[hatari-devel] some videl emulation news

[Laurent Sallafranque]

 > are you sure of this?

No, it's only a guess.

I've guessed it from 2 things I read :

- the ST Shifter fills it's internal buffer at end of HBL. I think this 
could be the same behaviour for the Videl.
- I'm pretty sure I've read it somewhere, but I can't find where.

Anyway, only good benchs would confirm that.


Regards

Laurent


Le 05/06/2011 23:49, Anders Eriksson a écrit :
> On Sun, 5 Jun 2011, Laurent Sallafranque wrote:
>
>>  - Sometimes, the same line is copied twice, which means that the 
>> videl's got an internal memory, but how much ?
>>  - When and how is it filled ?
>
> Hi,
>
> are you sure of this?
>
> I'm having flashbacks from a long time ago when we did a lot of 
> video-DMA tests and that a 320x200 and 320x100 (same mode but with 
> double line enabled) left equal amount of bus for the CPU. That 
> indicates that the videl just read the data twice from memory. Then 
> the doubling is simply an address counter that updates every second 
> scanline instead of each.
>
> But as my memory is what it is (very poor) I guess one would need to 
> benchmark this again to be sure :)
>
>
> -- 
> Anders Eriksson
> ae at dhs.nu     http://www.dhs.nu/
> ae at atari.org  http://www.atari.org/
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