6 ms·

> When all the valves are glowing, I check the fire extinguisher is full, and run the code. It wasn't until working with valve hardware that I finally grokked

> When all the valves are glowing, I check the fire extinguisher is full, and run the code. It wasn't until working with valve hardware that I finally grokked the original difference between a cold boot and a warm one.

ahazred8ta 2y ago
♫ "And when they turn the power on, it's sure to dim the lamps / At plus and minus 16 volts and fourteen hundred amps." -- Frank Hayes
- Terr_ 2y ago
  Song audio: https://m.youtube.com/watch?v=bMS6G83NqFQ https://m.youtube.com/watch?v=bMS6G83NqFQ
- JJMcJ 2y ago
  Telephone central exchanges used to have enormous lead acid battery (like automobile batteries, the starter motor not the EV kind) arrays if they lost power. It was amazing to see the battery array discharge ammeter at 5000 amps when utility power went out.
  - _joel 2y ago
    some ISP's still do (or did, last time I was in one), at least one I worked for a few years back. Had a room full of lead acid batteries on shelves and another with a big spinning wheel to smooth out the flow.
kazinator 2y ago
What? Silicone hardware generates heat. Neither silicone hardware nor tube hardware goes literally cold in a cold boot; just the power is cut for a moment, usually not long enough to lose a lot of heat.
- tass 2y ago
  I imagine these terms could have changed over time, but consider that a warm boot might have meant power off and on with these old computers. One difference is that the valves have more chance of burning out on a cold boot due to the temperature change.
  - jaystraw 2y ago
    in the music world, variacs are used to bring old tube amplifiers up to power slowly for that reason. not after being repaired or refurbished generally, but certainly when the amp's condition is unknown. the author of tfa said his new power supplies do that automatically, which is pretty neat.
  - kazinator 2y ago
    Filaments experience a high inrush current on startup because their resistance is lower when they are cold. That's why incandescent bulbs often burn out on powerup, rather than in the middle of a duty cycle. Tube filaments last a good long time though, particularly in small signal tubes. They do not shine like light bulb filaments; they glow red. The circuit designer also has a say in it; tube filaments can be operated over a range of currents: you can run tubes hotter or colder. In a digital application, you'd probably want to go as cold as you can get away with for longer life. Tubes have various modes of failure in addition to burned out filaments, like "gassing out", or the cathode emission decreasing, eroding the gain. Of course, abnormal conditions like parts melting from overcurrent. Speaking of incandescent bulbs: those are victims of planned obsolescence. A bulb can easily be made that will last 50 years; it's just not profitable because you can't charge 50 times more for it than one that burns out in a year. Once everyone has 50 year bulbs, you're out of business.
    - ekidd 2y ago
      > Once everyone has 50 year bulbs, you're out of business. This seems to have been the issue with the expensive Philips Hue LED bulbs (the ZigBee ones). We installed ours close to a decade ago, and we took them with us when we moved to a new house. I don't think I've replaced a single one yet. Philips seems to have de-emphasized that set of bulbs in favor of cheaper models, as far as I can tell?

ahazred8ta 2y ago

♫ "And when they turn the power on, it's sure to dim the lamps / At plus and minus 16 volts and fourteen hundred amps." -- Frank Hayes

Terr_ 2y ago
Song audio: https://m.youtube.com/watch?v=bMS6G83NqFQ https://m.youtube.com/watch?v=bMS6G83NqFQ
JJMcJ 2y ago
Telephone central exchanges used to have enormous lead acid battery (like automobile batteries, the starter motor not the EV kind) arrays if they lost power. It was amazing to see the battery array discharge ammeter at 5000 amps when utility power went out.
- _joel 2y ago
  some ISP's still do (or did, last time I was in one), at least one I worked for a few years back. Had a room full of lead acid batteries on shelves and another with a big spinning wheel to smooth out the flow.

kazinator 2y ago

What? Silicone hardware generates heat. Neither silicone hardware nor tube hardware goes literally cold in a cold boot; just the power is cut for a moment, usually not long enough to lose a lot of heat.

tass 2y ago
I imagine these terms could have changed over time, but consider that a warm boot might have meant power off and on with these old computers. One difference is that the valves have more chance of burning out on a cold boot due to the temperature change.
- jaystraw 2y ago
  in the music world, variacs are used to bring old tube amplifiers up to power slowly for that reason. not after being repaired or refurbished generally, but certainly when the amp's condition is unknown. the author of tfa said his new power supplies do that automatically, which is pretty neat.
- kazinator 2y ago
  Filaments experience a high inrush current on startup because their resistance is lower when they are cold. That's why incandescent bulbs often burn out on powerup, rather than in the middle of a duty cycle. Tube filaments last a good long time though, particularly in small signal tubes. They do not shine like light bulb filaments; they glow red. The circuit designer also has a say in it; tube filaments can be operated over a range of currents: you can run tubes hotter or colder. In a digital application, you'd probably want to go as cold as you can get away with for longer life. Tubes have various modes of failure in addition to burned out filaments, like "gassing out", or the cathode emission decreasing, eroding the gain. Of course, abnormal conditions like parts melting from overcurrent. Speaking of incandescent bulbs: those are victims of planned obsolescence. A bulb can easily be made that will last 50 years; it's just not profitable because you can't charge 50 times more for it than one that burns out in a year. Once everyone has 50 year bulbs, you're out of business.
  - ekidd 2y ago
    > Once everyone has 50 year bulbs, you're out of business. This seems to have been the issue with the expensive Philips Hue LED bulbs (the ZigBee ones). We installed ours close to a decade ago, and we took them with us when we moved to a new house. I don't think I've replaced a single one yet. Philips seems to have de-emphasized that set of bulbs in favor of cheaper models, as far as I can tell?