Re: [hatari-devel] Accessing I/O memory on Hatari

[Thomas Huth <th.huth@xxxxxx>]

Am Wed, 04 Jan 2012 10:37:15 +0100
schrieb Nicolas Pomarède <npomarede@xxxxxxxxxxxx>:

> Le 03/01/2012 23:04, Roger Burrows a écrit :
> > Hatari allows reads to I/O memory in user state.  Real Atari
> > systems don't; you get a bus error.  This should be fixed for true
> > compatibility.
> >
> > Attached is a simple test program that can be run on Hatari and a
> > real ST/TT/Falcon to demonstrate this.
> >
> > Roger Burrows
> 
> Hello
> 
> Yes, I can confirm this is the case and should be fixed. I would need
> to check if it's a regression or if it was always like this in hatari.

It's not a regression, it was even worse in the past (even writing was
possible in user mode). I did some experiments with this in the past,
and I thought that I was able to read the IO registers also in user
mode:

http://sourceforge.net/mailarchive/message.php?msg_id=19622129

But maybe I also did something wrong back then (e.g. read the ROM
memory instead) ... I currently do not have time to set up my ST again,
so I suggest that we simply do the change suggested by Roger -- if it
is causing trouble we will see it quite quickly since affected programs
will then crash with a bus error.

 Thomas