Unformatted text preview: All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 C HAPTER The Visible PC 3 In this chapter, you will learn how to
• Describe how the PC works
• Identify all the connectors and devices on a typical PC system unit
• Discuss the major internal components of a PC Mastering the craft of a PC technician requires you to learn a lot of details about the
many pieces of hardware in the typical PC. Even the most basic PC contains hundreds
of discrete hardware components, each with its own set of characteristics, shapes, sizes,
colors, connections, and so on. By the end of this book, you will be able to discuss all
of these components in detail. This chapter takes you on a tour of a typical PC, starting
with an overview of how computers work, and then examining both external connectors and internal components.
Remember the children’s song that goes, “Oh, the leg bone connected to the thigh
bone…?” Well, think of the rest of the chapter in that manner, showing you what the
parts look like and giving you a rough idea about how they work and connect. In later
chapters, you’ll dissect all of these PC “leg bones” and “thigh bones” and get to the level
of detail you need to install, configure, maintain, and fix computers. Even if you are an
expert, do not skip this chapter! It introduces a large number of terms used throughout
the rest of the book. Many of these terms you will know, but some you will not, so take
some time and read it.
It is handy, although certainly not required, to have a PC that you can take the lid off
of and inspect as you progress. Almost any old PC will help—it doesn’t even need to
work. So get thee a screwdriver, grab your PC, and see if you can recognize the various
components as you read about them. 37 ch03.indd 37 11/26/09 3:19:49 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 38 Historical/Conceptual
How the PC Works
You’ve undoubtedly seen a PC in action: a nice, glossy monitor displaying a picture
that changes according to the actions of the person sitting in front of it, typing away on
a keyboard and clicking on a mouse. Sound pours out of tiny speakers that flank the
screen, and a box whirs happily beneath the table. The PC is a computer: a machine
that enables you to do work, produce documents, play games, balance your checkbook,
and look up the latest sports scores on the Internet.
Although the computer is certainly a machine, it’s also programming: the commands
that tell the computer what to do to get work done. These commands are just ones and
zeros that the computer’s hardware understands, enabling it to do amazing actions,
such as perform powerful mathematic functions, move data (also ones and zeros), realize the mouse has moved, and put pretty icons on the screen. So a computer is a
complex interaction between hardware and computer programming, created by your
Ever heard of Morse code? Morse code is nothing more than dots and dashes to
those who do not understand it, but if you send dots and dashes (in the right order)
to someone who understands Morse code, you can tell the recipient a joke. Think of
programming as Morse code for the computer (Figure 3-1). You may not understand
those ones and zeros, but your computer certainly does!
that a string of
ones and zeros
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All-In-One Chapter 3: The Visible PC 39
There’s more to the ones and zeros than just programming. All of the data on the
computer—the Web pages, your documents, your e-mail—is also stored as ones and
zeros. Programs know how to translate these ones and zeros into a form humans understand.
Programming comes in two forms. First are the applications: the programs that get
work done. Word processing programs, Web browsers, and e-mail programs are all considered applications. But applications need a main program to support them. They
need a program that enables you to start and stop applications, copy/move/delete data,
talk to the hardware, and perform lots of other jobs. This program is called the operating system (OS). Microsoft Windows is the most popular OS today, but there are other
computer operating systems, such as Apple Macintosh OS X and the popular (and free)
Linux (Figure 3-2). Computer people lump operating systems and applications into the
term software to differentiate them from the hardware of the computer.
Understanding the computer at this broad conceptual level—in terms of hardware,
OS, and programs—can help you explain things to customers, but good techs have a
much more fundamental appreciation and understanding of the complex interplay of
all of the software and the individual pieces of hardware. In short, techs need to know
the processes going on behind the scenes.
NOTE The CompTIA A+ certification exams only cover the Windows
operating system, so you won’t see much discussion of OS X or Linux in this
book. Nevertheless, a good tech should possess a basic understanding of these
two excellent operating systems. Figure 3-2 Typical OS X, Linux, and Windows interfaces ch03.indd 39 11/26/09 3:19:51 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 40
From the CompTIA A+ tech’s perspective, the computer functions through four stages: input, processing, output, and storage. Knowing which parts participate in a particular stage of the computing process enables you to troubleshoot on a fundamental and
decisive level. Input
To illustrate this four-step process, let’s walk through the steps involved in a fairly common computer task: preparing your taxes. [Insert collective groan here.] February has
rolled around and, at least in the United States, millions of people install their favorite
tax software, TurboTax from Intuit, onto their computers to help them prepare their
taxes. After starting TurboTax, your first job is to provide the computer with data: essential information, such as your name, where you live, how much you earned, and how
many dollars you gave to federal and state governments.
