Odhner
Odhner specialised in pinwheel mechanical calculators, which were invented by Willgodt T. Odhner in St. Peterburg, Russia, in 1874 (a calculator on similar principles was invented independently 2 years earlier by Frank Baldwin in the USA, but the Odhner was the successful design). Following the Russian Revolution of 1917 and the nationalisation of the factory there, production moved to Sweden and the name "Original Odhner" was adopted.
The Odhner was very successful, thousands were manufactured into the early 1970s, and the design was copied and adapted by many companies. The company did not make the switch to electronic calculators.
Kevin Odhner (yes, related to the inventor) has a fascinating history of Odhner mechanical calculators at http://mywebpages.comcast.net/wtodhner/
An example of an Odhner calculator
