Decoding The NEC V20 Microcode ROM

A hobbyist project decodes the microcode ROM of the NEC V20 CPU, an Intel 8088-compatible chip, by analyzing a die shot image. Since the ROM contained nearly 30,000 bits, manual decoding was impractical, so the team used Travis Goodspeed's MaskRomTool to locate bits, then trained a convolutional neural network to classify each bit as 0 or 1 after manually labeling 1,000 sample images. The resulting microcode is being matched against the V20's internal architecture to understand its function, with progress tracked in a public GitHub repository. The work aims to produce a cycle-accurate emulator of the V20, whose microcode was historically the subject of a legal dispute between NEC and Intel over CPU compatibility.

Source: https://hackaday.com/2026/09/09/decoding-the-nec-v20-microcode-rom. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.