[Coco] Artifact purple/green wasRe: CoCo Monitor

[Robert Gault]

KnudsenMJ at aol.com wrote:
><snip>
> B W B W ...
> W B W B ...
> B W B W ...
> 
> Do you get purple?  Hard to believe I never tried that one -- Mike K.
> 

Here is a very slow example which will give either purple or green.

10 PMODE3,1:PCLS0
20 C1=0:C2=1
30 FOR V=0TO10
40 FOR H=0TO255STEP2
50 PSET(H,V,C1):PSET(H+1,V,C2)
60 T=C1:C1=C2:C2=T
70 NEXT H
80 T=C1:C1=C2:C2=T
90 NEXT V
100 PMODE4,1:SCREEN1,1
110 GOTO110

If you want to use artifact colors, it is faster to create small blocks 
of the needed color and then PUT them to the screen.

The above pattern is
XXOOXXOOXXOOXXOO
OOXXOOXXOOXXOOXX
XXOOXXOOXXOOXXOO
which flips the colors both horizontally and vertically rather than just 
vertically.