Many years later, I found another one on eBay:
Snazzy, isn't it? Not only is it a very early example of "landscape" control-panel design, it also has a peculiar display. The seven-segment vacuum fluorescent display is six-digit, but the calculator works with 12-digit numbers internally. The arrow key (bottom left of the keypad) shifts the display to show the other six digits of the answer. Not only that, but it also has a seven-segment font that has a half-height zero, with only four segments lit instead of the usual six.
So there we have it: the Casio Personal Mini, a quirky calculator.