function keyb_callback(ch)
        {
            var text = document.getElementById("txt_passwd");
			var val = text.value;
			
			
            switch(ch)
            {
                case "<<":
                var min=(val.charCodeAt(val.length - 1) == 10) ? 2 : 1;
                text.value = val.substr(0, val.length - min);
                break;

               	case "Enter":
                   //text.value += "\n";
                   break;

                case "DEL":
                    text.value = "";
                break;

               	default:
				if (val.length > 5) return false;
                text.value += ch;
            }
        }