[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Recode to Play MP3?



georg.bieling@gmail.com wrote:
On May 23, 11:21 am, "Michael J. Mahon" <mjma...@aol.com> wrote:

Actually, it cannot safely cache "sub-bank-switched" regions of memory
without "knowing" their bank-switch protocols, and, unfortunately, the
$C800-$CFFE region is such a sub-bank-switched region.  If it could be
made slot-specific, and the cache logic took the slot that originated
the /IOSTROBE into account, it could work, by disabling caching of the
extension space when switched in by certain slots.  I don't know of any
accelerators that go to this length.



Even then, a Videx Videoterm for example would not work, because tha
video RAM is bank-switched in 512 byte chunks into this c800.cfff
area.

Using the approach I suggested, this would work if the slot were
marked "slow"--meaning never cache its slot ROM area or the expansion
ROM space if enabled by this slot.

*Any* card-specific bank-switching, RAM or ROM, would have to disable
caching, since the accelerator would have no way of knowing how the
banks were switched.

-michael

NadaNet file server for Apple II computers!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
tool--and it's seriously underused."