Uploaded October 2022 | Updated September 2026, 1 day ago

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The Olivetti Summa 15 adding machine was made in Italy in the 1950s. Its most unusual feature is the multi-function button that looks like a joystick.

For more information on this and other machines in my collection, please visit my website:
jaapsch.net/mechcalc

0:00 Introduction, history
1:06 Manual lever
1:36 Paper feed
1:53 Multi-function button
2:30 Entering numbers, clearing input
2:57 Addition
3:15 Totals and subtotals
4:05 Subtraction
4:25 Non-Add function
4:49 Button release
5:08 Repeat, multiplication
6:28 Ink ribbon
7:05 Negative totals
7:42 Serial number
8:11 Outro