UDMA drivers for DOS (Latest)

Getting old software/games running on older hardware.

UDMA drivers for DOS (Latest)

Postby johnsonlam » 2019-5-15 @ 07:53

It seems that the latest UltraDMA driver or DOS did not made popular in the forum, as I host the driver for over 10 years, I'm quite surprise.

The author Jack R. Ellis did notice some very outdated drivers talking around, the "UDMA 7.0" was seriously outdated and considered unstable.

If you go to <www.vogons.org> and do a search for "XHDD", note that the
two most recent posts refer to the old V7.0 UDMA driver, the last one I
did with Lucho in 2004. V7.0 UDMA is 15 years old and has these items
which are long-since CORRECTED in the current XHDD /B driver:

A) UDMA runs only one "legacy IDE" controller (up to 4 disk drives from
primary-master to secondary-slave). XHDD /B runs up to 14 disks
on up to 5 "legacy" and/or Native-PCI controllers.

B) UDMA does not check all possible PCI-bus "function" codes, only 4 of
the basic ones, so it may NOT find a controller to use. XHDD /B
tests ALL possible PCI-bus "function" codes.

C) UDMA runs only controllers that issue "Data request" before starting
an UltraDMA transfer. XHDD /B normally runs without expecting a
"Data request" but will run such old controllers with a /Q switch.

D) UDMA does NOT switch to its own stack upon entry. XHDD /B does so.

Items (A) and (B) make UDMA "useful" only for very early PC mainboards,
ones that had only the 4 "IDE" ports on 2 80-pin cables. Item (C) may
make UDMA fail on newer controllers that do NOT support "Data request",
like my own VIA VT8237 which is now over 10 years old.

Item (D) is now known to be a DISASTER, since there are some cases when
DOS systems have only about 40 stack bytes, e.g. when COMMAND.COM loads
a new program! Also, issuing VDS or XMS requests needs a minimum 256
stack bytes. UDMA cannot depend on having that much, when it must run
on the user's stack, or when it is "in between" programs!

The latest "Full feature" driver hosted on my personal web server:

Please download from my homepage, as it's official and original of all SATA CD-ROM/UltraDMA caching driver!
And I'll forward any question to the author, since he can't visit the forum.

Johnson Lam.
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Re: UDMA drivers for DOS (Latest)

Postby AvalonH » 2019-6-27 @ 18:05

Possible to get XHDD DMA working on motherboards that support USB legacy booting in DOS. The BIOS treats the USB hard disk as a fixed disk using Int13 and assigns number 0x80 with no device drivers in DOS needed. (INT13 +extensions as I have tried a 1TB USB drive single partition under DOS7.1 formatted with Fat32).
Handy on newer computers that all have NTFS drives and you boot dos via bios from USB HD or flash drive.
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Re: UDMA drivers for DOS (Latest)

Postby kalm_traveler » 2019-6-29 @ 14:19

this is only for IDE controllers?

I'm currently trying to find a way to get DOS (Windows 98SE or Me) to work with a PCI-E SATA II card in a PCI-E to PCI adapter. It works great in my PIII setup, but officially only supports Windows 2000 and newer (no 9x-based driver that I can find).

Chief reasons here are that it actually runs at SATA II speeds, compared to the existing PCI SATA I cards - and in theory it supports booting from CD/DVD drives (I could not find any native PCI SATA/SAS controllers which support this).
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Re: UDMA drivers for DOS (Latest)

Postby Rawit » 2019-7-01 @ 06:49

Tried this version and the previous version with all the switches, but it hangs after displaying HDD info. This is on the MediaGX platform which is notorious for its UDMA issues though.
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