Transcript Ch11

Video
Chapter 11
Overview
• In this chapter, you will learn to
–
–
–
–
Identify variations of CD media technology
Identify variants in DVD media technology
Install CD and DVD media drives
Troubleshoot CD and DVD media drives
Warning
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!
CRT and LCD Displays
Video
• Video consists of two devices - the video
card (or display adapter) and the
monitor
• The video card consists of two distinct
components – one to take commands
from the computer and update its own
onboard RAM, and
the other to scan
the RAM and send
data to the
monitor
Video Monitor Types
• Cathode ray tube (CRT)
• Liquid crystal display (LCD)
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 one or more of
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, when struck by
the electron beam, releases energy as
visible light
– The phospors continue to glow momentarily after
being struck – called persistence.
CRT Refresh Rates
Video data is displayed on the monitor as the electron gun
sweeps the display horizontally, energizing appropriate areas on
the phosphor coating.
• 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
CRT Refresh Rates
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
One group of red,
distributed
across the front green, and blue
phosphors is called
of the monitor
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 640X480, 800X600,
1024X768, 1280X1024,
and 1600X1200
• These resolutions match
a 4:3 ratio called the
aspect ratio
Dot Pitch
• Dot pitch defines the diagonal distance
between phosphorous dots of the same
color.
– The dot pitch can range from as high as .39 mm to
as low as .18 mm
– The lower the dot
pitch, the more
dots across the
screen which
produces a
sharper, more
defined image
Interlacing
• Interlacing is the process in which the
monitor sweeps or refreshes alternate
lines of pixels on the display
– It enables a low-end monitor to support faster
refresh rates by giving it twice as much time to
make a screen
– Can create eyestrain and headaches
Bandwidth
• Bandwidth defines the maximum number
of times an electron gun can be turned
on or off per second
– Bandwidth is measured in megahertz (MHz)
– How fast the monitor can put an image on the
screen
Maximum VRR = bandwidth

pixels per page
For example, a 17-inch monitor with a 100MHz bandwidth
and a resolution of 1024x768 can support a maximum VRR of
127 Hz:
100,000,000  (1024x768) = 127 Hz
LCDs
• Liquid Crystal Displays
–
–
–
–
–
Thinner and lighter
Much less power
Flicker free
Don’t emit radiation
Called Flat Panels or Flat Panel Displays
Light
• Travels in waves
• Wavelength determines the color
• If light came at us in one wavelength we
would see just one color
• We usually see many different
wavelengths which looks white
How LCDs Work
• Liquid crystals take advantage of the
property of polarization
• These crystals are composed of specially
formulated liquid, 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
LCD Matrix
• Calculators use static charging to darken
areas
• LCD screens use a matrix of wires to
provide a charge with greater precision
Passive Matrix
• Use three matrices to produce color
• Above the intersections of the wires add
tiny red, green, and blue dots
• The amount of voltage will allow
different levels of red, green, and blue
Dual-Scan Passive
Matrix
• Passive matrix is slow and tends to
create an overlap between pixels
• Dual-scan passive matrix is faster by
refreshing two lines at a time
– Still used on some lower-end LCD panels
Thin Film Transistor
(TFT)
• Thin Film
Transistor (TFT)
is also known as
the active matrix
• It uses one or
more tiny
transistors to
control each color
dot
• TFTs are brighter,
with better
contrast, can
handle a variety
of colors, and
have a much
wider viewing
area
LCD Resolution
• LCD panels come with a fixed number of
pixels, which is always equivalent to a
common resolution
• LCD panels cannot display more than
their pixel limitation
• Lower resolutions are faked by
estimating the pixels
Backlighting
• Backlighting is needed to improve
visibility
• LCD uses a type of cold fluorescent light
with prisms to spread light evenly across
the screen
– The measurement unit nits (candela/meter2) is
used to quantify the brightness of the backlighting
Contrast Ratios
• The contrast ratio is the difference
between the darkest and lightest spots a
monitor can display
– CRT monitors can display 450:1
– LCD monitors display 250:1
Monitor Size
• The size of CRT monitors is measured in
inches
• All monitors provide two numbers - the
monitor size and the actual size
• Viewable Image Size (VIS) is the
measurement of the actual screen from
one edge of the screen to the opposite
diagonal side
• LCD monitors just
use the VIS value
CRT Connections
• CRT monitors use a 15-pin, 3 row, DB
type connector, and a power plug
RAMDAC
• The Random Access Memory Digital-toAnalog Converter (RAMDAC) chip
converts digital signals into analog
signals for analog CRTs
• LCD monitors use digital signals and
need a circuitry for converting analog
signals to digital (analog LCD monitor)
RAMDAC
LCD Connections
• We now see LCD
monitors that use
digital video cards
(no RAMDAC) and a
totally different
Digital Video
Interface (DVI)
connector
– DVI-A (analog)
– DVI-D (digital)
– DVI-A/D or DVI-I
(interchangeable)
accepts either
Adjustments
• The on/off button,
the brightness and
contrast button, and
the onboard menu
system on the
monitor allow you to
make a number of
adjustments.
