[hatari-devel] Big problems with bus error on Falcon
Eero Tamminen
eerot at users.berlios.de
Sun Jan 17 00:17:59 CET 2010
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?
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.
- Eero
PS. Another interesting thing was that MiNT seems at boot read the (ini or
cnf) file byte at the time...
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