[hatari-devel] some falcon registers questions

Laurent Sallafranque laurent.sallafranque at free.fr
Tue Feb 1 21:59:31 CET 2011


Hi,

I'm asking myself questions about some Falcon registers.


$FFFF8006: Monitor Type BIT 7 6  (These 2 bits are duplicated in 
$FFFF82C0 (BIT 1 0))
   00 - Monochrome (SM124)
   01 - Color (SC1224)
   10 - VGA Color
   11 - Television

$FFFF8006: Memory configuration BIT 5 4
   00 -  1Mb
   01 -  4Mb
   10 - 14Mb
   11 - no boot !

Is this true ?

$FFFF8006 is read only, the 2 monitor bits seems to be copied into 
$ffff82c0.
But $ffff82c2 is read / write. So what happen to these 2 bits if I 
change their value while writing something to $FFFF82C2 ?
Do they are "sticked" to their "$FFFF8006" value ?
Do they are refreshed ? (when ?)
Do they keep the value I give to them in $FFFF82C2 ?



$FFFF8007 Falcon Bus Control
     BIT 6 : F30 Start (0=Cold, 1=Warm)
     BIT 5 : STe Bus Emulation (0=on)
     BIT 3 : Blitter Flag (0=on, 1=off)
     BIT 2 : Blitter (0=8mhz, 1=16mhz)
     BIT 0 : 68030 (0=8mhz, 1=16mhz)

Is this correct ?
I've seen some hardware files when 0=on and some other where 0=off



$FFFF8201/03/0d : Video Base Hi/Mi/Lo

On Ste, when one writes to Hi or Mi register, low register is reset.
Is it still true for the Falcon ?



$FFFF8264.B|RW|VDL_HSH|H-Scroll Hi                          %____xxxx |F
$FFFF8265.B|RW|VDL_HSL|H-Scroll Lo - clears Line Wide       %____xxxx |STE,F

Some docs indicates that $FFFF8264 exists for the Falcon.
Some other don't.
Where is the truth ?



For the sound now : $FFFF8920
I've read in a doc that STE values in the Falcon don't use the same 
frequencies as STE value in the STE ?
All docs say that Falcon STE sound is nute, 12517 Hz, 25033 Hz, 50066 Hz
But one doc says that Falcon STE sound is nute, 12292 Hz, 19668 Hz, 49170 Hz

Is this true ?

            |  |       | Falcon:nute------STE: 6258 Hz--------------00 
|F,STE
            |  |       | Falcon:12292 Hz--STE:12517 Hz--------------01 
|F,STE
            |  |       | Falcon:19668 Hz--STE:25033 Hz--------------10 
|F,STE
            |  |       | Falcon:49170 Hz--STE:50066 Hz--------------11 
|F,STE





$FFFF8802.B|rW|PSG_DAT|Write Data                                     |
            |  |       | PSG Register 14 - Port A            %RICDPBAS |
            |  |       | Reset IDE 0:no,1:reset (slow down)---+||||||| |F
            |  |       | Internal Speaker 0:on,1:off-----------+|||||| |F
            |  |       | Centronics Strobe----------------------+||||| |
            |  |       | Reset DSP 0:no,1:reset------------------+|||| |F
            |  |       | Printer Select In------------------------+||| |
            |  |       | Drive B select 0:on,1:off-----------------+|| |
            |  |       | Drive A select 0:on,1:off------------------+| |
            |  |       | Side select 0:side1,1:side0-----------------+ |
            |  |       | PSG Register 15 - Port B            %xxxxxxxx |
            |  |       | Centronics Data Port-----------------++++++++ |


What kind of DSP reset is done here ?
Is it a cold reset or a warm reset ?


Stop for now.
It makes enough questions.

Thanks in advance.

Regards

Laurent




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