• The physical screen
adjustments and color
adjustments are the
two main functions
provided by all
monitor
manufacturers
Power Conservation
• Monitors that meet the VESA (Video Electronics
Standards Association) specification for display
power-management signaling (DPMS) can
reduce power consumption by roughly 75
percent
• Turning off the monitor with the power switch is
the most basic form of power management. It is
better to leave the monitor on if you have power
management!
• DPMS works with Windows Advanced Power
Management (APM) or Advanced Configuration
and Power Interface (ACPI) power management
software
The Video Card
The Video Card
A video card, also known as the display adapter, processes
information from the CPU and sends it out to the monitor.
• Video RAM stores
the video image
• Video processor
circuitry takes the
information from the
video RAM and
displays it on the
monitor
Video RAM
• Text video cards display only the 256
ASCII characters
– For a screen with 80 characters per row and 24
rows, you would need 80 characters x 24 rows
x 8 bits per character or 1,920 bytes of RAM
• Graphics video cards could turn any pixel
on or off
– A resolution of 320 x 200 pixels would require
64,000 bits (1 bit per pixel = on or off) or
8,000 bytes of RAM
– To add color you would need multiple bits to
define the color
• To display 256 colors it takes 8 bits. For true color (16.7
million colors) you would need 24 bits per pixel. Color
depth is usually represented as how many bits (color depth
of 24 bits) and not the number of colors.
Color Depth
Modes
• Monochrome text, color text,
monochrome graphics, and color
graphics are the four different types of
video cards that exist. Each of these is
called a video mode
• Modern video cards enable switching
between modes
• IBM and then VESA defined specific,
uniform video modes for video cards
Video Cards and
Standards
• Monochrome display adapter (MDA) card
– First text-only video card
• Color graphics adapter (CGA) card
– First-generation color display adapter that
supported colors
– Four-color screen offered 320x200 resolution
Video Cards and
Standards
• Enhanced graphic adapter (EGA) card
– Resolutions of up to 640X360 with 16 colors in text
mode, or 640X200 and two colors in graphics
mode. Late 1984
• Professional graphic adapters (PGA) card
– This standard offered 640X480 resolution, 3-D
rotation, and 60-frames/second animation
– Cost over $4,000 and used 3 ISA slots
– Aimed at engineering community
Video Cards and
Standards
• Video graphics array (VGA) standard
– 16 colors at a resolution of 640X480 pixels (1987)
– Often referred to as the minimum display
requirements on software packages
• Extended graphics array (XGA) standard
– 16-bit color at a resolution of 1024X768
• Super VGA (SVGA) standard
– Extensible standard - meaning that VESA adds to
the list as higher resolutions and deeper color
depths develop
Memory Requirements
• Different video modes require different
amounts of RAM on the video card
• The amount of video memory required at
a given resolution and color depth is
determined by multiplying the resolution
by the number of bytes of color depth
– 24-bit color uses 24/8=3 bytes per pixel
– Example: 800x600 with a 24-bit color depth
requires 800x600x3 =1,440,000 bytes of memory.
If your display adapter does not have that much
memory, then this mode would not be supported
Accelerated Graphics
Port
• AGP is a single special port, similar to a PCI slot,
which is dedicated to video
– Derived from the 66 MHz, 32-bit PCI 2.1 specification
– Uses its own personal data bus (PCI is limited to 32-bit
transfers at 33 MHz or bandwidth of 132 Mbps – it
cannot handle some of the video demands), and
supports pipelining (the steps required to process a
command)
Graphics Processor
• The most important decision in buying a
video card is the graphics processor
• Most video processors are made by
–
–
–
–
NVIDIA
ATI
Matrox
Third-party video card manufacturers use one of
these video processors on their cards
Video Memory
• The video RAM constantly updates to reflect
every change that takes place on the screen
• Low cost video cards ($50-$100) use standard
DRAM for video data storage
• DRAM needs to be refreshed 18.5 times per
second. Also, the access/response time of DRAM
is 50 nanoseconds or longer. These bottlenecks
are overcome by:
– Increasing the width of the bus between video RAM and
the video processor
– Using specialized RAM
• Most of the graphics rendering and processing is
handled on the card by the video processor
rather than the CPU
Video Memory
• The three styles of RAM specifically designed
for video are:
– Video RAM (VRAM)
• Dual-port memory that can send and receive at the same time.
