
One Bit Ferrite Core Memory - peter_d_sherman
https://sites.google.com/site/wayneholder/one-bit-ferrite-core-memory
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owenversteeg
This is pretty cool by itself of course. But I'm wondering, is there any
reason at all to use core memory today? I know EMP/disaster resistance has
been said in the past, but a small modern durable chip encased in a bunch of
protection should work better right?

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VLM
The only competitor core has for eternally non-volatile low tech near
radiation proof infinitely rewritable electrical data storage is latching
relays and each bit of latching relay is huge in comparison to core. Also
latching relays unlike core has moving parts that will eventually wear out. A
million cycles sounds like a long time for a latching relay to live, but as a
register or memory for a computer at 0.1 Hz thats only two months or so. So if
you want to use latching relays you're limited to applications where the
system will never perform more than a couple hundred thousand bit flips.

The marketplace for eternally non-volatile low tech near radiation proof no
moving parts infinitely rewritable data storage is roughly nil, unfortunately.
Maybe a space probe to the worst parts of Jupiter or as part of a nuclear
missile warhead.

"In the old days" they had to make the ferrite cores, then characterize them,
then wrap them into memory units by hand, but I would imagine given enough
money one could find a way to 3-d print cores around taut stainless steel
wires then fire the core ceramic, automating the process. Given a very large
budget of course.

Its probably cheaper in practice to ship very large amounts of flash wrapped
in lead shielding.

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hwillis
>The only competitor core has for eternally non-volatile low tech near
radiation proof infinitely rewritable electrical data storage is latching
relays

except for tape

>The marketplace for eternally non-volatile low tech near radiation proof no
moving parts infinitely rewritable data storage is roughly nil

incidentally google is the biggest buyer of tape in the world

>I would imagine given enough money one could find a way to 3-d print cores
around taut stainless steel wires then fire the core ceramic, automating the
process.

you are describing tape and it's predecessor wire recording. Rather than coat
a wire in magnetic material they just used steel wire. They only use ceramic
to make core because it's easier to fire it in an annulus than to punch out
laminations that small

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VLM
You bring up a fair point but tapes not really infinitely rewritable. You can
take something like a 60's PDP-8 and write a byte of data to the same core
address 333 thousand times per second for at least half a century and it'll be
fine. In my head that's a 14 or 15 digit number of writes which no tape or
even flash memory can withstand.

In theory much like a hard drive head floats on an air bearing over the
platter it should be possible given enough development time and money to make
a tape head that floats and never quite touches tape. I worked at a place in
the 90s that had IBM floating tape transport where compressed air maintained
some loops bouncing in channels to make sure the tape was never snapped taut
and therefore stretched but I'm taking about actually floating a non-contract
head which AFAIK has never commercially shipped for tape (although it would be
cool to be proven wrong).

I was going to bring up how tape can throw oxide after a couple decades in
storage but I suppose core could have dissimilar metal corrosion over the
course of a century or maybe temperature cycles would stress and crack
individual cores after a couple centuries unless kept at a constant temp. Also
in theory non-archival core could exist just like non-archival tape definitely
exists. So fair enough on that account.

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RugnirViking
I really like these kinds of practical demonstrations of how technology
worked. Its such a shame that an up-to-date version could need scanning
microscopes to see visually

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sengork
I know that this is entirely off-topic but I wish Google made their services a
lot more visible than they are. For example I completely forgot about
sites.google.com until I saw this link and the service has been there since
~2009.

~~~
meowpants
[https://www.google.com/intl/en/about/products/](https://www.google.com/intl/en/about/products/)

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13of40
I've never seen "live" core memory. Anyone know how it stands up to physical
shock? For example, if someone accidentally bumped the rack, could it cause
some of the bits to flip?

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PopePompous
I used core memory in machines during the 1970s (primarily Data General
Novas). There was no problem with physical shock, but we did get errors during
strong thunderstorms.

Back then, when I was in highschool, I was told that the density of core
memory was limited by the dexterity of the Filipina workers who threaded the
wires through the tiny magnetic donuts.

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Fjolsvith
I used to be an electronic technician (305x4) in the Air Force and spent 3
years on one of the old 490L Overseas AutoVon phone switches right before the
DOD phased them out in 1987. This telephone system originally had a ferrite
core memory and it was NOT non-volatile. Every few milliseconds the system had
to run through each bit reading them and then re-setting them, as the magnetic
field collapsed over time. The system used 50 volts.

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flavio81
Obligatory quote from "Real Programmers Don't Use Pascal":

 _Your typical Real Programmer knew the entire bootstrap loader by memory in
hex, and toggled it in whenever it got destroyed by his program. (Back then,
memory was memory -- it didn 't go away when the power went off. Today, memory
either forgets things when you don't want it to, or remembers things long
after they're better forgotten.)_

[http://web.mit.edu/humor/Computers/real.programmers](http://web.mit.edu/humor/Computers/real.programmers)

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kwhitefoot
Brilliant work!

