Info on 3.5 floppy drives sought

[eckert@delos.informatik.uni-erlangen.de (Toerless Eckert)]

Hi

I have an apple2gs but never used it as a 2gs (okay, another story).
I don't have 3.5 drive so now i'm looking for one. First i wanted to
understand what different options i have, so here is just the questions
that garble in my mind. Hopefully somebody can fill me up with insight
into this matter:

- What different 3.5 drives will work on the apple2gs internal IWM controller ?
  (there's something like unidisk i've heard or the like) ..
- What's the capacity ? How does it read the data. Only thing i know is that
  old macintosh drives used to read with GCR and that they had different
  rotational speeds depending on the track. Do the 3.5 drives for the apple2gs
  exploit the same mean of access ?
- Are any of the drives sold for macintosh compatible with the
  internal controller on the apple2gs ? How about the correct adapter cable
  pinout ?
- what will i gain through a plug in disc controller card, i.e.: what
  kind of additional drives can i connect to one ? 
- How much for a apple2gs 3.5 drive by now ?

Alternatively please answer the following question
- Where's the FAQ that answers the above questions ?
---
             Toerless.Eckert@informatik.uni-erlangen.de
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