CompTIA A+ Certification Essentials Support Skills (2009 Objectives with Windows 7)

CompTIA A+ Certification Essentials Support Skills

(2009 Objectives with Windows 7)

Study Notes

G180eng ver091

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Acknowledgements

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Study Notes Table of Contents

Page iii

Table of Contents

Course Introduction i

Table of Contents ............................................................................................................. iii About This Course .......................................................................................................... viii

Module 1 / PC and Laptop Hardware 1

Module 1 / Unit 1 Types of Computer 3

Personal Computers .......................................................................................................... 3 Desktop Computers ........................................................................................................... 6 Portable Computers ......................................................................................................... 10 Units, Signaling, and Circuits ........................................................................................... 14

Module 1 / Unit 2 Motherboards 20

Motherboard Layout ........................................................................................................ 21 Bus Architecture .............................................................................................................. 22 Motherboard Components ............................................................................................... 23 Expansion Bus and Adapter Cards .................................................................................. 27 Motherboard Form Factors .............................................................................................. 35 Power Supply Unit (PSU) ................................................................................................ 39 Cooling Systems ............................................................................................................. 45

Module 1 / Unit 3 Processors 50

Central Processing Unit (CPU) ........................................................................................ 50 Features of CPUs ............................................................................................................ 52 Intel Processors ............................................................................................................... 60 AMD Processors ............................................................................................................. 63 CPU Packaging ............................................................................................................... 64 Laptop Processors........................................................................................................... 68

Module 1 / Unit 4 Memory 70

Memory Types ................................................................................................................. 70 Memory Characteristics ................................................................................................... 76

Module 1 / Unit 5 Storage Devices 80

Storage Devices .............................................................................................................. 80 Hard Drives ..................................................................................................................... 81 Drive Controllers .............................................................................................................. 83 Floppy Drives .................................................................................................................. 90

Course Introduction CompTIA A+ Certification Essentials Support Skills

Page iv

Optical Disc Storage ........................................................................................................ 91 Flash Memory .................................................................................................................. 96 Tape Drives ..................................................................................................................... 98

Module 1 / Unit 6 Input and Peripheral Devices 101

I/O Ports and Cables ..................................................................................................... 102 Input Devices ................................................................................................................. 109 I/O Devices .................................................................................................................... 115 Communications Devices .............................................................................................. 120 Installing and Configuring Peripherals ........................................................................... 123

Module 1 / Unit 7 Video and Sound Devices 128

Display Devices ............................................................................................................. 128 Video Adapters .............................................................................................................. 136 Audio Devices ............................................................................................................... 141 Multimedia Input Devices............................................................................................... 145

Module 1 / Summary PC and Laptop Hardware 149

Module 2 / Operating Systems 153

Module 2 / Unit 1 Windows Operating System 155

What is an Operating System? ...................................................................................... 155 Windows Architecture .................................................................................................... 156 Early Versions of Windows ............................................................................................ 163 Windows 2000 ............................................................................................................... 164 Windows XP .................................................................................................................. 168 Windows Vista ............................................................................................................... 174 Windows 7 ..................................................................................................................... 181

Module 2 / Unit 2 Managing Windows 187

Windows Administrative Tools ....................................................................................... 187 Configuring Hardware .................................................................................................... 202 Screen Savers and Power Management ....................................................................... 210 Managing Software........................................................................................................ 215 Managing Services ........................................................................................................ 220 Windows Registry .......................................................................................................... 222

Module 2 / Unit 3 Windows Storage Management 226

Preparing a Hard Disk ................................................................................................... 226 Navigating Windows ...................................................................................................... 230


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Working with Folders ..................................................................................................... 236 Working with Files ......................................................................................................... 238 Searching For Files ....................................................................................................... 243 The Recycle Bin ............................................................................................................ 245 File and Folder Management in Vista ............................................................................ 247 File and Folder Management in Windows 7 ................................................................... 249

Module 2 / Unit 4 Installing and Upgrading Windows 253

Overview of OS Installations .......................................................................................... 253 Installing Windows from CD / DVD ................................................................................ 259 Upgrading Windows ...................................................................................................... 265 Options for Deploying Windows ..................................................................................... 273

Module 2 / Unit 5 Windows Boot Process 278

Windows Boot Process .................................................................................................. 278 The BOOT.INI File ......................................................................................................... 282 Windows Vista/7 Boot Process ...................................................................................... 284 Configuring Boot Devices .............................................................................................. 286 Advanced Startup Options ............................................................................................. 287

Module 2 / Summary Operating Systems 293

Module 3 / Networking and Printing 295

Module 3 / Unit 1 Network Concepts 296

What is a Network? ....................................................................................................... 296 The OSI Model .............................................................................................................. 303 Network Components .................................................................................................... 304 TCP/IP ........................................................................................................................... 309 Internet Protocol and IP Addressing .............................................................................. 310 TCP/IP Application Protocols ......................................................................................... 317 NetBIOS and NetBEUI .................................................................................................. 322 Virtual Private Networks ................................................................................................ 323 The Internet ................................................................................................................... 324

Module 3 / Unit 2 Local, Wireless, and Remote Networks 330

Network Cabling ............................................................................................................ 330 Wireless Networks ......................................................................................................... 335 Windows Networking ..................................................................................................... 341 Simple File Sharing and Homegroups ........................................................................... 343 Accessing the Internet ................................................................................................... 348


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Module 3 / Unit 3 Printers 357

Windows Print Process .................................................................................................. 357 Printer Types ................................................................................................................. 360 Installing and Configuring a Printer ................................................................................ 371 Maintaining Printers ....................................................................................................... 380

Module 3 / Summary Networking and Printing 383

Module 4 / PC Support 385

Module 4 / Unit 1 Troubleshooting Techniques 387

Troubleshooting Models and Processes ........................................................................ 387 Approaching Troubleshooting ........................................................................................ 395 Troubleshooting Resources ........................................................................................... 398

Module 4 / Unit 2 Basic Troubleshooting Scenarios 402

Troubleshooting Basic Hardware Problems ................................................................... 402 Troubleshooting Windows Errors ................................................................................... 408 Troubleshooting Applications ......................................................................................... 411 Troubleshooting Printers ............................................................................................... 413 Network Troubleshooting Basics ................................................................................... 416

Module 4 / Unit 3 Preventative Maintenance 422

Health and Safety .......................................................................................................... 422 Physical Inspections ...................................................................................................... 430 Maintaining and Optimizing Drives ................................................................................ 433 Environment .................................................................................................................. 437 Patch Management ....................................................................................................... 444 Data Backup .................................................................................................................. 450 Disposal of Consumables and Computer Equipment ..................................................... 456

Module 4 / Unit 4 Security 460

Security Fundamentals .................................................................................................. 460 Access Control .............................................................................................................. 462 Authentication ................................................................................................................ 470 Accounting .................................................................................................................... 473 Social Engineering......................................................................................................... 473 Malware ......................................................................................................................... 474 Data Security ................................................................................................................. 478


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Module 4 / Unit 5 Professionalism and Communication 483

Customer Service Skills ................................................................................................. 483 Communication Skills .................................................................................................... 484 Professionalism ............................................................................................................. 488 Handling Customer Complaints ..................................................................................... 495

Module 4 / Summary PC Support 500

Index 503


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About This Course

This course is intended for students wishing to qualify with CompTIA A+ Certification. A+ certification is designed to help students become entry-level IT technicians. It covers preventative maintenance, basis networking, installation, troubleshooting, communication skills, and professionalism.

What are the Course Prerequisites?

Ideally, you should have successfully completed gtslearning's "PC Fundamentals with CompTIA Strata" course or have some basic experience of using a PC, Windows, and browsing the web. Specifically, it is recommended that you have the following skills and knowledge before starting this course:

Use a keyboard and mouse.

Recognise the main components of a PC and different data media such as floppy disks, or CD-ROMs.

Start the computer and navigate the desktop.

Use Windows Explorer to create directories and subdirectories; and move, copy or rename files and directories.

Use Internet Explorer to view websites.

Optionally, you can take a prerequisites test to check that you have the knowledge required to study this course at www.gtssupport.com/flower27/220-701/index.htm.

Course Outcomes

This practical "hands-on" course will teach you the fundamental principles of supporting desktop and portable computers and operating systems. This course will teach you how to install, maintain, and troubleshoot computer components and systems. As a PC technician, you will be expected to support old and new systems, so it is important that you have a full understanding of legacy hardware and software, as well as the latest technologies.

On course completion, you will be able to:

Identify types and characteristics of PC components, including motherboard, CPU, memory, and storage, input, and output devices.

Install and configure peripheral devices.

Identify types and characteristics of portable computers.

Install and configure Microsoft Windows 2000, Microsoft Windows XP, Microsoft Windows Vista, and Microsoft Windows 7.

Study Notes About This Course

Page ix

Perform basic PC maintenance and troubleshooting.

Understand fundamental principles of securing IT systems and working safely.

Communicate effectively with customers.

Install and configure print devices.

Understand fundamental principles of implementing LANs and internet access.

How Certification Helps Your Career

The main aim of this course is to help to prepare you for CompTIA's A+ Certification Essentials exam (exam code 220-701).

To obtain CompTIA A+ Certification, you must pass both the Essentials exam and the Practical Application exam (220-702). You must complete the Practical Application Support Skills course to prepare for the second exam.

Certification proves you have the knowledge and skill to solve business problems in virtually any business environment. Certifications are highly valued credentials that qualify you for jobs, increased compensation, and promotion.

CompTIA A+ certification held by many IT staff in organisations. Worldwide, more than 800,000 individuals are CompTIA A+ certified and 31% of IT staff within a random sampling of US organisations within a cross section of industry verticals hold A+ Certification.

Indeed, A+ Certification is often a prerequisite qualification for employment and is mandated or recommended by many leading computer manufacturers and vendors, such as Cisco and HP and Ricoh, the US State Department, and US government contractors such as EDS, General Dynamics, and Northrop Grumman.

