| Re: [hatari-devel] Small bug in Hatari Falcon emulation |
[ Thread Index |
Date Index
| More lists.tuxfamily.org/hatari-devel Archives
]
On 23 Nov 2020 at 1:08, Eero Tamminen wrote:
>
> On 11/23/20 12:47 AM, Roger Burrows wrote:
> > When the "STe Bus Emulation" bit (0x20) in the Falcon Bus Control Register
> at
> > $ff8007 is zero, "STe Bus Emulation" mode is set. This affects bus error
> > handling. Hatari already models this as far as the I/O memory area is
> > concerned (I haven't attempted to check how accurately yet). But it also
> > affects bus errors when accessing RAM, which Hatari does NOT model.
> Basically,
> > on a real Falcon with "STe Bus Emulation" enabled, there are NO bus errors
> > generated for the whole $0 to $dfffff region, even in user state. Even if
> RAM
> > isn't present at an address, no bus error occurs.
>
> Do reads to non-existing RAM areas produce some specific value like
> zero, or random values, or
A quasi-random sampling of values shows 0xff is returned. That looks like a
floating bus (but what would I know, I'm a software guy).
> is the target location value just unmodified?
>
I'm just doing reads, so I'm not sure what you mean.
Roger