			  UDMA Driver for DOS
			  ~~~~~~~~~~~~~~~~~~~

This is a DOS driver intended to run ONLY a single UltraDMA hard disk
on chipsets made by VIA, Intel, SiS, ALi and other manufacturers. The
disk must be the master on the primary IDE channel. A primary slave is
assumed to be absent. Other IDE units (CD-ROM, ZIP, LS-120, etc.) must
use the secondary channel and are assumed to be run by other drivers.

An "identify drive" command is sent to the disk when the driver loads,
and the disk is set to its best UltraDMA mode with mode 2 (ATA-33) as
a default. If your controller doesn't support it, it can be limited by
a command line option. Disks from ATA-33 to ATA-133 may be used. The
driver handles only read and write requests to the primary master disk.
All other requests (seeks, etc.) are "passed" back to the BIOS or some
other driver for processing.

The disk is assumed to support standard LBA mode (63 sectors, 255 heads
and its "designed" number of cylinders). The driver supports 28-bit LBA
mode (BIOS commands 42h read, 43h write) and handles up to 128-GB disks
in MS-DOS v7.0+, PC-DOS 7.1 and FreeDOS. The old 24-bit CHS mode (BIOS
commands 2 read, 3 write) is still supported for MS-DOS v6.x and below.
CHS mode requires all user files to be on the first 8-GB of the disk.
More data, if present, must be in other disk partitions and accessed
via other operating systems which support LBA mode.

Version 2.0+ of this driver is changed so that if the user I/O buffer
is not DWORD-aligned, fails a VDS "lock" or crosses a 64K boundary, a
request shall be processed through a 4K driver buffer, using UltraDMA
I/O to and from the buffer. This prevents "passing" any I/O request
back to the BIOS for execution in slow PIO mode, as in older versions
of this driver. Not crossing a 64K DMA boundary is required by the Bus
Master IDE specification, and DWORD alignment - by the Intel chipsets.

The driver must be loaded by CONFIG.SYS after any XMS/UMB drivers, but
before any disk cache program, using the following line:

	DEVICE[HIGH]=[path]UDMA.SYS [Mode]

"Mode" is a digit from 2 to 6 to set an UDMA mode limit (default is 6).
Any slashes or dashes are optional, i.e. /4  -4  4  are all equivalent.
Unknown option characters are simply ignored without any error message.

Even if a maximum UDMA mode is specified, the UDMA mode will be set to
a LOWER value if the hard-disk cannot handle that maximum! For example
specifying /5 (ATA-100) on a hard-disk limited to mode 4 (ATA-66) will
cause the driver to set the disk to mode 4, the best the disk will do!
You don't normally need the Mode option - it will be automatically set
to the highest mode of your disk. However, if your controller does NOT
support it, you MUST specify the highest controller mode as an option!
Modes: 2 (ATA-33), 3 (ATA-44), 4 (ATA-66), 5 (ATA-100), 6 (ATA-133).
