Tindie
A retro 32-bit memory for Arduino using ferrite cores.
This is a DIY kit for building a 32-bit ferrite core memory. Magnetic-core memories were the predominant form of computer memory from the mid-50s until the mid-70s. They work by storing information into the magnetic field of a ferrite core. It is non-volatile, meaning that it preserves its contents even when power is turned off. However, this type of memory is power-hungry, requires a lot of space and needs to be protected from strong magnetic fields. Also the process of reading the memory destroys its contents so that every read must be followed with a write. To make a long story short, this is a hilariously impractical memory extension shield for your 3.3V / 5V Arduino. When you have completed building this kit you have your very own piece of computing history in your hands.
I built this kit because I am interested in retro computing and saw the memory shield project built by Ben North and Oliver Nash. However, sourcing all the components was quite painful; I had to order the cores from Bulgaria, check their characteristics and tune the construction based on my findings. I also wanted to fit all the components onto one PCB with through-hole construction - I ended up using a CPLD for all the address decoding logic. The project turned out so nice that I wanted to make it into a kit to make this interesting piece of vintage technology accessible for everyone.
The kit uses almost exclusively through hole components and anyone is able to put it together. It also includes programming headers and test points to support tinkering with the CPLD. The design software for the CPLD can be downloaded from Lattice's site for free. Full source codes are also published to encourage you to do your own experiments.
NOTE! Documentation is not supplied on paper with the kit delivery - please download it from my site before beginning.
24 bits of raw power
The documentation overall is great. I plan to use this as a demonstrator for teaching about computer memory. I think the tangibility of the cores make it easier to connect some of the concepts regarding a bit. I'm looking forward to seeing if we can flip bits using a small magnet.
The assembly instructions are sparse and there's a few pitfalls.
Assembly will require a good pair of tweezers and a magnifier. I recommend getting some strong reading glasses to ease the process.
Some pointers:
1) Pay careful attention to the wiring map of the memory array and the orientation of the cores. Orient the cores exactly as laid out in the wiring map.
2) C2 & C4 don't exist and are not included.
3) The parts manifest designates the difference between the two transistor types and their placement on the board. Fortunately one is even numbered transistors and the other is odd numbered so once you figure out which is which placement is easy.
4) When soldering components start with the surface-mount capacitors & resistors that mount on the back of the board.
5) When soldering transistors apply all of the odd numbered transistors, solder & clip them. Then all of the even numbered transistors. It gets a little hectic on the back of the board with all 48 leads sticking out and you can't really reach the contacts to solder them.
6) Use a few cm of the 32 ga wire to create a little tool. Loop it around itself and twist off in a spoon shape so you can grip it between your thumb and forefinger. This will make picking up 8 of the little cores simple(er) and you can then transfer them to one of the vertical wires easily.
7) The kit contains ample 32 ga wire. The cores thread much more easily on wire before the enamel is removed. When working with the horizontal wires leave a few couple cm of wire to work with on either end. After threading the horizontal wire use the soldering iron to burn the enamel. Cleaning the carbon off the wire is much easier than sanding the enamel.
8) Check as you go. As you solder each wire in place check the ends for continuity. The enameled wire can get trapped in the solder without making a connection.
9) Use the tweezers to pull the horizontal and vertical wires taut before soldering. This will line the cores up neatly which will greatly ease threading of the sensing wire.
10) The LED (D1) is unlabelled on the board for polarity. + is opposite from the arduino header.
Good luck!
Oh, one more really important thing. THANK YOU for both designing this and making the kit available. That's really a fantastic gift to the rest of us that you've put this out there.
A great product for the lovers of obsolete electronics
By the way, I tried to copy a MP3 to the core memory but failed at writing the file name... 32 bit (4 Byte) is a little bit tight... just kidding...
Response from the Seller
Rates to United States
| Shipping Rate | First item | Additional items |
|---|---|---|
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Finnish Post: Economy Mail
|
$4.80 | $1.50 |
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Finnish Post: Priority Mail
|
$8.00 | $1.50 |
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Finnish Post: Priority Mail with tracking number
|
$18.00 | $2.00 |
