This is a fully-automatic calculator. It is a relatively complex machine, which combines the possibilities of the 20AZV and 20AS. This model is subsequently improved under the designation “20BZS”. The features include tabulator buttons for predetermining the number of decimal places in division, as well as fixed decimal point alignment in multiplication. Once decimal points are set, they remain correct throughout all calculations. As for all automatic machines, there is an additional Register, the *“Control Register”*, also named *“Register V”*. This is necessary because, in automatic multiplication, the first factor in a product has to be stored while the second is set up.

It must be pointed out that the 20AZS, like the 20AS, has no *“Carriage Return Lever”*. On all other automatic models, this lever is situated on *“Register V”*, at left. See the difference, for example, with model 20AV. This control permits to disengage the mechanism whereby, after multiplication, the carriage is returned automatically to its normal extreme left position.

Model 20AZS, like all other models with a “Z” in the model-number, has a tens-carry-over which extends to the full capacity of the Product register (*Register I*), while models without “Z” have tens-carry to two dials to the left of that aligned with the extreme left-hand column of keys.

The two photos above show us the specific parts of the 20AZS. On the left-hand side of the carriage, one can see the particular mechanism of “Z” models. We distinguish clearly 9 small parts with rounded ends coming out of the carriage. These parts are pushed inside, when the carriage moves to the right, allowing to engage corresponding cogwheels, one after the other, when tens-carry is needed. We can also see the 9 tabulator stops, fitted on every “S” model. On the second picture at right, at the place where there is normally the “*Carriage Return lever*” (*Register V* at left), there is a hole. This mechanism is incompatible with that of the tabulator stops.