Various pieces of hardware enable you to input data, the most common of which are
the keyboard and mouse. Most computers won’t react when you say, “Hey you!”—at
least not anywhere outside of a Star Trek episode. Although that day will come, for
now you must use something decidedly more mechanical: a keyboard to type in your
data. The OS provides a fundamental service in this process as well. You can bang on a
keyboard all day and accomplish nothing unless the OS translates your keystrokes into
code that the rest of your computer’s hardware understands.
NOTE Some might argue that voice recognition, the ability for a computer
to understand your voice, has been around for a long time. In my opinion, it
doesn’t work well enough to replace my keyboard—yet. Processing
Next, the computer processes your data. After you place information in various appropriate “boxes” in TurboTax, the computer does the math for you. Processing takes
place inside the system unit—the box under your desk (see Figure 3-3)—and happens
almost completely at a hardware level, although that hardware functions according to
rules laid out in the OS. Thus again, you have a complex interaction between hardware
The processing portion is the magical part—you can’t see it happen. The first half of
this book demystifies this stage, because good techs understand all of the pieces of the
process. I won’t go through the specific hardware involved in the processing stage here,
because the pieces change according to the type of process. Output
Simply adding up your total tax for the year is useless unless the computer shows you
the result. That’s where the third step—output—comes into play (Figure 3-4). Once the
computer finishes processing data, it must put the information somewhere for you to ch03.indd 40 11/26/09 3:19:51 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 41
in here! inspect it. Often it places data on the monitor so you can see what you’ve just typed. It
might send the data over to the printer if you tell it, so you can print out copies of your
tax return to mail to the Internal Revenue Service (or whatever the tax man is called
where you live). A hardware device does the actual printing, but the OS controls the
printing process. Again, it’s a fundamental interaction of hardware and software. Figure 3-4
Output devices ch03.indd 41 Printer Speaker Monitor 11/26/09 3:19:52 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 42
Once you’ve sent in your tax return, you most likely do not want all that work simply
to disappear. What happens if the IRS comes back a couple of months later with a question about your return? Yikes! You need to keep permanent records and you need to
keep a copy of the tax program. The fourth stage in the computing process is storage.
A lot of devices are used in the storage process, the most visible of which are the external storage parts, such as a thumb drive or recordable CD discs (Figure 3-5).
(CD-R discs) The Art of the PC Technician
Using the four stages of the computing process—input, processing, output, and storage—
to master how the PC works and, in turn, become a great technician requires that you
understand all of the pieces of hardware and software involved and the interactions
between them that make up the various stages. You have to know what the parts do, in
other words, and how they work together. The best place to start is with a real computer.
Let’s go through the process of inspecting a typical, complete PC, including opening
up a few important pieces to see the components inside. Hopefully, you have a real
computer in front of you right now that you may dismantle a bit. No two computers
are exactly the same, so you’ll see differences between your PC and the one in this
chapter—and that’s okay. You’ll come to appreciate that all computers have the same
main parts that do the same jobs even though they differ in size, shape, and color.
By the time you reach the end of this book, you’ll have a deeper, more nuanced understanding of the interaction of hardware and software in the four-stage computing
process. Just as great artists have mastered fundamental skills of their trade before creating a masterpiece, you’ll have the fundamentals of the art of the computer technician
and be on your road to mastery. ch03.indd 42 11/26/09 3:19:53 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 43 Essentials
The Complete PC
Sometimes I hate the term “personal computer.” That term implies a single device, like
a toaster. A typical PC is more than one device, and you need all of the parts (or at least
most) to make the PC work. The most important part of the PC is the box that usually
sits under your desk: the one that all of the other parts connect to, called the system unit.
All of the processing and storage takes place in the system unit. All of the other parts
of the PC—the printer, the keyboard, the monitor—connect to the system unit and are
known collectively as peripherals. Figure 3-6 shows a typical desktop PC, with the system
unit and peripherals as separate pieces.
Most computers have a standard set of peripherals to provide input and output.
You’ll see some variation in color, bells, and whistles, but here’s the standard set.
● Monitor The big television thing that provides a visual output for the computer ● Keyboard ● Keypad for providing keyed input. Based on a typewriter Mouse Pointing device used to control a graphical pointer on the monitor for
● Speakers/headphones ● Printer Provides printed paper output Speakers provide sound output A typical PC has all of these peripherals, but no law requires a PC to have them.
