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Yea - I sure could use a bench microscope - but I dug up this little snippet from my live stream weeks ago (in case you missed it) which shows the beauty of a vintage magnetic core memory board up close. Thanks to viewer Jeff for sending that beauty in to the Lab!
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By Fran

16 thoughts on “Core memory board”
  1. Avataaar/Circle Created with python_avatars Perry Taylor says:

    Such a cool person. How am I just now finding out about this channel? Love what your doing here! Keep it up, you are awesome, don't let anyone make you feel otherwise.

  2. Avataaar/Circle Created with python_avatars Doctor Forbin says:

    thx fran

  3. Avataaar/Circle Created with python_avatars jsl151850b says:

    I bought a 2" x 2" panel at the Boston Computer Museum in the 1980s. It's around somewhere. (For Display Only)

  4. Avataaar/Circle Created with python_avatars Stephen Doyle says:


  5. Avataaar/Circle Created with python_avatars Jeff N says:

    It's like looking at a prehistoric fossil ancestor of my laptop.

  6. Avataaar/Circle Created with python_avatars Robert Allen says:

    Shirt and sweater, that's a little better except I think maybe she's playing with that thorium way too much. Anyhow yikes

  7. Avataaar/Circle Created with python_avatars Charles Kinzer says:

    At the university I attended I helped disassemble an old Burroughs tube type computer that had some core memory. I think the core memory mainly held the boot program. This thing also had a memory drum nearly the size of a 55 gallon drum. Quite a beast.

  8. Avataaar/Circle Created with python_avatars Bytor says:

    I have a magnetic memory core from a Atlas missile, if I remember it correctly. And, when I worked on the Carousel IV Navigation system, it used magnetic core and was in active service as late as the early 2000's. Hard to beat it for rad-hard memory at the time.

  9. Avataaar/Circle Created with python_avatars Capolaya says:

    When I was studying electronics a friend and me went to this market street where you could buy components and old stuff like tv parts, old mainframe computer boards dissasembled to the last screw and it was a common sight to find a core memory bank of just a few bits. Now these days are long gone and I wish I purchased one, for history's sake. Then I was just a student with little money to spend.

  10. Avataaar/Circle Created with python_avatars Bozo's Playhouse says:

    I woke up some old modules in the early 90's that still had data from when it was shut down, they were from a server used in a financial institution at one time.. I think they were 4kBytes per card. Similar setup as you've shown with the sense amplifiers and drivers on the same card.. I was intrigued with them ever since I was given an early HP calculator that used "magnetic bubble memories" -which are a different animal, because of the serial access methodology rather than random access with a read/refresh. I think HP even played with the acoustical serial memories as well or the early dynamic memories that used charged capacitors and fets. Growing up in the pacific northwest in the 70's was a godsend!

  11. Avataaar/Circle Created with python_avatars Ibanez Lefty Club says:

    Weird to see ICs and core memory, you would think the tech was much further apart.

  12. Avataaar/Circle Created with python_avatars Jerry S says:

    That module has 18 arrays of 512 bits. IBM had a parity bit with each byte to check for errors. Your module is 18 bits wide so it stores/fetches two bytes at a time. Your module stores 1 kilobyte. If you count the wires to each array there are 16 by 32. Looking at your module at 50 seconds into the video. The 8 transistors between the 4 ICs will be the 4 drivers for the 16 lines (2^4=16). The 18 transistors clockwise are the 5 drivers for the 32 axis (2^5=32). The groups of 16 transistors at the left and bottom are switches, on the other end of the wires from the driver. Been a long time since I worked on a core memory, and never worked on a Cambridge board. Buried somewhere in that are 18 sense amps, and 18 inhibit drivers. I worked for a couple of memory manufacturers. We made a similar size module with 64 by 128 arrays, 4096 by 18 or 16 Kilobytes. 16 modules in a bucket that fits in a 19" rack for 256K per bucket. 4 buckets in a rack for a megabyte. We could put 4 racks for 4 megabytes on an IBM S360/65.

  13. Avataaar/Circle Created with python_avatars reno lyons says:

    make a guitar pedal out of that thing Ha!!!

  14. Avataaar/Circle Created with python_avatars Varun Mehta says:

    I remember the first time I learned about core memory was from the docents at the Computer History Museum in Mountain View. We were a group of green little interns from Apple, and our eyes were opened to how ingenious folks were in the early days of computing.

  15. Avataaar/Circle Created with python_avatars Mark Volstad says:

    I used to repair core memory boards back in the 70s. The usual point of failure was a current driver IC. I wrote a memory test in Basic (natch!) that, based on the failing memory locations, would pinpoint the chip that had to be replaced. Fun times!

  16. Avataaar/Circle Created with python_avatars Jason Bryant says:

    that's incredible

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