Ah... the Casio Data Bank...!
...Reminds me of my days working for a (then) Fortune-400 computer manufacturer in the '80s. I had a DB and kept my phone numbers and schedule on it. If you didn't want to risk forgetting/losing your address book/scheduler, the Data Bank was (IMO) the best option available at the time. It could also be great fun, in certain circumstances.
I was a senior illustrator in the publications department at the aforementioned computer company and spent a fair amount of time attending Project Management Team meetings. (Before I got stuck doing that I felt that I was being paid an obscene amount of money to pursue my hobby; once I got roped into PMT meetings I felt that the amount I was paid was STILL an obscenity, just in the opposite direction... But I digress...)
The last item on the agenda of any PMT meeting is, of course, the scheduling of the next meeting. The documentation editor (who generally chaired the meetings, since everyone ALREADY hates editors) would study her Day Planner™ book and suggest, e.g., "How about Tuesday the 8th at 10 AM...?" The Writer would look at har Day Planner (denim, with leather corners) "That's fine." The Engineer would look at his Day Planner (larger, and with the leather cover) "Um... Yes, that works." The Marketing Rep would look at HIS Day Planner (the BIG leather one with the zipper around the side to hold in all the post-it notes sticking out from various pages that showed anyone who looked how busy and important he was) "Hmmmmm... No; I've got another meeting, then... Can we make it 11:00?" Everyone confirms 11:00...
...and looks over at the Dumb Artist.
Dumb Artist is so low on the social scale that he doesn't HAVE a Day Planner. He just has a pad of graph paper on which he's been doodling and occasionally scribbling cryptic notes throughout the meeting.
Dumb Artist looks at his wristwatch. *tap* *tap* "Tuesday at 11...?" *tap* *tap*... *tap* *tap* *tap* "Got it!"
It was always amusing to see the engineering and marketing reps of a computer company realize that the Dumb Artist was techie-er than they were. (Tackier, too, probably; but that's a whole 'nother issue!)
Granted that it's not particularly aesthetic-looking but, as a backup for contacts, etc., the Casio Data Bank was (and still is) a useful piece of kit.