Re: [hatari-devel] HDDriver issues with WinUAE CPU core (and with EmuTOS) -> RAM detection issue

["Roger Burrows" <rfburrows@xxxxxxxxx>]

On 11 Jan 2015 at 1:58, Eero Tamminen wrote:

> 
> VDI screen memory needs to reside in Atari RAM so that
> it can be written.  If it's larger than normal ST screen,
> space must be done for it.  stMemory.c:
> -----------
>         /* Set memory size, adjust for extra VDI screens if needed.
>          * Note: TOS seems to set phys_top-0x8000 as the screen base
>          * address - so we have to move phys_top down in VDI resolution
>          * mode, although there is more "physical" ST RAM available. */
>         screensize = VDIWidth * VDIHeight / 8 * VDIPlanes;
>         /* Use 32 kiB in normal screen mode or when the screen size is 
> smaller than 32 kiB */
>         if (!bUseVDIRes || screensize < 0x8000)
>                 screensize = 0x8000;
>         /* mem top - upper end of user memory (right before the screen 
> memory).
>          * Note: memtop / phystop must be dividable by 512, or TOS crashes 
> */
>         memtop = (STRamEnd - screensize) & 0xfffffe00;
>         STMemory_WriteLong(0x436, memtop);
>         /* phys top - This must be memtop + 0x8000 to make TOS happy */
>         STMemory_WriteLong(0x42e, memtop+0x8000);
> -----------
> 
This is pretty bogus for a TT or a Falcon ... and I believe this issue was 
related to running TOS 3.06, so must have been TT emulation ...

Roger