OReilly PC hardware in a nutshell 2nd edition jun 2002 ISBN 0596003536

Carefully researched and written, PC Hardware in a Nutshell, 2nd Edition is packed with useful and unbiasedinformation, including how-to advice for specific components, ample reference m

Carefully researched and written, PC Hardware in a Nutshell, 2nd Edition is packed with useful and unbiased

information, including how-to advice for specific components, ample reference material, and a comprehensive case study on building a PC To the point yet complete, this book provides an enormous amount of timeless information intended for anyone who buys, builds, upgrades, or repairs PCs in a corporate, small business, or home setting.

Chapter 9 Tape Drives

Section 9.1 Choosing a Tape Drive

Section 9.2 Installing and Configuring a Tape Drive Section 9.3 Care and Feeding of a Tape Drive

Section 9.4 Troubleshooting Tape Drive Problems Section 9.5 The Dirty Little Secret of Long Filenames Section 9.6 Developing a Backup Strategy

Section 28.8 Step 8: Install the Motherboard

Section 28.9 Step 9: Connect Cables to the Motherboard Section 28.10 Step 10: Install Expansion Cards

Section 28.11 Step 11: Perform the "Smoke Test" Section 28.12 Step 12: Install Software

Section 28.13 Step 13: Finishing Touches

Colophon

Index

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contained herein

To my agent, David L Rogelberg No author could hope for a better colleague.

Robert Bruce Thompson

To my parents, Richard Carl "Dutch" Fritchman and Sankie Callahan Fritchman, who gave me the opportunities and guidance to help me succeed.

Barbara Fritchman Thompson

My job is to persuade you to buy this book, or make you feel you've

made the right choice if you've already bought it

That's easy because there's not another book like this, and if you domuch with computers you need a good reference work on hardware Ofcourse there are massively larger books on the subject, but that's just thepoint: most of the time you're not looking for a long essay on the subject,you need information, and reliable judgment, both of which Robert BruceThompson is highlyI am tempted to say uniquelyqualified to give

I can say this with some authority I've never actually met Robert BruceThompson face to face, but we've been friends for several years Such isthe way with the modern Internet I first "met" him in the dark days afterBYTE Magazine was suddenly and unexpectedly folded, and I continued

my column on my web site (Shameless self-promotion:

www.jerrypournelle.com.) One of the features of both the web site andthe column was reader mail, and there soon appeared a corps of

regulars, all experts in one or another field, all articulate, and all verygenerous with their time and effort Robert Thompson stood out amongthese, and it was soon clear to me that he knew far more about computerhardware than I did That was surprising: I've been in this business since

1978, and while no one can know everything, I thought I knew a good bitabout nearly everything I do, too, but Thompson knows more, both indepth and breadth, and that's astonishing

He's pretty careful, too Over the years I have found I agree with most ofhis conclusions, and when we disagree I have to rethink my position,because he's been right at least as often as I have been

So You have here a well-written book by someone who understands thesubject It's about computer hardware and nearly everyone needs a goodopinionated reference work on that subject, provided the opinions aresound, which in Thompson's case they certainly are It's published byO'Reilly, which means it's well edited by editors who resist the temptation

Jerry Pournelle

Chaos Manor

April 2002

PC Hardware in a Nutshell An oxymoron, as it turns out When Robert

began work on the first edition of this book in late 1998, he planned towrite a 300-page book in five months Barbara joined the project early, atfirst as the researcher and later as the full co-author After more than 18months of working seven days a week, including last-minute rewrites tomake everything as current as possible, we finally completed the firstedition

Robert decided to write the first edition because he couldn't find a goodanswer to what seemed to be a simple question Robert, who has

extensive PC experience, wanted to buy his first CD burner but didn'tknow much about them He needed information about how to choose,install, configure, and use a CD burner It would have been easy to checkarticles about CD burners in hardware-oriented magazines and

enthusiast web sites, but Robert didn't trust them to provide accurate andunbiased information

He next checked the shelf of PC hardware books he owns What he

found in those books was lots of interesting information, but a surprising dearth of useful information For example, one very popular title devoted

fewer than five of its 1500+ pages to CD-R and CD-RW, and most ofthose few pages described the history and low-level functioning of thesedevices Advice on how to choose a CD burner? Advice on how to install

it, configure it, use it, or troubleshoot it? Next to none That same bookdevoted nearly 70 pages to a list of vendorsinformation easily accessible

on the Webso the shortage of information couldn't have been a result ofpage count constraints

We were determined to write a book filled with useful information Youwon't find tables of drive parameters for hundreds of obsolete disk drives,instructions on how to change the interleave by low-level formatting an

XT hard drive, charts of keyboard scan codes, and so on As interesting

as those things might be, they fail the useful test Pruning stuff that was

merely interesting was painful, because we like to read interesting stuff

most PC hardware books Interesting is quick and easy to write Useful is slow and hard, because you actually have to do all the stuff.

