Video

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

VideoChapter 1: Part 12


Overview

• In 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 components– One 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 electrons– Phosphors continue to glow momentarily after

being struck—called persistence


CRT Refresh Rates

CompTIA 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 Rates

• Video cards push the monitor at a given VRR, and then the monitor determines the HRR

– If 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 mask

– Phosphors 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 Mask

• Shadow 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


Resolution

• Monitor 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 second

– Bandwidth 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 Monitors

• Liquid 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 liquid– Liquid 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 Molecules

• LCD monitors use liquid crystal molecules that tend to line up together– These molecules take advantage of polarization– Fine grooves in a piece of glass will cause the

molecules to line up along the grooves


Twisting Molecules

• Use 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 Filters

• Now 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 field• To darken an area, apply a charge


Passive Matrix

• Uses 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 Matrix

• Refreshes two lines at a time

• Still used on some low-end LCD panels

• Largely replaced with TFT– Thin 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


• Backlights illuminate the image– Inverters power the backlights (with AC)

• LCD logic board uses DC

• Cold cathode fluorescent lamp (CCFL) usedin backlights

LCD Components


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 Components

• Brightness– Determined by backlight– Measured in nits (100 to 1000 with the avg. at 300)

• Response rate– Similar concept as refresh rate– Lower rate (6–8 ns) better– Low-end LCDs (20–25 ns) have ghosting problems

• Contrast ratio– Difference between lightest and darkest– Low end (250:1) to high end (1000:1)


Projectors

• Front-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 Features

• Lumens– Amount of light provided by a light source– Higher lumens = brighter picture

• Throw– Size of an image at a certain distance– Related to aspect ratio

• Lamps– Get very hot– Expensive—typically a few hundred dollars


Common Features

• Overview– Size– Connections– Adjustments


Common Features—Size

• CRT monitors measured in inches

• Monitor 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—Connections

• The 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 monitors– When 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

• Controls– On/off button– Brightness/contrast button– Onboard menu system

• Two main functions of menu– Physical screen adjustments– Color adjustments


Power Conservation

• About half the power required by the PC is consumed by the CRT monitor– Monitors that meet the VESA specs can reduce

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

(DPMS)

• CRT monitor consumes +/–120 watts– Power-down DPMS mode reduces to +/–25 watts– Full shutoff DPMS mode reduces to +/–15 watts– Takes 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 usage– Less than 2 watts in DPMS mode– Replacing 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 RAM

• Text 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 KB– To 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 bits

256 colors 8 bits64,000 colors 16 bits16.7 million colors 24 bits

16.7 million colors8-bit opacity

32 bits


Video Modes

• VGA (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 Connection

• PCI 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 Benefits

• AGP is a single special port dedicated to video– Derived from the 66-MHz, 32-bit PCI 2.1 specification– Strobing increases signals two, four, and eight times for

each clock cycle– Uses its own dedicated data bus connected to

Northbridge– Supports 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 PCI• Designed to replace AGP also• Incredibly fast serial communications• Supports many of the AGP benefits

– Sidebanding– System memory access

PCIe card


• The most important decision in buying a video card is the graphics processor

• Most video processors are made by– NVIDIA– ATI

• ATI Radeon X1950 XTX 512 MB– ATI Manufacturer– Radeon X1950 XTX Processor & Model No.– 512 MB Amount of RAM

Graphics Processor


Graphics Processor

• NVIDIA and ATI release multiple models of graphics processors each year

• Most features only seen in 3-D games– Textures– Transparency– Shadows– Reflection– Bump mapping


Video Memory

• Video RAM constantly updates to reflect every change that takes place on screen

• Three bottlenecks– Data throughput speed– Access speed– Simple capacity

• Overcome bottlenecks in three ways– Wider bus between video RAM and video processor– Specialized super-fast RAM– More 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 Memory

• Video 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 Applet

• Screen Saver

– Power Managementfeatures

– Covered in Chapter 19


Display Applet

• Settings tab– Allows you to configure multiple monitors– Can 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—Advanced

