4 ms·

The key to long life for valve (tube) computers was never turning it off.

• klodolph 7y ago
  That’s not really the key. When ENIAC was first run, several tubes would fail each day—and yes, it was turned on all the time. They addressed these problems by adjusting heater currents. In general, there’s a tradeoff here because you don’t want to strip the cathode (which can wear out a tube quickly) and you want good performance from the tube. The on-off cycle effect on filaments is also largely due to surge currents with a cold tube, at least for typical designs, and there are various techniques to limit the surge currents which will extend tube life.