Walther EMKD


The EMKD is -for its time-  a complicated high-end pinwheel machine.  As stated by  www.boelters.de/Rechenmaschinen  it once was the flagship of Walther calculators.  

It does not fit well in my mechanical collection which focuses on machines used in the 60’s and early 70’.  However, when I saw it for sale I couldn’t resist buying it. It is an example of the desire to automate and the fast growing ability to do so using more and more complex technology in commercially available machines.  Starting in the mid 60’s this development becomes superfluous with the rise of the until then fairly unknown new semiconductor technology.  While it took 30 years to develop from Walther’s EMKD to -for example-  the Olympia RA16, it took only 6 years to bridge the technology gap between the Olympia CD400 and the programmable HP97.

The machine  supports semi-automatic multiplication as well as fully automatic division.  The right carriage shift is motorised, the left shift is spring operated. It’s a real “machine” with a service hood  and many oil holes.

My version shows very little wear  e.g. of the motor collector and the centrifugal rpm limiter.  Electrically it’s not safe. It’s not grounded and to make things worse inside the motor there is a 75kOhm connection with the motor housing; I can’t use it without an isolation transformer.



As usual for this type of machine


The top-right switch determines the number of additions when the + button is pressed. The largest number of the multiplication is entered in the input register, the smallest is entered from right to left in this switch. After each operation the carriage is moved one position to the right.  The advantage compared to manual multiplication is that it’s not necessary anymore to closely watch the counter while pressing the + button.


Move the carriage all the way to the right.  

Enter the dividend in the result register with a + operation.  

Enter the divisor in the input register.   

Pushing the : button starts the automatic division process which ends when the carriage has reached the extreme left.  The : button is not automatically released. To release it, pull it a little bit towards the operator.  While pressing it to start a division you may need to push it a little bit from the operator to assure that the division is completely finished.  This part seems to be different from other EMKD’s I have seen on the internet.

The quotient is in the counter register (left), the remainder is in the result register (right).

Function of some keys, switches etc

Calculator InfoWalther EMKDWalther EMKDWalther EMKDWalther EMKD

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Serial number:

Built in:


Rotation speed:


Production until:


11826  (The motor-nr  2473 is visible above the mains connector as well as on the motor itself)

Approx. 1935  (rough guess based on serial number info found on http://www.rechnerlexikon.de)

Addition, Subtraction,  Semi-automatic multiplication, Fully automatic division

300 /min



Approx. DM. 700,- in 1930 (Source:  http://www.boelters.de)

Walther EMKD Walther EMKD Repair information & pictures of internals Video