Decoding the NEC V20 Microcode
reenigne's decoding of the 8088 microcode in 2020 opened the doors for extremely accurate emulation of the 8088 CPU. Although I had added support for the NEC V20 in MartyPC, the V20 core was not cycle-accurate in terms of the V20's actual timings. It was an 8088 in a V20's clothing - a copy-paste of my 8088 core with V20 instructions tacked on. This was not an ideal case, but the prospect of making my V20 core cycle-exact without the microcode seemed like it might be a discouraging slog of trial and error. So why not get the microcode, then? I recently commissioned InfoSecDJ to take die photography of an NEC V20 CPU (actually a second-source V20 fabricated by Sharp, but a V20 nonetheless). He did an excellent job. The NEC V20 CPU die - InfoSecDJ This photomosaic is extremely high resolution - 5.6 Gigapixels to be exact, an astonishing 70478x80672 resolution - too large to even fit in the JPEG image format! You can see the entire thing at full resolution he...