var running=false;
function startit(){
	if (running) {
		document.f.b.value="  go  ";
		return;
	}
	document.f.b.value="stop";
	q=Math.random();
	p=Math.floor(25*Math.random());
	if (q<.5) document.images[p].src="ball.gif"
	else document.images[p].src="white.gif";
	window.setTimeout("startit()",15);
}