80386 Microcode Disassembled

This is an incredible piece of reverse engineering. Seeing the actual microcode implementation helps demystify how these older processors handled complex operations.

> ...they mentioned that it would be interesting to get high resolution images of the 80386 die and try to extract the microcode from it.

Can someone explain how is that from a high resolution image of the die the microcode can be reconstructed? I'm really curious, what's the process? Is the output some sort of Verilog? Does the process involve recognizing each and every transistor and model a circuit from that? I'm fascinated that something like this is possible at all...

I checked reenigne's blog a few days ago. "Hmm, nothing posted since 2020. Oh well."

It's especially fun seeing his blog going back 33 years.

I wonder if an OpenFletcher[1] would be able to get such images

[1]: https://openflexure.org/projects/microscope/

Here’s a great book explaining microprogramming from ground up: https://www.amazon.com/Computation-Structures-Optical-Electr...

Easy to find a free pdf

Meanwhile the original ARM didn't use any microcode at all.

For me, this is peak Hacker News. I am happy I took the hard courses at uni to understand a post like this. I’m also happy that HN was there to stimulate this thinking at the time (2015). Even if I now don’t really do anything with my humble knowledge of low level programming, every time it feels consciousnesses enriching. And it’s an awesome feeling.

For people that don’t have access to a uni, I recommend nand2tetris.org

The black box analysis needed to decode this is incredibly hard but also incredibly fun and rewarding to pull off. Very impressive work.

If you put this into an emulator, would it boot linux?