3-1/2" Floppy Market Cornered

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Wed May 21 18:59:00 2003

On Wed, 21 May 2003, Tony Duell wrote:
> > My atari ST, Amiga 500,1200 Use them. DD disk drives were only used for a
> > few years so everybody went to HD production (still in use).
> 2 points :
> 1) The HP 9114 drive that I mentioned used _original_ DD drives, rotating
> at 600rpm. When these drives were designed, the HD disk hadn't been
> thought of...
> 2) Even now, HD drives have a switch to detect the hole in the HD disk,
> and one thing this switch does is to change the head write current to
> cater for the different coercivity of the DD and HD media.
>
> Have you got _proof_ (either from schematics, or by actually measuring
> the write current in an opertation drive) that the write current is the
> same for both DD and HD disks in a correctly-functioning name-brand
> drive? Becasue I am darn sure it isn't!

No, but "DD" drives initially, for obvious reasons, did not have a switch.
Many people who were oblivious to differences in reliability used HD
diskettes in DD machines, and thought that they worked correctly.
I think that THAT is what he meant by "everybody went to HD" in reference
to his Atari, Amiga, etc. experiences.

And, I can easily show you "HD" drives that do not have a switch! IBM did
not put a switch in their original "1.44" drives in PS/2's. Some users of
those claim that DD diskettes work correctly. (and then later complain
about the COMPUTER being "unreliable")

At no point has the price differential been so extreme as to justify using
the wrong diskette on a regular basis. Admittedly, there can be
"emergencies", where the correct diskette is unavailable that might result
in a need to make do with a wrong one.
Received on Wed May 21 2003 - 18:59:00 BST