IT is Everywhere

IT is ubiqitous; a critical

requirement of most

organizations. Globally, there are over 600,000 IT job openings.

IT Knowledge and Skills Gets

Jobs

Certifications are essential

credentials that qualify you for jobs, increased compensation, and promotion.

Retain your Job and Salary

Make your expertise stand above the rest. Competence is usually retained during times of

change.

Want to Change Jobs?

Certifications qualify you for

new opportunities, whether you see

limited advancement in your current job or need to change

careers.

Stick Out from the Resume Pile

Hiring managers can demand the strongest skill set.


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CompTIA Career Pathway

Completing this course will help you to pursue a career in ICT. This course will particularly benefit you in pursuing a career in supporting desktop personal computer users, in job roles such as Support Engineer, Maintenance Engineer, Desktop Engineer, Computer Administrator, or PC Support Analyst.

CompTIA offers a number of credentials that form a foundation for your career in technology and allow you to pursue specific areas of concentration. Depending on the path you choose to take, CompTIA certifications help you build upon your skills and knowledge, supporting learning throughout your entire career.

Study of the course can also help to prepare you for other, similar technical support qualifications and act as groundwork for more advanced training. Other qualifications available include:

CompTIA Network+ - a foundation-level certification of competency in network installation and configuration.

CompTIA Server+ - validates the skills of advanced IT technicians (individuals with 18-24 months' experience with Industry Standard Server Architecture [ISSA]).

CompTIA Security+ - validates knowledge of communication security, infrastructure security, cryptography, operational security, and general security concepts.


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Cisco Certified Network Associate (CCNA) - a foundation-level certification of competency in Cisco networking appliance installation and configuration.

Microsoft Certified Systems Administrator / Engineer / IT Professional (MCSA / MSCE / MCITP) - Windows-specific qualifications; passing CompTIA's A+, Network+, and either Server+ or Security+ Certification can satisfy the requirements for the elective part of the certification, as well as providing a solid groundwork for the further study required for MCSA / MCSE (Windows Server 2003 track) or MCITP (Windows Server 2008 Server Administrator / Enterprise Administrator track).

Other corporations such as Novell, HP, CompuCom, and Ricoh also recognise CompTIA A+ as part of their certification tracks or require that their service technicians obtain the certification.

Help Desk Support Analyst - The Help Desk Analyst certification series, administered by the Help Desk Institute (www.thinkhdi.com), certifies learners' customer service and Help Desk management skills. Various levels of certification are available, including Customer Support Specialist, Help Desk Analyst and Help Desk Manager.

About the Course Material

The course material has been prepared as an aid for your use throughout the training course. You may keep this manual for your own reference after the course is finished. We hope you will find the course material useful for future reference.

The course comes in two parts. This "Study Notes" volume contains the main text of the book for you to refer to in class and to review at home as you prepare for the exam. The course text is divided into several modules, each covering a different subject area. Each module is split into a series of units containing related topics for study. Each unit has a set of review questions designed to test your knowledge of the topics covered in the unit.

At the back of the "Study Notes" volume there is an index to help you look up key terms and concepts from the course.

The accompanying "Labs and References" book contains a list of the CompTIA certification objectives (and where in the study notes you can find useful material to prepare for each objective), tips for taking the CompTIA exams, the practical labs for you to complete in class, answers to the end of unit review questions, and a glossary of terms and concepts used in computer support.

If you are viewing this course as an ebook, the "Labs and References" volume is located after the index - use the bookmarks panel to navigate between sections.

When you have completed the course and want to prepare for the exam, you can take a practice test at www.gtssupport.com/flower27/220-701/index.htm.


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Video Training

gtslearning and Professor Messer are excited to announce a joint effort in interactive learning for CompTIA's certification courses.

Professor Messer uses gtslearning's CompTIA certification courseware to develop and record his popular video training sessions. Now you can easily follow along with his video presentations using the links provided in the margins of this course book.

You can use the links in three ways:

1) If you have an ebook, just click the link to open the video in your browser.

2) If you have a QR code scanner, point your camera at the code to open it in your phone or tablet's browser.

gtsgo.to/1q3xc

3) If you have a printed book but no scanner, enter the web address into your browser.

We do endeavour to keep the video links up-to-date, but if you come across a broken link, please email the link code (for example "1g3xc") to [email protected] and we will update it.

Course Conventions and Icons

The following conventions have been used in this course. These are especially useful for following the practical lab exercises.

Bullet and number lists - steps for you to follow in the course of completing a task or hands-on exercise and review questions are indicated by numbered bullet points. Other bullet points indicate learning objectives and feature lists.

File and command selection - in the labs, files, applets, dialogs and other information that is displayed on the screen by the computer is shown in sans serif bold. For example: Click OK, Select Control Panel, and so on.

Sequences of commands - in the labs, a sequence of steps to follow to open a file or activate a command are shown in bold with arrows. For example, if you need to access the system properties in Windows, this would be shown in the text by: Start > Control Panel > System.

Commands - commands or information that you must enter using the keyboard are shown in Courier New Bold. For example: Type [email protected]. Courier New Bold-Italic represents some sort of variable, such as your student number. For example, if your student number is "5", you would follow the instruction ping 10.0.0.x by entering ping 10.0.0.5.


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Using the mouse - when instructed to click, use the main mouse button; when instructed to alt-click, use the secondary button (that is, the button on the right-hand side of the mouse, assuming right-handed use). Sometimes you need to use both the keyboard and the mouse - for example, Ctrl+click means hold down the Ctrl key and click the main mouse button.

The following symbols are used to indicate different features in the course book:

Icon Meaning

A tip or warning about a feature or topic.

A reference to another unit, where more information on a topic can be found.

A link to a Professor Messer video presentation. Click or use a QR scanner to open the link or enter the address printed below it.

Space for you to make your own notes.

Review questions to help test what you have learned.

A hands-on exercise for you to practise skills learned during the lesson.

Content Seal of Quality

This courseware bears the seal of CompTIA Official Approved Quality Content. This seal signifies this content covers 100% of the exam objectives and implements important instructional design principles. CompTIA recommends multiple learning tools to help increase coverage of the learning objectives.

The contents of this training material were created for the CompTIA A+ Certification Essentials exam (exam code: 220-701) covering version 2.0 of the 2009 Edition A+ CompTIA certification exam objectives.


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It is CompTIA's policy to update the exam regularly with new test items to deter fraud and for compliance with ISO standards. The exam objectives may therefore describe the current "Edition" of the exam with a date different to that above. Please note that this training material remains valid for the stated exam code, regardless of the exam edition. For more information, please check the FAQs on CompTIA's website (support.comptia.org).

Four Steps to Getting Certified

This training material can help you prepare for and pass a related CompTIA certification exam or exams. In order to achieve CompTIA certification, you must register for and pass a CompTIA certification exam or exams.

In order to become CompTIA certified, you must:

1) Review the certification objectives at www.comptia.org/certifications/testprep/examobjectives.aspx to make sure you know what is covered in the exam.

2) After you have studied for the certification, take a free assessment and sample test from CompTIA at www.comptia.org/certifications/testprep/practicetests.aspx to get an idea what type of questions might be on the exam. You can also use gtslearning's free practice tests at www.gtssupport.com/flower27/220-701/index.htm.

3) Purchase an exam voucher on the CompTIA Marketplace, which is located at www.comptiastore.com.

4) Select a certification exam provider and schedule a time to take your exam. You can find exam providers at www.comptia.org/certifications/testprep/testingcenters.aspx

How to Obtain More Information

Visit CompTIA online - www.comptia.org to learn more about getting CompTIA certified.

Contact CompTIA - call 866-835-8020 ext. 5 or email [email protected].

Connect with CompTIA : .

Join the IT Pro Community - visit itpro.comptia.org to join the IT community to get relevant career information.

No part of these notes may be reproduced in any form, electronic or printed, without the written permission of a director of gtslearning International Limited. If you suspect that these notes have been unlawfully copied, please telephone +44 (0)207 887 7999 or email [email protected]

Study Notes PC and Laptop Hardware

Page 1

Module 1 / PC and Laptop Hardware

A+ Certification Essentials Domain Areas % of

Examination

1.0 Hardware 27% 2.0 Troubleshooting, Repair, and Maintenance 20% 3.0 Operating System and Software 20% 4.0 Networking 15% 5.0 Security 8% 6.0 Operational Procedure 10%

Unit Domain Objectives / Examples

1.1 Types of Computer

This unit does not cover any specific CompTIA A+ objectives or content examples.

