纵向不间断滚动代码怎么写，看了孟老大的横向代码，可改不成纵向

<body>
<div style="width:543px;height:100px;overflow:hidden" onMouseOver="stop()" onMouseOut="start()"> 
<table width="543" border="0" cellspacing="0" cellpadding="0" id="scrollimg" height="21">
<tr> 
<td id="simg">
<TABLE width="543"  height=200 border="0" cellspacing="0" cellpadding="0" height="21">
<tr>
            <td ><a href="index.htm">AAAAA</a></td>
          </tr>
</TABLE>
</td>
<td id="simg1"></td>
</tr>
</table>
</div>
<SCRIPT LANGUAGE="JavaScript">
var tm=nullfunction newsScroll() 
{
if(scrollimg.parentNode.scrollTop!=(scrollimg.clientHeight/2))
scrollimg.parentNode.scrollTop++;
else
scrollimg.parentNode.scrollTop=0
}
window.onload=function() 
{
simg1.innerHTML=simg.innerHTML
tm=setInterval('newsScroll()',20) 
}
function stop()
{
clearInterval(tm)
}function start()
{
tm=setInterval('newsScroll()',20) 
}
</SCRIPT>
</body>