function start() {
uhrzeit();
window.setInterval("uhrzeit()", 1000);
}

function uhrzeit() {
// Array für dynamische und statische Darstellungen
DayName = new Array("Sonntag","Montag","Dienstag","Mittwoch","Donnerstag","Freitag","Samstag");
var SystemDate = new Date();
 var Day = SystemDate.getDate();
 var MonthNow = SystemDate.getMonth() + 1;
 var YearNow = SystemDate.getYear() % 100;
 var HoursNow = SystemDate.getHours();
 var MinuteNow = SystemDate.getMinutes();
 var Seconds = SystemDate.getSeconds();
 var DayOfWeek = SystemDate.getDay();
 DOW = SystemDate.getDay();

 // für zweistellige Anzeige
 var firstDay  = ((Day < 10) ? "0" : "");
 var firstMonth  = ((MonthNow < 10) ? ".0" : ".");
 var firstHour  = ((HoursNow < 10) ? "0" : "");
 var firstMinute  = ((MinuteNow < 10) ? ":0" : ":");
 var firstSecond  = ((Seconds < 10) ? ":0" : ":");
 var firstYear  = (( YearNow < 10) ? "0" : "");

 // aktuelles Datum
 DateString= firstDay + Day + firstMonth + MonthNow  + "." + firstYear+ YearNow;
 // aktuelle Zeit
 TimeString= firstHour + HoursNow + firstMinute + MinuteNow + firstSecond + Seconds;
 // Wochentag Datum Zeit
WholeString = DayName[DayOfWeek] + " " + DateString  + " " +TimeString;
var uhrzeit = document.createTextNode(WholeString);
document.getElementById("uhrzeit").replaceChild(uhrzeit,document.getElementById("uhrzeit").firstChild);
}