meljun cortes computer organization_lecture_chapter_17

Chapter 17

Video

MELJUN CORTESMELJUN CORTES

© 2007 The McGraw-Hill Companies, Inc. All rights reserved

OverviewIn this chapter, you will learn to

Explain how video displays work

Select the proper video card

Install and configure video software

Troubleshoot basic video problems


Video Video consists of two devices—the video

card (display adapter) and the monitor

The video card consists of two distinct componentsOne takes commands from the computer and

updates its own onboard RAM

The other scans the RAM and sends data to the monitor

Monitor Video card

CRT Monitors


CRT All CRT monitors have a cathode ray tube

(CRT), which is a vacuum tube

One end of this tube is a slender cylinder that consists of three electron guns

The wide end of the CRT is the display screen


CRT When power is applied to the electron

guns, a stream of electrons is generated

This stream is subjected to a magnetic field generated by a ring of electromagnets called a yoke

The phosphor coating releases energy as visible light when struck by the electronsPhosphors continue to glow momentarily

after being struck—called persistence

CRT Refresh RatesCompTIA A+Essentials

Essentials


CRT Refresh Rates

Horizontal refresh rate (HRR)The speed at which the

electron beam moves across the screen

Vertical refresh rate (VRR)The amount of time

taken by the monitor to draw the entire screen and get the electron beam back to the start

Video data is displayed on the monitor as the electron gun sweeps the display horizontally, energizing appropriate areas on the phosphor coating.


CRT Refresh RatesVideo cards push the monitor at a given

VRR, and then the monitor determines the HRRIf the VRR is set too low, you’ll see flicker If it is set too high, you’ll have a distorted

screen image and may damage the monitor

Multisync (multiple-frequency monitor) monitors support multiple VRRs


Phosphors Phosphors and shadow

maskPhosphors are dots

inside the CRT monitor that glow red, green, or blue when an electron gun sweeps over them

Phosphors are evenly distributed across the front of the monitor One group of red, green,

and blue phosphors is called a triad


Shadow MaskShadow mask is a screen that enables the

proper electron gun to light the proper phosphor

Electron guns sweep across the phosphors as a group

The area of phosphors lit at one time by a group of guns is called a picture element, or pixel


ResolutionMonitor resolution is always shown as the

number of horizontal pixels times the number of vertical pixels

Some common resolutions are 640 x 480, 800 x 600,1024 x 768, 1280 x 1024, and 1600 x 1200

These resolutions match a 4:3 ratio called the aspect ratio


Dot Pitch Dot pitch—diagonal distance between

phosphorous dots of the same color

Range from 0.39 mm to as low as 0.18 mm

The lower the dot pitch, the more dots across the screen,

which produces a sharper, more defined image


Bandwidth Bandwidth—number of times an electron

gun can be turned on or off per secondBandwidth is measured in megahertz (MHz)VRR determined by bandwidth and resolution

Bandwidth pixels per page = Maximum VRR

For example, a 17-inch monitor with a 100MHz bandwidth and a resolution of 1024 x 768 can support a maximum VRR of 127 Hz

100,000,000 (1024 x 768) = 127 Hz


LCD MonitorsLiquid crystal displays

Thinner and lighter

Much less power

Flicker free

Don’t emit radiation

Called flat panels or flat panel displays


How LCDs Work Liquid crystals take advantage of the

property of polarization

Liquid crystals are composed of specially formulated liquidLiquid is full of long, thin crystals that always

orient themselves in the same direction

The crystals act exactly like a liquid polarized filter


Liquid Crystal MoleculesLCD monitors use liquid crystal molecules

that tend to line up togetherThese molecules take advantage of

polarizationFine grooves in a piece of glass will cause the

molecules to line up along the grooves


Twisting MoleculesUse two pieces of glass with fine grooves

oriented at a 90° angle

Molecules in the middle will try to line up to both sides—creating a nice twist


Add Polarizing FiltersNow add polarizing filters to both sides

The liquid crystal will twist the light and enable it to pass through

Adding an electrical potential will cause the crystals to try to align to the electrical fieldTo darken an area, apply a charge


Passive MatrixUses three matrices to produce color

Above the intersections of the wires, glass covers tiny red, green, & blue dots

Slow and tends to create an overlap between pixels

Slightly blurredeffect


Dual-Scan Passive MatrixRefreshes two lines at a time

Still used on some low-end LCD panels

Largely replaced with TFTThin film transistor


Thin Film Transistor (TFT) Thin film transistor (TFT) is also known as active matrix

It uses one or more tiny transistors to control each color dot

Brighter, with better contrast

Can handle a variety of colors, and has a much wider viewing area


LCD ComponentsBacklights illuminate the image

Inverters power the backlights (with AC)

