[Coco] More colors on CoCo 1?

Joel Ewy jcewy at swbell.net
Wed Jan 24 12:27:26 EST 2007


Richard E. Crislip wrote:
> <snip>
>   
>> Some amount of flicker is a given with this kind of thing.  The point is
>> just to see if it could be done.  If you would superimpose a G6R with a
>> dithered high-res bitmap over the color screen you could break up the
>> 4-pixel long blocks.  33%-50% of the time (depending on # of screens)
>> many of the big blocks of color would be broken up into high-res
>> pixels.  I don't know whether that would have any effect on perceived
>> flicker, but it would add detail.
>>     
> While reading this thread, a thought crossed my mind concerning the flicker 
> problem. Would john's VGA converter or Hawk's SVHS converter solve that 
> problem? Or are you relying on artifacting for additional colors?
>   
The idea here would be flipping between different graphics screens
rather than artifacting, though it would be interesting to see how
artifact colors would interact with 'real' colors.  SVHS should still be
at 15 KHz, but VGA usually starts at 30KHz.  But the real issue is how
fast the CoCo switches between screens.  Even if the screen refresh rate
has been doubled on the VGA converter to 30 KHz, I think the CoCo would
still be switching between 2 different screens at 15 KHz / 2.  I think
it would only make a difference if the 6847 was switching screens and
putting out horizontal sync pulses twice as fast.

JCE




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