1.2 Motherboards

1.2 Explain motherboard components, types and features Form Factor (ATX / BTX, micro ATX, NLX) • Memory slots (RIMM, DIMM, SODIMM, SIMM) • Processor sockets • Bus architecture • Bus slots (PCI, AGP, PCIe, AMR, CNR) • Chipsets • BIOS / CMOS / Firmware (POST, CMOS battery) • Riser card / daughterboard 1.3 Classify power supplies types and characteristics AC adapter • ATX proprietary • Voltage, wattage and capacity • Voltage selector switch • Pins (20, 24) 1.5 Explain cooling methods and devices Heat sinks • CPU and case fans • Liquid cooling systems • Thermal compound 1.10 Install, configure and optimise laptop components and features Power and electrical input devices (Auto-switching, Fixed input power supplies, Batteries)

1.3 Processors

1.4 Explain the purpose and characteristics of CPUs and their features Identify CPU types (AMD, Intel) • HyperThreading • Multi core (Dual core, Triple core, Quad core) • On-chip cache (L1, L2) • Speed (real vs. actual) • 32-bit vs. 64-bit

1.4 Memory 1.6 Compare and contrast memory types, characteristics and their purpose Types (DRAM, SRAM, SDRAM, DDR / DDR2 / DDR3, RAMBUS) • Parity vs. Non-parity • ECC vs. non-ECC • Single sided vs. double sided • Single channel vs. dual channel • Speed (PC100, PC133, PC2700, PC3200, DDR3-1600, DDR2-667)

No part of these notes may be reproduced in any form, electronic or printed, without the written permission of a director of gtslearning International Limited. If you suspect that these notes have been unlawfully copied,

please telephone +44 (0)207 887 7999 or email [email protected]

Module 1 / Unit 1 CompTIA A+ Certification Essentials Support Skills

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Unit Domain Objectives / Examples

1.5 Storage Devices

1.1 Categorise storage devices and backup media FDD • HDD (Solid state vs. magnetic) • Optical drives (CD / DVD / RW / Blu-Ray) • Removable storage (Tape drive, Solid state [e.g. thumb drive, flash, SD cards, USB], External CD-RW and hard drive, Hot swappable devices and non-hot swappable devices) 1.2 Explain motherboard components, types and features PATA (IDE, EIDE) • SATA, eSATA • Contrast RAID (levels 0, 1, 5)

1.6 Input and Peripheral

Devices

1.2 Explain motherboard components, types and features I/O interfaces (Sound, Video, USB 1.1 and 2.0, Serial, IEEE 1394 / Firewire, Parallel, NIC, Modem, PS/2) • Bus slots (PCMCIA) 1.8 Install and configure peripherals and input devices Mouse • Keyboard • Barcode reader • Biometric devices • Touch screen • KVM switch 1.9 Summarise the function and types of adapter cards I/O (SCSI, Serial, USB, Parallel) • Communications (NIC, Modem) 1.10 Install, configure and optimise laptop components and features Expansion devices (PCMCIA cards, PCI Express cards, Docking station) • Communication connections (Bluetooth, Infrared, Cellular WAN, Ethernet, Modem) • Input devices (Stylus / digitizer, Function keys, Point devices [e.g. touch pad, point stick / track point])

1.7 Video and Sound

Devices

1.7 Distinguish between the different display devices and their characteristics Projectors, CRT and LCD • LCD technologies (Resolution [e.g. XGA, SXGA+, UXGA, WUXGA], Contrast ratio, Native resolution) • Connector types (VGA, HDMi ,S-Video, Component / RGB, DVI pin compatibility) • Settings (Refresh rate, Resolution, Multi-monitor, Degauss) 1.8 Install and configure peripherals and input devices Multimedia (e.g. web and digital cameras, MIDI, microphones) 1.9 Summarise the function and types of adapter cards Video (PCI, PCIe, AGP) • Multimedia (Sound card, TV tuner cards, Capture cards)


Study Notes Types of Computer

Page 3

Module 1 / Unit 1 Types of Computer

Objectives

On completion of this unit, you will be able to:

Identify the components that make up a personal computer.

Distinguish desktop, laptop, and PDA types of computer.

Understand the basic principles of data units, electrical circuits, and signalling types.

Personal Computers

The term "Personal Computer" is generally understood to apply to versions of the IBM PC, developed in 1981. The IBM PC was based on a microprocessor (or Central Processing Unit [CPU]) designed by Intel. This is also called the x86 architecture or platform.

While technologies and performance have completely transformed what we know as PCs from the boxes available in 1981, most desktop computers are still based on the IBM PC design and x86 platform.

As this PC platform matured, it came to be associated with use of Microsoft's Windows operating system software. Now, hardware and software development for PCs is often done with Windows compatibility in mind.

Mainstream PCs were developed as business machines, with the home computer market dominated by cheaper versions of the microcomputer. Through the 1990s, cost and ease-of-use improved to the point where PCs are mainstream consumer devices used in business, education, and the home.

gtsgo.to/j8k37




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Key Functions of a PC

PCs use hardware and software components. Hardware components are often classed according to usage (input, output, storage, processing, or network/communications). Software components include the operating system and applications.

Input - entry of raw data; for example, typing names and addresses on a keyboard or transmitting a picture from a digital camera.

Processing - manipulation of the raw data to produce useful information, the key purpose of a computer; for example, sorting or indexing the names and addresses or adding effects to the picture.

Output - transformation of the data into information, perhaps in a non-computerised format; for example, printing mailing labels from a database or displaying the picture in a brochure.

Storage - retention of the data until it is needed; for example, filing names and addresses in a database or archiving the picture in an online library.

With a basic understanding of these key functions, the role of each of the components of a PC becomes much clearer.

1

2

3

45

6 7

HP Pavilion computer system

# Component Function

1 System Unit Contains processing components and hard disk storage

2 DVD and floppy disk drives

Removable storage

3 Flat panel display Output

4 Keyboard Input

5 Mouse Input

6 Speakers Output

7 Printer Output



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A good way to understand the functions of the different components of the PC is to think of them working as interfaces. Input and output hardware devices provide an interface between the user and the computer; the operating system provides an interface between hardware components and software applications.

Essentially, a PC works as follows:

1) When a user selects a command (perhaps using a mouse to click an icon on the application toolbar), the software application receives the command and, using the functions of the operating system, converts it into a series of instructions, which are stored in system memory.

2) The CPU retrieves each instruction from memory and processes it.

3) The CPU then writes the result back to memory and directs other components to perform actions (for example, it may instruct the display subsystem to update the image shown to the user or the storage subsystem to save data to a disk).

A PC can process millions of instructions per second, which gives it the illusion of being able to "think".

PC Vendors

PCs are a fully commoditised product, meaning that margins are low and vendors must achieve market share by differentiating on support and customer service and profitability by leveraging economies of scale.

While there are many vendors serving local and special interest markets, globally PC manufacture is dominated by Dell, Hewlett-Packard (HP)/Compaq, Lenovo (previously IBM's PC division), Acer, and Fujitsu/Siemens with Sony, Toshiba, and ASUS also strong in the laptop market.

Another personal computer vendor, Apple, ship Macintosh computers with a different operating system (Apple Mac OS) and (up until 2006) a different hardware platform to the IBM PC-compatible vendors.




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Desktop Computers

"Desktop computer" refers to a PC that is not designed to be used on the move.

The components of a desktop computer system are divided between those that are designed to be handled by the user (peripheral devices) and those that would be damaged or dangerous if exposed.

The system case is a plastic and metal box that houses this second class of components, such as the motherboard, CPU, memory, adapter cards, disk drives, and power supply unit.

System Case Types

There are three basic types of system case (or chassis): Desktop, Tower, and Small Form Factor (SFF). All these types are available in different sizes.

Be aware that while a small case may be desirable because it takes up less space, it has less room inside for installing extra devices and is less effective at cooling.

Up until a few years ago, PC cases were uniformly beige. As PCs are becoming integrated in home entertainment and companies become more image conscious about their office space, sleek black or chrome has become the preferred look.

Desktop Case

A desktop case is designed to sit horizontally on a surface, so that it is wider than it is tall. If turned on its side, a CD-ROM or DVD tray would be oriented incorrectly. These are usually used for office or home PCs. Desktop cases come in two basic sizes: standard and slimline.

Tower Case

A tower case is designed to sit vertically on a surface, so that it is taller than it is wide. Tower cases come in three basic sizes: full, midi, and mini.

Full-tower cases are usually used for PC servers - these require the extra internal space for additional hard disks, adapter cards, and redundant power supply units.



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Midi-tower cases are used for high-end user PCs. These PCs do require extra devices and adapter cards, but not as many as a server.

HP Compaq Proliant tower case (cover removed) showing 1) Motherboard;

2) Expansion slots; 3) Power supply; 4) 5.25" Drive bays; 5) Floppy disk drive bay; 6) 3.5" Drive bays (for hard drives)

Mini-tower cases are usually used for office or home PCs where the requirement for additional internal devices and adapter cards is limited.

Small Form Factor

SFF case designs are semi-portable, space-saving designs typically used for domestic entertainment "Media Center" systems that will not look out of place in a living room. They are usually cube-like or super slimline. SFF cases can only fit a limited number of components.

Shuttle XPC

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2

3 4

5

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Parts of the Case

The case has a cover, which is removed by either undoing the screws at the back or pressing together clips that release it. Cases based on the slimline design have a hinged cover that releases to allow access to the motherboard.

Some cases feature tool-free access (that is, they are secured by clips). Some cases use proprietary screw fittings (to prevent unauthorised access to the internal components).

The front panel provides access to the floppy and CD, a power on/off switch, a reset switch, and LEDs (Light Emitting Diodes) 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 or clips that secure it.

This figure shows the front panel of a PC:

1) CD-RW and CD-ROM drives (in 5" bays").

2) Spare 5" bays.

3) 3.5" floppy disk drive.

4) Flash memory card reader.

5) USB ports.

6) Video and audio input and output jacks.

7) Firewire port.

8) Power on/off switch.

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Front Panel of HP Pavilion



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The rear panel has slots through which adapter card connectors appear. These slots should either be covered by an adapter card or a metal strip known as a blanking plate (uncovered slots can disrupt the proper flow of air around components in the PC and cause overheating and also increase the amount of dust in the system).

There are also slots through which the motherboard connectors appear - such as parallel and serial port connectors. The rear panel provides access to the Power Supply Unit (PSU) sockets. The PSU has an integral fan exhaust - care should be taken that it is not obstructed, as this will adversely affect cooling.

1) Power Supply Unit with fan.

2) Chassis fan.

3) Motherboard I/O ports.

4) Expansion card slots (covered by blanking plates).

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Rear Panel of HP Compaq

System Case Designs

It is important to note that there are different system case design specifications to accommodate different motherboards and power supplies. If you are building a PC, you must make sure that you buy a matching case, motherboard, and power supply.

Most PCs are based on the ATX case and power supply standard, but there are proprietary designs too, especially where SFF PCs are concerned.




