codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="it">

<head>

<title>sssssssssssss</title>

<style type="text/css">
body{ text-align: center; margin-top: 100px;"}
</style>

</head>

<body style="background-color:silver;">

<form action="">
    <input type="text" name="T1" size="20" value="2.htm" />
    <input type="button" value="Invia" onclick="parent.pippo.location.href = this.form.T1.value" />
</form>

<p align="center"></p>
<p align="center"></p>
<p align="center"></p>

<IFRAME
       src="1.htm" 
       height="300" 
       width="80%" 
       scrolling="No" 
       frameborder="0" 
       marginwidth="50" 
       marginheight="100"
       name="pippo"> 
</iFRAME>

</body>

</html>