Ti passo il codice:

codice:
<HTML>
<HEAD>
<SCRIPT>
<!--
I=0;

function roller()
{
I=I+1;
document.modulo.frase.value=I;
clearInterval(timerID);
setTimeout("timerID=setInterval('roller()',200)",400);
}
//-->
</SCRIPT>
</HEAD>
<BODY onLoad="timerID=setInterval('roller()',200)">
<FORM NAME="modulo">
<INPUT TYPE="text" SIZE="50" NAME="frase">
<INPUT TYPE="button" VALUE="Interrompi" onClick="clearInterval(timerID)"> </FORM>
</BODY>
</HTML>