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Comment by golergka | Hacker News Reader

CPUs used in space are usually much simpler and slower than ours – they put enormous amount of resources on error correction due to radiation levels.

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I suspect the CPU in this satellite is a BAE Systems RAD6000, commonly used in NASA spacecrafts. It’s extremely expensive and also brittle due to the materials used. Very hard to get due to export regulations. I tried to source one of these CPU’s outside US once.

Wikipedia at least confirms that.

Do you mean brittle in the physical sense, like a potato chip? That's surprising; I assumed that a launch subjects all components to a fair bit of shaking around, not to mention the steday G forces.

If that's the case, it looks like the chip has a surprisingly modern feature set. For example, based on this article[1], the RSC on which the RAD6000 was based had an on-chip memory controller in 1992.

It also had a branch predictor, however, this line is notable:

> Note that the RSC never speculatively executes prefetched instructions.

This means that the branch predictor only did fetch/decode, and so the chip would not have been susceptible to Spectre, as the pipeline would have been flushed and the correct instructions reloaded as soon as the condition evaluated false, before the branch would have been actually executed.

[1]https://web.archive.org/web/20131004213712/http://zmoore.net...

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