Monroe Mini Desk Calculator - Monroe Calculating Machine Co. ,1931.
Small and compact semi automatic adding and dividing calculator for desktop use only. The electro-mechanical machine is less noisy than the MonroMatic but also less versatile. It lacks a resetting option. Back to all zeros is done by subtracting the digits in the lower display from the keyboard.

Adder - Burroughs Adding Machine Company. St. Louis Missouri, 1940.
Powered by a strong motor this machine was widely used in offices for doing fast additions and calculations. The results were printed. Input from a ten digits keyboard in a 9x10 matrix. Extra function-keys to the right.

MonroMatic - Monroe Calculating Machine Company, 1949.
High Speed Adding Calculator for performing repeated adding tasks. This machine was partly programmable and made use of a small mechanical
memory for storing results.

Friden Automatic Calcualtor - Friden Calculating Machine Co. San Leandro.
This is the famous Model SW, boldy called 'The Thinking Machine of American Business' speaking with the manufacturer.
Model SW had an extra small calculator on the left side of the machine.

Facit Desktop Adder and Calculator - Advitaberg Facit Sweden, 1959.
This is the heavy Model CAI-13. The machine is based on the Odhner mechanism and must be operated from a rather awkward keyboard. The laborious keys prevent quick additions and calculations.

BOHN CONTEX-30 - Brdr. Carlsen A/S Birkerød, Denmark, 1964.
The electro-mechanical version of the Contex-10 also in a plastic cover. The ten digit keys can be operated smoothly for quick and instant additions and calculations. Swept from the market by cheap electronic calculators in 1965.

Victor Automtic Calculator - Victor Adding Machine Company, 1951.
The company produced electro-mechanical printing calculators until the early 70s. Victor still manufactures modern desktop calculators.
See Victor's nice historical website.

ADDO-X Desktop Calculator - AB Addo of Malmø, Sweden, 1963.
Modern electro-mechanical machine from Sweden. Addo merged with Facit in the late 50s.  The desktop machines could be operated smoothly while the results were printed on papertape.

Original Odhner AutoCalc - Odhner Göteborg, 1962.
Odhner tried very hard to survive in the 60s in the lengthening shadow of micro-electronics, chips and cheap calculators. Production of modern and pretty looking desktop electro-mechanical machines stopped in 1969.