Msg: 3638 *Conference*

12-24-92 17:18:51

From: FRANK PERRICONE

To : RICHARD HANSON

Subj: HD DISKS

In order for a HD disk to hold so much more info without each bit of info
exerting a magnetic force that could scramble the bits next to it, they have to
make them a lot more resistant to magnetic forces, which means the read/write
heads have to be able to put a lor more magnetic energy into it.  This is
measured in something called oersteds (I could be mispelling it).  Formatting
an HD 3.5" disk as lower density sometimes works, but even when it does, the
signals tend to degrade over time because they weren't pushed hard enough into
the medium, so to speak, so they're not reliable.  The old 5.25" disks we all
used to use long ago didn't hve this problem because they made them
high-density in a different way, althogh the disk manufacturers wanted us to
believe they did so we'd buy more expensive disks than were necessary (remember
the old disk-notching days?), but with 3.5" disks, it really is necessary.