[Coco] Artifact purple/green wasRe: CoCo Monitor

[Robert Gault]

Here is a short program that demonstrates about 200 different artifact 
colors. It is pretty good on a composite monitor, almost works with 
MESS, and is meaningless with RGB systems. I wish I could remember who 
wrote it and which magazine it was in, but I can't.

1 PCLEAR8
2 CLS
3 M=4:S=1
4 PMODEM,1:SCREEN1,S:PCLS
5 FORX=12TO255STEP17
6 FORY=2TO191STEP10
7 POKE178,N:N=N+1:IFN=256THENX=999:Y=999:GOTO9
8 LINE(X,Y)-(X+10,Y+6),PSET,BF
9 NEXTY,X
10 SOUND100,1
11 H=0:V=0
12 X=12+H*17:Y=1+V*10
13 LINE(X,Y)-(X+12,Y+8),PSET,B
14 A$=INKEY$
15 LINE(X,Y)-(X+12,Y+8),PRESET,B
16 IFA$=""THEN13
17 N=H*19+V
18 IFA$=CHR$(8)THENH=H-1:IFH<0THENH=0
19 IFA$=CHR$(9)THENH=H+1:IFH>13THENH=13
20 IFA$=CHR$(94)THENV=V-1:IFV<0THENV=0
21 IFA$=CHR$(10)THENV=V+1:IFV>18THENV=18
22 IFN>255THENSOUND200,1:GOTO12
23 IFA$="N"THENINPUT"SELECTED NUMBER IS";N:IFN>255THENPRINT"TOO 
LARGE":GOTO23ELSEIFN<0THENPRINT"TOO SMALL":GOTO23ELSEELSEGOTO25
24 CLS:H=INT(N/19):V=N-19*INT(N/19):PMODEM,1:SCREEN1,S:GOTO12
25 IFA$="/"ORA$="?"THEN31
26 IFA$=CHR$(32)THEN33
27 IFA$="B"THENPMODEM,5:SCREEN1,S:PCLS:POKE178,N: 
LINE(76,46)-(176,146),PSET,BF:FORQ=1TO200:NEXT:GOTO39
28 IFA$="M"THENM=M-(M=3)+(M=4):PMODEM,1:SCREEN1,S
29 IFA$="S"THENS=S-(S=0)+(S=1):SCREEN1,S
30 GOTO12
31 PRINTN
32 IFINKEY$=""THEN32ELSECLS:SCREEN1,S:GOTO12
33 PMODEM,5:SCREEN1,S:PCLS:COLORM+1,1:CIRCLE(126,96),65
34 POKE178,N
35 PAINT(126,96),,M+1
36 LINE(10,10)-(70,40),PSET,BF
37 FORJ=0TO180STEP35:LINE(40+J,180)-(255,180-J),PSET:NEXT
38 IFINKEY$=""THEN38ELSEGOTO39
39 FORZ=5TO1STEP-1
40 PMODEM,Z:SCREEN1,S:FORQ=1TO300:NEXTQ,Z
41 GOTO12

I've also lost the instructions so you will have to check the program to 
see what key strokes are monitored. If you run it on a Coco3, be sure to 
start from a WIDTH32 screen.