We found numerous errors repeated nearly verbatim in more than onebookthings that were clearly wrong, but that an author had simply

repeated without verifying it rather than taking the time to check for

himself We're guilty of that at times, too When we list the pinouts for agameport, for example, we get that information from published sources.But surprisingly often, we found that these sources disagreed, and sowere forced to check for ourselves

And, boy, did we expend an incredible amount of time and effort checkingthings for ourselves Rather than simply repeating what others have saidabout CD burners, for example, we decided to find out for ourselves.Doing that required building four computerstwo IDE and two SCSI, oneeach with Windows 98 and Windows NTand testing each configurationwith different drive models by burning numerous CDs with each Aboutten 14-hour days and 400 CD blanks later, we finally had a handle on CDburners All that work turned into just a few pages and some specificproduct recommendations But all that work was necessary if we wanted

to write something more than just a me-too book

Our efforts were rewarded The first edition of PC Hardware in a Nutshell

sold well, and was widely acclaimed by readers and reviewers alike Forexample, Barnes & Noble had this to say:

Here's one PC hardware book that pulls no punches It even

recommends specific brands and models, and tells you whyso youcan evaluate whatever's on sale when you're ready to buy The

authors speak to you as if you're planning to build your own

computer from scratch That's the "big kahuna" PC maintenance

project, so the book's easily up to any "smaller" challengeslike

adding a CD burner, or maybe replacing your motherboard And it'sall newnot padded with obsolete data and techniques Specific,

comprehensive, and relentlessly usefulsuperb!

detailed testing and comparisons of numerous products, the results ofwhich often boil down to a couple of paragraphs of advice or a singleproduct recommendation We greatly expanded both the breadth of

topics covered and the level of detail presented This edition is, in everyrespect, twice the book that the first edition was

We wouldn't have started this project unless we thought we could write

the best PC hardware book available We think this second edition of PC

Hardware in a Nutshell meets that goal, and we hope you will think so

too

This book is intended for anyone who buys, builds, upgrades, or repairsPCs in a corporate, small-business, or home setting If you want to buy a

PC, this book tells you what to look forand what to look out for If youwant to build a PC, this book explains, component by component, the keyparts of a PC, describes the important characteristics of each, providesbuying guidelines, recommends specific products (by brand name andmodel), and takes you step-by-step through building the PC If you have

an older PC, this book tells you what you need to know to upgrade itif itmakes sense to do soas well as when it makes more sense simply toretire it to less demanding duties Finally, if your PC breaks, this booktells you what you need to know to troubleshoot the problem and thenchoose and install replacement parts

This book focuses on PC hardware running Windows 95/98/98SE/Me,Windows 2000/XP, and Windows NT 4, which together power the vastmajority of PCs We would also have liked to cover Linux, but we don'tyet understand it well enough to write authoritatively about it That willchange One of Robert's goals during early 2002 is to migrate his primarydesktop system to Linux By year-end 2002, we will be running Linux onmany of our servers and desktops

Each chapter of this book is devoted to one topic, and is self-supporting.The first two chapters provide an overview of PC hardware and

standards, as well as detailed advice about buying, building, upgrading,and repairing PCs They describe the tools and software you'll need,explain basic procedures like installing expansion cards, and detail thetips and tricks we've learned during 20 years of working on PCs Thesechapters include:

Chapter 1

Chapter 2

The second group of chapters covers the core components of any

PCmotherboards, processors, and memory These chapters take theform used throughout the rest of the book, beginning with brief

background information about the component, followed by an explanation

of the important characteristics, guidelines on choosing among

competing products, instructions for installing and configuring the

component, troubleshooting information, if applicable, and a final "OurPicks" section, which tells you which products we recommend This

drives, which despite the arrival of new technologies remain the bestchoice for backing up data This group includes the following chapters:

