[Coco] Artifacting (again)

[Ciaran Anscomb]

Robert Gault wrote:
> [artifacting]
> Don't get confused by the output of emulators. There is only one emulator that
> comes close to correct artifact appearance, MESS.

XRoar (no CoCo 3) does a reasonable approximation of the cross-colour.
It uses a heuristic though, rather than calculate the actual interference
from the harmonics of the high frequency luminance.  That's actually
something I intend to (optionally) do properly at some point...

> The Keil, and VCC emulators
> approximate the artifact effect by using pure white, black, red, and blue but
> these are not artifacts. As a result of this graphics on these emulators will
> look sharper than the same screen would be on a real Coco attached to an NTSC
> monitor.

Do NTSC CoCo3s also artifact in this way, then?  For some reason
I thought I'd read before that they provided a simple cross-colour
"palette".  Perhaps that was someone describing another emulator and I
got wires crossed.

..ciaran