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  1. Video Chapter 17

  2. 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

  3. 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 Video card Monitor

  4. CRT Monitors

  5. 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

  6. 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

  7. Essentials CompTIA A+Essentials CRT Refresh Rates

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

  9. 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

  10. 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

  11. 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 pictureelement, orpixel

  12. 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

  13. 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

  14. 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

  15. LCD Monitors • Liquid crystal displays • Thinner and lighter • Much less power • Flicker free • Don’t emit radiation • Called flat panels or flat panel displays

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

  23. LCD Components • Backlights illuminate the image • Inverters power the backlights (with AC) • LCD logic board uses DC • Cold cathode fluorescent lamp (CCFL) usedin backlights

  24. 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

  25. 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)

  26. 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

  27. 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

  28. Common Features • Overview • Size • Connections • Adjustments

  29. 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

  30. 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 VGAAdapter

  31. 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

  32. RAMDAC

  33. Common Features—Adjustments • Controls • On/off button • Brightness/contrast button • Onboard menu system • Two main functions of menu • Physical screen adjustments • Color adjustments

  34. 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

  35. 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

  36. Video Cards

  37. Video Card • Two major components • Video RAM • Stores the video image • Video processor circuitry • Takes information from video RAM and sends it to the monitor

  38. 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

  39. 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”

  40. Video Modes • VGA (640 x 480) • Beyond VGA • SVGA, XGA, and more

  41. 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

  42. 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

  43. 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

  44. Graphics Processor • 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

  45. 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

  46. 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

  47. 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

  48. Video Memory • Video RAM Technologies

  49. Installing and Configuring Video Software

  50. Physical Installation Issues • Two primary issues • Long cards • Some video cards are tall and may not fit in all cases • Get a new case or new video card • 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