LCD logic board uses DC

Cold cathode fluorescent lamp (CCFL) usedin backlights


LCD Resolution All LCD monitors have a native resolution

Display sharpest picture when set to this resolution

LCD panels cannot display more than their pixel limitation

When set to lower resolutions, image quality is severely degraded


LCD ComponentsBrightness

Determined by backlightMeasured in nits (100 to 1000 with the avg. at 300)

Response rateSimilar concept as refresh rateLower rate (6–8 ns) betterLow-end LCDs (20–25 ns) have ghosting problems

Contrast ratioDifference between lightest and darkestLow end (250:1) to high end (1000:1)


ProjectorsFront-view and rear-view

CRT projectors used first and are expensive

LCD projectors light and comparatively inexpensive

Today, almost all portable projectors are LCDs


Projector FeaturesLumens

Amount of light provided by a light sourceHigher lumens = brighter picture

ThrowSize of an image at a certain distanceRelated to aspect ratio

LampsGet very hotExpensive—typically a few hundred dollars


Common FeaturesOverview

SizeConnectionsAdjustments


Common Features—Size CRT monitors measured in inchesMonitor size (not viewable area)Viewable image size (VIS)—screen size from

diagonal corners

LCD monitors use just the VIS value

Monitor size VIS


Common Features—Connections Traditional CRT monitors use

a 15-pin, 3-row, DB-type connector and a power plug

LCDs can use DB-15 or digital video interface (DVI)DVI-D (digital)DVI-A (analog)DVI A/D or DVI-I (interchangeable)

DVI to VGA Adapter


Common Features—ConnectionsThe Random Access Memory Digital-to-Analog

Converter (RAMDAC) chip Converts digital signals into analog signals for

analog CRTs

LCD monitors use digital signals Circuitry for converting analog signals to digital

usually on board the LCD monitorsWhen using the DVI connection, not translated to

analog (RAMDAC not used)Digital from video card sent and used as digital

on LCD monitor


RAMDAC


Common Features—Adjustments

ControlsOn/off buttonBrightness/contrast buttonOnboard menu system

Two main functions of menuPhysical screen adjustmentsColor adjustments


Power Conservation About half the power required by the PC is

consumed by the CRT monitorMonitors that meet the VESA specs can reduce

power consumption by +/–75 percentDone with Display Power-Management Signaling

(DPMS)

CRT monitor consumes +/–120 wattsPower-down DPMS mode reduces to +/–25 wattsFull shutoff DPMS mode reduces to +/–15 wattsTakes about 15–30 seconds to restore display


Power Conservation LCD monitor uses less than half the

electricity as a CRT

19-inch 4:3 flat panel display uses +/– 33 watts at peak usageLess than 2 watts in DPMS modeReplacing CRTs with LCDs can have an

impact on the electric bill

Video Cards


Video Card Two major components

1. Video RAM Stores the video image

2. Video processor circuitry Takes information from video RAM and

sends it to the monitor


Video RAMText video cards display only the 256 ASCII

characters Older systems displayed on 80 chars/row and

only 24 rows—only 1920 bytes of RAM needed

Graphics video cards could turn any pixel on or off Resolution of 320 x 200 pixels required 8 KBTo add color, multiple bits added

8 bits = 256 colors 24 bits = 16.7 million colors (true color)Color depth is represented as bits (color depth of 24 bits) and

not the number of colors


Color Depth• Color depth is represented as bits

– “Color depth of 24 bits”– Not the number of colors– 24 bits commonly referred to as “true color”

Number of Colors Number of Bits2 colors 1 bit (mono)4 colors 2 bits256 colors 8 bits64,000 colors 16 bits16.7 million colors 24 bits16.7 million colors8-bit opacity

32 bits


Video ModesVGA (640 x 480)Beyond VGA

SVGA, XGA, and more

Mode Resolution Mode ResolutionQVGA 320 x 240 WSXGA 1440 x 900WVGA 800 x 480 SXGA+ 1400 x 1050SVGA 800 x 600 WSXGA+ 1680 x 1050XGA 1024 x 768 UXGA 1600 x 1200WXGA 1200 x 800 HDTV 1080 1920 x 1080HDTV 720 1280 x 720 WUXGA 1920 x 1200SXGA 1280 x 1024 WQUXGA 2560 x 1600


Motherboard ConnectionPCI slots

800 x 600 with refresh of 70 Hz at 8 bits (256 colors) requires 33.6 Mbps bandwidth

