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This article describes the command-line switches for Microsoft's CD-ROM Extension, Mscdex.exe, versions 2.21, 2.22, and 2.95.

Mscdex.exe is available from CD-ROM vendors, with the MS-DOS 6 Upgrade, 6.2 Upgrade, and 6.21 Upgrade, and with Windows 95/98.


Mscdex.exe is a CD-ROM "redirector." It hooks into the MS-DOS or Windows operating system the same way the network redirector does to obtain access to files that are not on local hard or floppy disks. As far as MS-DOS or Windows is concerned, CD-ROM drives look just like network drives. MSCDEX splices itself in front of the network redirector and takes requests belonging to CD-ROM drives and passes the rest to redirectors (such as network redirectors).

Command Line Switches

The following is the command line for MSCDEX.EXE:
MSCDEX.EXE: /D:x /M:n /E /V /L:x /S /K
The following table defines the MSCDEX.EXE command-line switches:
Switch                  Definition

/D:<device name>        - Allows you to specify a name for the device
                          driver. This name must be identical to the
                          device name used in the CONFIG.SYS file.

/M:<n>                  - Specifies the number of sector buffers used
                          to cache the path table of a CD-ROM disk.
                          Typically, each drive should have a minimum
                          of four to five buffers. The larger this
                          number is, the less your computer will have
                          to read directly from the CD-ROM drive.

/E                      - Tells MSCDEX.EXE to use expanded memory if
                          your system is using expanded memory.

/V                      - Displays information on memory usage
                          when you boot your PC.

/L:<drive letter>       - Allows you to specify the letter you want
                          to assign to the first CD-ROM drive.

/S                      - Allows the CD-ROM to be shared on MS-NET
                          based systems.

/K                      - Tells MSCDEX.EXE to use any KANJI (Japanese)
                          file structures, if present, rather than the
                          default of alphanumeric file structures.


Article ID: 87165 - Last Review: September 24, 2011 - Revision: 3.0
  • Microsoft Windows 3.0 Standard Edition
  • Microsoft Windows 95
kbinfo tp_cs KB87165

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