Programma 101

The Olivetti Programma 101, also known as Perottina or P101, is one of the first "all in one" commercial desktop programmable calculators, although not the first. Produced by Italian manufacturer Olivetti, based in Ivrea, Piedmont, and invented by the Italian engineer Pier Giorgio Perotto, the P101 used many features of large computers of that period. It was launched at the 1964 New York World's Fair; volume production started in 1965. A futuristic design for its time, the Programma 101 was priced at $3,200 (equivalent to $32,700 in 2025). About 44,000 units were sold, primarily in the US.

It is usually called a printing programmable calculator or desktop calculator because its arithmetic instructions correspond to calculator operations, while its instruction set (which allows for conditional jump) and structure qualifies it as a stored-program computer.

The Programma 101 was designed by Olivetti engineer Pier Giorgio Perotto in Ivrea. The styling, attributed to Marco Zanuso but in reality by Mario Bellini, was ergonomical and innovative for the time. Some of the design was based on a 1961 Olivetti computer co-developed by Federico Faggin that served as a model for the programmable calculator.

The computational hardware consisted of standard (for its time) discrete devices (transistors, diodes, resistors and capacitors mounted on phenolic resin circuit card assemblies). The design predated microprocessors, and no integrated circuits were used since they were in their infancy.

A total of 240 bytes of information were electrically stored in magnetostrictive delay-line memory, which had a cycle time of 2.2 milliseconds.

The focus of the engineering team was to deliver a very simple product, something that anyone could use. To take care of the ergonomics and aesthetics of a product that did not exist before, Roberto Olivetti called Mario Bellini, a young Italian architect:

I remember that one day I received a call from Roberto Olivetti: "I want to see you for a complex project I'm building". It involved the design not of a box containing mechanisms and stamped circuits, but a personal object, something that had to live with a person, a person with his chair sitting at a table or desktop and that had to start a relationship of comprehension, of interaction, something quite new because before then computers were as big as a wardrobe. With a wardrobe we don't have any relationship: in fact the most beautiful wardrobes disappear in the wall. But this wasn't a wardrobe or a box, this was a machine designed to be part of your personal entourage.

— Mario Bellini, 2011, "Programma 101 — memory of the future", cit.