PPS. Even a
all tube computer has solid state diodes.
It did not have to. There are computer rated 6AL5s. I forget the number.
And if you expand on Roger's (yes, from the Great White North) 6074
(number?) Addatron concept, you do not need any diodes to provide
gating for logic functions. A complete full adder in a nine pin mini
tube, all done with steering the electron beams in a very clever way.
Certainly you could make all sorts of different gates by moving the
elements around.
Any tubes around I wonder ... make a nice demo machine.