z386: An Open-Source 80386 Built Around Original Microcode
https://nand2mario.github.io/posts/2026/z386/Of course they tested Doom :-D
They might also run Linux kernel 3.7, that supported i386. Gray386linux is still maintained, and runs a patched 3.7 kernel.
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Question:
Are there today any 386 instances running somewhere in the basement to do some productive stuff, maybe processing only some controller data once a day?
I remember the link some month ago where that one small shop ran completely on an old Amiga (?IIRC, not sure, was linked here)
Around 98/99 I was involved in a small IT-management company serving SME around the region, we had a client producing distinct metal objects with a big press; this got feeded once a day with a 5.25 floppy from another machine with production data - and it was still in use while we had already ethernet/USB/3.5 floppies etc. :-D
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Did the microcode disassembly find any useful backdoors to read microcode without decapping?
Not really. The 386 does not have an interface to read the ROM direclty. Instead, it uses the Built-In Self-Test (BIST) to verify the ROM's contents. It's basically a checksum-like mechanism that verify the integrity of the CROM.
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