Plenty of PCs may not have a printer. Some PCs don’t have speakers. Some computers don’t even have a keyboard, mouse, or monitor—but they tend to hide in unlikely
places, such as the inside of a jet fighter or next to the engine in an automobile. Other
PCs may have many more peripherals. Installing four or five printers on a single PC is
easy, if you so desire. You’ll also find hundreds of other types of peripherals, such as
Web cameras and microphones, on many PCs. You add or remove peripherals depending on what you need from the system. The only limit is the number of connections for
peripherals available on the system unit. Figure 3-6
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Every peripheral connects to the system unit through one of the many types of ports.
The back of a typical system unit (Figure 3-7) has many cables running from the system
unit to the various peripherals. You may even have a few connectors in the front. All of
these connectors and ports have their own naming conventions, and a good tech knows
all of them. It’s not acceptable to go around saying such things as “That’s a printer port”
or “That’s a little-type keyboard connector.” You need to be comfortable with the more
commonly used naming conventions so you can say “That’s a female DB-25” or “That’s
a USB connector.” Figure 3-7
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All-In-One Chapter 3: The Visible PC 45
Plugs, Ports, Jacks, and Connectors
Although PCs use close to 50 different types of connections, almost all fit into one of six
major types: DIN, USB, FireWire, DB, RJ, and audio. Read the next paragraph to get your
terminology straight and then you can jump into the various connectors with gusto.
No one seems to use the terms plug, port, jack, or connector correctly, so let’s get this
right from the start. To connect one device to another, you need a cable containing the
wires that make the connection. On each device, as well as on each end of the connecting cable, you need standardized parts to make that connection. Because these are
usually electrical connections, one part needs to fit inside another to make a snug, safe
A plug is a part with some type of projection that goes into a port. A port is a part that
has some type of matching hole or slot that accepts the plug. You never put a port into
a plug; it’s always the other way around. The term jack is used as an alternative to port,
so you may also put a plug into a jack. The term connector describes either a port or a
plug. As you progress though this chapter and see the various plugs and ports, this will
become clearer (Figure 3-8).
Plug, port, and
Port Plug Mini-DIN Connectors
Most PCs sport the European-designed mini-DIN connectors. The original DIN connector was replaced by mini-DIN a long time ago, so you’ll only see mini-DIN connectors
on your PC (see Figure 3-9 bottom). Older-style keyboards and mice plugged into DIN
ports (Figure 3-9 top). USB Connectors
Universal serial bus (USB) provides the most common general-purpose connection for
PCs. You’ll find USB versions of many devices, such as mice, keyboards, scanners, cameras, and printers. USB connections come in three sizes: A, B, and mini-B. The USB
A connector’s distinctive rectangular shape makes it easily recognizable (Figure 3-10). ch03.indd 45 11/26/09 3:19:54 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 46
DIN (top) and
mini-DIN (bottom) connectors Figure 3-10
USB A connector
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All-In-One Chapter 3: The Visible PC 47
You never see a USB B connector on your computer. USB B connecters are for the
other end of the USB cable, where it attaches to the USB device (Figure 3-11).
USB B connector NOTE You’ll sometimes hear USB ports and plugs described as upstream or
downstream, terms that create rather amusing conversation and confusion. It’s
all about whether you refer to the plug or the port, so here’s the scoop. The
USB A plugs go upstream to USB A ports on the host or hub. USB A ports
provide downstream output from the host or hub. So the plug is upstream and the port is
Just to add more fun to the mix, USB B plugs go downstream to devices. USB B ports
provide upstream output from the device to the host or hub. My advice? Stick with A or B
and nobody will get confused.
The USB B connector’s relatively large size makes it less than optimal for small devices
such as cameras, so the USB folks also make the smaller mini-B–style connector shown
in Figure 3-12. Figure 3-12
connector ch03.indd 47 11/26/09 3:19:56 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 48
USB has a number of features that make it particularly popular on PCs. First, USB devices are hot-swappable, which means you can insert or remove them without restarting
your PC. Almost every other type of connector requires you to turn the system off, insert
or remove the connector, and then turn the system back on. Hot-swapping completely
eliminates this process.