• Many video cards have card-specific tab

– Color Correction• Can adjust screen colors

– Rotation• Portrait or Landscape

– Modes• Very advanced settings• Usually not needed


Working with Drivers

• Video drivers work same way as other hardware drivers– Can access this screen

from Device Manager or Device applet

– Update driver– Roll back driver– Uninstall driver

– As a basic rule• Uninstall old drivers before

installing drivers for new video card


IT Technician

CompTIA A+Technician

3-D Graphics


3-D Graphics

• Improvements 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 Sprites

• Movement 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 Objects

• The second generation produced 3-D objects thru a process called rendering

– Composed of a group of points or vertices– Vertices were connected with lines (called edges)– The edges form triangles that create polygons– The last step is adding a texture (or skin)


3-D Video Cards

• Graphics 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 Cards

• DirectX provides direct access to hardware as follows:

– DirectDraw: for 2-D graphics– Direct3D: for 3-D graphics– DirectInput: for joysticks and game controllers– DirectSound: for waveforms– DirectMusic: for MIDI devices– DirectPlay: for multiplayer games– DirectShow: for video and presentation devices


DirectX Diagnostic Tool

• Accessories | System Tools | System Information– Tools | DirectX Diagnostic Tool

• Or…Run DXDiag


Web sites

• Some useful Web sites to visit before making a hardware-buying decision

– www.arstechnica.com– www.hardocp.com– www.tomshardware.com– www.sharkyextreme.com


Troubleshooting Video


Video Card Problems

• Vast majority of problems are– Improper or corrupt drivers– Incorrect settings

• Incompatible or corrupt driver symptoms– 640 x 480 mode– 16-color VGA

• Your response– Boot into safe mode and remove driver– Use Add/Remove programs if available– Use Device Manager


Video Card HW Problems

• Hardware problems usually just one of two – Fan has gone out– RAM is faulty

• Faulty hardware symptoms– Bizarre output– May see mouse moving– Display is a mess


Video Card Problems

• Don’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!

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!



• Dangerous inside a monitor

• Proper adjustment requires specialized training

• Your goal is to determine if a problem is in one these three categories:– Common monitor problems– External adjustments– Internal adjustments


Common Monitor Problems

• Control 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 management– Internal adjustments may be made


Common Problems—CRTs

• You may be able to fix this– Big color blotches—degauss it with degauss button

• It’s probably beyond fixing– Dim display (with brightness turned up)

• Take it in to a repair shop– Out of focus—adjustment near the

flyback transformer– Hissing or sparking sounds – Bird-like chirping sounds– Single horizontal or vertical line– Single white dot on a black screen



• 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 CRTs

• Convergence defines how closely the three colors will combine

• Misconvergence causes halos– Most likely near the edges of the screen– Can be set by internal adjustments

– Schematics of monitor will show location of variable resistor that can be adjusted

• Manufacturers won’t give you the schematics• Leave to a trained specialist


High-Voltage Anode

• Under 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

Do NOT attempt todischarge a monitor

unless properly trainedand equipped

Discharging a CRT


Common Problems—LCDs

• Symptoms– Cracked LCD monitors: not repairable– LCD goes dark: lost either lamp or inverter– Hissing noise: inverter is about to fail

• LCD repair companies– Specialize in repairing LCD monitors

• Bad pixels– Normal to have some bad pixels– Dead pixel: never lights up– Lit pixel: stays on pure white– Stuck 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 VGA– Not needed for low-end cards– High end: Try it each way

• VGA Palette Snoop– Not used today

• Video Shadowing Enabled– Typically ignored but sometimes required to be off


SLI and Crossfire

• Splitting the processing load between two or more GPUs– NVIDIA calls theirs Scalable Link Interface (SLI)– ATI calls theirs CrossFire

• Two video cards installed and connected with a bridge card


TV and PCs

• TV Out connects computer to TV

• Tuner cards– Allows PC to mimic some

features of Tivo

• HDMI (High DefinitionMultimedia Interface)– Designed to replace

DVI connections


• Plasma– Not suited for PCs

• Odd native resolutions (such as 1366x768)• Burn-in—tendency for a screen to ghost an image

• DLP– Digital light processing

• SED, FED– Combines CRT strengths with LCD strengths– Surface-conduction electron emitter display– Field emission display

TV and PCs


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