Re: Is it a hard or soft sectored disk?

From: Michael Huth (
Date: 2005-11-02 02:14:30

Hash: SHA1 wrote:

| On 2005-11-01, at 23:33, Anders Carlsson wrote:
|> I always thought disks once formatted on a PC were forever
|> useless on other (C64/Amiga) systems, even if the disk was of the
|> right capacity. I don't know why, but I experienced R/W errors in
|> particular on 3.5" DD disks once used on a PC but later
|> reformatted on Amiga.
| I never noticed that and - at some point - I passed hundreds of DD
|  diskettes through my workshop, which all were originally msdos
| formatted.
Hmm, the magnetic properties of the disk surface should be different
for HD and DD. HD drives usually use a higher current (i.e. field) to
magnetize the surface.
So DD disks can be formatted to HD if the surface is good enough. As
far as I remember this was often used with 3.5" disks and an
additional hole.
Ok but if you take a HD in a DD drive it will change the direction of
magnetisation not completely.
f.e. if you take a HD written and the DD drive has to change the
magnetisation it will change maybe 70%. Or maybe just the upper layers
of the surface.
At least it seems that the magnetisation does not stay for a long time.

This might also be true if you use a DD disk in a HD drive, but not as
If you put the disk in a strong and slowly decreasing alternating
magnetic field the magnetisation will probably removed. (about 1 kHz
should be ok)

Well but this doesn't help the question 8)
So is there maybe some visible difference in the properties of the
disk? (dark / light brown or maybe the thickness visible against a light?)

I also heard rumors that the surface for HD and DD is the same. But
this would mean that the disk once used in a HD drive is no more
useable in a DD drive?!?


Version: GnuPG v1.2.2 (MingW32)
Comment: Using GnuPG with Thunderbird -

       Message was sent through the cbm-hackers mailing list

Archive generated by hypermail pre-2.1.8.