Marchant 8ADX


While competitors use the amount of displacement determined by an input module,  this machine uses speed to transfer key-input to the accumulator. To do so keys in each column are connected to a kind of gearbox with 9 speeds.  If a “1” is pushed, the lowest gear is activated, if a “2” is pushed, the second gear is activated and so on.  When a calculation operation is activated (e.g. “+”) the machine makes a rotation to transfer the selected digits from all columns into the accumulator.

While this is an analogue operation, a smart construction properly digitises the results at the end of the operation.

 It’s advertised as  a “Silent speed mechanism”.  The fact that the actual calculation process is analogue allows for continuous rotation when adding/subtracting for multiplication and division.  It makes the machine fast enough to directly input the multiplier one digit after the other while the machine is calculating. As a result  there is no need for a multiplication register.

Furthermore, during division there is a smart detection system to predict wether a next subtraction will end with a negative result.  In that case the next division does not take place.  In stead the carriage is moved to the next position. Doing so saves an unnecessary subtraction as well as a the related corrective addition.  The silent speed mechanism + the prediction mechanism are the reasons why in particular  a division is executed much faster than on competitive machines.



Enter a number and hit the “+” or the “-” key.


Enter the first number in the main input field.  Enter the second number in the rightmost column.  Multiplication is immediately executed per entered digit. The order of input for the second number is right to left)


Enter the first number and hit the “+” key.  Enter the second number and hit the “:” key. The division is now executed. The result appears in the upper register.

Function of some keys, switches etc

Calculator InfoRepair information & pictures of internals
Marchant 8ADXMarchant 8ADXMarchant 8ADX
Marchant 8ADXMarchant 8ADX

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Video Assets: adverts, brochures, etc

Serial number:

Built in:


Rotation speed:


Production until:


R-8ADX 582317-H

1958/1959 (*)

Addition, Subtraction, Fully automatic  Multiplication and  Fully automatic Division

1000 additions or subtractions per min.


1962 ?  It was still offered in 1962/1963 (Source: Büromaschinen Lexikon)

Approx. DM. 2975 in 1958     (Source: Büromaschinen Lexikon)

(*) The list in  shows ascending numbers up to ADX548 in 1957.  This, together with the appearance in Büromaschinen Lexikon untill 1962 makes me believe that this machine was build one or two years later.  By that time Marchant had merged with Smith Corona to form the SCM Corporation (source: My Years with Marchant by Ernie Jorgenson).