360K in a 1.2M drive (was: Parallel port hard drives?

From: Richard Erlacher <edick_at_idcomm.com>
Date: Wed Mar 29 07:48:12 2000

I think we're homing in on the target topic now . . .

Please see embedded comments below.

Dick

----- Original Message -----
From: Fred Cisin (XenoSoft) <cisin_at_xenosoft.com>
To: <classiccmp_at_classiccmp.org>
Sent: Monday, March 27, 2000 11:02 AM
Subject: Re: 360K in a 1.2M drive (was: Parallel port hard drives?


> On Sun, 26 Mar 2000, Richard Erlacher wrote:
> > I'm in agreement, pretty much with what's been said here. Please see
> > embedded comments below.
> > Yes, but, given that the goal is to write a 48TPI 360K diskette, the
> > coercivity will be the same, since the media are the same. It's worth
>
> Are you saying that a 300 Oerstedt diskette is the SAME as a 600 Oerstedt
> diskette?? Is TRI-X camera film the same as Pan-X, also?
>
No, I'm not. I'm saying that the original problem, (assuming that i ever
grapsped it in the first place) was to write a 48TPI diskette. That means
that the 96TPI diskettes are not part of either the problem or the solution.
What's under study is the effect of writing a 48TPI diskette in a drive
intended for 96TPI use. Since there are no 600 or 720 Oerstedt diskettes
that are part of this problem, they need not be considered.

Nevertheless, it's probably helpful to understand WHY the different drives
and the media that go in them are important, in fact, definitive, to the
discussion.
>
> > target medium is the 300-Oerstedt 48TPI 5.25" diskette. The issue was
that
> > the old 48TPI disk drive had trouble reading the 48TPI diskette written
on a
> > 1.2MB 96TPI drive. The reason is not the media, it's the drive. Why?
> > It's because the medium is the same physical diskette. It cancels out
of
> > the equation.
>
> The symptoms described (inability to read a diskette written in a 1.2M
> drive, supposedly as a 360K) match TWO possibilities:
> 1) failure to bulk-erase and format in the 1.2M, when the diskette had
> residual 1/3mm wide tracks.
> 2) use of a 600 Oerstedt diskette when trying to create a 360K.
>
> Either (OR BOTH!) of those mistakes would give the symptoms described.
>
> I fail to see how the media could be "cancels out of the equation". The
> magnetic coercivity of the diskette would not magically be altered into
> the correct one by any action of the drive. Setting the ASA dial on the
> camera to 400 does NOT convert Pan-X film into TRI-X.
>
It cancels out because one wishes to write 48TPI on 48TPI-specified- media
but do so in a 96TPI HD drive.
>
> > There are folks who enjoy claiming that their risky way of doing things
is
> > better than paying the 10% extra for the correct product.
>
> Agreed
>
>
> > Let's try to keep the 3.5" diskettes out of the picture for now. The
720K
>
> Mentioned simply because:
> the gap in coercivity of the different 5.25" diskettes is SIGNIFICANT.
> The gap in coercivity of the different 3.5" diskettes is much less.
> Therefore any success in using wrong diskettes in 3.5" should not be
> extrapolated to apply to 5.25"
>
I just wanted to keep them out of the discussion, since there are "720K"
diskettes in the 5-1/4" IBM-world with which they could be confused. I
don't believe that they actually format to a 720K capacity in applications
outside the "IBM"-PC world. They would, I guess, if one formatted them with
9 sectors of 512 bytes per track.
>
> > Some of the controllers switched the data rate and in other cases the
drive
> > switched speed.
>
> Because it is on topic for collectors: The original IBM AT switched data
> transfer rate. Many later went for dual spindle speed. Both methods
> seemed to work OK. The Weltec 250Kbps/180RPM 1.2M was trying to stretch
> things a little too far.
>
> --
> Grumpy Ol' Fred cisin_at_xenosoft.com
>
>
Received on Wed Mar 29 2000 - 07:48:12 BST