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Portable Computers

The market for portable computers is one of the faster growing areas of IT. There are three main types of portable technology, categorised in ascending order of size:

Handheld devices - including Personal Data Assistants (PDA) and Smartphones (mobile phones with PDA functionality). These devices are a few inches in size and weigh only a few ounces (or a few hundred grams).

Tablet PCs - larger than handhelds but operated using a touchscreen rather than a pointing device and keyboard.

Laptops/Notebooks - still coming in a range of sizes, but closest to the functionality of a desktop PC.

Laptops are eating into the market share enjoyed by desktop PCs, driving prices closer and closer. Most vendors expect to sell more laptops than desktops within a few years. Another important driver is network convergence. This means use of the same network to deliver different types of communications (voice, video, data, and so on). Portable devices commonly integrate the functions of phone, TV, radio, and computer.

HP ProBook laptop computer with 1) Built-in screen; 2) Integrated keyboard; 3) Touchpad pointer control; 4) I/O ports [on both sides and rear of chassis]

The main features distinguishing portable computers from desktop PCs are:

Size and weight - laptops weigh between around 2 and 4kg (4.5 - 9lbs) and handhelds even less.

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Display type - portable computers use flat-panel display technologies to provide lightweight, slimline display screens that are integrated with the chassis.

Input devices - the main input devices are integrated into the unit, such as a built-in keyboard, touchpad instead of mouse, or touchscreen.

Cost - laptops cost from 1½-2x as much as a similarly-specified desktop computer. Handhelds can cost as much as a low-end desktop, despite having much less functionality.

Power source - portable computers can be run from internal battery packs.

Components - portables often use different components that are smaller, lighter, and draw less power than desktop versions (notably the CPU). Laptop design is not as well standardised as desktop, with more use of proprietary components.

Types of Laptop

Like desktops, laptops come in many different models and specifications. You could broadly categorise laptops as follows:

Entry Level / Budget - basic model (often with home or business versions) featuring average components and a happy tradeoff between features and portability.

Desktop Replacement - a powerful machine with similar performance, capacity, and peripherals to a desktop PC. The trade off is that these machines are less portable and less able to run for a long period on battery power.

Ultra Portable - very small and light machines offering extended operating time on battery power. The trade off here is smaller screen size, lower capacity drives, and fewer peripherals.

Media Center - portable home entertainment systems, featuring large screens, storage capacity, media features (such as TV tuner, video recording, and surround sound), and components capable of running the latest games.

Gaming Laptop - an increasingly popular class of machine. ATI and nVIDIA are producing more graphics adapters designed for laptops though they cannot match the power of desktops built for gaming.




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Tablet PC

A tablet PC (or slate) is similar to an ultra portable laptop but has a touch sensitive screen that supports handwriting recognition. This makes the device ideal for professions where note-taking is important (doctors, nurses, teachers, scientists, and so on).

HP Compaq Tablet PC

A tablet PC may come with a keyboard (typically the screen is attached with a hinge) or may require a USB keyboard. Windows XP Tablet PC Edition and all versions of Windows Vista/7 are designed to support the input features of tablets.

Personal Digital Assistants (PDAs)

HP iPAQ smartphone running

Windows Mobile

A PDA is an instant-access miniature computer, but PDAs are not as versatile as laptops or tablets. Only software designed specifically for the mobile operating system can be installed. Laptops, however, can use the same software as your desktop computer.

Some PDAs use Windows Mobile (or Pocket PC), and so provide a familiar user interface. Other machines use their own proprietary operating system; for example, the Palm and HandSpring series of PDAs, which use Palm OS.



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Increasingly, PDA functionality is being integrated with mobile phones, called Smartphones. As well as Windows Mobile, the Apple iPhone OS, RIM BlackBerry and Symbian OS are used for these devices.

Netbook

Netbooks fit between traditional laptops and PDAs. Just as laptops have consumed a large part of the desktop market share, netbooks are starting to consume laptop market share. Unlike laptops, they only have limited functionality and performance (typically restricted to running two or three applications simultaneously) but unlike PDAs they have a full keyboard, touchpad, and large (7-9") screen.

HP Mini 1000 netbook

Netbooks are designed primarily for internet access and communications. While they can run standard desktop / laptop operating systems and software, they are often used to access web hosted software (referred to as cloud computing) rather than locally-installed applications.




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Units, Signalling, and Circuits

You need to understand the terminology and units used to describe computer storage, signalling, and networking and the properties of electrical signalling and circuits.

Data Units

The following notes will help you to understand binary and hexadecimal notation and the terms used to speak about data size values.

Computers work with binary data. The fundamental unit of data storage is the 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 sizes memory capacity, and disk storage capacity

8 bits form a byte (B).

1024 bytes make a kilobyte (that is 2 ^ 10 bytes).

1024 kilobytes (KB) make a Megabyte (MB) or 1,048,576 bytes.

1024 MB make 1 Gigabyte (GB) or 1,073,741,824 bytes.

1024 GB make 1 Terabyte (TB).

The units listed above conflict with the SI labels for unit multiples. Under the SI system, kilo should mean 1,000, mega should mean 1,000,000, and giga should mean 1,000,000,000. The use of KB to mean 1,204 or GB to mean 1,073,741,824 is shorthand used only in the PC industry.

To try to clear this up, a system of labels for binary units has been devised (kibibyte [KiB], mebibyte [MiB], and gibibyte [GiB]). In practice however, no part of the computer industry has taken this distinction on board. Therefore the old units have been used throughout this course book and will be the ones used in the A+ exams. Consequently, you should understand what is generally meant by terms such as MB and GB in different contexts.

File sizes and memory capacity are always quoted as binary measurements. For example, when you see that Windows reports 2 GB memory, this means 2048 MB, not 2000 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 GiB.



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You also need to be familiar with values used to talk about transferring data between components or over a network. Data transfer rates are recorded as units per second; for example, bit per second (bps), Megabits per second (Mbps), Megabytes per second (MBps), or Gigabytes per second (GBps). When used to speak about network transfer rates, kilo, mega, and giga are decimal measurements. For example, 56 Kbps means 56,000 bits per second not 57,344 bits per second.

Binary and Hexadecimal Notation

It is often necessary to refer to memory or network addresses. To a computer, these addresses are represented as binary values but because binary has only two values for each position and the values are typically very large, this would require a long string of characters to write out. This is difficult enough to read but even harder to type accurately into configuration dialogs.

Binary values are often converted to decimal but hexadecimal notation is another convenient way of referring to long binary strings. Hexadecimal has 16 characters (0...9 plus A, B, C, D, E, F). Therefore it only takes 1 hexadecimal character to represent 4 binary characters.

For example, the memory address for the component COM2 (a serial port) is 02F8. In binary, this is 0000 0010 1111 1000. Hex notation is therefore much more compact.

The following table summarises the equivalent representations of decimal values from 0-15 in binary and hex.

Decimal Hexadecimal Binary Decimal Hexadecimal Binary

0 0 0000 8 8 1000

1 1 0001 9 9 1001

2 2 0010 10 A 1010

3 3 0011 11 B 1011

4 4 0100 12 C 1100

5 5 0101 13 D 1101

6 6 0110 14 E 1110

7 7 0111 15 F 1111




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Signalling

Another subject you need to understand is how PC components exchange information. Computers transmit data using electrical signals and store it using components called transistors. The electrical pathways within the computer or through cabling that carry the signals are referred to as the bus. However, numerous different bus technologies have been and are used to build computers. Also, there are many different signalling methods.

Generally speaking, older computer bus types (such as serial and PS/2 ports or VGA display connectors) 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 the use of lower voltages, reducing power consumption and heat.

Another distinction between signalling methods is between parallel and serial communications. Some bus types transfer data in parallel, which means that there are multiple physical wires to carry the signals. A parallel bus 32 bits wide would transfer 32 bits in each operation. While parallel communications were popular for technologies in the 1990s, improved signalling methods mean that modern bus technologies use serial communications. This means transferring 1 bit at a time but working at a higher frequency.

The supported frequency (or speed), measured in hertz (cycles per second) or, more commonly, megahertz (MHz) or gigahertz (GHz), is another important characteristic of signalling.

The last thing to note is that signalling can either be digital or analogue. Computers use digital signalling, where pulses in the electrical signal refer to discrete binary values (ones and zeros). Analogue is a continuous, variable signal, just like natural sound waves. For some types of communication, a computer needs to translate between digital and analogue signals (for example, for video or audio signalling on analogue equipment) by sampling the analogue signal.



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Electrical Circuits

The last bit of preparatory information you need to master is the fundamental principles of electrical circuits and components. Electricity is the flow of electrons through a conductor. The characteristics of the electricity supply are measured as voltage, current (amperage), resistance, and power.

Voltage - the potential difference between two points (often likened to pressure in a water pipe) measured in Volts (V).

Current - the actual flow of electrons, measured in Amps (I). A current flows in a circuit, which is made when conductors form a continuous path between the positive and negative terminals of a power source. The size of the current is determined by the conductivity of the circuit (for example, a higher current can flow in a thicker wire than can in a thinner one).

Resistance - the conductivity of the media, measured in Ohms (Ω or R).

Power - the rate at which electricity is drawn from the supply by the device using it, measured in Watts. Power is equal to the Voltage multiplied by the Current (W=V*I).

Energy - the amount of power consumed by a device over time. This is measured in Watt-hours (or more typically Kilowatt-hours [kWh]).

In a Direct Current (DC) circuit, the charge flows in one direction from the positive to negative terminals of the power source at a constant voltage. DC is used for electronic circuits, which require stable voltages. Mains electricity is supplied as Alternating Current (AC), which means that the current flows in both directions around the circuit and the voltage alternates between low and high values. In the UK, mains power is supplied at 220-240V. In the US, mains power is 110-120V. AC is a cheap way to distribute electrical power over long distances but is incompatible with PC electronics. Transformers in the PC's power supply are used to convert AC to DC voltages.