Chapter 6

Chapter 23

Chapter 24

The ninth group of chapters covers three componentscases, PC powersupplies, and backup power suppliesthat receive little attention, but areimportant to system reliability and usability We detail the important

characteristics of each, and provide guidelines for choosing the best caseand power supplies for your system This group includes the followingchapters:

PC hardware changes in Internet time Products that were the hottestthings on the market (or even preproduction engineering samples) when

we started working with them had become mainstream when we went topress, and may even have been discontinued by the time the book

instead concentrate here on important characteristics and guidelines,which don't change nearly as fast

We recognize, though, that many people want specific advice by makeand model"Which motherboard/drive/monitor should I buy?" is one of themost common questions we getso we've gone to some trouble to createand update pages on our web site that provide detailed

recommendations We still provide general recommendations in the OurPicks sections, but you'll now find our specific recommendationsby brandname and modelon our web site, at:

http://www.hardwareguys.com/picks/picks.html

We base these recommendations on our own experience, not after usingthe product for a day or a week, but after extensive day-in-day-out useunder realistic conditions If we say we found a particular CD burner to bedurable, that means that we used that CD burner extensively and burned

a bunch of CDs with it If we say a particular motherboard is stable, thatmeans we used it in one or more of our own systems over a period ofweeks or months and found that it didn't crash even when performingstressful tasks like running a full benchmark suite or compiling a Linuxkernel If we say a particular monitor is the best we've used, it's because

we sat in front of it for many long hours while writing this book And soon

This book uses the following typographical conventions:

italic

is used for filenames, directories, hostnames, domain names, URLs,and to emphasize new terms when they are first introduced

[ option ]

When showing command syntax, we place optional parts of thecommand within brackets For example, ls [-l] means that the -l

option is not required

This is an example of a tip or note They suggest effective ways

to accomplish common tasks, highlight important advice, or convey supplemental information that may not be important to all readers.

This is an example of a warning Warnings highlight dangerous proceduresthose that may damage you, your hardware, or your data Disregard warnings at your own peril.

Please address comments and questions concerning this book to thepublisher:

http://www.oreilly.com/catalog/pchardnut2

To comment or ask technical questions about this book, send email to:

bookquestions@oreilly.com

For more information about books, conferences, Resource Centers, andthe O'Reilly Network, see the O'Reilly web site at:

We also have a web site for the book, which includes updated hardwarerecommendations, buying guides, and articles, as well as errata, archived

http://www.hardwareguys.com

We also maintain a message board for the book, where you can read andpost messages about PC hardware topics You can read messages as aguest, but if you want to post messages you must register as a member

of the message board We keep registration information confidential, andyou can choose to have your email address hidden on any messagesyou post

http://forums.hardwareguys.com/

We each maintain a personal journal page, updated daily, which

frequently includes references to new PC hardware we're working with,problems we've discovered, and other things we think are interesting.You can view these journal pages at:

Barbara: http://www.fritchman.com/diaries/thisweek.html

Robert: http://www.ttgnet.com/thisweek.html

In addition to the O'Reilly production staff, who are listed individually inthe Colophon, we want to thank our technical reviewers, Jon Barrett andFrancisco García Maceda These guys did yeoman duty in finding

mistakes we made and in making numerous useful suggestions, all ofwhich helped make this a better book

We also want to thank our contacts at the hardware companies, whoprovided technical help, evaluation units, and other assistance There arefar too many to list individually, but they know who they are We also want

to thank the readers of our web sites and message boards, many of

whom have taken the time to offer useful suggestions for improvements

to the book Thanks, folks We couldn't have done it without you

The photographs in this book were shot with Olympus digital cameras.We've used many digital cameras, and have developed a strong

preference for Olympus models Their experience as a premier maker offilm cameras shows clearly in the construction quality, image quality,

functionality, and ease-of-use of Olympus digital cameras

Finally, we want to thank our editor, Robert J Denn, and our publisher,Tim O'Reilly, both of whom contributed numerous useful comments andsuggestions

Thank you for buying the second edition of PC Hardware in a Nutshell.

