It turned out that Dezaemon had its (large) SRAM mapped in the wrong way for ages (maybe since the beginning?) and nobody reported earlier (IIRC) that it complained during selftest about a "S-RAM Break Down"

Thanks to PooshhMao's report, I finally got aware of that and I fixed it locally





will add it as soon as I understand if the glitches are due to some further mapping error...