Core Components
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Part 1
Core Components
◆ Chapter 1: Five Easy Pieces: PC Hardware in a Nutshell
◆ Chapter 2: Inside the PC: Core Components
◆ Chapter 3: Taking Apart and Rebuilding the PC
◆ Chapter 4: Avoiding Service: Preventive Maintenance
◆ Chapter 5: Installing New Circuit Boards
◆ Chapter 6: System Memory
◆ Chapter 7: Power Supplies and Power Protection
COPYRIGHTED MATERIAL
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Chapter 1
Five Easy Pieces: PC Hardware
in a Nutshell
◆ CPUs, Peripherals, and Controllers
◆ Buses and Interfaces
◆ The Sixth Piece: Drivers
◆ Other PC Components and Issues
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FIVE EASY PIECES: PC HARDWARE IN A NUTSHELL
Introduction
If you have any experience buying, using, or fixing PCs, you’ve no doubt heard a bushel of strange
terms—RAM, CPU, USB, PCI, FireWire, Athlon, Duron, Pentium, Celeron, Itanium, Centrino, you
name it. Even more daunting is figuring out which acronyms—and again, there are a ton—to pro-
nounce and which ones you simply spell out. For example, USB and CPU aren’t words (you just spell
out the letters), but RAM is “ram” and SCSI is “skuzzy.” Don’t expect the slang to get better any time
soon, because this business loves jargon.
Since their introduction in the ’80s, PCs have evolved nonstop. The most recent changes are bringing
them more closely in line with consumer electronics such as video cameras, DVD players, mobile com-
munications devices, and televisions. Standards seem less chiseled in stone and more written in shifting
sand. Consumer electronics and PCs haven’t really been able to talk to one another for very long.
But technology is rapidly moving toward a digital, wired (or wireless, if you prefer) world. With
the advent of wireless technology, your notebook computer will automatically link up to your desk-
top computer, and while you’re trying to figure out what’s for dinner, your laptop will update the
files on your desktop. You’ll also be able to turn on the television with a single keystroke on the PC
keyboard, and your PC’s hard drive or recordable DVD drive will automatically record a television
show while you work on a Microsoft Excel worksheet. Different companies are coming up with dif-
ferent ways to implement this type of technology, fueling a rapid-pace change in hardware and
increasing the number of “standards.”
Another common trend in recent years has been to put add-on hardware boards, such as video and
sound cards and even modems, right on the motherboard to save a little extra money in production.
Consolidation is a major theme; some major computer manufacturers sell computers with no expan-
sion slots. Their reasoning is that any add-on hardware that’s required can be attached via the Uni-
versal Serial Bus (USB) port.
If you don’t know already, the motherboard is the central board in a PC to which everything else
ultimately connects. The motherboard has a socket or slot for the Central Processing Unit (CPU),
expansion slots to add other hardware boards that control features such as video and audio, ports to
which devices such as your mouse connect, sockets for adding extra random access memory (RAM),
USB and FireWire ports for attaching a multitude of peripherals, and connectors called Integrated
Drive Electronics (IDE) channels for plugging in hard drives, CD-ROM drives, and DVD drives.
You’ll learn a lot more about them in Chapter 2, “Inside the PC: Core Components.”
PC hardware can be confusing because there are so many parts to a PC—and some of these parts
change pretty quickly. I wish I could write this book so that it completely avoids the geeky details
such as, “USB version 1.1 supported speeds of 12 Mbps, whereas USB 2.0 supports 480 Mbps per
second in order to compete better with FireWire,” but ultimately you’ll have to know some of that
stuff or you won’t really be effective as a buyer, upgrader, or fixer. Jumping in at that level right
now, however, would probably convince the average reader that quantum physics would be a sim-
pler course of study.
Knowledge really is power where computers are concerned. What you need, then, is some struc-
ture, along with a bird’s-eye view of PC hardware. It’s a lot easier to understand some new term if you
have a classification system. What I’m going to explain in this chapter is the mental model that I use
to understand PC hardware. It’s not perfect—not everything will fit into this model—but I think you’ll
find it useful in your hardware education.
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CPUS, PERIPHERALS, AND CONTROLLERS
5
CPUs, Peripherals, and Controllers
Basically, PC hardware boils down to three kinds of devices: the CPU (or, as more and more machines
offer multiprocessor capabilities, the CPUs), peripherals (the input, output, and storage devices that
make a computer functional and user-friendly), and in-between devices that I’ll generically call con-
trollers or adapters.
