mattew,

This was discussed recently so check recent post's. 128k of data store is not really that big an issue. You will have to determine a strategy for data storage and retrieval and this will set you "granularity" that is the size of a window into your data store.

It is not un-typical to keep a "common area" of data store always available (say from 0-7FFFH) and then bank additional memory in to the top area (8000-FFFFH).

There is a note that is somewhat Dallas specific but you might be interested:

banking ds320

regards,
p