Addiator Arithma
Brunsviga 13RK
Calculator "Superautomat SASL"
Mechanical calculator MADAS
Mellita, Model V/16
Original PRODUX calculator
XxX calculator

Original PRODUX calculator
PRODUX, 1935
Otto Meuter was the inventor of the ADDIATOR calculator. Because he had no money, he joined Carl Kuebler, a businessman. C.Kuebler founded the ADDIATOR company in Berlin / Germany in 1920 and O.Meuter got a profit of 50 pence for each calculator produced. 1928 O.Meuter's calculators became successful under the name PRODUX. After WW-II his company split: In West-Germany PRODUX production continued and under the East-German system RECORD calculators were produced until 1988.
Can only add or subtract. Numbers are entered with the vertical sliders (one set for positive numbers and one for negative numbers) using the accompanying stylus. The result appears in the circular windows in the middle.