[Coco] Coco-3 to the GBS-8220 upscaler interfacing

[mike delyea]

What do 40 and 80 column displays look like?


On Fri, Jun 6, 2014 at 4:44 PM, Kandur <k at qdv.pw> wrote:

> Progress report.
> Having read that, I just connected the H+V sync wires from the Coco,
> to a 10k pot's one side, the  GBS-8220 board's 'S' input to the middle,
> and a 1k resistor to the other side, the other end of it was grounded.
> Got a rock solid display. See the photos.
>
> http://qdv.pw/eng/_photos/Computers/Coco/coco-3%20to%20GBS-8220_6034.jpg
> http://qdv.pw/eng/_photos/Computers/Coco/coco%20screen_6013-1024.jpg
>
> Like you said, the display is ok, but not as good as on an analogue crt
> monitor,
> Can we have anyting better for $27 and free shipping?
> Would you mind to share the web site's url,  you quoted?
>
> Kandur
>
> Thursday, June 5, 2014, 5:16:30 AM, you wrote:
> > On Wed, 4 Jun 2014, Kandur wrote:
>
> >> Thanks.
> >> This circuit seem to assume negative sync inputs,
> >> while the Coco-3 has positive sync outputs.
>
> > From the web site:
> > <quote>
> > The sync signal combiner has a system to adjust to different sync
> > polarities so that it always makes correct
> > composite sync signals. VGA
> > card uses different sync signal polarities to tell the monitor which
> > resolution is used. This circuit adjusts to
> > sync signal polarity changes
> > in less than 200 milliseconds, which is faster than setting time of a
> > normal VGA monitor in the display mode change.
> > </quote>
> > It's actually a very clever design.
> > --
>
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