Designed by Curt Karzstark while held in Buchenwald concentration camp. This wonderful cross between a dalek and pepper mill is one of the the most powerfully compact mechanical computers in the world!
This four-banger pepper mill can also perform square root calculation with some finessing. To add two numbers together, each must be entered on the digit setting sliders and sent to the result counter around the top by moving the crank clockwise for one full rotation. Subtraction is as easy as pulling out the crank until the red indicator appears. The CURTA performs subtraction using nine’s complement arithmetic. Multiplication and division are possible through successive additions and subtractions and use of the powers of ten carriage, which is the top knurled portion.
If I had one I would have to take it apart and see how it works. Thankfully this video shows me that ‘I know nothing!’… of how CURTA works.
CURTA design and theory.
This all comes via RetroTachtacular – wonder from days of yore.