ID Number: Q75535
3.00 3.10
WINDOWS
Summary:
SYMPTOMS
In version s 3.0 and 3.1 of the Microsoft Windows graphical
environment, the Windows File Manager and the GetDriveType function
report that some network drives are local fixed drives.
CAUSE
In some releases of PC-DOS version 4.00 and MS-DOS version 4.01,
Interrupt 21h Function 4409h does not reliably return drive type
information.
RESOLUTION
The redirection entry list must store the local drive name in
uppercase letters.
More Information:
To work around the Interrupt 21h Function 4409h problem, Windows 3.0
or 3.1 recognizes that it is running on PC-DOS 4.00 or MS-DOS 4.01 and
uses Interrupt 21h Function 5F02h (Get Redir List Entry) to determine
if a drive is remote or local. Windows compares the drive index
(A = 0, B = 1, ..., Z = 25) to the drive index returned by the
function. Windows also assumes that the drive letter is uppercase.
If lpszLocal points to the "local" name returned by Get Redir List
Entry, Windows uses the following algorithm:
if ((lpszLocal[0] - 0x41) == wListIndex)
{
/** drive is remote **/
}
else
{
/** drive is fixed **/
}
Therefore, if the redirection entry list does not store the local name
in uppercase letters, and Windows 3.0 or 3.1 is running under PC-DOS
4.00 or MS-DOS 4.01, then the network drive will be reported as being
"FIXED."
Additional reference words: 3.00 3.10 VXDTSR