uses dos, graph, crt;

procedure PrintTime;

  function IntToStr(I: Longint): string;
  var s: string;
  begin
    Str(I, s);
    if length(s) < 2 then s := '0' + s;
    IntToStr := s;
  end;

var
  hr, min, sec, hnd: word;
  s: string;
begin
  clearviewport;
  gettime(hr, min, sec, hnd);
  s := inttostr(hr) + ':' + inttostr(min) + ':' +
       inttostr(sec) + '.' + inttostr(hnd);
  outtextxy(getmaxx div 4, 5 + textheight('W'), s);
end;
var
  Driver, Mode: integer;
  Err: integer;

begin
  initgraph(Driver, Mode, '');
  Err := graphresult;
  if Err = grOk then
  begin
    setviewport(0, 0, getmaxx div 2, 10 + textheight('W'), clipon);
    settextjustify(centertext, centertext);
    repeat
      PrintTime;
      if keypressed then
      case readkey of
        #27: break;
      end;
      delay(50);
    until false;
    closegraph;
  end
  else writeln('error on InitGraph: ', grapherrormsg(Err));
end.