[Coco] RGB video on CoCo3

[Phill Harvey-Smith]

Success !

I have now got RGB working, and it provides a much better picture, for 
the first time I can actually use NitroOS9 in 80 column mode and read 
the text !

My problem was that I was not feeding +5V to Pin 16 on the SCART 
connector, so the TV was interpreting my signals as Composite video, 
which is why it was way to bright. Ended up examining my BBC micro scart 
cable which I knew worked, and was a machine of a similar age.

Once I did this I could feed the signals direct from the CoCo to the TV 
and it produced a picture without problems, though a little bright, 
placing a set of 120R resistors inline with theRGB signals seems to have 
brought the brightness down, though it does seem a little more noisy, 
maybe due to impedence mis-match....analog electronics was never my 
strong point.


One thing I did notice in ECB was that the CLS colours are slightly 
different :-

CLS	Composite/TV	RGB
0	Black		Black
1	Green		Green
2	Yellow		Blue
3	Blue		Orange
4	Red		Grey
5	White		White
6	Greenish	Yellow
7	Purple		Red
8	Pink		Light blue
9	Green/MS	Green/MS

Allowing for the fact that this is an NTSC CoCo3 on a PAL TV, though it 
is NTSC capable, and the fact that I'm slightly Red-Green colourblind, 
is this normal ?

Cheers,

Phill.


-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.