[Coco] RGB2VGA on DE0-Nano (improvements)

[Gene Heskett]

On Friday 29 August 2014 07:31:55 Luis Antoniosi (CoCoDemus) did opine
And Gene did reply:
> Here, for the non-believers:
> 
> https://www.youtube.com/watch?v=R_QPRTTm5dY
> 
> 
> Luis Felipe Antoniosi

Looks fairly good, Luis.  The crawling edges you see are an artifact of a 
miss-match between the NTSC capture dotclock, and the NTSC dot clock.  
They need locked together, or better yet, if the horsepower is available 
in the DE1, to sample and lock clocks.

But I know nothing of coding for the DE1.  dot clock locking is probably 
very easy to do, but any sampling is likely something that would need 
addressed not by grabbing the RGB output of a software GIME chip or a 
6847, but by grabbing the data straight from memory as it is delivered to 
those chips and generating the VGA completely external to any emulation of 
the coco's color generating chips.

The lack of an adequately sized RGB output transistor in the existing 
hardware GIME is a very sore point with me as it renders the blue in 
particular, way to slowly to be usable in any text related mode.

We could, with todays tech, build a GIME that could do this video 
generation at VGA speeds, and do it on 25% of the power the GIME uses.

But we don't have the million plus it would take in NRE costs to make the 
masks and perhaps 1k of them as dropin replacements.  How many of us would 
spend a 5000 dollar bill for a GIME chip that actually did it right?  
Thats right, zero.

But don't forget, the game folks, with the coin operated games by the 
jillions are also potential customers if we could do it right, and cheap 
enough.  If it took off in that arena, the potential market isn't 500 to 
1k chips, but 5 to 10 million.  With that sort of quantity, we might be 
looking at a $35 break even on the NRE.

But the dreaming is still free. ;-)

Cheers, Gene Heskett
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