Disassembling the 80386 Microcode: A Deep Dive into Intel's Processor Architecture

A technical blog post detailing the author's process of disassembling and analyzing the microcode ROM of the Intel 80386 microprocessor. The author describes receiving a high-resolution image of the microcode ROM from Ken Shirriff, the challenges of working with a 94,720-bit ROM (compared to the 8086's 10,752 bits), and the methods used to decode and understand the microcode. The post covers the architecture of the 80386's microcode, including the microinstruction format, control signals, and how the processor executes complex instructions through microcode sequencing.