100 thoughts on “Magnetic Media (Floppies and Tapes) – Computerphile

  1. All the CRT's make this video impossible to watch for me. There's a constant high-pitched tone all the way through and it makes my head explode.

  2. I'm kind of disappointed. The guy spend a lot time describing how things rotate and how heads magically read magnetic data… I was expecting to hear about the actual read/write process. Sensors and precise numbers, speed comparisons, etc.

  3. While Compact Discs start at the spindle and spiral outwards, the numbering of floppy and hard disk tracks generally starts at the edge and increases towards the spindle.

    Audio Compact Cassettes (audio cassettes) normally have the supply reel on the left and the takeup reel on the right. The shown animation must be of a reversing deck 🙂 Love those autoreversing ones; gets to the end of the tape, senes the reels aren't moving, flips the head around, and starts rotating the reel on the left and the capstan in the opposite direction.

  4. Wish he'd talked more about variable sector/track drives. Apple used those in the early macs, and they sped up as things went along, producing a distinctive musical effect!

  5. Great to see smalltalk mentioned. As the first object oriented language written in itself it was decades ahead of its time. Even now there's nothing quite like it. It would make an excellent subject for a video.

  6. On the back of my 5 1/4 disks there's a pictograph saying do not store under 10c. Will freezing the disk really kill the magnetism?

  7. Music CDs were designed for constant linear speed, so the disc spins at 200 rpm near the rim and 500 rpm near the center. This wasn't a problem for music all read in order, but when you got to CD-ROM the drive would speed up and slow down constantly when it skipped around the disc. Eventually the constant speed drive became standard, and the drive would just read data slower closer to the center rather than speed up.

  8. How does the drive know which sector it is reading? Is there a special area somewhere on the disk that it can detect as it goes round?

  9. Seems kind of unfortunate though, that you read and write with angular speed, rather than surface area on the disk…

    But I guess it would be more complicated and probably expensive in terms of parts to vary the rotational speed of the disk…

    Because right now the theoretical limit of the information density on the disk, is determined by the track/sector closest to the center of the disk.
    Guess this would also make for a fun math problem in which you put number of tracks vs the writing desity and see which settings gets you the largest data capacity for the full disk.

  10. In a late 90's computer magazine I saw a review of a device that'd let you store data on a VHS tape. It let you store quite a large amount of data on a relatively cheap format, but the machine was expensive and it was slow as molasses.

  11. Don't forget the Exatron Stringy Floppy. An ultra-thin, continuous loop cassette. https://en.wikipedia.org/wiki/Exatron_Stringy_Floppy

  12. Fun fact: all floppy disks are double-sided. 3½" disk drives have two heads so they use both sides. But 5¼" ones have only one head and you could write only on one side because the other was mechanically marked as read-only. But if you punched a hole in the diskette with a special puncher, you could then write on the other side as well.

  13. IIRC the Apple IIe floppy drives used a variable-speed spindle for its floppies so the outer cylinders could have more sectors per track.

  14. I just dug out my old C64 the other day. It's so funny to work with actual "floppy" discs again. I even enjoy the awkwardness of it all 🙂

  15. Please, a followup video to show how magnetism is used to turn bits on and off, and why magnetic tapes/discs deteriorate over time.

  16. BS. A hard disc is much more involved than a floppy. The track alignment alone is just amazing in that it not only works, but is also robust. It's like saying an LP and a CD works the same. Might be true in a very general sense but there is a world of difference in the actual implementation.

  17. i'm still having nightmares about installing Windows with floppies and one of the last one is damaged…

  18. All of a sudden I feel I am old wathing this video. I have used those old floppy disks and magnetic tapes regularly on my old pc which was powered by a Intel Pentium(100Mhz ) Cpu. In my company I still use magnetic tapes for backups as they are lot more reliable than hdds and ssds.

  19. I almost became nostalgic while watching this video.
    Brings back good old memories when installing AutoCAD using 30 3.5" floppies on 25 PC. A good days work 😅

  20. And now I can have a MicroSD card the size of a pinky nail holding 128GB of media delivered to my house in 24 hours. I feel like we can't fully appreciate current tech unless we've all tried using floppy disks.

  21. Is there any technical reason why optical media like CDs only have one long spiral track while magnetic media like floppy disks or hard disks have many circular tracks?

  22. I've still got more than 160 analogue VHS tapes, and a working VCR. All of them my own recordings from German TV, roughly from 1995 to 2005.

  23. We had a silly joke once: Did you hear about the computer virus called Viagra? It changes your floppy disks into hard drives.

