Will data on floppy disks be safe from magnets?
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- Опубліковано 7 сер 2024
- Have you ever wondered what will happen when you place your floppy disks too close to your PC speakers? Were you worried when you noticed that you left some floppy disks on top of your monitor? In this video, I will examine how well a floppy disk preserves data when exposed to neodymium magnets.
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00:00 Intro
01:56 Test setup
02:45 Distances to magnets
04:40 We need to get closer
06:21 Corrupt a single file
09:11 Scandisk to the rescue?
10:12 Erase entire disk with magnets
11:06 Conclusion - Розваги
You should have used BMP format so bytes could be corrupted and directly display the damage in picture...
Would a checksum of the data before and after the tests not suffice to determine data corruption?
Absolutely! If I make a follow-up, I will use checksums.
Interesting experiment, I like these testing videos. PC speakers are shielded, but the magnet works differently. A rapidly changing magnetic field causes more harm to disks than a static field.
Couple notes: Jpg typically can still load with data corruption, I would have liked to see what an app that loads even with an error would have made of the data that was available. (image the floppy and replace the unreadable bits with 0's or something). I thought there was a component of the magnets corrupting data where you need to move the magnet to get them to corrupt the data. Perhaps more motion on the tests where the data did not see an effect would have seen corruption if you moved the disk or magnet more.
Very good inputs! Thank you for sharing your thoughts. I will compile all the ideas I get from this video and come up with a better analysis, testing method, and maybe recovery options.
Floppies from what I remember at least at the BIOS level won't replace unreadable bits and won't even provide a partial read.
Perhaps at the FDC level you might actually be able to overcome that.
I know AH=04h, INT 13h "Verify Disk Sectors" has error codes for "ECC/CRC error" and "recoverable data fixed by ECC" errors
@@eadwacer524 yes, the OS will not let you get partial data it will just tell you its bad. It will have a few goes though before it borks out. You can hear it retry and if that doesn't work it will go back to the first sector and then count the steps back again to ensure the head is aligned and it will do that I think about 5 times before it issues a fail. HDD's do the same, and you hear it click a few times whilst it not only tries to retrack but also ensure the disk is spinning at the correct speed. These are absolute marvels that a mechanical device can have such accuracy, I have no clue how you can possible conceive of a 16TB disk, you would have thought that totally impossible. The run-out of the bearings is 100's megabytes wide alone. It really is magic. I find flash memory far less magic.
@@eadwacer524 Kryoflux? Even without some of the tools used to copy floppies with copy protection just skipping sectors when making the image would allow you to zero those sectors out on the image file.... the ? of weather a 512B / 200KB image is noticeable bothered me enough to check and it is indeed viewable. While I know it's an issue, hopefully he can read at least some of the corrupted sectors it'll make the error patterns on the JPG more interesting.
The data is stored as an analogue flux signal. It looks for changes in this to determine the data, the absolute flux level isn't important so putting static magnets next to the disk provided it doesn't drive the flux right into to saturation will in most cases still be readable - thats what's great about digital data. To erase the disk you not only need a very strong magnet with the flux in exactly the right direction, but an alternating current is far better because it leave it degaussed. Even if a disk has been written to with 1's (FF's) a determined data recovery specialist can get lucky and retrieve the data because what was a 0 before is weaker than 1 which was 1 previously. Data recovery systems would look at the signal and vary the point at which it decides if its a 0 or 1 and you can get data back that way. Same applies to HDD's although its actually a lot more complicated and the amount of data is so huge that its unviable. I don't think that leaving magnets near the disk for a length of time will make any difference, its the process of flux moving through the disk that will affect it. I do know though that the magnetic flux does degrade with time, but its usually a chemical degradation or contamination or misalignment of the read-write that was the issue. As for leaving on your speaker, you're probably safe but the degausse coil that pings every time you turn an old CRT monitor on is a definite risk to magnetic media.
