Using Microsoft CD-ROM Extensions

Using Microsoft CD-ROM Extensions

Microsoft CD-ROM Extensions (MSCDEX.EXE) is an executable program that works with the device driver (IBMIDECD.SYS) to enable the computer to read CDs as DOS-formatted disks.
MSCDEX is designed for DOS and Windows.

The CDSETUP program automatically adds an MSCDEX statement to the AUTOEXEC.BAT file.
You can modify the default MSCDEX parameters to customize the installation.
This section explains the function of each parameter.
Use a text editor to modify the MSCDEX statement in the AUTOEXEC.BAT file.

The following is the syntax of the MSCDEX.EXE entry in AUTOEXEC.BAT where [drive:][path]MSCDEX.EXE specifies the location (drive and directory) of the MSCDEX.EXE file.

         [drive:] [path]MSCDEX.EXE /D:device name
         [/M:n] [/E] [/V] [/L:drive letter]

(Do not truncate the actual device-driver entry. Place the complete entry on one line in the AUTOEXEC.BAT file.)

Use the following options to configure the device driver.

/D:device name 

This parameter specifies the name of the CD-ROM drive (eight characters maximum).
This name must be identical to the device name specified in the device driver in the CONFIG.SYS file.
For example:

         C:\MSCDEX.EXE /D:IBMCD1

You might support multiple CD-ROM drives (of different types) by installing each of their device drivers (naming them different names)
and placing a /D:device name statement in the MSCDEX line for each drive.
For example, if you want to support an IBM IDE CD-ROM drive and an IBM SCSI CD-ROM drive, the CONFIG.SYS file would have these statements:


and the AUTOEXEC.BAT file would include this statement:



This parameter specifies the number of sector buffers for temporary storage of the most recent CD data.
For example, to specify 12 sector buffers you would use:

         C:\MSCDEX.EXE /D:IBMCD1 /M:12
The CDSETUP program sets this value to 10. The default value for MSCDEX with no /M parameter is 4.

You can improve CD-ROM drive performance by using larger default values.
However, each buffer uses about 2 KB of memory, and too many buffer specifications might slow down the computer or interfere with other programs that have large memory-usage requirements.
You might be able to specify a larger number of buffers to enhance CD-ROM drive performance without adversely affecting programs that have large memory-usage requirements by using expanded memory (see the /E option in this section) or by loading MSCDEX.EXE into high memory using instructions given in the documentation that comes with the operating system or with the memory manager.


This parameter instructs the computer to use expanded memory, if available.
For example:

        C:\MSCDEX.EXE /D:IBMCD1 /E

Note that you must first load an expanded-memory device driver before using this option.
If no expanded-memory device driver is loaded, the following error message displays:

Expanded Memory not present or not usable.


This parameter instructs the computer to display a summary of RAM allocation and expanded-memory usage at startup time.

/L:drive letter 

This parameter specifies the drive letter to be assigned to the first CD-ROM drive.
Do not assign a letter already used by an existing drive or the computer will not be able to access the CD-ROM drive.
For example, you might use:

        C:\MSCDEX.EXE /D:IBMCD1 /L:F

Normally, DOS assigns the CD-ROM drive to the next available drive letter after devices such as diskette drives and hard disk drives.
Therefore, use this option only if you want to assign a drive letter beyond the last letter previously allocated by DOS.


This parameter instructs MSCDEX.EXE to use Kanji (Japanese) file structures, if present, rather than the default alphanumeric file structures.


This parameter instructs MSCDEX.EXE to allow networked computers to share CD-ROM drives.

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