Re: [hatari-devel] add support for TT ram -> problem with HD emulation and DTA

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 17/12/2014 17:29, Roger Burrows a écrit :

> On a TT, to the best of my knowledge, no data is transferred if you try to DMA
> to/from TT RAM.  There is no TT RAM on any other original Atari system, but I
> believe that the same is true for the CT63.  I can easily write a program to
> verify if you wish (I have the hardware).

I thought I read the TT had a 32 bit DMA for the ACSI part, but FDC and 
audio used 2 24 bits DMA ? But maybe I'm mixing with sthg else.

But it could be interesting to see on a TT the different cases of 
reading with the FDC and the HDC to $01080000 for example (depending on 
the expansion RAM you have) and see if at the end of the transfer the 
data are at $80000 (after masking to 24 bits) or $01080000.

By the way, if you have a TT, have you ever tested if all the memory 
between 0x01000000 and 0xFEFFFFFF return a bus error, or is it just 
between 0x01000000 and 0x7FFFFFFF ? As this is how TOS/EmuTOS check for 
extra RAM, I wonder what would be the physical limit.

Nicolas