scanner monitor speaker external drive keyboard mouse
TRANSCRIPT
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