Re: Apple IIc plus

["mressl@gmail.com" <mressl@gmail.com>]

Hello again!

The IIc plus's MIG (Magic Interface Glue) device seems to be still a
mistery, but I have found out the following:

* The memory range is indeed $CE00-$CEFF (only when ROM Bank 2 is
activated)
* The memory seems to be bank-swapped, with banks of 32 bytes (yes,
only 32 bytes)
* There seem to be 64 banks, thus the total amount of memory is 2 kiB.
This also matches Apple's documentation
* A bank is accessible at $CE00-$CE1F
* It seems that $CEA0 resets the current bank to 0
* It also seems that every access to $CE20 increments the current bank
* There are accesses to $CE40 and $CE60 that so far I have no clue as
to what they do
* It seems the MIG memory is used as a sector buffer, not as a track
buffer. This makes sense, as a 3.5" GCR disk sector is about 700 bytes

Anybody else interested in resolving the mystery? :-)

Marc.-