GoKawiilMartyPC Developer Extracts NEC V20 Microcode via Die Photography
The developer behind the MartyPC emulator commissioned a 5.6-gigapixel die photograph of an NEC V20 CPU (fabricated by second-source manufacturer Sharp) to extract its microcode. The goal is to replace MartyPC's existing V20 emulation core, which was essentially a modified 8088 core rather than a true cycle-accurate model, with one based on the chip's actual internal logic.
GoKawiil's interpretation of the reporting above, not reported fact.
Cycle-accurate emulation of vintage CPUs like the V20 matters for retrocomputing preservation, enabling software and games from the era to run with perfect timing fidelity rather than approximations. This effort follows the precedent set by reenigne's 2020 8088 microcode decoding, showing how die-level reverse engineering continues to push emulation accuracy forward for classic hardware.
- A high-resolution die photo of an NEC V20 (Sharp-made second-source chip) was captured to read its microcode directly.
- MartyPC's prior V20 support was not cycle-accurate, essentially reusing 8088 timing logic.
- Microcode bits are identified by spotting transistor gaps in the polysilicon layer beneath the metal interconnects.
Source: martypc.blogspot.com — Visit Profile, 2026-09-04
Published there as: “Decoding the NEC V20 Microcode”
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