|Re: [hatari-devel] test needed on a 4MB STF|
[ Thread Index |
| More lists.tuxfamily.org/hatari-devel Archives
Nicolas Pomarède schrieb:
> I agree, not really needed for emulation too, but it's true that when
> you nearly have a description of the inner working of this part of the
> MMU, it would be nice to understand the reason and duplicate even the
> strangest effect :)
I think I have now reverse-engineered how the access signals for the RAM
banks are generated for the Ricoh (aka non-IMP) MMU. Phey, I fear I'm
going to dream of logic gates and Boolean algebra tonight...
I can indeed see the "hole" for the bank0=128k, bank1=2M configuration.
No RAM access signals are generated for this configuration and A21..A18
= 0001, which is exactly the address range from $40000 to $7ffff. I'll
see if I can find some time during the holidays to transfer my
hand-written notes into some kind of documentation of my findings.
Christian Zietz - CHZ-Soft - czietz@xxxxxxx
PGP/GnuPG-Key-ID: 0x52CB97F66DA025CA / 0x6DA025CA