<script type="text/javascript" 
        src="http://api.maps.yahoo.com/ajaxymap?v=3.8&appid=rlerdorf"></script>
<div id="jsmapContainer" style="height: 500px; width: 930px;"></div>

<form id="locF" onSubmit="return updateMap();">
  <label for="loc">Location:<label>
  <input type="text" name="loc" id="loc" size="80"/>
</form>

<script type="text/javascript">

var updateMap = function() {
  var loc = document.getElementById('loc').value;
  jsmap.drawZoomAndCenter(loc,7);
  return false;
};

var jsmap = new YMap('jsmapContainer');
jsmap.addZoomLong();
jsmap.addTypeControl();
jsmap.drawZoomAndCenter("Portland", 8);
</script>