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Re: RGB Card Question



Jorge ChB wrote:
Michael J. Mahon <mjmahon@aol.com> wrote:


No--actually, loss of color sync could result in some "rainbow"
displays for part of a frame as the monitor color reference
oscillator tries to get back into phase lock.


I know the rainbow effect, it happens when the frequency of the video
generator at the video source is offset for some reason. For example, if
the Apple II crystal frequency is offset in such a way that a fraction
of a 3.5MHz cycle is offset every 140 burst cycles, you get a very
beautiful rainbow effect going from left to right (not from top to
bottom) on the color monitor while showing a solid color on screen : the
bit stream slips off-phase along the scanline.

But I think you mean a rainbow going from top to bottom, as the monitor
tries to lock to the bursts as sucessive scanlines go passing by ?

It is usually a vertical rainbow, because of the typical PLL time
constant, but what you will see is dependent on the monitor.

-michael

Parallel computing for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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