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From:	"Tim Nicholson" <djgpp AT gizzy DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Protected Mode disk access
Date:	Mon, 21 Jan 2002 17:45:50 -0000
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Am I correct in thinking the DJGPP switches from protected mode to real mode
to access the HDD and transfers data in 64K blocks (variable) via the DPMI
to and from DOS?

Is it not possible to access the HDD directly in protected mode via a FAT32
Library? - Does such a thing exist? and would it speed up disk I/O where
reasonable quantities (several MB) of data was been transferred to and from
the drive?

The reason for asking is that disk I/O seems much faster under Windows 98/ME
etc. and I am guessing this is partly because the whole thing is happening
in protected mode.

Does DOS (the one shipped with Win98) utilise the full capabilities of the
drive (i.e.. UDMA100 etc)?

Sorry for so many questions but my application is very disk intensive and
despite using smartdrive and my own cache routines to ensure that I only
load things if I don't already have them, I can't help thinking it should be
going much faster! I can't use Windows or Linux because the code must be
deterministic to meet certification requirments, besides, I like DOS!

Regards

Tim Nicholson

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