Interesting! Now we need the floppy on top of the CRT monitor, degaussing coil test :-)
I tried years ago. Putting a floppy on the screen of a 21" flat Trinitron and degaussing had no noticeable effect. I don't know how placing disks on top of the monitor would work, I imagine it would also have no effect.
Worth noting: My dad sometimes takes apart hard drives, and he keeps the head arms stuck to the furnace duct in his workshop. They're permanent magnets, and pretty strong ones at that. If a hard drive can handle those things constantly sweeping back and forth just a couple millimeters from the platter, they must be pretty resistant to magnetic fields. I don't know if there's a major difference in tolerance levels between a floppy and a hard drive; I would imagine if anything that the hard drive is even more sensitive because of just how much data has to be crammed into the same space.
This makes me feel a lot better about setting my headphones next to a rare famicom disk game that was in a plastic box for a split second
The speakers may still be more harmful than your static magnets. In speakers, when in use, the magnetic field is constantly changing. Like the electric demagnetisers to undo magnetized stuff.
You could also just move the magnet really fast from left to right at a distance to simulate that... or just open up a speaker.
That's not actually true. The speaker driver consists of a large stationary magnet that surrounds a coil in a very strong magnetic field. There's two halves of this static magnetic field, one running inside the driver assembly that the coil is suspended in, and the spillover outside the magnet-polepiece assembly. There is a dynamic magnetic field created on the coil which interacts with the static magnetic field to induce movement, but it's super localised to the coil and its immediate vicinity, it doesn't actually leave the magnetic gap much at all, infinitesimal amounts, and it isn't actually strong at all to begin with.
Speakers intended for use near TVs/monitors are not dynamically magnetically compensated, they are not compensated against changing magnetic fields. Instead the inner polepiece is followed by a second ring magnet, identical to the ring magnet that provides the magnetic field for the coil, epoxied on it in reverse polarity, and a steel cap intended to short circuit most of the spilling out static magnetic field. If it was so as you describe, that there was a changing magnetic field spilling out, CRT monitors would still be affected when the speakers are operating, but this isn't the case. CRTs are very sensitive to magnetic fields, it doesn't take much to change the path of an electron in a vacuum along a fairly longish path.
@SianaGearz You have not seen my CRT that unwillingly gone disco mode just because I played some music. The static field was far less noticeable. Maybe slowly creeping in... As usual degaussing the display made it all fine. But as soon I played music it went back to disco mode. Don't forget that many just had very cheap desktop speakers. I had that problem with almost all of mine. I once put my computer next to the speakers of my dads stereo and there was absolutely nothing. The Quality of the speakers really make a difference.
Additionally now I wonder... Put a floppy on top a CRT and start a degaussing that CRT. Hmm...
Exactly, variating magnetic flux will cause more damage than a static one, a test is needed !
@@5Breaker That is interesting. Well i've had all sorts of things. I use ELAC BS52 as computer speakers, but i think i might have gotten them after i switched to LCDs, i don't remember. Before that i had a Quadral kit and also i have had a KYE Genius wooden computer speakers set. Also a Panasonic boombox. I don't remember ever causing a dancing image with either of those.
I am liking the idea of the degauss floppy experiment.
I've been always wondered how critical placing a magnet close to a floppy was! Thanks for answering that question!
It was also something I wanted to experiment with myself. Through the comments, I got a lot of good input and ideas for future content. Thanks Tony for watching!
Depends on the strength of the magnets. When I wrote my floppy imaging tool, I needed to make "bad" disks to test error recovery, so I used a small rare earth magnet the size of a bb (about 5mm) to "burn" a spot in the disk and it took only one second of putting it within 1cm of the disk wafer.
Every video you post is excellent. Thank you very much for making such great content!
Thank you! I try my best making a lot more content in the future!
I once without thinking left an external hard drive on a subwoofer for weeks/months. When I connected it to the computer it took hours to be accessible. I dont recall data being lost and I think it was a new empty drive but it was an education for me for sure.