For example, consider what makes it possible for the PC to put images on your video monitor. Every
PC has a video monitor, and every PC also has a chip inside it called the CPU, often called the processor,
which is essentially the “engine” of the PC. When you hear people say they have a “Pentium 4 com-
puter,” they’re describing the particular model name of the CPU around which their computer is built.
Common CPU names you might hear are Pentium (in various flavors, such as II, III, or the non-Roman
numeric 4), Celeron, or Pentium M (which is the CPU brain of the popular mobile Centrino chipset); all
of these are CPUs made by Intel. At one time, Intel had a monopoly on this market until other compa-
nies decided they could make CPUs faster and cheaper. These competitors include Advanced Micro
Devices (AMD) with its Athlon, Duron, Sempron, and Opteron processors, and VIA Technologies,
which markets the Cyrix MII, C3, and Eden chips.
In between the CPU and the monitor is a kind of diplomatic device—a circuit that knows how to
talk to both the CPU and the video monitor—called the video adapter or video controller. If you ever see
a reference to an S3 graphics adapter, a Super VGA (SVGA) adapter, or a 3D adapter, it’s a reference
to a video adapter. Video adapters contain memory that they use to retain the current video image,
as well as onboard electronics that know how to do many useful graphical tasks such as drawing
lines, circles, and polygons. Why is this important? Well, if you’re ever in the middle of a World War
II dogfight fighting for your life (in a PC game, of course), you really want your graphics to be smooth.
One of the most important specifications today for 3D video cards is how fast they can draw a simple
geometric shape called a polygon—measured in millions of polygons per second.
Interestingly, a large number of companies used to build video controllers, as well as components
for other manufacturers’ video controllers. However, with the price erosion of high-performance
graphics controllers in the latter part of the ’90s, many of these companies either quit making graphics
controllers or made them only to sell to computer manufacturers for integration into motherboards.
The result: fewer third-party video adapter boards for sale at the consumer level.
You’ll see this CPU-adapter or controller-peripheral connection throughout all PC hardware;
for example:
◆ Figure 1.1 shows speaker connections on a motherboard, and Figure 1.2 shows a Creative Labs
Sound Blaster Audigy sound card. These illustrate the two kinds of sound systems used on com-
puters since the early ’90s. The first one is the small PC speaker that’s attached directly to your
motherboard. It doesn’t make any cool noises, just simple beeps. The other is attached to special
stereo sound circuitry that might also be built on the motherboard or on a separate circuit board
that you plug into your motherboard. Once just cheap multimedia components, PC sound sys-
tems have risen in technology and performance, rivaling consumer audio.
◆ Most motherboards today have built-in circuitry to control Enhanced Integrated Drive Electron-
ics (EIDE) hard drives, CD-ROM drives, and DVD drives. In fact, over 85 percent of all drives
being used in PCs today use the EIDE interface. Because of the prominence of the EIDE interface
(which is discussed in more detail later in this chapter), you might have to install a special
adapter if you want to connect another kind of drive to your system. For example, if you want
to install a Small Computer System Interface (SCSI) hard drive, you’ll need to install a special
SCSI adapter (also called a host adapter) in one of the expansion slots on your motherboard.
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Figure 1.1
The PC speaker and
its connection on the
motherboard
Figure 1.2
A Creative Labs
Sound Blaster Audigy
sound card
◆ To connect a printer to the PC, you’ll need a parallel port or USB port.
◆ If you’re connecting a scanner or a digital camera to your computer, you’ll probably use one
of your PC’s USB ports.
◆ To use your computer as a video-editing bay, you connect your digital video camera to your PC’s
FireWire port—which is an ultra-fast way to transmit digital data from one device to another.
These are just a few examples of the different types of electronic components; you’ll see tons more
in this book.
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BUSES AND INTERFACES
7
Buses and Interfaces
But wait, you’re not done yet. You have three parts of my PC model down—CPUs, peripherals, and
controllers/adapters. I’d better explain two more pieces that I’ve already mentioned: buses and interfaces.
Let’s say you’re talking to a friend who just bought a new computer. Lapsing into fluent comput-
erese, your friend says, “Hey, I just got this 3.2-gigahertz Pentium 4 with a gig of RAM, a 300-gig serial
ATA hard disk, and an AGP 8X video card with 512 megs of RAM with DVI.” Notice how your friend
describes the computer—the first thing mentioned was a “3.2-gigahertz Pentium 4.” As you’ve
already read, “Pentium 4” describes the CPU, the chip around which the entire computer is built.
Some people compare it to a car’s engine—not a terrible analogy, with gigahertz being vaguely anal-
ogous to horsepower—but I’ll take up CPUs in greater detail in Chapter 2.
