Re: [hatari-devel] Blitting from TT RAM seems to work on Falcon?

[Anders Eriksson <evldhs@xxxxxxxxxxxxxx>]

On Monday, October 9th, 2023 at 22:24, Nicolas Pomarède <npomarede@xxxxxxxxxxxx> wrote:


> Le 08/10/2023 à 20:25, Miro Kropáček a écrit :
> 
> > Hi,
> > 
> > I have a game which displays mayhem on CT60 (even with caches off) but
> > works perfectly fine in Hatari. After ruling out the usual suspects
> > (video base pointing to TT RAM, slow DSP, ...) the only thing which
> > remained is the Blitter which is used by the game.
> > 
> > Looking at the code it seems to be even explicitly allowed?
> > 
> > void Blitter_SourceAddr_WriteLong(void)
> > {
> > if ( Blitter_CheckAccess_Byte() )
> > return; /* Ignore access */
> > 
> > if ( ConfigureParams.System.bAddressSpace24 == true )
> > BlitterRegs.src_addr = IoMem_ReadLong(REG_SRC_ADDR) & 0x00FFFFFE; /*
> > Normal STF/STE /
> > else
> > BlitterRegs.src_addr = IoMem_ReadLong(REG_SRC_ADDR) & 0xFFFFFFFE; /
> > Falcon with extra TT RAM */ <---- Huh?
> > }
> 
> 
> Hi
> 
> i found a reference for this change in commit
> a02aedff2711b80379081abb82832c92aa0637f0 in dec 2014.
> 
> There were a lot of changes at this period regarding TT RAM and 32 bit
> addresses, but I really don't remember where this specific change came from.
> Didn't the afterburner of ct boards allow to blit from "TT RAM" too
> instead of just plain RAM ? Maybe the error comes from this and I mixed
> things with a normal falcon.



Hi,

no you can't use blitter from Afterburner or CT2 TT-RAM (as well as CT60/3)..

However there are some memory cards/accelerators where the "TT-RAM" lies within the lower 24-bit memory space. It's been quite some time but I think one is called Magnum and the other Falcon FX. I'm not sure if the blitter works though.

--
Anders Eriksson
ae@xxxxxx