On Sun, 26 Apr 1998, Brian C. Grayson wrote:

: > No.  Zip disks and hard drives (basically one and the same with one
: > removable and one not) give a sector-by-sector interface to the CPU, not a
: > raw media interface where you can twiddle the format.  Additionally, the
: > encoding of modern hard drives is no longer MFM, and is much more set in
: > stone.
: 
:   The higher capacities I am discussing are independent of the
: actual physical encoding method (MFM, FM, GCR, RLL), and would
: benefit all such devices.  The savings are from converting
: <header gap data gap>^n into header gap <data>^n gap, i.e., using
: ``useless'' dead/idle space for data, and not with changing the
: lower-level bit format.

Where is this ``useless'' space coming from?

A SCSI or IDE (actually, ATAPI) disk gives a flat, 512 bytes per sector (or
whatever the disk's byte per sector count is), sector-mapped interface to
the computer.  The "header" and "data" you refer to is part of those disks'
(opaque) _encoding_.  You cannot change it, nor even touch the headers from
outside the disk. 

Whereas a floppy controller does the job of writing a sector header and
sector data individually to a floppy disk, modern hard disks just accept
sector data, period. 

-- 
-- Todd Vierling (Personal tv@pobox.com; Bus. todd_vierling@xn.xerox.com)