At 05:01 PM 8/29/1999 +0300, you wrote:
>I just helpd a friend with setting the display for his computer.
>I wondered:
>instead of "refresh rates" he has:
>vertical frequency, and horizontal frequency.
>The vertical frequency is: 85Hz, which is the same as "refresh rate",
>As the resolution is 800x600, I gathered that as there are 600 lines
>along the vertical axis of the screen, and that thus
>horizontal frequency should be
>600x85Hz=51KHz,
>But the horizontal frequency is set to 53.6KHz, which is of the same
>order of magnitude but not the same.
>
>Why is that?

Uzi,

This is called 'overscan'  The VESA specification calls for about 4%
overscan (a few lines above, and a few lines below the actuall image).
There is no data there (all black, or beam-off), so you don't see anything
above or below the 600 lines.

I am not sure why that is the case, but I would suppose it is to allow the
beam to stabilize after the big jump to the top.  I know that doesn't apply
to the bottom, but that's all I've got.

HTH


J. Paul Jones
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http://www.mindspring.com/~jpjcet/

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