Bouncing Ball

Program bounce;

var x,y,dx,dy,i: Integer;

begin

  Poke(752,1);

  ClrScr;

  x:=5; y:=3; dx:=1; dy:=1;

  repeat

    x:=x+dx;

    y:=y+dy;

    GotoXY(x,y); Write('•');

    for i:=1 to 100 do;

    if (x=39) and (y=23) then ClrScr;

    GotoXY(x,y); Write(' ');

    if (x>38) or (x<1) then dx:=-dx;

    if (y>22) or (y<1) then dy:=-dy;

  until keypressed;

  Poke(752,0);

end.