//События, +=, -=, демонстрация работы таймера System.Timers.Timer
uses System;

var
  Timer: System.Timers.Timer;
  x: integer;
  exit: boolean;

procedure OnTimer2(sender: object; e: System.Timers.ElapsedEventArgs);
begin
  Writeln(x);
  x := x + 1;
  exit := x >= 10;
end;

procedure OnTimer1(sender: object; e: System.Timers.ElapsedEventArgs);
begin
  Writeln(e.SignalTime);
  x := x + 1;
  if x >= 5 then begin
    Timer.Elapsed -= OnTimer1;
    Timer.Elapsed += OnTimer2;
  end;
end;

begin
  Exit := false;
  Timer := System.Timers.Timer.Create(1000);
  Timer.Elapsed += OnTimer1;
  Timer.Start;
  while not exit do 
    Sleep(Round(Timer.Interval));
end.