Second, many USB devices get their electrical power through the USB connection, so
they don’t need batteries or a plug for an electrical outlet. You can even recharge some
devices, such as cellular phones, by plugging them into a USB port (Figure 3-13).
charging via a
USB connection FireWire Connectors
FireWire, also known as IEEE 1394, moves data at incredibly high speeds, making it the
perfect connection for highly specialized applications such as streaming video from a
digital video camera onto a hard drive. FireWire consists of a special 6-wire connector,
as shown in Figure 3-14 or a 9-wire connector for devices that need more speed and
power. A smaller, 4-pin version is usually seen on peripherals. Like USB, FireWire devices are hot-swappable. DB Connectors
Over the years, DB connectors have been used for almost any type of peripheral you can
think of, with the exception of keyboards. They have a slight D shape, which allows
only one proper way to insert a plug into the socket and makes it easier to remember
what they’re called. Technically, they’re known as D-sub or D-subminiature connectors,
but most techs call them DBs. ch03.indd 48 11/26/09 3:19:57 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 49
port Each male DB plug has a group of small pins that connect to DB ports. Female DB
plugs connect to male DB ports on the system unit. DB connectors in the PC world can
have from 9 to 37 pins or sockets, although you rarely see a DB connector with more
than 25 pins or sockets. Figure 3-15 shows an example. DB-type connectors are some
of the oldest and most common connectors used in the back of PCs.
and port ch03.indd 49 11/26/09 3:19:57 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 50
NOTE Each size D-sub connector—called the shell size—has a specific name
in the D-sub manufacturing world. A two-row, 9-pin connector, for example, is
officially a DE-9 connector rather than a DB-9. The E refers to the 9-pin shell
size. Why all of the DA, DB, DC, DD, and DE connectors became DB-x in the
world of personal computers is a mystery, but most techs simply call them DB connectors.
It wasn’t that long ago that a typical PC used at least three or more different DB connectors. Over the past few years, the PC world has moved away from DB connectors.
A typical modern system has only one or two, usually for video. RJ Connectors
You have more than likely seen an RJ connector, whether or not you knew it by that name.
The little plastic plug used to connect your telephone cord to the jack (techs don’t use
the word “port” to describe RJ connectors) is a classic example of an RJ plug. Modern
PCs use only two types of RJ jacks: the RJ-11 and the RJ-45. The phone jack is an RJ-11. It
is used almost exclusively for modems. The slightly wider RJ-45 jack is used for your network connection. Figure 3-16 shows an RJ-11 jack (top) and an RJ-45 jack (bottom).
RJ-11 (top) and
RJ-45 (bottom) Audio Connectors
Speakers and microphones connect to audio jacks on the system unit. The most common type of sound connector in popular use is the 1/8-inch connector, also called a
mini-audio connector. These small connectors have been around for years; they’re just
like the plug you use to insert headphones into a radio, music player, or similar device
(Figure 3-17). Traditionally, you’d find the audio jacks on the back of the PC, but many
newer models sport front audio connections as well.
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All-In-One Chapter 3: The Visible PC 51
NOTE Keep in mind that the variety of connectors is virtually endless. The
preceding types of connectors cover the vast majority, but many others
exist in the PC world. No law or standard requires device makers to use a
particular connector, especially if they have no interest in making that device
interchangeable with similar devices from other manufacturers. Devices and Their Connectors
Now that you have a sense of the connectors, let’s turn to the devices common to almost every PC to learn which connectors go with which device.
NOTE Almost all connectors are now color-coordinated to help users plug
the right device into the right port. These color codes are not required, and
not all PCs and devices use them. Cards Versus Onboard
All of the connectors on the back of the PC are just that: connectors. Behind those connectors are the actual devices that support whatever peripherals plug into those connectors. These devices might be built into the computer, such as a keyboard port. Others
might be add-on expansion cards that a tech installed into the PC.
Most PCs have special expansion slots inside the system unit that enable you to add
more devices on expansion cards. Figure 3-18 shows a typical card. If you want some
new device and your system unit doesn’t have that device built into the PC, you just go
to the store, buy a card version of that device, and snap it in. Later chapters of the book
go into great detail on how to do this, but for now just appreciate that a device might
be built in or it might come on a card.
