric

shock) or, in severe cases, cause a heart attack.

High voltages (over 30V) are more dangerous because they have the power to push more current through you (the skin’s resistance drops dramatically at

higher voltages), but it is the current that causes the actual damage (this is why static electricity is not dangerous, despite high voltages). More current will

flow if a larger area of the body is exposed.



Always remember the following:

Do not work on electrical systems (especially an energised circuit) unless you have a good understanding of the risks and appropriate safety

procedures Disconnect the power to a circuit if you must handle such and always test

live parts with a multimeter to ensure that no voltage is present Before performing work within a PC, always remove the power cord. After

removing the cord, hold down the power button for a few seconds to ensure that the circuits are de-energised. Similarly, before opening the chassis of a

laptop, remove the alternative current (AC) adapter and battery Always use properly insulated tools and never grip a tool by its metal parts.

It is especially important not to touch the live parts of multimeter probes as

these may be connected to an energised circuit. Handle the probes by their insulated sheaths only

Take care not to touch any part of a circuit with both hands to reduce the risk of serious shock (the ‘hand in pocket’ rule reduces the chance that

current will pass through your chest) Ensure that your hands and the surrounding working area are dry (sweat

can make your hands more conductive). Do not leave any spill hazards in the vicinity

Do not wear jewellery, a wrist watch or other items, such as name badges, that may dangle and cause a shortcircuit or become trapped by moving

parts

3.1.3 Cathode ray tube (CRT) safety Power supplies, such as those inside system units, CRT monitors, liquid crystal

display (LCD) displays (inverters) and laser printers can carry extremely high levels of voltage. Charges held in capacitors can persist for hours after the

power supply is turned off. You should not open these units unless you have been specifically trained to do so. Adhere to all printed warnings and never

remove or break open any safety devices that carry a warning.

3.1.4 Electric fire Faulty electrical equipment can pose a fire risk. If the equipment allows more

current to flow through a cable than the cable is rated for, the cable will heat up. This could ignite flammable material in close proximity to the cable. If a

wire does start a fire, it is important to use the correct type of extinguisher to put such out. Many extinguishers use water or foam, which can be dangerous

if used near live electrical equipment. The best type to use in such an instance is a carbon dioxide (CO2) gas extinguisher (CO2 extinguishers have a black

label). Dry powder extinguishers can also be used, though these may damage equipment. You should also always ensure that the electricity supply is turned

off. This should happen automatically (the fuses for the circuit should trip) but ensure that you know the location of the power master switches for a building

nonetheless.



3.1.5 Cable management and lighting techniques

A trip hazard is caused by putting objects in people’s paths. When installing equipment, ensure that cabling is secured using cable ties or cable

management products (Figure 26). Ensure that cables running under a desk cannot be kicked out by the user’s feet. Do not run cabling across walkways

and when servicing equipment, do not leave devices in walkways or near the edge of a desk. Be careful when putting heavy or bulky equipment down and

ensure that such cannot topple over.

Figure 26 – Built-in cable management


Lifting heavy objects in the wrong way can damage your back, however, lifting

and manual handling risks are not limited to particularly heavy objects. An object that is large or awkward to carry could also cause you to trip over or

walk into something. An object that has sharp or rough edges or contains a hot or corrosive liquid could cause you to cut or hurt yourself. If necessary, you

should obtain protective clothing (gloves and possibly goggles).

To lift a heavy object safely, plant your feet around the object with one foot slightly toward the direction in which you are going to move. Bend your knees

to reach the object while keeping your back as straight as possible and comfortable; keep your chin up. Find a firm grip on the object, then lift

smoothly by straightening your legs (do not jerk the object up). Carry the object while keeping your back straight.

To lower an object, reverse the lifting process; keep your chin up and bend at the knees. Take care not to trap your fingers or to lower the object on to your

feet.

If you cannot lift an object because it is too awkward or heavy, get help. If you need to carry an object for some distance, ensure that the route is

unobstructed and that the pathway (including stairs or doorways) is wide and tall enough.



3.1.6 Static electricity and electrostatic discharge (ESD)

Static electricity is a very high voltage stored in an insulated body. Although the voltage is high, the amount of ESD current that it can sustain is very low,

thus static electricity is not that harmful. It can, however, be slightly painful, for example, you may have felt a small shock when reaching for a metal door

handle.

The human body consists mostly of water and so does not generate or store

static electricity very well. Unfortunately, our clothes are often made of synthetic materials, such as nylon and polyester, which act as good generators

of static electricity and provide insulating layers that allow for charges to accumulate.

Humidity and climate also affect the likelihood of ESD. The risk increases

significantly during dry, cool conditions when humidity is low. In humid conditions, such as before or during a storm, the residual charge will bleed into

the environment before it can increase sufficiently to be harmful to electrical components.

A component, such as a memory or logic chip, is composed of fine, conductive

metal oxides deposited on a small piece of silicon. Its dimensions are measured in fractions of a micron (one millionth of a millimetre). Any static

electricity discharged into this structure will flash over (spark) between the

conductive tracks, damaging or even vaporising them. This may make the chip completely unusable. If not, it is likely to fail at some later time. Damage

occurring in this way can be hidden for many months and may only manifest itself in occasional failures.

To protect components and equipment from ESD damage, ensure that your

body and clothing are drained of static electricity before starting work; if possible, work in an uncarpeted area. The simplest (but least effective) means

of self-grounding is to touch an unpainted metal part of a PC (such as the PSU) before you handle a sensitive component. This is only a temporary solution as

static charge could build up again.

Do not leave a PC plugged in when opening the case for a service. Your safety is more important than the risk of damaging some PC components.



Where possible, handle vulnerable components by holding on to the edges of the plastic mounting card; avoid touching the surfaces of the chips themselves.

Using an anti-ESD wrist strap (Figure 27) can dissipate static charges more effectively. Such a wrist band should fit snugly around your wrist to maximise

contact with the skin. Do not wear it over clothing. The wrist strap grounding is achieved by either using a grounding plug that plugs into a wall socket or a

crocodile clip that attaches to a grounded point or an unpainted part of a computer’s metal chassis.

Figure 27 – Anti-ESD wrist strap and grounding cord


Ensure that the wrist strap has a working current limiting resistor for safety (straps should be tested daily). Do not use a grounding plug if there is any

suspicion of a socket fault, a fault in the building’s electrical wiring or if the wiring is not regularly inspected and tested. An anti-ESD service mat (Figure

28) is also useful. Sensitive components can be placed on the mat safely.

Figure 28 – Anti-ESD service kit with mat




3.2 Mass storage devices

System memory provides a fast storage medium for the OS and applications, however, it is volatile, meaning that data cannot be stored without a power

supply. Non-volatile storage devices or mass storage devices hold data when a

system is powered off. Removable mass storage devices allow for data to be archived from a PC as well as for such to be transferred between PCs.

Mass storage devices use either magnetic or optical technology to store data.

Storage capacity ranges from 1.44 MB for a standard 3.5" floppy disk to multiple GBs for tape storage.

Some storage devices are fitted as internal components. In the case of

removable storage devices, a drive is positioned at the front of the case so that media can be inserted and removed. HDDs do not need user access and so do

not need to be positioned near a face plate.

External storage devices are increasingly popular for backup and data transfer as they offer more capacity than traditional removable storage disks. A device,

such as an external HDD, would, typically, be connected to a PC via USB or a

Firewire port.

3.2.1 HDDs

Even with the advances in speed and capacity of other types of storage technology, the HDD still remains the primary method of persistent storage.

On a workstation, a HDD will store the OS files, application program files, system software files (such as drivers) and user data. On a server, the HDD

will store individual user files and shared sources of information, such as databases.

Original HDDs stored as little as 10 MB – the same amount of space as about seven floppy disks – but advances in technology have enabled disks of over

1 TB to be created – the same as about 600 000 floppy disks.

3.2.1.1 HDD construction

Data is stored on a number of metal or glass platters coated with a magnetic substance. The top and bottom of each platter is accessed by its own

read/write head, moved by an actuator mechanism. The heads do not actually touch the surface of the platters. The platters are mounted on a spindle and

spin at high speed; the heads ‘float’ above them at a distance of less than a millionth of an inch.



Figure 29 represents this with the following numbered items:

1. Platters 2. Spindle

3. Read/write heads 4. Actuator

Figure 29 – HDD with drive circuitry


A HDD unit is kept sealed to maintain a constant air pressure (this is important as it keeps the drive heads at the correct distance from the platters) and to

prevent the entry of dust.

Each side of each platter is divided into circular tracks and each track contains a number of sectors, each with a capacity of 512 bytes. The collection of tracks

in the same place on each platter is called a ‘cylinder’. This formatting is also

referred to as the ‘drive geometry’.

HDDs have two main formats, namely:

1. 3.5": the mainstream type used in PCs 2. 2.5": a form factor that is used for laptops and as portable external drives

3.2.1.2 HDD performance

HDD performance is a measure of how fast such can read and write data.

There are a number of factors that determine overall HDD performance.

The first factor is the speed at which the disks can spin (measured in revolutions per minute (RPM)); the higher the RPM, the faster the drive. High

performance drives are rated at 15 000 or 10 000 RPM; the average

performance is 7 200 or 5 400 RPM.



RPM is, further, a factor that determines access time (measured in milliseconds (ms)), which is the delay that occurs as the read/write head locates a

particular position on the drive. A high performance drive will have an access time of below 4 ms; a typical drive might have an access time of around 9 ms.

The internal transfer rate, or data/disk transfer rate, of a drive is a measure of

how fast read/write operations are performed on the disk platters. The external transfer rate, often simply described as the ‘transfer rate’, measures how fast

data can be transferred to the CPU across a bus. Cache memory can help to sustain better transfer rates. A high performance disk may feature a 4 MB or

better cache.

Generally, the burst transfer rate is also quoted; this is the maximum possible

transfer rate under ideal conditions and thus cannot be sustained over long periods of time.

Some HDDs are now being fitted with a substantial cache of flash memory to

improve performance; these are referred to as ‘hybrid drives’.

Another crucial factor that influences HDD performance is reliability. Reliability is rated by various statistics, including mean time between failures (MTBF),

which is the number of hours that a device should operate (under optimum conditions) before a critical incident can be expected, and life expectancy,

which is the duration for which a device can be expected to remain reliable.

All drives now feature self-monitoring analysis and reporting technology (SMART) to pass status information and alerts back to monitoring software.

This can provide advance warning that a drive is about to fail.

Some of the major HDD vendors include Seagate, Western Digital, Maxtor,

Hitachi, Fujitsu, Toshiba and Samsung.

3.2.2 Solid state drives (SSDs)

Solid state storage devices use a type of non-volatile electrically erasable programmable read-only memory (EEPROM), called ‘flash memory’. Flash

memory is non-volatile because it does not need a power source to retain information. Compared to other types of storage, flash memory is very small

and light. Mass manufacturing has seen prices fall to affordable levels as

storage capacity ranges from 512 MB to 256 GB.



Flash memory is also being incorporated into a new generation of SSDs designed to replicate or supplement the function of HDDs (Figure 30):

Figure 30 – HP SSD with SATA interface


The advantages of flash memory-based SSDs are that the lack of moving parts makes them quieter, more power efficient and less prone to catastrophic

failure. Read times are enhanced because seek time and, consequently, the effect of file fragmentation, is eliminated. They are also less susceptible to data

loss in the event of power failure.

The main disadvantage is the high cost; a 64 GB SSD costs slightly more than a 2 TB HDD (a 1 TB SSD can cost the same as a top-end server). SSDs can

also perform worse than HDDs when writing data and serving large files. Flash

chips are, further, susceptible to their own type of degradation over the course of many write operations, thus the OS must use wear levelling routines to

optimise the usable life of the device.

SSDs are available as either standalone units or hybrid drives. In a hybrid drive, the SSD portion functions as a large cache, containing data that is

accessed frequently. The magnetic disk is only spun up when non-cached data is accessed. This reduces power consumption but can degrade performance.



3.2.3 HBAs

HBAs provide a connection point for internal mass storage devices, such as hard drives, CD/digital versatile disc or digital video disc (DVD) drives and tape

drives. The interface between these drives, the host adapter and the rest of the system is a type of bus. There are three main bus standards for attaching

internal storage devices to a PC, namely:

1. Parallel advanced technology attachment (PATA)

2. Serial advanced technology attachment (SATA) 3. SCSI

HBAs are commonly described as ‘drive controllers’. Technically, a controller is

the circuitry in a disk that allows for such to put data on a bus, which the HBA shuttles to the CPU or RAM.

3.2.3.1 PATA

The PATA interface was the principal mass storage interface for desktop PCs

for many years. PCs supporting PATA may come with one or two host adapters or channels, called ‘primary integrated drive electronics’ (PRl IDE) or

‘secondary IDE’ (SEC IDE).

A single PATA channel is now more typical if the motherboard also supports

SATA. Each PATA channel supports two devices (0 and 1); they are, usually, labelled as ‘master’ and ‘slave’.



A PATA drive features a 40-pin port but, typically, uses 80 wire-shielded cables (required for UDMA4 or better transfer modes). A PATA cable is supposed to be

up to 18" long. Each PATA cable, typically, has three connectors, one for the motherboard and one for each device. Most new cables are ‘cable select’,

which allows for the master and slave devices to be identified by the position of the connector on the cable (Figure 31). Pin 1 on the cable must thus be

oriented with pin 1 on the connector. On the cable, pin 1 is identified with a red stripe. The connectors are also keyed to prevent them from being inserted

the wrong way around.

Figure 31 – Cable select PATA


3.2.3.2 SATA

SATA (Figure 32) was developed to address the limitations of PATA. It is now

the most popular means of attaching internal storage drives, though most motherboards retain at least one PATA host adapter.

Figure 32 – SATA cable




As the name suggests, SATA transfers data in serial format. This allows for thinner, longer, more flexible cables (up to 39") with smaller 7-pin connectors.

Each SATA host adapter supports a single device.

The first commercially available SATA standard supported speeds of up to 1.5 gigabytes per second (gbps). This standard was quickly augmented by SATA

Revision 2 (3 gbps) and then SATA Revision 3 (6 gbps).

Another key advantage of SATA over PATA is that SATA is a hot swappable interface. This means that a compatible drive can be connected or

disconnected while the system is running.

3.2.3.3 External hard disks

External hard disks have become very popular for backup, additional storage

and as a means of transferring files. Some external disks are designed for capacity (from 200 to 500 GB) while others are designed for portability.

External disks are, typically, packaged in a drive enclosure. The drive

enclosure provides USB or Firewire ports; some models support Ethernet network connections (referred to as ‘network attached storage’ (NAS)). The

drive enclosure also provides for an external power supply, if the drive is too large to be powered over USB, and the casing protects the drive from damage.

3.2.4 Installing disk drives

Storage devices are located in 3.5" (hard and floppy drives) and 5.25" bays (CD/DVD and tape drives) (Figure 33):

Figure 33 – HP Compaq showing Bezel (1) and 5.25" (2) drive bays




When adding or removing storage devices (or performing any type of work inside the PC case), ensure that you make a backup of any data stored on local

drives.

Before you remove storage devices, you should remove the power supply and signal cables. Signal (or data) cables are flat, grey ribbon cables that connect

the device to the adapter card or motherboard (Figure 34). Try to pull the plug rather than the cable; hard drive (Molex) power connectors have special

‘shoulders’ for this purpose (Figure 35):

Figure 34 – Removing data cables


Figure 35 – Removing Molex connectors


Once the cables have been removed from the storage device, undo the screws

that hold such to the case (Figure 36):

Figure 36 – Unscrewing a drive unit




If the device does not slide out backwards, try sliding it out forwards (Figure 37). You may have to remove the front panel of the PC in such a case.

Figure 37 – Removing storage devices


Some drives are stored in caddies that screw into the case. To remove the

drive you may first need to unscrew the caddy. In most cases, you will need to remove the second side panel.

3.2.4.1 Installing PATA disk drives

PATA supports two devices per channel (port). One device on each channel

must be configured as the ‘master’ and the other as the ‘slave’. The general norm is to configure the main hard disk (boot disk) as the primary master and

the additional device (such as an optical drive) as the secondary master. Third

and fourth devices should be configured as slaves on each channel. If there are insufficient PATA ports, a HBA card can be used.

To install a PATA disk drive, follow the following procedure:

Locate a spare 3.5" drive bay or remove an existing unit by unplugging the

cables from the back and then unscrewing the drive from the chassis. Some drives screw directly onto the chassis while others are screwed onto rails so

that the drive can be slid in and out (this also, usually, means that you do not have to remove the secondary panel) or screwed into a removable cage.

Hard drives can be oriented horizontally or vertically



Set the jumpers on the drive to indicate whether it is master, slave or cable select. A jumper is set by sliding the clip over two of the available pins (you

can use your fingers or needle nose pliers to position the clip) (Figure 38). The jumper diagram is, usually, printed on the drive, otherwise consult the

drive vendor’s documentation

Figure 38 – Hard drive with Molex power connector (1), configuration jumper (2)

and PATA port (3)


Screw the drive into the bay. Do not over tighten the screws Connect the PATA cable to the drive, taking care that pin 1 on the cable and

port are oriented correctly (most ports have a notch to help orient the

cable). If using cable select, ensure that you attach the correct connector; PATA cables are often quite short and bulky making connecting two drives a

troublesome task, especially if they are not in adjacent bays Connect the other end of the PATA cable to the appropriate IDE channel port

on the motherboard (Figure 39):

Figure 39 – IDE ports on the motherboard


Connect a spare Molex connector from the power supply to the 4-pin port on the drive. The connectors are keyed so that you cannot insert them the

wrong way around Check that the cables are all secure and then refit the parts of the case.

