Re: [hatari-devel] falcon crossbar and ff8932

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Le 22/09/2016 à 16:39, Nicolas Pomarède a écrit :
Le 22/09/2016 à 10:25, Nicolas Pomarède a écrit :
Le 21/09/2016 à 22:20, Laurent Sallafranque a écrit :

When I coded the crossbar, I used another file that describes the
I haven't got any official doc for this, I did it by guessing the
behaviour and with the help of the hardware.txt file.
I don't ever think I had a Falcon by the time.

I don't think it is possible to disconnect completly the sound from the
crossbar, I'll have to check this with my Falcon.

If you look at the compendium, it gives another mapping for this
register (which seems to be wrong anyway).

I'll do some tests.


Teaser : based on this info (but not directly related), I should be able
to provide a fix to remove the noisy / random sound under Falcon
crossbar ;-)

By the way, could you test on a real Falcon a call to xbios $8c with
param=1 ?  (function sndstatus).

This is supposed to reset the sound to some default values and to
disconnect the crossbar matrix.

Can you read the crossbard registers af $ff89xx after this call, to see
what are those default values ?

eg :

move.w    #1,-(sp)
move.w    #$8c,-(sp)
trap      #14
addq.l    #4,sp


Just for the record, I had a look at the TOS part to handle trap $8c and $8b (Devconnect) and from there it seems not possible to completely disconnect the DAC output from the crossbar : the DAC will always be connected to 1 of 4 possible sources.

For those interested in $ff8930/$ff8932 registers, you can have a look at $e066d0 and $e06504 for those 2 xbios calls. Unfortunatelly, some of the undocumented bits are not used by those 2 calls, so it's hard to get an authoritative meaning for all the falcon's sound registers.


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