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Video. Section Objectives. After completing this section you will be able to: Describe the components of the video subsystem Differentiate among monitor types including laptop displays Define basic monitor theory and terminology Describe issues regarding video memory

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Section Objectives

After completing this section you will be able to:

  • Describe the components of the video subsystem

  • Differentiate among monitor types including laptop displays

  • Define basic monitor theory and terminology

  • Describe issues regarding video memory

  • Install a video adapter and associated software

Video Overview

  • Video should be considered a subsystem that consists of:

    • the monitor

    • the electronic circuits which send the monitor instructions

    • the connecting cable

Video Overview

Video subsystem

Video – Figure 10.1

Types of Monitors

  • Different ways of classifying monitors:

    • Color or Non-color

    • Analog or Digital

    • Type of video adapter used

Types of Monitors

  • Monochrome

    • First type to be produced

    • Project a single color (white, amber, or green) on black background

    • Text-only output, no graphics

  • Grayscale

    • Display varying shades of black and white

    • Used by artists and CAD designers

  • Color

    • Display up to millions of colors for text and graphics

Types of Monitors

  • Digital

    • Accept digital signals from the video adapter

    • First monochrome and first two types of color monitors

    • Limited number of colors

  • Analog

    • Utilize analog waveforms to generate colors

    • Color variations are limitless

      Note: Video adapter must match the type of monitor.

Types of Monitors

Video adapters/monitor types

Video – Table 10.1

Monitor Terminology and Theory

  • Monitor size

    • No industry standard, but traditionally defined as the diagonal length of the picture tube (or CRT).

    • Most common sizes are 15-inch, 17-inch, and 21-inch.

  • CRT (Cathode Ray Tube)

    • Main part of the monitor.

    • Covered by the monitor case which may not allow all of it to be viewed.

  • VIS (Viewable Image Size)

    • Listed by many manufacturers as the viewable area of the CRT to clarify the monitor size.

Monitor Terminology and Theory

  • Electron gun

    • Directs a beam of electrons at a phosphorous dot on the back of the monitor tube.

      • Some monitors have 3, one each for the colors red, green, and blue.

      • Other monitors utilize only 1 to direct the 3 color beams.

    • When the beam hits the phosphor, the dot glows on the front of the screen.

      • All figures, icons, and letters are made up of these glowing dots.

  • Dot triad (or dot trio)

    • 3 phosphorous dots grouped together at each location on the screen.

    • Consists of 1 dot each for red, green, and blue.

    • Electron beam hits the dot(s) with varying intensity causing the phosphor to glow and create different color intensities.

Monitor Terminology and Theory

  • Shadow mask

    • A metal plate with holes that keeps the electron beam directed (or focused) at the proper dot.

  • Pixel (short for picture element)

    • One dot on the screen created by the convergence of the phosphorous dot trio.

    • Smallest displayable unit on the monitor screen.

Monitor Terminology and Theory

Video theory of operation

Video – Figure 10.2

Monitor Terminology and Theory

  • Picture cell

    • The single image created by 3 different colored phosphorous dots.

  • Dot pitch

    • The distance between like-colored phosphorous dots on adjacent dot triads.

    • Measured in millimeters.

    • Commonly include .39mm, .35mm, .28mm, .26mm, .25mm.

    • The lower the monitor’s dot pitch, the smaller the distance between the dot triads. The lower the number, the better the picture quality.

Monitor Terminology and Theory

Dot pitch

Video – Figure 10.3

Monitor Terminology and Theory

  • Aperture grill

    • Used in monitors and televisions as an alternative method to the shadow mask using very fine vertical wires instead of holes.

    • Allows more electrons to reach the screen, producing deeper color intensities.

    • Requires horizontal stabilizing wires to keep the fine vertical wires from vibrating or moving and these can be viewed on bright images.

    • Minimum acceptable dot pitch for the aperture grill is .25mm.

    • Some dot pitch descriptions include:

      • Grill pitch, horizontal mask pitch, and mask pitch.

Monitor Terminology and Theory

Aperture grille

Video – Figure 10.4

Monitor Terminology and Theory

  • Resolution

    • The maximum number of pixels of a monitor.

    • Illustrated by two values separated by an x, meaning by.

      • Example of a monitor resolution is 640 x 480.

        • 640 = # of pixels that fit horizontally

        • 480 = # of pixels that fit vertically

    • Depends on the combination of the monitor and adapter.

Monitor Terminology and Theory

  • Refresh Rate

    • The maximum number of times a screen is scanned, or redrawn, in one second, measured in Hz.

  • Horizontal scanning frequency (HRR or Horizontal Refresh Rate)

    • The speed which the beam traverses the screen and draws one line.

    • Measure in kilohertz (kHz) as determined by the video adapter.

    • Range from 35 to 90 kHz.

Monitor Terminology and Theory

  • Vertical scan rate (VRR or Vertical Refresh Rate)

    • The number of times the electron beam draws from the top-left corner, to the bottom-right corner, and back again to the top-left, drawing the entire screen.

    • Determined by the capabilities of the video adapter and the monitor.

  • Multi-scan monitor (also multi-synch or multiple frequency)

    • Can lock onto different vertical and horizontal scanning rates.

  • Interlacing

    • A monitor that uses interlacing scans first odd numbered pixel rows, then returns for the even ones on each vertical refresh.

    • Causes a flickering screen, but is less expensive than non-interlaced, which scans all horizontal rows on each vertical refresh.

