A Computer with Peripheral Devices

A COMPUTER WITH PERIPHERAL DEVICES

ScannerScanner MonitorMonitorSpeakerSpeaker

External DriveExternal Drive

KeyboardKeyboard

MouseMouse

COMPARISON OF PC KEYBOARD TYPES

XT Keyboard

AT (Standard)

AT (Enhanced)

OTHER KEYBOARDS

Dvorak LayoutDvorak Layout

Ergonomic Keyboard

Ergonomic Keyboard

KEYBOARD DIN CONNECTORS

HOW A KEYBOARD WORKS

Scan code Interprets the key

New scan code

COMMON KEYBOARD PROBLEMS Keys stick. User with physical limitation is currently

unable to use the standard keyboard. No input is sent when keys are pressed. Keyboard-related messages or beep codes

given during computer boot. Wrong characters are displayed on the

screen when user inputs information. Multimedia buttons not working properly. New keyboard won’t plug into the same

port as the old keyboard.

POINTING DEVICES

MouseMouse

TrackballTrackball

TouchpadTouchpad

HOW A MECHANICAL MOUSE WORKS

Click!

Encoder wheelEncoder wheel

COMMON POINTING DEVICE PROBLEMS Mouse pointer jumps around on the

screen. Cordless mouse is in use and mouse

pointer is jumping around or not moving.

Mouse works sometimes, but not others. Mouse is not working. USB mouse is not working properly.

A CRT MONITOR

AN LCD FLAT-PANEL MONITOR

VIRTUAL REALITY GLASSES

A VIDEO PROJECTOR

A TOUCH SCREEN MONITOR

DataData

HOW COLOR CRT MONITORS WORK

Red

Blue

Green

Color dots

Electron gunsElectron guns

Magnetic yokeMagnetic yoke

Horizontal & vertical deflection coils

Horizontal & vertical deflection coils

Technology Description

Shadow mask

One way to keep the beam from hitting the wrong dot is to usea metal sheet with a tiny hole for each trio of adjacent red,green, and blue dots. This grill is a shadow mask; it keeps strayelectrons from bleeding over into other colored dots.

Aperture grill

Other monitors use very thin vertical strips of metal to block thestray electrons from hitting the wrong dots on the tube. Thesestrips form an aperture grill. Monitors using the aperture grillmay have a brighter display with a sharper image, but wiresused to stabilize the strips form very thin horizontal lines on thescreen image.

Slotted maskThis is a combination of shadow mask and aperture grilltechnologies. It uses vertical slots with horizontal masks to producea stable image that is brighter than shadow mask.

ELECTRON BEAM POSITIONING TECHNOLOGIES USED IN MONITORS

DISPLAY CHARACTERISTICS

Characteristic Description

Resolution The maximum number of pixels on a monitor.

Refresh rateThe number of times per second that the entire monitor is scanned to illuminate the pixels.

Color depth The number of bits used to store the color of a pixel.

Font A size and style of typeface.

DB 15-PIN HIGH-DENSITY VGA CONNECTOR

12345

678910

1112131415

RELATIVE SCREEN SIZESThe aspect ratio of most computer monitors is 4:3

DISPLAY PROPERTIES

MONITOR DISTORTIONS

Pincushion Barrel Trapezoid

MONITOR TEST PATTERN

POWER MANAGEMENT

A VGA CONNECTOR

A DVI-I RECEPTACLE CONNECTOR

COMMON MONITOR PROBLEMSNo image displayed on the monitor.Monitor flickers.Monitor is dark or power indicator

light is not lit.Monitor turns itself off.Screen is fine until a specific

application is started, then the screen goes blank, flickers, or acts bizarrely.

Monitor is on, but rather than displaying an image or being black, it is white.

A DOT-MATRIX PRINTER

Creates images using pins that strike an inked ribbon

Slot for font cardsSlot for font cards

Moves bail bar against or awayfrom the platten

Moves bail bar against or awayfrom the platten

Cut sheet feederCut sheet feeder

Print headPrint head

Adjust gap between print head and paperAdjust gap between print head and paper

RibbonRibbonManually advance

the ribbonManually advance

the ribbon

Select Tractor or Friction Feed

Select Tractor or Friction Feed

Adjust printer settings with these buttons

Adjust printer settings with these buttons

TRACTOR FEED

Continuous sheet paper with perforations to

create individual sheets

Continuous sheet paper with perforations to

create individual sheets

Sprockets with prongs and latches fit over

holes in the edgeof the paper

Sprockets with prongs and latches fit over

holes in the edgeof the paper

FRICTION FEED

Paper loaded incut sheet feederPaper loaded incut sheet feeder

Bail holding paper against

the platten

Bail holding paper against

the platten

Lever set for cut sheet, friction feed

Lever set for cut sheet, friction feed

HOW A DOT-MATRIX PRINTER WORKS

Print headPrint head

PaperPaper Ink ribbonInk ribbon

TractorTractor

Electrical signals cause pins to move out toward the ribbonElectrical signals cause pins to move out toward the ribbon