I'm sure someone else in the comments has pointed this out, but static magnetic fields don't have much of an effect. The damage, if any, will be during the time you are moving the floppy in and out near the magnets, which causes eddy currents in the magnetic media and thus can scramble the magnetic fields. This is also why speakers in particular could be bad -- when playing audio, you have a dynamically changing magnetic field which is more likely to cause issues. Also, if you put the floppy near a CRT when it turns on and fires its degaussing mechanism, a huge spike of sudden magnetic flux happens that could definitely cause some issues. In all cases though, it depends on the direction of the magnetic field relative to the disk surface. I imagine that moving magnetic fields parallel to the disk surface would probably be worse than those passing perpendicularly to it, as it would probably cover more of the disk area.
If you wanted to do this experiment a little more scientifically, you could create a small electromagnet by winding a coil of wire around a piece of ferrite. Then use either those magnetic viewer films or iron filings to visualize the magnetic field created as you apply a small AC waveform to the coil. Or, if you can afford it, get a fluxometer, I think you can get them on eBay fairly cheaply these days. This will tell you not only the magnitude of the field in Gauss, but can also help you figure out the orientation of the field. However, a coil wound around a ferrite rod has a fairly predictable magnetic field, so you can just place it in one spot and then try moving the floppy to various spots, energizing the magnet, turn it off, and then test the data.
Goes to show how resilient those 3.5" floppy disks truly are! Sony did a good job designing them to retain data through normal daily conditions. I've come across many disks that still retained data that was well over 30 years old. Were still perfectly readable all those years later.
Would be curious as to how susceptible a 5.25" floppy would be to such magnetic fields. I think the thinner outer case wouldn't afford as much protection.
I was surprised how well the data was preserved. I do have a 5.25" drive in Germany - which I don't know if it still works. I should take it with me next time I am there - and get some floppies for it too!
From personal experience i can say, the larger 5.25" floppies are much better in keeping the data. The lower density seems to help here.
@@OpenGL4ever That makes sense! Would still make an interesting video, though.
@@OpenGL4ever I think most of the problem, is that 3.5" floppies were in use until late 90s, early 2000s, when their value was rapidly declining and good manufacturers of magnetic material started closing shop, and so many floppies that are retained from that era are just low quality junk.
@@SianaGearz No, that's not the reason. I bought them in the early 1990 when they where on their peak and not on their decline. The 5.25" are juster better in this regard.
You should have tested with speakers, because their magnetic field fluctuates to generate the sound and could have a different effect than static magnets.
An idea for a future video: effect of scratches/dust on CD/DVD disks...
A moving magnet or magnetic field is what erases. Hence moving head or even in a tape unit the tape moves past a record or erase head. Static fields don’t generally cause as much issue.
Cheap recorders have a permanent-magnet erase head but if you think about it, the movement speed of the tape against the erase head is spectacularly slow, so the erasing action is basically just due to static magnetic field. Furthermore it's not like the tape is erased quicker while you rewind it and the permanent magnet is in a "disengaged" position several millimetres away from the tape!
@@SianaGearz These work by saturating the tape such that you cannot recover the signal. If you play a tape that was recorded after it was erased this way, its much more noisy because the recording is distorted by the flux offset. What I have never tried and now I suddenly want to is recording over a tape when the erase head is disconnected. Does it just sort of sum them or does it mess it up entirely? Last tape recorder I had is 25 years ago by now.
@@dr_jaymz That is a curious experiment to perform.
@@SianaGearz its not a static magnetic field as the tape it moving - move the tape or move the magnet and the result is the same. In a cassette deck the erase head has the tape pulled across the surface so its as close as can be to affect it. Retracting (or not engaging more to the point) the perm head doesnt cause issue as its far enough away and in an active erase head as long as its not powered it wont cause issue. I still use my 3 head Dolby S / HX Pro deck now and then and it surprises me how great a sound using a good deck and tape can give!
@@dr_jaymz I tried this decades ago and it kinda sums them but the previous recording is dulled with the new one having more presence and killing the previous one's treble and volume.
Degausser adventure would be fun.