Be careful handling cards. Touch the metal plate with the 90-degree bend and try to
avoid touching any of the electronics. As mentioned in Chapter 2, “Operational Procedures,” always put cards into an anti-static bag when moving them to prevent ESD. Figure 3-18
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Today’s keyboards come in many shapes and sizes, but they always connect to your
computer by either a mini-DIN port or a USB port. Many keyboards ship with an adapter
so you can use either port. Most keyboard plugs and mini-DIN keyboard ports are colored
purple (see Figure 3-19).
and port Monitor
A monitor connects to the video connector on the system unit. You’ll usually see one
of two types of video connectors: the older 15-pin female DB Video Electronics Standards
Association (VESA) connector or the unique, digital video interface (DVI) connector. VESA
connectors are colored blue, whereas DVI connectors are white. Many video cards have
both types of connectors (see Figure 3-20) or two VESA or two DVI connectors. Video
cards with two connectors support two monitors, a very cool thing to do! Figure 3-20 Video card with (from left to right) S-Video, DVI, and VESA ports The newest video connector is called Hi-Definition Multimedia Interface (HDMI),
shown in Figure 3-21. HDMI is still very new to the video scene and brings a number
of enhancements, such as the ability to carry both video and sound on the same cable.
Primarily designed for home theater, computers with HDMI connectors grow more
common every year. ch03.indd 52 11/26/09 3:20:00 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 53
HDMI connector Sound
The sound device in a computer performs two functions. First, it takes digital information and turns it into sound, outputting the sound through speakers. Second, it takes
sound that is input through a microphone or some other audio source and turns it into
To play and record sounds, your sound device needs to connect to a set of speakers
and a microphone or more. All PCs have at least two miniature audio jacks: one for
a microphone and another for stereo speakers. Better cards provide extra miniature
audio jacks for surround sound. Figure 3-22 is a typical onboard soundcard showing
six different 1/8-inch jacks. Four of these are for speakers and two are for input (such
as microphones). The color scheme for sound connections is complex, but for now
remember one color—green. That’s the one you need to connect a standard pair of
An older sound card may still provide a female 15-pin DB port that enables you to
attach an electronic musical instrument interface or add a joystick to your PC (see Figure 3-23). These multi-function joystick/MIDI ports are rare today.
Adding more and more audio jacks to sound cards made the back of a typical sound
card a busy place. In an effort to consolidate the various sound signals, the industry
invented the Sony/Philips Digital Interface Format (S/PDIF) connection. S/PDIF comes in
coaxial and optical versions. Figure 3-24 shows a motherboard with both (the coaxial
connection is on the left). One S/PDIF connection replaces all of the mini-audio connections, assuming your surround speaker system also comes with an S/PDIF connection. ch03.indd 53 11/26/09 3:20:00 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 54
Typical bank of
jacks Figure 3-23
MIDI port Network
Networks are groups of connected PCs that share information. The PCs most commonly
connect via some type of cabling that usually looks like an extra-thick phone cable.
A modern PC uses an RJ-45 connection to connect to the network. Figure 3-25 shows
a typical RJ-45 network connector. Network connectors do not have a standard color. ch03.indd 54 11/26/09 3:20:01 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 55
connection S/PDIF Figure 3-25
connection NOTE Modern PCs have built-in network connections, but this is a fairly
recent development. For many years, network devices only came on an
expansion card, called a network interface card (NIC). The term is so common
that even built-in network connections—which most certainly are not
cards—are still called NICs. Mouse
Most folks are pretty comfortable with the function of a mouse—it enables you to select
graphical items on a graphical screen. A PC mouse has at least two buttons (as opposed
to the famous one-button mouse that came with Apple Macintosh computers until
recently), while a better mouse provides a scroll wheel and extra buttons. A mouse uses
either a USB port or a dedicated, light-green mini-DIN connector (see Figure 3-26). ch03.indd 55 11/26/09 3:20:02 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 56
Mouse with miniDIN connection A variation of the mouse is a trackball. A trackball does the same job as a mouse, but
instead of pushing it around like a mouse, the trackball stays in one place as you roll a
ball with your fingers or thumb (Figure 3-27). Figure 3-27
The old modem enables you to connect your PC to a telephone. Modems are another
easily identifiable device in PCs as they have one or two RJ-11 jacks. One jack is to connect the modem to the telephone jack on the wall. If the modem has a second RJ-11
jack, it is for an optional telephone so you can use the phone line when the modem is
not in use (see Figure 3-28).
NOTE External modems traditionally connected to a male 9-pin or 25-pin
D-subminiature port on the system unit called a serial port (shown below in
Figure. 3-28). Although just about every external modem today connects to
USB, a few computers still come with a serial port for legacy devices. ch03.indd 56 11/26/09 3:20:03 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 57
Internal modem Serial ports are one of the few connectors on modern systems that were also used in
the first PCs more than 20 years ago. Serial port Printer
For many years, printers only used a special connector called a parallel port. Parallel ports
use a 25-pin female DB connector that’s usually colored fuchsia (see Figure 3-29).