• DRAM can only send or receive at a given time
– Windows RAM (WRAM)
• Dual-port memory that is slightly faster than VRAM
– Synchronous graphics RAM (SGRAM)
• Synchronized to the system clock
• Extremely fast
• Newer, generalized RAM types such as
Double Data Rate SDRAM, are often used
instead of the specialized video memory
above
Physical Installation
Issues
• High end video cards are tall and may
not fit in all cases
• High end video cards run very hot
– Leave the slot next to an AGP card empty to allow
better air flow
Installing and Configuring Video
Software
Drivers
• As a general rule,
uninstall the old video
card’s drivers before
installing the new
ones
– Choose the Settings tab
of the Display applet
– Then click on the
Advanced button and
choose the Adapter tab
– Click on Properties for
the adapter card and
then the Driver tab
• Check the
manufacturer’s
website for updates
Display Applet
• Found in Control
panel or alt-click on
the desktop and
choose Properties
– Settings tab
Monitor
• The monitor tab
allows you to update
the driver for your
monitor and to set the
screen refresh rate
– Using a higher refresh
rate than your monitor
is capable of can ruin
the monitor very
quickly
3-D Graphics
• 3-D graphics produce new levels of
realism on the computer screen
– Used for gaming and Computer Aided Design
(CAD) programs
– Early 3-D graphics required proprietary computer
systems and were used almost exclusively for CAD
– In 1992 a small company called id Software
launched Wolfenstein 3D and a whole new world of
gaming opened up
Sprites
• 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
– The vertices were connected with lines to produce
edges
– The edges form triangles that create polygons
– The last step is adding a texture (or skin)
Transformations
• Transformations are the calculations that
are necessary to produce movement by
the 3-D objects
– Very taxing on video cards and the PC
– The process of rendering an object and perform
transformations every 1/24th of second is very
demanding!
– 3-D video cards have massive amounts of RAM to
store textures and fast processors to handle the
transformations
– We talk to these cards using a standardized set of
instructions that any 3-D game can use – OpenGL
standards and DirectX
DirectX
• 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 menu  DirectX
Diagnostic Tool
Websites
• Here are some useful websites to visit
before making a hardware-buying
decision:
– www.arstechnica.com
– www.tomshardware.com
– www.sharkyextreme.com
Dual Monitors
• Windows systems
having a video card
with dual outputs can
be converted into a
multi-monitor system
with minimal effort
– You may also just install
multiple video cards
• The Display
Properties dialog box
can be used for
configuring multiple
monitors
Troubleshooting Video
Video Card Problems
• Improper drivers, poor connections, and
bad monitors
• On the rare occasion where the video card
is the problem, it is usually the video RAM
– Fixed speckles or spots on the screen
– Funny colors in Windows (provided they also appear
when booting in Safe mode)
– Screen decay (usually the VRAM hasn’t been properly
inserted in the sockets)
Warning
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!
Suicide
Lifting this
suction cup will
almost certainly
kill you!
• Under the suction cup
is the actual highvoltage 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
Discharging a CRT
Do NOT attempt to
discharge a monitor
unless properly trained
and equipped!
Troubleshooting
Monitors
• External controls provide users with the
opportunity to fine-tune the monitor’s image.
– Brightness, contrast, pin cushioning, trapezoidal
adjustments
– Monitors have a built-in circuit called a degaussing coil
to eliminate magnetic build up (a fuzzy looking monitor
may be fixed by degaussing it)
• Low-end monitors are generally susceptible to
convergence (when the three colors don’t quite
meet at a single point on the screen), and can be
set right by internal adjustments.
– Misconvergence is most likely near the edges of the
screen
Cleaning Monitors
• Antistatic monitor wipes or antistatic
cloths should be used for cleaning the
monitor
– Do not use window cleaners
– Avoid commercial cleaning solutions on LCD
screens
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
• Cracked LCD monitors
– Not repairable
– All other LCD problems are repairable
Common CRT Monitor
Problems
• Improper focus
– Adjustments are inside close to the flyback transformer
• Hissing or sparking sounds and the smell of
ozone
– Insulation rupture requiring a qualified technician
• Big color blotches
– Degauss
• Bird-like chirping sounds
– Monitor power supply
• Loss of brightness but the control is all the way
up
– Time for a new monitor
• Single horizontal or vertical line or single white
dot
– Repair shop
Do’s and Don’ts
• Do keep the screen
clean
• Do keep the cables
tightened
• Do use quality cabling
• Do use power
management
• Do dispose of
monitors properly by
checking with your
local waste disposal
company
• Don’t block the
ventilation slots
• Don’t use a refresh
rate higher than
recommended
• Don’t leave the
monitor on all the
time – even with a
screen saver
• Don’t place magnetic
objects like
unshielded speakers
close to the monitor
Video and CMOS
• Video setting for EGA/VGA has no
meaning
• Init Display First
– Determines which monitor to boot first in a multimonitor system
• Assign IRQ for VGA
– Try it each way – one way works and the other
doesn’t
• VGA Palette Snoop
– Not used today
• Video Shadowing Enabled
– Most video cards do their own shadowing – leave
off