Several other electrical components are used in a PC's electronic circuits:

Conductor - a material that is good at conducting electricity, such as gold, copper, or tin. These are used for wires and contacts.

Insulator - a material that does not conduct electricity, such as rubber or plastic. These are used as sheaths for wires, to prevent short circuits or electric shocks.




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Some materials are better conductors or insulators than others. Most materials have some degree of resistance, which creates heat as a current passes through it.

Semiconductor - a material that can act as both a conductor and an insulator. This provides switch-like functionality, where a circuit can be opened and closed, used to represent binary (on/off) digits.

Resistor - these oppose the flow of current without blocking it completely and are used to manage electronic circuits.

Diode - a valve, allowing current to flow in one direction only. These are used in a computer's power supply and as protection for components.

Fuse - this is a safety device. The flow of electricity creates heat. A fuse is designed so that if the current is too high, the heat will cause the fuse wire to melt and break, breaking the circuit and shutting off the current.

Transistor - in computers, these are semiconductor switches used to create logic devices. Typically a type called a Field Effect Transistor (FET) is used to make components such as CPUs and memory.

Capacitor - this stores electrical energy and is often used to regulate voltages. Note that a capacitor can hold charge after the power is removed.



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Review Questions / Module 1 / Unit 1 / Types of Computer

Answer the following questions. The correct answers are in the accompanying "Labs and References" manual.

1) Categorise each of the following as either input, output or storage:

Hard disk Storage

Keyboard Input

Printer Output

Speakers Output

Mouse Input

DVD Storage

2) At the rear of a system case are slots for adapter card ports. Why should these be covered with blanking plates if not in use? So that cooling is not affected.

3) What type of laptop would you look for if long battery life and weight were the top buying criteria? Ultra portable.

4) What is the most significant feature of a tablet PC? Handwriting recognition, enabled via a large touchscreen.

5) How many bytes are there in 1 GB system memory? 1,073,741,824 bytes (1024 x 1024 x 1024).

6) If some marketing literature talks about something working at 1 Gbps, what does this mean? Gbps is a transfer rate so it means that the nominal transfer rate is 1 Gbps - the actual throughput is likely to be lower once you take signalling and error correction into account.

7) How would you calculate the power used by a component? Multiply its voltage by the current it draws (W=V*I).

8) What causes a fuse to blow - excessive voltage or excessive current? Excess current.




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Module 1 / Unit 2 Motherboards

Objectives

On completion of this unit, you will be able to:

Identify and describe the main components of a motherboard:

CPU socket and chipset

System clock

Memory slots

I/O ports

ROM BIOS

Disk connectors

Identify expansion bus slots and cards.

Describe the capabilities of PCI, AGP, and PCIe bus standards.

Distinguish ATX, NLX, BTX, and proprietary motherboard form factors.

Identify the use and connectors for a PC Power Supply Unit (PSU) and laptop AC adapters and batteries.

Identify the components used for cooling (heat sinks and fans and liquid cooling systems).

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Study Notes Motherboards

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Motherboard Layout

A printed circuit board (variously called the motherboard, system board, or main board) houses the processor, memory and expansion slots. The type of motherboard influences system speed and upgrade capabilities.

There are a great many motherboard manufacturers, including Abit, AOpen (Acer), ASUSTek, Chaintech, Gigabyte, Intel, MSI, Shuttle, Tyan, and Via.

A typical motherboard consists of the following components:

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# Component # Component

1 ISA expansion slots (2) 10 SATA hard disk connectors (4)

2 PCI expansion slots (3) 11 PATA hard disk connector

3 PCI Express expansion slots (x1 and x16)

12 Floppy disk connector

4 Audio ports (speaker and microphone)

13 ATX power connector

5 Parallel and serial I/O ports 14 DIMM system memory slots

6 USB ports 15 CPU (LGA Socket)

7 PS/2 mouse and keyboard ports

16 CPU voltage regulators

8 ROM BIOS chip 17 Chipset

9 CMOS battery 18 Chipset (under heatsink)

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Bus Architecture

PCs are composed of many internal components, which communicate with each other using a bus. Physically, a bus is implemented on 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 are located in memory (address). The bus also carries power to a component and the timing signals that synchronise components.

"Bus architecture" usually means an expansion bus, used to connect peripheral devices. However, a variety of buses exist within a PC. Also, the way that bus designs are implemented has changed considerably as PC technology has developed and improved.

Internal and External Buses

One way of categorising types of bus is to divide them into internal and external. An internal (or local) bus connects core components, such as the CPU, memory, and the system controllers.

An external bus, or expansion bus, allows additional components to be connected to the computer. These components could be peripheral devices (located outside the case) or adapter cards (located inside the case).

"External" bus technologies do not necessarily extend outside the computer case. For example, PCI, the most popular expansion bus standard, provides connections to internal adapter cards only. A genuinely external bus (like 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, AMD's HyperTransport).

System Clock

The system clock synchronises the operation of all parts of the PC 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.

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Front Side Bus and Back Side Bus

You will often see the term Front Side Bus used in conjunction with the speed of a motherboard or chipset. It is also called the system bus, memory bus, or processor bus. It connects the processor to system memory via a memory controller. It runs at the same clock speed as system memory.

You may also see the term Back Side Bus or cache bus. This bus connects the CPU to external (Level 2) cache and runs at the same clock speed as the processor.

Parallel and Serial Bus Types

Historically, most bus designs have used parallel technology. The width of a parallel bus (32-bit or 64-bit for instance) and the clock speed determine bandwidth (or transfer rates).

Recent bus designs, notably USB, Firewire, and PCI Express, use serial communications. The data rate for serial communications is based on the clock speed and encoding mechanism.

Motherboard Components

All motherboards have connectors for the same sort of components: CPU, memory, disk drives, peripherals, and so on. However, the type and number of these connectors depends upon the models supported.

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 the memory sockets, and then covered by a heatsink and fan.

See Unit 1.3 for more information about CPUs and sockets.

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

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Type of processor, processor speed, and multiprocessing support.

Type and amount of system memory supported.

Type of power management supported.

Type(s) of system bus supported. Part of a chipset

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

System memory controller.

A keyboard and PS/2 mouse controller.

An 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), and SCSI interfaces.

Cache Memory

A computer stores the data for the programs and files currently open in system memory. The CPU has small registers to store instructions and data that it is processing. Instructions are moved in and out of these registers to the system memory.

Cache is a small block of high-speed memory that enhances performance by pre-loading (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 is using regularly.

Cache is designed in multiple levels. Level 1 cache is "closest" to the CPU and supports the fastest access. Level 2 cache is typically larger and a bit slower while Level 3 cache, if used, is larger and possibly a bit slower still1.

In early CPU designs, cache was implemented as a separate chip on the motherboard, but almost all new CPUs incorporate all types of cache as features on the CPU itself (on die).

1 You should note that the amount of cache is not always an effective means of comparing different systems. The "layout" of cache is dictated by the processor design. A given processor model might have a smaller amount of L2 cache than another given model and yet still work faster.



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Memory

PC memory can be categorised as RAM or ROM, each of which perform different functions within the PC. A motherboard will generally have between 2 and 4 slots for installation of system RAM. It also houses a ROM BIOS chip.

System RAM

Random Access Memory (RAM) is the working memory of the 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 when power is removed.

System RAM is normally DIMM memory modules fitted to motherboard sockets. The type of sockets and chipset determine what types of system memory can be installed. The capabilities of the memory controller and number of physical sockets determines how much memory can be fitted.

HP DIMM memory module

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

Memory is covered in detail in Unit 1.4 while solid state flash memory drives are covered in Unit 1.5.

ROM BIOS

The BIOS (Basic Input / Output System) is a ROM (Read Only Memory) chip that provides:

The industry standard program code that operates the fundamental components of the PC (for example, video, keyboard, printer port) and ensures that the design of each manufacturer's motherboard is PC-compatible.

The routines that allow the setup configuration of a PC (stored in CMOS RAM) to be viewed and edited.

The Power-on Self-Test (POST) diagnostic tests for the PC.

A Real Time Clock (RTC) that keeps track of the current date and time.

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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 it (software).

The ROM BIOS can be identified by a label on the chip showing the name of the manufacturer and a version number.

ROM BIOS chip

CMOS RAM

CMOS RAM stores the PC's basic configuration (for example, disk types, amount of memory installed, current time and date). This prevents the need for reconfiguration when powering on a PC.

CMOS stands for Complementary Metal-Oxide Semiconductor, which describes the manufacturing process used to make the RAM chip. CMOS devices require very little power to operate and use a small battery to maintain their settings. The CMOS battery is a coin cell lithium battery.

Lithium coin cell CMOS battery

I/O Ports

One of the functions of the motherboard is to provide the standard ports used to attach peripheral devices and cabling to the computer.

Motherboards provide a number of different I/O ports, typically including a serial port, parallel port, two or more USB ports, PS/2 keyboard and mouse ports, and network port.

Motherboard I/O ports 1) PS/2 mouse; 2) PS/2 keyboard; 3) Parallel port; 4) Serial port;

5) USB ports; 6) RJ-45 network port; 7) Audio ports [audio in, audio out, and microphone in]

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The functions and features of these ports are covered in detail in Unit 1.6.

Storage Device Ports

These are used for connecting internal storage devices such as hard disks, floppy disks, and CD drives.

There are various formats, including PATA, SATA, and SCSI.

Some motherboards contain built-in support for RAID (Redundant Array of Independent Disks). This is a means of increasing the performance and/or reliability of the disk system. Essentially, multiple physical disks are grouped together and treated as one disk.

See Unit 1.5 for more information about adding storage devices and configuring RAID.

Expansion Bus and Adapter Cards

Computers can support more than one expansion bus. Modern PCs use a multi-bus design, to support older technologies and allow for upgrades. For example, a PC might support PCI and PCI Express for adding internal adapter cards plus USB to allow the connection of peripherals.

