Z386: An Open-Source 80386 Built Around Original Microcode

The z386 project implements an Intel 80386 CPU on an FPGA using the original i386 microcode, aiming for archaeological accuracy rather than peak performance. Built by nand2mario (who previously created a similar z8086 project), it runs on Altera Cyclone V and Gowin GW5A FPGAs at roughly 70 MHz equivalent speed. The approach guarantees close compatibility with original hardware behavior, handling complex features like memory management, paging, protected mode extensions, and register debugging. It can run real software including DOOM, though its 16 kB cache limits cycle efficiency compared to original hardware.