Olivetti Logos 58

A calculator from Olivetti, 1973

The Logos 58 is a calculator Olivetti Logos 58, produced around 1973. It has a non-conventional triangular design. It was one of the first Olivetti calculators using electronics.

The logos 58 was part of a family of 5 models:
Logos 55, the basic model.
Logos 58 with the percentage button and two accumulators.
Logos 59 with an additional totalizer.
Logos 68 with square roots, square numbers, and with a capacity of 23 digits (compared to 16 for other models).
The Logos 70 is a programmable calculator; it could memorize a sequence till 256 operations.

There isn’t the display, so the result was printed only on the paper. It was considered more professional, because the numbers on display disappear, but the paper remains.

It has a very particular keyboard without subkeys. I uses magnetic switches, in combination with some magnets, on a little pendulum. When the magnet on the pendulum is near to the center of the magnetic switch, this is closed, so interrupting the contact between these two points for example. When the magnet is far from the center, the switch is open. You can see better on the video below.