Re: [hatari-devel] DIP switch support

[Thomas Huth <th.huth@xxxxxx>]

Am Wed, 11 May 2016 15:40:31 +0000 (UTC)
schrieb Thorsten Otto <halgara@xxxxxxxx>:

> That looks strange to me for the TT case. Why is $9200 read as $3f
> when accessed as word, but $00 when accessed as as byte? The value
> for $9201 is the same in both cases. 

If the hardware engineers did not implement the bits here at all, the
byte value at $9200 is likely random, depending on the previous bus
traffic. We've seen this with a couple of other undefined bits in other
registers already, though it mainly happened for STs only, as far as I
remember, STE, TT and Falcon seemed to be more well-defined 'til now.

 Thomas

>     "Konador, Cyprian" <cyprian.konador@xxxxxxx> schrieb am 12:19
> Mittwoch, 11.Mai 2016: 
[...]
> DIP switches subject is Mega STe and TT only. 
> 
> 
> They are visible under the same address as STe Jaguar analog Joistick
> port.
> 
> Below you can find the outcome from my tests for my STe/ MSTe and TT:
>     move.w    $FFFF9200.w,Wartosc
> ; RESULT MSTE: FFF9
> ; RESULT STE:  FFFF
> ; RESULT TT:  3F03
> 
> 
>     move.b    $FFFF9200.w,Wartosc
> ; RESULT MSTE: Buss Error
> ; RESULT STE:  Buss Error
> ; RESULT TT:  00
> 
> 
>     move.b    $FFFF9201.w,Wartosc
> ; RESULT MSTE: F9
> ; RESULT STE:  FF
> ; RESULT TT:  03
> BR
> Cyprian
> 
> 
> 
> 
> 
> 
>