RE: Can Linux read DMF format floppies?

Manfred Bartz (
Wed, 21 Aug 96 07:24:52 UT

> From: on behalf of Ron Holt
> Sent: Tuesday, August 20, 1996 4:10 PM
> To:
> Subject: Can Linux read DMF format floppies?
> Can Linux read DMF format floppies? DMF is Microsoft's "Distribution Media
> Format". Some of the applications they make are distributed in this floppy
> format. I don't know the exact geometry of these floppies. I've been
> told it's something like 21 instead of 18 sectors per track. Does anyone
> know where I can find a spec for DMF?
> Thanks,
> Ron
> PS. Yes, I've looked at floppy.c in the kernel source...
> --
> Ron Holt <> Caldera, Inc.

DMF is essentially a special format that fits more data on the diskette by
reducing the gap between the sectors. Because of this, the disk must be
written a whole track at the time.
I am fairly sure that I saw a utility in the Win-NT forum on Compuserve that
writes a DMF image to the diskette - presumably after you have assembled the
image into one great big file.

Manfred Bartz <>

Windows is so simple - it obviously is the OS of choice
for hairdressers, taxi drivers, labourers...

BEGIN Extract from the 'Microsoft Solutions Development Kit 2.0':

Warning Because DMF has been only recently developed, many existing disk
examination or copying utilities do not recognize DMF and can corrupt the DMF
disk. For more information, see -DMF Disk Issues- later in this section.

What Is DMF?
Microsoft Office 3.5" floppy disks are created using a recently developed
compression and disk creation technology that reduces the number of floppy
disks needed to install Office. The three parts to the new technology are
Diamond, Quantum, and DMF.

A disc layout tool used by Setup that combines multiple files into a single
cabinet (CAB file) or across multiple cabinets on separate disks. Extract.exe
is the tool used for extracting and decompressing a single file from a Diamond
cabinet, or for copying Diamond disk images from floppies to the network; it
cannot put new or changed files back into a cabinet. Extract.exe is described
later in this section.

New compression algorithm used by Diamond.

Distribution Media Format is essentially a method of storing 1.68 MB of data
on a high density 3.5" floppy disk. Because DMF reduces the gap between
sectors, there is no way to write to a DMF floppy disk using standard disk
copying tools without damaging the floppy disk.
Disk 1 of a DMF disk set is always a normal, 1.44 MB read/write disk so it can
be handled using normal disk utilities such as the MS-DOS COPY command.
To create or copy a DMF disk, the DiskWrite utility is used. For Select
customers, DiskWrite is available on the Select CD. For MOLP customers and
corporate accounts with disk duplication rights, DiskWrite is available on a
fulfillment CD from Microsoft. All other customers can obtain additional DMF
disks by calling Microsoft at 1-800-360-7561, or non-DMF equivalent disks can
be obtained through Microsoft Customer Service.
DMF has no effect on Setup functionality and is used only for storing software
on when put on floppy media.

DMF Disk Issues
Because of the way DMF modifies the disk at the sub-sector level, a DMF disk
cannot be handled in the same way as a standard MS-DOS disk. Here are some of
the issues to keep in mind:
Many existing utilities such as Norton Disk Doctor, Microsoft ScanDisk,
MS-DOS DiskCopy, and Microsoft Windows Copy Disk do not recognize DMF.
You should not use disk utilities to examine a DMF formatted disk, as
these utilities can corrupt the DMF disk.
You cannot copy DMF formatted disks using MS-DOS DiskCopy or Microsoft
Windows Copy Disk. You must use the tool Extract.exe.
Because the DMF format reduces the gap between sectors on a disk,
low-quality or older disk drives may have trouble reading the disk.
Any utility, or computer virus, that writes an MS-DOS type of master
boot record on the disk will render any DMF data on the disk unusable.

END Extract from the 'Microsoft Solutions Development Kit 2.0'