*Purportedly* an actual 720 ROM image of HPC2000. It's apparently been kicking around since 2006. Sent to me by Karpour, sent to him by Jax Coldwolf, obtained by him from person called "cmonex" in 2006. I have no idea where it came from, but it at least appears genuine.
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Snake-eyes on that one, sadly. I put a few printfs into the 32-bit and 16-bit read and write functions in the event of a misaligned read or write, none are ever printed.
So far I've worked out that there seems to be some list of tasks that need to be completed in order to bring up the system, which is sensible enough. Once the kernel is brought up, there's a function with a check at 13E2C (virtual) of R3, then at 13E30 it loops back if it's > 0.
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R3 starts at 0x12 on entry to the function and gradually decrements as various bring-up tasks are completed (based on observing kernel calls and reads/writes to hardware registers). R1 increments, but at a strangely different rate. R3==3, R1==0x10 seems to be the failure point.
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Interestingly, if I set MAME's debugger to break on that condition (R15==0x13E2C, R3==3, R1==0x10), then force R3 to be 0, it continues starting up, though I have to figure it's doing so in an unstable state.
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