[hatari-devel] New EmuTOS floppy code causes bus error on (Hatari-emulated) MegaST

[Christian Zietz <czietz@xxxxxxx>]

Hello,

CCing to Hatari-devel list, because there's a question to Hatari
developers below.

While doing some (unrelated) tests with EmuTOS on Hatari, I noticed that
when I run EmuTOS on an emulated MegaST, it crashes early during boot
with an bus error accessing $FFFF860F. It runs on an emulated ST, though.

This register is the floppy density selection registers ('modectl') that
is always been written to after Roger's recent changes to the floppy
code. This register exists neither on the ST nor on the MegaST. The
reason why this only crashes on the emulated MegaST is easily found: A
section of code [1] with a comment saying "Normal ST has two address
which don't generate a bus error when compared to the Mega-ST. Mark them
as void handlers here."

The comment is very specific, so I think this behavior has been tested
on a real MegaST. Can someone from the Hatari developers confirm this?

Alternatively: Can someone run a current EmuTOS snapshot on a MegaST? (I
don't have one.)

Probably EmuTOS's floppy code needs to be changed here.

Regards
Christian

[1]
<https://hg.tuxfamily.org/mercurialroot/hatari/hatari/file/2008051815e6/src/ioMem.c#l134>
-- 
Christian Zietz  -  CHZ-Soft  -  czietz@xxxxxxx
WWW: http://www.chzsoft.de/
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