Olivetti Summa Prima 20

Olivetti Summa Prima 20 mechanical adding machine . Made in Italy, around 1960 , original design by Marcello Nizzoli in 1949. The keyboard includes special keys for "10" and "11", for working in pounds, shillings and old pence. Prints the answers on to a small roll of paper using black ink for addition and red ink for subtraction

This 1960s machine operates in either Sterling or decimal currency, as selected by a small lever on the under side of the base.

These machines were supplied as replacements for Sterling add-list machines during Australia's conversion to decimal currency in 1966. Most of them were retired in the early 1970s, after relatively little use, in favour of the new electronic calculators. They can still be found in large numbers, and are generally still in good working order.

12cm high / 23cm wide / 38cm deep / 4.1 kilograms