The next part of the statement, “a gig of RAM, 300-gig hard disk, and AGP 8X video,” refers to
hardware other than the CPU—hardware that helps to make the computer useful. RAM is the com-
puter’s memory, a bunch of electronic chips that the CPU uses to store the program and data on which
it’s currently working. (RAM isn’t a very useful acronym. What we ought to call it is “chips that the
CPU can both store data to and read data from,” but I suppose that would make for far too long an
acronym.) I’ll introduce RAM in Chapter 2 and discuss it in some detail in Chapter 6, “System Mem-
ory.” What about “300-gig hard disk”? Well, “300 gigs” (gigabytes, or a billion bytes) describes the
amount of data-storage space the computer has on its hard drive. This is memory that will remain
intact even after the computer has been shut down. Many explanations of computers show simple
block diagrams that look something like Figure 1.3.
So that PCs can be easily upgraded, PC manufacturers put empty electronic connectors inside each
PC; most people call them expansion slots. The expansion slots are the easily visible part of the bus,
which communicates with the CPU. Over the years, several bus types have become popular. The most
common internal bus nowadays is Peripheral Component Interconnect (PCI). (Don’t worry about this
now—I’ll take it up in detail in Chapter 2.) Most motherboards today have these PCI expansion slots;
some also include another (older) type of bus, called Industry Standard Architecture (ISA). Figure 1.4
shows a motherboard with both of these kinds of slots. Fortunately, their designs make it impossible
to plug an expansion card into the wrong type of socket. But you still need to know what types of
cards your motherboard will accept before going out and buying that great video card upgrade!
Figure 1.3
The CPU is logically
connected through the
motherboard to its mem-
ory, hard disk, video dis-
play, and printer.
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Figure 1.4
Notice the PCI and ISA
expansion slots on this
Pentium motherboard.
PCI
ISA
Why are there PCI and ISA bus connectors in this computer? Because they’re both standards on
which computer system designers and computer expansion board designers can agree. This is important
because, just as the standard electrical sockets in your home’s walls make it easy for you to buy appliances
with electrical plugs and immediately use those appliances, a standard bus connector such as PCI or ISA
means you can buy your PC from one vendor and your sound card, display board, or internal modem (to
name just a few examples) from another vendor and still be pretty sure they’ll work on your PC.
The mildly tentative tone of the previous sentence reflects that hardware compatibility in the PC
world is sadly not a sure thing, and even the biggest names in the PC business sometimes sell hard-
ware that just plain doesn’t do what it’s supposed to do. However, the industry is continually evolv-
ing, and few hardware incompatibility issues remain.
TIP
One piece of trivia you might find helpful to remember: The newer the PC motherboard, the fewer
the number of ISA devices that will be supported by it. Most new motherboards have no ISA connections
at all. The ones that do just have one dual ISA/PCI slot along with lots of PCI slots. ISA was provided for
many years for backward compatibility, but it’s on its way out because of the prevalence of faster buses.
By now you might be wondering exactly who sets the standards for how PCs are designed.
Sadly, the answer in most cases is that there are a lot of cooks in the kitchen, and that makes stan-
dards seem less than well, standard. Two of the most important cooks are Microsoft and Intel
(sometimes referred to together as Wintel). Almost every year, the companies issue a set of design
guidelines that spell out the minimum requirements that a PC must have to carry the label
“Microsoft Windows compatible.”
Although many current video boards connect to the CPU through a PCI interface, one of the main
features that drives innovation in the computer business is speed: the faster the CPU and video con-
troller can blast pictures onto the screen, the more popular the computer is likely to be. So when some
in the industry became impatient with PCI’s top speed (not fast enough!), Intel decided to add
another bus—for graphics boards only—that the computer could use instead of PCI. This ushered in
the Accelerated Graphics Port (AGP) standard. Thus, when you read an ad saying that a computer
has AGP video, it means there’s a connector inside the PC that’s designed to offer higher speed than
PCI, and the system uses an AGP-compatible video controller.
You’ve learned about CPUs, peripherals, controllers, and buses; now what about interfaces?
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ACTUALLY, THERE’S A SIXTH PIECE
9
NOTE
The first AGP controllers offered a speed of 1X or 2X, but the faster 8X controllers are now on
the market, along with the motherboards that support them. The fastest AGP specification is cur-
rently version 3.0. The original AGPs weren’t a lot faster than using a PCI video board, but using AGP
video meant you freed up a PCI slot. The 8X refers to a much faster rate of transfer from the video to
the CPU and back again, something that’s finally helping to end some of the video-speed bottle-
necks that most people have experienced.