24 bits (16.7 million colors) requires 100.8 Mbps

Not enough bandwidth available on shared PCI bus

AGP (accelerated graphics port)Dedicated to video Several advantages over PCI


AGP BenefitsAGP is a single special port dedicated to video

Derived from the 66-MHz, 32-bit PCI 2.1 specificationStrobing increases signals two, four, and eight times for

each clock cycleUses its own dedicated data bus connected to NorthbridgeSupports pipelining Uses sidebanding (can send and receive at same time)Can “steal” chunks of regular system memory


PCIe (PCI Express)Developed to be replacement for PCIDesigned to replace AGP alsoIncredibly fast serial communicationsSupports many of the AGP benefits

SidebandingSystem memory access

PCIe card


Graphics ProcessorThe most important decision in buying a video

card is the graphics processor

Most video processors are made byNVIDIAATI

ATI Radeon X1950 XTX 512 MBATI ManufacturerRadeon X1950 XTX Processor & Model No.512 MB Amount of RAM


Graphics ProcessorNVIDIA and ATI release multiple models of

graphics processors each year

Most features only seen in 3-D gamesTexturesTransparencyShadowsReflectionBump mapping


Video Memory Video RAM constantly updates to reflect every

change that takes place on screen

Three bottlenecksData throughput speedAccess speedSimple capacity

Overcome bottlenecks in three waysWider bus between video RAM and video processorSpecialized super-fast RAMMore RAM


Video Memory Bus widths

64, 128, and even 256 bits wide

Most of the graphics rendering and processing is handled on the card Dedicated video processor rather than the

CPU


Video MemoryVideo RAM Technologies

Acronym Name PurposeVRAM Video RAM OriginalWRAM Windows RAM Never caught onSGRAM Synchronous

Graphics RAMSpecial SDRAM

DDR SDRAM Double Data Rate SDRAM

Used on budget graphics cards

DDR2 SDRAM DDR Version 2 Replaced with GDDR3GDDR3 SDRAM Graphics DDR V. 3 Faster DDR2GDDR4 SDRAM Graphics DDR V. 4 Upgrade of GDDR3

Installing and Configuring Video Software


Physical Installation Issues Two primary issues

1. Long cards• Some video cards are tall

and may not fit in all cases• Get a new case or new

video card

2. Proximity to nearest PCI card Video cards run very hot Leave space for ventilation Good practice is to leave the slot next to an

AGP card empty to allow better airflow


Software Two-step process

1. Load the drivers Install from CD or use built-in

driver (if you must) Built-in driver likely the oldest Check the manufacturer’s

Web site for updates

2. Check the drivers• Use the Display applet


Display Applet Found in Control Panel or right-click the desktop and

choose Properties

Making the screen pretty Themes Desktop Appearance

– Other tabs Screen Saver Settings


Display AppletScreen Saver

Power Managementfeatures

Covered in Chapter 19


Display AppletSettings tab

Allows you to configure multiple monitorsCan configure resolution and color depth


Display Applet—Advanced

Monitor tab

Can update monitor driver

Can set the screen refresh rate Change in small increments Can cause damage


Display Applet—AdvancedMany video cards have card-specific tab

Color CorrectionCan adjust screen colors

RotationPortrait or Landscape

ModesVery advanced settingsUsually not needed


Working with DriversVideo drivers work same way as other

hardware driversCan access this screen

from Device Manager or Device applet

Update driverRoll back driverUninstall driver

As a basic rule Uninstall old drivers before

installing drivers for new video card


IT TechnicianCompTIA A+Technician

3-D Graphics


3-D GraphicsImprovements driven by games

Although improvements used in other applications such as computer aided design (CAD)

First-person shooters (FPSs) such as Wolfenstein 3D and Doom started move to 3-D


Transformation and SpritesMovement of 3-D objects referred to as

transformation (CPU intensive)Intel’s SIMD and AMD’s 3DNow! expressly

designed to perform transformation

Early 3-D games used sprites Just a bitmap graphic moved

around on the screen

Each figure had a limited number of sprites or angles of view


3-D ObjectsThe second generation produced 3-D

objects thru a process called renderingComposed of a group of points or verticesVertices were connected with lines (called

edges)The edges form triangles that create

polygonsThe last step is adding a texture (or skin)


3-D Video CardsGraphics processing units needed

Screens redrawn at least 24 times per second

3-D video cards have massive amounts of RAM for textures and fast processors for transformations

Application programming interfaces (APIs) created to talk to hardware directly OpenGL ported from UNIX DirectX (Microsoft only)


DirectX and Video CardsDirectX provides direct access to hardware as

follows:

DirectDraw: for 2-D graphicsDirect3D: for 3-D graphicsDirectInput: for joysticks and game controllersDirectSound: for waveformsDirectMusic: for MIDI devicesDirectPlay: for multiplayer gamesDirectShow: for video and presentation devices


