Core16: Interactive Core Memory Made Smaller

Core16 makes it easier to get started weaving your own Interactive Core Memory. You can do a lot of fun stuff with it after it is assembled!

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Core16 is inspired by Core64. It is designed to directly support educational opportunities in the world of STEAM (Science, Technology, Engineering, Art, Math).

By reducing the number of cores, physical size and PCB layers, I've reduced the cost and time required to weave your own Interactive Core Memory. Core16 is the size of a U.S. business card.

Core16 maintains the same interactive characteristics of the larger Core64 and Core64c kits. It makes core memory even more accessible to those who aren't able to take on the larger versions of the kit. It will be fully interconnectable with the Pico W... when you or I get to implemented some mesh capability!

This project was introduced as a workshop at Supercon 2023.

Core16 features include:

  • Size of a common business card
  • Core matrix is 4x4 and includes RGB LEDs on the bottom side of the board for each Core of memory.
  • All components are mounted to a single PCB.
  • Fully controllable and addressable Core Matrix and LED Array.
  • Includes Raspberry Pi Pico W (can you help mesh these with Wifi or BT?)
  • Four magnetic touch buttons.
  • Two magnetic stylii included.
  • Powered by USB cable.
  • Battery back frame, dual style holder, and lanyard attachment loops.
  • A complete single page schematic will capture the entire system to make it easier to understand and learn from.
  • Firmware will be compatible with the same firmware as Core64 and Core64c, however the available functionality will be reduced in accordance with the reduced availability of Cores and LEDs.

This will be open source... right now I'm busy getting the "core" project work done. I will circle back to share the source files in Github before the end of the year.

  • The Big Test Fixture

    Andy Geppert10/25/2023 at 04:08 0 comments

    This is the test fixture I had in mind when I started this project:

    It mostly works... I made all the interconnections with individual wires. Gross. The next iteration will be a proper PCBA with pogo pin receptacles, and nice reliable traces running from the DUT to the Core Test Matrix. The biggest challenge is the extra resistance in the wires to the Core Test Matrix, making that part of the system unreliable. Everything else works great. I'm very happy with the mechanical moving bits:

    Here's some of that nasty wiring:

    Did I mention wire harnesses are a time suck?

    A lot of my learning and inspiration came from these guys:

    This video highlights the challenges in designing these things... 

    ...and justifies why it's worth paying them for the service!

    Nonetheless, my fixture did help me get through testing all the boards, so now I can move on to kitting everything for the workshop!

    Oh, and finish the firmware...

  • Core16 Kit Contents and Frame

    Andy Geppert10/13/2023 at 03:43 1 comment

    Workshops for Supercon 2023 were announced today and this project is one of them!

    Here's a preview of what is in the kit:

    Frames are in production to:

    One hour and 20 minutes per frame set... But I'm very happy with the result which is easy to print (no supports) and snaps together in a very satisfying way. There are lanyard loop attachment points at the top corners, and from the front, the frame is minimal.

    The backside of the frame holds the battery pack and a pair of stylii.

    And it stands up on it's own too:

    Suitable as a desk clock!

  • Introducing SAO OLED!

    Andy Geppert10/11/2023 at 03:51 1 comment

    Every project needs a display, buttons, and a command line! Here's the display solution I've come to appreciate:

    I've been kicking this idea around for awhile and now it's a reality! These will be available on Tindie in November '23 as a DIY kit. Features and included components:

    • PCB
    • OLED 128x64 Display 0.96" with 0.1" 4-pin header I2C
    • Supporting stand-offs to secure OLED screen
    • Solder jumpers to choose polarity to ensure compatibility with the common I2C OLED displays
    • SAO plug (bottom)
    • SAO socket (top) to extend to more SAO stuff
    • QWIIC Socket

    Naturally, all of my recent Interactive Core Memory kits are compatible with this and make use of it, if it is connected.

  • Test Fixture, not what I wanted to use...

    Andy Geppert10/10/2023 at 03:05 0 comments

    Here's the "functional" test fixture currently being used for production testing:

    This falls short of the bar I set initially. But the "real" test fixture still needs some electrical debugging. Something about the core sense signal is be thrown off, and I haven't been able to figure that out yet. But I will get it solved soon! I've diverted to a frame to hold the completed Core16 kit. Look for that in the next project log update.

