The Visible PC. Overview. How the PC Works. How the PC Works

Overview The Visible PC • In this chapter, you will learn how to – Describe how the PC works – Identify the essential tools of the trade and avoid e...
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The Visible PC

• In this chapter, you will learn how to – Describe how the PC works – Identify the essential tools of the trade and avoid electrostatic discharge – Identify the major internal and external components of a PC – Identify the different connectors on a typical PC system unit

How the PC Works • Computer functions thru four stages: – Input provides the computer with data • Keyboard and mouse

How the PC Works

– Processing is when the computer processes or manipulates your data – Output is seeing the result of processing your data • Monitor and printer

– Storage is how you keep your data for later use • Floppy diskette, CD-ROM disk, hard drive

• Hardware and software interact together to accomplish the four stages above

How the PC Works

Hardware vs Software


PC Tool Kit

Essential Tools of the Trade ESD Avoidance

• The basic tech tool kit consists of a Phillips-head screwdriver but most fullyfunctional tool kits contain a few other items • It’s a good idea to include: – Magnifying glass – Small flashlight

Electrostatic Discharge • Electrostatic discharge (ESD) is the passage of a static electrical charge into your PC – Static electricity will destroy sensitive parts of your PC

ESD Failures • Upset failures – No detectable physical damage – One-time failure such as when your PC just reboots itself and then seems fine – Fairly common

• Degradation failures – Component is physically damaged and fails at unpredictable times – Causes intermittent failures – Fairly common

• Catastrophic failures – Component is physically destroyed and doesn’t work anymore

Anti-static Tools • Anti-static wrist strap – Keeps you and the PC at the same electrical potential to prevent ESD

• Anti-static mats – Used to temporarily place parts taken out of your PC

Recognizing the Major Components of a PC

• Anti-static bags – Used to store electrical components from your PC

• Always unplug your PC when you work on it – don’t just turn it off




• Central Processing Unit (CPU)

• Makes

• Models

– Intel – AMD

– Also called a microprocessor – Performs calculations – Modern CPUs generate a lot of heat

– – – –

Celeron Athlon Duron Pentium

• Uses a cooling fan and/or heat sink

CPU • Clock speed is used to measure the performance

RAM • CPUs come in different packages

– Measured in megahertz (MHz)

– Land Grid Array (LGA) – Pin Grid Array (PGA) • Most common today

– Single Edge Cartridge (SEC)

• Random Access Memory (RAM) – Stores programs and data your PC is currently working on – Measured in megabytes (MB) – Each piece or module of RAM is called a stick – Packages include • Dual Inline Memory Module (DIMM) • Single Inline Memory Module (SIMM)

• Older package



• The motherboard is a thin, flat piece of circuit board – Everything connects directly or indirectly to the motherboard – Contains sockets for the CPU, RAM, power connectors, connectors for external devices like mice, printers, and keyboards – Expansion slots allow the addition of new components


Case • The case houses all of the internal components of your PC – Includes slots or holes to enable external devices to connect

Floppy Drive • The 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

Power Supply • The power supply provides electrical power to make the PC operate – Uses power from the wall outlet – Provides special connectors to the motherboard and other devices – Uses a fan to keep itself and the PC cool inside

Hard Drive • Hard Drives store programs and data not currently in use by the CPU – Capacity measured in megabytes (MB) or gigabytes (GB) – A typical PC has one hard drive but may contain up to four hard drives – Common types include • AT Attachment (ATA) • Small Computer System Interface (SCSI)

– Connects to PC via a ribbon cable – Uses a power cable from the power supply

CD-ROM Drive • CD-ROM drives enable access to CD-ROM discs – EIDE, SATA and SCSI versions – PCs may come with recordable CD-ROM drives that use CD-R discs – Newer PCs use CD-RW drives that allow rewriting to the disc – called burning – Today PCs come with digital video discs (DVDs) that store huge amounts of information

Storage Hierarchy • Primary storage – Memory

• Secondary storage – Hard drive – Floppy drive – Cd-rom, dvd-rom


DB Connectors • DataBus or DB connectors have a slight D-shape


DIN Connectors • DIN (Deutsches Institut für Normung) connectors are round and come in two sizes – DIN – Mini-DIN

• Always a female connector • Used frequently by a keyboard or mouse

RJ Connectors • Registered Jack or RJ connectors are used by module telephones (RJ-11) and network cards (RJ-45) and plug into appropriate ports

– Male DB connectors have pins – Female DB connectors have sockets – Oldest type of connector in the PC

Centronics Connectors • Centronics connectors have a D shape with one large central tab – Uses contacts instead of pins • Still called pins, though

– Uses wire rings to hold connector on – Older printers use a 36pin Centronics socket

BNC Connectors • BNC connectors are becoming obsolete – Also called coaxial or coax – Older network cards may use a BNC connector – TV cards may also use a coaxial connection


Audio Connectors • Audio connectors are used on sound cards – Used to connect speakers, microphones, and other audio devices – Mini-audio connectors are the only type used in PCs

USB Connectors • Universal Serial Bus (USB) – Used by many devices today – Devices are hotswappable • Meaning you can insert or remove the device while the PC is running

– May daisy-chain multiple USB devices together

FireWire Connectors • FireWire connectors move data at incredibly high speeds – Also known as IEEE 1394 – 6-wire/4-wire cable – Cables may be no longer than 5 meters – High speeds of 100-400 Mbps – Supports daisy-chaining – Hot-swappable

Sound Cards • Sound cards – take digital information and turns it into sound – Take sound from a microphone and turns it into digital data – Use mini-audio jacks for speakers and microphones – Use a 15-pin DB socket for a joystick or musical instrument

Common PC Devices

Video Cards • Video cards connect to monitors – Use a 15-pin female DB connector or the newer digital video interface (DVI) connector


Network Cards • PCs connect to other PCs to share information or devices using a network interface card (NIC) – Connectors include RJ45, BNC, DB

Serial Ports • Serial ports are used to add external devices to a PC – Takes a stream of serial data from the CPU and outputs it in a serial format – 9-pin or 25-pin serial ports

Modem • Modems work with your telephone to translate analog telephone signals into digital serial data or vice versa – Internal modems are expansion cards – External modems connect to a serial port – Uses two RJ-11 sockets

Keyboard • Keyboards come in many sizes and shapes – Use a keyboard port on the motherboard – DIN connector is obsolete – Mini-DIN is most common today – USB connectors are sometimes used today – Use the same kind of connector as a mouse but most PCs clearly mark the connectors

Mouse • A mouse allows you to select graphical items on a screen – Early computers did not need a mouse – Mice used to connect to the PC thru a 9-pin or 25pin serial port – Now mice connect thru a mini-DIN (or PS/2) port which is also serial – Today mice may use a USB port – Trackballs may be used instead of mice

Printer • Printers output data from the PC onto paper – Used a 25-pin parallel port for years – Today printers almost exclusively use a USB port

• One to the telephone jack on the wall • One to a telephone if you wish



Hardware Inside the Computer Case

• Joysticks are used almost exclusively to play games on the computer – Originally designed as an input device to be used much like a mouse is