From DOSBoxWiki

MOUNT.COM is a command inside DOSBox that can connect physical folders and drives to virtual drives inside DOSBox. When you enter the command MOUNT from the DOSBox prompt you should see

Z:\>MOUNT
Current mounted drives are:
Drive Z is mounted as Internal Virtual Drive

To mount a folder as a drive, follow this basic template.

MOUNT [Drive-Letter] [Local-Directory]

To unmount a drive, follow this basic template.

MOUNT -u [Drive-Letter]

[edit] Usage Examples

[edit] Windows

[edit] Mounting a folder from your harddrive

Z:\>MOUNT C C:\DOSGAMES

[edit] Mounting a floppy drive

Z:\>MOUNT A A:\ -t floppy

[edit] Mounting a CD-Rom drive

Z:\>MOUNT D D:\ -t cdrom

[edit] Extra CD ROM options

-t [floppy|cdrom] Define how the mounted folder should behave to the emulated operating system.
-usecd [drive #]  For direct hardware emulation ie: audio playback, etc.
-cd = Generate a list of local CD ROM drive's "drive #" values
-label [name] = Set the volume name of the drive (all caps)
-ioctl = Lowest level of hardware access (Win 2K, XP and Linux)...follows the -usecd command

Z:\>MOUNT D D:\ -t cdrom -usecd 0 -ioctl -label GAME_CD

[edit] Mounting an ISO-File as volume

Z:\>IMGMOUNT E C:\Images\MyImage.iso -t iso

[edit] Linux

Z:\>MOUNT C ~/DOSGAMES

[edit] Mac OSX

Z:\>MOUNT C ~/DOSGAMES

Z:\>IMGMOUNT D ~/Documents/IMAGE.toast -t iso

[edit] Using your mounted drive

To change to the newly mounted virtual drive simply type

[Drive-Letter]:

For example (If you mounted a Local-Directory to the Drive-Letter C)

Z:\>C: