3 ms·

Would tube reliability have limited how much you could scale it up? As far as I know, tubes have a limited lifetime and burn out eventually. If you have a milli

Would tube reliability have limited how much you could scale it up? As far as I know, tubes have a limited lifetime and burn out eventually. If you have a million or a billion of them, they might fail so fast that your computer simply doesn't work. I don't know whether reliability is a solvable problem. Tube-based devices were once very common, so that suggests it would have been solved if it could have been.

klodolph 2y ago
Tubes have a limited lifetime, but high-reliability, long-life tubes were developed specifically for digital circuits. One such development was a change in alloys for the filaments. It turns out that the filaments were made from a tungsten alloy containing silicon, and the silicon evaporates and is deposited on the cathode. The cathode has a special coating to help it emit electrons, and the silicon deposits would interfere. From what I can tell, the alloy for filaments had silicon in to make it easier to draw through the dies necessary to construct the filament in the first place, so there is some tradeoff between the lifetime of the tools used to make the tubes and the lifetime of the tubes themselves. This is not entirely unlike the problems faced by semiconductor manufacturers—problems with impurities, solid state chemistry, and vapor deposition. I can imagine an alternate timeline with extremely long-lived vacuum tube circuits.
- shrubble 2y ago
  I recently read up on "zone melting" which was developed to purify germanium - but of course this same method can be used for other materials. Interesting that Hamming of Hamming codes fame gave encouragement to the developer of this materials process: https://fs.blog/great-talks/richard-hamming-your-research/ https://fs.blog/great-talks/richard-hamming-your-research/ (search for Bill Pfann)
actionfromafar 2y ago
Say a CPU was made the size and shape of a plasma TV. You wouldn't have to run it all at once. You could make many CPUs or logic blocks and re-route traffic to hitherto unused blocks when a fault was detected.
- anyfoo 2y ago
  Oof. I don't know much about tubes, do they always fail in ways that are reliable to detect? (E.g. I can imagine that detecting a burned out heater is easy, but I don't know what other common failure modes there are.) And even then there's a lot of effort to just make the system "switch over"... and a lot of extra real estate with technology that was already constrained by the minimum size bound of the tubes.
  - actionfromafar 2y ago
    I was thinking pretty high level stuff, like running a quorum of CPUs or something. But it could also be a manual thing with switches on a panel. :)

klodolph 2y ago

Tubes have a limited lifetime, but high-reliability, long-life tubes were developed specifically for digital circuits. One such development was a change in alloys for the filaments. It turns out that the filaments were made from a tungsten alloy containing silicon, and the silicon evaporates and is deposited on the cathode. The cathode has a special coating to help it emit electrons, and the silicon deposits would interfere. From what I can tell, the alloy for filaments had silicon in to make it easier to draw through the dies necessary to construct the filament in the first place, so there is some tradeoff between the lifetime of the tools used to make the tubes and the lifetime of the tubes themselves. This is not entirely unlike the problems faced by semiconductor manufacturers—problems with impurities, solid state chemistry, and vapor deposition. I can imagine an alternate timeline with extremely long-lived vacuum tube circuits.

shrubble 2y ago
I recently read up on "zone melting" which was developed to purify germanium - but of course this same method can be used for other materials. Interesting that Hamming of Hamming codes fame gave encouragement to the developer of this materials process: https://fs.blog/great-talks/richard-hamming-your-research/ https://fs.blog/great-talks/richard-hamming-your-research/ (search for Bill Pfann)

actionfromafar 2y ago

Say a CPU was made the size and shape of a plasma TV. You wouldn't have to run it all at once. You could make many CPUs or logic blocks and re-route traffic to hitherto unused blocks when a fault was detected.

anyfoo 2y ago
Oof. I don't know much about tubes, do they always fail in ways that are reliable to detect? (E.g. I can imagine that detecting a burned out heater is easy, but I don't know what other common failure modes there are.) And even then there's a lot of effort to just make the system "switch over"... and a lot of extra real estate with technology that was already constrained by the minimum size bound of the tubes.
- actionfromafar 2y ago
  I was thinking pretty high level stuff, like running a quorum of CPUs or something. But it could also be a manual thing with switches on a panel. :)