Karbosguide.com - Module 7b.2

The video card (continued)


The contents:

  • About accelerator cards
  • About video card and chips
  • Card brands
  • The video driver
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  • About the accelerator cards

    In the early nineties the accelerator video cards appeared. Today all cards are accelerated and they are connected to the CPU through high speed buses like PCI and AGP.

    With accelerated video chips, Windows (and with that the CPU) need not calculate and design the entire bit map from image to image. The video card is programmed to draw lines, Windows , and other image elements.

    The CPU can, in a brief code, transmit which image elements have changed since the last transmission. This saves the CPU a lot of work in creating screen images. The video chip set carries the heavy load:

    All video cards are connected to the PCI or the AGP bus, this way providing maximum data transmission. The AGP bus is an expanded and improved version of the PCI bus - used for video cards only.

    Modern video cards made for 3D gaming use expensive high-end RAM to secure a sufficient bandwidth. If you for example want to see a game in a resolution of 1280 x 1024 at 80 Hz, you may need to move 400 MB of data each second - that is quite a lot. The calculation goes like this:

    1280 X 1024 pixels x 32 bit (color depth) x 80 = 419,430,400 bytes = 409,600 kilobytes = 400 megabytes.


    Cards and chips

    There are many manufacturers of video cards and accelerator chips. Some produce both cards and chips, while others only make one or the other. I have tried a lot of different cards. The tables below illustrate my personal evaluation. Some may disagree with my evaluation.

    First the best known video cards:


    Vendor Quality and price
    ATI High - Medium
    Cirrus Logic Low
    Matrox High - Medium
    NVidia High - Medium
    S3 Medium

    Here we see video card manufacturers:

    Vendor Quality and price
    ATI Medium - High
    Diamond Medium (High)
    Matrox High
    Creative Labs Medium (High)
    Orchid Medium (High)
    STB Medium - High
    Britek/Viewtop Low

    You can use these tables, when you buy a PC and/or video card. Make sure to start with a quality video card!


    The driver almost the most important part

    The difference between good and mediocre cards is clearly visible in their software. The companies ATI, Matrox, and Creative Labs deliver excellent drivers with their cards. They allow their cards to provide optimum screen performance.

    In contrast I can mention the ET 6000 accelerator chip, which was introduced in the mid 1990s. It had very fine specifications and scored very high in various tests. I bought a couple of cards with that chip, but I could never get them to work properly. The driver programs are poorly written, for example the refresh rate is not adjustable. Such cards are all right for low quality monitors, but not for monitors with high specifications. For these the refresh rate should be adjustable.

    Here you see a section of a Matrox video card control box. The driver knows precisely which refresh rates the monitor will tolerate at different resolutions:

    Another problem area is in the screen fonts, which come with the driver programs. Screen fonts are models for the letters seen on the screen. There are significant quality variations in this area. Again, ATI and Matrox are worth mentioning.


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    To learn more

    Read about video basics in Module 7a.

    Read about sound cards in Module 7c .

    Read about digital sound and music in Module 7d .

    Read about FPU work in 3D graphics.

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