I can recall seeing something like this in a magazine decades ago but my recollections are vague—although if I saw the photo of the device that accompanied the article then I'd reckon I'd still recognize it.<p>Essentially, it was a miniature filament-less vacuum tube with I think a silicon emitter/cathode that looked somewhat volcano shaped, the top of which electrons were emitted by electric field emission rather than the more usual thermionic emission.<p>I cannot now vouch for the size of it but a tiny nuvistor, <a href="https://en.wikipedia.org/wiki/Nuvistor" rel="nofollow">https://en.wikipedia.org/wiki/Nuvistor</a>, along side of it would have been a giant by comparison.<p>I'd be interested if anyone has a better recollection than me and if this is essentially the same device as mentioned in the article.
Ha, this reminds me of Pratchett's <i>other</i> discworld...<p>"Kin had seen things like it in a museum. It was a valve, a sort of neolithic integrated circuit. Only this was a valve such as might be built by someone who had never developed the transistor, so that more and more ingenuity had been devoted to perfecting the existing technology." -- Strata, Terry Pratchett.