@elb It's a National Cash Register Model 11-EN made in the early 1950s. NCR was better known for their ornate cash registers, but they also made electromechanical adding machines like this one. They apparently were also involved in manufacturing electromechanical Bombe computers during WWII to crack Enigma.

@kyle I grew up near Dayton, OH -- there's tons of NCR stuff near there, they were founded and then headquartered in Dayton for many, many years.

@Konqi It has the advantage of an electric motor to take the place of levers and cranks. It also seems easier because the UI is closer to modern calculators we are more familiar with, which makes sense, since electronic calculators started coming out a bit over a decade later.

@Konqi It underscores how much of what seems intuitive comes down to what you have already experienced. I bet in 30 years current calculator interfaces will seem hard and confusing, as people will be used to asking voice assistants instead.

@kyle @Konqi even on modern calculators just about everyone expects algebraic notation, so if I give someone my HP there is a near zero percent chance they can even add 2 + 2 since it uses RPN. The flipside of this coin is of course that after heavily using RPN for years I can barely use a regular calculator myself.