> The 8-bit Atari 5.25" diskettes were FM encoded, so I doubt
> a PC diskette drive would make much sense of them.

The PC drives ought to be able read them.

FM =  Frequency modulation (single density)
      mid-cell transition = 1, no mid-cell transition = 0,
      transition at every cell boundary,
      magnetic domains of size 1 and 2.

MFM = Modified Frequence modulation (double density):
      mid-cell transition = 1, no mid-cell transition = 0,
      if there are 2 adjacent zeroes, a transition is added at the
      cell boundary,
      magnetic domains of size 1, 1.5 and 2

So they both need basically the same electonics and media quality!

The Shugart floogy interface (3.5 and 5.25 disks have the same physical
interface - so you can connect those old 5.25 drives from your beeb to
a modern PC) passes the 'raw' magnetic data.  I don't think support
for FM was ever removed from the FDC in PCs.

One possible problem is that the write head of moderm drives is a lot
narrower than on old drives (esp. the 40tpi ones).  So you may not
be able to write reliably.

	David