We hope you enjoy reading it as much as we enjoyed writing it

This chapter covers a mixed bag of important fundamental informationabout PCs, including how PCs are defined, an overview of PC

components and technologies, a brief explanation of system resources,guidelines for building, buying, and upgrading PCs, smart buying

practices, and suggestions as to what to do with old PCs

These days, Intel and Microsoft jointly define the de facto PC standard In

fact, a good working definition of a PC is a computer that uses an Intel or

compatible processor and can run a Microsoft operating system Any computer that meets both requirementsa so-called Wintel computeris a

PC A computer that does not is not Computers based on some Intelprocessors cannot run any Microsoft operating system, and thus are notPCs Conversely, some computers with non-Intel processors can runMicrosoft operating systems, but also do not qualify as PCs For

example, DEC Alpha minicomputers running Windows NT 4 are not PCs

Two formal documents, described in the following sections, define thejoint Intel/Microsoft standards for systems and components you are likely

to be working with These standards are de facto in the sense that

system and peripheral makers are not required to comply with them to

manufacture and sell their products They might as well be de jure

standards, however, because compliance is required to achieve suchnearly mandatory certifications as inclusion on the Windows NT/2000/XPHardware Compatibility Lists

1.1.1 PC 99 System Design Guide

PC 99 System Design Guide (PC 99) is a book-length document that

defines required, recommended, and optional (neither required nor

example, in recommending Device Bay and 1394 as standard storageinterfaces In other ways it was far behind: for example, in requiring only

a 300 MHz processor and 32 MB of RAM for some configurations Someportions are skewed to Intel CPUs (e.g., an L2 cache requirement wascut from 512 KB to 256 KB when Intel shipped Coppermine Pentium IIICPUs with 256 KB L2 cacheprobably not a coincidence), while many

others are skewed toward Microsoft operating systems Neither of those

is surprising in the document that defines the Wintel standard All of thatsaid, PC 99 was and remains an important document because it definedthe direction of PC development as we entered the new millennium

You can purchase PC 99 in book form (Microsoft Press, 1998) You can

view or download PC991.0 in Acrobat format

(http://developer.intel.com/design/desguide/) or PC99athe final release ofPC99, with minor updates and correctionsin compiled HTML help format(http://www.microsoft.com/hwdev/platform/pcdesign/desguide/default.asp).The PC Design Guide home page (http://www.pcdesguide.org) also

Connector Color Connector Color

Analog VGA Blue PS/2-compatible keyboard Purple

Audio Line-in Light Blue PS/2-compatible mouse Green

Digital monitor/flat panel White Speaker out/subwoofer Orange

IEEE 1394 Grey Right-to-left speaker Brown

Parallel Burgundy SCSI, LAN, telephone, etc Not defined

1.1.2 PC 2001 System Design Guide

The PC 2001 System Design Guide (PC 2001) is, according to Intel and

Microsoft, the final document in this series In many respects, PC 2001 ismore an addendum to PC 99 than a self-supporting document Many PC

PC 2001 no longer categorizes components and functionality as

"recommended," instead specifying only those that are required Acomponent or function that is not required is not mentioned Somerequirements, identified as "if implemented," are conditional If amanufacturer provides that component or feature, it must complywith the specified standard

PC 2001 eliminates some former requirements because Microsoftand Intel deem them no longer important to the industry or "no

longer relevant in defining the optimal user experience with theWindows operating system," whatever that means

PC 2001 defines requirements intended to support new and

forthcoming technologies implemented in recent Microsoft operatingsystems, including Windows 2000, Windows Me, and Windows XP

PC 2001 places a greatly increased emphasis on legacy-reducedand legacy-free systems Some "legacy" items, such as ISA

expansion slots and device dependence on MS-DOS, are forbiddenentirely, while others are merely strongly discouraged

PC 2001 emphasizes (although it does not mandate) features

collectively called the Easy PC Initiative, which focuses on ease ofsetup, use, expansion, and maintenance

You can download a copy of PC 2001 in Word, PDF, or Microsoft

Compiled Help format from http://www.pcdesguide.org

The following sections provide a quick overview of the components andtechnologies used in modern PCs

1.2.1 Hardware Components

One of the great strengths of the PC architecture is that it is extensible,allowing a great variety of components to be added, and thereby

permitting the PC to perform functions its designers may never haveenvisioned However, most PCs include a more-or-less standard set ofcomponents, including the following

and logically into two components The Northbridge controls

cache and main memory and manages the host bus and PCIexpansion bus (the various buses used in PCs are described in

