Provides access to CD-ROM drives.


MSCDEX [/E/K/S/V] [/D:driver ... ] [/L:letter] [/M:buffers]

/EForces the CD-ROM driver to use expanded memory, if available, to store sector buffers.
/KForces Dos to recognize CD-ROM discs encoded in Kanji.
/SEnables sharing of CD-ROM drives on networks
/VForces memory statistics to be displayed on start-up
/D:driverThe driver signature of the CD-ROM device driver (assigned when the device is loaded in config.sys).
/L:letterThe drive letter to assign to the first CD-ROM drive. If there is more than one drive, the additional drives are assigned subsequent available drive letters.
M:buffersThe number of sector buffers.


  1. The device driver for the CD-ROM drive must be loaded in Config.sys via a DEVICE or DEVICEHIGH command which must include a /D:driver parameter. This parameter assigns a driver name (or 'signature") to the CD-ROM device driver. The driver name is usually something along the lines of MSCD000. Each CD-ROM device driver being used must have a unique driver name.
    The device driver is specific to the drive and typically is supplied by the CD-ROM manufacturer on a floppy.

  2. The MSCDEX command must include a /D:driver parameter that matches the corresponding /D:driver parameter on the CD-ROM device driver's command line. MSCDEX uses the /D:driver to identify the correct CD-ROM device driver.

  3. MSCDEX can be run from autoexec.bat or at the command prompt but should not be used after Windows has started. If using SmartDrive, this should be loaded after MSCDEX. SmartDrive can significantly speed up the CD-ROM drive by read-caching it. By default, when SmartDrive loads, it checks for the presence of MSCDEX; if it is found, CD-ROM caching is enabled.

File Details

File NameDefault LocationDos Ver.Win Ver.SizeDateSource
Mscdex.exec:\windows\command 7.0Win95 25 473111/07/
7.1Win95 (OSR2.x) 25 473124/08/
Win98 25 473111/05/
Win98 SE 25 473123/04/

Superscripts denote which same size files, if any, are identical (using FC).

If you should have any comments or suggestions,
please contact: Bob Watson
This page last revised:
August 28, 2000.