Obviously specific software would have to be written to take advantage of this, but couldn't a 4MB or 8MB chip be installed and then have a switch installed to swap out the page sets?
I'll just explain the 4MB for simplicity. You install the 4MB chip and have the highest pin tied to a physical switch that is default on. Then you load the OS and certificate and boot sector into the 80 - FF range, which the calculator just sees as 00 - 7F. So like this, the calculator would be completely normal. But now, you flip the switch and have access to the first page set which could be used for archive purposes. Obviously things would have to remain in RAM when the pages are swapped, but I don't really see any problems with this idea. You could even make a boot page and page 0 so that if a ram clear occurs, it would give a message to flip the switch.
