Germanium transistors were first used in the calculating circuits of desktop calculators in very late 1963 or early 1964; it is now very difficult to pin down the exact dates.
There are three contenders to being the first caclulator since they were all announced at about the same time in different countries - these were:
Click on a picture to go to the page with more details and photographs.
A fourth very early calculator from the 1964/1965 period is the Mathatron, which is also a programmable model. There is an excellent description of this, with photographs, at Alex Knight's "The Calculator Museum - Desktop Calculator Gallery".
© Text & photographs copyright Nigel Tout 2000-2017 except where noted otherwise.