Diehl DSR18


The Diehl DSR18 is a high-end machine with lots of  controls to determine how the machine operates.  It is one of the rare machines with a real memory register.  It not only allows to calculate an overall sum while performing adjacent calculations, but for further calculations the contents of the memory register can also be read back into either the result register (one dot) or the input register.

Less perfect is the implementation of multiplication. It’s only semi automatic and digits must be entered in a less natural reverse order.
The Marchants like the 10AFE multiply in the same way, but at choice digits can be entered from low to high or vice versa.  They also operate fast enough to keep up with normal digit entry speeds.  This DSR can’t.

While working on my machine it sometimes blocked while multiplying.  I noticed the opening on the left bottom which gives access to  an overal control reset (see photo above).  It can be easily reached when the machine is in its normal  operating  position.  Pulling it forward often got me out of the blocking condition.  



As usual using the “+” and “-” keys.


Enter 1st number in the keyboard.  Next use the most-left column to enter the digits of the second number.   The second number must be entered in reversed order, i.e. from right to left.


Enter the 1st  number,  push the ‘L’ key. Then enter the 2nd number and push both the ‘#o’ and “o” key..

Remark: The ‘L’ key  resets register 1 first,  the ‘V’ key does not.  

Function of all keys, switches etc:

See the assets page of this machine

Calculator Info Repair information & pictures of internals
P1000797as.jpg P1000795as.jpg P1000804as.jpg

Click to view a full size picture (opens in a new tab)

Video Assets: adverts, brochures, etc

Serial number:

Build in:


Rotation speed:


Production until:


32 292

Ca. 1960

Addition, Subtraction, Semi Automatic Multiplication and Division

430 operations/min  (To lower mechanical stress I’ve set it to 390)



DM 4250 in 1961 (Bron: BüromaschinenLexikon)