[Synthisternation]

Why is it that you can only store your edited patches on ROM A-D? Why is there all this left over "empty" room from RAM T-Z? I don't want to overwrite anything on the synth. Is there a way to save your sounds on ROM? My synth didn't come with a manual. Only a quick start guide. If you don't want to explain such simple questions, tell me where I can get a more comprehensive manual?