var clockID = 0;
var clockHTMLId ;

function UpdateClock() {
   if(clockID) {
      clearTimeout(clockID);
      clockID  = 0;
   }

   var tDate = new Date();
   var hour = tDate.getHours();
   var minute = tDate.getMinutes();
  

    if(hour < 10)
        hour = "0" + hour;
        
    if(minute < 10)
        minute = "0" + minute;    

   document.getElementById(clockHTMLId).innerHTML =  " " 
                                   + hour + ":" 
                                   + minute ;
   
   clockID = setTimeout("UpdateClock()", 1000);
}
function StartClock(id) {
    clockHTMLId = id;
   clockID = setTimeout("UpdateClock()", 500);
}

function KillClock() {
   if(clockID) {
      clearTimeout(clockID);
      clockID  = 0;
   }
}