var show_time=false;
  var timerID=null;

  function stop(){
    if (show_time){
        clearTimeout(timerID);
        document.clock.time.value=" ";
    }
    show_time=false;
  }

  function start(form){
    var today=new Date();
    var display_value = today.getHours()
    if(today.getMinutes() < 10){
        display_value+=":0" + today.getMinutes();
    }
    else{
        display_value+=":" + today.getMinutes();
    }
    if (today.getSeconds() < 10){
        display_value+=":0" + today.getSeconds();
    }
    else{
        display_value+=":" + today.getSeconds();
    }
        document.clock.time.value=display_value;
        timerID=setTimeout("start()",100);
        show_time=true;
  }