|Canon Multi 8. Memory is shown in upper display.|
It's strange that this feature never caught on, because it's pretty useful. A switch next to the display changes what it does. In memory mode, whatever is stored in the memory is shown on the upper display. Process mode shows the total of your current calculation, which is especially handy because you can always know when you haven't made a huge mistake. Single mode deactivates the upper display so it's not very interesting.
Buttons are standard fare, but that's not to say they're bad. Far from it. They feel fine and responsive, and their colors fit well with the brushed aluminum front plate. The only issue I have is that the clear memory and cl/c buttons are very close together, so it's easy to accidentally clear the memory when you're starting a new calculation.
It runs on three AAA batteries, but there's also a port at the bottom to plug it into the wall with a 4.5 volt adapter.