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Comment by VladRussian2 | Hacker News Reader

it is just ferrittes strung on copper wire lattice, no component to "break" until it is really physically broken.

What i've been wondering for many years about is why such schema wasn't miniaturized? We have disk plates with high density in HDDs, and the magnetic head is physically moving. Imagine if instead of the magnetic head there would be a [miniaturized] lattice similar in principle to the one on this image http://sovietsouvenirs.com/catalog/images/ic/core_memory-15-.... The similar principle is used in flash memory, yet in the flash memory it is electrons trapped in the floating gate instead of magnetic domains with all the problems (durability, sustained write speed) of flash vs. magnetic disks.

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Rust is still a problem with those little ferrite rings, though.

Depending on the environment you maintain for this device, it can actually be pretty delicate. I have some old (~25 year-old) electric motors, where the magnetic properties of the bigger ferrite rings have been degraded by rust. I guess it probably depends of the quality of the piece.

This means there could be one tiny rusty ring in one of the center planes, and that would effectively result in a bad block that exhibits inconsistent behavior for that single bit. A person would have to test for that. It could be programmed around, and you could still have a fully functional object, minus one byte or word (or bit, depending on how you approach it).

You'd also want to keep it free of dust, since dust CAN be metallic, magnetic and conductive. The item for sale looks like it's been taken care of nicely!

Since it's "solid state" (none of those parts move, do they?), I don't see why you need to leave it exposed to the outside air. Could you just cast the whole thing in plastic, or would it overheat? Maybe a mineral-oil bath?

The permeability/permittivity of the surrounding substance probably needs to be accounted for. I find it quite feasible that mineral oil (or plastic) would attenuate and/or slow down the changing magnetic fields.

From wiki: "A typical magnetic region on a hard-disk platter (as of 2006) is about 200–250 nanometers wide (in the radial direction of the platter) and extends about 25–30 nanometers in the down-track direction". It's not trivial to say "Let's get X and miniaturize it to this scale".

Flash memory uses standard semiconductor techniques, and HDDs simply employ platters with tightly controlled properties.

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