Re: [hatari-devel] Hatari IKBD emulation regression?

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 05/05/2014 23:47, Eero Tamminen a écrit :

> > The problem is that when the game loads, it waits for motor to stop in
> > drive A (because it expects to run from floppy).
> > Just insert a floppy in drive A, and this will fix the problem.
>
> Thanks, yes, it does fix it.
>
> Why it works without the floppy in Hatari 1.6.2?

Because Hatari 1.6 was not accurate, and as this behaviour was not 
tested on real HW, it assumed led would turn off, which was wrong.

> I guess this relates to the "LED with empty floppy drives"
> discussion...

Somehow, but more generally Hatari was not accurate before on "special" 
cases when drive is turned off or drive is empty. I made a lot of 
measures with my STF to fix this and get the same behaviour as real HW.
Result is that led will stay on when you access a drive without a floppy 
(unless you implement an additional timeout, which most TOS/games don't do).
The FDC itself will not complete its commands until a disk is inserted 
(to be able to count indexes), during this time motor and led will 
remain ON.


> My personal opinion is that if there are different kinds of drives
> and their behavior, I would (at least by default) select emulating
> the one which makes things (like Puzznic) more likely to work and
> meets people's expectation (LED turns off when there's no floppy).

People expectations don't matter ;) What matters is to be as accurate 
and close as possible to a real ST (and to the most widely used models).

Apart from old 520 ST (not F), the behaviour is that led doesn't turn 
off (and I think that's the behaviour of all STF/STE models). And the 
led activity is directly related to emulating the FDC, which means you 
can't have a led that turns off (to be "good looking") and a correct FDC 
emulation.

The led is just a consequence of a correct emulation, this should be the 
default behaviour (in the same way that having "fast-fdc" per defaut 
would break a lot of copy protected games)

Now that Hatari will support copy protected disks like IPF and STX, 
there's no other possibility than to respect all the timings, even the 
tiny ones that look annoying to the user.


Nicolas