Apple ][e Memory Access Question

["Darkcode1" <no-one@microsoft.com>]

I have an enhanced apple ][e with 128k ram and after reading through some
old
nibble magazines of mine, i stumbled across this confusing bit of
information:

  It seems in the apple ][e, memory from $d000-$dfff has two banks where as
  memory from $e000-$ffff has only one, but what happens when there is a
memory
  card installed?  

I'm use to using the apple ][+ with language card...so, could somebody
please explain
all the memory bank switching and all the new I/O soft switches in the ][e.

--DarkCode1