I assume the 3 Blackjacks have the same chip, but I've only looked at the D3. You may not be able to get into the handheld one easily- I had to bend the Radio Shack blackjack calculator's case to get it open.
Found my D-2... This thing is very well made, metal screw thread (instead of just screwing into plastic), well made buttons like ones from an old calculator (which it doubles as)... This thing was meant to be _used_...
The chip in mine is Rockwell, labelled: A4821CA (date code 7721).
