So I've been thinking up a (alt-history)setting that aims to be a classic space opera, with the caveat that it will be completely hard science, with the only handwaving being what technologies do or do not exist. I don't want much computerisation or automation, since that will encourage manned spaceflight to develop. Arthur C. Clark speculated about telecommunications satellites, but thought that they would have to be manned stations since that the time only vacuum-tube based computers were available. In my setting this is the case, as solid state electronics were never invented / are not possible for some reason.
My question is this: If solid state electronics like transistors and diodes imply the possibility of eventually creating microchips(since they operate on the same fundamental principals), does the existence of vacuum-tube based computers also imply that solid state devices would eventually be developed?
I don't want there to be an inherent contradiction in having the one but not the other. Imagine how little sense it would make if we had two-stroke engines, but not four-stroke, and that is what I'm trying to avoid.