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Cds are digital data storage discs that are etched in microscopic 1’s and 0’s in a microscopic spiral with a laser, and then later read back with lasers. You can only write them once but you can read them a million times. So grammatically, in the same way you “nuke” food in a microwave, you “burn” a cd in a cd drive that is capable of writing cds.

Maybe someday we can have cheap (cheaper than other storage media per gb), durable (last at least my lifetime), terabyte, fast read optical media. I would love to permanently store lots of stuff that doesn’t ever need to be rewritten.

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SpongyAneurysm@feddit.org ⁨4⁩ ⁨days⁩ ago

You can only write them once

CD-RW has entered the chat.

en.wikipedia.org/wiki/CD-RW

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echodot@feddit.uk ⁨4⁩ ⁨days⁩ ago
Well you etch pits you don’t actually actual numbers. Also it’s not a spiral, it’s not a record player it’s not been read by physical stylist so you don’t need a guide, they’re just concentric circles.

You start the disc off as a zero, then whenever you need to transition to a one you etch a pit, then it will continue to read that as one until you etch another pit and flip back to zero. So the sequence 0111001 would be etched as _...

Discs can also be overwritten, and used multiple times, you just wipe the entire top layer off and start again on the layer below, only really cheap CDs were single use.

As for the future there are already experimental crystal storage solutions (made out of artificial diamond so it would be essentially indestructible) which really are single use, but they can store hundreds of petabytes of data so you would probably just treat them as if they were rewritable. There’s also DNA storage but the equipment to save and read the data is nowhere near commercially viable yet.

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- SCmSTR@lemmy.blahaj.zone ⁨4⁩ ⁨days⁩ ago
  Ngl, i didn’t know it was concentric circles. I always thought it was a spiral like a vinyl record.
  
  Also the encode is pretty neat, I didn’t know that.
  
  I DID know about RWs being rewritable, and you could sort of brute force some supposedly single write discs.
  
  To be clear, I wrote that to be as simple as possible like if a person read it who really didn’t have any idea, they could have a relatively quick understanding in plain terms. Guess even I learned something today!
  
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- frezik@lemmy.blahaj.zone ⁨3⁩ ⁨days⁩ ago
  The pits just represent numbers. A 1-bit memory cell typically stores high or low voltage. The numbers 0 and 1 only exist as a platonic ideal, and there are many ways to represent them in the real world.
  
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Blue_Morpho@lemmy.world ⁨3⁩ ⁨days⁩ ago
There’s a Bluray media called MDisc that’s supposed to be more durable. It says 1000 years so I give it 100 based on the fact that the 100 year rated Verbatim AZZO DVD+R’s that I burned and verified to have low PIO errors had errors after 10 years stored in black cases in my temperature controlled basement.

People claim their burned DVD’s are all fine but I’ve never heard a post back when I asked if they’ve actually verified all the bits. “It reads when I put it in.” doesn’t mean there isn’t data corruption.

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- Buddahriffic@lemmy.world ⁨3⁩ ⁨days⁩ ago
  I recently learned of MDisc (there’s a CD and DVD version, too, iirc) and decided to get a burner and convert my old data CDs.
  
  While I haven’t verified every single bit, I did check that the files copied off of it were still functional and didn’t see any issues. Also didn’t get any errors. I was surprised because I’ve had some of them for over 20 years now and didn’t do more than put them in CD binders to protect them (during the days when I didn’t even consider the longevity of the media, other then obvious things like scratches.
  
  Only disc I wasn’t able to get the data from was a packet CD, which was a special format that facilitated treating the disc more like diskettes, where you could read or write at will via the filesystem rather than writing the disc as a special package from the start (or having multiple sessions if there’s still room on the disc after one such write). I was able to find references to the tech, though not if it was a standard or just a name a few different companies used for different implementations, but I wasn’t able to find Linux drivers that could do anything other than rip the ISO and a few strings or tell me it can’t find anything. Though it’s possible that corruption is really what happened here because I’d expect RW CDs to last a shorter time than the write once ones.
  
  Though I suppose I could try it on my old windows machine and see if drivers are more readily available there.
  
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  - Blue_Morpho@lemmy.world ⁨3⁩ ⁨days⁩ ago
    Where they CD or DVD? My CDs have lasted. It’s the DVD’s that had bit errors.
    
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    Buddahriffic@lemmy.world ⁨3⁩ ⁨days⁩ ago
    Yeah, those were CDs. I don’t think I got to the DVDs, since my sense of urgency faded after I saw the older ones seemed ok. I’ll have to check them out after you said that, though lol.
    
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missfrizzle@discuss.tchncs.de ⁨4⁩ ⁨days⁩ ago
I think there are some optical media like that. the discs are cheap but the readers are made of mithril.

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- SCmSTR@lemmy.blahaj.zone ⁨4⁩ ⁨days⁩ ago
  M-disc, I presume?
  
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- frezik@lemmy.blahaj.zone ⁨3⁩ ⁨days⁩ ago
  en.wikipedia.org/wiki/Holographic_Versatile_Disc - This one floundered and died before coming to market
  
  en.wikipedia.org/wiki/3D_optical_data_storage - A bunch of different solutions, and it looks like they were all being developed independently circa 2008, and then went nowhere
  
  My guess is that there’s not much use case beyond archival backups. That’s not going to get the economies of scale that CDs/DVDs/Blu-rays have. It’d be priced for the corporate market, but they already have perfectly good archival backup solutions. You’d also have to prove that it can be durable for at least a few decades, but even for commercial duplication, previous optical formats are just OK at best on longevity.
  
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  - missfrizzle@discuss.tchncs.de ⁨3⁩ ⁨days⁩ ago
    huh, I could have sworn there was a format for long-term archival, like 50+ years. I guess the GitHub Arctic Code Vault project went with microfilm using some very custom equipment to produce it all. but maybe everyone just uses tape (which is fun! but a bit less durable, and more finicky about being stored well)
    
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