	     COPYRIGHT (c) 1994 WESTERN DIGITAL CORPORATION
			    WDCDRV.DOC
		    READ ME FILE FOR WDCDRV.386

WDCDRV.386
Version:    2.5
Date:       6/17/94
Size:       16,475 BYTES

CAVIAR.EXE
Version:    1.1
Date:       8/22/94
Size:       54,384

1.1 Overview

WDCDRV.386 is a "Fastdisk" hard disk driver for use under Microsoft's  Windows
3.1 on 386 or higher based systems. Its main benefit is its ability  to transfer
data from the hard disk in either a Block Mode PIO fashion, EISA type 'B' DMA
fashion, or PCI type 'F' fashion.

CAVIAR.EXE is a configuration program that allows the user to change the option
settings for WDCDRV.386 through a Windows program. This program makes it
unnecessary for the user to edit SYSTEM.INI directly to change the options that
WDCDRV.386 reads from the [WDCDRV] section of that file. It also will reduce the
possibility of the user making invalid edits or damaging his SYSTEM.INI while
manually editing it. During installation, the setup program creates a program
group and icon for executing this configuration program. The program includes
on-line help for operating the program as well as the purpose of each option
setting.  Reviewing this help information is highly recommended.

1.2 WDCDRV Features

WDCDRV implements several enhancements to the basic *WDCTRL Fastdisk driver
shipped with Windows 3.1. The subsections that follow contain summaries of
these features. For more detailed descriptions of the related options for each
feature see section 3.x.

1.2.1 Block Mode PIO

Block Mode PIO is a means of transferring multiple sectors at a time between 
the host and hard disk as opposed to transferring one sector at a time. 
Normally in an AT compatible machine a hardware interrupt occurs for each 
sector transferred to/from the hard disk. Under Block Mode PIO one interrupt 
will occur for a block of sectors. The number of sectors that are to be 
transferred per interrupt is programmable by the host and is referred to as 
the blocking factor. The driver will determine if block mode is enabled for 
the drive when you start Windows. If block mode is detected then the blocking 
factor programmed is used as the default value for the Fastdisk driver. If 
block mode was not enabled for the drive when Windows was started the default 
blocking factor used equals the maximum blocking factor supported that is 
reported by the drive on an Identify Drive command.

Transferring data via Block Mode PIO increases throughput by eliminating the
inter-sector overhead associated with each sector. This is most beneficial when
the hard disk is transferring data out of its cache.  Block Mode data transfers
are enabled by default.

1.2.2 DMA Transfers

Transferring drive data via DMA allows the host CPU to work on other tasks
while hard disk data transfers are taking place. This increases the overall CPU
bandwidth which is critical in multi-tasking environments.

This driver only runs Block Mode PIO and DMA on Western Digital drives. To use
the DMA feature the drive must be installed in an EISA or PCI  system and the
DMARQ and DMACK- signals on the the 40 pin cable must be  connected to the
proper DMA request and acknowledge signals on the EISA  or ISA bus.

This revision of WDCDRV drive automatically detects DMA channel and system bus
type being EISA, PCI/ISA or PCI/EISA.

1.2.2.1 EISA Type B DMA

This driver also supports EISA type 'B' DMA transfers for drives that support
this feature and are installed in an EISA system. Data is transferred at a rate
of 4 MB/sec which is about double that of a 6 MHz AT. The standard Read DMA and
Write DMA commands as described in the CAM ATA specification are used.

1.2.2.2 PCI Type F DMA

Furthermore, type 'F' DMA is supported in PCI based systems. Data is
transferred at a rate of between 6 and 8 MB/sec using type 'F' DMA. The same
Read DMA and Write DMA op codes are used, the only difference is in the
programming of the DMA controller on the motherboard.

1.2.3 Translating BIOS

Translating BIOS allows use of IDE drives larger than 528 megabytes. When a
translating BIOS is present the standard *WDCTRL will not load and operate. The
WDCDRV.386 program recognizes and functions correctly with translating BIOS. In
addition many translating BIOS use logical block addressing (LBA) which is also
incompatible with *WDCTRL. If a drive is capable of LBA operation then LBA mode
will always be used.

1.2.4 Disk Manager Compatibility

Use of Ontrack Disk Manager prevents operation of *WDCTRL since Disk Manager
performs translation and other activities which cause *WDCTRL to be become
non-functional. Versions of WDCDRV later than 2.3 will detect and operate with
Disk Manager version 6.03.

2.1 Notes on Operation

There are several issues related to operation of the driver that the user may
need to be aware of. These are detailed in this section and may cover potential
incompatibilities or may simply be more detailed information on driver operation
or installation.  Not all information will be needed by every user and may often
be skipped or ignored.

2.2 Known Problems

2.2.1 MS-DOS 5.0 EMM386.EXE

This driver will not operate with the version of EMM386.EXE supplied with
MS-DOS 5.0.  This version should not be in use since Windows 3.1 setup will
replace the lines in CONFIG.SYS to load HIMEM.SYS and EMM386.EXE with lines to
load these files from the Windows directory.  New versions of these files
supplied with Windows 3.1 operate correctly with WDCDRV.386. The versions of
EMM386.EXE supplied with MS-DOS 6.0 and MS-DOS 6.2 have also been verified to
operate correctly with WDCDRV.386.