After almost 20 years of domination by parallel ports, most printers now come with
USB ports, FireWire, Ethernet, and Wi-Fi 802.11 b/g/n connectivity options. Parallel
ports are quickly fading away from the backs of most computers. Figure 3-29
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Joysticks weren’t supposed to be used just for games (see Figure 3-30). When the folks
at IBM added the 2-row, 15-pin female DB joystick connector to PCs, they envisioned
joysticks as hard-working input devices, just as the mouse is today. Except in the most
rare circumstances, however, the only thing a joystick does today is enable you to turn
your PC into a rather expensive game machine. But is there a more gratifying feeling
than easing that joystick over, pressing the Fire button, and watching an enemy fighter
jet get blasted by a well-placed Sidewinder missile? I think not. Traditional joystick connecters are colored orange, but most joysticks today connect to USB ports.
More and more PCs are showing up with eSATA ports like the one shown in Figure 3-31.
The eSATA is a special connector for external hard drives and optical drives. Plenty More!
Keep in mind that there are lots more devices and connectors out there. This section
includes only the most common and the ones you’re most likely to see. As you progress
through this book, you’ll see some less common connecters and where they are used. ch03.indd 58 11/26/09 3:20:04 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 59
eSATA jack Inside the System Unit
Now that you’ve seen the devices that connect to the PC, it’s time to open up the system
unit to inspect the major internal components of a typical PC. A single PC is composed
of thousands of discrete components. Although no one can name every tiny bit of
electronics in a PC, a good technician should be able to name the major internal components that make up the typical PC. Let’s open and inspect a system unit to see these
components and gain at least a concept of what they do. In later chapters, you’ll see all
of these components in much more detail. Case
The system unit’s case is both the internal framework of the PC and the external skin
that protects the internal components from the environment. Cases come in an amazing variety of styles, sizes, and colors. Figure 3-32 shows the front and back of a typical
PC case. The front of the case holds the buttons for turning the system on and off, lights
to tell you the status of the system, and doors for accessing removable media drives
such as floppy, CD-ROM, and DVD drives. This system also provides USB, FireWire,
and audio connections in the front for easy access if you want to use a device that needs
The back of the case holds the vast majority of the system unit connections. You will
also notice the power supply—almost always at the top of the case—distinguished by
its cooling fan and power plug. Note that one area of the back, the I/O area, holds all
of the onboard connections (see Figure 3-33), while another area in the back contains
slots for cards. Similarly, the case uses slots to enable access to the external connectors
on cards installed in the system unit.
NOTE You’ll hear the PC case called the enclosure, especially at the more
expensive end of the spectrum. Case, enclosure, and system unit are
interchangeable terms. ch03.indd 59 11/26/09 3:20:05 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 60
back Opening a case is always…interesting. There’s no standard way to open a case, and
I’m convinced that the folks making system units enjoy some sick humor inventing
new and complex ways to open them. In general, you detach the sides of a case by removing a few screws in the back of the system unit, as shown in Figure 3-34. Use common sense and you won’t have too many problems. Just don’t lose track of your screws
or where each one was inserted!
Once you’ve opened the case, take a look inside. You’ll see metal framework, all
kinds of cables, and a number of devices. As you inspect the devices, you may gently
push cables to the side to get a better view. Don’t forget to wear an anti-static wrist strap
(attaching it to any handy metal part of the case) or touch the metal case occasionally
to prevent ESD. Figure 3-33
Onboard devices ch03.indd 60 11/26/09 3:20:06 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 61
Opening a system
The central processing unit (CPU), also called the microprocessor, performs all of the calculations that take place inside a PC. CPUs come in a variety of shapes and sizes, as
shown in Figure 3-35.
Modern CPUs generate a lot of heat and thus require a cooling fan and heat sink
assembly to avoid overheating (see Figure 3-36). A heat sink is a big slab of copper or
aluminum that helps draw heat away from the processor. The fan then blows the heat
out into the case. You can usually remove this cooling device if you need to replace it,
although some CPU manufacturers have sold CPUs with a fan permanently attached.
CPUs have a make and model, just like automobiles do. When talking about a
particular car, for example, most people speak in terms of a Ford Taurus or a Toyota
Camry. When they talk about CPUs, people say Intel Core i7 or AMD Phenom. Over
the years, there have been only a few major CPU manufacturers, just as there are only
a few major auto manufacturers. The two most common makes of CPUs used in PCs
are AMD and Intel. ch03.indd 61 11/26/09 3:20:07 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 62
still in protective
packaging Figure 3-36
CPU with fan ch03.indd 62 11/26/09 3:20:08 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 63
Although only a few manufacturers of CPUs have existed, those manufacturers have
made hundreds of models of CPUs. Some of the more common models made over the
past few years have names such as Core 2, Core i7, Celeron, Athlon, and Phenom.
