Electromechanical calculating machines from the 1960's
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Rotary calculators
 Badenia VA-17
Badenia VARE-17
Bohn Contex 55
Cellatron R44SM
Diehl DSR-18
Diehl VSR-18
Facit CA1-13
Friden SBT
Friden SVE
Friden SRW
Friden SRQ
Friden RSR
Hamann 505
Madas 20 BTG
Marchant ABL
Marchant SKA DeciMagic
Marchant Tenkeymatic
Monroe IQ-213
Olympia RA-16
Soemtron 214

Printing calculators

Mechanisms

Glossary

Other calculating devices

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Acknowledgements

Wanted

  
Friden SRW        
 
Manufacturer
   Friden Inc.
San Leandro, California, USA
 
Mechanism
   stepped drum
 
Capacity
   10 x 11 x 20
 
Years produced
    
 
Price when new
    
 
Size (W x D x H)
   in.
cm.
 
Weight
   lb. oz. (kg)
 
Features
   automatic square root
  click on photo to enlarge    
         
This is the first mechanical calculator to automatically extract square roots at the push of a single button. It had the longest production run if the three Friden square root machines: total production was approximately 10,000 units between 1952 and 1963. It used a mechanical implementation of the “Rule of Fives” to calculate the root. The appropriate button at the bottom of the keyboard needed to be pressed. (MMM, Fridenites)