2.3 Technical Information

2.3.1 LBA Mode Operation

The driver will always operate in LBA mode if the drive is capable of using LBA
mode commands. This reduces overhead in the driver and the drive firmware
slightly and will not impact drive operation in any other way.

2.3.1 Temporary Swap Files

When Windows is configured for a temporary swap file it performs accesses to
that swap file through the PC BIOS. A potential conflicts between one blocking
factor being used for swap file accesses by the BIOS and another blocking factor
being used by all other Windows disk accesses the driver requires special
processing by the driver.  Thus the driver will not allow the blocking factor to
be changed from that selected by the BIOS when a temporary swap file is in use
by Windows.  Any attempt to change the blocking factor in the SYSTEM.INI file
will be ignored.  The driver will continue to use block mode transfers using the
blocking factor selected by the system BIOS at power-on.

3.1 Installation Instructions

You must have Windows 3.1 installed on your hard disk prior to performing any 
installation of the WDCDRV.386 driver. You then have two methods for 
installation of the driver.  The first, and recommended, method is the 
automatic installation procedure which only requires you to run the SETUP.EXE 
utility from Windows 3.1. This SETUP.EXE and the associated files are located 
on the distribution floppy containing the WDCDRV.386 driver. Information on 
running the automated installation procedure can be found in the README.DOC 
file on the WDCDRV.386 distribution floppy. The second method is manual 
installation of the driver program only. The CAVIAR.EXE configuration program 
and its associated help files are not installed by this procedure. You must 
use the automated procedure to install these files if you wish to use them.

3.1.2 Manual Installation Procedure

	1. Copy WDCDRV.386 to the Windows directory of your hard disk. This 
       directory is normally C:\WINDOWS but may be different for your system
       configuration.
	2. Edit the SYSTEM.INI file as follows:

		OLD:                            NEW:

		[386Enh]                        [386Enh]
	device=*wdctrl                  REM device=*wdctrl
					device=c:\windows\wdcdrv.386

	Putting a 'REM' in front of "device=*wdctrl" will cause Windows to  ignore
    this line. The second statement defines the path to the  Western Digital
    driver WDCDRV.386 which is replacing the wdctrl  FastDisk driver from
    Microsoft. If WDCDRV.386 is not in the c:\windows  directory then simply
    type in the proper path to its location in the  device statement.

	3. Run Windows and select the "Control Panel" icon. Then select the
	   "386 Enhanced" icon. Next select the "Virtual Memory..." option.
	   Select "Change>>" and then check the "Use 32-bit Access" option.
	   The "Use 32-bit Access" option must be on in order for the 
	   WDCDRV.386 FastDisk driver to be loaded. Windows will reboot and 
	   WDCDRV.386 will become active.


>>>>>>  IF you do not see 32 bit Disk access flag displayed at above window
	Please enter following lines in [386Enh] section of system.ini file:

	[386Enh]
	32BitDiskAccess=ON / Off
	device=*int13
	device=C:\WDCDRV.386
>>>>>>>

	             OPTIONAL SWITCHES:
	             ================== 

A new section called [wdcdrv] can be added in the SYSTEM.INI for optional
command line switches as follows:

    [wdcdrv]
    DMA=7
    DMATYPE=B

In this example, the DMA channel is set to 7 with type B DMA transfers. Since
DMA channel and transfer type are automatically detected during run time, these
switches are either redundant or provide an overide to what the driver would
otherwise use.

Please note that the [wdcdrv] section must come after the [386Enh] section in
SYSTEM.INI.

		         [WDCDRV] OPTIONAL COMMAND LINE SWITCHES

DMA=3, 5, 6 OR 7        Default is automatically detected by the driver.
                        This switch allows an overide of the DMA channel
                        that was automatically detected by the driver.

                        NOTE:

                        Please do not use this switch if you are not sure
                        what DMA channel is used for the IDE connector in 
                        your system. It is possible that there is no 
                        DMA Channel dedicated to the IDE connector.
 
DMAFLAG=ON / OFF        Default is ON. Can select OFF to turn off DMA. 

DMATYPE=F / B           Default is automatically determined by driver. This
                        switch allows an overide of the DMA type that was
                        automatically detected by the driver.

BLOCKINGFACTOR=4,8 or 16 This default value for this setting is automatically
                        determined by the driver. If the BIOS has enabled
                        block mode the driver will automatically use the
                        blocking factor programmed by the BIOS as the default.
                        If the BIOS did not program a blocking factor the
                        driver uses the value returned by the Identify Drive
                        command.  This switch allows an overide of the default
                        value chosen by the driver.



SCATTERGATHER=ON / OFF  Default is OFF. Can be enabled via this switch.

CSL=ON / OFF            Default is OFF. Required for Intel Express and 
                        Corsair systems when DMA channel 3 is being used. 
                        Configures DMA channel 3 properly.