Ensure that cables do not restrict air flow around the case or obstruct the operation of fans, especially around the CPU, memory and graphics adapter.

Use cable ties to keep cabling neat and tidy



Once the drive has been physically installed, there are two further checks that need to be performed before such can be used:

1. Check that the device has been recognised by the computer’s BIOS. If the

drive is not listed in the startup configuration pages, enter CMOS Setup and check that the drive’s host adapter is enabled

2. When the drive is recognised in BIOS, you can access such using Windows Setup or the OS to format and partition it. Partitioning the drive defines

one or more discrete storage areas on the same physical disk. This is useful for installing multiple OSs or for defining system and user data storage

areas. You may see references to ‘low-level formatting’; this is the division of the disk surface into sectors. This is done at the factory by the

manufacturer. Each partition can be formatted using a different file system

(in Windows this means either file allocation table (FAT) or new technology file system (NTFS)). The choice of file system is driven by software

compatibility

3.2.4.2 Installing SATA disk drives

SATA configuration is much simpler than PATA. Each drive is connected to a SATA port on the motherboard or to a SATA host adapter (Figure 40). The

connectors are keyed to prevent incorrect insertion. There are no device settings to configure, thus, generally speaking, you should install the boot

drive into the lowest numbered port (SATA0).

Figure 40 – SATA ports


Some drives only feature newer SATA power connectors. If your PSU does not have any SATA power connectors, you will need an adapter to connect a Molex

power connector to such. If the drive has a Legacy Molex power connector, you should only use one of the connectors (do not plug a power cable into both).



3.2.4.3 Installing SCSI disk drives

Depending on the age of the equipment, SCSI configuration can be quite complex so you should refer to the vendor’s setup instructions carefully. Try to

ensure that equipment configuration and service records are kept up-to-date so that you have accurate documentation about the SCSl configuration.

To install a SCSI disk drive, follow the following procedure:

Check that the drive is a SCSI type that is compatible with the host adapter

If necessary, set the device identity (ID) to a unique number on the chain. On an internal device, the ID is, usually, configured via jumpers using the

settings diagram provided by the vendor; external devices, usually, have

click wheels. A wide SCSI bus allows for IDs from 0 to 15; the boot hard drive is, usually, set to ID 0. You should not use ID 7 as this is, normally,

reserved for the host adapter. The host adapter may configure device IDs automatically

Enable or disable lamination on the device (the first and last devices in a chain must be terminated).This may be configured via a jumper setting or

by physically installing a terminator onto the device Screw the drive into the bay and connect it to the host adapter using a

suitable SCSI cable Connect to the power supply using a Molex connector

3.2.4.4 Installing SSDs

A SSD uses flash memory instead of glass platters and read/write heads. A

hybrid drive is a normal HDD with a large flash memory cache. SSDs use the

SATA interface and are thus installed in the same way as a HDD.

3.2.5 RAID

With RAID, hard disks can act as backups for each other to increase reliability and input tolerance or they can act together as one very large drive.

RAID can also mean ‘redundant array of inexpensive disks/devices’.

The RAID Advisory Board defines RAID levels. The most common levels are

numbered from 0 to 6, where each level corresponds to a specific type of fault

tolerance. Only levels 0, 1 and 5 are of relevance at desktop level.

It is possible to implement RAID using either hardware or software.



3.2.5.1 Hardware solutions

A hardware solution refers to creating volumes from an array of physical disks; it is an operation supported by a plug-in controller card or by the motherboard,

independent of the installed OS (Figure 41). Hardware solutions are principally differentiated by their support for RAID levels. Entry-level controllers might

support only RAID 0 or 1 while mid-level controllers might add support for RAID 5 and 10.

Figure 41 – Configuring a volume using RAID controller firmware

Source: http://www.adrc.com/raid-10.html

In addition, hardware RAID is able to hot swap a damaged disk (replace the

failed unit without shutting down Windows), thereby keeping the system operational at all times. When a new disk is installed, the RAID controller

transparently synchronises such with the remaining disks in the set.

On the downside, hardware RAID is more expensive than a software solution and may lock you into a single vendor solution.

Older hardware RAID solutions used SCSI disks. Modern low cost solutions

may use SATA while serial attached SCSI (SAS) is a popular technology for server machines.

3.2.5.2 Software solutions

Windows provides the option to set up software-based RAID using standard disks and controllers, however, most desktop versions of Windows are

restricted to striping, which provides no fault tolerance. In a software solution, IDE/advanced technology attachment (ATA) and SCSI disks can be combined

in an array (USB or Firewire connected drives are not supported). A software solution is cheaper as RAID controller cards can be expensive.

http://www.adrc.com/raid-10.html



3.2.5.3 Hot swappable drives

A system configured for RAID might support hot swappable drives. While this is, usually, a server feature it might be implemented on high-end workstations.

Rather than using cabled connectors, hot swappable drives plug (or ‘mate’) into a combined data and power port on the enclosure. This means that drives

can be easily added and removed from the front of the case without having to open the chassis. The drives are secured and released from the enclosure

using a latch (Figure 42):

Figure 42 – HP MediaSmart server with hot swappable drive enclosure


3.3 Removable storage

3.3.1 Optical disc storage CDs and DVDs, depending on who you believe, are mainstream storage

formats for consumer multimedia, such as music and videos. Both formats have been adapted for data storage to use with PC systems. CD and DVD

drives used with PCs can also play consumer versions of discs.

The data version of a CD (CD-read-only memory (CD-ROM)) became ubiquitous on PC systems as such has sufficient capacity (700 MB) to deliver

most software applications. DVD is an improvement on CD technology and delivers substantially more capacity (up to 17 GB). DVDs are used for software

installations (Windows Vista and Windows 7) as well as for games and multimedia.

3.3.1.1 CD construction

A CD is a layer of aluminium foil encased in protective plastic, which can also incorporate a label or screen printed image on the non-playing side. The foil

layer contains a series of pits and spaces (called ‘lands’), arranged in a spiral. The changes between pits and lands are used to encode each bit. A standard

CD is 120 millimetre (mm) in diameter and 1.2 mm thick.



3.3.1.2 Recordable CDs (CD-R)

A recordable version of a CD (CD-R) was developed in 1999. Rather than a premastered layer of foil with pits and lands, CD-Rs feature a layer of

photosensitive dye. A special laser is used to transform the dye, mimicking the pits and lands of a normal CD, in a process, called ‘burning’. Most ordinary CD

players and drives can read CD-Rs but they may not play back properly on older equipment.

CD-R is a type of write once read many (WORM) media. Data areas, once

written, cannot be overwritten. However, a rewritable (or multisession) disc format (CD-RW) has also been developed. This uses a heat sensitive

compound with properties that can be changed between crystalline and

amorphous by a special laser. There is some concern over the longevity of recordable CDs and DVD media as cheaply manufactured discs have shown a

tendency to degrade and become unusable (sometimes over the space of just a few years).

3.3.1.3 CD drives

A CD drive consists of a spindle motor (to spin the disc), laser, lens (to read

the disc) and tracking system (to move the laser and lens assembly). The mechanism for inserting a CD is either tray- or slot-based. A drive may feature

audio play and volume control as well as a headphone jack. Drives are considerably larger than herd discs (5.25").

Drives also feature a small hole that accesses a disc eject mechanism (insert a

paperclip to activate the mechanism). This is useful if the standard eject

button will not work or if the drive does not have power.

CD drives are rated according to their data transfer speed. The original drives had a data transfer rate of 150 kbps. Subsequently, drives are available that

offer multiples of the original rate; this would be around 52 for new models, offering transfer rates in excess of 7 mbps.

Many CD drives also function as recordable/rewritable CD burners or writers.

Such drives feature three speeds, always expressed as the record/rewrite/read speed (for example, 24X/16X/52X). A feature to look out for on such drives is

burn-proof technology, which prevents discs from being ruined by buffer under run errors (where the software cannot supply the drive with the data to write

quickly enough).



3.3.1.4 DVDs

A DVD is similar to a CD but with a different encoding method, higher density discs and a shorter wavelength laser. DVD discs are also thinner and can be

dual layer and/or double-sided (a DVD is two 0.6 mm discs sandwiched together). The different permutations result in the storage capacities in Table

2:

Table 2 – DVD storage capacities

Standard Capacity Description

DVD-5 4.7 GB Single layer and single-sided

DVD-9 8.5 GB Dual layer and single-sided

DVD-10 9.4 GB Single layer and double-sided

DVD-18 17.1 GB Dual layer and double-sided

DVD-video Up to 17.1 GB

Commercially produced DVDs using mpeg encoding and

chapters for navigation (can be single or dual layer and

single- or double-sided)

DVD-audio 8.5 GB Format for high quality audio (superior sampling rates

and 5.1 surround sound)


DVDs also feature a higher transfer rate, with multiples of 1.32 mbps

(equivalent to 9X CD speed). The fastest models feature a 16X read speed.

Similar to CDs, some DVDs are recordable and rewritable; some even support

dual layer recording.

There are two slightly different standards for recordable (DVD-R) and rewritable (DVD-RW) DVDs, namely, DVD+R and DVD+RW. Most drives can

read all formats but write in either + or - format. Many consumer DVD players can play DVD±R discs.

Consumer DVDs, further, feature copy protection mechanisms (digital rights

management) and region coding. Region coding, if enforced, means that a disc can only be used on a player from the same region.

Some DVD players are ‘multiregion’ but some discs feature protection

mechanisms that disable playback in such machines. PC software is, usually, not region coded, with the exception of some PC game discs.



3.3.1.5 Blu-ray discs

Blu-ray discs (BDs) have emerged as the next generation format for distributing consumer multimedia and are also likely to be used to distribute

high bandwidth applications, such as video games.

Blu-ray is principally required to cope with the demands of high definition (HD) video recording and playback. HD requires more bandwidth and storage space

because it uses a much higher resolution picture (1 920 x 1 080 compared to 720 x 480 or 720 x 576) and better quality audio (digital surround sound).

A BD works on fundamentally the same principle as DVD but with a shorter

wavelength laser (a 405 nanometre (nm) blue laser compared to a DVD’s 650

nm red laser). This means that the discs can be higher density though the cost of components to make such is considerably greater.

A standard BD has a capacity of 25 GB per layer whereas mini-discs can store

7.8 GB per layer. Dual, triple and quad layer discs are available but there are currently no double-sided formats.

The base speed for Blu-ray is 4.5 mbps and the maximum theoretical rate is

12X (54 mbps). Currently, most drives are 4X or 8X; 2X is the minimum required for movie playback.

Generally speaking, BD players are also capable of CD and DVD playback.

Recordable (BD-R) and re-recordable (BD-RE) drives and discs are also available. BD-R is often available at the same speed as playback while BD-RE

is, usually, half of playback speed.

Similar to DVDs, consumer BDs are likely to be digital rights management

protected and may be region coded.

3.3.2 Installing optical or tape drives

Installing an optical (CD, DVD or Blu-ray) drive or tape drive is fundamentally the same as installing a HDD, except that you will fit it to a 5.25" drive bay.

You may also need to remove a plate from the front Bezel. Most optical and tape drives need to be oriented horizontally.

Drives can be PATA, SCSI or SATA. PATA and SCSI configuration on these devices is the same as for HDDs.



3.3.2.1 Flash memory devices

There are many ways of packaging flash memory. One of the most popular is a USB or ‘thumb’ drive. This type of drive simply plugs into any spare USB port.

Another popular type of packaging is a memory card, used extensively in

consumer digital imaging products, such as digital still and video cameras. There are several proprietary types of memory card. Some popular examples

include compact flash (CF), secure digital (SD), Sony Memory Stick and xD. The largest cards have up to 128 GB storage capacity.

Many PCs are fitted with memory card readers with slots that will

accommodate most of the sticks on the market.

Another use for flash memory is as the main storage for electronic devices,

such as smartphones, mp3 players and so on.

Data transfer rates vary quite widely between different devices, which are rated on the same system as CDs, using multiples of 150 kbps, with the fastest

devices working at up to 200X read speed (or 38 mbps, where the write speed is, typically, about two-thirds of the read speed).

3.3.2.2 Tape drives

Magnetic tape drives provide a low cost per byte method of creating system

backups. They may be internal or external units, supplied with SCSI, USB or Firewire interfaces. Some of the most popular formats are:

Quarter-inch cartridge (QlC): this is the oldest tape drive format still in use. Tapes can store up to 4 GB. The Travan backup format is a development of

the QIC system; tapes can store up to 10 GB of uncompressed data Digital audio tape (DAT): this uses a digital format. DAT backup systems

conform to a standard, called ‘digital data storage’ (DDS), and support up to 36 GB of uncompressed capacity

8 mm tape systems: these offer up to 200 GB capacity storage in a cartridge that appears identical to 8 mm video tapes, although it uses a much higher

quality magnetic media. The 8 mm standard was mainly developed by the Advanced Intelligent Tape (AIT) Forum, sponsored notably by Sony



3.4 System memory

3.4.1 Memory types System memory is the main storage area for programs and data when a

computer is running. System memory is necessary because it is much faster than accessing data in a mass storage system, such as a HDD.

System memory is a type of volatile memory, namely, RAM. ‘Volatile’ means

that data is only retained in the memory chips while there is a power source.

Non-volatile memory does not require a constant power source to store data. Examples include ROM and flash memory.

A large quantity of system memory is essential for the running of a PC. It

determines the PC’s ability to work with multiple applications at the same time

as well as with larger files. Each new generation of software tends to take up more memory space. If there is not enough system RAM, the memory space

can be extended by using disk space (virtual memory), however, as noted above, accessing the HDD is very slow compared to accessing RAM.

Some notable RAM vendors include Kingston, Crucial (Micron), Corsair, PNY

and Integral.

A number of different RAM technologies have been used for system memory in PCs over the years.

3.4.1.1 Dynamic RAM (DRAM)

DRAM stores each data bit as an electrical charge within a single bit cell. A bit

cell consists of a capacitor to hold the charge that the cell represents (1 if

there is a charge and 0 if there is not) and a transistor to read the contents of the capacitor.

Each bit cell is very small thus the electrical charge gradually dissipates,

causing the memory cell to lose its information. In order to preserve information, DRAM has to be refreshed periodically by accessing each bit cell at

regular intervals. These refresh cycles slow down the DRAM operation but it supports high densities (more MB per memory module) at relatively low cost.

3.4.1.2 Synchronous DRAM (SDRAM)

Many different types of DRAM have been developed and become obsolete. In

the mid-1990s, variants of SDRAM were used for system memory. SDRAM is called such because it is synchronised to the system clock. It has a 64-bit data

bus and runs at the speed of the FSB.



Table 3 summarises SDRAM:

Table 3 – SDRAM

Model Clock speed Bandwidth

PC66 66 MHz 533 mbps

PC100 100 MHz 800 mbps

PC133 133 MHz 1 066 mbps


SDRAM works with Pentium, Pentium MMX, Pentium II and Pentium III Intel CPUs (as well as with their AMD K5/6/7 and Athlon equivalents).

SDRAM for desktop PCs is packaged in 168-pin DIMMs (Figure 43). The

notches (keys) on the module prevent it from being inserted into a slot the wrong way around. Memory slots look similar to expansion slots but have

catches on each end to secure the memory modules.

Figure 43 – SDRAM packaged in a 168-pin DIMM


3.4.1.3 Double data rate SDRAM (DDR SDRAM)

DDR SDRAM is an updated type of SDRAM, where data is transferred twice in one cycle (‘double-pumped’). DDR is very popular and used on many

motherboard designs for both Intel and AMD CPUs. There are four DDR standards, matching different system clock speeds (Table 4):

Table 4 – DDR SDRAM

Type Bus speed Maximum data rate

DDR-200/PC-1600 100 MHz 1.6 gbps

DDR-266/PC-2100 133 MHz 2.1 gbps

DDR-333/PC-2700 167 MHz 2.7 gbps

DDR-400/PC-3200 200 MHz 3.2 gbps




SDRAM is referred to by clock speed (PC66, PC100 and PC133). DDR and Rambus chips are labelled using the maximum theoretical bandwidth

(PC-1600, PC-2100, etc.), largely for marketing reasons. For example, DDR-200 refers to the bus speed (100 MHz double-pumped) and PC-1600

refers to the peak bandwidth (200 MHz x 8 bytes).

DDR is being replaced by DDR2 and DDR3 SDRAM (Table 5); these increase bandwidth by doubling or quadrupling the bus speed (as opposed to the speed

at which the actual memory chips work). This produces scalable speed improvements without making the chips too unreliable or hot. The drawback is

increased latency as data takes longer to access on each chip. Latency is offset by improving the memory circuitry.

