The Olivetti Summa 15 is a manual adding listing machine with a 10-key keyboard. It has an 11-digit register, and allows 10 digits of input. Four function buttons have been combined into a unique four-way button reminiscent of a joystick. This button can be flicked with the thumb of the right hand just before you pull the lever. Depending on which direction the button is moved, a different function is performed - Total (∗ up), Subtotal (⋄ down), Subtract (- right), or Non-add (⊲ left). There is a small tab to the right of the keyboard which is used to release the four-way button if it was accidentally pushed in the wrong direction.
There is cover that is easily removed, giving access to the ink ribbon. The machine takes a standard half-inch wide two-colour ink ribbon. The serial number is only found inside, etched into the metal base of the mechanism. The number of this machine is 366,286.
Below is a video I made that demonstrates the Olivetti Summa 15.
The company was founded by Camillo Olivetti in 1908 in Ivrea, a village near Turin, Italy. Initially they made typewriters, but started on adding machines in 1934. Camillo's son, Adriano Olivetti, became chairman in 1938 and was responsible for the company's focus on innovation and design, and for the expansion of its international subsidiaries and sales. In 1959 it even acquired the major american typewriter company Underwood.
Even as Olivetti was making mechanical calculators and adding machines, it was also researching electronics, making Italy's first commercial electronic computer, the Elea 9003 in 1959. After the death of Adriano Olivetti in 1960, Olivetti's lack of leadership and the cost of the Underwood takeover caused financial difficulties, and the electronics division was spun off to a separate company and sold to General Electric.
In the 1970s a renewed focus on small electronics and transition away from purely mechanical machines allowed the company to survive, but the heavy cost of this transition again put the company in financial difficulties. Carlo De Benedetti bought a stake in the company in 1978 and managed the company through its recovery. They developed new electronic products, including in 1982 the first Olivetti personal computer. They did not leave mechanics behind completely, but used their expertise in the development of printers, fax machines, and photocopiers. In the 90s they moved into the telecommunications business, buying the majority of Telecom Italia in 1999, and eventually merging with it in 2003. Currently Olivetti exists as a subsidi
Olivetti's models were generally given successive model numbers, though it seems that some model numbers were skipped or never released, and some of the later model numbers were released out of order. They were also often given names depending on the general type of machine, occasionally with a suffix of a few letters or a word to describe the exact variant.
|Summa||:||Manual; addition, subtraction|
|Elettrosumma||:||Electric; addition, subtraction|
|Multisumma||:||Electric; addition, subtraction, multiplication|
|Divisumma||:||Electric; addition, subtraction, automatic multiplication, automatic division|
|GT||:||Grand Total, i.e. an additional totaliser register|
|CR||:||Carriage instead of a paper roll, often used for bookkeeping|
|Duplex||:||Two main registers|
|R or NR||:||Reduced capacity|
Below is a partial list of models, taken from Rechner Lexikon. The production years are only approximate.
|Summa MC 4||10×11||1940-19??||The first adding machine Olivetti released|
|Elettrosumma MC 4||10×11||1940-19??|
|Multisumma MC 4||10×11||1941-1947||Multiplier keys|
|Multisumma 14||10×11||1948-1954?||Multiplier keys|
|Divisumma 14||10×11||1948-1957||Olivetti's first 4-function calculator|
|Divisumma 14 CR||10×11||1948-19??|
|Summa Prima 20||10×11||1960-1974||Manual|
|Summa Quanta 20||10×11||1961?-197?||Electric|
|Summa Quanta 20R||7×8||1968-197?||Electric|
|Elettrosumma 20||10×11||1963?-19??||Similar to Summa Quanta but rearranged buttons|
|Multisumma 20||10×11||1964-19??||First with fully automatic multiplication instead of multiplier keys|
|Elettrosumma 22 Duplex||12×13||1954-1966|
|Elettrosumma 24 Duplex CR||12×13||1954-19??|
|Multisumma 24 GT||12×13|
|Divisumma 24 CR||12×13||1960-1973|
|Divisumma 24 GT||12×13||1962-1973|
|Tetractys 24||12×13||1955-19??||Like Divisumma?|
|Tetractys 24 CR||12×13||1956-19??|
|Elettrosumma 23||12×13||1966-19??||Faster improved version of model 20|
|Multisumma 26 GT||12×13||1967-19??|
|Divisumma 26 GT||12×13||1967-19??|
|Logos 27-2||15×15||1968-1970||Has an extra memory register and two totaliser registers.|
Here is a selection of short articles about Olivetti's calculators.
Long article about Olivetti's design
(1961-11 Industrial Design)
This is a selection of the Olivetti patents related to calculators.
|Patent||Filing date||Published date||Name||Description|
|CH 209,884||04-03-1939||01-08-1940||Ing. C. Olivetti & C.; Riccardo Levi||Quiet printing mechanism
See also: GB 514,237
|CH 210,231||04-03-1939||02-09-1940||Ing. C. Olivetti & C.||Ten-key input with display|
|CH 215,175||14-06-1940||01-09-1941||Ing. C. Olivetti & C.||Multiplier keys|
|CH 223,101||31-10-1941||16-11-1942||Ing. C. Olivetti & C.||Direct total printing|
|GB 662,118||31-08-1948||28-11-1951||Ing. C. Olivetti & C.; Natale Capellaro; Teresio Gassino||Four-way button
See also: US 2,545,649
|CH 276,455||29-01-1948||01-10-1951||Ing. C. Olivetti & C.; Natale Capellaro||Adding listing machine`with multiplication
See also: AT 172,028 B; DE 939,114; US 2,603,414
|FR 988,266||14-06-1949||24-08-1951||Ing. C. Olivetti & C.||Case suspension|
|FR 1,020,955||26-06-1950||12-02-1953||Ing. C. Olivetti & C.||Ribbon reversal|
|CH 278,640||17-03-1950||16-02-1952||Ing. C. Olivetti & C.; Natale Capellaro||Automatic division
See also: AT 173,209 B; DE 915,510; GB 700,000; US 2,754,052
|DE 1,042,275||21-07-1953||30-10-1958||Ing. C. Olivetti & C.||Duplex calculator keyboard|
|CH 314,044||30-07-1953||14-07-1956||Ing. C. Olivetti & C.; Natale Capellaro||Duplex calculator|
|CH 346,049||23-09-1958||15-06-1960||Ing. C. Olivetti & C.; Natale Capellaro; Teresio Gassino||Shortcut multiplication
See also: BE 571,491; DE 1,125,209; US 2,952,406
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