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

[Kandur]

Thanks. 
This circuit seem to assume negative sync inputs,
while the Coco-3 has positive sync outputs.

Kandur

Wednesday, June 4, 2014, 4:18:28 AM, you wrote:
> On Tue, 3 Jun 2014, Kandur wrote:

>> Recently I got nostalgic and bought a Coco-3 on eBay, got it running and 
>> trying to run NirtOS-9 on it. I really have to start from scratch, I 
>> seem to have forgotten everything I knew about the Coco. At the moment 
>> I'm trying to interface my Coco-3 with an LCD VGA monitor, using the 
>> GBS-8220 upscaler board. I need to fix the sync somehow, to make the 
>> output more stable. I read a post here from Gene, he used a 74LS04 to 
>> combine the Coco's HSync and VSync outputs then connected them via 1n914 
>> diodes to a 1800 ohm resistor, and to the S pin of the GBS-8220 board. 
>> He wrote:  '(see the schematic)', but I can't see it. (: Any help 
>> regarding the Coco-3 to the GBS-8220 board interfacing would be much 
>> appreciated.

> See:
> http://www.epanorama.net/circuits/vga2rgbs.html

> The second diagram (VGA to RGB+CSYNC) will do
> the trick.  It's probably 
> possible with fewer gates, but this circuit
> works very well.  Having said 
> that, the GBS-8220 board does not yield a very
> clean display.  Definitely 
> useable, but not pretty.



> --