LCD (Liquid Crystal Display)

  • LCD (Liquid Crystal Display)

    • A video technology used with laptops and flat screen monitors.

    • The two types of LCD are passive matrix and active matrix.

  • Passive matrix (least expensive)

    • Made up of rows and columns of conductors, with the pixels located at each intersection.

    • Each pixel has 3 cells in a color monitor, one each for red, green, and blue.

    • Not as bright as active matrix displays.

LCD (Liquid Crystal Display)

  • Active matrix (more expensive)

    • Have a transistor for each pixel.

    • Number of transistors determine maximum resolution.

    • Also known as TFT(Thin Film Transistor), which use three transistors per pixel, one for each color.

    • Brighter than passive matrix.

  • Flat panel

    • Monitors for desktop computers that use LCD technology.

    • Viewing area the same as the LCD measurements.

    • Take up less desktop space, and use less power than CRTs.

LCD (Liquid Crystal Display)

Flat panel versus regular-sized monitor

Video – Figure 10.5

Video Ports

  • DVI ( Digital Video/Visual Interface)

    • Interface used on an AGP PCI-E adapter with the better flat panel monitors.

    • DVI port is a 24-pin connector.

  • Single link connection – Allows video resolution up to 1920x1080.

  • Dual link connection – The use of more pins sends more single allowing for higher resolution.

  • DVI-D – Type of DVI used for digital connectivity only.

  • DVI-I – Type of DVI used for both digital and analog monitors.

  • HDMI(High-Definition Multimedia Interface) - An upgrade to DVI which carries both video and audio over the same cable.

Video Ports

Video Adapter with S-video (TV Out),DVI and VGA Ports

Video – Figure 10.7


  • Projector – Projects what is being displayed on the computer onto a larger screen.

  • The connections for a projector are similar to those of a video card.

Monitor Preventive Maintenance

  • Cleaning the screen may be performed using anti-static wipes.

  • Do not get liquid near the edge of the CRT, it may leak into the monitor.

  • The case may be cleaned with a soft dampened cloth and one of the following:

    • Mild household detergent, glass cleaner, or isopropyl alcohol.

    • Spray cleaner onto the cloth, not the monitor.

Monitor Energy Efficiency

  • APM (Advanced Power Management)

    • Developed by Microsoft and Intel.

    • Allows BIOS to control hardware power modes.

  • ACPI (Advanced Configuration and Power Interface)

    • Microsoft introduced on Windows 98, 2000, XP, and Vista.

    • Expands control to power modes for CD/DVD drives, network cards, printers, and other attached devices.

Screen Savers

  • Screen Saver

    • Changes the image on the monitor constantly to keep any particular image from burning into the screen.

    • With old monitors, they were a necessity to prevent damage.

    • New monitors’ high refresh rates make screen savers unnecessary.

    • LCDs do not need the use of screen savers as they use a different technology than CRTs.

    • Provide a form of entertainment for the computer user.

    • Provide password protection for users.

Video Adapters

  • Video adapter

    • Controls most of the monitor’s output.

    • Use the PCI, AGP, or PCI-E interface.

    • Bus connects the video card to the microprocessor.

    • The bus interface, microprocessor, chipset, and video adapter can affect the speed of video transfer to the monitor.

    • Upgrading the chipset, microprocessor, and video adapter can improve video performance.

    • Some adapters have a video processor.

Video Adapters

  • Video processor (also called a video coprocessor or video accelerator)

    • Assists the video communication between the adapter and the microprocessor.

    • Can be up to 64- or 128-bit processors.

    • Controls many of the video functions otherwise controlled by the microprocessor for faster performance.

Video Memory

  • VRAM (Video RAM) and WRAM (Windows Accelerator Card RAM)

    • Dual-ported memory (have separate read/write paths) and can written to and read from simultaneously.

  • RDRAM (Rambus DRAM), SGRAM (Synchronous Graphics RAM), and MDRAM (Multi-bank Dynamic RAM)

    • Single-ported memory that cannot be written to or read from simultaneously.

Video Memory

Bits required for colors

Video – Table 10.6

Video Memory

Video memory requirement examples

Video – Table 10.7

Installing a Video Adapter

  • Make sure you have the correct interface type and an available motherboard slot.

  • Gather required tools.

  • Download the latest driver for the video adapter including any video BIOS updates.

  • Make sure the adapter has the driver required for the operating system you’re using.

  • Power off the computer.

  • Open the computer and install the video adapter in the proper slot.

  • Connect the monitor to the external video connector.

  • Power on the computer and install the video driver per the manufacturer’s instructions and the operating system’s controls.

Troubleshooting Video

  • Try simple solutions first:

    • Check power cables and that monitor is turned on.

    • Ensure monitor cable is securely connected to the video adapter.

    • Check settings and controls.

    • Check to see if any new software or hardware has been installed, or if an upgrade has occurred.

    • Replace subsystem components with known good ones.

  • Raster

    • A monitor’s brightness pattern – a bright white screen.

    • If it appears, most likely the problem is the video adapter.

  • Troubleshooting tips can be found on page 368 in the book.

Troubleshooting Video

  • Flyback transformer

    • Component that boosts the voltage to the high levels the CRT requires.

    • Frequently goes bad.

    • Check prices before replacing, may be more cost-effective to replace entire monitor.

  • Degausser (or degaussing coil)

    • Can remove CRT magnetization.

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