Floppy disks again

From: Bill Yakowenko <yakowenk_at_cs.unc.edu>
Date: Sun Oct 3 19:12:43 1999

Hey, with the discussion of diskettes recently, and my own
search for info on RX50's, I was a little surprised by the
lack of available info on single-sided single-density 5.25"
floppy disks (emphasis on SD). Were they ever actually
manufactured, or was SS/SD strictly an 8" thing? I seem to
remember seeing SS/SD 5.25" way back when. Can anybody
give me an authoritative rating of their coercivity? Were
they 300 Oerstedts, just like DD? If so, what is it that
made them single density? Something about the size of the
individual magnetic domains maybe? Or were exactly the same
diskettes called "double density" when we figured out how
to make drives to handle that?

Also, my web search lead me to conclude that a 360K DS/DD
floppy should probably work okay as an RX50; the only
difference seems to be the number of tracks per inch. But
they write many times more bits per inch along a track (maybe
over 3000bpi?) than they do tracks per inch (48 vs. 96), so
the media itself must have high enough resolution. Are the
magnetic domains long and narrow and aligned radially? Or is
there some other reason that it gets less resolution radially
(tracks per inch) than longitudinally (bits per inch along a
track)? If the precision of the drive is the only limiting
factor, then DS/DD should work perfectly fine as RX50s.

Clues are welcome.

        Cheers,
        Bill.
Received on Sun Oct 03 1999 - 19:12:43 BST