Decoding the NEC V20 Microcode

This blog post details the author's journey in decoding the microcode of the NEC V20 CPU, emphasizing the technical challenges faced during this process. It explains the techniques used for visual analysis of the CPU die, including die photography and machine learning for bit classification. The author shares hands-on experiences employing tools such as MaskRomTool and PyTorch, providing insights into both the practical and theoretical aspects of reverse-engineering microcode. Challenges and collaborative efforts with the Vintage Computer Federation community are also discussed, demonstrating the process of understanding CPU architecture and implementing the findings in an emulator.