Just as standard buses such as PCI make it easy for one vendor to offer a PC and another vendor
to offer a disk controller, there’s also a standard interface between the disk controller and the disk. For
historical reasons, there’s more than one way to connect a disk to a disk controller. The most common
disk interface used today is the EIDE interface. EIDE is so popular, in fact, that virtually all mother-
boards have two EIDE controllers built right into them. Each EIDE controller can accommodate up to
two EIDE drives (either hard drives or CD-ROM/DVD drives).
The EIDE standard for the past several years has been a parallel bus structure called Ultra ATA.
Although it’s been serviceable for most users, today’s computers require faster data transfers to and
from the hard disk. Because of the physical limitations of the Ultra ATA design, a newer standard
called Serial ATA has been developed. It’s fast and self-configuring, supports hot plugging, uses less
power, and is easy to configure. I’ll talk about more Serial ATA specifics in Chapter 10, “Understand-
ing and Installing ATA Drives.”
How are CPUs, buses, adapters, interfaces, and peripherals connected? Does one have to go with
another? For example, will you find that SCSI adapters are available only for PCI? Not at all. As far
as I know, SCSI adapters are available for every bus around, with the exception of AGP. Five easy
pieces, then: CPUs, buses, controllers/adapters, interfaces, and peripherals. The CPU does the
thinkin’, the peripherals do the doin’, and the controllers/adapters help them communicate. Buses
and interfaces are just the glue that sticks them all together.
Actually, There’s a Sixth Piece
Buying all of this hardware is of no value if you can’t make it all work. As you probably know, com-
puter hardware is of no value if there isn’t software to control it. So, in a sense, there’s a sixth piece to
my five-piece model: software that’s designed to control specific pieces of hardware. These pieces of
software are called drivers.
The best hardware in the world is no good if your operating system and applications don’t support
it. The question of whether a particular piece of hardware has drivers for, say, Windows XP, Win-
dows Millennium Edition (Me), Windows 2000, Windows Server 2003, or Linux is of vital importance
when you’re buying new hardware. Most newer operating systems offer formal or informal hard-
ware compatibility lists—a roster of hardware directly supported by that operating system version.
At the least, they’ll have notes about devices known to have problems when used with that operating
system. (Sometimes they include suggested workarounds, too.) You should find this information for
your operating system before you shop for any new piece of hardware. Buying and trying unsup-
ported hardware can make for a long walk down a lonely road—such hardware might work just as
well as one that’s supported, but it might also require a lot more work on your part. So check with
your software vendor before falling in love with some new doodad.
NOTE
You can access Microsoft’s Windows Catalogs and Hardware Compatibility Lists for the entire
family of Windows operating systems at www.microsoft.com/whdc/hcl/default.mspx. Older
Microsoft operating systems had an HCL, but Windows XP, Windows Server 2003, and Windows 2000
use a more interactive Windows Catalog. It does the same thing that an HCL did, just better.
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Real-World Advice
Make sure the hardware you buy is compatible with your operating system. If not, you could be in for a lot
of headaches trying (and failing) to get your new hardware to work!
Typical PC Components and Issues
At this point, you might be thinking, “Yes, I’ve heard of Pentium 4, gigahertz, EIDE, and AGP, but
that’s not all I’ve heard of—what about BIOS, Ethernet, or FireWire connections?”
The intention of this chapter is to introduce you to several basic PC terms and help you start to
organize the concepts of PC hardware in your mind—but first I needed to explain the five-part model.
Now that you’re comfortable (I hope!) with the terms CPU, bus, adapter/controller, interface, and periph-
eral, I can round out the chapter with five-second explanations of the most significant PC terms.
I’ll discuss most of these terms again in greater detail later in this book. For now, though, Table 1.1
will serve as a good warm-up of terms you need to know.
What you see in Table 1.1 are PC features, a few common examples of each feature, and a brief bit
of why you should care about each feature. Following the table, Figure 1.5 identifies some of the con-
nectors you’ll see on the back of your PC.
Table 1.1:
PC Pieces
Feature
Typical Examples
Brief Description
AGP bus
Brown expansion slot
This bus is designed specifically for use with video boards.
on the motherboard for
video adapters.
Basic input/
American Megatrends
BIOS is the most basic control software for your computer.
output
Incorporated (AMI), IBM,
The BIOS is what makes a PC IBM compatible. It tells the
system (BIOS)
Compaq, Phoenix, Award.
computer how to look at the bus, memory, and floppy drive
manufacturer
and how to read other programs. The BIOS isn’t a plug-in
card; it’s a chip that’s mounted right on the motherboard.
