[hatari-devel] Big problems with bus error on Falcon
Thomas Huth
huth at users.berlios.de
Sun Jan 17 22:08:15 CET 2010
On Sun, 17 Jan 2010 01:17:59 +0200
Eero Tamminen <eerot at users.berlios.de> wrote:
> Hi,
>
> On Saturday 16 January 2010, Thomas H. wrote:
> > > > This is address 0xff800A. According to docs it's unassigned.
> > >
> > > That's why I'm asking myself that on the real computer, reading
> > > (or writing to) an unasigned area does not generate a bus error
> > > as it does on hatari. (it's just a guess, I have no clue).
> >
> > Most unassigned adresses cause an bus error on real hardware,
> > however certain memory regions do not and simply "ignore" the
> > access. I think this depends on the address decoder of the
> > corresponding hardware area.
> >
> > > > Another strange thing : the game conquest stops with a bus
> > > > error at address $ff8901.
>
> I found by accident one more.
>
> I had based on previous experiments thought that MiNT only boots from
> a real HDD image, not from GEMDOS drive. However, I accidentally
> started a GEMDOS dir that had MiNT in it and it actually booted, kind
> of (MiNT started, XaAES didn't), when I copied the mint.cnf to a
> floppy.
>
> Main issue is that it thinks it's booting from A: although its
> booting from C: GEMDOS drive. Thomas, any idea what could be an
> issue?
FreeMiNT overrides the GEMDOS trap, so it does not work with GEMDOS HD
emulation.
> The thing relevant to this discussion is this (with GEMDOS tracing):
> GEMDOS Dsetpath("\mint\1-16-cur")
> GEMDOS: \mint\1-16-cur ->
> host: /home/eero/down/st/diskstuff/GEMDOS-HD/C/mint/1-16-cur
> GEMDOS call 0x9 (Cconws)
> M68000 Bus Error at address $fffa31.
> GEMDOS call 0x9 (Cconws)
> ...
>
> $fffa30-$fffa3f is also one of the unassigned areas in my
> documentation.
Did you really see a crash here (ie. 2 bombs or a corresponding
message on the screen)? I rather guess that MiNT probes for some special
hardware of the Milan or Hades or something similar.
Thomas
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