Table 5 – DDR2 and DDR3 SDRAM

Type Memory speed Bus speed Maximum data rate

DDR2-400/PC2-3200 100 MHz 200 MHz 3.2 gbps









DDR3-2133/PC3-17000 266 MHz 1 066 MHz 17.066 gbps


There is also a graphics double data rate (GDDR) type of memory, which is a

type of graphics card memory similar to DDR2 and DDR3.

The data rates quoted for RAM are maximum peak rates; actual throughput will thus vary.



DDR for desktop system memory is packaged in 184-pin DIMMs whereas DDR2 and DDR3 are both packaged in 240-pin DIMMs but are not compatible (the

modules and slots are keyed differently) (Figure 44). Faster modules, typically, feature heat sinks because of the higher clock speeds.

Figure 44 – Corsair ValueSelect DDR2 SDRAM packaged in a 240-pin DIMM


3.4.1.4 Rambus DRAM (RDRAM)

RDRAM is proprietary memory technology developed by the Rambus Corporation. It was used with some Pentium 4 motherboards (all socket 423

and some socket 478) but was quickly superseded by DDR SDRAM.

RDRAM has a 16-bit (single channel) or 32-bit (dual channel) bus width but runs at a much higher speed than SDRAM (266 MHz and more) as well as

being double-pumped. 16-bit RDRAM is packaged in 184-pin Rambus inline memory modules (RIMMs) (Figure 45) while 32-bit modules are packaged in

232-pin RIMMs, both of which feature heat sinks because of the high clock

speeds.

Figure 45 – Samsung RDRAM packaged in a 184-pin RIMM




Table 6 summarises RDRAM:

Table 6 – RDRAM

Model Type Clock speed Bandwidth

PC600 Single channel (16-bit) 266 MHz 1 066 mbps




RIMM 3200 Dual channel (32-bit) 400 MHz 3 200 mbps

RIMM 4200 Dual channel (32-bit) 533 MHz 4 200 mbps


Most motherboards supporting RDRAM are dual channel. Single channel RIMMs

have to be installed in matching pairs in a dual channel motherboard, but dual channel modules can be installed singly. Regardless of single or dual channel

modules, unused slots need to be filled with a terminator, called ‘continuity RIMM’ (CRIMM).

3.4.1.5 Laptop memory

Laptop RAM is packaged in a smaller module, called ‘small outline DIMM’ (SODIMM) (Figure 46). Both DDR and DDR2 use 200-pin packages, but the

key position for DDR2 is slightly different to prevent insertion in a slot designed for DDR. DDR3 uses a 204-pin package.

Figure 46 – Corsair ValueSelect SODIMM


Legacy SDRAM uses a mat pin package. The memory is, typically, fitted into slots that pop-up at a 45° angle to allow for chips to be inserted or removed.



3.4.2 Memory components

3.4.2.1 Memory chips

The capacity of a memory module is determined by the number of chips and the size of each chip. Most SDRAM and DDR RAM modules are configured with

8 or 16 chips. Each chip, typically, has a size (or density) of either 64 MB or 32 MB. Total capacities for modules can range from 128 MB to 8 GB.

The way a chip stores data is expressed as the depth of the chip by its width. For example, 64 x 8 means that the storage locations in the chip are organised

into 64 rows and 8 columns, with a total capacity of 512 MB, if there were 8 such chips on a module. The module would be 64 x 64 and have a capacity of

512 MB. X4 chips are cheaper than X8 or X16 but can cause problems with some motherboards, especially in high capacity modules (1 GB).

The number and layout of chips on a memory board does not, generally, affect

system performance, except when a dual channel motherboard is used. That being said, for optimum stability, use the same density (and brand) of memory

in all sockets, if available.

3.4.2.2 Memory banks

When memory is installed it must fill a bank, which is the amount of data the

memory controller expects to fetch. All current PC motherboards support a 64-bit data bus, matching the 64-bit data bus of DIMMs.

3.4.2.3 Single- and double-sided memory

Single-sided, or more precisely ‘single rank’, memory is a module that fills a

single bank (that is, the memory controller can access all of the memory chips on the module at the same time).

Double-sided, or ‘dual bank’ or ‘dual rank’, memory divides the memory chips

on a single module into two ‘ranks’ (the memory controller can access one rank or the other, not both simultaneously). This makes the memory lower in

cost and higher in density, however, it degrades performance slightly. There are also quad rank modules, though these are, usually, designed for server

hardware.

The memory controller on a motherboard will only be able to support a given

number of ranks. Consequently, DlMM slots may not always support dual rank modules or may only support one dual rank module (typically this must be

installed in the first slot), thus remember to read motherboard documentation carefully. In some instances, support for dual or quad rank memory may be

enabled through a BIOS update.



3.4.2.4 Dual channel memory

The increasing speed and architectural improvements of CPU technologies have led to memory becoming a bottleneck to system performance. To address this,

Intel and AMD developed a dual channel memory architecture for DDR and DDR2 RAM. Dual channel memory was originally used primarily on server

hardware but it is now also being commonly employed on desktop systems and laptops.

With a dual channel memory controller on the motherboard, there can be,

effectively, two pathways through the FSB, meaning that 128 bits of data can be transferred per ‘transaction’ rather than 64 bits (though, in most

configurations, they continue to operate as two independent 64-bit pathways).

Ordinary RAM modules are used, that is, there are no dual channel DDR memory modules.

Example

A dual channel motherboard might have four DIMM slots arranged in colour-coded pairs. Each pair represents one

channel and each slot represents one of the two sockets in each channel. The memory modules installed should be

identical in terms of speed, capacity, chip number, density and location. If only two slots are used, to enable dual

channel memory, the modules must be installed in socket 1 of each channel. You will need to consult the system

documentation carefully to identify the appropriate slots to use. For motherboards supporting Intel CPUs and some

AMD CPUs, the first sockets in both channels are slots 1

and 3. For most AMD CPU-based motherboards it would mean filling slots 1 and 2.

Adding an odd number of modules or adding mismatched DIMMs will cause a

system to operate in single channel mode. Dual Channel Mode may also need to be enabled via CMOS Setup.

Some of Intel’s CPUs and supporting chipsets have triple or quadruple channel

memory controllers; AMD is starting to release quadruple channel controllers. In these architectures, if the full complement of modules is not installed, the

system will revert to dual or single channel operation.



3.4.2.5 ECC memory

Motherboards used to use a simple error detection method, called ‘parity checking’. Each byte of data in memory is accompanied by a ninth bit. This bit

is set to 1 or 0 to make the total number of bits set to 1 in the byte (an odd or even number, depending on the type of parity checking being performed).

When the byte is read, its parity is checked to ensure that the parity value is

still odd or even, whatever the case may be. If this is not the same, a bit must have become corrupted.

System memory for most desktops is non-parity; that is, it does not perform

error checking. For systems that require a high level of reliability, such as

workstations and servers, ECC memory is available.

ECC memory is enhanced parity circuitry that can detect internal data errors and make corrections. ECC will detect and correct single bit errors and allow

for the system to continue functioning normally. It will also detect errors of 2, 3 or 4 bits but will not correct them; instead, it will generate an error message

and halt the system.

ECC memory has an extra chip and a 72-bit data bus, rather than 64-bit. The motherboard must support the use of ECC memory modules and the option to

use them must, typically, be enabled in CMOS Setup. ECC memory cannot be mixed with non-ECC modules.

An ECC DIMM will have an odd number of memory chips while on-parity DIMMs

will have an even number of memory chips.

3.4.2.6 Registered memory

Most SDRAM and DDR SDRAM is unbuffered. Registered memory has an extra

component that stores address information, taking some load off of the memory controller.

Registered memory is slightly slower but increases system stability when a

large amount of memory (2 GB or more) is installed. Most, but not all, ECC RAM is registered. Non-ECC registered chips are also available at higher cost

than unbuffered chips.

Registered RAM must be supported by the motherboard. Registered and unbuffered modules cannot be mixed.



3.4.3 Installing and upgrading memory

Adding or upgrading system memory is often the cheapest and simplest way of increasing system performance.

If the motherboard supports such but the system is not configured to use it,

enabling a dual channel configuration is the best way of extracting more performance from existing components. Increasing the bus speed would

require purchasing a new motherboard and memory modules (and possibly a

new CPU).

When purchasing a computer, it is a good idea to get the fastest memory bus that you can afford as this is the component that is most difficult to upgrade

later.

3.4.3.1 Memory compatibility issues

In terms of compatibility, always consult the motherboard user guide and consider the following general guidelines:

The DlMM format must match the motherboard (for example, you cannot

install DDR modules in DDR2 slots) Different capacity modules can be installed, with the exception of Rambus or

multichannel configurations. Most vendors recommend installing the largest

module in the lowest numbered slot Modules from different vendors can be mixed, though this may cause

problems with multichannel configurations For best performance, the modules should be the same speed as the

motherboard. Different speeds can be mixed but the system will only work at the speed of the lowest clocked module; this is, generally, not a good idea

For best performance and reliability, configure multichannel systems with identical memory modules for each channel

ECC memory cannot be mixed with non-parity memory and must be supported by the motherboard. Similarly, registered memory cannot be

mixed with unbuffered modules and must be supported by the motherboard Memory modules are quite easy to insert and remove (unless being within

the case makes them inaccessible). The key point here is to ensure that the memory is suitable for the system and in the correct configuration

3.4.3.2 Removing memory modules

In order to remove DIMMs, you must release the plastic or metal catches at either end. Once you have released the catches, you can remove the memory

module by hand (it should pop up out of the slot). Handle the module by the edges; avoid touching the chips.



CPU, memory and the chips on the motherboard are particularly sensitive to ESD. Ensure that you take antistatic precautions when handling and storing

components.

3.4.3.3 Installing memory modules

To install memory modules, follow the following procedure:

Locate a spare memory socket. Most memory sockets are numbered on the motherboard. This numbering may start at 0 or 1. Some motherboards allow

for these slots to be filled in any order, however, most require that you fill the slots from the lowest numbered slot upwards. Unused RIMM slots must

be filled with RIMM terminators. Refer to the motherboard documentation for

specific requirements Line up the memory card. There are notches on the bottom edge of a

memory card to ensure that such is inserted correctly. Check that the notches in the memory card are aligned correctly with the memory socket

before you attempt insertion Insert the memory card. DIMMs are pushed straight down into the socket.

The retaining clips at either end should move towards the centre until they lock into the notches at the side of the DIMM when the module is fully

inserted (Figure 47):

Figure 47 – Orientate the memory module so that the notches on the card and slot

match up, then push down so that the retaining clips click into place


Reboot the PC and watch the RAM count during startup to verify that the

memory has been recognised. From Windows, you can check the installed RAM by looking at System Properties or the System Information program



3.5 CPU

The CPU, or simply the ‘processor’, executes program instruction code, performs mathematical and logical calculations, and controls I/O functions. It

is commonly described as the ‘brains’ of a computer, in fact, it is better

thought of as a very efficient sorting office. The CPU itself cannot think but it can process simple instructions very, very quickly and efficiently. A computer

is, ultimately, only as ‘clever’ as its software.

PC processors are produced by Intel and other manufacturers who use the Intel instruction set and whose processors are, therefore, IBM PC (or X86)

compatible (currently only AMD falls into this category).

3.5.1 Overview of CPU

There have been numerous CPU architectures and within each a number of

different models. For each set of model there is a brand to position such within a particular market segment. The following sections will give you a brief

overview of the main ranges produced by Intel and AMD.

3.5.1.1 Intel CPU range

The Intel CPU range includes:

Core: this is Intel’s flagship desktop and mobile CPU series. The earliest models (Core Solo and Core Duo) were laptop-only chips. The Core 2

introduced desktop versions as well as 64-bit and multicore support. The current range is divided into Core i3, i5 and i7 brands, with the i7

representing the best performing models. The Core i-range has been based on three micro-architectures, code-named Nehalem, Sandy Bridge and Ivy

Bridge

Pentium: this used to be Intel’s premium 32-bit CPU brand and you may still find Pentium 4 computers in use. The Pentium brand has been reintroduced

to represent mid-range CPU models based on the Nehalem and Sandy Bridge micro-architectures

Celeron: this has long been Intel’s budget brand Atom: this is a relatively new (2008) brand designed for low power portable

devices (smartphones and tablets) Xeon: this brand is aimed at the server i-workstation market. Current Xeons

are often differentiated from their Core counterparts by supporting n-way multiprocessing, ECC memory as well as coming with larger caches



3.5.1.2 AMD CPU range

The AMD CPU range includes:

Athlon: this was AMD’s long-standing premium consumer brand. Modern Athlons start with the Athlon 64 and its FX (top-end) and X2 (dual core)

variants. With the reintroduction of the plain Athlon series and, subsequent, Athlon ll models, the brand has been repositioned for the mid-range market

Phenom: this replaced the Athlon as AMD’s premium CPU brand. The latest range is branded as Phenom ll

Sempron: this is AMD’s budget brand, positioned to compete with Intel’s Celeron

Turion: this brand is used for laptop processors

The brands mentioned above are likely to be phased out over the next few

years, with the following replacing them:

AMD Fusion (A series): this represents what AMD refers to as ‘accelerated’ Accelerated processing units (APUs): these combine a CPU and graphics

processing unit (GPU). At the time of writing this Study Guide, the lineup was divided into A4 (mid-range), A6 and AB (high performance)

AMD FX: this brand represents AMD’s pitch for the high-end ‘enthusiast’ segment

Opteron: this is AMD’s long-standing version of the Xeon brand, aimed at the server/workstation segment

3.5.1.3 ARM machines

ARM is another microprocessor vendor. While ARM does not have a presence in the desktop/laptop segment, its processors are widely used in the smartphone

and tablet segments.



3.5.2 CPU architecture

A CPU is designed to run software programs. When a software program runs (whether it be an OS, BIOS firmware, antivirus utility or word processing

application) it is assembled into instructions utilising the fundamental instruction set of the CPU and loaded into system memory. The CPU then

performs the following operations on said instructions (note that this overview is grossly simplified):

The control unit fetches the next instruction in sequence from system memory to the pipeline

The control unit decodes each instruction and either executes it itself or passes it to the arithmetic logic unit (ALU) or floating point unit (FPU) for

execution The result of the executed instruction is written back to a register or to

system memory. A register is a temporary storage area available to the different units within the CPU

Over the years, many different internal architectures have been developed to

optimise the process of fetch, decode, execute and write back, while retaining compatibility with the basic X86 instruction set, which defines a CPU as IBM PC

compatible.

3.5.2.1 Hyper threading

One way of making instruction execution more efficient is to improve the way

in which the pipeline works. The basic approach is to do the most amount of work possible in a single clock cycle (multitasking). There are various ways to

achieve this goal.

CPUs process multiple instructions at the same time (for example, while one instruction is fetched, another is being decoded, another is being executed and

another is being written back to memory). This is referred to as a ‘superscalar architecture’ as multiple execution units are required. Superscalar

architectures feature longer pipelines, with multiple stages but shorter actions (micro-ops) at each stage, referred to as ‘super-pipelining’.

The original Pentium had a five-stage pipeline; by contrast, the Pentium 4 has

up to 31 stages (NetBurst architecture). NetBurst actually proved relatively

inefficient in terms of power and thermal performance, so Intel reverted to a modified form of the P6 architecture that it used in Pentium IIs and IIIs for its

Core brand CPUs (with around 14 stages).



Another approach (introduced on some Pentium 4 models) is simultaneous multithreading (SMT), called ‘hyper threading’ by Intel.

A thread is a stream of instructions generated by a software application. Most

applications run a single process in a single thread; software that runs multiple parallel threads within a process is said to be multithreaded. SMT allows for

the threads to run through the CPU at the same time. It duplicates many of the registers of the CPU and this, in turn, reduces the amount of ‘idle time’ the

CPU spends waiting for new instructions to process. To the OS, it seems as though there are two CPUs installed.

The main drawback of SMT is that it works best with multithreaded software.

As this type of software is more difficult to design, it tends to be restricted to

programs designed to run on servers. Desktop application software thus cannot often take full advantage.

Hyper threading was implemented on Premium models in the Pentium 4 range

but was not used on the Core 2 chips. It has been reintroduced as a feature of Core i7 and Atom processors from Intel.

3.5.2.2 Microcode improvements

Another approach to improving CPU efficiency is to extend the basic

instructions set. Many applications, such as games, video decompression and speech recognition, make repetitive use of the same instructions with different

data. Intel and AMD both introduced instructions set extensions to support this kind of single instruction, multiple data (SIMD) programming.

3.5.2.3 Multiprocessing and multicore

Yet another approach to making a computer system faster is to use two or more physical CPUs, referred to as ‘symmetric multiprocessing’ (SMP). SMP

can make efficient use of available processing resources to run application processes on whichever CPU is ‘available’. This approach is not dependent on

software applications being multithreaded to deliver performance benefits. Traditionally, SMP was provided by physically installing two or more CPUs in a

multisocket motherboard. Obviously, this adds significantly to the cost, thus it is only implemented on servers and high-end workstations.

Improvements in CPU manufacturing techniques have led to another solution:

dual core CPUs or chip-level multiprocessing (CMP). A dual core CPU is essentially two processors combined on the same die. The market has quickly

moved beyond dual core CPUs to multicore packages with three, four or eight

processors. For desktop computing, however, the performance benefits of multicore are unlikely to increase dramatically unless backed up by improved

software design.



