z8086: Recreating the Original Intel 8086 Processor Using Recovered Microcode
By
nand2mario
The bagel they save for the regulars. Don't skim, savour.
Summary
z8086 is a project that recreates the original Intel 8086/8088 processor core using recovered Intel microcode. Instead of manually implementing hundreds of x86 instructions, the core loads the original 512x21 microcode ROM and recreates the micro-architecture expected by that ROM. The implementation is compact and FPGA-friendly, using about 2000 lines of SystemVerilog, consuming around 2500 LUTs on a Gowin GW5A FPGA, and achieving 60 MHz clock speeds while passing all ISA tests.
Key quotes
· 4 pulledz8086: a 8086/8088 core that runs the original Intel microcode
Instead of hand‑coding hundreds of instructions, the core loads the recovered 512x21 ROM and recreates the micro‑architecture the ROM expects
z8086 is compact and FPGA‑friendly: it runs on a single clock domain, avoids vendor-specific primitives, and offers a simple external bus interface
Version 0.1 is about 2000 lines of SystemVerilog, and on a Gowin GW5A device, it uses around 2500 LUTs with a maximum clock speed of 60 MHz
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