Cellatron-R44SM, one of the last electro-mechanical calculators, made from 1960 on in the former DDR at the MERCEDES factory in Zella-Mehlis. Fully automatic 4 operations!
The Cellatron-R44SM is the last to be built electromechanical calculator at Zella-Mehlis, ex-DDR (German Democratic Republic). Designed by Christel Hamann, this fully automatic 4 operations calculator is based on the "proportional level" principle, which was invented and patented by Hamann. The first machines to use this feature were the famous EUKLID line, starting 1906 in Berlin.
The R44-SM has 3 memory registers. Multiplication can be done by "splitting" the large 20 column keyboard in two: the left 10 columns hold the multiplier, the right part the multiplicand. The machine was bought in 2007 at eBay, and repaired by F. Massen.