Everything important is using ECC and low-level parity bit protection.
this post was submitted on 11 Feb 2024
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in a perfect world, perhaps. but we don't live in one.
Are PDP-11 computers still in use?
The PDP-11 is definitely still in use today, thanks to its unique and strong build. It is still used to power a GE nuclear power-plant robotic application — and will do so until 2050.
Technically, due to its potency, it is still used by the US Navy in its ship radar systems and by Airbus SAS. There are also rumors that it is part of the set up in the British Atomic Weapons Establishment.
Thanks Intel for making this statement false
These have a high probability of working but it isn't perfect. And not all of them tell you which way the bit was flipped.
Ok, I'll bite: what's a "cosmic ray bit-flip"?
So basically, we have low level neutron radiation coming at us at all times from space. Mostly from our own sun, some other external sources too. It takes a whole lot of concrete or lead or water to stop that completely, so anything that makes it through our atmosphere is harmlessly passing through all of us.
But since things like computer RAM and other electronic storage have gotten so much smaller, this radiation is now capable of energizing or discharging individual bits — 1s or 0s — in that storage. Imagine you’re in the hospital for a back operation and the robot arm is approaching a 1 bit that tells it to stop… but that 1 flips to a 0 because the sun sneezed and now your spine is in two fun-sized pieces.
This is all mostly moot today, though. ECC-enabled RAM (memory with protections against bit flips) is the norm and this is a pretty well-understood problem.
Ok, there just has to be a movie that capitalizes on this idea.
One definitely could be made. That physics caused a miscount in a local election iirc. That's probably a good movie premise.
In case you're missing it, this is what the Stephen King book and movie "Maximum Overdrive" is about, but technologically behind by 50 years. Radio signals and power surges just happen to influence machines all over the world into vengefully killing people.
Please explain the soda machine gag to me, I just can't wrap my head around it 😂
Maximum Overdrive?
Should mention that the robot does not depend on a 1 to stop, more on like 600 in any "modern" programming language. 😅
Nearly every computer you use, including the ones people are starting to use for self-driving, can have their memory accidentally modified from cosmic rays
We try really hard to protect spaceships from them, since they’re subject to more
However, due to the law of large numbers, sometimes your computer will get random bit flips - where it should be a 0, but it’s instead a 1, or vice versa
Cosmic ray zaps your silicon just right to flip a bit. If you've heard of the Tick Tock Clock upwarp in Mario 64, most people suspect that's what happened.
On first thought : yes.
But on second thought : no (i.e. : not really, because of system's redundancies)
I thought we already had a way to deal with bit flips. CPU bit flips should be common by now because of the size of processors these days.
Yup. There is technology to deal with this. But does every piece of hw have that tech? No. Does every piece of sw run eccs for this purpose? No.
Explain?
More computers dealing with more parts of your life increases the chance that a bit flip has a negative effect
What is a bit flip?
Computers store everything as electric current. If the current is on it's a one. If the current is off it's a zero. High energy particles from outer space regularly blast through our upper atmosphere into the Earth passing through most solid matter. These high energy particles can induce the electric currents when they impact computer components. These erant current can cause a one to become a zero or a zero to become a one. This can have all kinds of interesting effects depending on which zero and one got changed when and where. Normally this causes a crash of the program or operating system.