DaveDDS wrote on 2025-08-13, 15:14:

I've been working on/mostly finished a little tool which might be of use: […]
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I've been working on/mostly finished a little tool which might be of use:

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1Floppy Disk Recover
2
3use:    FDR <drive>: file[.FDR] [options]
4
5opts:   -L      Low density
6        -N      New
7        -M      force Monochrome
8        -?F     show Format of .FDR
9        -?I      ""  Interactive keys
10        -R      Review .FDR (no updaate))           FDR file.FDR
11        -I      Convert .FDR to raw .IMG              ""    ""   outfile
12
13FDR can help recover diskette sectors which fail "normal" reads, but may be
14read with minor drive alignment adjustments or other treaks.
15
16It will auto-read the entire disk, show the read-status of the tracks/sectors,
17then let you manually seek, select and try reading individual       ""      as
18you "tweak" the drive.

Regretable I'm travelling at the moment, and won't be able to properly update
my site for about a week - if you need it sooner, we could find a way to get
it to you.

This sounds interesting but there's no rush, whenever you can it's fine. Cheers!

Ok, I have placed in in a "temporary drop" area of my site, you should be
able to get it from my site at:

1   https://dunfield.themindfactory.com/Drop/FDR.ZIP

Be sure to read the enclosed FDR.TXT

DaveDDS wrote on 2025-08-15, 15:12:

Ok, I have placed in in a "temporary drop" area of my site, you should be able to get it from my site at: […]
Show full quote

Ok, I have placed in in a "temporary drop" area of my site, you should be
able to get it from my site at:

Copy code to clipboard

1   https://dunfield.themindfactory.com/Drop/FDR.ZIP

Be sure to read the enclosed FDR.TXT

Hi, Thanks for sending this! I will try it later today.

DaveDDS wrote on 2025-08-13, 17:46:

If you want to recover ANY of the original data on the diskette, DON'T go near it with a magnet!

You don't understand, the data on this diskette is not unique, it is free to download from the internet, there is no point in trying to restore content.

100% copy of what Decrypt have on this Doom diskette floppy is available online as floppy image. So he can alway overwrite image to floppy, making it back authenticity.

And recording the image will be better and more reliable than any recovery.

It would be a different matter if it were a unique floppy disk that did not have backups anywhere.

MAZter wrote on 2025-08-19, 12:38:

You don't understand, the data on this diskette is not unique, it is free ...
It would be a different matter if it were a unique floppy disk that did not have backups anywhere.

You're right - I don't understand - if the data is free and you just want to restore the diskette to "readable", then
it's trivial - just bulk erase the diskette, then format and write on the replacement data.

If the diskette is physically damaged and can't be formatted, and you want to recover the original for "posterity",
then you're mostly OOL - I have restored distribution diskettes which were physically damaged by opening
them and replacing the media "disc" with one from a new/umdamaged diskette - but doing so with non-obvious
results can be very difficult.

Unless you want the actual original diskette in working condition, it's much simpler to just write the data onto
a new diskette - if you really want to be able to "show" the original as a historically significant bit of software,
you are unlikely to want to be reading it (putting further wear on it) - so does it really mater if it's not readable?

DaveDDS wrote on 2025-08-19, 13:45:

then it's trivial - just bulk erase the diskette, then format and write on the replacement data.

I just wanted to write that in some cases formatting is not enough, and after touching with a magnet formatting goes without errors.

MAZter wrote on 2025-08-19, 17:27:

DaveDDS wrote on 2025-08-19, 13:45:

then it's trivial - just bulk erase the diskette, then format and write on the replacement data.

I just wanted to write that in some cases formatting is not enough, and after touching with a magnet formatting goes without errors.

go all scorched earth on that floppy which is what i had to do with hdds intentionally wipe them then screw it up so the software sees nothing on it and therefore can fully format it. I call it computer hiccups or tainted drive where theres files from before like a virus smeared itself on the drive and the only way to wipe it is physically magnet next to platters. I take old hdds and use the magnets for these purposes, small enough to hit the area but not too big or strong that i fry the electronics

MAZter wrote on 2025-08-19, 17:27:

I just wanted to write that in some cases formatting is not enough, and after touching with a magnet formatting goes without errors.

I thought we had been through this in this thread already .. if you can't format/write a disk without "magnet" erasing it first. then you
have a drive problem ... most likely alignment which can leave "bits" for former tracks ... this won't affect the ability to read it on the
(misaligned drive it was written on as the head will align with the fresh track - but can cause problems on other (better aligned) drives
as they might see both conflicting signale ...

Note that the drive(s) have to be badly misaligned for this to be a real issue, with a slightly misaligned drive, the new track will be so much
stronger that any remaining edge of an old track that the data seperator will lock on to it.

A related thing - if you write a 40 track image (5.25" 360k) over another 40-track image,
using a double-stepped 80 track drive (5.25" 1.2m) - the tracks are thinner. This means that even on properly
aligned drives, the edges of the original 40-track image will still be at the edges of the 40-on-80 image.

Again, this won't cause problems reading back on the 80-track drive (which only sees the width of the new
image), but can cause problems when reading on a 40-track drive as the edges of the first written track will
be stronger. (I don't think DOOM ever shipped on 5.25" media = so this wouldn't be a problem in this case)

Best practice, use known well aligned drives (ImageDisk has a tool to help adjust alignment), and bulk-erase any
disks if you want to insure that no vestiges of the original data remain - especially important it writing 40-tracks
on 80 track drives.

Recommend using a proper bulk eraser instead of a magnet - the magnet will write domains that it comes close to,
and not ones further aware from it - you would have to spend a lot of time moving the magnet carefully over the entire
media surface to get even close to a bulk-eraser - even so, the domains will be written in consistent directions and
NOT randomized. Bad guys with very specialzed equipment might still be able to recover the original data (as magnetic
strength is additive).

A bulk eraser on the other hand is an alternating magnetic field (basically an electromagnet on AC) - once activated,
you press it againt the disk, then move it well away before deactivating it - this causes the domain flipping to be reduce
to near nothing more slowly - this will randomize the domains much better than a perment magnet.

If you don't have a bulk eraser, you can make one by powering an electromagnet via an AC transformer,
you can get electromagnets from all kings of things: Mechanical doorbells, relays, a coil of wire wrapped around a nail.
Of course make sure the coil is long enough and the power it draws are with the realm of the transformer you
are using.