This model is the simplest and cheapest one. It has, however, an electrical engine. Situated above the keyboard and constructed to move both to the left and to the right relative to the body of the machine is the Carriage. This carries two registers: the upper register extending the full length of the carriage is the Product Register (or Accumulator), which displays the results of additions, subtractions, and multiplications performed by the machine. Its capacity is 12 digits. On the other models, its capacity is twice that of the keyboard. It is called “Register I”.
Immediately below the right-hand half of the “Product Register”, there is a second register, the “Counting Quotient” or “Revolutions Register”. Its main function is to record the number of additions or subtractions made in an operation and to display the quotient in division. Generally, on all models of Madas, its capacity is that of the keyboard, but on the model 12 and 12e, it is only 6 digits. It is called Register II.
Above the topmost row of keys, a special “Setting Register” is provided to see at a glance the number set on the keyboard, as soon as a key is depressed. It is called Register III.
Multiplication is performed by means of a sequence of repeated additions and carriage shifts, while Division employs a method of semi-automatic block-division. Carriage shift is always operated manually.
Later versions of this model were produced in a grey box, as it was for most models of the second period. It is an intermediate product between the black 12e and the fine 12eN.