Dual core is not quite the same as SMP and software has to be specially written or updated to take advantage of the architecture. Windows XP service

pack (SP) 2, Windows Vista and Windows 7 provide full support.

Table 7 provides some examples of multicore CPUs:

Table 7 – Multicore CPU examples

Core Intel AMD

2 Core Duo, Core 2 Duo, Core i3, Core

i5, Xeon, Celeron and Pentium D

X2 models of Athlon 64, Sempron, Turion

64, Phenom, Phenom II and Opteron

3 -- X3 models of Athlon II, Phenom and

Phenom II

4 Core 2 Quad, Core i5, Core i7 and

Xeon

X4 models of Athlon II, Phenom, Phenom

II and Opteron

6 -- Phenom II and Opteron

8+ Xeon Opteron


3.5.2.4 Instruction set architecture (32-bit vs 64-bit)

The instruction set used by IBM PC compatible CPUs is X8642 or IA-32 (Intel architecture). As described, this has been extended with SIMD instructions and

the way in which such are processed internally has been modified and

optimised by various different CPU architectures; otherwise, the same platform has been used for the last 30 years.

Up until a few years ago, CPUs were designed to run 32-bit code. This means

that each instruction can be up to 32 bits in length. A 32-bit CPU’s general purpose (GP) registers are also 32 bits wide. However, since 2004, most

desktop CPUs (and from 2006, most laptop CPUs) released to the market have been capable of running 64-bit code.

Intel first developed a 64-bit instruction set for its Itanium server CPU platform

in 2001. This platform, however, has never gained acceptance in the PC market. AMD’s 64-bit instruction set (AMD64) has proven more popular and

was adopted by Intel for its 64-bit desktop and mobile line. Intel refers to it as ‘EM64T’ or ‘Intel 64’. The same instruction set is also called ‘X86-64’ or ‘X64’.

The utilisation of 64-bit CPU features by installing 64-bit OSs took some time to grow, principally because of the lack of 64-bit drivers for peripheral devices.

At this point, it is estimated that about half of the Windows install base is 64-bit.



3.5.2.5 Cache

A computer stores data for programs and files currently open in system memory. The CPU has registers to store instructions and data that it is

processing. Instructions are moved in and out of these registers to system memory.

Cache is a small block of high speed memory that enhances performance by

preloading (caching) code and data from relatively slow system memory and passing it to the CPU on demand. Essentially, cache stores instructions and

data that the CPU uses regularly.

Complex superscalar architecture depends heavily on routines that predict

which instructions will be used most as well as in which sequence. If these instructions are readily available to the control unit, overall throughput is

greatly enhanced.

Cache is designed in multiple levels. Level 1 cache is ‘closest’ to the CPU and supports the fastest access. Level 2 cache is larger and a bit slower while Level

3 cache, if used, is larger and possibly a bit slower still. Level 1 cache is a small block (typically around 64 KB) and Level 2 cache is larger (between 512

KB and 2 MB).

Cache design becomes even more important with multicore CPUs as multiple components are contending for the use of a single resource (system memory).

At each level, cache can either be discrete (available to one core only) or shared (available to all cores), depending on the processor model.

3.5.2.6 Addressing

The system bus between the CPU and memory consists of data and address buses. The width of the data bus (64-bit on all current CPUs) determines how

much data can be transferred per clock cycle; the width of the address bus determines how many memory locations the PC can access.

The address bus for most 32-bit CPUs is either 32 or 36 bits wide. A 32-bit

address bus can access a 4 GB address space; a 36-bit expands that to 64 GB. In theory, a 64-bit CPU could implement a 64-bit address space. In practice,

the current generation of X64 CPUs are ‘restricted’ to 40-bit address spaces (1 TB) to reduce the complexity in remaining compatible with 32-bit software.



3.5.3 Other CPU features

Apart from the architectural features discussed, the speed at which a CPU runs is, generally, seen as a key performance indicator. This is certainly the time to

compare CPUs with the same architecture, however, it is not necessarily the case otherwise. For example, Intel Core 2 CPUs run slower than Pentium 4s

but deliver better performance.

3.5.3.1 Clock speed and overclocking

The core clock speed is the speed at which a CPU runs internal processes and

accesses Level 1 and Level 2 cache. The FSB speed is the interface between the CPU and system memory.

Overclocking increases the clock speed, which, in turn, improves performance.

When manufacturers release a new chip, they set an optimum clock speed based on system testing. This clock speed will be set at a level where damage

to the chip is not likely to occur during normal operation.

Increasing this speed (overclocking) is done via CMOS Setup by adjusting the CPU speed or advanced chipset features properties. Increasing the clock speed

requires more power and generates more heat. Therefore, an overclocked system must have a suitable power supply and sufficient cooling. The

operating environment (the warmth of the room and dust) must also be

carefully controlled.

Overclocking is, generally, performed by hobbyists and game enthusiasts but it is also a means of building a PC more cheaply by specifying lower cost

components and then boosting their performance.

Without cooling, overclocking increases the risk of thermal damage to components and may increase the frequency of system lockups. It also voids

the warranty. Vendors, generally, try to prevent overclocking by disabling custom settings in a computer’s CMOS Setup program.

A CPU may also run at a lower actual speed than it is capable of if it is put in

Power Saving Mode.

3.5.3.2 Power management (throttling)

Rising energy costs and environmental legislation are placing power efficiency

at the top of the agenda for buyers. In terms of CPU performance, more speed means greater power consumption and heat production. To deal with such,

CPUs can implement power management to enter lower power states, referred to as ‘throttling’.



Inlet chips implement throttling using speed step technology. The original version simply allowed for high and low frequency modes. Enhanced speed

step allows a CPU to step up or down through a range of voltages.

Another aspect of power management is CPU protection. If a processor runs too hot, the system can become unstable or damage can occur. Some Intel

CPUs provide a Thermal Monitor (TM) Mode, triggered by a temperature gauge (the activation point depends on the processor but tends to be around 50°C to

65°C). Intel CPUs work in one of two modes, depending on the age of the model:

1. TM1 (speed step): the CPU inserts idle cycles between instructions

(implemented on early Pentium 4 models)

2. TM2 (enhanced speed step): the CPU lowers the actual clock speed (used on later P45 and current mobile and desktop CPUs)

Power management on AMD CPUs is referred to as ‘PowerNow’ (mobile CPUs)

or ‘cool ’n’ quiet’ (desktop CPUs).

3.5.3.3 Malware protection

Computer viruses and other malware can use various techniques to infect a computer. One is a so-called buffer overflow attack, where the virus ‘tricks’

another program into executing it as the program thinks that it is just processing some data.

CPUs and OSs supporting AMD’s no execute (NX) technology are more resilient

against attack; they prevent areas in memory (marked for data storage) from

executing code (running a new program). Intel calls this feature ‘execute disable’ (XD); Windows refers to it as ‘data execution prevention’ (DEP).

3.6 Disassembling a PC PC components that are easily user replaceable or upgradeable are referred to

as ‘field replaceable units’ (FRU). Owing to economic factors, most PC units are

not worth repairing, instead they are simply replaced with a new unit (‘swapped out’).



Before you start to disassemble a PC you should consider doing the following:

Make a backup of the HDDs to protect important data Create a clean work environment with plenty of working space where you

can set the PC at a comfortable height Gather all the necessary tools and equipment. A notepad and pen may be

useful for drawing diagrams and making notes. A digital camera could also be useful for recording the layout of components

Ensure that all devices are powered off and disconnected from mains before removing them

Take ESD precautions to minimise the chance of damaging static sensitive components. Always place static sensitive equipment, such as processors

and memory, in antistatic bags

3.6.1 Parts of a PC case A PC case has a cover, which is removed by either undoing the screws at the

back or by pressing clips together to release such. Cases based on a slim-line design have a hinged cover that releases to allow access to the motherboard.

Some cases feature tool-free access (that is, they are secured only by clips)

while others use proprietary screw fittings (to prevent unauthorised access to internal components).

The front panel provides access to the removable media drives, a power on/off switch, reset switch and LEDs (to indicate drive operation). The front cover can

be removed but may require the side panel to be removed first in order to access the screws/clips that secure it.

The rear panel has slots through which adapter card ports appear. These slots

should either be covered by an adapter card or metal strip, known as a ‘blanking plate’. Uncovered slots can disrupt proper air flow around PC

components, which could cause overheating as well as an increase in the amount of dust in the system.

There are also slots through which the motherboard ports appear, such as

parallel and serial ports. The rear panel, further, provides access to the PSU sockets. The PSU has a fan exhaust; care should be taken that such is not

obstructed as this will adversely affect cooling.



3.6.2 Removing a system case lid

To remove a system case lid, follow the following procedure:

With the power cable removed, press and hold the power button for a few seconds. This should ensure that the circuits within the computer are

completely de-energised Find the screws that secure the lid to the system case and unscrew them.

Some system case lids have clips instead of, or as well as, screws.

Remember to keep the screws in a secure place The main panel is, usually, opposite the I/O ports. Once the system case lid

is removed, you can access the internal devices and begin to remove them. Other parts of the case, such as the front panel or second side panel, are,

usually, removed using clips (accessible once the main side panel has been removed)

3.7 Installing Windows

3.7.1 Overview of OS installation

There are two main approaches to installing Windows, namely:

1. Clean installation: this refers to an installation on a new computer or completely replacing the software on an old computer

2. Upgrade: this refers to an installation on top of an existing version of Windows; this route retains applications, user settings and data files

A clean installation is, generally, seen as more reliable than an upgrade. In a corporate network environment, installations are performed using images (a

template containing the OS and other related software) so that machines contain a consistent set of software and configuration options. PC vendors also

use images to install new equipment.

Upgrades are, generally, designed for home users. Upgrade software can be purchased at a discount.

A clean installation should be carefully planned; it will consist of the following

phases:

Verify hardware compatibility (are the core components of the computer sufficient to run the OS and do the peripheral devices have drivers suitable

for use with the OS)

Select an installation method Back up any existing user data and/or settings

Prepare the HDD and copy the setup files to the target Configure the installation options

Verify the installation (check logs and complete tests to confirm that the installation was successful)



3.7.1.1 Hardware compatibility

The first step in checking hardware compatibility is to verify that the system exceeds the recommended requirements. The minimum requirements will,

usually, not deliver adequate performance.

Ensure that you know the system requirements and limitations for the various versions and editions of Windows. Also verify that the peripheral devices and

expansion cards will work under the OS. Effectively this means: has the manufacturer released a stable driver for the OS?

Unsupported hardware can cause problems during the setup process; these

should be physically uninstalled from the PC.

3.7.1.2 Data and settings backup

This is clearly not necessary if installing a new computer, however, it is a vital

step if you are updating (rather than upgrading) an existing installation.

While it takes more time, performance and reliability can be improved by performing a clean installation. The general process to follow is:

Back up all data from the existing target system. You can use the backup

program supplied by Windows, a third-party backup program, the Flies and Settings Transfer Wizard, Windows Easy Transfer or the User State Migration

tool Install the new OS, overwriting the existing target (optionally reconfigure

the disk partition and file system structure)

Reinstall software applications and utilities Restore data from the previous system

3.7.2 Installation boot methods The installation boot method refers to the way in which an installation program

and settings are loaded onto a PC. There are a number of ways to install Windows; you can perform a cross-network installation, installation via local

CD/DVD or a deployment.

3.7.2.1 CD/DVD

Most manual installations are run by booting from a CD or DVD. You can also

run a clean installation or an upgrade from an existing Windows installation.



3.7.2.2 USB

A problem with disc-based installations is that the setup disc quickly becomes out-of-date and post-installation tasks for installing drivers, updates and SPs

can take longer than the original installation. One way around this is to build slipstreamed media, with all the various patches and drivers already applied.

The media could be CD, DVD or USB (if the computer supports booting from USB).

3.7.2.3 Pre-boot execution environment (PXE)

A remote network installation means connecting to a shared folder containing

the installation files (which could be slipstreamed). The target PC must have a

usable partition on the HDD in which to store temporary files.

3.7.2.4 Image deployment

Any installation involving more than a few PCs makes using imaging technology worthwhile. An image of an existing installation stored in one file is

created. Such can contain the base OS, configuration settings, SPs, updates, application software and whatever else is required. An image can be stored on

DVD or USB or it can be accessed over a network.

An attended installation is quite time consuming as you need to monitor the setup program and input information at various points. To simplify this

process, Windows supports the use of answer files, allowing for full or partial unattended installations. Creating and configuring answer files is done using

Setup Manager.

3.7.2.5 Factory recovery partition

A recovery disc or factory recovery partition (also called a ‘rescue disc’) is a

tool used by original equipment manufacturers (OEMs) to restore the OS environment to the same state that it was in while being shipped. The

disc/recovery partition is used to boot the system, then a simple wizard-driven process replaces the damaged installation with an image stored on a separate

partition on the HDD. In the case of a recovery partition, this is, usually, configured to be hidden from the user. The recovery process can be started by

pressing a key during startup (<F11> or <Ctrl>+<F11> are often used; a message is, usually, shown onscreen).

OEM media will not, usually, recover user data, settings or applications;

everything gets set back to the state in which the PC was shipped from the

factory. User data should be recovered from backup, which obviously has to be made before the computer becomes unbootable.



The advantages of using a recovery partition are that less time is required to rebuild the machine and, from a technical support point of view, recovery is

much easier for end users than reinstalling Windows. The main disadvantage with OEM recovery media is that the tool only works if the original HDD is still

installed in the machine; the recovery media will not include patches or SPs applied between the shipping and recovery dates.

3.7.2.6 Repair installation

An ‘in-place upgrade’ repair installation is a ‘last gasp’ method of restoring a

Windows installation that will not boot. The installation process is run over the top of the existing installation. In theory, this route can preserve some

settings, application software installations and data files while restoring system

files. Repair installations are unlikely to work and there are, usually, better tools available to troubleshoot a system that will not boot (Figure 48):

Figure 48 – Performing a repair installation in Windows XP


3.7.2.7 Multiboot

If a user needs multiple OSs, such can be set up on the same computer in a

multiboot environment. Most OSs can be run in this way, with the following caveats:

Each OS should be installed on a separate partition

The system partition must be accessible to each OS (that is, typically, it must be formatted using FAT)

The system partition is where the boot files are and the boot partition is where the OS is installed.



New OSs should not overwrite the boot loader. The general principle is to install the older OS first; older OSs are less likely to recognise a multiboot

environment. Alternatively, the boot loader may need to be reconfigured manually following the installation of an OS.

3.7.2.8 Preparing a HDD

Windows must be installed on a partition of a suitable size, formatted with an

appropriate file system. The boot and system partitions cannot be changed (except by using third-party tools) so it is important to plan this step in

accordance with the way in which the computer will be used, namely:

Will the computer have multiple OSs installed (mum-boot)? If so, it is best

practice to create a partition for each OS Will partitioning achieve better performance? A disk of 80 GB+ may benefit

from being partitioned but, in other cases, the performance benefits may be minimal

Does the boot partition have spare capacity for growth? Running out of space will cause serious problems, thus you need to leave sufficient

overhead. Windows Vista and Windows 7 must be installed on a boot partition formatted with NTFS

Is some sort of hardware RAID being used? If so, the RAID utility must be used to configure the RAID level and to create volumes before the OS can be

installed. A RAID configuration utility is invoked by pressing a key combination, such as <Ctrl>+<F>, during startup (when the RAID

firmware BIOS is being processed)

There are various tools available to partition disks (including fdisk supplied

with Windows). The Windows Setup program includes a Text Mode disk management program that should be suitable for most users.



3.7.2.9 Loading a HDD

In order to manage the HDD, the setup program must have an appropriate driver for it; most of the time the setup media will include a suitable driver.

In Windows XP, you have a few seconds to press <F6> when the setup

program first loads (Figure 49):

Figure 49 – Loading alternate third-party drivers in Windows XP


In Windows Vista and Windows 7, you can click the Load Driver button on the

Disk Configuration dialog box (Figure 50):

Figure 50 – Windows 7 setup options




3.7.3 Windows setup

Windows Vista and Windows 7 have a graphics user interface (GUI) to create and modify partitions. By default, Windows 7 creates separate system and

boot partitions when installed on an unpartitioned disk. The small (100 MB) system partition (system reserved) is used to store the Boot Manager and Boot

Configuration Database; it can also be used for BitLocker drive encryption. The partition is not allocated a drive letter.

The Windows XP tool is part of Text Mode setup but is still simple to use: once you have selected (or created) your partition, you can create more partitions

using the Disk Management tool (assuming that you have free unpartitioned space available on the disk) (Figure 51):

Figure 51 – Creating a partition using the Windows XP Setup program




3.7.3.1 Choosing a file system

Another choice is whether to use NTFS or FAT/FAT32 for the boot and system partitions (Figure 52). Choose NTFS unless there are good reasons for using

FAT (compatibility in a multiboot environment).

Figure 52 – Formatting a partition using the Windows XP Setup program


In Windows XP, any of these file systems will support the boot and system

partitions. Note, however, that there are some significant differences. Windows Vista and Windows 7 only support the installation of a NTFS boot partition,

though they can read and write to FAT/FAT32 drives.

You also have the choice of either performing a quick or full format. A full

format checks the disk for bad sectors; selecting the quick option skips this check.

