[Coco] RGB --> VGA for CoCo: A success story

[Steven Hirsch]

On Sat, 15 Nov 2008, J.P. Samson wrote:

>
> On Nov 15, 2008, at 11:54 AM, Steven Hirsch wrote:
>> On Sat, 15 Nov 2008, J.P. Samson wrote:
>> 
>>> On Nov 15, 2008, at 11:24 AM, Steven Hirsch wrote:
>>>> This morning I finally got motivated and built an adapter to run RGB 
>>>> video from my CoCo 3 into the Wei-Ya ACV-011 RGB-->VGA converter.  I'm 
>>>> pleased to report that it works quite well!
>>> 
>>> Any plans to do a write-up on how you put this together, Steven?  How's 
>>> the quality?  Have you ever used Roy's converter to be able to compare 
>>> results?
>> 
>> There's not a whole lot to write up...  It's just a matter of building a 
>> cable with a 10-pin ribbon cable header on one end.  If you are not sharing 
>> the converter with other classic machines, you just splice the other end to 
>> the header supplied with the converter board.  The signals are just 1:1, 
>> connect Gnd, R, G, B, H-sync and V-sync and you're good to go.  The pinout 
>> for the bottom of the CoCo 3 is widely available.
>
> Nice and easy, that's for sure.  I'd guess that Roy's converter does a better 
> job, since it is specifically designed for the CoCo 3 and includes a filter 
> to absorb some of the vertical banding that is an artifact of the computer's 
> RGB output.  Roy's adapter has difficulty clearly resolving some color 
> combinations, though, making such text hard to read.

The vertical banding is very slight and appears on every classic computer 
I've run through a converter.  Even my pricey Highway Model 100 (used for 
Apple IIGS and Amiga) exhibits this.  In general, VGA CRT displays look a 
bit better than LCD units but since that defeats my goal I just live with 
it.

Someday I'll fiddle with a low-pass filter for the video signals to see if 
it can be cleaned up a bit more, but it's not really bothering me.

> I found a link describing the board you used:
> http://www.weiya.com.tw/products_detail.asp?le=english&fid=111&pid=118&top_fid=

That's the one.

Steve


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