10 DEF SEG=1:FULLW2:CLEARW2:DX=85:DY=75:X=300:Y=100:COLOR1,1,1:PCIRCLEX,Y,30:LEY=0:WHILEKEY<>159:KEY=PEEK(&HFFFC01):DY=DY-30*(KEY=80)+30*(KEY=72):DX=DX-30*(KEY=77)+30*(KEY=75):X1=X+DX:Y1=Y+DY:DX=DX-65*(X<=30 AND DY<=0)+70*(X>=585 AND DX=0)
20 DY=DY-70*(Y<=30 AND DY<=0)+65*(Y>=315 AND DY>=0):X1=-585*(X1>585)-30*(X1<30)-X1*(X1<=585 AND X1>=30):Y1=-315*(Y1>=315)-30*(Y1<30)-Y1*(Y1<=315 AND Y1>=30):COLOR0,0,0:PCIRCLEX,Y,30:COLOR1,1,1:PCIRCLEX1,Y1,30:X=X1:Y=Y1:WEND