🚀 go-pugleaf

In <1hb8h7INN4t6@flop.ENGR.ORST.EDU> villalj@xanth.CS.ORST.EDU (John Villalovos) writes:

>In article <1992Dec23.202219.114@cbnewsm.cb.att.com> evans1@cbnewsm.cb.att.com (Dan Evans) writes:
>>In article <jeric.67@berkp.uadv.uci.edu> jeric@berkp.uadv.uci.edu (Jeric Woo) writes:
>>>I have some high density 3.5" and 5.25" diskettes that I would like to
>>>use as low density diskettes.  However, whenever I attempt to format them
>>>(using low density drives) I get either the messages "Bad or Invalid Media"
>>>or the message "Track 0 Bad, Disk Unusable."
>>>
>>>Why can't I do so?  Are the any other physical differences between high 
>>>density diskettes and low density diskettes (I know that 3.5" HD has a hole
>>>at the upper left hand corner, and that maybe HD disks has higher "surface
>>>density").  I even ran the diskettes through a magnet before formatting
>>>them, but still no luck.  Thanks!
>>>

>Yes there are physical differences in the media.  The differences are more
>apparent on 5.25" diskettes then on 3.5".

>>The LD drive heads are larger then the HD heads.  As a result the LD heads
>>are reading more then one track at a time on the HD disk. Track 0 isn't
>>bad, it's just smaller then the LD drive is capible of reading it.

>I don't believe that is correct.  If you look at a floppy disk they aren't
>composed of tracks of magnetic media.  The media is a continuous (sp?)
>coating on the disk.

You are correct; the preceding statement appears to be a
misunderstanding related to how the DRIVES write to the disks.  The HD
disks have a much higher coersivity(?) -- that is, they require a much
strong magnetic field to 'write' to the disk, and they hold less of a
field.  This is how narrower tracks can be written without
'bleedover'.  The weaker write field of the DD drive simply can't
write to the HD disk.  This is the case for 5.25" diskettes.

I always thought that the 3.5" diskettes were using the same media, so
I'm not sure why those would give a problem.

-- 
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
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