10 REM CIRCLE
   20 FRAME CLEAR:FRAME COLOR 10
   30 INPUT "RADIUS?";RD
   40 OX=128:OY=96:PLOT COLOR 7
   50 F=1-RD
   60 FX=0
   70 FY=-2*RD
   80 X=0:Y=RD
   90 GOSUB 2000
  100 DO
  110 IF F>=0 THEN Y=Y-1:FY=FY+2:F=F+FY
  120 X=X+1:FX=FX+2
  130 F=F+FX+1
  140 GOSUB 2000
  150 LOOP UNTIL X>=Y
  900 GOTO 30
 1900 END
 2000 REM PLOT
 2010 PLOT PIXEL OX-X,OY-Y
 2020 PLOT PIXEL OX+X,OY-Y
 2030 PLOT PIXEL OX-X,OY+Y
 2040 PLOT PIXEL OX+X,OY+Y
 2050 PLOT PIXEL OX-Y,OY-X
 2060 PLOT PIXEL OX+Y,OY-X
 2070 PLOT PIXEL OX-Y,OY+X
 2080 PLOT PIXEL OX+Y,OY+X
 2100 RETURN