                         VIRTUAL DISK

VDISK.SYS can be used to specify an optional virtual disk.  A virtual disk is
an area of computer memory set aside for data storage. You can store and
retrieve files from a virtual disk as if it were a real (physical) disk drive,
and it is much faster. When a virtual disk is defined, it is formatted during
the boot process when you turn on your computer, and a message will tell you
the assigned drive letter. External commands and BATCH files copied to a
virtual disk by AUTOEXEC.BAT execute quickly. Note: before turning off your
computer, you must copy any files on the virtual disk that you wish to keep to
a real disk. The contents of a virtual disk are lost when the computer is
turned off, or rebooted.

To set up a virtual disk, use an editor to add a line to the file CONFIG.SYS 
that looks like the one below. 

    DEVICE=[d:][pathname]VDISK.SYS [kbytes] [sectors] [d-entries] [/X[:m][/E:m]

<kbytes> is the number of kilobytes (thousands of characters) that the virtual 
    disk will contain. Minimum of 1, 64 is the default.
 
<sectors> is the sector size in bytes (characters). 128 is the default, 256
    and 512 can also be used.

<d-entries> is the maximum number of directory entries the virtual disk can 
    contain. Minimum of 2, maximum of 512, 64 is the default.

/E puts the virtual disk in extended memory. 

/X (/A on some systems) puts the virtual disk in expanded memory. This option 
    should probably not be attempted on most DOS systems prior to 4.0.

:m is the number of sectors to be transferred between extended/expanded memory
    and conventional memory without checking for interrupts. The default
    is 8. A smaller number may be needed. Only trial and error will tell you
    what the right number is for your computer. 

You may define more than one virtual disk by including more than one 
DEVICE=VDISK.SYS line in the CONFIG.SYS file. Any DEVICE=DRIVER.SYS lines 
should preceed all DEVICE=VDISK.SYS lines.
