The Olivetti Summa 15 adding machine

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:
www.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

great video! interesting machine

[@johnnycats5157]

the yellow joystick selector is awesome

[@GrumpyTim]

Typically for Olivetti that's a beautiful machine Jaap - I wonder why they dropped the multiplication counter when they did the Prima Summa 20, that seems like a brilliant feature. Great video, you should get plenty of views on this one as the Olivetti machines have a big following.

[@stephenfreeborn]

Yeah, I hadn’t seen that counter. You can sure pick out an Olivetti across the room.

[@franciscom.e.9780]

I have several Olivetti typewriters, but mechanical calculator… yet.

[@user-js1yn6jc2o]

Apologies for the unrelated comment! Regarding the Chasing the Lights method for LightsOut, there are pattern tables online which have the corresponding top buttons to press for 3x3,4x4,5x5,6x6,9x9, but I was wondering if it was possible to find a pattern table for 7x7 and 8x8, and how would I go about finding pattern tables for n size boards?

[@jaapsch2]

It is briefly explained on my Mathematics of Lights Out page in the section about the Pseudo-inverse. www.jaapsch.net/puzzles/lomath.htm#inverse On a blank board, see what light pattern you get on the last row if you press just one button on the top row and chase the lights down. Do this for each top row button. Build a matrix where the n-th matrix row is the light pattern corresponding to pressing the n-th button of the top row. Invert that matrix using standard Gaussian elimination (modulo 2) and then the rows of the resulting matrix is the pattern table you are looking for.