Adapter Cards

An adapter (or interface) card is a circuit board that fits into an expansion slot. Typical examples are:

A sound card for connecting speakers, microphone, and other sound recording equipment.

A SCSI host adapter card for connecting additional storage devices such as CD or hard drives. SCSI cards can also connect external devices such as scanners and printers.

An I/O card providing additional ports, such as USB, Firewire, parallel, serial, or wireless (Infrared or Bluetooth for instance).

A modem card for providing dial-up access to a network or connection to an Internet Service Provider (ISP).




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A Network Interface Card (NIC) or Wi-Fi Adapter Card for connecting the PC to a Local Area Network (LAN) or Wireless LAN (WLAN).

HP Broadcom network adapter card (PCI)

Expansion Bus Technologies

Microprocessors, memory, and hard drives have all increased greatly in speed since the first versions were introduced to the marketplace. Buses are no exception to this; since the first 8-bit IBM design, several bus standards from different manufacturers have appeared and been replaced.

Legacy Bus Standards

The original IBM PCs (PC XT followed by PC AT) developed in 1983 used an 8-bit parallel bus called Industry Standard Architecture (ISA). This was updated in 1984 to a 16-bit bus.

In 1993, the Plug-and-Play standard was introduced. Plug-and-Play can dynamically assign resources (IRQs, DMA, and port addresses) to add-in cards that previously had to be configured manually, a process that was prone to creating resource conflicts that would make systems unstable.



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You may come across systems with legacy ISA slots (they are usually coloured black and distinctively larger than any other type of expansion slot) but non-Plug-and-Play motherboards and devices are extremely uncommon.

In the late 1980s, various 32-bit bus standards, including EISA (an update of ISA), MCA, and VESA Local Bus, were developed, but did not gain a large market footprint. The next major standard however is still in use today.

PCI Bus

The Peripheral Component Interconnect (PCI) bus was introduced in 1994 with the Pentium processor. It is still an important technology in terms of adapter card provision, though it is being superseded by PCI Express.

Several versions of PCI have been released subsequently to the first commercial version (2.0). Information about PCI standards is published at www.pcisig.org. The different capabilities are summarised below.

Bus Width and Clock Speed

PCI supports up to 5 devices (though each device can have up to 8 different functions) and allocates system resources using Plug-and-Play. Bandwidth on the PCI bus is shared between all devices. PCI supports bus mastering, meaning that the device can control the bus to transfer data to and from memory, without requiring the CPU.

The PCI architecture supports 32- and (with version 2.1) 64-bit parallel transfers of data. While the ISA bus could transfer 16-bits at a speed of 8 MHz, a PCI 2.1 bus transfers 32 or 64-bits of data at a clock speed of 33 MHz or 66 MHz. 32-bit at 33 MHz clock speed equates to transfer rates of up to 133 MBps; 64-bit at 66 MHz equates to up to 532 MBps.

The speed is synchronised with the system bus speed using a divisor. For example, a system bus running at 133 MHz would have a PCI bus running at half-speed (66 MHz).




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Adapter Card and Slot Form Factors

Originally, PCI cards were designed for 5V signalling, but the PCI 2.1 specification also allows for 3.3V and dual-voltage cards. In order to prevent the wrong type of PCI card from being inserted (for example, a 3.3V card in a 5V PCI slot), the keying for the three types of card is different.

5V pin position (50-51)

3.3V pin position (12-13)

Extra pins on 64-bit card

PCI adapter form factors

On a 5V card and slot, the key is at pins 50-51; on a 3.3V adapter, the key is at pins 12-13. A dual voltage (universal) adapter has both keys. 64-bit compatible slots and adapters have an extra 60 pins, making the slots distinctively longer2.

PCI 2.3 deprecates the use of 5V cards and most cards are universal. The vast majority of cards and slots for desktop systems are 32-bit. 64-bit PCI is more a feature of server-level systems.

Regardless of the voltage used for signalling, PCI slots can deliver up to 25W of power to an adapter.

PCI Interrupts

Interrupts allow a component to signal to the CPU that it has some data to transfer. The IBM PC design specifies 16 interrupts, most of which are required by system functions but some of which can be allocated to ISA expansion slots.

The PCI bus uses its own internal interrupt system for dealing with requests from the cards on a PCI bus. These interrupts are called #A through #D or #1 through #4. These do not require configuration as they are handled by the PCI BIOS. The PCI BIOS is also capable of assigning two or more PCI devices the same IRQ (PCI steering) without causing resource conflicts.

2 32-bit cards can be inserted into 64-bit slots (so long as it is not a 5V card).



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PCI-X

PCI-X is an update of PCI, used mainly in server systems. There are 32- and 64-bit versions with clock speeds of 66, 133, 266, and 533 MHz. It is backwards-compatible with PCI (using the same connectors) but only works with 3.3V (or universal) cards. 5V cards are not supported.

Riser Slots

CNR slot

Intel's Audio/Modem Riser (AMR) slots were designed to overcome the expense and difficulty of supporting sound and modem functions directly on the motherboard or using a PCI slot. The updated specification (Communications Network Riser [CNR]) adds support for a network adapter, Plug-and-Play, and USB. A rival interface (Advanced Communication Riser (ACR)) also adds support for wireless connections and is backwards-compatible with AMR.

Support for the slots is patchy compared to PCI and they are generally only used by computer manufacturers (OEMs) with most motherboard manufacturers preferring to integrate these components in the chipset.

AGP

The fact that the bandwidth of PCI is shared meant that it soon became a performance bottleneck when PCs started to be used for multimedia applications and games demanding 3D graphics. The Accelerated Graphics Port (AGP) was released in 1997 to circumvent PCI by providing direct links between the CPU, system memory, and graphics adapter.

AGP graphics card and motherboard showing 1) AGP 1.5V connector; 2) PCI (32-bit,

5V) connectors

1

2




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Several AGP standards have been introduced over the years:

Standard Type Effective Speed3

Max Transfer Rate

Voltage

AGP 1.0 AGP 1x

AGP 2x

32-bit @ 66 MHz

32-bit @ 133 MHz

266 MBps

533 MBps

3.3V signalling

AGP 2.04 AGP 4x

32-bit @ 266 MHz

1066 MBps 1.5V signalling

AGP 3.0 AGP 8x

32-bit @ 533 MHz

2133 MBps 0.8V signalling

Unless both card and connector support universal signalling, the card's signalling must be matched to the slot (1.5V and 0.8V are interchangeable though). Cards and connectors are keyed to prevent incorrect insertion.



Key positions for AGP; universal cards have both keys but universal connectors have neither key

The use of keys on cards and connectors is not always reliable for AGP (some cards and motherboards were incorrectly manufactured). Check the documentation for the card and motherboard carefully.

The AGP connector is typically colour-coded brown or maroon.

3 AGP speeds are synchronised to the PCI bus speed (66 MHz) but "pumped" or "strobed" meaning that data is transferred more than once on each clock cycle. The clock speeds quoted in the table are therefore effective speeds. Standards documentation has started to use the units Megatransfers per second (MT/s) in place of MHz to quote these speeds but you will not see this terminology in the A+ exams. 4 AGP Pro is an adaptation of AGP 4x for high-end CAD (Computer Aided Design) cards that require more power. Pro50 and Pro110 deliver up to 50 and 110 watts of power respectively (compared to the usual 25W). AGP Pro slots are larger than normal and require extra space on either side for cooling. Ordinary AGP cards can be fitted in Pro slots (subject to the signaling restrictions listed above) but Pro cards do not fit in standard slots.



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PCI Express (PCIe)

As CPU and memory bus speeds increased over the years, PCI represented a substantial bottleneck to computer performance. PCI and AGP are both parallel interfaces. Parallel interface speeds are limited by the problem of timing each signal (data skew). They are also more complex and costly to implement. Another performance barrier is the fact that the bandwidth of the PCI bus is shared between all the components connected to it and only one component can make use of the bus at any one time. This is a particular problem for video, disk access, and networking.

Various fixes were implemented to remove critical bottlenecks (such as using AGP for graphics or providing dedicated southbridge links for drive controllers or networking). These fixes added to the complexity of chip design and over time the PCI bus simply became inadequate.

PCI Express (PCIe) was released by Intel in 2004 as the replacement for the PCI/AGP architecture. PCIe uses point-to-point serial communications, meaning that each component can have a dedicated link to any other component. Connections are made via a switch, which routes data between components and can provide Quality of Service (QoS) to any component that needs it (for example, to prioritise real-time video over non-time critical data).

Each point-to-point connection is referred to as a link. The link sends both data and control / timing instructions. A link can make use of one or more lanes. Each lane consists of two wire pairs (four wires in total) using low voltage differential signalling. One pair is used to transmit and the other to receive (bi-directional).

Motherboard with 1) x1 PCIe connector; 2) x16 PCIe connector

A given component can support a specific number of lanes (x1, x2, x4, x8, x16, or x32) and the switch negotiates the maximum possible number of lanes to use (for example, x8 and x16 devices would use 8 lanes).

1 2




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Each lane supports a transfer rate of 250 MBps in each direction. A x32 link therefore supports up to 8 GBps in each direction. A x8 link is roughly equivalent to AGP 8x. Most graphics cards use x16 links (4 GBps in each direction).

A card will fit in any connector with an equal or greater number of lanes. For example, a x8 card will fit in a x8 or x16 socket, but not in a x1 or x4 socket.

As well as providing an expansion bus, PCIe is used for local bus connections under Intel architectures5. PCIe is software-compatible with PCI, meaning that PCI connectors can be included on a motherboard (to support legacy adapter cards) but PCI cards cannot be fitted into PCIe sockets.

PCIe can supply up to 75W to a device via the motherboard slot. An extra 75W power can be supplied via a 6-pin PCIe power connector (150W-ATX 1.0 Specification6). PCIe also features power management functions and support for hot swappable and hot pluggable adapters7.

