Baba,

Thermionc valves preceeded transistors it seems. 

I remember father thumping the top of the wireless to reseat the valves whenever it played up. 

I googled the following:

The invention of the transistor in 1947 opened the door to the information age as we know it. But computers existed before transistors did, albeit in a rather rudimentary form. ... Rather than being built out of transistors, these behemoth computers were made up of something called thermionic valves, aka vacuum tubes.18 Jan 2018