function tick() {
  var hours, minutes, seconds, ap;
  var intHours, intMinutes, intSeconds;
  var today;

  today = new Date();

  intHours = today.getHours();
  intMinutes = today.getMinutes();
  intSeconds = today.getSeconds();

  switch(intHours){
       case 0:
           intHours = 12;
           hours = intHours+":";
           ap = "A.M.";
           break;
       case 12:
           hours = intHours+":";
           ap = "P.M.";
           break;
       case 24:
           intHours = 12;
           hours = intHours + ":";
           ap = "A.M.";
           break;
       default:    
           if (intHours > 12)
           {
             intHours = intHours - 12;
             hours = intHours + ":";
             ap = "P.M.";
             break;
           }
           if(intHours < 12)
           {
             hours = intHours + ":";
             ap = "A.M.";
           }
    }       
  
          
  if (intMinutes < 10) {
     minutes = "0"+intMinutes+":";
  } else {
     minutes = intMinutes+":";
  }

  if (intSeconds < 10) {
     seconds = "0"+intSeconds+" ";
  } else {
     seconds = intSeconds+" ";
  } 

  timeString = hours+minutes+seconds+ap;

  Clock.innerHTML = timeString;

  window.setTimeout("tick();", 100);
}

window.onload = tick;