z386: An Open-Source 80386 Built Around Original Microcode

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 recreate enough of the original machine that the recovered 386 control ROM can drive it. Today z386 boots DOS 6 and DOS 7, runs protected-mode programs like DOS/4GW and DOS/32A,..