<script language="Javascript">
function send(value)
{
document.getElementById('code').value=value;
}
</script>

<form method="post" name="form_1">
<input type="radio" name="id" value="1" onClick="javascript:send(this.value)">
<input type="radio" name="id" value="2" onClick="javascript:send(this.value)">
</form>

<form method="post" name="form_2">
<input id="code" name="code" type="text">
</form>