3.7.3.2 Completing an attended installation

When performing an attended installation, you need to manually configure

setup at various points in the process. Windows XP Setup requires that you return to check the program at regular intervals; Windows Vista and Windows

7 Setup are streamlined with all the configuration options at the beginning and end of the process.



3.7.4 Windows XP setup

In Windows XP, the first phase of set up (\mnnt.exe) is Text Mode, where you follow prompts to accept the End User Licence Agreement and to configure the

disk (as discussed). The system then reboots into a GUI setup mode where you make various additional choices, including configuring regional settings

(Figure 53), registering the product, entering the product licence key and choosing a computer name as well as a password for the default administrator

account (Figure 54):

Figure 53 – Configuring regional and language settings in Windows XP Setup


Figure 54 – Choosing a computer name and setting a password for the default

administrator account in Windows XP Setup




3.7.4.1 Joining a network

During installation, the machine should be given a 15 character name that is unique within the workgroup or domain. The machine name should not contain

spaces or punctuation (other than hyphens). To join a network, you must install appropriate protocol and client software as well as configure such to

obtain a valid network address.

To join a workgroup, simply enter the workgroup name when prompted. However, to join a domain, you will need the following:

A computer account that is already configured in that domain or account

credentials that will enable you to add your machine to the domain during

installation A Windows server domain controller that is online and accessible during

installation A Domain Name System (DNS) server that is online and accessible during

installation to enable you to locate a domain controller

3.7.4.2 Completing Windows XP setup

Following network configuration, Windows XP Setup will proceed to install Windows and detect and configure plug-and-play devices.

Windows will now load and you will be prompted to log on. Any hardware

devices not installed during setup will be detected and you will be prompted to select a driver.

When you reach this point, it is a good sign that the installation has succeeded. You might want to verify the log files, check the Device Manager to confirm all

hardware has been recognised and test each hardware device to verify functionality. You can use Add or Remove Program (in Control Panel) to install

any optional Windows components.

3.7.4.3 Running Windows XP for the first time

When you run Windows XP for the first time, a Welcome to Windows screen will display. This wizard-driven component will guide you through the final

phases of system configuration.



During this process, you might be asked to:

Configure your Internet connection: details will include proxy settings, etc. Your Internet connection is needed for product activation but you can

configure this later. (An unpatched installation of Windows is very vulnerable to malware, specifically the Blaster and Sasser worms. If possible, obtain

and install SPs on CD before connecting to the Internet. If using SP2 media, additional steps will prompt you to configure automatic updates and enable

the firewall before proceeding) Activate Windows: product activation guards against software piracy (Figure

55). If the OS is not activated, it will cease to operate after 30 days. This activation can be completed via the web or over the telephone

Figure 55 – Product activation


Define computer users: you must define at least one user. Each user added here is configured with local administrator privileges

3.7.5 Windows Vista and Windows 7 setup The installation of Windows Vista and Windows 7 covers broadly the same

steps but in a slightly more efficient order; this reduces the amount of time that you will have to monitor the process during an attended installation. Also,

the whole installation process takes place within a GUI. The process setup.exe

replaces the winnt.exe process used by Windows XP.



The first step in a Windows Vista/Windows 7 installation is to choose the regional format settings and keyboard type (Figure 56):

Figure 56 – Choosing regional options in Windows 7 Setup


Having done so, you can proceed by accepting the End User Licence Agreement, choosing an installation type (upgrade or custom (clean

installation)) and partitioning and formatting the disk. Setup then proceeds

without requiring intervention.

Note that Windows Vista and Windows 7 do not support joining a domain during an attended installation. A computer can be joined by reconfiguring

system properties or it can be joined during an unattended installation by using an answer file.



When the system reboots, you can complete the setup configuration by doing the following:

Choose a username and password: this account will be the local

administrator account, so choose a strong password Enter the product key: if you do not enter the product key, choose the

edition of Windows that you are installing. You must enter a key and activate Windows within 30 days

Configure automatic updates (Figure 57):

Figure 57 – Choosing update settings in Windows 7 Setup


Check that the date and time settings are correct and configure the time zone

Set the computer’s network location: this configures default firewall settings

Concluding remarks In this unit, we introduced health and safety regulations that should be

complied with when it comes to computer systems. We also explored the installation and disassembly of main computer components. Windows XP, Vista

and 7 installation setups were illustrated.

In the next unit, we will investigate computer system configuration.



Self-assessment

Test your knowledge

1. In a computer environment, how do you protect against electric shock?

2. In a computer environment, how do you protect against electrostatic electricity?

3. In a computer environment, how do you protect against overloading power

points?

4. In a computer environment, how do you protect against fire hazards?

5. Briefly discuss RAM vs ROM.

6. Explain the use of RAID.

Unit 4 – System Configuration Page 101


Unit 4: System Configuration


Learning outcomes



Assessment criteria AC2.2 Evaluate the suitability of a computer system

design specification AC3.1 Build and configure a computer system to meet a


Learning objectives


Use CMOS Setup to configure BIOS settings Know how to use OS independent diagnostic programs

Introduction

In the previous unit, you learnt how to install system components and OSs.

In this unit, you will learn how to use CMOS Setup to check system components installed as well as their working status. We will also focus on how

to configure computer systems to match user specifications for a given type of computer system.



4.1 CMOS Setup

You can, normally, access CMOS Setup with a keystroke during the boot process. The key combination used will vary from system to system; typical

examples are <Esc>, <Del>, <F1>, <F2> or <F10>. A PC’s documentation

will explain how to access CMOS Setup; often a message with the required key is displayed when booting a PC. You can navigate using the keyboard keys and

pressing <Esc> to, generally, return to a previous screen.

4.1.1 BIOS component information

CMOS Setup will contain information about core components, such as the CPU, chipset, RAM, HDDs, optical drives and battery (laptop).

4.1.1.1 Overclocking

On some systems, you may be able to configure settings for CPU voltage and memory clock frequency. You can use these settings to overclock the CPU,

system memory or GPU to make such run faster than the manufacturer intended. Overclocking increases the amount of heat generated by the CPU

and can thus damage such. Incorrect settings can also make a system unstable. Generally, it is best to let the system configure these settings

automatically.

Most OEMs disable overclocking through their versions of CMOS Setup. This feature is, generally, only available with retail motherboards and components.

4.1.1.2 CPU features

Some CPU features can be configured, such as the number of cores, cache and

power performance (speed step).

4.1.1.3 Power management

If the BIOS supports advanced configuration and power management interface

(ACPI) there may also be an option to enable/disable power management. Power management enables features, such as soft power on/off (enabling the

Windows shut down routine to power off the computer), power saving modes, hibernation, etc. This option should, normally, be enabled. An interesting

feature is Auto-on Mode, which activates the computer automatically at a set time each day. On a laptop there may be options to check battery performance

and configure default LCD brightness.



4.1.1.4 Health check features

The BIOS may have an option for enabling/disabling PC health check features, such as temperature monitoring, checking fan speeds or displaying problem

alerts.

4.1.1.5 Date, time and daylight savings

Often referred to as the ‘real time’, this is simply the calendar date and time. A PC’s clock can be automatically adjusted back or forward one hour, as

appropriate, within the time zone under Windows. If the clock starts to lose the correct date or time, the CMOS battery could be failing.

4.1.1.6 Configuring the boot sequence

One of the most important parameters in CMOS Setup is the boot sequence or boot device priority; this defines the sequence in which the BIOS searches

devices for a boot loader. You will, usually, be able to set three or four options in priority order. The typical choices are HDDs, optical drives, USB and

network.

4.1.1.7 Configuring onboard devices

There will be options for enabling, disabling and/or configuring controllers and adapters on the motherboard. This will certainly include storage adapters

(floppy and PATA/SATA) and possibly features, such as serial and parallel ports, USB, Firewire, network adapters, modems, and graphics and sound

cards.



4.1.2 BIOS security

Different BIOS software will provide different support for BIOS passwords. There are, usually, at least two passwords (some systems may allow for

more):

Supervisor/administrator password: this protects access to CMOS Setup User password: this locks access to the whole computer. This is a very

secure way of protecting an entire PC as nothing can be done until the POST

has taken place. The only real way of getting around this would be to open the PC and reset the CMOS memory, which is not easy to do

Drive locks: there are, generally, three options for securing access to a disk specifically (rather than to the PC in general), namely:

1. Configure and store the password in PC firmware: this means that the disk is unusable except with the designated computer

2. Store the password in disk firmware: this is configured in conjunction with a compatible PC BIOS and means that the disk is transferable

between computers with a compatible BIOS 3. Use full disk encryption to encode the contents of the drive as well as

password protect such: the selected password is used as the basis of the encryption key. Again, this requires a HDD and BIOS compatible with the

same full disk encryption product

4.2 Custom configuration

4.2.1 Configuring computers for business use

4.2.1.1 Standard clients

A standard client (often described as ‘thick’ to distinguish it from a ‘thin’ client) is an ordinary office PC. It will be used to run locally installed desktop

applications, such as Microsoft Office (word processor, spreadsheets and presentations) as well as line of business software, e-mail, calendaring, contact

management and a web browser.

When configuring a standard client, it is important to pay attention to the recommended Windows system and software applications requirements.

Specifying the minimum Windows requirements is likely to lead to poor performance.



4.2.1.2 Thin clients

A thin client is a PC designed to act as an interface with applications that run on a network server. The client may be interfacing with particular software

applications or with a whole Windows desktop (virtual desktop infrastructure (VDl)). In this scenario, the only really important performance criterion is the

network link. The client PC does no application processing; it just transfers mouse and keyboard input to the server and processes video and audio output

coming back. The client will have to meet the minimum requirements for installing Windows.

4.2.1.3 Workstations

The term ‘workstation’ is sometimes used to describe a computer that runs more demanding applications than standard office suites.

Programming, development and virtualisation

A workstation used to develop software or games will run one or more rapid

application development (RAD) environments. It may also run a local database server application for testing. Consequently, these workstations require less

CPU and mass storage but adequate system memory.

Development work is also likely to require virtualisation, so that the developer has access to multiple OS environments for testing. Virtualisation requires a

large amount of system memory (a Windows Guest 05 would, typically, need 1 to 2 GB for average performance) and a fast and large disk sub-system. It

would also benefit from multiple CPU cores and multichannel memory.

Graphics, computer aided design (CAD) and computer aided

manufacturing (CAM)

A workstation used for different types of design will have to support applications with high CPU, GPU and memory requirements. Typical design

applications include:

Image editing and illustration tools Desktop publishing (DTP) and web design

CAD CAM



Multimedia development

A workstation used to edit audio/visual files, create animations or produce music will have high performance requirements. Again, it is important not to

overlook the disk sub-system, which can become a performance bottleneck as media files will often have to be streamed from the disk. Workstations will,

generally, need 10K or 15K disks to perform well. Multimedia files are also extremely large thus the disk sub-system will have to be high capacity. These

workstations require specialist adapters to capture audio and video from a variety of sources.

Dual monitors

With all types of workstation, screen ‘real estate’ is often at a premium; this means that they are often provisioned with two or more monitors.

RAID

As workstations are used to process critical data, where losing even an hour’s

work might represent a huge loss to the business, most of them will be configured with RAID to provide protection against disk failure.

4.2.2 Configuring computers for home use

When not used solely for homework and web browsing, home computers are often specified as ‘media centres’, ‘home theatres’ or ‘gaming rigs’.

4.2.2.1 Home theatre PCs (HTPCs)

A HTPC can be used instead of consumer appliances, such as a personal video

recorder (PVR) to watch and record television broadcasts and play movies and music. Such a PC will need to be equipped with an appropriate television tuner

card to process the incoming television signal (broadcast, cable or satellite) and, usually, comes with a remote control and peripherals, such as a wireless

mouse and keyboard.

4.2.2.2 Home server PCs and NAS

A home server PC is either a HTPC, with a slightly expanded role, or a

repurposed desktop or low-end PC server, used primarily for file storage and printer sharing. Such PCs do not need to be particularly powerful in terms of

CPU and memory but they will need a good network link. Most would also be configured with RAID to reduce the risk of losing valuable movie and audio files

(there must still be a backup system in place to protect against theft or fire).



There are also purpose-built devices to fill a home server role. A NAS appliance is a hard drive or RAID array with a cutdown server board, usually running

some form of Linux, that provides network access, various file sharing protocols and a web management interface. Such an appliance is accessed

over a network using either a wired Ethernet port or Wi-Fi.

In addition to sharing the disk resource, a NAS box will, usually, be able to share a printer. It will also be able to make files available over the Internet

using Hypertext Transfer Protocol (HTTP) or File Transfer Protocol (FTP). Care needs to be taken to secure the device and the router/firewall if this is to be

the case. Some NAS devices and home server PCs running Windows Home Server Edition can stream media files to wireless speakers or to a television (or

various other types of media player). A streaming media server will have

higher CPU demand, memory and bandwidth than an ordinary server.

4.2.2.3 Gaming PCs

A PC built for gaming is almost always based around the latest graphics adapter technology. Of course, the latest games tend to make the latest

graphics technology obsolete within a few months of release so upgrade potential is a key characteristic of these systems.

Gaming PCs will share some of the traits of a HTPC, such as surround sound

audio and a high quality display. There are also gaming oriented peripherals, such as keyboards and mouses. Many games also benefit from headsets so

that players can bark instructions at one another as they eliminate enemies over the Internet.

The addictive nature of PC games means that processors are very highly utilised (or ‘thrashed’) for considerable periods of time. Some gamers are also

fond of overclocking components to obtain better performance. All of this means that a gaming PC will generate more heat than most other types of

computer. It is not unusual for them to use more powerful fans or liquid cooling.

Concluding remarks

When configuring a PC it is important to pay attention to the recommended Windows system and software applications requirements for both business and

home environments. Different types of computer design will have to support applications with high CPU and memory capabilities.



Self-assessment

Test your knowledge

1. Define a thin client, standard client, overclocking and BIOS.

2. Briefly discuss the differences between home and business computer configuration.

Unit 5 – System Testing Page 109


Unit 5: System Testing


Learning outcome


Assessment criteria

AC3.1 Build and configure a computer system to meet a design specification

AC3.2 Test and document a computer system

Learning objectives


Diagnose possible hardware errors from basic symptoms Troubleshoot power and POST problems

Diagnose system component errors

Introduction In the previous unit, you learnt about how to configure computer systems after

installing system components to meet user specification requirements.

In this unit, you will learn about common computer system hardware problems and their symptoms. We will also discuss how to troubleshoot using POST as

well as how to troubleshoot components.



5.1 Troubleshooting hardware

There are several externally observable symptoms that may help you to diagnose hardware problems without having to open the computer chassis.

5.1.1 Indicator lights

Most devices have a status LED to indicate that such is receiving power/switched on. Some devices may have additional status indicators or

show other functions.

Example A HDD LED shows activity; normally this should only flicker

periodically. If the HDD LED is solid for extended periods it

may indicate a problem, especially if the PC is not doing any obvious processing.

Similarly, network adapters often have LEDs to indicate the connection speed

and activity on a network.

5.1.2 Alerts Most PC systems now have good internal monitoring systems, such as internal

thermometers. When these systems detect problems, they can display an administrative alert either on the local system or to some sort of network

management system. The OS may also be able to detect some kinds of hardware failure and display an appropriate alert.

5.1.3 Overheating

Excessive heat damages the sensitive circuitry of a computer very easily. If a system feels hot to the touch you should check that the fans are operating and

not clogged by dirt or dust. Unusual odours, such as a burning smell or smoke, will almost always indicate that something is overheating.

5.1.4 Loud noises Loud or unusual noises can often indicate that a device, such as a fan or HDD,

is failing. You need to distinguish between ‘healthy’ and ‘unhealthy’ noises.



Example A HDD may make a certain ‘whirring whine’ when first

spinning up and a ‘chattering’ noise when data is being written; clicking, squealing, loud noises or continual noises

may, however, indicate a problem.

5.1.5 Visible damage If a system has had liquid spilled on it or if fans or the keyboard are clogged by

dust or dirt, there may be visible signs of such.

5.2 Troubleshooting power problems PC components need a constant, stable supply of power to run. If a computer

will not start, it is likely be to a power problem. If a PC suddenly turns off or restarts, a power problem is also likely.

During the normal course of operation, the CPU converts the alternative

current (AC) mains supply to direct current (DC) voltage. DC voltage is used to power the internal drives and motherboard components. When the PSU is sure

that it is providing a stable supply, it sends a power good signal to the CPU.

The CPU then begins to run POST.

5.2.1 No power

If none of the LEDs on the front panel of the system case are lit up and you cannot hear fans or HDDs spinning, the computer is not getting power. This is

likely to be a fault in the PSU, incoming mains electricity supply, power cables/connectors or fuses. To isolate the cause, try the following:

Check that other equipment in the area is working; there may be a blackout

Check that the PSU cabling is connected to the PC and wall socket and that

all switches are in the ‘on’ position Try another power cable; there may be a problem with the plug or fuse.

