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Old 06 August 2014, 14:38   #21
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 20,651
Originally Posted by phx View Post
Ok, this is something I can try, when I have some more time. Maybe over the weekend.
Is it sufficient to run PPC code with M68k interrupt master?
Yes, m68k as interrupt master is better choice to mimic PowerUP (and WarpOS) environment. I think all code that sets PPC as interrupt master also stop the m68k.

I think at least following tests should be done:

- Does clearing bit 0 of REG_LOCK do anything at all? What if exact same sequence is done (write 0x85 to IPL_EMU four times, then clear REG_LOCK).
- Can P5_DISABLE_INT be modified when PPC is active. Nothing happens when I try to change it, bit always stays set. And does it really stop interrupts?
- Can M68K_IPLx values be modified. Don't seem to be possible at least under M68K CPU. (I assume they are always read-only)
- Does SELF_RESET actually do anything at all?

I also assume only phase5 and "official" p5 developers knew about that mysterious bit. For example WarpOS does not modify it. (At least I haven't noticed any accesses)
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