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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."

HD disks have a different media quality which requires a higher write
current signal in order to successfully write to the media.

Low density disks are cheap.  Go buy a box for $5.

-- 
#ifdef TRUE        | Fuzzy Fox (a.k.a. David DeSimone)       fuzzy@netcom.com
#define  TRUE   0  |
#define  FALSE  1  |  "You have been recruited by the Star League to defend
#endif             |     the Frontier against Xur and the Kodan Armada."

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!
>
>Jeric
>

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.

You can format the HD disks in the LD drive but you must either use virgin
disks (aka. never been formatted as HD) or completely erase the treacks
from the HD disk before formatting it in the LD drive.

You may get away with using a real strong magnet, a disk erasing utility
sush as bulkeras from copyiipc version 6 will definately do the trick.
I've trashed disks before that had the "Track 0 Bad, Disk Unusable."
when I tryed formatting them. Bulkeras fixed it up for reformatting again.
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evans1@cbnewsm.cb.att.com (Dan Evans) writes:
>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."

>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.

    There's an additional purely mechanical problem with using 5 1/4" HD 
disks in DD drives. DD 5 1/4" disks have a reinforcing "hub ring" that 
provides a thicker handle for DD drives to grab onto. HD disks do not 
have such a ring, so when you stick your HD disk in that DD drive there's 
a strong possibility that the disk won't be seated in the exact same 
alignment that it was when the data was originally written. Repeatedly 
removing and reinserting the disk will get you there eventually, but it's 
a bad idea as far as long term storage is concerned. If you're doing this 
to be able to exchange data with PCs that only have 360K drives then 
get yourself a bunch of real 360K floppies. You might even want to install 
a real 360K drive in a "media translation" machine so that you can write 
your 360K disks in a way that practically guarantees no hitches.

--
Nathan Engle                        Software Juggler
Psychology Department               Indiana University
nate@psygate.psych.indiana.edu      nengle@copper.ucs.indiana.edu

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 can format the HD disks in the LD drive but you must either use virgin
>disks (aka. never been formatted as HD) or completely erase the treacks
>from the HD disk before formatting it in the LD drive.
>
>You may get away with using a real strong magnet, a disk erasing utility
>sush as bulkeras from copyiipc version 6 will definately do the trick.
>I've trashed disks before that had the "Track 0 Bad, Disk Unusable."
>when I tryed formatting them. Bulkeras fixed it up for reformatting again.

Usually with 5.25" disks you will end up with problems.  3.5 disks you might
be able to get away with it.

Later,
-- 
John Villalovos
Certified Netware Engineer
villalj@xanth.cs.orst.edu
(503) 753-7883

Could the original poster be running afoul of one of the unformattable
format programs? I find these odious. To get the convenience of a dos 5.0
format without unformat files being written, I use Norton 4.51 safe format
using the "dos format" option. It readily formats hd 3-1/2's to ld. So will
dos 3.3 if you remember the options to use. I bet 5.0 works if you can
defeat the unformat provision.

-Ted Crum

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
------------------------------------------------------------------------------
Fred.McCall@dseg.ti.com - I don't speak for others and they don't speak for me.

In article <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:
>>>
>
>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.

I wasn't refering to the actual media coating on the disk. I was refering to 
the track width of the formatted tracks on the disk. There are areas on a
floppy that although are coated with the magnetic material, are not written
with data. 

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