HP PCIe DVI (x16 slot) and LAN (x1 slot) cards

PCI Express 2.0 compatible motherboards and adapters support transfer rates of 500 MBps per lane. Version 2.0 motherboards and adapters are interchangeable with earlier version 1.1 devices, though the added performance benefits are only realised if both components support 2.0. Version 2.0 allows for slots with a smaller footprint than previously (a 2.0 x8 slot delivers the same performance as a 1.1 x16 slot).

PCIe 2.0 also specifies a power draw from the slot of up to 150W and an 8-pin auxiliary power connector delivering another 150W.

5 AMD-based systems use the rival Direct Connect architecture with HyperTransport links between components. However, AMD chipsets also support PCIe connectors for graphics and other expansion cards. 6 Some top-end graphics cards requiring more than 150W use two extra connectors. 7 A hot pluggable card can be added when the system is active but cannot be removed until the system is shut down. A hot swappable card can be added or removed while the system is powered up. Note that not many desktop cards actually support hot plugging or hot swapping. This technology is usually a feature of devices designed for servers.



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Motherboard Form Factors

The form factor of the motherboard describes its shape, physical layout, and the type of case and power supply that can be used. Two motherboards may have exactly the same functionality but different form factors; the difference is the layout of the components on the motherboard. Most motherboards are based on the ATX or Micro ATX design. You can obtain more information about motherboard form factors at www.formfactors.org.

ATX and Micro ATX

1

2

3

5

8 7

6

9

4

11

12

10


1 ISA expansion slots (2) 7 Floppy disk connector

2 PCI expansion slots (3) 8 DIMM system memory slots (2)

3 PCI Express expansion slot (x1)

9 ATX power connector

4 PCI Express expansion slot (x16)

10 CPU (LGA Socket)

5 SATA hard disk connectors (4)

11 Voltage regulators

6 PATA hard disk connector 12 External I/O ports

ATX motherboard layout




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The ATX (Advanced Technology Extended) specification was developed by Intel in 1995 to provide a new design for PC motherboards, updating the previous AT form factor.

Full size ATX boards are 12" wide by 9.6" deep. The Micro ATX standard specifies a 9.6" square board, with fewer expansion slots (four compared to seven). There is also a Mini-ATX size of 11.2" by 8.2" and a Flex-ATX standard for even smaller boards (9" by 7.5").

Most micro ATX boards can be mounted in ATX cases.

NLX and Riser Cards

Some PC case designs are slimline, meaning that there is not enough space for full height expansion cards. This problem is addressed by providing a riser card (or daughter board) at right-angles to the main board. Historically, the LPX and NLX form factors were designed as riser architectures.

NLX motherboard

Most manufacturers just use the ATX riser card specification (which specifies a 2x11 connector plus a PCI connector for the riser card), a spare PCI connector, or low profile adapter cards. A low profile card is about half the height of a standard card and so fits within a slimline case.

Riser card providing full height PCIe slot for HP Compaq Ultraslim Desktop



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BTX

The BTX (Balanced Technology Extended) form factor was developed by Intel in 2003. It is designed to be scalable to allow for system designs of different heights and widths, provide better cooling of hot running CPUs, system memory, and graphics cards (using in-line airflow), and reduce noise.

1

2

3

5

8

7

6

9

4

10


1 DIMM system memory slots (4)

6 SATA hard disk connectors (4)

2 External I/O ports 7 ATX power connector

3 Voltage regulators 8 PCI Express expansion slot (x16)

4 CPU (LGA Socket) 9 PCI Express expansion slot (x1)

5 PATA hard disk connector 10 PCI expansion slots (2)

BTX motherboard layout

The standard has yet to catch on with motherboard manufacturers, though some OEMs have adopted it. All boards are 266.70 mm (10.5") deep but there are pico, nano, micro, and standard widths.

BTX also specifies full height cases for use with normal expansion cards (Type I) and slimline cases (Type II) supporting riser or low profile cards.




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Other Form Factors

Small Form Factor (SFF) PCs are becoming popular as home machines (and in image-conscious offices). Leading products include Shuttle's range of XPCs and Via's mini-ITX form factor.

The latest models support standard PCI, AGP, or PCIe cards (though there are generally just one or two slots) and generally have one 5" and one 3.5" drive bay.

Summary

The following table summarises some of the main form factors still in general use:

Standard WidthxHeight Description

ATX 12x9.6"

305x244 mm

Full size layout with up to seven expansion slots.

MicroATX 9.6x9.6"

305x244 mm

SFF layout with up to four expansion slots (though can typically be fitted to a standard ATX case).

FlexATX 9x7.5"

229x191 mm

Intel developed addendum to MicroATX.

BTX 12.8x10.5"

325x267 mm

Full size layout with up to seven expansion slots.

MicroBTX 10.4x10.5"

264x267 mm

Supports up to four expansion slots.

NanoBTX 8.8x10.5"

224x267 mm

Up to two expansion slots.

PicoBTX 8x10.5"

203x267 mm

Supports just one expansion slot.

Mini-ITX 6.7x6.7"

170x170 mm

SFF design created by VIA Technologies, supporting one expansion slot. There are also even smaller Nano- and Pico- versions with no support for expansion cards.

Standoffs

It is important that the motherboard does not touch the system case or its components might short circuit. The motherboard is attached to the case by standoffs, which hold it slightly above the level of the case. The number and position of the standoffs is fixed by the form factor. The standoffs may be brass or plastic lugs or may be built into the case.



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Laptop Motherboards

While there are a few "barebones" laptop vendors, most laptops are proprietary systems produced by (notably) HP, Dell, Lenovo, Sony, Toshiba, and ASUS. The chassis and motherboard are not designed in such a way as to allow the simple upgrade and replacement of components, as PCs are. The designs emphasise size, weight, and thermal efficiency over upgrade potential.

A laptop's chipset is likely to contain more integrated features than a desktop's, including wireless networking (Wi-Fi) and connectivity and a modem. Components that would be replaceable in a desktop system, such as CPU, graphics card, and sound card, are often soldered to the motherboard or provided as part of the chipset.

Power Supply Unit (PSU)

The Power Supply Unit (PSU) delivers DC (Direct Current) low voltage power to the PC components. Mains electricity is supplied as Alternating Current (AC) at high voltage (110V or 220-240V, depending on which country you are in) because it is a cheap, efficient way of transmitting electricity over long distances. Computer components require low, stable voltage to work properly.

PSU Components

The PSU contains transformers (to step down to lower voltages), rectifiers (to convert AC to DC), and filters and regulators (to ensure a "clean" output or steady voltage). The other important component in the PSU is the fan, which dissipates the heat generated. Better quality models feature low noise fans.

The PSU is not user-serviceable - do not attempt to open the casing without the proper tools, knowledge, and experience. The PSU contains capacitors, which can store lethal electrical charges for long after the unit is disconnected from the power supply.

A PSU is plugged into an electrical outlet using a suitable power cable. The plug should suit the outlet type of the country you are in, though "travel plug" converters are commonly available. Some PSUs also have an outlet to plug a monitor power cable into. The plug should always be fitted with a working fuse of the correct rating (typically 3A or 5A).

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A critical point to recognise if you are taking a computer to a different country is to ensure that the PSU is set to the correct input voltage. Some PSUs can accept different input voltages and are auto-switching (or auto-sensing); some have a switch to select the correct voltage; others can only accept one type of input voltage (fixed). The input operating voltages should be clearly marked on the unit and accompanying documentation.

Autoswitching PSU (left) and PSU with manual voltage selector (between the power

points)

Power Rating

A PSU must be able to supply adequate power to all the PC's components. The maximum power output (power rating) available from a PC power supply is measured in watts (calculated as voltage multiplied by current [V*I]).

The unit found in a standard desktop PC is typically rated at around 200-300W. This is normally sufficient for a full range of expansion cards and around five peripherals (floppy disks, hard disk units, and CD-ROM drives). Slimline desktop PCs are generally fitted with 100-200W power supplies. Tower systems and servers often have units rated over 300W - enough to power a full complement of disk drives, tape units, and other storage devices. Gaming PCs also require 500W or better power supplies to cope with the high specification CPU and graphics card(s).

The power requirement of different components varies widely (for example, CPUs can range from 17W to over 100W, depending on the model). If you are building or upgrading a system, the simplest way to work out the power requirement is to use an online calculator. Examples of these tools include outervision.com and journeysystems.com.



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When specifying a PSU for a system that needs a lot of power, it is also important to look closely at the power distribution of each unit. Power distribution refers to how much power is supplied over each rail. A rail is a wire providing current at a particular voltage. For example, the following chart shows the maximum output for a PSU rated at 450W:

Output Rail Max Load Max Output

+3.3V 20A 130W8

+5V 20A

+12V 33A 396W

-12V 0.8A 9.6W

+5V (Standby) 2.5A 12.5W

For a modern computer, the output rating of the +12V rail (or rails) is the most important factor, as 12V is the most heavily used. Also note that peak output is only achieved under optimum conditions; sustained (or continuous) power output represents "real world" performance.

The power output is not the same as the power the PSU draws from the supply. PSUs typically work at around 75% efficiency, meaning a 300W supply draws 400W from the outlet. The extra energy is lost mainly as heat.

As power becomes more expensive, power efficiency is an increasingly important criterion to use when selecting a PSU. From 2007, an ENERGY STAR compliant PSU must be 80% efficient at 20-100% of load (many vendors only display the efficiency obtained under low load). 80 PLUS is a similar rating scheme.

Form Factor and Voltage Outputs

Most PSUs are based on the ATX form factor, which can also be used with full-size BTX motherboards. The form factor determines both the size of the unit and position of the fan (allowing it to be screwed into a standard case) and the standard pin-outs for the power connectors.

