[hatari-devel] some falcon registers questions

Laurent Sallafranque laurent.sallafranque at free.fr
Tue Feb 1 22:57:47 CET 2011


Many thanks for your help.

 > I didn't try but I'd say so :) I think those bits come from hardware, 
i.e. it's really no way to change them.
 > If you insist, I can try it.

And plizz ;) Would you ?

Regards

Laurent


Le 01/02/2011 22:47, Miro Kropác(ek a écrit :
> Hi,
>
>     $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
>
> True.
>
>     $FFFF8006: Memory configuration BIT 5 4
>      00 -  1Mb
>      01 -  4Mb
>      10 - 14Mb
>      11 - no boot !
>
> 11 is also mentioned as reserved, in all cases, not used.
>
>     $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 ?
>
> I didn't try but I'd say so :) I think those bits come from hardware, 
> i.e. it's really no way to change them. If you insist, I can try it.
>
>     $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 ?
>
> Yes.
>
>     $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 ?
>
> Yes.
>
>     $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 ?
>
> It does exist but not as shadow register but more like hi-byte (which 
> is unused). I.e. it's legal to write *(unsigned short*)0xffff8264 = 
> [0-15] as well as  *(unsigned char*)0xffff8265 = [0-15] ... however, 
> writing to 8264 alone does something but I'm unable to tell you what. 
> It scrolls the screen but the picture is gambled.
>
>
>     All docs say that Falcon STE sound is nute, 12517 Hz, 25033 Hz,
>     50066 Hz
>
> This is correct.
>
>     But one doc says that Falcon STE sound is nute, 12292 Hz, 19668
>     Hz, 49170 Hz
>
> Bullshit, those values come from Falcon sound system, not from STE 
> compatibility mode.
>
>     What kind of DSP reset is done here ?
>     Is it a cold reset or a warm reset ?
>
> Coldest reset ever ;) It switch off DSP in hardware. Look into 
> NoCrew's DSP bootstrapper, there's is nice usage of this functionality.
>
> -- 
> MiKRO / Mystic Bytes
> http://mikro.atari.org
>
>
> _______________________________________________
> hatari-devel mailing list
> hatari-devel at lists.berlios.de
> https://lists.berlios.de/mailman/listinfo/hatari-devel

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