[mmastrac]

Did the microcode disassembly find any useful backdoors to read microcode without decapping?

[nand2mario]

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.

[NooneAtAll3]

there are several iterations of 386 and only one was disassembled

so there's still a chance