[Andy Geppert] sends in his incredibly clever interactive core memory shield.
In a great display of one hacker’s work being the base for another’s, [Andy] started out with [Jussi Kilpelainen]’s core memory shield for Arduino. As he was playing with the shield he had a desire to “see” the core memory flipping and got the idea to add an LED matrix aligned behind the individual cores.
The first iteration worked, but it only showed the state that the Arduino believed the core memory to be in. What he really wanted was a live read on the actual state. He realized that an Adafruit Featherwing 8×8 matrix display also fits behind the core memory. Now the LEDs update based on the read state of the core memory. This allows him to flip the individual bits with a magnetic stylus and see the result. Very cool.
You can see a video of it working after the break.
That is SO COOL. I’ve never seen core-store actually in use, though I did once find a PCB with 1K of memory on it, 32×32 cores about 1mm in diameter. Beautiful board, the wiring was done with red-coated wire in one axis and green in the other so tilting it in the light gave you this awesome iridescent light show. Awesome work.
There’s a fantastic Smarter Every Day video with Linus Tech Tips where they go to a NASA museum and look at the core memory units used for Apollo flight computers, and talk to the guy who built it all.
Hmm, since my father has been dead for some years, I’d say that guy didn’t build “it all”.
Back in the day, my old man brought home one of the Apollo (back-up) core memory boards to de-bug (it was wicked cool looking!).
It was the day before a launch and he was stressed out because they couldn’t find the hard fault in this one core memory board and they didn’t want to scrub the launch.
He was up all night working on it and eventually found the problem, and my mom took him to the airport so he could take it to the Cape.
Those were exciting days.
While the cores in the old Univac 1206 were really too tiny to fool with back then the Juke Boxes had bigger ones. I’ve still got a vial of 50s vintage ones somewhere in the junkbox. (Explains why putting another nickel in the slot wouldn’t play the song twice – a one is a one no matter how often you write it.)
I’m gonna throw this out there in hopes that someone else takes it and runs with it, cuz I’m never gonna get around to it:
Flip-dot displays are basically core memory, minus the read-line, as I understand it. But you could probably weave such a line into a plane of flipdots. This gives you memory with an intrinsic read-out of the stored bits.
Now, we see [Andy] flipping bits with a magnetic stylus. My question is this: When the controller attempts to write back to the bit that the stylus is near, does the stylus twitch a little? If you perform repetitive writes and flips, can this be a form of haptic feedback to the person holding the stylus?
Would this then let you create a single device which is: Storage. Input. Display. And haptic feedback?
Neat. I like the idea of writing your program with a magnetic stylus.
Are there any Hall effect sensors that can report magnetic polarity? Some sort of weird 3 state switch?
Yes. Look up linear Hall device on ebay.
Now, an interactive memory shield with a mercury delay!
If you are interested, I’ve upgraded that 4×8 proof-of-concept to an 8×8 prototype: https://hackaday.io/project/166155-core-64-interactive-core-memory-badge that works very well now!