Magnetic core memory USB drive transfers files in sneakernet first — text and image files get moved between PCs via hugely constrained archaic memory tech

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An attached LED array shows the live status of each magnetic core.

PC-to-PC USB magnetic core memory tests.
(Image credit: @dydt_Nao on Twitter)

A homebrew dinner-plate-sized magnetic core memory USB storage device has been used to transfer a text file from one PC to another for the first time. In what is “maybe the world’s first” [machine translation] Japanese researcher @dydt_Nao indicates they successfully used their retro-modern flash drive as a sneakernet device. We covered this space science researcher’s earlier efforts to rekindle this archaic computer memory tech back in February of this year.

Back in February we noted that this USB flash drive had some severe shortcomings, but was nonetheless an effort that we warmly applauded. There were three key drawbacks to this ungainly USB flash drive. Firstly, it is rather massive, and it looks roughly a foot (30cm) square. Secondly, by contrast, its storage is incredibly tiny at just 128 bytes (not GB, MB, or even KB). Lastly, according to our understanding of the technology, the data stored gets erased during the read process.

In the tweet-embedded video we get to see the unnamed USB Type-A gadget work its magic. Interestingly, as data is read to/from @dydt_Nao's device, LEDs in an attached 32 x 32 array glow a vivid red. Every LED corresponds to an individual magnetic core. We see Windows reporting the drive as having a 6.5KB capacity, but that is likely something to do with the Raspberry Pi Pico being used as an onboard controller. Towards the end of the video we get to see that the text has been successfully transferred from the drive to Notepad.

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Not content with a mere text demo, @dydt_Nao follows up with a BMP image transfer. Monochrome bitmaps up to 32 x 28 pixels can be stored on this device. Perhaps a little of the limited device memory space (32 x 4) is used up by the image file header.

You can read more about magnetic core memory in our article commemorating the 75th anniversary of its patent filing by inventor and MIT electrical engineer Jay Forrester. Magnetic core memory earned its place as the dominant form of random-access storage in digital computers for two decades. Today it seems like a bizarre curiosity.

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Mark Tyson
Mark Tyson
News Editor

Mark Tyson is a news editor at Tom's Hardware. He enjoys covering the full breadth of PC tech; from business and semiconductor design to products approaching the edge of reason.

7 Comments Comment from the forums
  • psyconz
    At first, my thoughts were about how this has to be the most useless random hacky device that this website has ever listed. Then I thought, well, how many erase-on-read devices have I heard of before? That could actually be useful. Then I realized we have them, actually, en masse, with destructive AI-training book scanning 🤣
    Reply
  • alrighty_then
    I enjoy articles about people bulding odd stuff because I don't seek this out or hear about it otherwise.
    Reply
  • psyconz
    alrighty_then said:
    I enjoy articles about people bulding odd stuff because I don't seek this out or hear about it otherwise.
    Yeah, I enjoy most of Tom's random "Quake on a satellite" or "LLM running on 50 year old hardware" stuff, but this one... 128 bytes. That's just an quantum-mechanically-small amount of storage. But I do appreciate the cool scientific, technical and creative side of this one.
    Reply
  • derekullo
    psyconz said:
    Yeah, I enjoy most of Tom's random "Quake on a satellite" or "LLM running on 50 year old hardware" stuff, but this one... 128 bytes. That's just an quantum-mechanically-small amount of storage. But I do appreciate the cool scientific, technical and creative side of this one.
    Each ASCII character / keystroke is a byte so it's essentially about half a twitter post ... 280 characters / bytes

    ^^^ That sentence alone was 116 bytes :P
    Reply
  • rluker5
    I've got one of those brown framed ferrite bead panels on my bookshelf. You can get them on Ebay, but they used to be a lot cheaper. Nice to see one put to use, about as much work as I expected. Would be neat to see someone using magnetic wire for data. Could probably hold a lot more for a longer time. I used to save data on cassette back when my parents had a TI-99/4a and you could likely use any sufficiently precise audio recording method to do the same. Data sounded same as an old phone modem.

    This guy has one for sale now: https://www.ebay.com/itm/318764798056?_skw=magnetic+wire+recorder&itmmeta=01M17M2AD13NVG97H04TAWVWAS&hash=item4a37dcd068:g:mVMAAeSwSUlqiJTh&itmprp=enc%3AAQALAAAA8GfYFPkwiKCW4ZNSs2u11xBa%2FWI%2BcH6mE%2BrqExfJm%2F4TV8lwAbcErcoJWyi242tr%2FsBfbY%2B9RECeA%2FWFKjsSnux8riFAnX3yMQSxlrMCTffo740kf%2BhT1Wj6PkI0auHzIODNnNiS5f730cSDzrH3vavG6R4guqR%2FVgwUAn0RRArDIPcsryLfnF2Um2zFZL6%2BEDBQTRQfW98WN3QNGZb6egK6U9zfRYbjN1KOJ08kYmlZ4lsmvnu789UCwfeEew4lZ0TNZGleCCmVWGMuCW%2FVnN2lw4sayb2%2BckTO3U%2B9laLbXRzAuA92z0qN9VNtaJofqA%3D%3D%7Ctkp%3ABk9SR-KmifSJaAhttps://i.ebayimg.com/images/g/mVMAAeSwSUlqiJTh/s-l1600.webp
    Reply
  • abufrejoval
    psyconz said:
    At first, my thoughts were about how this has to be the most useless random hacky device that this website has ever listed. Then I thought, well, how many erase-on-read devices have I heard of before? That could actually be useful. Then I realized we have them, actually, en masse, with destructive AI-training book scanning 🤣
    that might ignore the fact that reading from DRAM is also destructive... (the RAM chips make up for that on their own)

    And actually any page activation, whether for read or for write actually causes an overwrite afterwards, apart from the needed refreshes.

    Yes, it's a bit mind boggling, that core memory might store data for decades, only to have it's data destroyed on reading. But memory--of any kind--typically isn't forever.

    And actually the fact that stories now don't get to drift constantly with the retelling, is first, an anomaly in human history, and second, perhaps more of an issue than a benefit.

    Especially when some attribute more value to the written word than hearsay.
    Reply
  • abufrejoval
    The first PDP-11/34 I worked on (around 1983), started with 64k of core memory. That machine was perhaps a bit backward in terms of the underlying technology base with tons of TTL chips to implement the processor and controllers, instead of single chip CPU.

    But in terms of software RSX-11 was way ahead of anything microcomputers and PCs ran at the time, a true multi-user and multi-tasking OS, even designed for real-(enough)-time industrial control.

    Since we mostly used it to run a relational database (Datatrieve), it got upgraded to 256K of DRAM soon after: no more stopping and instant restarts of the machine in mid-flight!

    I seem to remember that one of the earliest luggable laptops, a Grid Compass 1100, used magnetic bubble memory (somewhat similar, not the same) for robust solid state block storage in 1982: it flew in the Shuttle.

    Columbia data could also be recovered after both the fiery explosion and after having lain in sea water for months: so there is something to be said for the technology.
    Reply