5 ms·
Description of the issue from the original thread [0]: The processor in a modern, high volume device typically has its main clock driven by what's known as a M
by Cogito 8y ago
Description of the issue from the original thread [0]:
The processor in a modern, high volume device typically has its main clock driven by what's known as a MEMS oscillator. These are barely visible mechanical systems that resonate at some designed frequency, and include packaging to convert this resonance into a useful electrical clock signal. These devices are extraordinarily cheap ways to produce a steady clock, but they have a number of drawbacks. Most relevant, in order for these types of devices to function properly, the mechanical resonator must be inside a tiny hermetically sealed chamber with either a controlled gas inside or a vacuum, as the gas composition in the chamber can affect the output frequency.
For both cost and physics reasons, these hermetic seals are not perfect, and are somewhat commonly permeable to small atomic gasses such as helium.
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For this specific case, Apple devices probably share a common family of MEMS resonator to reduce manufacturing costs. This clock likely leaks in helium rich atmospheres, pushing the output frequency outside of the bounds that the main processors are designed to handle, rendering them non-functional. If left idle long enough, the devices may begin to function again, but depending on the concentration of helium which leaked in, this could take anywhere from weeks to years to occur in natural atmosphere and temperatures.
[0] https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabled_every_ios_device_in_facility/e7g5rcw/ https://www.reddit.com/r/sysadmin/comments/9mk2o7/mri_disabl...
- SilasX 8y ago>For this specific case, Apple devices probably share a common family of MEMS resonator to reduce manufacturing costs. At risk of provoking a standard flame war... They had mentioned that Android phones are unaffected, but don't those generally use even more "economical" manufacturing?
- Cogito 8y agoIt’s not economical in the sense of cheap parts, rather it’s economical in that Apple uses the same part in all devices. This can simplify supply chain and engineering efforts, so makes sense when possible. The comment is looking to explain why all the Apple devices failed; they were all affected by the same sensitivity to helium. Android devices tend to use a multitude of different parts to each other, so while some may have been affected you wouldn’t expect them all to fail in sync like the Apple devices did.
- SilasX 8y agoThe investigator reported that they couldn't find any Android with the error. >>There were also a lot of Android phones in the facility at the time, none of which were impacted. Somehow, all these commodity vendors all used designs that were resilient against helium.
- metalliqaz 8y agoApple does large enough volume that they have bespoke parts made. That could explain it.
- jolmg 8y agoAny android is not the same as any android in the facility. There must be a minuscule amount of different androids in the facility compared to the world market. I wouldn't think that designs vulnerable to helium are common enough to find one in a small sample, but the fact that Apple needs the same design for their ubiquitous phones makes the small chance of this happening take a big effect.
- Cogito 8y agoI agree that it's interesting they found no android devices that failed. Would love to see a more comprehensive study, looking at which devices fail at what levels, etc. Not that this is necessarily 'Not Invented Here' syndrome for Apple, as I think they may have compelling reasons to design and procure a bespoke component, the benefit of using something off the shelf is that it is battle tested by other people. You get a component tested not just on your use cases and failure modes, but everyone else's, so that if your needs or environment changes it's more likely for the component to keep working. I would also love to know more about how the enclosures used affects helium sensitivity; is helium pervasive enough that it gets everywhere anyway, or can some phone bodies etc keep it out.