MELJUN CORTES Computer Organization Lecture Chapter17

8/13/2019 MELJUN CORTES Computer Organization Lecture Chapter17

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Chapter 17

Video

MELJUN CORTES


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MELJUN CORTES

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

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


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Video

Video consists of two devicesthe 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


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CRT Monitors


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CRT

All CRTmonitors have a cathode ray tube(CRT),which is a vacuum tube

One end of this tube is aslender cylinder that

consists of three

electron guns

The wide end of the

CRT is the display screen


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CRT

When power is applied to the electron guns, astream of electrons is generated

This stream is subjected to a magnetic field

generated by a ring of electromagnets called ayoke

The phosphor coating releases energy as visible

light when struck by the electrons Phosphors continue to glow momentarily after being

struckcalled persistence


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CRT Refresh Rates

CompTIA A+

Essentials

Essentials


8/84 2007 The McGraw-Hill Companies, Inc. All rights reserved

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 entirescreen and get the electron

beam back to the start

Videodata is displayed on the monitor as the electron gunsweeps the display horizontally, energizing appropriate areas onthe 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, youll see flicker

If it is set too high, youll have a distorted screenimage and may damage the monitor

Multisync(multiple-frequency monitor) monitors

support multiple VRRs



Phosphors

Phosphors and shadowmask

Phosphorsare dots inside

the CRT monitor that glowred, green, or blue when

an electron gun sweeps

over them

Phosphors are evenly

distributed across the front

of the monitorOne group of red, green,and blue phosphors is calleda triad



Shadow Mask

Shadow maskis a screen that enables the properelectron 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 pictureelement, orpixel



Resolution

Monitor resolutionis always shown as the numberof horizontal pixels times the number of vertical

pixels

Some common resolutions are 640x 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 pitchdiagonal distance betweenphosphorous 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, whichproduces a

sharper, more defined

image



Bandwidth

Bandwidthnumber of times an electron gun canbe 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

Dont emit radiation

Called flat panels or flat panel displays



How LCDs Work

Liquid crystalstake advantage of the property ofpolarization

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 thattend 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 groovesoriented at a 90 angle

Molecules in the middle will try to line up to both

sidescreating 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 blurred

effect



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 varietyof colors, and hasa much widerviewing area


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LCD Components

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

LCD logic board uses DC

Cold cathode

fluorescent lamp

(CCFL) usedin backlights


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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 (68 ns) better

Low-end LCDs (2025 ns) have ghosting problems

Contrast ratio

Difference between lightest and darkest

Low end (250:1) to high end (1000:1)


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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


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Projector Features

LumensAmount 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

Expensivetypically a few hundred dollars


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Common Features

Overview Size

Connections

Adjustments


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Common FeaturesSize

CRT monitors measured in inches

Monitor size (not viewable area)

Viewable image size(VIS)screen size from diagonalcorners

LCD monitors usejust the VIS value

Monitor size VIS


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Common FeaturesConnections

Traditional CRT monitors usea 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 VGAAdapter


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Common FeaturesConnections

The Random Access Memory Digital-to-AnalogConverter(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 toanalog (RAMDAC not used)

Digital from video card sent and used as digital on

LCD monitor


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Common FeaturesAdjustments

Controls On/off button

Brightness/contrast button

Onboard menu system

Two main functions

of menu

Physical screen adjustments

Color adjustments


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Power Conservation

About half the power required by the PC isconsumed 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 1530 seconds to restore display


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Power Conservation

LCD monitor uses less than half the electricity asa 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


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Video Cards


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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


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Video RAM

Text video cardsdisplay only the 256 ASCII characters Older systems displayed on 80 chars/row and only 24

rowsonly 1920 bytes of RAM needed

Graphics video cardscould 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 depthis represented as bits (color depth of 24 bits) and not thenumber of colors


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Color Depth

Color depthis 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 Bits

2 colors 1 bit (mono)

4 colors 2 bits

256 colors 8 bits

64,000 colors 16 bits

16.7 million colors 24 bits

16.7 million colors

8-bit opacity

32 bits


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Video Modes

VGA (640 x 480) Beyond VGA

SVGA, XGA, and more

Mode Resolution Mode Resolution

QVGA 320 x 240 WSXGA 1440 x 900

WVGA 800 x 480 SXGA+ 1400 x 1050

SVGA 800 x 600 WSXGA+ 1680 x 1050

XGA 1024 x 768 UXGA 1600 x 1200WXGA 1200 x 800 HDTV 1080 1920 x 1080

HDTV 720 1280 x 720 WUXGA 1920 x 1200

SXGA 1280 x 1024 WQUXGA 2560 x 1600


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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


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AGP Benefits AGPis 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 clockcycle

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


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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


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Graphics Processor

The most important decision in buying a videocard is the graphics processor

Most video processors are made by

NVIDIA

ATI

ATI Radeon X1950 XTX512 MBATI Manufacturer

Radeon X1950 XTX Processor & Model

No.

