DOS Command Mscdex
Type: External (6.0 and later)
Syntax:
MSCDEX /D:driver [/D:driver2. . .] [/E][/K][/S][/V][/L:letter]
[/M:number]
Purpose: Used to gain access to CD-ROM drives.
Discussion
MSCDEX can be loaded from your AUTOEXEC.BAT file or from the command
prompt to gain access to CD-ROM drives. The device driver that came
with your CD-ROM must be loaded from your CONFIG.SYS file. This
command should not be used after Windows has started.
Options
/D:driver1 [/D:driver2 . . .]
/D:driver specifies the driver signature of the first CD-ROM device
driver. This parameter must match the /D switch on the CONFIG.SYS
command that starts the corresponding CD-ROM device driver. The
MSCDEX command must include at least one /D switch.
/E - Specifies that the CD-ROM driver be allowed to use expanded
memory, if available, to store sector buffers.
/K - Specifies that DOS should recognize CD-ROM volumes encoded in
Kanji. By Default, MS-DOS does not recognize Kanji CD-ROM values.
/S - Enables sharing of CD-ROM drives on MS-NET or Windows for
Workgroups servers.
/V - Directs MSCDEX to display memory statistics when it starts.
/L:letter - Specifies the drive letter to assign to the first CD-ROM
drive. If you have more than one CD-ROM drive, MS-DOS assigns
additional CD-ROM drives subsequent available driver letters.
/M:number Specifies the number of sector buffers.
This page is from http://www.easydos.com. I pasted it on my website to avoid possible broken links. For further help with DOS commands, Check easydos.com out.