[Coco] Re: CoCo 3 to VGA

Torsten Dittel Torsten at Dittel.info
Mon May 24 17:27:00 EDT 2004

>I don't think we need the de-interlacing either.

I always wondered if there is an interlaced picture coming out of the
CoCo's modulator (just writing the same picture a second time). I made
some experiments with a 50Hz PAL CoCo2 in the 80s switching between two
PMODE4 screens with the 50Hz VSYNC interrupt, one containing the odd,
the second the even scanlines. I wondered if this would help to double
the vertical resolution (although the picture was flickering with 25Hz
at the horizontal lines contained in only one of the both interlaced
screens). I dont remember how it looked on a TV set (if I ever tried it
at all). On a green monochrome composite monitor it looked fine, but I
hadn't the impression of a doubled vertical resolution, just of adding
kind of greyscale to the picture (like anti-aliasing, everything looked

TV guys? Gene?


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