Re: [hatari-devel] Mega ST(E)

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 16/06/2016 à 21:24, Thomas Huth a écrit :
> Am Thu, 16 Jun 2016 20:47:36 +0200

> > But in the TOS detection code, there's :
> >
> > $00fc1f72 : 307c fc20                          movea.w   #$fc20,a0
> > $00fc1f76 : 2429 0008                          move.l    8(a1),d2
> > $00fc1f7a : 244f                               movea.l   sp,a2
> > $00fc1f7c : 237c 00fc 1fb6 0008                move.l
> > #$fc1fb6,8(a1) $00fc1f84 : 117c 0009 001b
> > move.b    #9,$1b(a0)
> >
> > So I think TOS expects a bus error when RTC is not present and we try
> > to read fffc29, but here bus error won't happen. Or is there
> > something else ?
>
> According to tests/buserror/results/st_b.txt there is no bus error here
> on a plain ST - that's why the handler are set to VoidRead/Write
> instead.

Indeed, I tried it on my STF to be sure and there's no bus error when 
accessing to non existing RTC region.

Maybe TOS code for RTC is some kind of generic detection code (that 
would work when blitter is not there and gives bus error), but they left 
here for no reason ? Even in more recent tos 2.06, it still checks for 
bus error when accessing fffcxx, which is useless.

Nicolas