This is a fully-automatic calculator. 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 20BZS, as the 20BS, 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 20BG or 20BTZG. This control permits to disengage the mechanism whereby, after multiplication, the carriage is returned automatically to its normal extreme left position.
Model 20BZS, 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. Unlike the model 20BS, there is no special lever, situated under dials 20 and 19 of Register I, to form the quotient when dividing not only in Register II but, simultaneously, in the left of Register I.
The three photos up above and below show the left-hand side of the carriage with 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.