Associazione Archivio Storico Olivetti - Olivetti "Tetractys" calculating machine

The Tetractys is a super-automatic writing calculator from 1956 designed by Natale Capellaro and designed by Marcello Nizzoli. It is capable of performing all four operations and has a memory. Released almost simultaneously with the Divisumma 24, it features some innovations: it has two totalizers that allow for high-speed calculations; it also allows for much more complex operations, such as "chain" multiplications or combined additions and multiplications.