Everything important is using ECC and low-level parity bit protection.
this post was submitted on 11 Feb 2024
143 points (92.8% liked)
Showerthoughts
30562 readers
1292 users here now
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. The most popular seem to be lighthearted, clever little truths, hidden in daily life.
Here are some examples to inspire your own showerthoughts: 1
Rules
- All posts must be showerthoughts
- The entire showerthought must be in the title
- No politics
- If your topic is in a grey area, please phrase it to emphasize the fascinating aspects, not the dramatic aspects. You can do this by avoiding overly politicized terms such as "capitalism" and "communism". If you must make comparisons, you can say something is different without saying something is better/worse.
- A good place for politics is c/politicaldiscussion
- If you feel strongly that you want politics back, please volunteer as a mod.
- Posts must be original/unique
- Adhere to Lemmy's Code of Conduct
If you made it this far, showerthoughts is accepting new mods. This community is generally tame so its not a lot of work, but having a few more mods would help reports get addressed a little sooner.
Whats it like to be a mod? Reports just show up as messages in your Lemmy inbox, and if a different mod has already addressed the report the message goes away and you never worry about it.
founded 2 years ago
MODERATORS
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.