100 REM ********** SIN CURVE
110 :
120 COLOR ,,,,0:SCREEN 3,0:CLS 3
130 PI=3.14159
140 OX=120:OY=200:R=100:RXY=1
150 S=1024
160 LINE(0,OY)-(639,OY),7
170 LINE(OX,OY-160*RXY)-(OX,OY+160*RXY),7
180 LINE(OX+R,OY-160*RXY)-(OX+R,OY+160*RXY),7
190 CIRCLE(OX,OY),R
200 FOR TH=0 TO 2*PI STEP PI/S
210   X=R*COS(TH):Y=R*SIN(TH)
220   PX=X+OX:PY=-Y*RXY+OY
230   T=TH*200/PI+OX+R
240     IF TH<PI/2 THEN C=2 :GOTO *L
250     IF TH<PI   THEN C=3 :GOTO *L
260     IF TH<3*PI/2 THEN C=5:GOTO *L
270     C=1
280     *L
290   LINE(OX,OY)-(PX,PY),C
300   LINE(T,OY)-(T,PY),C
310 NEXT TH
320 END