The model 20AT is definitely the forerunner of the most complex models 20B, the 20BTG and 20BTZG. “Register I”, the “Product Register”, displays the results of additions and subtractions and of multiplications performed by the machine. Its capacity is twice that of “Register III”, being twenty digits. “Register II”, the “Counting Register”, has a capacity of ten digits, but a second “Counting Register” is provided to the left of the first. While quotients, for instance, can be accumulated in the right-hand “Counting Register”, this second register clears automatically after each individual division.
Among the features that we find also on the most expensive models 20BTG and 20BTZG, there are two new Registers, “Register IV” and “Register V”. “Register IV” is an “Accumulator Product Register”. As its name implies, it accumulates successive products. It may be connected or disconnected at will.
On the front of the body, there is the “Register V”, also called Control-Register. This is necessary because, in full-automatic multiplication, the first factor in product has to be stored while the second is set up. Its capacity is also 10 digits. Moreover, a product formed in “Register I” may be transferred to the “Control Register” by operating a “Transfer-key”. This is a key marked by an arrow downward.
The commercial flyer, here below, shows an interesting summary of the capabilities of the “AT” family. The term “Tripolo” will be probably the source of the name “Triplex” defining the carriage of the models 20ATZ, 20ATG, 20ATZG, 20BTG and 20BTZG. The difference between the standard 20AT and the 20AT Tripolo is that the latter has no dividend setup.