[comp.misc] Floppy drives and differing formats

keating@rex.cs.tulane.edu (John W. Keating) (12/10/90)

Why hasn't anyone come up with a floppy disk that can read and write in both
IBM and Macintosh (and Amiga, and ...) formats?  Is the hardware so different
that no one even wants to attempt it, or is it a matter of proprietory
hardware?

On the same note, why hasn't a 5.25 inch drive been created for the IBM that
can read and write in both 360K and 1.2M formats correctly?

It seems to me as if a drive that can do these things would be in high demand.

John

ekalenda@cup.portal.com (Edward John Kalenda) (12/11/90)

> Why hasn't anyone come up with a floppy disk that can read and write in both
> IBM and Macintosh (and Amiga, and ...) formats?  Is the hardware so different
> that no one even wants to attempt it, or is it a matter of proprietory
> hardware?

The problem is not the drive, it's the controller. There are two or three
companies which make controllers or controller/drive combos that let PCs
read/write MAC and MACs read/write IBM. I recall seeing one that dealt
with the Amiga. Almost any hardware oriented magazine or catalog will
have adds for them. The MAC SuperDrive can read and write PC 720K format
(and maybe 1.44M) using Apple File Exchange.

> On the same note, why hasn't a 5.25 inch drive been created for the IBM that
> can read and write in both 360K and 1.2M formats correctly?

When the 1.2M drive was created they used a much narrower head than on the
360K. This means that the area of each track written is much smaller on the
1.2M and much wider on the 360K. So, when a 360K tries to read a 1.2M track,
even at 360K formatting, it reads the track and the crud on the sides of the
track. 720K to 1.44M uses the same head, just a higher density and better
electronics. Too bad this isn't what they did for the 360K to 1.2M.

> It seems to me as if a drive that can do these things would be in high demand
.

It would be, but no single drive will be able to do it all because of the
head differences. But you can get close if you are willing to use a special
controller and software. And don't expect to boot from it. And are willing
to pay big for it.

> John

Ed
ekalenda@cup.portal.com