DirectX Diagnostic Tool Accessories | System Tools | System Information

Tools | DirectX Diagnostic Tool Or…Run DXDiag


Web sitesSome useful Web sites to visit before

making a hardware-buying decision

www.arstechnica.comwww.hardocp.comwww.tomshardware.com

www.sharkyextreme.com

http://www.arstechnica.com/

http://www.hardocp.com/

http://www.tomshardware.com/

http://www.sharkyextreme.com/

Troubleshooting Video


Video Card Problems Vast majority of problems are

Improper or corrupt driversIncorrect settings

Incompatible or corrupt driver symptoms640 x 480 mode16-color VGA

Your responseBoot into safe mode and remove driverUse Add/Remove programs if availableUse Device Manager


Video Card HW ProblemsHardware problems usually just

one of two Fan has gone outRAM is faulty

Faulty hardware symptomsBizarre outputMay see mouse movingDisplay is a mess


Video Card ProblemsDon’t forget the obvious

If everything is sideways, check the rotation settings

Limited colors—check the color depth

Resolution set too high“Input signal out of range”


Troubleshooting Monitors

Opening up a monitor can be deadly

Even when the power is disconnected, certain components inside a monitor retain a substantial voltage for an extended period of time. If you accidentally short

one of the components, it could actually kill you!


Troubleshooting MonitorsDangerous inside a monitor

Proper adjustment requires specialized training

Your goal is to determine if a problem is in one these three categories:Common monitor problemsExternal adjustmentsInternal adjustments


Common Monitor ProblemsControl buttons are replaceable

Check with the manufacturer

Ghosting, streaking, fuzzy vertical edges Check the cable connections and cable itself

Missing color Check cable for breaks, bent pins, and

monitor adjustments

Loss of brightness Normal with age, so use power managementInternal adjustments may be made


Common Problems—CRTsYou may be able to fix this

Big color blotches—degauss it with degauss button

It’s probably beyond fixingDim display (with brightness turned up)

Take it in to a repair shopOut of focus—adjustment near the

flyback transformerHissing or sparking sounds Bird-like chirping soundsSingle horizontal or vertical lineSingle white dot on a black screen


Troubleshooting Monitors External controls provide users with the opportunity to

fine-tune the monitor’s image

Brightness and contrast

Pincushioning

Trapezoidal adjustments

Tint and saturation of color

Monitors have a built-in circuit called a degaussing coil Eliminates magnetic build-up A fuzzy looking monitor may be fixed by degaussing it Disregard the loud “thunk” sound—it’s normal


Troubleshooting CRTsConvergence defines how closely the three

colors will combine

Misconvergence causes halosMost likely near the edges of the screenCan be set by internal adjustments

Schematics of monitor will show location of variable resistor that can be adjustedManufacturers won’t give you the schematicsLeave to a trained specialist


High-Voltage AnodeUnder the suction cup is

the actual high-voltage anode

The wire leading from the suction cup goes to the flyback transformer

There’s a big capacitor that can hold up to 25,000 volts of charge for days, weeks, months, or even years

Lifting this suction cup will almost

certainly kill you!

High-voltage anode


Do NOT attempt todischarge a monitor

unless properly trainedand equipped

Discharging a CRT


Common Problems—LCDsSymptoms

Cracked LCD monitors: not repairableLCD goes dark: lost either lamp or inverterHissing noise: inverter is about to fail

LCD repair companiesSpecialize in repairing LCD monitors

Bad pixelsNormal to have some bad pixelsDead pixel: never lights upLit pixel: stays on pure whiteStuck pixel: stays on certain color


Cleaning Monitors Anti-static monitor wipes or anti-static

cloths should be used for cleaning the monitor

Do not use window cleaners

Avoid commercial cleaning solutions on LCD screens


Beyond A+Video setting for EGA/VGA

Has no meaning today and is ignored Init Display First

Determines which monitor to boot first in a multi-monitor system

Assign IRQ for VGANot needed for low-end cardsHigh end: Try it each way

VGA Palette SnoopNot used today

Video Shadowing EnabledTypically ignored but sometimes required to be off


SLI and CrossfireSplitting the processing load between two

or more GPUsNVIDIA calls theirs Scalable Link Interface

(SLI)ATI calls theirs CrossFire

Two video cards installed and connected with a bridge card


TV and PCsTV Out connects computer to TV

Tuner cardsAllows PC to mimic some

features of Tivo

HDMI (High DefinitionMultimedia Interface)Designed to replace

DVI connections


TV and PCsPlasma

Not suited for PCsOdd native resolutions (such as 1366x768)Burn-in—tendency for a screen to ghost an image

DLPDigital light processing

SED, FEDCombines CRT strengths with LCD strengthsSurface-conduction electron emitter displayField emission display

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