[Coco] Artifacting on LCD?

[LinuxRules]

Arthur Flexser wrote:
> Very nice to have someone on the list who was involved in the design
> of the original CoCo's VDG!
>
> Perhaps, then, you can answer a question I'm a little curious about.
> Did the designers realize from the outset the value that the artifact
> colors would have for enhancing the graphics that the VDG was capable
> of?  Or, was it more the case that it was seen as an unavoidable
> annoyance under NTSC that conceivably programmers might find uses for?
>   
To the best of my knowledge, it was a surprise. To me at any rate. Of 
course, I was new to the NTSC
standard anyhow. Terry might have known, or suspected. He had a much 
more thorough grounding  in
broadcast standards. I don't recall any discussion of that until we saw 
it on the tube and said "What the...???!!!".

My thought (then) was that we should fix it, but the realities of 
schedules said No Way.....
I had thought that it was fixed later when a junior engr took over the 
project, but it must
have never gotten beyond the "talking stage". He is responsible for the 
T1 variant, though.
So maybe by that time, the artifact colors were being used and customer 
pressure demanded
that they stay. Or maybe it _can't_ be fixed, but is simple a fact of 
life when your data rate
reached the right (wrong) point.......Lots of fog in my head about 
timings and decisions.....

cheers,
johnd
JohnDumas at austin.rr.com
> I do recall that the original CoCo manual (and the VDG spec sheets?)
> made no reference to artifact colors.  PMODE 4 was described as a
> 2-color mode and there was no support for artifact colors under BASIC.
>  Perhaps that was done so the same manual could be used in countries
> using the PAL standard?
>
> I guess the value of artifact colors for graphics would have been
> fairly obvious if there were well-established micros prior to the CoCo
> where programmers made profitable use of them.  Was that the case,
> anybody know?
>
> Art
>