Design is fine. History is mine. - Marcello Nizzoli, adding machines: 1/ Olivetti Summa 15, 1949. 2/ Olivetti Multisumma 20, 1964. 3/ Summa Prima 20, 1974. Slow calculators with no stored memory (
![Mechanical Calculator: 1963 Underwood-Olivetti Summa Prima 20 | To Type, Shoot Straight, and Speak the Truth... Mechanical Calculator: 1963 Underwood-Olivetti Summa Prima 20 | To Type, Shoot Straight, and Speak the Truth...](http://munk.org/typecast/wp-content/uploads/2015/08/IMAG1783.jpg)
Mechanical Calculator: 1963 Underwood-Olivetti Summa Prima 20 | To Type, Shoot Straight, and Speak the Truth...
![computer / electronics, computer, calculating machine Olivetti Summa 19, with integrated printer, design Ettore Sottsass and Hans von Klier, Italy, 1969, Additional-Rights-Clearences-Not Available Stock Photo - Alamy computer / electronics, computer, calculating machine Olivetti Summa 19, with integrated printer, design Ettore Sottsass and Hans von Klier, Italy, 1969, Additional-Rights-Clearences-Not Available Stock Photo - Alamy](https://c8.alamy.com/comp/FFN5YY/computer-electronics-computer-calculating-machine-olivetti-summa-19-FFN5YY.jpg)