Video

What it is

• Collection of parts and software designed to put a picture on a screen

• Monitor shows you what is going on with software (and OS)

• Primary output device for PC

• Video card, or Display Adapter handles communication between CPU and monitor

CRT Monitors

• A LOT of high voltage, resist the urge to take it apart!

Electron Guns (3)

Yoke

Electron Beam

Phosphor Coating on inside of tube

Shadow Mask

How it works

• Electron gun fires a beam of electrons

• Path of electrons is shaped by the yoke (bent)

• Electrons strike the phosphors and make them glow

• Phosphors have persistence so they continue to glow after electron beam stops

Refresh

• Electron beams sweep from left to right – across then down to next line

Horizontal Refresh Rate

Raster Line

Vertical Refresh Rate

Adjustments

• Try not to do it; the manufacturer knows better than you do.

• The video card “pushes” the monitor – that’s where changes are made

Resolution

• Number of horizontal pixels by the number of vertical pixels

640x480

800x600

Aspect Ratio

• Ratio of horizontal to vertical pixels

• 4:3 for CRT and many LCD monitors

• 16:9 for wide-screen monitors (same as theaters use)

Dot Pitch

• One significant measure of value of monitor: more expensive = lower number

Dot PitchIn millimeters

Dot pitch of .28 or less gives a nice, sharp image.

At .35 it seems like you can see the dots (TV image)

LCD (Passive) Monitors

• Light travels in waves (one definition)

• Liquid crystals tend to align with grooved surface or magnetic field.

• Aligned crystals will allow light to pass through (no electrical potential)

• Apply electrical potential and no light passes through

• This is digital, rather than analog of CRTs

LCD Pixels

Passive Matrix

• Wires in “Y” and “X” directions

• Voltage on wires allowed light to pass

• Slow response: “smeared” image

• Laptops for early years and watches today

Thin Film Transistor (TFT)

• Also called Active Matrix

• Vast improvement over Passive Matrix

• One, or more, transistors control each color dot

• Brighter, better contrast, faster, more colors and wider viewing angle

Resolution

• LCDs have a native resolution – looks best there

• Mine is 1280x1024 @ 60 Hz (19”)

• Can run lower resolution, but picture sharpness suffers – even with anti-aliasing

• Object size does not “grow” quite as quickly as monitor size

Other Measures

• Contrast Ratio: Bright to dark 700:1

• Brightness: 400 nits or 400cd/m2

• Response time: 4 ms

Projectors

• Lumens = brightness of projected image

• Throw = size of image at a certain distance from screen

• Lamps get hot quickly, need a fan to cool them and are expensive to replace

Plasma Display

• PDP – Plasma Display Panel

• Wider viewing angle and richer picture than LCD panels

• Use a lot of electricity

• Suffered from “burn in” issues where image “ghosts” on the screen

• Overscan (picture larger than display) can cut off the taskbar

Monitor Size

• CRT’s are smaller (for same size) than LCDs

Monitor size 17”

Viewable image size

15.5”

CRTLCD

Screen S

ize

15” screen size

Connections

• CRTs only use analog, 15-pin connector

• LCDs can use either analog or digital connector – DVI-I

• Video cards use RAMDAC to convert digital to analog for display

Graphics Processing

Unit

Power Conservation

• Turn off the CRT to reduce power consumption or when you walk away

• Burn-in of image is a long lost art. Used to happen on older monitors.

• Typical CRT uses 120-200 watts; LCD’s use 40-75 watts

Adjustments

• On/Off switch

• Brightness and contrast buttons (CRT)

• Menu activate/select button for on-board menu system

• Seldom is there a “reset” button, so be careful

Video Cards

• Or Display Adapters

• Three parts: Video RAM, video processor circuitry and RAMDAC

• Early cards just shuffled BIOS bit-maps to the screen (put a dot here, and one there)

• Used small amounts of RAM

• 80 characters by 24 rows

Color Depth

• 16 colors = 4 bits

• 256 colors = 8 bits

• 64k colors = 16 bits

• 16.7 million colors = 24 bits

• VGA mode is 640x480 @ 16 colors

AGP

• Accelerated Graphics Port

• Single slot, never two

• 66 MHz, 32-bits wide

• Uses strobing for 2x, 4x and 8x transfers on each clock cycle

21

On its own bus

Video RAM

• VRAM – Video RAM – allowed read/write at same time

• WRAM – Windows RAM – optimized for moving windows around – died quickly

• Replaced with DDR, DDR2, GDDR3 and GDDR4, GDDR5 SDRAM

Graphics Processor

• Can be done by CPU (for on-board graphics) but not efficient

• ATI and NVIDIA make most GPUs

• New GPUs come out often; a challenge to keep up with models

• More dollars = newer GPU

• CPU with GPU = Accelerated processing unit (APU)

PCIe x16

• Serial communication

• 16 “lanes” or channels

• Replacement for PCI bus as cards become available (x1 and x4 variants)

• SLI – its either Scan Line Interleave or Scalable Link Interface – two video cards (matched set)

Installation

• Read the install manual first, not later!

• Remove old drivers first. Reset system to VGA mode on existing card

• Install new drivers

• Install new card

• Finish driver installation

• Try to keep other cards away from video

Display Applet

11

Drivers

• Windows can crash and require a re-install of OS simply by installing a new video card and not uninstalling the old video drivers first.

• Go to Add/Remove Programs to uninstall video driver. (Step 1)

• Insert CD for new card and start driver installation. (Step 2)

• Stop system where directed and install card. (Step 3)

• Finish driver installation.

If the Card went bad

• Can’t get to Add/Remove programs.

• Have to install card to get working display.

• Start up in Safe Mode; you can delete drivers in this mode.

• Load drivers for new card.

Color Correction

• Also called color temperature

• Device that fits on monitor and looks at the display

• Graphic artists use these so they can set colors exactly.

3-D Games

• Started with sprites – still images of an object; multiple images used to create depth

• True 3-D uses vertices to define points on an object which are then “edged” with flat polygons

• Last step is to cover the edges with texture(s)

• Takes a lot of computing horsepower

3-D Video Cards

• Graphical Processing Units (GPU) to do the 3-D rendering tasks

• Lots of RAM to store textures• We need standardized command sets to

allow communication between game and video card:– OpenGL for UNIX, then PC’s– DirectX API (Application Programming

Interface) from Microsoft

DirectX

• Supports Video, Sound, Network connections and Input devices

• Provides common interface for games – don’t have to write to specific video card

• Vista/7 wants DirectX 10, not 9.0c which most have in XP

• Dxdiag to determine version of DirectX

4

Troubleshooting Cards

• Video cards seldom fail, but might• Often a driver issue – Windows cares about

video card, but not monitor• You can go to Add/Remove Programs to delete

video driver• Try Safe Mode to see if problem “goes away” –

then you know it is driver (or setting)• Try another monitor – often a hassle, but well

worth the time• Check the settings for resolution, refresh & color

Troubleshooting CRTs

• Try another monitor, then get another monitor – don’t try to fix them, the dollars don’t work out

• Check the signal cable connections – loose cable will color the screen or miss colors

• Client with no video turned out to be failure to start up

And Now…

• Plasma Display Panels– Large screen sizes– Miniature florescent lights – three per pixel– Uses as much power as CRT– First ones had bad habit of burning out

• Digital Light Processing (DLP)– One mirror for each pixel– Don’t know how they move, but they do