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Notes on the Pentium's microcode circuitry

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180 points leotravis10 | 1 comments | 31 Mar 25 18:35 UTC | HN request time: 0.208s | source
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mmastrac ◴[31 Mar 25 20:47 UTC] No.43539796[source]▶
I'm surprised the microcode ROM and format hasn't been dumped already. Is anyone working on this?

EDIT: The later Atom processors were dumped, are there any similarities?

[1] https://x.com/_markel___/status/1262697756805795841

[2] https://github.com/chip-red-pill/glm-ucode

EDIT 2: Some Pentium Pro disassembly work: https://pbx.sh/pentiumii-part2/

replies(2): >>43540008 #>>43543707 #
1. eigenform ◴[01 Apr 25 07:07 UTC] No.43543707[source]▶
> are there any similarities?

Don't know about the format, but if you look thru old ITJ articles[^1], it seems like the "direct access" interface for reading out different memories exists on older Pentium parts too. Presumably, if it were possible to dump over JTAG, it would be at least a little bit similar to what Peter/Mark have already looked at on newer parts.

[^1: https://www.intel.com/content/dam/www/public/us/en/documents...