HD Floppies in DD Drives

From: Grant Zozman <gzozman_at_escape.ca>
Date: Sun Nov 9 08:43:15 1997

Here's a silly question, but one I've never understood:

Why can't a high density 5 1/4" disk be formatted in a double density
drive? When I try, DOS returns a "Track 0 Bad" error message.

I thought that a HD disk would simply have a denser coating of magnetic
material applied evenly over the entire surface of the disk. I don't
see why this should cause problems for a DD drive. However, a few
questions come to mind. Is the magnetic coating of a different
sensitivity, resulting in a weaker signal for the heads to pick up? Is
the magnetic coating applied to the media in "tracks", causing problems
when a different TPI spec is attempted on the disk?

Since some of the software for my "old" (first generation PC) computers
is on 5 1/4" disks of dubious condition, I would like to make copies
onto new disks. Since HD disks are still readily available and cheap, I
thought this would be an ideal way to do so.

I also seem to have fried the 5 1/4" HD drive in my PC while sorting
through some old software. It seems a couple of disks had some dirt on
them which caused horrible screeching sounds when the disk was spinning,
and also deposited a very hard black coating on the heads. The only way
I could remove the deposits was to scratch it off with my fingernails
(alcohol would not touch it). However, I must have bumped the heads out
of alignment, because the drive won't read disks any longer.

My question is: can I plug a Double Density drive into the same
connector in my modern PC and use it for my old disks? I know I will
have to change my BIOS setting, but is there anything else I need to

Any input on the above would be much appreciated... thanks in advance!
Hope this isn't too far off topic.

Grant Zozman
Received on Sun Nov 09 1997 - 08:43:15 GMT

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