Chapter 3) The Southbridge manages the ISA bus, bridges the PCI and ISA buses, and incorporates a Super I/O controller,

which provides serial and parallel ports, the IDE interface, andother I/O functions Some recent chipsets, notably models fromIntel, no longer use the old Northbridge/Southbridge terminologyalthough the functionality and division of tasks are similar Otherrecent chipsets put all functions on one physical chip

The type of CPU slot or socket determines which processors themotherboard can use The most popular CPU connectors areSocket 370 (current Intel Pentium III and Celeron processors),Socket A (current AMD Athlon and Duron), Socket 478 (currentPentium 4), Socket 423 (old-style Pentium 4), Slot 1 (old-stylePentium II/III and Celeron), Slot A (older-style Athlon), and thenearly obsolete Socket 7 (Intel Pentium and AMD K6-*

processors) Some motherboards have two or more CPU

connectors, allowing them to support multiple processors A fewmotherboards have both Slot 1 and Socket 370 connectors,allowing them to support either type of CPU (but not both atonce)

There are three versions of Socket 370, whichdiffer in pinouts and which processors theysupport Early Socket 370/PPGA motherboardssupport only older Mendocino-core Celeronprocessors Later Socket 370/FC-PGAmotherboards support Coppermine-core PentiumIII FC-PGA processors and Coppermine128-coreCeleron FC-PGA processors The most recentSocket 370 motherboards, which Intel refers to

as "Universal" models, support any Socket 370processor, including Tualatin-core Pentium IIIand Celeron processors

Voltage Regulator Module (VRM)

VRMs supply clean, tightly regulated voltage to the CPU FasterCPUs draw more current Good VRMs are expensive, so somemotherboard makers use the lowest-rated VRM suitable for thefastest CPU the motherboard is designed to support BetterVRMs allow a motherboard to accept faster future CPUs withonly a BIOS upgrade

The type and number of memory slots (along with chipset

limitations) determine the type and amount of memory you caninstall in a PC Most recent motherboards accept 168-pin

SDRAM DIMMs or 168-pin or 184-pin Rambus RIMMs (or both).Many recent motherboards accept 184-pin DDR-SDRAM

DIMMs Older motherboards accept 30-pin and/or 72-pin

SIMMs

Expansion bus slots

The type and number of expansion bus slots determine the typeand number of expansion cards you can add to the system.Most recent motherboards include both PCI and ISA expansionslots, although the latest models may have only PCI slots

Integrated functions

Modern motherboards often include embedded features, such

as video and sound (and, less commonly, LAN and SCSI

interfaces), that were formerly provided by add-on expansioncards The upsides to embedded components are reduced

costs, better integration, and higher reliability The downsidesare that it may be difficult or impossible to upgrade embeddedcomponents, and that you have to pay for those embeddedcomponents whether you use them or not Integrated

motherboards are often ideally suited for casual use, but mostreaders of this book will avoid them for high-performance

systems and build á la carte from discrete components.

Processor

The processor or CPU (described in Chapter 4) is the engine thatdrives the PC The CPU you use determines how fast the systemruns and what operating systems and other software can run on it.Most PCs use processors from Intel (Pentium II/III/4 or Celeron) orAMD (Athlon, Duron, or K6-2/III) Processors vary in speed (currently

(Socket 423, Socket 478, Socket 370, Socket A, Slot 1, Slot 2, Slot

A, Socket 7, and so on), efficiency at performing various functions,and in other respects Although processors get much attention, thetruth is that performance differences between a $50 processor and a

environmentsto 256 MB, which is sufficient for many people Veryfew commercial desktop systems come standard with 512 MB ormore, which is the amount now used by most "power users." AddingRAM is often a cost-effective upgrade for older systems, many ofwhich have woefully inadequate RAM to run modern operating

systems and programs Memory is described in Chapter 5

Floppy disk drive

The humble floppy disk drive (FDD) was formerly used for everything

from booting the PC to storing data to running programs to makingbackups, but has now been largely relegated to such infrequent uses

as making emergency boot diskettes, loading updated device

drivers, running diagnostics programs, or "sneakernetting"

documents to other systems Many people don't use their FDDs fromone month to the next The FDD has been officially declared a

"legacy" device, and many PCs manufactured after mid-2000 do nothave one All of that said, the FDD remains important to millions of

PC users because it is the only read/write removable storage devicepresent on most current PCs Chapter 6 describes what you need to

