// JavaScript Document
var current = 1;

function move( daVez )
{
current += daVez;
if ( current < 1 ) current = 2;
if ( current > 2 ) current = 1;
mostra( current );
}

function mostra( prox )
{
current = prox;
for ( var dnum = 1; dnum <= 2; ++dnum )
{
var dv = document.getElementById("banalt"+dnum);
dv.style.display = ( dnum == prox ? 'block' : 'none' );
}
}