Check that all of the wires are connected to the correct terminals in the plug. Check the fuse resistance with a multimeter

Try plugging another piece of equipment, such as a lamp, into the wall socket. If such does not work, the wall socket is faulty. Use another wall

socket and get an electrician to investigate the fault Try disconnecting extra devices, such as optical drives. If this solves the

problem, the PSU is underpowered and you need to fit one with a higher power rating



5.2.2 Using a multimeter

A multimeter can be used to measure voltage, current and resistance. Voltage readings can be used to determine whether, for example, a power supply is

functioning correctly. Resistance readings can be used to determine whether a fuse or network cable is functioning correctly. Most modern multimeters are

digital and have an LED or LCD readout.

Use a multimeter as follows:

Check the multimeter’s leads before use; do not use leads with damaged or

broken probes or damaged insulation Where possible, connect the multimeter before powering up the circuit and

power down before removing the multimeter Connect the black test lead to the terminal merited COM or REF

Connect the red lead to the terminal corresponding to the measurement to be taken and/or adjust the switch so that it corresponds to the

measurement to be taken. There may be more than one terminal for the red lead; examine the markings around the terminals

Before taking a measurement, check that the leads are connected to the correct terminals and that all meter switches are in the correct position

Turn on the multimeter. Do not adjust switch settings while the multimeter is connected to an energised circuit; this can damage the multimeter

5.2.2.1 Testing fuses

To test a fuse, set the multimeter to measure resistance and touch the probes to each end of the fuse. A good fuse should have virtually zero resistance; a

blown fuse will have virtually infinite resistance.

5.2.2.2 Testing PC power supplies

Power supply problems can be indicated by otherwise inexplicable system lockups or unprompted reboots.



PC Switch Mode power supplies are not user serviceable. Never remove the cover of a Switch Mode power supply. Do not attempt any maintenance beyond

the simple tests described below:

Turn off the PSU at the wall Set the multimeter up as described previously

Insert the black probe into a ground pin Insert the red probe into the pin to be tested

Turn on the PSU, ensuring that you are not touching any part of the PC. Listen for the PSU’s fan spinning up. If the fan does not spin up, the PSU is

either not working or it is not receiving power from the wall outlet Take a reading from the multimeter (Figure 58):

Figure 58 – Testing a Molex connector with a multimeter


Repeat the process for each pin that you wish to test.

5.2.2.3 Testing AC adaptors

You can also use a multimeter to check the output of most types of adapter.

The expected outputs will be shown on the AC adapter label. Do the following:

Set the multimeter up to test for the appropriate voltage range Insert the red probe into the middle of the DC jack

Turn on the multimeter Touch the black probe to the metal part of the outside of the DC jack



5.2.3 Using a power supply tester

A power supply tester is a device designed with the sole purpose of testing PSUs. It is much simpler to use than a multimeter as you do not have to test

each pin in turn.

5.3 Troubleshooting POST Once the CPU has been given the power good signal, the BIOS performs the

POST. The POST is a built-in diagnostic program that checks the hardware to ensure that the components required to boot the PC are present and

functioning correctly.

The POST starts by locating the video card BIOS at the address 0000 in memory. If found, the video card is initialised from its own BIOS; information

about the card manufacturer may also be displayed at this point.

A startup screen is displayed next. More tests on the system, including

counting through system RAM, are performed. If any errors are found, a text error message is displayed. Explanations of such are, usually, found. Once

numeric codes, these messages now tend to be descriptive, such as ‘key stuck’.

You should be able to access CMOS Setup from this point. This allows you to

reconfigure the settings stored in CMOS RAM. The key used to invoke CMOS Setup varies according to the BIOS but it is, usually, <Del>, <Esc>, <F1>,

<F2> or <F10>.

Some PCs indicate that system checks have been successfully completed at this point with a single short beep; the trend for modern computers is to boot

silently.

A search is conducted for further interfaces that may have ROM BIOS chips on

them. This could include SCSI host adapters and network cards. Further information about such may be displayed at this point and their memory

addresses reserved.

The BIOS may display a summary screen about the system configuration. This may scroll by quite quickly; use the <Pause> key if you want to analyse it.

The OS load sequence will now begin.



5.3.1 POST not running

If power is present (for example, if you can hear the fans spinning but the computer does not start or the screen is blank) it is likely that the POST

procedure is not executing. The most likely causes are faulty cabling or a damaged CPU or other motherboard component.

To troubleshoot, try the following tests and solutions:

Ask what has changed: if the BIOS has been flashed and the PC has not booted since, the BIOS update may have failed. Use the reset procedure in

such a case Check cabling and connections, especially if maintenance work has just been

performed on the PC: an incorrectly oriented PATA cable or a badly seated adapter card can stop the POST from running. Correct any errors, reset the

adapter cards and then reboot the PC Check for faulty interfaces and devices: it is possible that a faulty adapter

card or device is halting the POST. Try removing one device at a time to see if this solves the problem or remove all non-essential devices and then add

them back one-by-one Check for logic errors: POST test adapter cards can interpret the debug

codes given by the BIOS. The cards display the codes, thus you can check where the POST has stopped executing

Check for a faulty CPU or BIOS: if possible, replace the CPU and BIOS chips

with known good ones Some motherboards have jumpers to configure modes, such as BIOS

recovery, or CPU settings: if the jumpers are set incorrectly it could cause the computer to not boot. If the computer will not work after being serviced,

check that the jumpers have not been changed

5.3.2 POST errors

If the POST detects a problem, it generates an error message. As the error may prevent the computer from displaying anything on the screen, the error is

often indicated by a series of beeps.



For a beep code, you must decode the pattern of beeps and take the appropriate action (Table 8). Use resources, such as manufacturer websites, to

determine the meaning of beep codes.

Table 8 – POST errors


5.3.3 BIOS time and settings reset

If the CMOS battery is losing power, settings stored in CMOS, such as the date

and time or boot device order, will be lost or corrupted. If the computer is losing the correct time, it can be a sign that the battery is failing. If this

happens, the computer is likely to display the message ‘CMOS Checksum Error’ during the boot process. CMOS errors can also be caused by viruses or a faulty

motherboard or PSU.

Do the following:

Obtain a coin cell battery that is compatible with your motherboard Write down your CMOS settings so that you can restore them later

Unclip the existing battery and take it out. Plug in the new battery and switch the computer back on. Enter CMOS Setup and restore the PC’s

custom settings

Code Meaning

1 short beep Normal POST - system is OK.

2 short beeps POST Error - error code shown on screen.

No beep Power supply or motherboard problem (use a multimeter to check the onboard speaker is functioning).

Continuous beep Power supply, motherboard, or keyboard problem.

Repeating short beeps

Power supply or motherboard problem.

1 long, 1 short beep

Motherboard problem.

1 long, 2 short beeps

Legacy display adapter error (MDA, CGA).

1 long, 3 short beeps

Display adapter error (EGA, VGA).

3 long beeps 3270 keyboard card.



5.3.4 OS searches

Once the POST tests are complete, the BIOS searches the devices as specified in the CMOS boot sequence. If the first drive in the sequence is not found, it

moves on to the next: for example, if drive A contains no disk, the boot sequence goes on to drive C. If no boot devices are found, the system displays

an error message and halts the boot process.

If there is an error at this point, check that the removable drives do not

contain media that are interfering with the boot process and that the boot device order is correctly configured.

The code from the boot sector on a selected device is loaded into memory and

takes over from the BIOS. The boot sector code loads the rest of the OS files into RAM. Error messages received after this can, usually, be attributed to

software or driver, rather than hardware, problems.

5.4 Troubleshooting the motherboard Few problems are actually caused by the motherboard itself. The motherboard

does, however, contain a number of soldered chips and components, which could be damaged by ESD, electricity spikes or overheating. The pins on

integrated connectors can also be damaged by the careless insertion of plugs. These problems are fixable if you are handy with a soldering iron and can

source the replacement parts.

In some cases, errors may be caused by dirt (clean the contacts on the connectors) or chip creep (check that the chips and boards are properly

seated).

5.5 Troubleshooting the CPU CPU failures are rare; most system faults are more likely to be caused by

incorrect configurations, overheating or problems with other failed components. Before assuming that the processor has failed, you should always

rule out other potential problems first.

5.5.1 Unstable operation (system crash or hang) Symptoms, such as system lockup, a blue screen error display or reboot

without warning, are difficult to diagnose with a specific cause, especially if you are not able to witness the events directly. The most likely causes are software

problems, disk problems or malware.

If you can discount these, try to establish whether there is a pattern to the error; if it occurs when the PC has been running for some time, it could

indicate a thermal problem.



Next, check that the power supply is providing good, stable voltage to the system. If you can discount such, you should start to suspect a problem with

memory, the CPU or motherboard.

Inspect the motherboard for any sign of damage. If a component has ‘blown’ it can leave scorch marks. However, you will almost certainly need diagnostic

software to run tests to confirm whether there is a problem. Testing by substituting known good components would be too time consuming and

expensive.

The most likely causes of damage are heat, ESD or a power surge/spike. It is worth investigating any environmental problems or maintenance procedures

that could be the root cause of the error.

5.5.2 Heat Insufficient cooling is the main cause of processor problems. Thermal faults

are, normally, cyclic: a system works for some time, crashes and then works again later because powering down allows the processor to cool. You should

check the following:

Ensure that the CPU fan is working: proper cooling is vital to the lifespan and performance of a processor. If the processor is running too hot it can

decrease performance. A processor that is overheating can cause crashes or

reboot the machine Ensure that the heat sink is property fitted: it should be snug against the

processor. Heat sinks are, usually, ‘stuck’ to the processor using a special heat conductive paste. Some manufacturers, however, use lower quality

paste. In these cases it is possible to clean away the old paste and replace such with better paste, which will help the processor to run at a lower

temperature Always use blanking plates to cover up holes in the back or front of the PC:

holes can disrupt the flow of air and decrease the effectiveness of cooling systems

Speed: is the processor running at the correct speed? Running a processor at a higher clock speed can cause overheating. Double check the voltage and

timing settings in CMOS Setup



5.5.3 CPU not working

If a new processor or an upgrade has just been installed, you should perform the following simple diagnostic attack checks:

Compatibility: check that the processor is supported by the motherboard

Orientation: ensure that the CPU has been inserted correctly into its socket Voltage: check the voltage settings (through CMOS Setup). If the voltage

has been set incorrectly, try to correct such to see if the CPU still works

Configuration: check the CMOS settings and motherboard jumpers to ensure that they are correct

Swap/test by substitution: if the old CPU works, the new one may be faulty

5.5.4 Speed problems

If a system is slow or reports the wrong CPU speed at boot time, you should perform the following diagnostic checks:

Setup: verify the CMOS configuration (on a very old PC) or motherboard

jumper settings

Throttling: most CPU models will have protection circuitry to slow down when they get too hot. You should investigate why the CPU is overheating

(for example, has the fan stopped working or is the heat sink clogged with dust)

If a user complains that a system is slow, try to verify that it is not a software

or network problem. You can use Task Manager to display the CPU and network utilisation: if the CPU utilisation consistently runs at 90% to 100%, it

is likely that a faulty application process is to blame.

5.6 Troubleshooting memory If you suspect that memory is faulty, first check that such is seated properly in

the connector and that the modules are compatible with the motherboard and slots in which they are installed. Next, use a diagnostic utility to verify the

chips.

5.6.1 Lockups Faulty memory chips can cause lockups and blue screens. There are various

troubleshooting utilities designed to test memory chips. Windows Vista and Windows 7 ship with a memory tester; it is available through booting from the

product disc and selecting the repair option. Testing can take a long time to complete as it should, normally, run several times to fully rule out a hardware

failure.



5.6.2 Windows Memory Diagnostics tool

Windows Vista and Windows 7 include the Windows Memory Diagnostics tool to test memory chips for errors (Figure 59). You can either run such from

administrative tools or boot to Windows pre-installation environment (PE) and select Windows Memory Diagnostics. Select Restart and check for

problems; the computer will restart and run the test.

Figure 59 – Windows Memory Diagnostics tool


If errors are found, first check that all the memory modules are correctly

seated. Remove all memory modules but one and retest. You should be able to identify the faulty board via a process of elimination. If a known good board is

reported faulty, the problem is likely to be in the motherboard.



5.6.3 New memory not recognised

After performing a memory upgrade, rebooting and then checking the memory count, the memory may not be recognised. You should first check that the

modules have been installed correctly into their sockets. If this does not solve the problem, check the following:

Memory type:

o Does the motherboard support the memory card capacity that you have

installed (for example, a board may be restricted to 1 GB in total or may not support individual modules larger than 512 MB)?

o Does the motherboard chipset support the memory technology that you have installed (for example, registered or ECC)?

Configuration: o Are the memory banks complete?

o Have the memory banks been filled in the correct sequence? o Is the motherboard operating in dual channel mode?

In all cases, refer to the motherboard documentation for guidance.

5.7 Troubleshooting adapter cards and I/O ports

If an adapter card is not recognised after installation, the first thing to check is that it is compatible, the next that it is inserted correctly and then that there is

no dirt affecting the connection between the contacts on the card edge and slot. If an adapter card stops working, try reinstalling the driver and then

check for seating or dirt issues.

It is possible to perform ‘loopback’ tests on all types of I/O and communication ports. Loopback tests are performed by using a special device, in the form of a

connector plug, that routes a port’s output lines directly back to its input lines.

These are used in conjunction with third-party diagnostic programs (for example, PassMark, PC-check and MicroScope) that send test data to the port;

the diagnostic software then checks that the data is sent back correctly by the loopback plug.

USB ports are designed to be very simple. If a device requires driver software,

you should install such first (before connecting the device). You then simply attach the device and it should be detected and installed. If a device is not

recognised, it will appear as an unknown device in Device Manager. In such a case, try installing a new driver, using a different port, or replace the cable.

Many devices are USB 2 instead of the original USB standard. If you plug a high speed device into a low speed device/port, a warning message is

displayed and the device will operate at a low speed.



Concluding remarks

In this unit, we introduced the basic computer problems that might be experienced as well as how to troubleshoot components. Some problems that

we recognised were experienced after performing an upgrade or reboot.

In the next unit, we will investigate computer system maintenance and

upgrade.

Self-assessment

Test your knowledge

1. Explain the Windows Memory Diagnostics tool.

2. Briefly discuss what could decrease the performance of a computer system.

Unit 6 – System Maintenance and Upgrade Page 123


Unit 6: System Maintenance and Upgrade


Learning outcome

LO4 Be able to undertake routine maintenance on

computer systems

Assessment criteria AC4.1 Perform routine maintenance tasks on a computer

system AC4.2 Upgrade the hardware and software on a computer

system

Learning objectives


Use utilities to optimise performance Identify OS, driver and firmware updates

Use procedures and tools to back up and migrate user data Describe the different malware threats

Identify the symptoms of different types of malware infection

Use secure computer practices to reduce the risk of malware Operate antivirus software to protect computers against infection

Introduction In the previous unit, you learnt how to troubleshoot problems associated with

computer systems.

In this unit, we will identify and discuss the functions of utility software. We

will also focus on the different methods of performing backups and restoring data. We conclude by discussing the types of malware that are harmful to

computer systems. You will learn how to identify malware using their common symptoms, how to remove such and how to prevent such in computer

systems.



6.1 Maintaining and optimising disk drives

Of all computer sub-systems, hard drives and file systems probably require the most attention to keep in optimum working condition. They are, generally,

subject to three main problems:

1. Fragmentation: ideally, each file would be saved in contiguous clusters on a

disk. In practice, over time, as files grow, they become fragmented (written to non-contiguous clusters), reducing read performance

2. Capacity: typically, much more file creation occurs on a computer than file deletion. This means that capacity can reduce over time, often quite

quickly. If a system’s disk has less than 20% free space, performance can become impaired. When free space drops to below 200 MB, a low disk

space warning is generated 3. Damage: hard disk operations are physically intensive and the platters of

such are easy to damage, especially in the case of a power cut. If a disk does not recognise that a sector is damaged, files can become corrupt

The above can be addressed by the systematic use of disk performance tools.

These tools should be run regularly (at least every month) and before installing

software applications.

6.2 Utility software

6.2.1 Check Disk The Check Disk (chkdsk) utility checks the integrity of disks and can repair

detected problems (Figure 60):

Figure 60 – Check Disk utility




There are three ways to run Check Disk, namely:

1. No option selected: this runs in Read-only Mode 2. Automatically fix file system errors: file system errors are caused by

crashes, power loss and the like. At a command line, use chkdsk volume:

/f, where volume refers to the drive letter

3. Scan for and attempt to recover bad sectors: bad sectors are damaged in the actual drive. If a drive has many bad sectors, it is probably nearing the

end of its useful life. You will be prompted to save any recoverable data, which is copied to the root directory as filennnn.chk files. At a command

line, use chkdsk volume: /r, where volume refers to the drive letter

Check Disk cannot fix open files, so you may be prompted to schedule the scan

for the next system restart. A version of Check Disk (autochk) will also run automatically if the system detects file system errors.

Other main parameters and switches for the command line version are

summarised in Table 9:

Table 9 – Check Disk command line switches

Switch Use

path Specifies a path (and, optionally, a file name) to check

/x Forces the volume to dismount; this will cause file errors for users with

open files on the volume

/I /c On NTFS volumes only; it skips parts of the checking process


Check Disk can take a long time to scan and fix errors on a large disk. You

cannot cancel this utility once started, so it may be wise to run a read-only

scan first.



