1960 mechanical calculator by Olivetti
The Tetractys-24CR was one of the most complex electro-mechanical machines built by Olivetti in the 1960's. The (non functional) machine exposed has a large carriage and a programming wheel, and was used as a booking machine. It has two adding registers and one memory register. Contents from one register can be transfered to the other, and the machine makes all 4 operations in a fully automatic manner. Calculating speed is 250 cycles per minute.
A very interesting article can be found by googling for "oeil numérique Tetractys 24-CR".
This object is exposed at the Computarium of the LCD.