var img_dir = "images/";
var ddata1,ddata2 ,ddata3;

function cchange( ddata1 , ddata2 ){
	if( ddata2 ==  "on" ){
	ddata3 = img_dir + ddata1 + "_on.gif";
		document.images[ddata1].src = ddata3;
	}
	else{
		document.images[ddata1].src = img_dir + ddata1 + ".gif";
	}
}

function preimg(){
var loadcomp = false;
	var preload = new Array();
	for(i = 0 ; i < preloadlist.length ; i++) {
		preload[i] = new Image();
		preload[i].src = preloadlist[i];
	}
	loadcomp = true;
}

var preloadlist = new Array
	(
	'images/button01.gif',
	'images/button01_on.gif'
	
	);
preimg();