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19.03.2010, 04:19

Improving USB transfer rate in DOS (Users)

Putting together a very basic box with an MSI G31TM-P35 board (chipset Intel G31 / Intel ICH7)... Booting DOS straight from a USB Flash drive is supported, but I'm experiencing *very* slow read and write transfer rates, less than 50 kb/sec. I assume the problem is legacy USB 1.0 support only in DOS mode, but even with this I should expect transfer rates of 500 kb/sec at least! The board of course has many USB 2.0 plugs. Even my Acer netbook with its puny Atom processor gives me straight DOS transfer rates of between 10 and 15 Mbytes / sec with the exact same 8 GB USB flash drive, which has been formatted in FAT32, 4kb cluster size!

Booting directly off a flash drive is nice, but what DOS drivers, if any, can be placed in Config.sys to improve performance? It must be an ICH7 chipset limitation. UIDE loaded but did not improve performance. It seems I read on this forum some time ago about USB 2.0 driver support in DOS, but now I can't find the thread.


19.03.2010, 04:36

@ Zyzzle

Poor USB transf rate when using UIDE driver and no idea why

> It must be an ICH7 chipset limitation.

BIOS ???

> UIDE loaded but did not improve performance.

What a surprise, considering that UIDE supports only IDE / ATA / SATA (non-AHCI) internal disks


> I read on this forum some time ago about USB 2.0 driver support in DOS
> but now I can't find the thread.


This is a LOGITECH mouse driver, but some software expect here
the following string:*** This is Copyright 1983 Microsoft ***



Fresno, California USA,
23.03.2010, 15:06

@ Zyzzle

UIDE Does Not Run USB Disk/CD/DVD Drives.

From my 2010-03-03 post on FD-User:

> At present, UIDE does not directly handle SCSI or USB hard
> disks, although if they are "declared" as BIOS units, UIDE
> "calls the BIOS" for their I-O and then caches their data,
> afterward. Sadly, most USB hard-disks are NOT "declared"
> as BIOS units, so UIDE may not be able to run them at all.

UIDE was originally a hard-disk IDE driver, from a time when
BIOS handling for such disks was non-existent or poor. But
IDE and UltraDMA "standards" did exist, so a "common" driver
for such disks, CD/DVD drives, and SATA (an IDE enhancement)
was possible. Adding caching into the original UDMA/XCDROM
driver logic has ultimately resulted in the current UIDE.

Regrettably, USB has at least two "standards", which COMPETE
with each other, and a "common" USB disk/CD/DVD driver would
demand adding too much logic in UIDE, if this is possible at
all! As I do not want UIDE to become "bloated" by a lot of
incompatible and competing "standards", I am in fact AGAINST
adding USB logic in the UIDE driver!

There are at least 2 solutions. First would be for writers
of BIOS logic to handle USB disk drives as actual BIOS units
just like hard-disks. UIDE would then "detect" one or more
non-PCI disks (i.e., the USB disks) and would cache them via
its "call the BIOS" logic. Not a "help" for CD/DVD drives,
which were never part of BIOS I-O and are always handled via
SHCDX33E/MSCDEX and the CD/DVD drivers, which includes UIDE.
But, BIOS support for USB hard-disks and maybe for a "memory
stick" is better-than-nothing, as UIDE would need NO changes
to cache their data automatically. [Periodically, I do try
loading UIDEJR /N2 (no CDs/DVDs) and then UIDE /N1 (no hard-
disk I-O) which makes UIDE use its "call the BIOS" logic for
disks. Disk I-O will get "intercepted" and done by UIDEJR.
Thus I am confident UIDE's "call the BIOS" logic does work!]

Second, existing USB drivers could be changed to detect that
UIDE is present, then they can invoke UIDE's "external call"
logic to achieve caching. I have never documented this, as
I am unaware of anyone ever trying to call UIDE for caching.
But, that logic is still present in UIDE, and if anyone ever
does want to call UIDE for caching, I would be happy to work
with them to achieve this. Such a scheme COULD support USB
CD/DVD drive caching, which should offer the same HUGE speed
increase as UIDE gives for SATA/IDE CDs and DVDs. When any
USB diskettes and other-type drives are present, they can be
cached by UIDE as well.

(Account disabled on user's request.)

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