z386: An Open-Source 80386 Built Around Original Microcode

Small Things Retro Retro gaming and computing experiments by nand2mario Home Projects z386: An Open-Source 80386 Built Around Original Microcode May 23, 2026 by nand2mario This is the fifth installment of the 80386 series. The FPGA CPU is now far enough along to run real software, and this post is about how it works. z386 is a 386-class CPU built around the original Intel microcode, in the same spirit as z8086. The core is not an instruction-by-instruction emulator in RTL. The goal is to recreat