Finally, CPUs come in a variety of packages. The package defines how the CPU looks
physically and how it connects to the computer. Intel CPUs currently use a package type
called land grid array (LGA), and AMD likes pin grid array (PGA). Every CPU package
type has a number of versions and each type is designed to fit into a particular connection called a socket. Sockets have such names as Socket AM3 or Socket B. Figure 3-37
shows a CPU with its matching socket.
matching socket Chapter 5, “Microprocessors,” goes into great detail on CPUs, but for now remember
that every CPU has a make, a model, and a package type. RAM
Random access memory (RAM) stores programs and data currently being used by the
CPU. The maximum amount of programs and data that a piece of RAM can store is
measured in units called bytes. Modern PCs have many millions, even billions, of bytes
of RAM, so RAM is measured in units called megabytes (MB) or gigabytes (GB). An average PC will have from 1 to 4 GB of RAM, although PCs may have more or less RAM.
Each piece of RAM is called a stick. One common type of stick found in today’s PC is
called a dual inline memory module (DIMM). Figure 3-38 shows two examples of DIMMs
used in PCs. ch03.indd 63 11/26/09 3:20:08 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 64
Two DIMMs Your PC takes only one type of DIMM, and you must know the type so you can add
or replace RAM when needed. Chapter 6, “RAM,” covers everything you need to know
to work comfortably with RAM.
CAUTION Some parts of your PC are much more sensitive to ESD than
others.Your CPU and RAM are very sensitive to ESD. If you touch the metal
parts of your CPU or RAM and you have even the tiniest amount of charge,
you can destroy them. Motherboard
You can compare a motherboard to the chassis of an automobile. In a car, everything
connects to the chassis either directly or indirectly. In a PC, everything connects to the
motherboard either directly or indirectly. A motherboard is a thin, flat piece of circuit
board, usually green or gold, and often slightly larger than a typical piece of notebook
paper (see Figure 3-39). Figure 3-39
motherboard ch03.indd 64 11/26/09 3:20:10 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 65
A motherboard contains a number of special sockets that accept various PC components. The CPU and RAM, for example, plug directly into the motherboard. Other
devices, such as floppy drives, hard drives, CD and DVD drives, connect to the motherboard sockets through short cables. Motherboards also provide onboard connectors for
external devices such as mice, printers, joysticks, and keyboards.
All motherboards use multipurpose expansion slots in which you can add adapter cards.
Different types of expansion slots exist for different types of cards (see Figure 3-40).
Placing a card
into an expansion
slot Power Supply
The power supply, as its name implies, provides the necessary electrical power to make
the PC operate. The power supply takes standard electrical power and converts it into
power your PC can use. Most power supplies are about the size of a shoebox cut in half
and are usually a gray or metallic color (see Figure 3-41). Figure 3-41
Power supply ch03.indd 65 11/26/09 3:20:11 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 66
A number of connectors lead out of the power supply. Every power supply provides
special connectors to power the motherboard and a number of other general-use connectors that provide power to any device that needs electricity. Check out Chapter 10,
“Power Supplies,” for more information. Floppy Drive
The floppy drive enables you to access removable floppy disks (diskettes). The floppy
drive used in PCs today is a 3.5-inch floppy drive. Floppy drives only store a tiny amount
of data and have all but disappeared from PCs.
The floppy drive’s data connection to the computer is via a ribbon cable, which in
turn connects to the motherboard. The connection to the motherboard is known as the
floppy drive controller (Figure 3-42).
motherboard Hard Drive
A hard drive stores programs and data that are not currently being used by the CPU.
Although RAM storage is measured in megabytes and gigabytes, a PC’s hard drive stores
much more data than a typical PC’s RAM—hundreds of gigabytes to terabytes. A terabyte
is 1000 gigabytes.
An average PC has one hard drive, although most PCs accept more. Special PCs that
need to store large amounts of data, such as a large corporation’s main file-storage computer, can contain many hard drives—8 to 16 drives in some cases.
The two most common types of hard drives seen in today’s PCs are the older Parallel
Advanced Technology Attachment (PATA) and the more modern Serial Advanced Technology Attachment (SATA). PATA drives use a ribbon cable very similar to the one used by
floppy drives, whereas SATA drives use a very narrow cable. Figure 3-43 shows a SATA
drive (left) next to a PATA drive (right). Most motherboards come with connections for
both types of drives.