Bus type
PCI, PCI Express, PC
The bus determines what kind of expansion circuit boards will
Card (formerly known as
work in the machine. As with a CPU, a major bus characteristic is
PCMCIA), CardBus, PC bus
speed. Boards built for one bus generally will not work on other
(8-bit ISA), AT bus (16-bit
buses, so the second main bus characteristic is compatibility.
ISA), proprietary 32-bit,
(Having a PC with the fastest bus in the world is no good if no one
16- or 32-bit Micro Channel
makes boards that work in that bus.) PC Card and CardBus are
Architecture (MCA), EISA,
mainly used in laptops; most current desktops use PCI and AGP,
Local or VESA bus, AGP,
but PCI Express is gaining popularity. You’ll find that most
FireWire.
controllers come in versions for any kind of bus.
Cache
256 kilobytes (KB), 512KB,
RAM is slower than most CPUs, making memory speed an
1 megabyte (MB).
important system bottleneck. Faster memory exists, but it’s
expensive. PCs compromise by including just a small amount
of faster memory, called cache. If it’s on the motherboard, it’s
called level 2 (L2) cache. Many processors include their own
cache, which is called level 1 (L1) cache.
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TYPICAL PC COMPONENTS AND ISSUES
11
Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
Cartridge
Iomega Jaz, Zip drives, Shark
These work like hard disks but are usually a bit slower. Their
storage device
drives, Syquest drives,
main feature is that they’re reasonably priced backup devices.
Castlewood Orb drives.
Some attach to a parallel port, some to EIDE, and others to SCSI
or USB.
CD-ROM
EIDE, SCSI.
CDs are the basic means for distributing programs and data
drive speed,
today. For less than $1/CD, a vendor can provide the equivalent
interface
of about 600 books of text. CD-ROM drives are the peripherals
that make it possible to read those CDs. With a CD-ROM drive,
speed is a relative thing. If you’re using it to read text files or
load software, a slower drive (around 16 by today’s standards)
will do. But if you’re using it to play games, then you want the
fastest CD-ROM drive you can get (52 plus).
CD recordable
IDE, EIDE, SCSI, USB,
A CD-R drive permits the one-time (recorder) writing of a CD,
(CD-R)/CD
FireWire.
and a CD-RW drive permits the multiple (rewritable) writing of a
rewritable
CD. Both are usually used for data storage or writing a program or
(CD-RW) drive,
music for distribution. A CD can hold more than 720MB, but
also called CD
most CD-Rs write no more than 650MB (and CD-RWs even
burner
less, 440–550MB). These drives can also be used like a regular
CD-ROM drive to install software and play audio CDs. USB
versions are external and can easily be shared between multiple
PCs (as long as all have at least one USB port).
Configuration
Typically built into the system
Computers won’t work until you tell them about themselves,
method
startup software.
or configure them—which you do by changing the BIOS
configuration operation for your system. Today, virtually all
computers configure themselves using built-in software in
the BIOS. In some cases, you might need to set a few jumpers
to configure CPU voltage levels, bus frequency, and cache
memory on the motherboard.
CPU type
Pentium, Pentium
The CPU determines how much memory the system can
Pro, Pentium II, Pentium III,
address, what kind of software it can run, and how fast it can
Pentium 4, Celeron,
go. The main difference in modern processors is speed, but
Centrino, Itanium, K5, K6,
newer ones have other capabilities such as better graphics
Athlon, Duron, Alpha.
handling and multiprocessor support.
CPU speed
100 megahertz (MHz)–3.20
MHz and GHz are rough measures of system speed. All other
gigahertz (GHz) and getting
things being equal, a 1GHz processor would run twice as fast
faster every day!
as a 500MHz processor. However, because so many other
components affect the speed of your computer, doubling the
CPU speed never actually doubles the system speed.
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Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
DVD drive
IDE, EIDE, SCSI, USB,
As far as computers are concerned, a DVD drive is basically
FireWire.
the next step after a CD-ROM drive. DVDs look like CDs, but
DVDs can store more than 26 times as much data as CDs.
DVDs can store as much as 17 gigabytes (GB), depending on
the model drive and DVD you use.
