Need help with retrieving data from a DOS 2.11 formated

From: Jerome Fine <jhfine_at_idirect.com>
Date: Tue May 8 15:52:28 2001

>Tony Duell wrote:

> > [BTW, on the Computer Bowl, nither billg nor anyone else on his team knew
> > where the write protect notch is on an 8" diskette!]
> Did they know that it's 'inverted' wrt the 5.25" notch -- that is to say
> on an 8" disk you cover the notch to enable writing to the disk. That
> makes a lot more sense IMHO -- if the tab falls off, the disk is left in
> a 'safe' state (write-protected).

Jerome Fine replies:

When I used the DEC RX02 compatible drives, we sometimes had
to look around for that tab so we could write on the media. A bit
inconvenient, but as you say, a good fail-safe design.

What was even more annoying was the different location of the sensor
holes for a double sided (RX02 => RX03) floppy. Eventually, I just
added a reversing (DPDT) switch on the sensors of a DSD 880/30
so I could use a SSDD 8" floppy as DSDD.

> Onm the other hand, with the 5.25" disk you can have a permanently
> write-protected disk (no notch at all), as was used for some software
> distribution kits. You can't do that with the 8" disk -- it's always
> possible to stick something over the notch.

Not necessarily true. At one point, I rigged an RX50 drive to think that the
"notch" was still there and was then able to write on the media. Of course,
I still had to format the media since originally it was not RX50 compatible.
At one point, I used an Emulex DM01 with a floppy drive that had a
light sensor to detect the "notch". So for the moment, I unbolted the
sensor and used a flashlight to simulate the "notch" being there.

So don't assume that those "permanently write-protected" floppies can't
have other information written on them - a bit inconvenient, but not
that much of a problem.

Sincerely yours,

Jerome Fine
Received on Tue May 08 2001 - 15:52:28 BST