I have registered both of my humminbirds(859 and 899), now curious how to update them, or should I even do so? I have not down loaded humminbird PC because I have a MACBOOK PRO. Do I have to find a windows operating system to download humminbird pc? And then how do I link my graphs to my computer? And when I get it linked, will it automatically undate? Thanx in advance for any help!