DVD
DVD-R, DVD-RAM,
DVD-RAM drives are similar to CD-R drives but are for the
recordable
DVD-RW, DVD+RW.
higher capacity DVD format. DVD-RAM lets you record as
(DVD-R)
much as 4.7GB of data per DVD side.
drives, also
called DVD
burners
Floppy disks
51⁄4˝: 1.2MB; 31⁄2˝: 1.44MB,
Floppy disks (also called floppies) are low-capacity removable
2.88MB (unusual); LS-120.
media used to make your data portable. Today, because files
are getting larger and larger, many computers aren’t shipping
with a floppy drive but instead with a Zip drive or some other
high-capacity drive. The most common floppy drive today
holds 1.44MB (just under a million and a half bytes) of data. Zip
drives, by contrast, hold 100 or 250MB—about the same as
hundreds of floppy disks. Floppies are driven by circuits called
floppy controllers, and they interface with these controllers
through a standard connector on a 34-pin ribbon cable.
Hard disk/
Advanced Technology
The interface controller allows your computer to communicate
storage
Attachment (ATA)/IDE, Serial
with your hard drive, CD-ROM drive, and DVD drive. Most
adapter
ATA (SATA), EIDE, SCSI.
systems today use EIDE because it’s inexpensive, easy to install,
and fast. EIDE uses a 40-pin cable to interface with drives. The
terms IDE and EIDE are often replaced by ATA in common
terminology, but they’re all the same. An ATA-33 drive with
33MB per second (MBps) throughput (simply put, how fast data
moves to and from the drive) is the same as an Ultra DMA/33
drive, which is the same as an Ultra ATA/33 drive. ATA/100
drives offer 100MBps throughput, and the newer Serial ATA
standard can transfer data at 150MBps.
IEEE 1394
Typically available as a
FireWire is a newer external bus standard that’s much faster
(FireWire)
built-in port.
than traditional bus options, allowing for a maximum data
transfer speed of more than 400Mbps (megabits per second).
FireWire has many possible uses, but it seems to be most popular
for connecting digital video cameras, where fast real-time
transfer of huge amounts of digital data is necessary.
ISA bus
Older, black expansion slots
Used for old expansion cards, including modems, sound cards,
on the motherboard.
and port expanders (additional serial and parallel ports).
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TYPICAL PC COMPONENTS AND ISSUES
13
Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
Keyboard
Various input typing devices.
Keyboards have a controller on the PC’s main board, and most
use either a mini-DIN (PS/2) or a USB. Some old keyboards use a
full-sized DIN interface called an AT-style connector—a reference
to the original IBM AT. Most new keyboards are compatible, and
you have a choice about what kind of shape, color, size, and
ergonomics you prefer.
Local Area
Ethernet, Token Ring, FDDI,
LANs allow PCs to communicate with each other and share
Network (LAN)
ATM, Attached Resource
data and printers. To do this, each PC on a LAN needs a
board
Computer Network
network interface card (NIC). There are several types of NICs,
(ARCNet).
including Ethernet, Token Ring, Fiber Distributed Data
Interface (FDDI), and Asynchronous Transfer Mode (ATM).
Ethernet is the most common. Most businesses have LANs,
and more and more homes are adding LANs as they acquire
two or more PCs. Home and small-business LANs are often
wireless, which means that the LAN card connects to the
network without cables—typically via radio frequency (RF)
signals or your home phone line.
Memory (RAM)
64MB, 96MB, 128MB, 256MB,
This is the workspace PC’s use for the software they’re
512MB, 1024MB (1GB).
currently processing. Newer software generally requires more
RAM than older software.
Memory
Dynamic RAM (DRAM),
Although RAM is slower than most CPUs, memory chip
(RAM) type
Extended Data Out (EDO),
vendors have been working hard to try to bridge that gap.
synchronous DRAM (SDRAM),
The fastest current kind of main memory is called SDRAM.
Rambus DRAM (RDRAM),
It’s preferable in new systems. Although traditional RAM
Double Data Rate SDRAM
operated at 100MHz, newer forms operate at 200MHz and
(DDR SDRAM), DDR2.
faster to match faster motherboard clock speeds. RDRAM is
a common standard, as is the less-expensive (but still fast)
DDR SDRAM and DDR2. By the way, memory usually
connects to the CPU through a proprietary bus, rather than
PCI or some other standard.
Modem
300 baud, 9600 bits per
Analog communications devices, allowing computers to
second (bps), 33.6 kilobits
connect to each other. Modem speeds are pretty much maxed
per second (kbps), 56kbps.
out, and newer types of connections—such as a cable modem
and digital subscriber line (DSL)—are now much more popular.
It’s estimated that over half of Internet users are using a high-
speed connection as opposed to a modem. Five or ten years
from now, modems may go the way of the 51⁄4˝ floppy drive.
Mouse
A variety of rolling devices,
Designed to make computing easier by allowing people to
including mice and rollerballs.
“point and click.” A key part of the Windows Icon Mouse
Pointer (WIMP) interface.