CD-ROM drive

CD-ROM drives began to appear on mainstream PCs in the early

'90s, are now ubiquitous, and have remained generally unchangedexcept for improvements in speed and reliability CD-ROM discsstore 600+ MB of data in read-only form and, because they are bothcapacious and cheap to produce, are commonly used to distributesoftware and data CD-ROM drives can also play CD-DA (audio)discs and multimedia discs, which makes them popular for listening

to music and playing games CD-ROM drives are detailed in Chapter

10 The chapters following that one cover other types of optical

drives that are becoming common replacements for CD-ROM drives

Chapter 11 describes CD-R and CD-RW drives, which allow you tomake your own CDs Chapter 12 describes DVD-ROM driveswhichare the follow-on to CD-ROM, and may be used to watch movies oraccess very large databasesand DVD recordable drives, which

function much like CD writers but store about seven times as muchdata

Hard disk drive

The hard disk drive (HDD) is the primary storage device on any PC.

Unlike RAM, which retains data only while power remains applied,data written to an HDD remains stored there until you delete it HDDspace was formerly a scarce resource that users went to great

lengths to conserve Modern HDDs are so capacious (20 to 100+GB) and so inexpensive (~$4/GB) that most people now regard diskspace as essentially free On the downside, modern HDDs can bedifficult to install and configure, particularly in older systems, andtheir huge capacity makes some form of tape backup (Chapter 9)almost mandatory Chapter 13 and Chapter 14 tell you everythingyou need to know about HDDs

Video adapter

A video adapter, also called a graphics adapter, accepts video data

display In addition to image quality, the video adapter you use

determines the sharpness, number of colors, and stability of theimage your monitor displays Most recent video adapters display textand simple graphics adequately, but video adapters vary greatly intheir suitability for use with graphics-intense software, including

games Video adapters are covered in Chapter 15

Monitor

The monitor you use ultimately determines the quality of the videoyou see Monitors are available in a wide variety of sizes,

capabilities, features, and prices, and choosing the right one is not atrivial decision Monitors are covered in Chapter 16

Sound adapter and speakers

All PCs can produce basic warning sounds and audible promptsusing their built-in speakers, but for listening to audio CDs, playinggames, watching DVDs with full surround sound, using the Internet

to make free long-distance telephone calls, using voice-recognitionsoftware, and other PC audio functions, you'll need a sound card (orembedded motherboard sound adapter) and speakers or

headphones Sound cards are covered in Chapter 17, and speakers

in Chapter 18

Keyboard and mouse

PCs use several types of devices to accept user inputkeyboards forentering text; mice, trackballs, and other pointing devices for working

in the Windows graphical environment; and game controllers forplaying modern graphical computer games and simulations Thesedevices are covered in Chapter 19 through Chapter 21

Communications ports

Communications ports allow a PC to connect to external peripheralssuch as printers, modems, and similar devices Serial ports, which

in Chapter 25 Parallel ports, which are still commonly used to

connect printers, are covered in Chapter 23 Universal Serial Bus(USB) ports, which are gradually replacing legacy serial and parallelports, are covered in Chapter 24

Case and power supply

The case (or chassis) is the outer shell that contains the PC and all internal peripheral devices The power supply provides regulated

power to all system components and cooling air flow to keep

components from overheating Cases are described in Chapter 25.Power supplies are covered in Chapter 26 Chapter 27 tells you whatyou need to know about protecting the power that runs your PC

1.2.2 Software Components

Many people think of a PC as comprising solely physical hardware, buthardware is just a useless pile of silicon, metal, and plastic unless you

have software to make it do something Software is a set of detailed

instructions that allows a computer to perform a task or group of tasks.Software is usually categorized as one of three types:

deleted file Hundreds of thousands of applications programs areavailable, from comprehensive office suites like Microsoft Office, tovertical market packages like medical office billing software, to

single-purpose utilities like WinZip Whatever you might want a

computer to do for you, you can probably locate applications

software that will do it

An operating system is software that manages the PC itself,

providing such basic functions as the ability to write and read datafrom a disk or to display images on the monitor A PC can run any ofdozens of operating systems, including DOS, Windows