6.2.2 Disk Defragmenter

Disk Defragmenter (‘defrag’) reorganises a drive to store information relating to each file in contiguous sectors of the disk. This improves performance by

reducing the time required to load a file. Disk Defragmenter can also move data to the start of a disk, leaving a single free area for use by new files

(Figure 61):

Figure 61 – Disk Defragmenter in Windows XP


You can defragment local and external hard disks and flash drives but you cannot defragment optical discs or network drives.

Although it is possible to run this utility in the background while you work, it

will slow down your machine and prevent defragmentation of open files. It is better to run Disk Defragmenter when your computer is not being used. It may

also be necessary to disable applications that run in the background, such as antivirus software, Task Scheduler or a screen saver.

The defragmenter requires above 15% of free disk space to work effectively. If insufficient free disk space is available, some files may not be defragmented.

To make the defragmenter run more efficiently, restart the computer before running such to clear out the page file.



Windows Vista and Windows 7 automatically schedule the defragmenter to run using Task Scheduler (Figure 62):

Figure 62 – Disk Defragmenter in Windows 7


In Windows Vista you need to install SP1 before you can select which drive to defragment via the GUI. Also, the GUI tool does not display progress.

At a command line, the basic syntax is defrag volume, where volume refers to

the drive letter or volume name. The main switches for Windows Vista and

Windows 7 are as follows (Table 10):

Table 10 – Disk Defragmenter command line switches

Switch Use

/a Analyses the volume and displays a report

/f Forces a volume to be defragmented

/v Displays a complete analysis and defragmentation reports

/c Defragments all volumes

/e Defragments all volumes except those specified

/h Runs the tool at normal (rather than at low) priority

/m Performs defragmentation of multiple volumes in parallel

/x Consolidates free space (tries to make all empty sectors contiguous); this

option is useful if you wish to shrink a volume




6.2.3 Disk Cleanup

Applications and installation programs create temporary and cached files as part of their normal operations; these files consume disk space. The Disk

Cleanup utility (cleanmgr) (accessed via the System Tools folder in the Accessories group on the Programs menu) provides a means of deleting

unwanted temporary files created by installation programs, applications and cached Internet files (Figure 63). There is also an option to compress unused

files but not in Windows Vista or Windows 7.

Figure 63 – Disk Cleanup in Windows 7


6.2.4 Task Scheduler

Task Scheduler, as its name suggests, set tasks to run at a particular time. Tasks can be run once at a future date/time or according to a recurring

schedule. A task can be a simple application process or, more commonly, a batch file or script.



Task Scheduler is accessed via Control Panel in Windows XP (Figure 64) and via Administrative Tools in Windows Vista and Windows 7. Apart from defining

the path to a file or script that you want to execute and setting the schedule, you should enter the credentials that the task will run under (if the selected

user account does not have permission, the task will not run).

Figure 64 – Scheduled task properties in Windows XP


Windows Vista and Windows 7 Task Scheduler (Figure 65) come with numerous enhancements. Many of the processes come with predefined task

schedules (Disk Defragmenter, for instance, is now configured to run

automatically by default). Other enhancements include:

You can define triggers other than simple schedules (for example, running a task when the machine wakes from sleep or hibernation)

You can add multiple actions under a single task You can view a log of events connected to a task

You can organise tasks in folders and there are tools for managing such



Figure 65 – Task Scheduler in Windows 7


6.2.5 Patch management Patch management is a key PC maintenance task that ensures that PCs

operate reliably and securely. A patch or update is a file containing replacement system or application files. The replacement files fix some sort of

coding problem in the original file. The fix could be made to improve reliability, security or performance.

A SP is a collection of previous updates but may also contain new features and

functionality. While SPs are not paid for, they do require you to follow the upgrade process to ensure that software and, to a lesser extent, hardware will

be compatible. You should always make a backup before applying SPs. SPs can be downloaded from Microsoft’s website or shipped on disc. The later

manufacturing releases of setup media tend to include the latest SP.

Microsoft products are subject to their Support Life Cycle Policy. Windows

versions are given five years of mainstream support and five years of extended support (during which only security updates are shipped). Support is

contingent on the latest SP being applied (non-updated versions of Windows are supported for 24 months following the release of a SP).



6.2.6 Update policy

Later copies of setup media have built-in SPs but you should always try to keep Windows up to date. Failing to do so can cause anything from corrupt

onscreen graphics, when using new video drivers, to complete system crashes and vulnerability to malware.

There are two approaches to applying updates, namely:

1. Apply all the latest patches to ensure that the system is as secure as possible against attacks and software flaws

2. Only apply a patch if it solves a particular problem being experienced

You also need to keep up to date with security bulletins. Updates (particularly SPs) can cause problems, especially software application compatibility. Best

practice is to test updates on a non-production system before rolling such out.

Some applications may require the OS to be patched to a certain level. To check the current build of Windows, run winver.

6.2.6.1 Windows and automatic updates

In Windows XP, Windows Update is a website (update.microsoft.com) that

hosts maintenance updates for different versions of Windows and Internet

Explorer (Figure 66). An active control installed on a computer enables such to browse the site and select updates for download and installation, using the

Background Intelligent Transfer Services (BITS) Protocol.

Figure 66 – Selecting updates for Windows XP via Windows Update


http://www.update.microsoft.com/



Windows Update, further, hosts critical updates and security patches (code to fix security vulnerabilities in Windows and its associated software) as well as

optional software and hardware updates to add or change features or drivers.

The WindowsUpdate.txt log (stored in the System Root folder) records update activity. If an update fails to install, you should check the log to find the cause;

the update will fail with an error code that you can look up on the Microsoft Knowledge Base. If an update causes problems, you can use the Add or

Remove Programs applet to uninstall such.

During setup, Windows can be configured to check for system updates (via the Internet) and download such as needed. In Windows XP, the Automatic

Updates applet (opened from Control Panel or on a tab in the System

Properties dialog box) allows you to configure when updates are scheduled and what level of user interaction is required (Figure 67):

Figure 67 – Automatic Updates in Windows XP


In Windows Vista and Windows 7, update settings are configured via the Windows Update applet in Control Panel.

6.2.6.2 Application updates

Software applications, especially those with browser plug-ins, may also need updating with the latest patches. Applications can contain security

vulnerabilities in the same way as an OS; in fact, applications are targeted more aggressively than Windows itself as attackers recognise that they are

less likely to be patched than the OS.



6.2.6.3 Antivirus software updates

It is particularly important that antivirus software, or any other type of malware-blocking software, be updated regularly. Two types of update are

generally necessary:

1. Virus definitions/patterns: this is information about new viruses; these may be available daily or even hourly

2. Scan engine/components: this fixes problems or makes improvements to the scan software itself

There is, usually, an option within the software program to download and

install updates automatically. Updates are also scheduled to take place daily by

default; this can be configured via the Client Management settings. Note the option to retry and randomise the start time: this helps to ensure that an

update will take place (Figure 68):

Figure 68 – Scheduling regular updates


6.2.6.4 Driver updates

Windows ships with a number of core and third-party hardware drivers.

Updates for these devices can be obtained via Windows Update, however, they will be listed as optional updates and might thus not install automatically.

Most of the time, third-party drivers should be obtained from the vendor’s

website. To update, you download the driver files and install them using the

supplied setup program (or extract them manually and save such to the hard disk). You can then use the device’s property dialog in Device Manager to

update the driver. You can either scan for the update automatically or point the tool to the updated version that you saved to disk.



6.2.6.5 Firmware updates

Motherboard manufactures may regularly update their BIOS to fix bugs, solve OS incompatibilities or add new features. You should visit your motherboard

manufacturer’s website regularly to check if and when upgrades are available.

In addition to the PC BIOS, you may need to update the firmware on other devices, such as drive units, printers and networking equipment. Devices

directly attached to a PC (via USB or Firewire) can, normally, be updated from Windows using a setup utility provided by the vendor. A network device would,

typically, be updated using its management software or web configuration interface (Figure 69):

Figure 69 – Updating the firmware on a SOHO DSL router using its web interface




6.3 Data backup

One of the most important operations in computing is the creation of secure backups of data files. Typically, network backups take place using a tape

system, which has the advantages of high capacity, relatively low cost and

portability. For this type of backup, advanced backup software, capable of backing up online databases and remote systems, is required.

When a computer is connected to a network, it is bad practice for a user to

store data locally (on the client PC’s hard drive). Network home folders and the use of scripts to copy data can help users to transfer such to a file server,

where it can be backed up safely.

Personal backups are necessary for home users or workgroups, where no central file server is available. In such a scenario, the backup software supplied

with Windows XP (ntbackup) is serviceable (Figure 70):

Figure 70 – Performing a backup in Windows XP




Windows Vista (Figure 71) supplies a simplified wizard-driven tool with options to back up the whole system (an image) or just user data to an appropriate

device (hard disk or recordable DVD).

Figure 71 – Windows Vista Backup and Restore Centre


The backup tool included with Windows 7 (Figure 72) has the ability to back up selected locations as well as the option to make system images in all versions.

Windows Home editions are restricted to backing up to local drives or removable media while Business/Ultimate editions can back up to a network

share (in Vista, network locations can be selected in all editions except Home Basic).

Figure 72 – Windows 7 Backup and Restore Centre




A network backup requires high capacity media with multiple GBs. This requires the use of tape-based systems, such as linear tape open (LTO). For a

workgroup or workstation, tape-based media might be too expensive. Alternatives include removable hard disks or even flash memory/USB drives.

6.3.1 Backup types A backup is, usually, performed using one of three main types, namely:

1. Full 2. Incremental

3. Differential

A full backup includes all selected files and directories while incremental and differential backups check the status of the archive attribute before including a

file. The archive attribute is set whenever a file is modified. This allows for backup software to determine which files have been changed and, therefore,

need to be copied.

Table 11 summarises the backup types:

Table 11 – Choosing a backup type


The criteria for determining which method to use is based on the time it takes to restore vs the time it takes to back up. Assuming a backup is performed

every working day, an incremental backup only includes files changed during that day, while a differential backup includes all files changed since the last full

backup.

Type Data Selection Backup /

Restore Time Archive Attribute

Full All selected data regardless of when it has previously been backed up

High / low (one tape set)

Cleared

Incremental New files and files modified since the last backup

Low / high (multiple tape sets)

Cleared

Differential All data modified since the last full backup

Moderate / moderate (no more than 2 sets)

Not Cleared



Incremental backups save on backup time but can be more time consuming when the system must be restored. The system must be restored from the last

full backup set and then from each incremental backup that has subsequently occurred. A differential backup system, in turn, only involves two tape sets

when a restore is required.

Do not combine differential and incremental backups. Use full backups interspersed with differential backups or full backups interspersed with

incremental backups.

Most software also has the capacity to do copy backups. These are made outside of the tape rotation system (ad hoc) and do not affect the archive

attribute.

6.3.2 Restoring data and verifying backups It is critical to test that backup operations function properly. The following

represents some of the main backup security issues:

Compatibility: a tape backup is useless without a drive capable of reading the media. Most drives can read tape formats from the previous generation

or more. If a Legacy drive fails and there is no replacement available, there is a very real risk to the security of an organisation’s data

Error detection: problems with the tape or configuration can cause backup

jobs to fail. Depending on the error, the whole job could be cancelled or some data may not get backed up. Backup software, usually, have the

facility to verify a backup (this makes the backup operation take longer) and report errors to the log

Configuration: when setting up a new job (and periodically thereafter), it is wise to check the media catalogue to ensure that all expected data has been

backed up Test restore: another option is to test that a restore operation can be

performed successfully. This is important when using new backup software; to test old tapes, to check a new job and to perform random spot checks.

When you do a test restore, you redirect data to a different folder to avoid overwriting live data (Figure 73)



Figure 73 – Redirecting file output for a restore operation


6.3.3 Shadow copies

A shadow copy or volume snapshot service (VSS) underpins the backup and system restore functionality in Windows Vista and Windows 7. The VSS creates

snapshots of each volume; this allows the backup program to access ‘open’ files and to preserve multiple system restore points.

Shadow copies also enable the previous versions feature. If you open a file or

folder’s property dialog, you can use the Previous Versions tab to locate older copies of a file or folder. These can be restored – either by copying the version

to a new file (select Open or Copy) or by overwriting the current file (select Restore) (Figure 74):



Figure 74 – Folder properties in the Previous Versions tab


Previous file or folder versions are made available for either system restore

points or backup copies.

6.3.4 Restoring user profiles A backup is, usually, made with the purpose of being able to restore files and

settings to the same version of Windows. Data file backups can also be used to restore data to a new computer and there are circumstances when you would

want to restore data and settings (a whole user profile) from a computer running an older version of Windows to one running a newer version. Microsoft

has released several tools fit for these purposes.

6.3.4.1 User State Migration tool

If performing a clean installation or providing a user with a new computer

rather than performing an upgrade, you may want to retain user settings from the old PC. These may include desktop and browser configurations, application

settings and data files. The User State Migration tool will assist in this process as part of a large scale deployment. The files for the User State Migration tool

are found in the Windows Automated Install Kit (AIK), available from Microsoft’s website.



The User State Migration tool consists of two tools, namely:

1. ScanState: this is used on the old PC to copy files and settings to a migration store. The tool is used in conjunction with extensible markup

language (XML) configuration files that specify what to back up 2. LoadState: this is used on the new PC to restore files and settings, again

using XML configuration files

6.3.4.2 File and Settings Transfer Wizard

This program provides a friendly interface to the User State Migration tool, designed for home users. Again, it is useful if you are planning to perform a

clean installation or for users that have bought a new computer and want to

transfer settings from an old computer.

To perform such a transfer, you will need to do the following:

Put the Windows setup disc in the old computer or installation and choose Perform Additional Tasks > Transfer Files and Settings

Select Old computer and click Next Choose a location in which to store the data or transfer such to the new

computer. Click Next Choose what you want to transfer and click Next. Acknowledge any

warnings and click Next again (Figure 75):

Figure 75 – File and Settings Transfer Wizard


Upgrade the target workstation and use the wizard on that computer to complete the process



6.3.4.3 Windows Easy Transfer tool

In Windows Vista and Windows 7, the Windows Easy Transfer tool replaces the File and Settings Transfer Wizard. It, essentially, has the same functionality

except that it does not support versions of Windows older than Windows XP (the Vista version can collect data files only from Windows 2000). The

Windows Easy Transfer tool cannot be used to transfer from a 64-bit version of Windows to a 32-bit version, though it can transfer from a 32-bit source to a

64-bit destination. The tool also does not transfer applications.

To perform a transfer, you will need to do the following:

To transfer files, first run the Windows Easy Transfer tool to create a client

version of the software for your old PC (if the old PC is Windows Vista and you are moving files to Windows 7, create a client version in Windows 7 and

install such on the Windows Vista PC, rather than running an older client version on the old PC)

Install and run the Windows Easy Transfer tool on the old PC and choose a storage location as well as what you want to transfer (Figure 76):

Figure 76 – Running the Windows Easy Transfer tool to collect data from an old PC




Run the Windows Easy Transfer tool on the new PC and select the transfer file that you made. You can customise what gets restored or use Advanced

Options to map an account from the old PC to a differently named account on the new PC (Figure 77). This is also necessary if you want to transfer

data from a domain account to a non-domain account

Figure 77 – Mapping user accounts in the Windows Easy Transfer tool


6.4 Computer malware

6.4.1 Malware types

Malware is a term to describe malicious software threats and social engineering tools designed to vandalise or compromise computer systems.

6.4.1.1 Computer viruses and worms

Computer viruses are programs designed to replicate and spread among computer systems. They produce a wide variety of PC symptoms and, in

extreme cases, can cause permanent damage or loss of files.



There are several different types of virus and they are, generally, classified in terms of the different ways in which they can affect a computer. Examples

include:

Boot sector viruses: these attack the boot sector information, the partition table and sometimes the file system

Program viruses: these are sequences of code that insert themselves into another executable program. When an application is executed, the virus

code becomes active Macro-viruses: these viruses affect Microsoft Office documents by using the

programming code that underpins macro-functionality maliciously Worms: these are memory resident viruses that replicate over network

resources

Viruses are classified as software that attempts to self-replicate to other files,

disks, computers or networks. However, a virus’s payload can be programmed to perform many different actions, especially in the case of program and

macro-viruses. A virus’s payload may be programmed to display silly messages, corrupt or delete documents, damage system files or install

spyware.

Most viruses must be activated by the user, thus they need some means to trick the user into opening an infected file. E-mail attachment viruses (usually

program or macro-viruses in an attached file) often use the infected host’s electronic address book to spoof the sender’s address when replicating.

Example Jim’s computer is infected with a virus and has Alan’s

e-mail address in his address book. When Sue gets an infected e-mail, apparently sent by Alan, it is the virus on

Jim’s computer that has sent the message.

Viruses can also use application exploits to replicate without user intervention.

This is why it is imperative to apply security patches to OS and application software, especially web browser and e-mail software, promptly.

6.4.1.2 Trojans

Other types of malware are not classified as viruses as they do not necessarily

try to make copies of themselves. They can, however, be just as much of a security threat as viruses. A Trojan is a program that pretends to be something

else (named after the Trojan horse in Greek history). For example, an amusing background may also install a key logger or rootkit.



