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Fun fact: the actual programs in the spacecraft were stored in core rope memory, an ancient memory technology made by (literally) weaving a fabric/rope, where the bits were physical rings of ferrite material.


"Core" memory is resistant to cosmic rays. The state of a core bit will not change when bombarded by radiation in Outer Space. Can't say the same of solid state memory.

I worked on core memory computers in the 60's. You had 16K, tape drives (no disks) and FORTRAN. What a gas!

At a low level your correct, but you can use error correction and a lot of redundancy to prevent cosmic rays from corrupting solid state memory and still have a lot more than 16K of storage space for a long time.

...and radhard designs.

...which involve error correction and a lot of redundancy. But I assume you meant radhard electronics boxes, which lets you run whatever you want within a cosmic-ray shielded box.

you can do more than just improve on the boxing


Just curious how they knew this given how young the computing industry was at the time that this was used.

Were there some "Well, that's interesting..." moments where we launched something and realized it was affected by cosmic rays?

Hubble, the ISS and other low-orbit satellites are affected by the South Atlantic Anamoly, which funnels down charged particles from the Van Allen belts.

(This /was/ a surprise to the folks who designed Hubble, but the spook satellite people apparently knew all about it . . . and didn't tell the Hubble folks, not even over beer or something. Great win for national security, guys </sarcasm>).

I didn't see an opening bracket for sarcasm so I assume it's before 'Great win'. Were they really surprised by this? Also are they same people that didn't know putting hard drives in space would fail because of the lack of air and had to replace them with SSDs?

I think it's just an understanding of how the underlying physics work. Alpha and beta radiation will cause bits to flip in solid-state devices, because the state is held with electrons. Whereas core rope memory stores that state as magnetic fields in ferrite cylinders. So radiation will basically just bounce right off the giant ferrite cores (giant relative to solid-state semiconductors, that is).

*I am not a physicist, someone correct me if I'm grossly wrong.

Hmm, it's more like any ionizing particle (charged) creates pairs electron/hole, many of them, so that the charge distribution in the pn junctions are altered. Sometimes gamma photons generate Compton electrons in the material that act as delta rays, to the same effect. Heavy particles can alter the crystal structure, inducing defects that may change its properties. Magnetic storage devices don't have polarised junctions and could withstand all this if they didn't include solid state electronics. Radiation hardening techniques and shielding can help a lot.

Its more a cause of the radiation ionizing the underlying semiconductor material. For instance when an electron tunnels into a transistor it can cause strange effects. Look up single event upset and single event latch-up for more information. The SEL is interesting as it causes a transistor to act as a double transistor and start drawing tons of power. At least that's how I understand it.

My guess is that radiation's effects on solid-state technology was well-known from nuclear tests.

"Some programmers nicknamed the finished product LOL memory, for Little Old Lady memory."


In 1967, binutils was a person.

Huh? I don't get it.

Binutils are a set of utilities used by *nix systems.


the person who builds the core rope memory

Aha. Binutils = compiler, linker, weaver, ....

I think this is one person who can legitimately say that he programs with a magnetized needle and a steady hand. http://xkcd.com/378/

Great! Texting LOL to my grandmother suddenly has a whole new meaning. I love it! She often complains her memory is getting old so it works even better!

Related: Magnetic Core Memory, the read/write version of Core Rope Memory. http://www.corememoryshield.com/report.html

Sort of an interplanetary quipu.


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