Re: [hatari-devel] _FRB cookie in Falcon emulation

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 01/08/2025 à 19:28, Uwe Seimet a écrit :
> Hi,
>
> after exchanging an email with Thomas things have become clearer to me. I
> understand the motivation for the _FRB change, but nevertheless there are
> accelerators with Fast-RAM where a patched TOS is optional. This also
> surprised me, but the information I got from a beta tester is very clear
> on that. Without a patched TOS you have to run a program in the AUTO folder.
>
> It's my fault that I missed this detail in the mailing list but I often only
> look at the topics and did not notice that there might be a change related
> to the _FRB. I would appreciate a respective note in the "Memory setup"
> dialog, so that Hatari's behavior is more explicit.
>
> After reading the current release notes I assume that Hatari does not
> modify the TOS 4.04 behavior wrt to setting _ramtop and _ramvalid.

Hi

just to be sure, can we consider that there's no regression introduced 
by the _FRB cookie in gemdos hd ? I agree with thomas that this cookie 
will only be added in the non standard case of TT RAM + falcon.

In the case of Hatari, this is done when Gemdos HD is used, so if you 
emulate a Falcon + tt ram, you can :

 - either not use gemdos hd and use other HD "low level" emulation, and 
in such case you need a program in AUTO to take care of adding such _FRB 
cookie as early as possible in the boot process (before accessing floppy)

 - use gemdos hd, which will add _FRB cookie automatically. In that 
case your AUTO program can certainly run too, either it sees _FRB is 
already present and does nothing, or it overwrites it with a new memory 
address in standard RAM (but hopefully this AUTO program will handle the 
case where _FRB cookie is already there and will not create a 2nd _FRB 
cookie...)


thomas : maye the lines in release notes should specify that _FRB cookie 
for tt ram will be created only when gemdos hd is used (ie cart_data is 
loaded) ?


Nicolas


> > Hi,
> >
> > > The cookie only gets installed when using TT RAM in Falcon mode. This is not
> > > a configuration that is possible with a real stock Falcon, since that only
> > > support memory up to 14 MB. The only way you could get something similar is
> > > likely a CPU accelerator like the MightySonic, and I assume those install a
> > > _FRB cookie, too. Otherwise your floppy disk access just cannot work in such
> >
> > No, accelerators do not necessarily do that. My beta testers are testing my
> > software with various hardware accelerators. This is why I stumbled over
> > this very recently.
> > There is not always a patched TOS version. This is why in one of these
> > setups a beta tester runs an AUTO folder tool provide for his hardware
> > that deals with anything related to Fast-RAM.
> >
> > Best regards
> >
> > Uwe
> > ~