Subject: Re: floppy drives
To: None <>
From: Brian C. Grayson <>
List: port-i386
Date: 12/18/1996 16:16:03
Perry E. Metzger wrote:
> Darren Reed writes:
> > btw, is any work needed for the 120MB floppy drives ?
> The what?

  Check out -- I just
happened to stumble across this today.  At first I thought it was
a joke, because I had to traverse a few links from where I first
saw a link about 120MB floppies until I got to this page.  But
it makes (technological) sense to me.  I wonder how much the
special disks are going to cost, though...  :)

  Brief summary:  They etch a laser pattern on a track and
use that to allow them to accurately seek to 1700 tracks on a
side, and spin the disk faster (720rpm instead of 300(?)360(?))
to improve bandwidth.  They use a smaller read-write head so
that writing one track doesn't clobber the nearest 20 tracks :)
(and they have another head for 1.44 compatibility use).  A
special disk has to be used, for both the laser-etched and
laser-readable servo info and for the tight bit density.  They
claim max bandwidth of 500KB/sec (as in bytes), and the standard
62KB/sec when in 1.44 mode.

  On a related note, do the 1.44 and 2.88 floppy drives still use
MFM?  Are there any decent docs on the 765 controllers (or on any
other guts of the drive, such as the pinout of the 5-pin head
connector) on-line?  My searches have been fruitless so far.  I
was thinking about toying around a bit with a few old 360KB
drives I have lying around.

Brian Grayson (
Graduate Student, Electrical and Computer Engineering
The University of Texas at Austin
Office:  ENS 406       (512) 471-8011
Finger for PGP key.