Provides access to CD-ROM drives. MSCDEX can be loaded from your AUTOEXEC.BAT file or from the command prompt. (The device driver that came with your CD-ROM drive must be loaded from your CONFIG.SYS file. For more information, see Notes.)
The MSCDEX command should not be used after Windows has started.
MSCDEX /D:driver [/D:driver2...] [/E] [/K] [/S] [/V] [/L:letter] [/M:number]
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Your CONFIG.SYS file must include a DEVICE or DEVICEHIGH command that loads the CD-ROM device driver that came with your CD-ROM drive. The CD-ROM driver's command-line should include a /D:drivername parameter. This parameter assigns a driver name (also called a driver signature) to the CD-ROM device driver.
The MSCDEX command must include a /D:drivername parameter that matches the /D:drivername parameter on the CD-ROM device driver's command-line. MSCDEX uses the /D:drivername parameter to identify the correct CD-ROM device driver. The driver name is usually a name similar to MSCD000. Each CD-ROM device driver currently in use must have a unique driver name.
The number of logical drive letters available on your computer can limit the number of CD-ROM drives you can have. The number of logical drives is determined by the LASTDRIVE command in your CONFIG.SYS file. By the time MSCDEX loads, some of the available drive letters might be used by other programs, such as a network, DriveSpace, or DoubleSpace.
If you use SMARTDrive, make sure the MSCDEX command appears before the SMARTDRV command in your AUTOEXEC.BAT file. SMARTDrive can significantly speed up your CD-ROM drive by read-caching it. By default, when SMARTDrive loads, it checks for the presence of MSCDEX; if MSCDEX is present, CD-ROM caching is enabled. For more information, see the SMARTDRV command.
Newer CD-ROM drivers, such as the OAKCDROM.SYS on the Windows 98 boot floppy and Mitsumi's IDE CD-ROM driver, only need one instance loaded in CONFIG.SYS to handle more than one drive, even if they're made by different companies. Many newer IDE/ATAPI CD-ROM drivers are able to handle more than one drive, listing them all and which brands/models each can handle would be too much work. I've yet to run into an IDE/ATAPI CD-ROM the Oak driver can't work with.
Likewise, the MSCDEX.EXE line in AUTOEXEX.BAT may only need one /D switch when using a device driver capable of handling more than one drive.
Needing a device driver for each CD-ROM drive and a /D switch for each was only required with the early proprietary Panasonic, Sony and Mitsumi interfaces and the early IDE drives. SCSI CD-ROMs may still require brand/model specific CONFIG.SYS drivers for each drive, if more than one drive brand/model is installed.
This example shows the relevant CONFIG.SYS and AUTOEXEC.BAT commands for a computer with one CD-ROM drive.
The CONFIG.SYS file contains the DEVICE command:
DEVICE=c:\devices\cdromdrv.sys /d:mscd000
This command loads the device driver CDROMDRV.SYS, which came with the CD-ROM drive. The AUTOEXEC.BAT file contains the MSCDEX command:
c:\dos\MSCDEX /D:mscd000 /E /L:g
This command enables the device driver that has the driver signature MSCD000. The /E switch specifies that the driver be allowed to use expanded memory, if available. The /L:G switch assigns the drive letter G to the CD-ROM drive.
This example shows the relevant CONFIG.SYS and AUTOEXEC.BAT commands for a computer that has two CD-ROM drives from two different manufacturers.
The CONFIG.SYS file contains the DEVICE commands:
DEVICE = c:\aspi\aspicd.sys /d:mscd000
DEVICE = c:\cdrom\tslcdr.sys /d:mscd001
Each command loads the device driver that came with that CD-ROM drive. The AUTOEXEC.BAT file contains the MSCDEX command:
c:\dos\MSCDEX /D:mscd000 /D:mscd001 /L:j
This command enables both device drivers. The first driver has the driver signature MSCD000; the second has the driver signature MSCD001. The /L:J switch specifies that the first CD-ROM drive, MSCD000, will be drive J and the second CD-ROM drive will be drive K.
Also see Newer drivers can be loaded once to handle multiple drives.
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