In the “Original Series” chapter this very interesting Wikipedia article talks about the “hearing aid computer” that used the OC-71 germanium transistors which were used in hearing aids and could go only up to 25kHz clock rate. That was quite slow – tube computers could clock at 500kHz. Later models used faster transistors and could handle 500kHz. Then later, silicon transistors were even faster.
https://en.m.wikipedia.org/wiki/Ferranti_Argus
