Phím di chuyển

uses crt;
var
  ch: char;
  x,y,m: byte;
begin
  clrscr;
  x:=10;
  y:=10;
  {x=80;y=25}
  repeat
    begin
      clrscr;
      gotoxy(x,y);
      write('*');
      {gotoxy(75,25);write(x:2,',',y:2);}
      ch:=readkey;
      if ord(ch)=72 then begin y:=y-1; if y<1  then y:=25; end;
      if ord(ch)=80 then begin y:=y+1; if y>25 then y:=1;  end;
      if ord(ch)=75 then begin x:=x-1; if x<1  then x:=80; end;
      if ord(ch)=77 then begin x:=x+1; if x>80 then x:=1;  end;
      {writeln(ch,' = ',ord(ch));}
    end;
  until ord(ch)=27;
end.