1. Video Chapter 16

2. Cathode Ray Tube (CRT) CRT’s are like a vacuum tube. The more slender end contains three electron guns, the wider end is the display screen. When power is applied to an electron gun, a ray of electrons shoots to the phosphor coated screen. The yoke is a field of electromagnets that controls the electron beam’s point of impact. Persistence – the phosphors continue to glow after being struck by the electron beam.

3. CRT, cont… Refresh rate: HRR (Horizontal Refresh Rate) – the speed that the electron beam moves across the screen VRR (Vertical Refresh Rate) – the amount of time it takes to draw the entire screen and get the electron guns back to the top of the screen. In 1980, NEC created a Multiple Frequency Monitor to get rid of a limit on VRR.

4. CRT, cont… Phosphors The CRT has three electron guns: One for red, one for blue, and one for green phosphors A shadow mask is used to make the electron gun fire the appropriate phosphor. Resolution The number of horizontal pixels times the number of vertical pixels. Always 4:3 ratio. One triad is a red, blue and green phosphors in a triangle shape.

5. CRT, cont… Interlacing Keep cost down by refreshing every other line of pixels on the display Bandwidth Is the amount of times per minute the electron gun can be turned on and off. An average computer runs at 150 MHz = on and off 150 million times per second.

6. Liquid Crystal Displays (LCD) Thinner and lighter, use less power, virtually flicker free Read about polarity on pages 982-985 LCD screen are created by cutting fine grooves into glass and dropping the liquid into the grooves, they naturally line up on their own. Placing another grooved sheet of glass at a 90-degree angle to the other sheet causes the liquid to further line up and create a nice twist.

7. LCD, cont… Older styled LCD monitors used crossing “X” and “Y” and charging them to cut off the light to the liquid in that area. Newer systems have a third plate of red, green, and blue dots. The amount of voltage would determine the color. Thin Film Transistor (TFT) Instead of “X” “Y” cables, two transistor cables are used to control each dot. Resolution

8. LCD, cont… (resolution) No triads on an LCD screen. LCD’s come with a set number of pixels which only allows the monitor to go to a resolution at the pixel limitation. Backlighting Backlighting improves visibility.

9. Monitor size CRT monitors list size is the actual size of the monitor diagonally The size of the screen is VIS - viewable image size LCD lists the VIS as the only size

10. Random Access Memory Digital-to-Analog Converter(RAMDAC) RAMDAC takes digital signals from the video card and turns them into an analog signal for the analog CRT. RAMDAC actually defines the bandwidth that the video card outputs. Some LCD monitors have this function built in, but it requires a standard SVGA input.

11. Digital Video Interface (DVI) Consists of 3 different connectors DVI-D is for digital DVI-A is for analog (and also back compatibility). DVI-A/D or DVI-I (interchangeable), for either DVI-D or DVI-A

12. Video Card Handles all video chores in the PC Composed of 2 main parts: Video RAM Video processor circuitry Video RAM stores the visual image. Many Modes: MDG (Monochrome Display Adapter) 9-pin female socket. CGA (Color Graphics Adapter) IBM first made, first color adapter. Up to 640 x 200 resolution

13. Video Cards, Cont… (Modes) EGA (Enhanced Graphics Adapter) Improvement to CGA standard Support up to 640 x 350 resolution PGA (Professional Graphics Adapter) Package costing over $4,000.00 Offered 640 x 480 resolution, 3-D rotation, and 60- frame/second animation. VGA (Video Graphics Array) 16 colors, 640 x 480 pixels XGA (Extended Graphics Array) Resolution could reach 1,024 x 768, 16-bit color

14. Video Cards, cont… (Modes) SVGA (Super Video Graphics Array) Exceeded 640 x 480 and 16 colors AGP (Advanced Graphics Port) Used pipelining commands Sidebanding-a second data bus that enable the video card to send more commands to the northbridge while receiving other commands at the same time The different modes require different amounts of RAM on the video card.

15. Video Memory Crucial to the operation of a PC Hardest working set of electronics on the PC Constantly updates to reflect every change that takes place on the screen Synchronous Graphics RAM (SGRAM) Most popular, specialized video RAM available Synchronized to system clock

16. Video Drivers Every video card has a quirk of some form that you must address in order to install the new driver correctly Many driver updates require you to first delete the current video driver before you install the new one.

17. When video cards go bad!!! The majority of problems in video can be attributed to improper drivers, poor connections, and bad monitors. When they break the only option is to throw them away The trick is to recognize the classic signs of bad video RAM. Fixed speckles or spots on the screen, can be any color, but are usually black The second symptom is funny colors in windows, looks like monitor is colored with colored film

18. When video cards go bad!!! Most common problem is screen decay The machine runs fine for a moment, until the cards heat up disconnecting the improperly inserted RAM and causing the very cool-looking but disturbing screen decay

19. Adjustments External adjustments – monitor adjustments Range from brightness and contrast – to the more sophisticated – pincushion ning and trapezoidal adjustments. Internal adjustments As hipped, most monitors don’t produce an image out to the limits of the screen because of poor convergence at the outer display edges. Never touch the high-voltage anode in a monitor, it can cause serious shock Read 1023-1027 on CRT problems and discharge

20. Beyond A+ Video Every standard CMOS setup shows an option for video support The default setting is invariably EGA/VGA Init Display First In multi-monitor systems, Init Display First enables you to decide between AGP and PCI as to which monitor initializes at boot Read on to learn about 3-D graphics and 3-D video cards pg. 1028-1035