Re:Ask HN: Why did stack-based CPUs lose out?
by afiori on Sunday January 01, 2023 @03:27AM
(#34204665)
Not an expert but essentially radiations can produce electrons in random places flipping one or more transistors unexpectedly.
Larger transistors need more electrons so they are slightly more resistant.
Re:Ask HN: Why did stack-based CPUs lose out?
by denton-scratch on Sunday January 01, 2023 @07:50AM
(#34205909)
Because larger transistors need more electrons, they also need more power to switch. I guess that circuitry made from valves/vacuum tubes might provide high radiation resistance?
Re:Ask HN: Why did stack-based CPUs lose out?
by ilyt on Sunday January 01, 2023 @11:17AM
(#34207564)
I mean, you could just use big transistors
Re:Ask HN: Why did stack-based CPUs lose out?
by geomark on Sunday January 01, 2023 @10:23AM
(#34206985)
That's single event upset (SEU). The other radiation issue is total dose. That's when charge gradually builds up in insulating gates due to ionizing radiation. It's permanent, and eventually reaches the point that the transistor is always on so has a permanent fault. One of the factors is collection area, so larger gates are not less susceptible because they have a larger collection area. But if they run at a higher voltage that can make them more tolerant to total dose.
Nasa needs redundancy. Say we ran a program in triplicate, one on each core, and compared the outputs. We still don't have redundancy here because the chip can still fail in a way that will cause problems for all three cores.
>My second question, how much more resilient are older processes with larger feature size compared to modern 6/7nm ? Compare modern with older (14nm/22nm finfet, 28nm/32 soi) and ancient (65nm or larger).
Larger gates tend to be more resilient to radiation. I don't know exactly why. The fabrication tech is also important. Some types of chip manufacturing processes results in more resilient chips. I'm sorry but I don't know enough about it to elaborate further.