Electrical signals from microprocessor

Electrical signals from microprocessor

CoilsCoils PinsPins

AN INKJET PRINTER

Paper feeds straight through the same side up from cut sheet feeder at the top to the output tray at the lower front

Ink cartridgeswith integratedprint heads

Separate black and color cartridges;color cartridge contains reservoirs forcyan, magenta, and yellow

HOW AN INKJET PRINTER WORKS

Print head and reservoir

Print head and reservoir

Ink is sprayed onto the paperInk is sprayed onto the paper

PaperPaper

RollersRollersPrint head

nozzle detailPrint head

nozzle detail

Resistor creates heat that vaporizes some of

the ink from the reservoir

Resistor creates heat that vaporizes some of

the ink from the reservoir

Melted ink is forced out to spray against the paper; each droplet is about one

one-millionth of a normal drop

Melted ink is forced out to spray against the paper; each droplet is about one

one-millionth of a normal drop

A LASER PRINTER

Output trayOutput tray

IR portIR port

Laser cartridgeLaser cartridge

LocalTalk portLocalTalk port

Type B parallel portType B parallel port

Type C parallel portType C parallel port

Input traysInput trays

HOW A LASER PRINTER WORKS

Toner supplyToner supply

PaperPaper

EP drumEP drum

Corona wire charging the drum

Corona wire charging the drumLaserLaser

Fusing unit usesheat and pressure

to adhere tonerto paper

Fusing unit usesheat and pressure

to adhere tonerto paper

Corona wires charging the paper

Corona wires charging the paper

COMPARISON OF PRINTER TYPES

Printer Type Description

Dot matrixForms images using a set of pins that strike aninked ribbon.

Inkjet Forms images by spraying ink on the paper.

LaserForms images on paper by using a laser beam and anelectrophotographic drum.

Solid ink Uses ink from melted solid-ink sticks.

Dye sublimationUses a thermal process to transfer dye topaper to create images.

Thermo autochrome

Uses special paper that has cyan, magenta, and yellow layers.

Thermal wax Uses plastic films covered with colored wax.

THE WINDOWS PRINT PROCESS

ApplicationApplication

User prints document11

GDIGDI

Calls printer driver22

Print driverPrint driver

Renders job33

Client-side spooler

Client-side spooler

Returns control to application

44

Server-side spooler

Server-side spooler

Inserts job into print stream

55

Print routerPrint router

Which print server?66

THE WINDOWS PRINT PROCESS (CONT.)

Separator page processor

Separator page processor

Spools job and locates print processor

7A7ACompletes rendering7B7B

Inserts separator page

7C7C Communicates with printer7D7D Produces

output7E7E

PrinterPrinterPrint processor

Print processor

Local print provider

Local print provider

Port monitor

Port monitor

To NetWare

To WindowsRemote print provider88

COMMON PRINT PROBLEMS Nothing will print from any application. Printer doesn’t print the way the user

expects it to. User can’t access network printer. Printer prints part of a document then

prints garbage for the rest of the document.

COMMON DOT-MATRIX PRINTER PROBLEMS Horizontal lines appear in the print so

parts of characters are missing. Flecks and smudges on the paper. Poor print quality. Continuous-feed paper jams.

COMMON INKJET PRINTER PROBLEMS Poor print quality. No output; paper passes through printer

but is blank. Fuzzy output.

COMMON LASER PRINTER PROBLEMS Smeared output or output rubs off the

paper. Low-quality image. Repeating horizontal lines or white

spaces. Repeating vertical lines or white spaces.

ENVIRONMENTAL EFFECTS ON PRINTING A clean environment prolongs the life

and usability of most equipment, including printers.

Relative humidity of 50 to 60 percent is good for computer equipment.

SCANNERS

DIGITAL CAMERA

A TOUCH SCREEN INTERFACE CONNECTED VIA USB

USB connectorUSB connector

Touch sensor panel

Touch sensor panel

SPEAKERS

MICROPHONES