[Coco] GBS-8200 RGB to VGA

[George Ramsower]

I wired it almost exactly as each wire is designated except for the 
Horizontal line. I cheated and used the video output from the coco to 
steal a proper H sync from. However, in OS9, I had to use "Montype M" to 
turn off the color burst because it was messing with the sync in the 80 
column mode. 32 and 40 were fine. When I feel like it, I'll put a proper 
7402 chip in line with the H sync line from the coco to invert that 
signal. Gene Heskett thinks he may have used a 7406 which does the same 
thing but for more power on the output.
George R.

On 9/2/2015 7:21 PM, Steve Batson via Coco wrote:
> While I'm using the RGB2VGA solution based on the DE0-Nano...I'd love to see the final design of what you are doing. I have a GBS-8200 card, cables and everything wired and ready to go. I'd like to see it working even if it doesn't get much use :)
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> On Sep 1, 2015, at 10:41 PM, George Ramsower <georgera at gvtc.com> wrote:
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>> So before I found out this was a bad choice, I ordered and paid for the cheap Chinese RGB to VGA converter board.
>> While waiting for it, I began to learn that the H signal from the Coco is inverted and an inverter chip will be necessary to correct that...bummer.
>> Then I read that another fellow was connecting a Coco 3 to an SCART to VGA converter board and he found the same problem with the inverted H&V signals from the Coco. He used the Video out and mixed them for the SCART to use and it worked for him.
>> I tried something like this on the GBS8200 but I only put the video out from the Coco on the H line on the converter.
>> It works beautifully in 32 and 40 column modes but the 80 mode does jump up and down a bit. Otherwise it is great looking.
>> Tomorrow I'm going to play with it some more but, this looks really promising. I've simply connected the video out directly to the H input on that converter. Next I'm going to play with levels and resistors and caps, I might even play with the vertical line also but, I have a pretty good feeling this GBS 8200 is going to work just fine.
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>> George R.
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