Olivetti Divisumma 24 Calculating Machine (So Marked on Back)

Olivetti Divisumma 24 Calculating Machine (So Marked on Back)

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Established as a typewriter manufacturer in 1908, the Italian firm founded by engineer Camillo Olivetti (1868–1943) began manufacturing a calculating machine in 1940. After World War II, it introduced a ten-key printing machine capable of division, the Divisumma 14. This is a later version of that machine, the Divisumma 24, which was introduced in 1956. Like many Olivetti products, these adding machines reflect the style of artist and industrial designer Marcello Nizzoli and have received attention for that reason. This example was manufactured after Olivetti acquired the Underwood Typewriter Company in 1959.
The machine has a gray metal case with a black lid. The yellow keyboard has a block of nine white number keys. Below these are three black keys with white dots for setting single, double, and triple zeros. To the right are two sets of four keys. Four of these are green, and relate to operations in the green register. The other four are black, and relate to operations in the black register (keys of one color are not grouped).
To the left of the numeral keys are the backspace key and the keyboard clearing key. Below them is the thumb add bar. Left of these are two levers with green knobs. One, marked A, predetermines automatic or non-automatic printing of the product. The other, marked R, is a repeat key. Further keys are to the left of these. The column indicator is above the keyboard.
The printing mechanism toward the back includes four digit wheels used to set dates, 13 digit wheels for numbers, and two type wheels right of the digit-wheels to print symbols. Totals are printed in red. The serrated plastic edge helps to tear the paper tape.
A mark on the top of the machine reads: underwood * olivetti. A mark on the back reads: Divisumma 24 Olivetti (/) MADE IN ITALY FABRIQUE EN ITALIE. A plate attached to the bottom has the serial number: 2D014738.
The machine also has a gray plastic cover, three paper tapes and two cords stored. The tapes are 8.8 cm. (3-1/2”) wide.
Compare 1979.0932.01.
The Kansas physician Richard L. Sutton Jr. reported when he donated the object to the Smithsonian Institution in 1979 that he found it “a meritorious machine, to which I have been strongly attached emotionally.”
S. Kicherer, Olivetti: A Study of the Corporate Management of Design, New York: Rizzoli Inc, 1990.
N. Shapira, Design Process Olivetti 1908–1978, [Ivrea, Italy]: Olivetti, 1979, pp. 56–57.
Olivetti, Instructions for the Operation of Tetractys Printing Calculator, 1958. (1979.0854.02).
Accession file.
Currently not on view
Object Name
calculating machine
date made
place made
Physical Description
plastic (overall material)
paper (overall material)
rubber (overall material)
metal (overall material)
overall: 24.5 cm x 24.5 cm x 42 cm; 9 21/32 in x 9 21/32 in x 16 17/32 in
ID Number
maker number
accession number
catalog number
Credit Line
Gift of Richard L. Sutton, Jr.
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History
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Só para corrigir uma injustiça. Citou o nome do desenhista da carroceria Marcello Nizzoli, mas não citou o nome mais importante. NATALE CAPELLARO foi quem idealizou e projetou esta calculadora. Natale Capellaro, gênio autodidata. Procure conhecer quem foi NATALE CAPELLARO e vai se surpreender.
I was a technician like Sandy-but in Hamburg in the mid 1950's. When the Divisumma came out fellows in the office where sent to Ivrea to be taught . Working on the machines required precise movement of the hand and wrist plus knowing the orderly sequence of the parts . The machine would tell you if you were wrong. In 1956 I immigrated to San Francisco and worked for Olivetti . It is interesting to note that by the late 60's our profession as office machine Mechanics was gone-the transistor took over. I saw scrap dealers taking pick-up truckloads full of calculators to the dump in South San Francisco.
This is a D24. I used to repair them in the 1970s and 1980s. It is a marvel of mechanical engineering to have all those parts to be in the correct place at the correct time.
I agree, the machine shown is an Olivetti Tetractys.
I'll bore you with a little Olivetti history. I was a service technician for Olivetti Canada working in S. Ontario east of Toronto in the late 1960's and through the 70's. There were classrooms in High Schools with 20 to 35 D-24s as well as offices with many of them. Generally they were very reliable as long as we kept up the "inspections" as they were known. You would go to an office on as regular as possible a basis - usually every 3 or 4 months - and service the machines, which included typewriters as well as calculators and adding machines. Keeping the registers lubricated with light oil was important. If the register became too dry the result would be "split totals" because the register directly controlled the print wheels through the print racks. The first total would be less than the correct answer and if you pressed total again you got the remainder of the sum. If the operator didn't know to look for this they believed the machine had a serious problem, so we trained many of them what to do to look for "split totals". A genuinely serious problem was a broken symbol rack where you always got the same symbol no matter what the operation was and which meant removing the motor and packing in asbestos to protect other parts while you silver soldered the print rack. Yet another fault was a worn out fibre gear which involved some disassembly. The company came up with a split gear which made this job much faster. The latter two problems were shop jobs which meant that you stocked several loaners to take to the customer while their machine was in shop. Quite different from electronic machines where the most serious problems mean you switch a circuit board or scrap the machine. In Olivetti's effort to come up with faster mechanical machines to compete with the early electronic calculators, the eventual replacement for the D-24 was the fancier but no faster D-26, and after that the Logos 27. The less said about it the better. It was so fast that mechanical parts simply could not follow the cams unless everything was perfect. The result was jam, followed by Jam, followed by JAM! I still have one of those boat anchors. I don't believe the Logos 27 was even sold in the U.S. They probably took a look at the 50 lb monster and said "Naaww, I don't think so!" The best thing about the Logos 27 was that it finally persuaded Olivetti to give up on mechanical calculators and their own electronic machines soon replaced it.
I would just like to confirm Mark Gluskers' observation. It is a Tetractys 24. Not nearly as popular as the Divi 24 because of the duel adding machine feature that would let the operator do foot and crossfoot additions.
"This is actually an Olivetti Tetractys, not a Divisumma. The distinction is clear by the extra keys on the keyboard. The enclosure is exactly the same as the Divisumma, so it appears your machine has had the case swapped with a Divisumma (thus the "Divisumma 24 " on the label at the rear of the case)."

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