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Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
Number of
4 or 8. (Only very old PCs
Usually, the only thing talking to your memory is the CPU.
direct memory
have just four.)
Information stored in RAM is read by the CPU, and the CPU uses
access (DMA)
RAM to store information. However, some devices such as hard
channels
drives take a (relatively) long time to move data back and forth.
supported
And if the computer needs to act as the go-between for this data,
the CPU can get bogged down in the process. DMA lets certain
devices to communicate directly with RAM (main memory),
allowing the CPU to attend to other processes while the hard
drive, for instance, transfers data to RAM. Using DMA to handle
data transfer between many of the external devices and RAM
really improves the overall processing speed of your computer.
Number of
3–10.
The more the merrier. Many big-name computers sport only
expansion slots
three expansion slots. As the popularity of USB devices
increases, expect to see fewer and fewer expansion slots.
Number of
8 or 16. (Only very old PCs
For the computer to use its peripheral devices, it needs to know
peripherals
have 8.)
when a device has information for it. For example, if you press a
supported
key, the keyboard has to have a way to get that information to the
computer. In the past, computers would get this information by
polling their external devices (looking first at one device, then the
next, and so on, repeating the process many times per second).
The trouble is, this takes up a lot of computing time, and early
microcomputers had little power to spare. So the engineers who
developed the microcomputer changed to a new system that
uses interrupts. Interrupts (also called interrupt requests—IRQs)
are associated with the external devices. When a device has
information for the computer, it signals the CPU through its
interrupt line. The problem is, generally no two devices can
share an interrupt. This means when you’re configuring your
system, you need to make sure you don’t assign the same
interrupt to two or more devices. Doing so will cause those
devices to have a conflict and can make the system crash—or at
least not recognize the devices.
Parallel port
Unidirectional, bidirectional,
The parallel port is the basic adapter for printers and external
enhanced parallel port (EPP),
drives such as Zip and CD-R/RW drives. The interface uses a
and enhanced capabilities
connector called a Centronics connector at the printer end and
port (ECP).
what’s known as a DB25 connector on the computer end. In its
simplest form, the parallel port is unidirectional—data goes
from the computer to the printer and not the reverse. Most
current parallel ports now also support bidirectional data flow—
data can go back and forth between the computer and the
parallel device—and higher data transmission speeds.
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TYPICAL PC COMPONENTS AND ISSUES
15
Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
PCI bus
White expansion slots on the
Used for a variety of peripherals, including video cards, sound
motherboard.
cards, modems, and SCSI host adapters. A common standard
today, it’s gradually being phased out for the newer PCI Express.
Plug and
PC systems are identified as
PnP is a standard that allows a computer to automatically
Play (PnP)
being either PnP compatible
identify and configure devices you want to add to the system.
compatibility
or not. (Only ancient
To have PnP work, your BIOS and operating system must
computers, called legacy
support it (most new ones do), and you must have PnP
systems, don’t support PnP.)
hardware. Also, a newer type of PnP, called Universal PnP, is
available in Windows XP; Universal PnP extends the PnP
concept to the network, enabling automatic discovery and
control of network devices and services.
Printer control
Epson codes, HPPCL
Printer control languages tell your printer how to underline
language
(LaserJet commands),
words, put pictures on the page, and change typefaces.
PostScript, others.
Serial port
COM1, COM2, COM3, COM4.
Serial ports are adapters that support a wide variety of low-speed
peripherals, including modems, serial mice, digital cameras,
Personal Digital Assistants (PDAs) such as the Palm Pilot, and
some kinds of scanners. They connect to peripherals using an
interface called RS-232, which most commonly uses a male DB25
or DB9 connector. Generally regarded as old and slow.
Serial port
8250, 16450, 16550, 16650,
The UART is the main chip around which a serial port or
Universal
16750, 16950.
internal modem is built. The 16550 UART is no longer the
Asynchronous
fastest, but it’s still commonly used for high-speed
Receiver/
communications and communications in multitasking
Transmitter
environments. Software supports fast serial ports through
(UART)
a first-in, first-out (FIFO) buffer. The 16550 UART offers 16-
byte FIFO, the 16650 offers 32-byte FIFO, the 16750 offers
64-byte FIFO, and the 16950 offers 128-bit FIFO.
