[Coco] VCC enhancement request - Corrections

[Robert Gault]

That did not get written correctly, maybe a "senior moment". :)

What I should have said is that I have a graphics program that uses a 640x225x4 screen. The 225 
vertical results from $FF99 being modified. Also the $FF9F HVEN is set so that there are 256 
horizontal bytes per screen on which the 640x225x4 is a window. A joystick scrolls over the whole image.
PMODE4 is a 256 width screen and with an NTSC composite monitor gives white, black, red, and blue 
colors. The 640 width covers the same screen size so the pixels are .04 the size which gives access 
to more phase relations to the NTSC color burst and therefore more artifact colors. Also there are 
four intensity levels vrs. two for the PMODE4 screen, so again more color possibilities.
If you use more than one screen pixel to represent the original image pixel, the matrix can produce 
256 colors (color blending) on screen without any flickering.

I would love to see this on an emulator for several reasons. Composite monitors are vanishing. PAL 
monitors don't give the same results as NTSC. Composite monitors definitely suffer resolution 
problems and electrical interference from the Coco and accessories while emulators on RGB systems 
are immune.

Robert

Robert Gault wrote:
> There have already been requests for better artifact color display with the composite monitor
> setting with the VCC emulator, which I second.
>
> More to the point all emulators which do provide artifact colors at least as good as MESS/MAME only
> generate them on PMODE4 screens. A real Coco3 will, with an NTSC composite monitor, generate
> artifact colors on any screen including an HSCREEN such as HSCREEN4 640x192x4 and with $FF9F HVEN
> set the 640x256x4.
>
> So if anyone is planning to improve the VCC video, please include artifact colors on the HSCREENs
> while working to improve the same on the PMODE screens.
>
> Robert
>