10 REM >TestSnd
   20 ON ERROR MODE 7:PROCoff:END
   30 *FX229,0
   40 *FX156,86,0
   50 *FX7,7
   60 *FX8,7
   70 *FX3,5
   80 MODE 4
   90 VDU 23,1,0;0;0;0;
  100 V=13:P=0:M=13:G=64:D=0
  110 DIM X(V,M),Y(V,M),S(360)
  120 FOR S=0 TO 2*PI STEP PI/180
  130 S(D)=SIN(S):D=D+1
  140 NEXT
  150 FOR B=1 TO M
  160 FOR A=1 TO V
  170 X(A,B)=-109+107*(A-A*B/21+B/3)
  180 NEXT:NEXT
  190 REPEAT
  200 FA=0.15*RND(100)
  210 FB=0.15*RND(100)
  220 F=FA/5
  230 FOR Y=1 TO M
  240 D=1
  250 FOR X=1 TO V
  260 D=D+F
  270 Y(X,Y)=27.7*Y+(S(D*FA MOD 360)+S((P+D*FB)MOD 360))*G+50
  280 NEXT
  290 P=P+20
  300 NEXT
  310 CLS
  320 FOR Y=1 TO M
  330 MOVE X(1,Y),Y(1,Y)
  340 FOR X=1 TO V
  350 PLOT 5,X(X,Y),Y(X,Y)
  360 NEXT:NEXT
  370 FOR X=1 TO V
  380 MOVE X(X,1),Y(X,1)
  390 FOR Y=1 TO M
  400 PLOT 5,X(X,Y),Y(X,Y)
  410 NEXT:NEXT
  420 UNTIL FALSE
  430 :
  440 DEF PROCoff
  450 *FX2,0
  460 *FX3,0
  470 ENDPROC