Re: [hatari-devel] a rare F030 incompatibility

Actually it's me who got it wrong :-)

It turns out Apex uses a bus-error detection to see if Expose is present. So in fact, Hatari is probably doing the right thing when reading that area.

I'm not sure yet why the prototype has this bug or why it appeared to work - but in any case it's not Hatari's problem so you can ignore my last msg...

On 16 October 2015 at 10:46, Thomas Huth <th.huth@xxxxxx> wrote:

On 16/10/15 10:52, Douglas Little wrote:
> Hi,
>
> I was testing some old stuff (a prototype version of Apex) and noticed
> that it won't run under Hatari - it throws bus errors immediately.
>
> The same program runs ok on my F030.
>
> Looking more closely, the the code is checking for a HW digitizer using
> an unusual address range:
>
> *-------------------------------------------------------*
>
> DIGICTRL = $FFF20000
> DIGIPAGE = $FFF40000
>
>
>
> I think this was the address space for the F030 Expose digitizer which I
> did support in a few programs.
>
> I don't know if anyone else still has one of these - or more
> importantly, how many programs will try to check for it - but it might
> be nice to make that space readable in supervisor mode, as seems to be
> the case on real HW.

It's unfortunately not that easy - we had a look at this a couple of
years before already, see:

http://dhs.nu/bbs-coding/index.php?request=3055

and especially:

http://dhs.nu/bbs-coding/index.php?request=3058

tl;dr: This address normally causes a bus error - just in Apex it works
for some unknown magic reasons.

Thomas