Re: Can Linux read DMF format floppies?

ron@hottub.caldera.com
Tue, 20 Aug 1996 20:36:55 -0600 (MDT)

Linus Torvalds <torvalds@cs.helsinki.fi> wrote:
> On Tue, 20 Aug 1996, Ron Holt wrote:
> >
> > 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?
>
> Linux should be able to read them: there may even be a pre-set format for
> them.
>
> /dev/fd0H1680 (major 2, minor 44) should be a 21x2x80 3.5" floppy.

[...]

Thanks for the replies. Here's what my research shows...

DMF is 80x21x2, so /dev/fd0H1680 is the correct device. /dev/fd0 does not
seem to autodetect this type properly. Even after resetting the geometry
with the FDSETPRM ioctl I wasn't able to access the entire floppy via fd0.
I ended up opening /dev/fd0, determined the real geometry via FDGETPRM,
closed /dev/fd0 and opened the appropriate device (/dev/fd0H1680, for example).

BTW, this work now allows Wabi for Linux to install things like Excel 5.0c and
other applications that Microsoft distributes in DMF. Sun has been doing
some testing of our port of Wabi for Linux and alerted us to this issue.

(Also, simply mounting /dev/fd0H1680 seems to work fine for reading at least).

Ron

--
Ron Holt <ron@caldera.com> Caldera, Inc.