Sound card
8-bit, 16-bit, 32-bit, 64-bit,
Sound cards support music and sound reproduction on your
128-bit, frequency modulation
PC, but music and sound are represented in an 8-bit, 16-bit,
(FM), Musical Instrument
32-bit, 64-bit, or 128-bit format. The 32-bit format is better,
Digital Interface (MIDI),
but it takes up more space. The sounds are recorded and
wavetable audio interface.
reproduced either with FM synthesis, MIDI control, or
wavetables. Additionally, with the right audio interface
cable, a sound card in combination with the right software
can play music on your PC. The newest sound cards even
support Dolby 5.1, so you can watch your favorite movie using
your computer’s DVD drive and have the same heart-
pounding sound you hear in the theater. The key for
soundcard compatibility is the “Sound Blaster standard.”
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Table 1.1:
PC Pieces (continued)
Feature
Typical Examples
Brief Description
System clock/
Built-in on the motherboard
The system clock keeps the proper time and date and is used
calendar
or added on an expansion
to “clock” various system operations.
board on really old PCs.
USB
Available as a built-in port or
This adapter was first introduced in 1995. It features both
an add-on interface card.
speed and flexibility; one USB interface can support up to
127 devices, including keyboards, mice, scanners, digital
cameras, printers, and modems. USB adapters use a small
proprietary connector as their interface to USB-compliant
peripherals and can often be daisy chained together—
although using multiple USB devices might require the use
of one or more USB hubs (a central connectivity device).
Virtually all new computer systems and all current operating
systems now support the main USB standard. The current
version of the standard—USB 2—is much faster (480Mbps
versus USB1.1 at 12Mbps) and beats out SCSI and FireWire for
drive throughput.
Video board
Video Graphics Array (VGA),
The video board determines how images are displayed on your
SVGA, 8514 Adapter,
monitor. This in turn affects what kind of software you can run
Extended Graphics Array
and how quickly data can appear on the screen. Video boards
(XGA).
vary in the number of colors and pixels (the dots on the screen)
they can display. Most important in modern video boards,
however, is whether they hold video data as a simple “dumb
frame buffer,” which requires that the CPU do all the video
work, or they contain circuitry that can help with the grunt
work of graphical screens. (Boards such as this are called
bitblitter boards.) The main issues in video nowadays are speed,
resolution, and color depth (the number of colors the system
can display at one time). The interface between most video
boards and their monitors is called an analog RGB interface,
where RGB stands for red, green, and blue. Although some of the
newer video boards interface with the new flat-panel displays
with analog boards, more and more of the new flat-panel
displays use a faster digital interface. Among today’s fastest
video boards are those including the 256-bit graphics-
processing unit for optimum 3D graphics performance.
Exerting Your Geekiness Upon Others
Okay, now you have some knowledge of the basics in terms of hardware connections and peripherals. The
one constant in the computer industry is change, and quick change at that. Once you look up the newest
and fastest hardware (or purchase it), it’s basically obsolete. How does one possibly keep up with it all?
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TYPICAL PC COMPONENTS AND ISSUES
17
The answer is, you don’t have to unless you want to. If your job is to fix computers or be the expert on how
many millions of polygons a particular sound card can render per second, then it would probably behoove
you to do your best to keep up by constantly scouring the Internet and trade journals for the latest and
greatest. If, however, you want to be knowledgeable about hardware without devoting your life to mem-
orizing specifications, that’s fine, too. You can be knowledgeable without being obsessive.
Here’s how: Make sure you have a firm, firm understanding of the basics of how computer hardware works.
That’s what this chapter, along with the rest of Part 1 of this book, teaches. Then, periodically take a look at
the market to see what’s out there. If the newest video cards have 512MB of RAM right now, they might have
1GB of RAM six months from now, but the fundamental technology will probably still be the same. At a min-
imum, the technology in terms of how the video card works in relation to the rest of the computer will be the
same. You want to at least be able to have a decent conversation about computers (i.e., know the difference
between a sound card and a video card, and know that an error about low memory means you need more
RAM, not hard disk space), even if you don’t know exactly how big the biggest hard drive is on the market.
Where knowing what the latest and greatest is becomes the most important is when you go to purchase
hardware. Then, you really do need to know that you can get X performance for X price so you can make a
good purchase decision. But you don’t have to be a hardware junkie—unless you want to be.
Figure 1.5
The connectors you’ll
see on the back of your
computer
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CHAPTER 1
FIVE EASY PIECES: PC HARDWARE IN A NUTSHELL
Whew! Look like a lot of stuff? Well, of course, it is a lot of stuff! If there weren’t a whole bunch of
things to learn in PC hardware, this would be a pretty short book, right? But fear not, I promise I’ll
cover it all.
Now that the basics have been covered, it seems like it’s a good time to dive into more details about
the innards of your computer, starting with the core PC components described in Chapter 2.
