Chapter 2The Visible PC

MELJUN CORTESMELJUN CORTES

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OverviewIn this chapter, you will learn to

Describe how the PC worksIdentify the essential tools of the trade and

avoid electrostatic discharge (ESD)Identify the major internal and external

components of a PCIdentify the different connectors on a typical

PC system unit

How the PC Works

`Input

Output

Processing

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How the PC WorksSoftware

Operating system (Windows, MAC OS X, Linux)

Applications (PowerPoint, Word, Outlook, Internet Explorer)

HardwarePieces you can touch (mouse, monitor,

motherboard, etc.)

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How the PC WorksComputer functions through four stages:

Input provides the computer with dataKeyboard and mouse

Processing occurs when the computer processes or manipulates your data

Output is provided as the result of processing your dataMonitor, printer, speakers

Storage is how you keep your data for later useHard drive, CD-ROM disc, floppy diskette

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How the PC WorksThe Art of the PC Technician

Hardware and software interact to accomplish the four stages

Your goal is to understand all the parts and how they interact in the various stagesBy understanding how it works, you’re better able to fix it

when it breaks

`

Broken PC PC tech Fixed PC

`

Tools of the Tradeand ESD Avoidance

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PC Tool KitThe basic tech toolkit: a Phillips-head screwdriver

Most toolkits contain a few other items It’s a good idea to include

Magnifying glassSmall flashlight

IT EssentialsCompTIA A+Essentials

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Electrostatic DischargeElectrostatic discharge (ESD) is the passage of a

static electrical charge into your PC or a PC component such as a RAM stick

Static electricity can destroy sensitive parts of a PC

ESD damage is much more prevalent in dry, cool environments

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Anti-static ToolsAnti-static wrist strap

Keeps you and the PC at the same electrical potential to prevent ESD

Anti-static matsUsed temporarily to place

parts taken out of your PCAnti-static bags

Used to store electrical components from your PC

Always unplug a PC when you work on it. Don’t just turn it off.

The Complete PC

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External ConnectionsPlug goes into a portPort/jack accepts a plugConnector can be either a port or a plug

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DIN ConnectorsDIN connectors are round and

come in two sizes:DINMini-DIN

Always a female connector

Used frequently by a keyboard or mouse

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USB ConnectorsUniversal Serial Bus

(USB)Used by many devices

todayDevices are hot-

swappable You can insert or remove the

device while the PC is powered on

USB B plugs into devicesUSB A plugs into

computers

USB B

USB A

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FireWire ConnectorsFireWire connectors move data at incredibly

high speedsAlso known as IEEE 1394Popular with video applicationsUses 6-wire connector (note the rounded edge)Hot-swappable

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DB ConnectorsDB connectors have a slight D-shape

Male DB connectors have pinsFemale DB connectors have socketsOldest type of connector in the PC

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RJ ConnectorsRegistered jack or RJ

connectors

RJ-11 used by telephone lines

RJ-45 used in network interface cards (NICs)

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Audio ConnectorsAudio connectors are

used on sound cards

Used to connect speakers, microphones, and other audio devices

Devices and Their Connectors

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Cards vs. OnboardConnectors exposed on

rear and front of PCs

Some connectors attach directly to motherboard

Some connectors attach to boards that plug into motherboard

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KeyboardKeyboards connect into dedicated mini-

DIN (usually purple) or USB

Plugs and ports usually purple

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Video CardsVideo cards connect to monitors

S-Video connector (left)Digital video interface (DVI) connector (center) 15-pin female DB connector (right)

Newer High-Definition Multimedia Interface (HDMI)

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Sound CardsSound cards

Convert digital information into soundConvert sound from a microphone into digital dataMini-audio jacks for speakers and microphonesDB-15 connector for a joystick or musical instrumentNewer Sony/Phillips Digital Interface Format (S/PDIF)

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Network CardsNetworks: groups of PCs connected together

Network interface cards (NICs) typically on motherboard (can be expansion card)

Typical connector is RJ-45

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MouseA mouse enables you to

select graphical items on a screen

Connects through mini-DIN port (usually light green) or USB port (most common)

Trackball may be used instead of mouse

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ModemModems convert analog telephone signals into

digital data and vice versa

Internal modems are expansion cards

External modems connect to a serial port

Uses two RJ-11 socketsOne to the telephone jack in the wallOne to a telephone if you wish

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Serial PortsSerial ports are used to add external devices to a PC

Accept and transmit serial data

Male DB-9 or DB-25

Largely replaced by USB

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PrinterPrinters output data from the PC onto paper

Historically used a female DB-25

Today printers almost exclusively use a USB or FireWire port

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Joystick Joysticks are used almost

exclusively to play games on the computer

Originally designed as an input device to be used like a mouse

Connector typically orange

Most joysticks now use USB

Inside the System Unit

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CaseThe case houses all of the internal components

Protects internal componentsExternal connections in front and rearProvides access to storage devices such as CDs

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CPUCentral processing

unit (CPU)

Also called a microprocessor

Performs calculations

CPUs generate a lot of heatCooling fan and/or heat

sink used to keep them cool

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CPUMakes

IntelAMD

ModelsCeleronAthlonSempronPentium

• CPUs come in different packages– Pin grid array (PGA)

• Most common today

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RAMRandom access memory (RAM)

Stores programs and data currently used by the CPU

Measured in megabytes (MB) and gigabytes (GB)

Each piece or module of RAM is called a stickDual inline memory module (DIMM) most common today

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MotherboardThe motherboard is a thin, flat

piece of circuit board

Everything connects directly or indirectly to the motherboard

Contains sockets for the CPU, RAM, power, and external devices such as mice, printers, and keyboards

Expansion slots allow the addition of new components

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Power SupplyProvides electrical power to PC

componentsUses 110VAC power from the

wall outlet

Has power connectors for the motherboard and other devices

Uses a fan to keep itself and the PC cool inside

Safety Alert High voltage capacitor holds power

after unplugged

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Floppy DriveThe floppy drive uses floppy diskettes to store data

Connects to the computer via a ribbon cable

Connects to the floppy controller on the motherboard

Uses a connector from the power supply

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Hard DriveHard drives store programs and data not currently in

use by the CPUCapacity quoted in megabytes (MB) or gigabytes (GB)A typical PC has one hard drive but may contain moreCommon types include

Parallel AT attachment (PATA) Serial AT attachment (SATA) Small computer system

interface (SCSI)

Uses a power cable from the power supply

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Optical MediaTwo groups

CD Stores about 700 MB CD-ROM (read only) CD-R, CD-RW (allows writing

to CD)

DVD Stores about 4 GB of data DVD-ROM, DVD+R, DVD-R,

DVD+RW, DVD-RW

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