NOTE A very few PCs use small computer system interface (SCSI) drives. SCSI
drives are generally faster and more expensive, so they usually show up only in
high-end PCs such as network servers or graphics workstations. ch03.indd 66 11/26/09 3:20:11 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 67
SATA and PATA
data connectors Optical media drives use the same PATA or SATA connections used with hard drives.
Figure 3-44 shows a DVD drive sharing a single ribbon cable with a PATA hard drive—a
common sight inside a PC.
Hard drive and
DVD drive Optical Media Drives
Optical media drives enable a computer to read one or more types of optical media discs,
such as CD, DVD, or Blu-ray Disc (Figure 3-45). CDs store around 700 MB and come in
three varieties: CD-ROM (read only memory: you can’t change the data on them), CD-R
(recordable: you can change the data once), and CD-RW (rewriteable: you can change the
data on them over and over). DVDs store much more data—the smallest capacity DVDs
store around 4 GB, enough for a Hollywood movie—and come in even more varieties:
DVD-ROM, DVD+R, DVD-R, DVD+RW, and DVD-RW, just to name the more famous
ones. Blu-ray Discs are popular for high-definition movies, but there are also Blu-ray
Discs for storing data with capacities starting at 25 GB. ch03.indd 67 11/26/09 3:20:12 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 68
Assorted opticalmedia discs All of these optical-media discs require an optical-media drive that knows how to
read them. If you want to do anything with a CD-RW disc, for example, you need a
CD-RW drive. If you want to use a DVD+R disc, you need a DVD+R drive. Luckily,
most optical-media drives support many different types of discs, and some support
every common type of optical media available. Figure 3-46 shows typical optical-media
drives. Note that some of them advertise what types of media they use. Others give no
NOTE Chapter 13, “Removable Media,” goes into great detail on the assorted
discs and drive types. Figure 3-46
drives ch03.indd 68 11/26/09 3:20:13 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 69
Know Your Parts
The goal of this chapter was to get you to appreciate the names and functions of the
various parts of the PC: peripherals, connectors, and components. By starting with the
Big Picture view, you may now begin breaking down the individual components on
a chapter-by-chapter basis and truly understand at great depth how each component
works and how it interconnects with the PC system as a whole. Chapter Review
1. What do you call the commands that tell the computer what to do?
B. Morse code
2. Which of the following is a proper name for a stick of RAM?
3. Where do you connect an anti-static wrist strap? (Select the best answer.)
A. To an anti-static plate on the computer
B. To an electrical outlet
C. To a handy metal part of the case
D. To a non-static wrist strap
4. What sort of connector does a typical network card have?
5. Modern keyboards connect to which of the following ports? (Select all that
B. FireWire ch03.indd 69 11/26/09 3:20:13 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3 CompTIA A+Certification All-in-One Exam Guide 70
6. Which end of the USB cable plugs into the PC?
7. A printer usually plugs into which of the following ports? (Select all that apply.)
8. What do you plug into a three-row, 15-pin port?
9. What connector was designed to connect your PC to a high-end television set?
10. What connector was designed to connect your PC to a high-end audio system?
D. S/PDIF Review Answers
1. C. The commands that tell the computer what to do are called, collectively,
2. B. Modern computers use DIMMs for RAM. ch03.indd 70 11/26/09 3:20:14 PM All-In-One / CompTIA A+ All-in-One Exam Guide / Meyers & Jernigan / 170133-8 / Chapter 3
All-In-One Chapter 3: The Visible PC 71
3. C. Connect an anti-static wrist strap to any handy metal part of the computer.
The metal plate, by the way, is the section on the strap where you connect the
cable from the PC.
4. D. A typical network card sports an RJ-45 port.
5. C, D. Modern keyboards connect to either mini-DIN or USB ports.
6. A. Plug the A connector into the PC.
7. B, D. A printer usually plugs into either DB-25 or USB. (Although some can use
FireWire, it’s not as common.)
8. C. You plug a monitor into a three-row, 15-pin port.
9. B. HDMI was designed to connect your PC to a high-end television set.
10. D. S/PDIF was designed to connect your PC to a high-end audio system. ch03.indd 71 11/26/09 3:20:14 PM ...
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This note was uploaded on 04/27/2010 for the course COMPTIA 1201 taught by Professor N/a during the Spring '10 term at Galveston College.
- Spring '10