  • "I Am Completely Operational, And All My Circuits Are Functioning Perfectly"

    Andy Geppert09/21/2023 at 01:43 0 comments

    The Core16 prototypes are alive and well! Everything is working correctly. Even so, a few tweaks and silk screen corrections were in order before releasing a larger batch for a pre-production build. While the boards are being fabricated, I'm working on creating a robust test fixture to streamline testing. For the other Core64 kits, I've been using this contraption I slapped together. Reliable isn't a great word to use when describing it.

    Alas, design and assembly time was short.

    This time, I kick started the Core16 test fixture by ordering one of these kits from Amazon:

    I know I'm in for some assembly adventure, but it should save some time and provide a good base to work with. This might be my first and last DIY fixture. I've learned a lot from the guys at through this video. Still, I'm gonna give the scrappy method a chance and creatively consume some junk drawer inventory. And it's all brought together with some 3D printing, of course. But the results are encouraging so far.

    That's the moving plate. Seems good enough to move forward with. Now, on to the probe plate with the VERY IMPORTANT integrated power switch! See video linked above if you want to understand the nuances of test fixture design and why a switch is important.

  • Prototypes in hand!

    Andy Geppert09/05/2023 at 03:31 0 comments

    The prototypes are here!

    These are 4 of the 5 that were assembled with the JLCPCB service. I had to add the LEDs and four hall sensors since those weren't available with their service. And that is the fifth one show here:

    All the LED and I2C circuitry works at this point. Whew!

    And that's what it looks like when 16 bits of core memory are woven in place over the LEDs. As expected, it went much faster than 64 bits. I have a design for the screen protector (a must!) but I plan to leave the LEDs exposed without a diffuser layer. Because each pixel is already in its own little well, they look pretty good as is. The well also provide a place for the Core Memory to sit just below the surface of the PCB so they are slightly protected.

    Now I'm working on the firmware, adapting it from 64 bits/pixels down to 16. Even though it's not all complete, it already looks eye catching with the RGB LEDs. 

  • Core16 prototypes ordered!

    Andy Geppert08/28/2023 at 03:46 0 comments

    Finally hit the order button. I went with the quickest possible turn-arounds at JLCPCB, which means a bland green PCB. Makes a fine first prototype that is bound to get hacked up as I discover mistakes and make tweeks. It's already in production. And my Digi-Key order is in as well for the components I need to manually add to the prototypes (LEDs, Hall Sensors, battery pack). Here's the confirmation render for part placements that I received. 

    Looks good!

    Next step is a simple 3D-printable battery case holder so it'll snap on to the back of the board.

  • Final design checks before prototyping

    Andy Geppert08/26/2023 at 03:16 1 comment

    I'm very close to prototype release! I need to do some final schematic Ref. Des. # checks this weekend and it should be good to go with a very high confidence of the prototypes working. I'm trying to check and avoid all the mistakes I've ever made before... I know it still won't be perfect but it will close!

    I'll need to assemble the LEDs myself, and the core matrix of course. But I expect assembly is going to be lighting quick compared to Core64. The reduced component count makes a lot of things easier.

    Component availability looks good for everything. Knock on wood. Digi-Key should expect to hear from me Sunday!

View all 8 project logs

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Anders Nielsen wrote 08/25/2023 at 06:24 point

Yay! Fewer cores! Decreasing the barrier to entry is always a good idea. I'm still dreaming of interfacing core memory with a 6502 project but time certainly isn't on my side. 

  Are you sure? yes | no

Andy Geppert wrote 08/26/2023 at 02:51 point

I hear ya. When I get to driving one of these core memory projects with a 6502 it will be via my EMMA II which is a 6502 trainer. It has a nice row of 16 IO lines, designed for expansion. I'm very excited about the Core16 right now though, so full steam ahead!

  Are you sure? yes | no

Anders Nielsen wrote 08/26/2023 at 08:34 point

More core... I mean less cores! Go go go! :D

  Are you sure? yes | no

Andy Geppert wrote 08/21/2023 at 19:05 point

Yeah, I think this could be extremely popular version. It's also an experiment to see if it inspires a re-spin of Core64 into a single board. Reducing board count could be a big deal for people. Hoping to demo this version at VCF Midwest 2023!

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Tom Nardi wrote 08/21/2023 at 17:32 point

Very exciting to see this move into a smaller form factor, lots of interesting possibilities.

  Are you sure? yes | no

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