You need changing electromagnetic field to damage data, replace magnets with coils, or simply put floppy between phone and wireless charger, should be enough
lovely
Nice Video! Die von der AI erstellten Damen sind wirklich gut gelungen. Extrem hübsche Artwork.
Ive done experaments on this, It depends on the strength of the magnet and proximity, but a powerfull magnet WILL erase a disk.
thanks i was looking for a way to erase disks corrupted by misaligned drives
most speakers used in computers and tv's are magnetically shielded either by 2nd magnet in a metal case canceling the field or by installing on metal case elements if magnet is small
the thing that breaks dicks is to place them on oscilating fiels like monitor degaus coil or magnetic assembly or transformer soldering iron
i belive random magnets wouldn't do much to a floppy, unless you place them with magnetic field going directly though the disc if you get a compas and find magnetic poles of your magnets you can do the most damage with magnet north or south edges
? are compressed EXE files harder to recover from a floppy
then uncompressed EXE files (some EXE files are compressed by default)
it's not the "being next to magnet" it's the changing field by moving magnets !
I'm curious as to whether 6.jpg opened after fixing the bad sector, and if so what it looked it.
No, the picture did not load after scandisk. I get a lot of feedback and will probably make a follow-up in the future.
I wonder if alternating magnetic field would be more destructive. Instead of just trying to flip the bits it would rather shake them around.
it definitely does, thats why bulk erasers and de-gausses are AC.
Would a strong magnet damage data on an HDD?
I can imagine that when the magnet is strong enough, it will damage that data - and maybe even some mechanical parts of the hard drive.
Was the jpeg able to be opened after scandisk had marked and reallocated the "bad" sector?
No, the file was still not able to load.
hmm i'd be curious to see if Spinrite 5 would be able to recover the bad sector in that last scenario.
Thank you for the suggestion of Spinrite 5 - I will have a look at it.
@@bitsundbolts no prob i know 6 is out there but i've seen reports 5 is best for testing and recovering floppies far more than 6.
Now test this with kryoflux what is left when dos does give up
But you only use shielded speakers on a PC.
Floppies don't have physical tracks or sectors, so they can't be destroyed. Everything is virtual. The 80 tracks were simply "it works without issues" decision .
Scandisk can't reconstruct data, it just searches for unreadable areas or logical errors. If you destroy the data in binary form, scandisk is always unable to help.
so a steel/iron core casing would divert magnetic fields away from the disc, protecting it
ie magnetic field will go through preferentially a strong magnetic iron core
ac magnetic field is different than dc magnetic field
disk is not a rom
Tell us more about the .jpg files. I’d like to replicate the tests exactly. I must use the same files. 😂
Hehe
Hard drives have a poweful magnet inside so I guess if the magnetic field isn't strong enough it can be there for years.
Aren't these powerful magnets shielded with a paramagnetic material, just like "multimedia speakers" are designed to be placed closely to CRT screens without distorting the image.
The magnets in a harddrive are shielded. The magnetic field never comes in contact with the platters.
@@MrRobarino The shielding is not perfect, but in any case you have to remove the top magnet along with its shield to replace the heads, and to remove it you have to face it towards the platters and nothing happens to the data stored on them, the magnetic particles aren't that sensitive to magnetic fields.
"Promo SM" ✔️
Your test doesn't make much sense since you can't see bitflips in JPEG files. If a bit flips there, the image information changes minimally, but that's in most cases not noticeable. It would be better if you provided the files with MD5 or SHA256 checksums and then check the files with the checksums.
Also, you overformatted the floppy disks. The normal disk format for 3.5 HD disks is approximately 1.44 MiB and not the larger none-standard formats. With the latter, data loss is also more likely. And yes, of course MS-DOS tools cannot read and use the non-standard larger floppy formats.
You are probably right that single bit flips are difficult to detect with JPEG files. For now, it was just an idea, but if I make a follow-up, I will definitely use checksum to validate data. I get a lot of good input - thanks!
@@bitsundbolts You're welcome!
AI 🤮
Huh?