In <[log in to unmask]>, on 08/29/99
   at 05:01 PM, Uzi Paz <[log in to unmask]> said:

>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?
>Does it mean that the beam waits (1/51,000)-(1/53,600) seconds
>before it is triggered on the next line?  Is that necessary?

>Thanks,

>Uzi

Wait, no; necessary, yes.

There is some time required for the beam circuitry to reinitialize
to the starting positions of top of screen and left of screen.
These are the vertical and horizontal retrace or "blanking" times.
There are a also few small increments of time lost to syncing. The
beam isn't waiting, it's getting to the starting point.

jan lambert
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