Olivetti Tetractys 24
The abbreviation MC-24 is a series of electric calculating machines, automatic, with integrated print and register memory, produced by the Italian Olivetti , starting from 1956 . The mechanism was designed by Christmas Capellaro , while the body is due to Marcello Nizzoli . The most popular model and sold (they were produced 6 million units),
the Divisumma 24 as well as a revolution in the field of automatic
computers has also become an icon of industrial design Italian  , is part of the permanent collection of the Triennale Design Museum of Milan  , as well as being preserved in many museums dedicated to the design and science and technology and typewriters. The Divisumma 24 is also part of the permanent collection of the MoMA in New York 
The series consisted of three basic models: the Multisumma-24 (addition, subtraction and multiplication), the Divisumma-24 (also split) and Tetractys that, equipped with a dual totalizer and a number of additional features, represented the worldwide state of the art of mechanical calculation of those years. Were then made several special models, such as variants CR, equipped with trolleys tab for accounting needs. Among these there is also a "Elettrosumma 24 CR" no automatic multiplication.
The production of this class of machines, factories located in the ICO via Jervis, to Ivrea , continued until the '70s. The special versions, (MC24-CR), were initially produced in factories OMO, located in the village of San Bernardo Ivrea and subsequently translocated in the plants in Via Jervis, the assembly was piece-work individually, with average volumes of production of 50 units per day.
The most innovative aspect of these machines is the fact that the two top models were the first to have a calculator how to use almost completely analogous to that of the existing calculators: ability to perform the four operations, a single numeric keypad reduced (10 key) to set all the terms of the transaction and print the results.
Other Systems Related To Olivetti Tetractys 24:
This exhibit has a reference ID of CH33152. Please quote this reference ID in any communication with the Centre for Computing History.