Precisely. Check for 'ETOS' at ROM offset $2C.
For now, we have no mechanism to detect EmuTOS version number.

Excellent job

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Superb!

I am just assuming at this point that whatever was accessed before the sound registers in EMUTOS is actually the issue and is then causing the sound register to malfunction after that cycle. This really looks like an EmuTOS bug :( Something writes the value $7747 at address $0000c7bc between EmuTOS...

As I understand from pictures: EmuTOS without Bus Errors has the same problems. So Bus Error behaviour on the hardware doesn't seem to be the cause. Let's focus on the last picture. sr=2700 means that interrupts are disabled, so the problem is very unlikely to come from interrupts. pc=0000c7c0: This...

Apologies, those low PC addresses are normal for EMUTOS*.PRG. Such EmuTOS-RAM lives at $1c04. I'm looking at disassembly right now with the addresses of your screenshots.

OK. NB: You don't need to go past the first panic(), because it is not supposed to crash at all. I'm still very puszzled that it can continue the boot after pressing a key at the panic screen... Very strange. So it crashes during snd_init(), which writes initialization data to the YM2149. Mainly, it...

Thanks for your tests, Exxos! Every time, pc=very low value, which seems abnormal to me. I still suspect a jump to a bad address. Also, there are strange values in A0: last picture contains the soundchip address, previous one MFP... stuff related to hardware, every time. I still have big suspicion a...

Damn. We will have to investigate that. I hope it's not an EmuTOS bug. However, I have never see such thing before.
Once again, be sure that no AUTO/ACC programs are loaded at startup. Best way is to tap Control key a the EmuTOS welcome screen to cancel all AUTO/ACC programs.