512 MB Amount of RAM


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Graphics Processor

NVIDIA and ATI release multiple models ofgraphics processors each year

Most features only seen in 3-D games

Textures

Transparency

Shadows

Reflection

Bump mapping


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Video Memory

Video RAM constantly updates to reflect everychange that takes place on screen

Three bottlenecks

Data throughput speedAccess speed

Simple capacity

Overcome bottlenecks in three ways

Wider bus between video RAM and video processor

Specialized super-fast RAM

More RAM


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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


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Video Memory

Video RAM Technologies

Acronym Name Purpose

VRAM Video RAM Original

WRAM Windows RAM Never caught on

SGRAM Synchronous

Graphics RAM

Special SDRAM

DDR SDRAM Double Data Rate

SDRAM

Used on budget

graphics cardsDDR2 SDRAM DDR Version 2 Replaced with GDDR3

GDDR3 SDRAM Graphics DDR V. 3 Faster DDR2

GDDR4 SDRAM Graphics DDR V. 4 Upgrade of GDDR3


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Installing and Configuring

Video Software


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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 newvideo 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 AGPcard empty to allow better airflow

Software


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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 manufacturers

Web site for updates

2. Check the drivers Use the Display applet

Display Applet


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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


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Display Applet

Screen Saver

Power Management

features

Covered in Chapter 19


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Display Applet

Settings tabAllows you to configure multiple monitors

Can configure resolution and color depth

Display Applet Advanced


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Display AppletAdvanced

Monitor tab

Can update monitor driver

Can set the screen refresh

rate

Change in small increments

Can cause damage


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Display AppletAdvanced

Many video cards have card-specific tab

Color Correction Can adjust screen colors

Rotation Portrait or Landscape

Modes Very advanced settings

Usually not needed


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Working with Drivers

Video drivers work same way as other hardwaredrivers

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


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IT Technician

CompTIA A+Technician

3-D Graphics


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3-D Graphics

Improvements driven by gamesAlthough improvements used in other applications

such as computer aided design (CAD)

First-person shooters (FPSs) such as Wolfenstein3D and Doom started move to 3-D


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Transformation and Sprites

Movement of 3-D objects referred to astransformation (CPU intensive)

Intels SIMD and AMDs 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


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3-D Objects

The second generation produced 3-D objects thrua 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)


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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 fortextures and fast processors for transformations

Application programming interfaces (APIs) created

to talk to hardware directly OpenGL ported from UNIX

DirectX (Microsoft only)


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DirectX and Video Cards

DirectX provides direct access to hardware asfollows:

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


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DirectX Diagnostic Tool

Accessories | System Tools | System Information

Tools | DirectX Diagnostic Tool

OrRun DXDiag


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Web sites

Some useful Web sites to visit before making ahardware-buying decision

www.arstechnica.com

www.hardocp.com www.tomshardware.com

www.sharkyextreme.com
http://www.arstechnica.com/http://www.hardocp.com/http://www.tomshardware.com/http://www.sharkyextreme.com/http://www.sharkyextreme.com/http://www.tomshardware.com/http://www.hardocp.com/http://www.arstechnica.com/


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Troubleshooting Video


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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


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Video Card HW Problems

Hardware problems usually justone of two

Fan has gone out

RAM is faulty

Faulty hardware

symptoms

Bizarre output

May see mouse moving

Display is a mess


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Video Card Problems

Dont forget the obvious If everything is sideways, check the rotation settings

Limited colorscheck the color depth

Resolution set too high Input signal out of range


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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!


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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


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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


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Common ProblemsCRTs

You may be able to fix this Big color blotchesdegauss it with degauss button

Its probably beyond fixing Dim display (with brightness turned up)

Take it in to a repair shop Out of focusadjustment near the

flyback transformer

Hissing or sparking sounds Bird-like chirping sounds

Single horizontal or vertical line

Single white dot on a black screen


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External controls provide users with the opportunity to fine-tune the monitors 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 soundits normal


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Troubleshooting CRTs

Convergence defines how closely the three colorswill 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 wont give you the schematics

Leave to a trained specialist

High-Voltage Anode


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g o age ode

Under the suction cup is the

actual high-voltage anode

The wire leading from thesuction cup goes to theflyback transformer

Theres a big capacitor thatcan hold up to 25,000 voltsof charge for days, weeks,months, or even years

Lifting this

suction cup willalmost certainly

kill you!

High-voltage anode


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Do NOT attempt todischarge a monitor

unless properly trained

and equipped

Discharging a CRT


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Common ProblemsLCDs

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


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Cleaning Monitors

Anti-static monitor wipes or anti-static clothsshould be used for cleaning the monitor

Do not use window cleaners

Avoid commercial cleaning solutions on

LCD screens


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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


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SLI and Crossfire

Splitting the processing load between two ormore GPUs

NVIDIA calls theirs Scalable Link Interface (SLI)

ATI calls theirs CrossFire

Two video cards installed and connected with a

bridge card


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TV and PCs

TV Out connects computer to TV

Tuner cards

Allows PC to mimic some

features of Tivo

HDMI (High Definition

Multimedia Interface)

Designed to replaceDVI connections


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TV and PCs

Plasma Not suited for PCs

Odd native resolutions (such as 1366x768)

Burn-intendency 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


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Documents

MELJUN CORTES Computer Organization Lecture Chapter17