Date   : Wed, 09 May 1990 17:44:45 GMT
From   : usc!zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink!a577@ucsd.edu (Curt Sampson)
Subject: floppy drive hardware

> Besides, always be aware that the capacities of 720K and 1.44M (as well as
> 360K) do NOT use all legal resources of disk and drive.  It's just that IBM
> (who else) wasted about 10 / 18 percent of possible capacity FOR NO REASON!

Well, I can't comment on the higher density drives, but I've heard that IBM did
have a good reason for using 360K DSDD 5.25" diskettes rather than 400K.
Apparently the Intel disk controller that IBM used in their original machine is
not reliable writing and reading 10 sectors per track.  So the started out with
8, and then moved up to 9.  My Kaypro 4, using the Western Digital controller,
reads/writes 10 sectors/track (400 K/disk) with no problems.  There's even
someone out there doing 11 sectors/track (440 K/disk) successfully.
  I guess it was a little dumb of IBM to go with the Intel rather than the WD
controller, but then again, what did you expect after they chose the 8088....
:-)
          -cjs     ( Curt_Sampson@mindlink.UUCP )