[Tfug] USB Floppy

[Bexley Hall]

Hi Angus,

--- On Fri, 12/4/09, Angus Scott-Fleming <angussf at geoapps.com> wrote:

> > Once in a great while, I have need of a 5" floppy drive.
> > I used to keep a machine with 3 & 5" drives in it just
> > for that purpose.  But, nowadays, the exposed drive bay is
> > worth more to me for other uses than a seldom used 5"
> > floppy drive!
> > 
> > But, it occurs to me that I *should* (?) be able to
> > bastardize a 3" USB floppy to hack together a 5"
> > floppy.  I.e., gut an external CDROM case; install
> > the 5" floppy with the smarts from the 3" USB
> > floppy and I *should* be able to read and write
> > 5" media (?).
> > 
> > Of course, this depends on how "universal" the "floppy
> > USB controller" guts are...
> 
> Well, since the 5-1/4" and 3-1/2" floppy cables both plug
> in to the same controller on the MB, I would think they would
> be very similar.

Yes.  Hence my suspicion that I *should* be able to do this...

> Been a long time since I actually handled a dual-floppy cable 
> but I'm sure I have a couple sitting around that you might be 
> able to look at to check pin-outs etc.

The only real difference is the connector that mates to the
drive.  E.g., 5" uses a double sided "edge" connector while
3" uses a dual row of pins (Berg style connector)

Actually, you can put 5" and 3" drives on an *8*" controller, too!
You just "omit" a group of signals in the center of the ribbon
when connecting to 3 or 5.

My concern is as to how much of the "FDC controller" is
exposed over the USB interface.  I.e., if the USB interface just
acts as a physical interconnect layer -- so, all the registers
in the controller would be visible in the host.  I suspect this
is *not* the case and the interface is at a much higher level
with more abstraction.  So, you would be limited as to what you
could do *with* the FDC controller once it is dangling off the 
end of the USB cable (i.e., the controller in the external drive
would limit the disk formats you could use, etc.)

> I have a Gateway 486 tower in my office which has both types of
> floppy.
> 
> > Comments?  Does this have a reasonable chance of working
> > (I'd hate to scrap an otherwise decent 3" USB floppy
> > just to discover it *won't* work...)
> 
> Googling turned up a fair number of people who are looking
> for things like this, I bet there would be a small market for it.

"*Small* market" is the key there!  ;-)