dhelix.bas

101 SCREEN 0:WIDTH 40:LOCATE 12,7,0:COLOR 5:PRINT "      The Double Helix    " :LOCATE 13,7,0:COLOR 9:PRINT"    --------------------":LOCATE 14,7,0:COLOR 1:PRINT"     Jason  Vroustouris ":T=TIMER
102 IF T+16>TIMER GOTO 102 ELSE:CLS:SCREEN 2:WIDTH 80:X=10:Y=100:XD=1:YD=1:A=50:B=0:AD=1:BD=1:AS=1:BS=1:XS=3:YS=3:SX=640:SY=200:P=1:XX=X:YY=Y:XXD=XD:YYD=YD:AA=A:BB=B:AAD=AD:BBD=BD:P=1
103 A$=INKEY$:IF NOT A$="" THEN SYSTEM ELSE IF X>640 THEN
XD=-XS:P=P+1
104 IF XX>640 THEN XXD=-XS:P=P+1
105 IF X<0 THEN XD=XS:P=P+1
106 IF XX<0 THEN XXD=XS:P=P+1
107 IF Y>200 THEN YD=-YS:P=P+1
108 IF YY>200 THEN YYD=-YS:P=P+1
109 IF Y<0 THEN YD=YS:P=P+1
110 IF YY<0 THEN YYD=YS:P=P+1
111 IF A>640 THEN AD=-AS:P=P+1
112 IF AA>640 THEN AAD=-AS:P=P+1
113 IF A<0 THEN AD=AS:P=P+1
114 IF AA<0 THEN AAD=AS:P=P+1
115 IF B>200 THEN BD=-BS:P=P+1
116 IF BB>200 THEN BBD=-BS:P=P+1
117 IF B<0 THEN BD=BS:P=P+1
118 IF BB<0 THEN BBD=BS:P=P+1
119 R=R+1:IF R>100 THEN XX=XX+XXD:YY=YY+YYD:AA=AA+AAD:BB=BB+BBD:IF P>12 THEN P=1
120 PALETTE 1,P:X=X+XD:Y=Y+YD:A=A+AD:B=B+BD:LINE(A,B)-(X,Y),1:LINE (AA,BB)-(XX,YY),0:GOTO 103