function random_img(){

        var imgarray = new Array("j_c2","j_s2","j_cs4","j_xe6","sq_p4","sq_s4","core","surge","newwave","blast","fuse","kick","micra","crunch");
        // imgarray.length
        var dd = new Date();
        var sec = dd.getSeconds()

        var curimg = imgarray[sec % imgarray.length];
        
        // debug :-0
        // alert("<img src=\"top_img/" + curimg + "\">");
        document.write("<a href=\"tool/" + curimg + ".html\"><img src=\"images_top/img_" + curimg + ".jpg\" border=\"0\" width=\"225\"></a>");
}