8 The output of +3.3V and +5V has a combined limit. Note that no combination of values actually adds up to 450W but PSU outputs are self-certified by the manufacturers so this situation is not uncommon.




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The connectors supply various combinations of 3.3V, 5V, and 12V positive and negative current. Not all components use power at precisely these voltages. Voltage regulators on the motherboard are used to correct the voltage supplied from the PSU to the voltage required by the component.

The ATX PSU standard has gone through a number of revisions. The standard ATX PSU has:

One 20-pin P1 connector for the motherboard.

A number of 4-pin Molex connectors for peripheral devices

A 4-pin mini-Molex (or Berg) connector for the floppy drive.

20-pin P1 motherboard, 4-pin Molex, 4-pin floppy (Berg), and 15-pin SATA power

connectors

In 2000, Intel produced an updated ATX12V specification with an additional +12V connector to support the Pentium 4 CPU9. This is provided as an extra, square 4-pin connector (P4)10. An update to this specification defined optional support for SATA power connectors (to power hard disk drives)11. In 2003, the ATX12V specification was updated to version 2, which defined a 24-pin P1 connector to replace the 20-pin one. Power distribution was changed to favour the 12V circuits. It also made the provision of SATA connectors compulsory. The ATX12V 2.2 specification adds a 6-pin connector to supply extra power to PCIe graphics cards12.

Modular PSUs have cables that are detachable from the PSU unit, allowing only the connectors actually required to be used. This reduces clutter within the chassis, improving air flow and cooling.

The general compatibility of different ATX PSU specifications to systems based on different CPUs is as follows:

9 This is often misleadingly referred to as Dual 12V Output, which implies separately generated outputs (giving better stability). In fact, most PSUs only generate one 12V output and split it between two or four rails, to comply with electrical safety standards (overcurrent protection). 10 ATX12V v1 power supplies rated over 250W may also feature a 6-pin Aux connector. 11 If a PSU has no SATA connectors, Molex-to-SATA converters are available. 12 PSUs designed for dual card systems will feature two PCIe connectors. PSUs supporting the PCIe 2.0 specification have 8-pin connectors delivering 150W.



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PSU Type CPU

Legacy (pre-P4 / Athlon)

P4 / Athlon Core / Athlon 64

ATX Good Incompatible Incompatible

ATX12V v1 OK Good Incompatible

ATX12V v2 Poor / Incompatible

Good Good

Some vendors may use proprietary designs, which can sometimes closely resemble a "standard" ATX PSU, but may use different pin-outs for the power connectors. An example of this is some of the systems produced by Dell. When upgrading or replacing a power supply, it is critical to check the documentation accompanying the system carefully.

Another use of non-ATX PSUs is in SFF (Small Form Factor) PCs. There are a number of SFF PSU specifications from Intel (CFX, SFX, LFX, and TFX) but such systems are equally likely to use proprietary designs (such as Shuttle or AOpen). You can check www.formfactors.org for complete descriptions of the Intel specifications.

Power Supplies for Portable Computers

Portable computers offer both mains power and battery operation.

Mains Power

To operate from mains power, the laptop needs a power supply that can convert from the AC (Alternating Current) supplied by the power company to the DC (Direct Current) voltages used by the laptop's components. The power supply is provided as an external AC adapter.

Mains AC adapters are normally universal (or auto-switching) and can operate from any 110-240V 50/60Hz supply (check the label to confirm). Some adapters (notably some sold with US machines) are fixed-input (for instance, they only work with a 110V supply or have to be manually switched to the correct input).

AC adapter

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AC adapter input and output information

When using a laptop abroad, in addition to a universal AC adapter, you will also need a power plug adapter to fit the type of socket used in that country. It is also best to get a surge protector designed for the voltage used in the country too. This helps to protect the laptop from damage.

Plugging a fixed-input 240V adapter into a 110V supply won't cause any damage (though the laptop won't work), but plugging a fixed-input 110V adapter into a 240V supply will.

AC adapters are also rated for their power output (ranging from around 65 - 120W). Again, this information will be printed on the adapter label (as shown above). Output (W) is calculated by multiplying voltage (V) by current (I). Obviously, a larger output will be able to power more peripheral devices.

Note that the power output of adapters and batteries can vary, so using an adapter designed for an ultra-mobile model probably won't work with a desktop replacement, even if it's the same brand. A 90W adapter should be sufficient for most uses, but always check the documentation carefully.

Battery Power

Laptop computers use removable, rechargeable battery packs. Older technologies, such as Ni-Cad and NiMH, have been replaced by Lithium ion (Li-ion). Li-ion batteries have good storage capacity and slower loss of charge. The metals used in their manufacture are slightly less damaging to the environment. They are typically available in 6, 9, or 12 cell versions, with more cells providing for a longer charge.



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Cooling Systems

Heat is a by-product of pushing electric current through the various electronic components in the computer. The faster the components work, the more heat is produced. Excessive temperatures can cause the components to malfunction or even damage them. One of the most significant problems with CPUs (and graphics cards) is their thermal output. While Intel and AMD are both focussing on making new CPU designs more thermally-efficient, all CPUs require cooling. Also, a specific CPU model requires a specific cooling system as some run hotter than others (later Pentium 4s being a good example13).

Heatsinks and Thermal Compound

A heatsink is a block of metal with fins. As the fins expose a larger surface area to the air around the component, a greater cooling effect by convection is achieved. The heatsink is "glued" to the surface of the chip using a thermal pad (or compound on earlier models) to ensure the best transfer of heat.

In order to work well, a heatsink requires good airflow around the PC.

Fans

A fan improves air flow and so helps to dissipate heat. Fans are used for the power supply and chassis exhaust points.

Typically, the speed of the fan is varied according to the temperature and sensors are used to detect whether a fan has failed.

PSU (1) and chassis (2) fans on an HP Compaq PC

13 The ideal operating temperatures of CPUs vary quite widely (between 40°C and 90°C).

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Smaller fans may be used to improve the performance of the heatsink on CPU and GPUs.

Fan assembly on a CPU (left) and ATI Radeon graphics processor (right)

The main problem with fans, especially at the lower end of the market, is that they generate noise. A fan also needs to be matched to the CPU model to ensure that it is powerful enough to cope with the processor's thermal output.

Some chassis designs incorporate a plastic shroud to cover the CPU and channel the flow of air to the fan.

Plastic shroud (1) covering the CPU and channelling the air to the fan exhaust (2) on

an HP PC system

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Heat Pipes and Heat Spreaders

A heat pipe is a sealed tube containing some type of coolant (water or ethanol). The liquid close to the heat source evaporates then condenses at a cooler point in the pipe and flows back towards the heat source. The cool parts of the pipe are kept so by convection. This mechanism is more effective than a simple heatsink and fan assembly. It is necessary for a CPU that runs particularly hot or where there is not much space for airflow within the chassis. A dual heat pipe has two tubes, providing better cooling.

A heat spreader uses the same design but is a flat container rather than a pipe. This design is better suited to portable computers.

Liquid Cooling Systems

Liquid-cooled Alienware PC

PCs used for high-end gaming (those with twin graphics cards for instance) and with overclocked components may generate more heat than basic thermal management can cope with. PCs used where the ambient temperature is very high may also require exceptional cooling measures.

Liquid cooling refers to a system of pumping water around the chassis. Water is a much more effective coolant than air convection and a good pump can run more quietly than numerous fans. Liquid cooling makes maintenance and upgrades more difficult, requires quite a lot of power to run, and is costly.




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Review Questions / Module 1 / Unit 2 / Motherboards

Answer the following questions. The correct answers are in the accompanying "Labs and References" manual.

1) True or false? The Real Time Clock controls the timing of signals between the CPU and other components. False - the system clock controls timing; the Real Time Clock keeps track of the date and time.

2) What is the main function of the chipset? Provides controllers for the CPU to interface with other components (memory and expansion bus for instance).

3) What type of socket is used to install system memory? DIMM.

4) State whether the following are RAM or ROM:

BIOS ROM

CMOS RAM

Cache RAM

5) Give three examples of an adapter card: Graphics adapter, sound card, network interface card, SCSI card, modem card, multi-function I/O card.

6) How can you distinguish between 32-bit and 64-bit PCI cards? 64-bit cards have extra pins and so fit in a longer slot.

7) What is the maximum bandwidth available from AGP? 2133 MBps.

8) Is PCI Express a similar technology to PCI? No - PCI Express uses serial point-to-point transmissions rather than parallel transfers over a shared bus. Software compatibility with PCI means that motherboards can support both types of bus.

9) Apart from addressing and data transfer, what are the other functions of a bus? Carry power and timing signals to a component.

10) You have a x8 PCIe SCSI host adapter card - can you fit this in a x16 slot? Yes.



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11) What is the bandwidth of a PCIe x16 graphics adapter? 4 GBps.

12) True or false? Slimline case designs must use NLX motherboards. False - ATX and BTX can both be used with riser cards or low-profile adapter cards.

13) Some Small Form Factor PC motherboards are based on proprietary designs, but what ATX standard exists for SFF? Flex-ATX (9x7.5").

14) How many expansion slots does a NanoBTX board support? Two.

15) What is the significance of a PSU's power output? Determines the number of drives, expansion cards, and peripherals that the PC can support (assuming the peripherals do not have their own power supply).

16) Are you able to use a standard ATX PSU with a BTX motherboard? Yes (assuming it is a modern ATX12V supply).

17) You have a power supply with an 8-pin connector on it - what is this for? Supplies power to a PCI Express graphics card.

18) A modern CPU uses voltages of around 1.5V or less. How does the motherboard supply the correct voltage to the CPU if an ATX supply consists of 3.3V, 5V, and 12V outputs? Using a voltage regulator.

19) What type of AC adapter do you need for your laptop if foreign travel is part of your job? Auto-switching / universal.

20) What is the difference between a heatsink and a heat pipe? A heat pipe contains liquid to improve cooling by convection.