  24. I was hoping to see an explanation of the technical side a bit of magnetic data as well, on a molecular level. I know that these pieces of rust on the tape are like small magnets and the direction they are standing defines whether it will be read as a 1 or a 0, but would have loved to see a more in-depth explanation.

  25. On modern hard disks the outer tracks do hold more data, unlike floppies…
    if you measure the speed of a modern HDD, data near the start of the disk will be read or written faster than near the ending…

  26. Oh, man, there's a super high-pitch squeal in all Dr. Bagley's audio. I want to watch but it actually hurts a bit.

  27. One thing I like about technology is that it doesn't really get outdated. Sure the actual devices might become obsolete but the knowledge that makes them work the real "technology" can be used in strange new ways any time it fits the bill. It is very frustrating how careful marketing has directed consumers' definitions about technology. It's not the device, it is the study of the principles that make the device work. Too many people say they like technology but really just love consumer devices and would be bored to tears learning the technology itself.

  28. Hard disks can also be made of aluminum or ceramics, anything non-magnetic so eddy currents are not generated.

  29. 100 years from now, archaeologists will come across this video and scream at destruction of archival material.

  30. You missed the best part! you didn't record the glorious operating noise!
    That kachunk when you insert a 3.5" is so satisfying

  31. If you do a follow up could you explain how does the new japanese cd's and cassettes store more data than a normal crystal one. Thank you and great video.

  32. at 8:38 How is that connected to previous question?
    It answers why read/write speed is the same for inner/outer tracks, not how much data is stored.

  33. Wow, SMALLTALK/V 😉

    It is not impossible that I sold him that floppy disk while I was working for the company that imported it into the UK!

  34. This is awesome! Now I'd love to see a video explaining how SSDs work—or would it be essentially the same as the video on "How Computer Memory Works"?

  35. I would like to see a followup explaining more about the read write mechanism. And also an explanation of why punching a hole makes a disk double sided.

  36. 5.25" floppies? such newfangled stuff! you couldn't launch even nuclear rockets with those! 8" floppies is where it's at!

  37. Could you do a comparison between HDD and SSD data storage methods? Is there a why to visually describe the disk access speed between the two storage types?

  38. Rust is specifically iron (III) oxide; while if any iron compound is used in a magnetic coating, it would most likely be iron (II) oxide, similar to magnetite.

  39. It was really interesting but I couldn't finish it. There's this high pitched noise in the soundtrack and it's making my head hurt.

  40. Yep, linear tape is still a popular format. The most common format these days is LTO, or Linear Tape-Open. Modern, generation 7 LTO tape carts can hold up to 6TB of uncompressed data, with 12, 18 & 48TB capacities on the horizon. LTO cartridges have only one spool, so the tape drive contains a take-up spool internally. Data is written on the first track from the beginning of the tape to the end, then written on the second track from the end back to the beginning. Data continues to be written in this serpentine fashion until all tracks are full, and the tape has been wound back into the cart.

  41. Back in the day, I worked on a PDP-11 system which employed a TU-58 tape drive. The media was "block structured". These tape drives were also present on all VAX-11/730 machines to load the microcode during boot.

  42. Would have been interesting to know how the data is actually read and wrote to the magnetic media. How it physically reads the disk I think most people already knew.

  43. I grew up actually USING those, like, to store things on.
    I had a bag of 3,5s with loads of little applications on that I brought to school so I could mess around with them on the public workstations during recess… =p
    And before that I had a C64 with a floppy reader, my parents didn't have enough money to buy me a Super Nintendo so they got me one of those instead (Just kidding, I had a Sega Genesis too =p).
    Here in Europe the 3,5 floppies were called diskettes and the larger ones were called flex disks though.

  44. So basically, file allocation tables are literally bits of data that tells the computer where on the physical disk to look for the information in an actual file?
    I don't think I never really understood that until now.

  45. the large floppys are great for storage. specially for cd's.
    I hope to see videos about optical and flash storage

  46. Oh god I can hear the CRT displays. Even through youtube's compression, the audio capture, and my speakers, i can still hear them…

  47. My lab partner worked at NetApp, said they've only replaced their tapes archives a couple years back…gotta ask why? Is the speed differential between magnetic and silicon storage not drastic enough to justify the replacement price? We still got hard disks on the market so I presume the answer is yes, just wondering if there's anything in the future of magnetic storage, or if SRAM will eventually absolutely replace it….

  48. Strange that the floppies didn't originally have cases.

    Looks like something has gone wrong with that Apple II in the background towards the end.

  49. That tape holds 170 megabytes, not so much by modern standards. The nine tracks store eight bits and parity so it is not like one reads first one track, then another.

  50. am I the only one who didnt understand why the inner portions store the same amount of data as the outer portions?

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