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Comment by tectonic | Hacker News Reader

This reminds me of this short piece about debugging a live Saturn V (http://www.zamiang.com/post/debugging-a-live-saturn-v), and also a detailed video about the Saturn V's Launch Vehicle Digital Computer (https://www.youtube.com/watch?v=6mMK6iSZsAs) — it had 112 KB of dual-redundant hand-woven magnetic core memory.

(Links borrowed from my weekly newsletter about the space industry called Orbital Index https://orbitalindex.com — check it out if you like this kind of nerdery.)

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> it had 112 KB of dual-redundant hand-woven magnetic core memory.

Purely out of curiosity, do we know the amount of memory a modern orbital rocket like the Falcon 9 has?

640K

You might find this question interesting:

https://space.stackexchange.com/questions/9243/what-computer...

> The Falcon 9 has 3 dual core x86 processors running an instance of Linux on each core. The flight software is written in C/C++ and runs in the x86 environment.

It's unusual that x86 and Linux, which are generally not considered to be reliably and robust under an extreme environment, are used here. But since it's developed by SpaceX, it makes sense - move fast and break things, use off-the-shelf commercial systems as the basis to reduce costs.

Anyway, I think it should be more interesting to compare it with a modern rocket that uses a more specialized computer system, VxWorks comes to mind.

It's a risk assessment tbh; if they can put in more redundancy instead of fault-tolerant hardware at a fraction of the cost then it'll be cheaper for them.

I mean compare it with mainframes vs cloud computing; with the latter, you use off-the-shelf hardware and build your software in such a way that you will randomly lose machines, BUT because cloud computing you'll automatically spin up a new machine in that case.

> This reminds me of this short piece about debugging a live Saturn V

Fantastic link, thank you for sharing.

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