6.4.1.3 Spyware and adware

Spyware and adware are classes of program that monitor computer and Internet activity; it then sends this information to someone else. If a user is

not informed, it is spyware; if a user accepts the use of their data, it is adware.

Aggressive spyware programs, known as ‘key loggers’, actively attempt to steal confidential information, for example, capturing credit card numbers by

recording key strokes entered into a web form.

6.4.1.4 Rootkits

A rootkit is a set of tools designed to gain control of a computer without

revealing its presence. The general functions of a rootkit are:

Replacing key system files and utilities to prevent detection and the eradication of the rootkit itself. The most sophisticated rootkits can install

and run with system or kernel level privileges Providing a backdoor channel for the rootkit handler to reconfigure a PC,

steal information or install additional spyware or other malware remotely

Rootkits are often used to compromise a number of computers (botnets) with the purpose of performing wide-scale denial of service (DoS) attacks against

Internet hosts. Rootkits are also used by attackers to conceal their actions (attacks or spam appear to come from the corrupt computer system). Rootkits

may also be deployed as part of digital rights management and copy protection mechanisms. Sony infamously released a music player for its extended copy

protection CDs that also installed a rootkit.

6.4.1.5 Phishing

Phishing is a technique that tricks a user into revealing confidential information

by requesting such in an official-looking e-mail (perhaps pretending to come from a bank or genuine service provider). The e-mail will contain a link to a

counterfeit site or to a valid site that is vulnerable to a cross-site scripting attack. The user is prompted to input confidential data, such as an online bank

account number and password, which are then stolen by the attacker.

6.4.1.6 Spam

Spam is unsolicited e-mail messages, the content of which is, usually, pornography, miracle cures for various personal conditions or bogus stock

market tips. Spam is also used to launch phishing attacks and spread worms

and viruses.



Spam needs to be filtered before it reaches a user’s inbox. Most e-mail applications now ship with junk mail filters or you can install a filter from the

organisation’s mail gateway.

The main problem with spam filters is that they can block genuine messages too, leading to missed communication.

6.4.2 Malware symptoms

6.4.2.1 General symptoms

The following are examples of symptoms that may indicate a virus infection:

A computer fails to boot or experiences lockups The file system or individual files are corrupt or deleted

Date stamps and file sizes of infected files change Permission attributes of files change, resulting in access denied errors

New executable files (exe and dll) appear in system folders. They may have file names that are very close to valid programs (for example, notpad.exe)

Strange messages or graphics appear onscreen Security applications (antivirus, firewall, Windows Update) stop working

Applications for Windows tools (for example, Notepad) stop working Performance at startup or in general is very slow

Network performance is slow or Internet connections are disrupted

Any sort of activity or configuration change that was not initiated by the user is

a good reason to suspect malware.

6.4.2.2 Spyware, adware and web browser symptoms

Malware often targets web browsers. Remember that malware is not always destructive. Malware, such as adware and spyware, is designed with

commercial or criminal intent, rather than to vandalise a computer system.

Common symptoms of infection by spyware or adware are:

Pop-ups or additional toolbars The home page or search provider changes suddenly

Searches returning results are different to other computers

Slow performance and excessive crashing (faults) Viruses and Trojans may spawn pop-ups without the user opening the

browser



Another major symptom is redirection: this is where the user tries to open one page but gets sent to another; often this may imitate the target page. In

adware this is just a blunt means of driving traffic through a site, but spyware may exploit such to capture authentication details.

6.4.2.3 Trojan, rootkit and botnet symptoms

Malware that tries to compromise a PC will try to create a communication

channel with its ‘master’. If the firewall is still working, you may see unfamiliar processes or ports trying to connect to the Internet.

Remember that the most powerful malware can disguise its presence.

Example

The Netstat utility shows open ports on a PC. A rootkit may replace Netstat with a modified version that does not show

the ports in use by the rootkit.

6.4.3 Virus alert hoaxes Hoax virus alerts are quite common. They are often sent as mass e-mails as a

prank. Some hoax virus alerts describe a number of steps that you “must take” to remove the virus, however, following these steps may cause damage to

your computer.

If you have an antivirus, the vendor may provide a virus alert service. You should use the antivirus to remove a virus from an infected file.

Rogue antiviruses are particularly popular to disguise Trojans. In the early versions a website would display a pop-up disguised as a normal Windows

dialog with a fake security alert, warning the user that viruses have been detected. As browser and security software have moved to block such, cold

calling vulnerable users claiming to represent Microsoft Support has become popular.



6.4.4 Preventing malware infection

There are numerous sources of malware infection. The primary sources are:

Visiting ‘unsavoury’ websites with an unpatched browser, low security settings and no antivirus software

Opening links in unsolicited e-mails Infection from another compromised machine on the same network

Executing a file of unknown provenance: e-mail attachments are still the

most popular medium but others include file sharing sites, websites in general, attachments sent via chat/instant messaging, AutoRun USB sticks

and CDs

A number of steps can be taken to reduce the risk and impact of software infection. These include:

Perform regular backups that allow for data to be recovered in the case of

loss owing to a virus infection Apply OS and application security patches

Do not allow users to install their own software programs. If necessary, measures, such as removing or disabling removable drives, can be

employed. Windows-based systems allow the administrator to determine who can run new programs, install new software or download files from the

web

Install and use an antivirus package. The virus package must be kept up to date with updated signatures and definitions; viruses are continually being

developed thus the latest signatures offer the most protection Select antivirus software that scans automatically (on access)

Configure filtering on the messaging server as this will prevent most of the unsolicited messages (spam) arriving at the server from getting to the user’s

mailbox Do not log on with administrator privileges except where necessary. Limit

administrative privileges to a few select accounts. Keep passwords for these accounts secure

Educate users about not running attachments and supplement this with procedures that will prevent files, such as executables and Microsoft Office

macros, from being allowed to run. This could be accomplished, for instance, by only allowing digitally signed code to be executed

Audit system events, such as logons, and review logs for unusual activity

Establish a procedure for recovery following virus infection to minimise the spread and effects of such



Routine procedures, such as applying critical and security patches to the OS and applications as well as updating virus definitions and malware threats in

antivirus software, should be automated, where possible, or performed according to a strict schedule.

An organisation needs to develop and enforce effective policies, backed up by

disciplinary procedures to supplement training and education programmes.

6.4.4.1 Antivirus software

Antivirus software uses a database of known virus patterns (definitions) as well as heuristics malware identification techniques to try to identify infected files

and prevent viruses from spreading. ‘Heuristics’ mean that the software uses

knowledge of the sort of things that viruses do to try to spot (and block) virus-like behaviour.

Antivirus software scans files and blocks access if it detects anything

suspicious. The user can then decide either to try to disinfect the file, quarantine such (block further access) or delete such.

The antivirus scanner also runs at boot time to prevent boot sector viruses

from infecting the computer. Most types of software can also scan system memory (to detect worms), e-mail attachments, removable drives and network

drives.

The latest antivirus software, usually, includes anti-Trojan software as well as spam, adware and spyware blockers.

Antivirus software tends to come as either personal security suites, designed to protect a single host, or network security suites, designed to be centrally

managed from a server console. Most antivirus software is designed for Windows PCs and networks, as these are the systems targeted by most virus

writers; however, software is also available for Linux and Apple Mac OSs.

Some of the major vendors are Symantec (including the Norton brand), McAfee, Trend Micro, Kaspersky, ESET (NOD32) and BitDefender.

Many antivirus vendors offer applications that are specifically designed for the

protection of organisations connected to the Internet. For example, Symantec Endpoint Protection (Figure 78) can be configured to download virus definitions

and product updates to clients automatically, scan Microsoft Exchange and Lotus Notes messaging systems, and protect against Trojans and spyware.



Figure 78 – Symantec Endpoint Protection


The following steps use Symantec Endpoint Protection as an example of

scanning for viruses.

Scanning for viruses

Open the antivirus application and select the Scan for Threats option

Check the drives and/or folders that you want to scan You can choose between an active scan of commonly targeted folders and

file types, a full scan or custom scan (Figure 79):

Figure 79 – Symantec Endpoint Protection scanning




On access scanning

Almost all security software is now configured to scan on access. This reduces performance somewhat but is essential to maintaining effective protection

against malware.

When configuring antivirus software, it is vital to configure proper exceptions (Figure 80). Real-time scanning of some system files and folders (most notably

those used by Windows Update) can cause serious performance problems.

Figure 80 – Configuring on access scans


Scheduled scanning

All security software supports scheduled scanning. This can, however, seriously affect performance so it is best to run such when a computer is otherwise

unused. Symantec Endpoint Protection performs an active scan at startup but the user can define any type of scan to run to a schedule of their own

choosing.



Quarantining and remediating infected systems

Malware, such as worms, propagate over networks. This means that one of the first actions should be to disconnect the network link. If a file is infected with a

virus, you can use antivirus software to try to remove the infection (cleaning), quarantine the file (the antivirus software blocks any attempt to open such) or

erase the file. You can configure the action that the software should attempt when it discovers malware as part of a scan (Figure 81):

Figure 81 – Configuring scan remediation options in Symantec Endpoint Protection


If you cannot clean a file and have a backup copy, use such to restore the file. Check the files that you restore to ensure that your backups are not also

infected.

The only other alternative is to remove the virus manually or to reformat the

machine, reinstall software and restore data files from a (clean) backup.

For assistance, check the website and support services for your antivirus software. In some cases, you may have to follow a further procedure to

remove the virus or Trojan, such as booting into Safe Mode or Recovery Console.

Antivirus software will not necessarily be able to recover data from infected

files. Also, if a virus does disrupt the computer system, you might not be able to run antivirus software anyway and would have to perform a complete

system restore.

Removing backdoor applications

Antivirus software may have routines for removing Trojans and rootkits but the

most secure way is to quarantine the computer by removing it from the network. You could use Safe Mode or secure boot tools, such as booting to the

PE from the Windows setup disc, to try to remove the malware.



If the malware cannot be removed, repartition and reformat the drives, then reinstall the OS, applications and data from a backup (provided that you have

a backup that was made before the installation of the backdoor).

It is also important to configure a firewall on the network to block outgoing communication. This makes it more difficult for the backdoor application to

send data back to the attacker.

Most antivirus software now combines the functionality of basic malware detection with the capabilities of previously standalone programs, such as

personal firewalls, adware or spyware detection and intrusion detection (Figure 82):

Figure 82 – Monitoring services and intrusion attempts in Symantec Endpoint

Protection


6.4.4.2 Windows security tools

As Internet threats have become more prevalent, security features have

become a core part of Windows.



Security Centre

The Security Centre Control Panel applet was introduced in Windows XP SP2 (Figure 83) to provide a central location for monitoring the status of security

features (Windows Update, Firewall and Antivirus). Windows also displays alerts in the notification area if security features are missing or disabled.

Figure 83 – Security Centre in Windows XP


In Windows 7, the applet is called ‘Action Centre’.

Windows Defender

Windows Vista and Windows 7 ship with the antispyware program Windows Defender. This provides protection against programs that might try to modify

the web browser or startup programs, display excessive pop-ups or try to track web activity. Note, however, that this is not an antivirus or anti-Trojan tool.



If you have antivirus software, you may want to disable Windows Defender as the two may conflict. Do the following:

Open Windows Defender from the Control Panel and select the Tools option

Click Options, then scroll to the bottom of the dialog and uncheck Use Windows Defender (under Administration Options) (Figure 84):

Figure 84 – Windows Defender


Concluding remarks In this unit, we introduced third-party utilities that can be used to support the

OS to perform system maintenance. We also discussed the various Windows

file management and backup procedures. The unit concluded by exploring the most common types of malware that can cause harm to computer systems as

well as the various methods to mitigate such.

Self-assessment

Test your knowledge

1. Define utility software, scheduled maintenance tasks, patches and updates.

2. Briefly discuss the types of malware that can affect a computer and how to protect against such.

Glossary Page 156


Glossary BIOS Basic input-output system

CMOS Complementary metal-oxide semiconductor

CPU Central processing unit

DNS Domain name system

ECC Error checking and correction

ESD Electrostatic discharge

FAT File allocation table

FTP File Transfer Protocol

GUI Graphics user interface

HBA Host bus adapter

HDD Hard disk drive

HTTP Hypertext Transfer Protocol

IDE Integrated drive electronics

I/O Input/output

NAS Network attached storage

NTFS New technology file system

OS Operating system

PATA Parallel advanced technology attachment

POST Power-on self-test

PSU Power supply unit

RAID Redundant array of independent disks

RAM Random access memory

ROM Read-only memory

SATA Serial advanced technology attachment

SCSI Small computer system interface

SP Service pack

USB Universal serial bus

Bibliography Page 157


Bibliography Elango, S.; Jothi, A.; Malaiarasu, P.; Ramachandran, V. & Rhymend-Uthariaraj,

V. 2005. Computer science: volume 1: concepts. [Online] Available at: http://www.textbooksonline.tn.nic.in/books/11/std11-compsci-em-1.pdf

[Accessed: 08 October 2014].

Doctor, Q.; Dulaney, E.A. & Skandier, T. 2012. CompTIA A+ complete study guide. 2nd edition. Indianapolis: Wiley.

GTS Learning. 2013. CompTIA A+ certification: 801 support skills: study

notes. [Online] Available at: https://s3.amazonaws.com/gtslearning-

samples/comptia-aplus-220-801-courseware-sample.pdf [Accessed: 08 October 2014].

http://www.textbooksonline.tn.nic.in/books/11/std11-compsci-em-1.pdf

https://s3.amazonaws.com/gtslearning-samples/comptia-aplus-220-801-courseware-sample.pdf

https://s3.amazonaws.com/gtslearning-samples/comptia-aplus-220-801-courseware-sample.pdf


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Bedfordview Campus

9 Concorde Road East, Bedfordview P.O. Box 1389, Bedfordview, 2008 Tel: +27 (0)10 595 2999, Fax: +27 (0)86 686 4950 Email: [email protected]

Bloemfontein Campus

Tourist Centre, 60 Park Avenue, Willows, Bloemfontein P.O. Box 1015, Bloemfontein, 9300 Tel: +27 (0)51 430 2701, Fax: +27 (0)51 430 2708 Email: [email protected]

Cape Town Campus

The Brookside Building, 11 Imam Haron Str (old Lansdowne Road), Claremont P.O. Box 2325, Clareinch, 7740 Tel: +27 (0)21 674 6567, Fax: +27 (0)21 674 6599 Email: [email protected]

Durban Campus

1 Lunar Row, Umhlanga Ridge, Durban

P.O. Box 20251, Durban North, 4016 Tel: +27 (0)31 564 0570/5, Fax: +27 (0)31 564 8978 Email: [email protected]

Durbanville Campus

Kaapzicht, 9 Rogers Street, Tyger Valley P.O. Box 284, Private Bag X7

Tyger Valley, 7536 Tel: +27 (0)21 914 8000, Fax: +27 (0)21 914 8004 Email: [email protected]

East London Campus

12 Stewart Drive, Berea, East London PostNet Suite 373

Private Bag X9063, East London, 5200 Tel: +27 (0)43 721 2564, Fax: +27 (0)43 721 2597 Email: [email protected]

Nelspruit Campus 50 Murray Street, Nelspruit P.O. Box 9497, Sonpark, Nelspruit, 1206 Tel: +27 (0)13 755 3918, Fax: +27 (0)13 755 3918 Email: [email protected]

Port Elizabeth Campus

Building 4, Ascot Office Park Cnr Ascot & Conyngham Roads, Greenacres P.O. Box 40049, Walmer, 6065 Tel: +27 (0)41 374 7978, Fax: +27 (0)41 374 3190 Email: [email protected]

Potchefstroom Campus

12 Esselen Street, Cnr Esselen Street & Steve Biko Avenue, Die Bult, Potchefstroom P.O. Box 19900, Noordbrug, 2522 Tel: +27 (0)18 297 7760, Fax: +27 (0)18 297 7783 Email: [email protected]

Pretoria Campus

22 Umgazi Street, Menlo Park, Pretoria PostNet Suite A147, Private Bag X18, Lynnwood Ridge, 0040 Tel: +27 (0)12 348 3060, Fax: +27 (0)12 348 3063 Email: [email protected]

Randburg Campus

6 Hunter Avenue, Cnr Bram Fischer Drive Ferndale, Randburg P.O. Box 920, Randburg, 2125 Tel: +27 (0)11 789 3178, Fax: +27 (0)11 789 4606 Email: [email protected]

Vanderbijlpark Campus

Building 2, Cnr Rutherford & Frikkie Meyer Boulevards Vanderbijlpark P.O. Box 6371, Vanderbijlpark, 1900 Tel: +27 (0)16 931 1180, Fax: +27 (0)16 933 1055 Email: [email protected]

Group Head Office

Management Services Building 44 Alsatian Road, Glen Austin Extension 3, Midrand P.O. Box 1398, Randburg, 2125 Tel: +27 (0)11 467 8422, Fax: +27 (0)86 583 6660 Website: www.cti.ac.za

CTI is part of Pearson, the world’s leading learning company. Pearson is the corporate owner, not a registered

provider nor conferrer of qualifications in South Africa. CTI Education Group (Pty) Ltd. is registered with the Department of Higher Education and Training as a private higher education institution under the

Higher Education Act, 101, of 1997. Registration Certificate number: 2004/HE07/004. www.cti.ac.za.

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