Scott,

I am the author of the UIDE driver for DOS systems.   Eric Auer is
away from E-Mail, for a few days, so I will reply directly to your
thread about "Large drives with 4K sectors" --

First, DOS formatting programs are in effect "stand alone" utility
programs, that can pretty-much do what they like when formatting a
hard-disk.   Easy for them to format 512-byte sectors, 4K sectors,
or whatever.   But --

Second, file I-O done by other DOS programs uses either 24-bit CHS
requests (up through V6.22 MS-DOS) or 48-bit LBA requests (all new
DOS variants including FreeDOS).   The two I-O request schemes are
designed for 512-byte sectors only.   Thus, any program that wants
to do file I-O using new 4K-byte sectors will need MAJOR additions
in the DOS kernel to handle such I-O requests.   This "Ain't gonna
happen!", as some might say in the U.S.A.

Third, although a 48-bit disk logical-block address (LBA) could be
specified, DOS systems have not-yet gone beyond using more than 32
bits of "block count" (i.e. sectors) in a disk directory, limiting
DOS files (and disks!) to 2-TB maximum.   More than that will also
require MAJOR changes to the DOS kernel, and I believe this "Ain't
gonna happen, neither"!   DOS systems, excepting FreeDOS and maybe
EDR-DOS, are NOT under current maintenance, and any kernel changes
to most DOS variants are now only a "dream"!

If you desire to use a DOS system, I suggest you "Think only 2-GB"
drives, maximum.   If your system really NEEDS more than 2-GB, you
may want to consider reserving 2 or more "partitions" on the disk,
the first of which is limited to 2-GB for use with DOS.   I am not
a file-systems expert, so others shall have to tell you if DOS can
allow MORE than one 2-GB partition on the SAME disk.   I doubt it!

Since my own UIDE driver must handle all variants of DOS including
all "old" ones, I have NO plans to update UIDE specifically for 4K
sectors.   If "new" 4K-sector disks can still be handled via "old"
512-byte DOS I-O requests, I shall leave UIDE "as is".   UIDE thus
needs no changes to go above 2-TB, since it does issue all 48 bits
of disk LBA address for any hard-disk read or write command.

Jack Ellis


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