95/98/98SE/Me (we use Windows 9X to refer to these collectively throughout the book, and Windows 98 inclusively if we are

discussing all versions of Windows 9X other than Windows 95),Windows NT, Windows 2000, Windows XP, Linux and other Unixvariants, NetWare, BeOS, and many others The operating systemyou use determines which applications programs you can run, whichperipherals you can use (not all operating systems support all

peripherals), which technologies are available to you (e.g., NT doesnot support Plug-N-Play or USB), and how reliable the system is.The vast majority of PCs run Windows 95/98/Me/NT/2000/XP, atleast for now, so those are the operating systems we focus on in thisbook However, as we write this, Linux has begun to make seriousinroads as a desktop OS, so we expect that future editions of thisbook will focus increasing attention on Linux

Device drivers

We said that the operating system determines which peripherals youcan use That's true, but only indirectly Operating systems

themselves natively recognize only the most basic, standardizedsystem componentsthings like memory, the system clock, and so on

Device drivers are small programs that work at a very low level to

integrate support for other devices into the operating system Using

device drivers allows an operating system to be extensible, which

means that support for new devices can be added incrementally,without updating the operating system itself For example, if youinstall a new video card, installing a device driver for that video cardallows the operating system to recognize it and use its full

capabilities Most operating systems include "vanilla" device driversthat allow devices to be used at less than their full capabilities (e.g.,the standard VGA driver in Windows) until an appropriate driver can

be installed Most operating systems also include specific device

1.2.3 Firmware Components and the PC BIOS

Firmware is a special class of software, so called because it is more-or-less permanently stored on chips Firmware is often referred to

generically as a BIOS (Basic Input/Output System) because the only firmware contained in early PCs was the main system ROM-BIOS (Read-

Only Memory BIOS) That's no longer true Nearly every component in a

modern PC contains its own firmware Disk drives, SCSI host adapters,video cards, sound cards, keyboards, and most other devices containfirmware, and nowadays that firmware is seldom read-only

Although few people do so, installing firmware updates is an important part of keeping a modern PC functioning at its best.

For example, firmware for most CD writers is frequently updated to add support for new types of blank media The most important firmware to keep updated is the main system BIOS.

Good motherboard makers frequently release updated BIOS versions that add functionality, fix bugs, support faster

processor speeds, and so on.

The two most important pieces of firmware in a PC are the chipsetwhichtechnically is intermediate between hardware and firmwareand the mainsystem BIOS The chipset is the heart of the PC Its capabilities

determine such fundamental issues as which processors the

motherboard supports, how data is communicated between processorand memory, and so on The BIOS manages the basic configuration

information stored in non-volatile CMOS memory, such as the list of

installed devices, and controls many of the low-level configuration

parameters that determine how the PC functions Although the chipset isnot updatable, the BIOS is updatable in all modern PCs

Pentium II motherboards did not support Celerons, which use a differentL2 caching method Similarly, a motherboard manufactured when thefastest Pentium III available was 600 MHz might have no settings to allowfor faster Pentium IIIs Installing an updated BIOS fixes problems likethese Systems with Flash BIOS (which is to say, all modern systems)can be updated simply by downloading the new BIOS and running a

special installer program

Updating a flash BIOS is a nontrivial operation Performing the update incorrectly or losing power during the update can leave the PC incapable of booting Read the detailed instructions supplied by the manufacturer before you attempt to update your BIOS, and if possible connect the PC to a UPS during the BIOS update Some motherboards, notably recent Intel models, have

a BIOS recovery function that allows for correcting a failed update simply by changing a jumper and running the update procedure again Some motherboards have a dual BIOS, which means that if you damage one BIOS during an update, you can boot the system from the other and repair the corrupted BIOS.

But many systems make no such provision, so be extremely careful when updating your system BIOS If you fail to follow instructions exactly, or if you accidentally install the wrong BIOS update, or if the power fails during the update, the only solution may be to return the motherboard to the manufacturer for repair

or replacement.

You configure BIOS options and chipset settings by running a specialfirmware program called CMOS Setup, which is usually invoked by

pressing F1, F2, or Delete while the system is booting Some systemsallow the administrator to password-protect access to CMOS Setup,

Setup.CMOS Setup programs vary at the discretion of the motherboard

or system maker in terms of what they allow you to access and change.Some Setup programs provide essentially complete access to all

superb The BIOS Companion (http://www.electrocution.com/biosc.htm)documents BIOS and chipset options in great detail, including some thateven we don't understand Every PC technician should own a copy of thisbook Another very useful BIOS resource is Wim's BIOSPage

(http://www.wimsbios.com/)

1.2.4 Technologies