A Programma 101.
The Programma 101, also known as Perottina, was the first commercial "desktop computer". Produced by Italian manufacturer Olivetti, based in Piedmont, and invented by the Italian engineer Pier Giorgio Perotto. 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 ($23,000 if adjusted to 2011). About 44,000 units were sold, primarily in the US.
It is usually called a printing programmable calculator or desktop calculator because three years later the Hewlett-Packard 9100A, a model that took inspiration from the P101, was advertised by HP as a "portable calculator", in order to be able to overcome the fears of computers and be able to sell it to corporations without passing through the corporate computer department. The concept of "stored program", however, allows the Programma 101 to be considered a true computer.
The Programma 101 was able to calculate the basic four arithmetic functions (addition, subtraction, multiplication, and division), plus square root, absolute value, and fractional part. Also clear, transfer, exchange, and stop for input. There were 16 jump instructions and 16 conditional jump instructions. It's the conditional jump instructions that help lay claim to "computer" (a state machine) rather than "calculator" (a simple enumerator of instructions). 32 label statements were available as destinations for the 32 jump instructions and/or the four start keys (V, W, Y, Z).
Its memory consisted of 10 registers: three for operations (M, A, R); two for storage (B, C); three for storage and/or program (assignable as needed: D, E, F); and two for program only (p1, p2). Five of the registers (B, C, D, E, F) could be subdivided into half-registers, containing an 11-digit number with sign and decimal point. When used for programming, each full register stored 24 instructions. So its most distinctive structural difference from later computers was that its instruction space and its data space were functionally separate.
It printed programs and results onto a roll of paper tape, similar to calculator or cash register paper.
Programming was similar to assembly language, but simpler, as there were fewer options. It directed the exchange between memory registers and calculation registers, and operations in the registers.
The stored programs could be recorded onto plastic cards approximately 10 cm × 20 cm that had a magnetic coating on one side and an area for writing on the other. Each card could be recorded on two stripes, enabling it to store two programs. All ten registers were stored on the card, allowing programs to use up to ten stored 11-digit constants.
The program to calculate logarithms occupied both stripes of one magnetic card.
All computation was handled by discrete devices (transistors and diodes mounted on phenolic resin circuit card assemblies), as there were no microprocessors, and integrated circuits were in their infancy. It used an acoustical delay line memory with metal wires as a data storage device. Magnetostriction transducers inside an electromagnet attached to either side of the end of the wire. Data bits entering the magnets caused the transducer to contract or expand (based on binary value) and to twist the end of the wire. The resulting torsional wave moved down the wire. A piezoelectric transducer converted the bits into an electronic signal that was then amplified and sent back to the beginning with a delay time of 2.2 milliseconds. Typically, many bits would be in transit through the delay, and the computer selected them by counting and comparing to a master clock to find the particular bit it required. Delay line memory was far less expensive and far more reliable per bit than flip-flops made from vacuum tubes, and yet far faster than latching relays. This "serial memory" design would later be implemented as mechanical magnetic drum memory in computers and as solid-state shift-register memory in early Visual Display Units.
Design and ergonomy
Olivetti was famous for its attention to both engineering and design aspects, as the permanent collection at the Museum of Modern Art testify, and the Programma 101 was another example of this attention. Engineering wise, the team worked hard to deliver a very simple product, something that anyone could use. To take care of the ergonomics and aesthetics of a product that didn't 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.
Interaction design and usability
One of the direct results of the Programma 101 team focus on human-centered objectives was the invention of the programmable magnetic card, a revolutionary item for that time allowing anyone to just insert it and execute any program in a few seconds.
It was a very portable and effective solution: a small magnetic strip with a program memorized in it and a space on the other side to write the description. The program was loaded just by inserting the card at the top, and when the card came out at the bottom, it was aligned perfectly with the V, W, Y, Z keys in a way that the author could have written on the card the labels for these buttons, to make the user aware of their new function.
It 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, and earned Bellini the Compasso d'Oro Industrial Design Award.
Developed between 1962 and 1964, it was saved from the sale of the computer division to GE thanks to an employee who one night changed the internal categorization of the product from "computer" to "calculator", leaving the small team within Olivetti and creating some awkward situations in the office, since the building except that office was then owned by GE.
The Programma 101 was launched at the 1964 New York World's Fair, attracting major interest. 40,000 units were sold; 90% of them in the United States where the sale price was $3,200 (increasing to about $3,500 in 1968.)
Hewlett-Packard was ordered to pay about $900,000 ($6.74 million in present day terms ) in royalties to Olivetti after copying some of the solutions adopted in Programma 101, like the magnetic card and the architecture, in the HP 9100.
By Apollo 11 we had a desktop computer, sort of, kind of, called an Olivetti Programma 101. It was a kind of supercalculator. It was probably a foot and a half square, and about maybe eight inches tall. It would add, subtract, multiply, and divide, but it would remember a sequence of these things, and it would record that sequence on a magnetic card, a magnetic strip that was about a foot long and two inches wide. So you could write a sequence, a programming sequence, and load it in there, and the if you would — the Lunar Module high-gain antenna was not very smart, it didn't know where Earth was. [...] We would have to run four separate programs on this Programma 101 [...]—David W. Whittle, 2006 
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|Wikimedia Commons has media related to Olivetti Programma 101.|
- A simulator of the Olivetti Programma 101.
- "General Reference Manual". Old Calculator Museum.
- Olivetti Programma 101 Emulator/Trainer, RetroWiki.es
- A Technical Description of the Olivetti Programma 101 with a picture gallery, by Alfredo Logioia.