DOSBox-X Built-In Programs on the Virtual Z: Drive

DOSBox-X provides a virtual read-only drive Z: that is always present and contains all of its built-in utility programs. These programs are embedded directly in the DOSBox-X executable — no installation is required and they cannot be accidentally deleted. They are organised into subdirectories on Z: such as Z:\SYSTEM\, Z:\DOS\, Z:\BIN\, and Z:\DEBUG\. This page documents the most important programs you will use during regular emulation.

The Z: drive is always the last drive letter. To see everything available, run DIR Z:\ /S /B from the DOSBox-X shell.

Disk & Drive Management

MOUNT

Mount a host directory or physical device as a DOS drive inside DOSBox-X. This is one of the most frequently used programs — it is how you make your real files accessible from inside the emulator.

MOUNT <drive> <hostpath> [-t <type>] [-label <label>] [-freesize <mb>]
      [-ro] [-nocachedir] [-q]
MOUNT -u <drive>
MOUNT

Examples
Options

MOUNT C C:\dosgames
MOUNT D "D:\My CD Games" -t cdrom
MOUNT A A:\ -t floppy
MOUNT E ~/overlay -t overlay
MOUNT -u C
MOUNT

Option	Description
`-t <type>`	Drive type: `dir` (default), `floppy`, `cdrom`, `overlay`
`-label <label>`	Set the volume label of the mounted drive
`-freesize <mb>`	Report this many megabytes as free space
`-ro`	Mount read-only
`-nocachedir`	Disable directory caching
`-u`	Unmount the specified drive
`-q`	Quiet mode (suppress success messages)

Mounting a drive with -t cdrom enables CD audio and Joliet/ISO 9660 handling. Without this flag, ISO features will not work even if the directory contains .cue or .iso files.

Running MOUNT with no arguments lists all currently mounted drives and their types.

IMGMOUNT

Mount a disk image file (floppy, hard disk, or CD-ROM) as a DOS drive. Supports raw .img, .ima, .iso, .cue/.bin pairs, and more.

IMGMOUNT <drive> <imagefile> [-t <type>] [-fs <filesystem>]
         [-size <ss,h,c>] [-ide <pos>] [-ro] [-q]
IMGMOUNT <drivenumber> <imagefile> [-t hdd|floppy|cdrom]
IMGMOUNT -u <drive>
IMGMOUNT

Examples
Options

IMGMOUNT A floppy.img -t floppy
IMGMOUNT A disk1.img disk2.img disk3.img -t floppy

Option	Description
`-t <type>`	Image type: `hdd`, `floppy`, `cdrom`
`-fs <fs>`	Filesystem hint: `fat`, `iso`, `none`
`-size <ss,h,c>`	Override sector size, heads, and cylinders
`-ide <pos>`	Attach to IDE controller position (e.g., `1m`, `1s`, `2m`)
`-ro`	Mount read-only
`-q`	Quiet mode
`-u`	Unmount drive

When mounting multiple floppy images at once (disk-swapping sets), pass them all on one command line. You can then swap between them using the DOSBox-X menu or hotkey.

Running IMGMOUNT with no arguments shows all currently mounted image drives and their status.

IMGMAKE

Create a new blank disk image file suitable for use with IMGMOUNT. Supports a range of standard floppy formats and arbitrary hard disk sizes.

IMGMAKE <filename> -t <type> [-size <mb>] [-nofs] [-source <drive>]

Examples
Disk Types
Options

IMGMAKE floppy.img -t fd_1440
IMGMAKE old.img   -t fd_360
IMGMAKE hd720.img -t fd_720
IMGMAKE hd12.img  -t fd_1200
IMGMAKE hd288.img -t fd_2880

Type	Format
`fd_360`	5.25″ 360 KB floppy
`fd_720`	3.5″ 720 KB floppy
`fd_1200`	5.25″ 1.2 MB floppy
`fd_1440` (or `fd`, `floppy`)	3.5″ 1.44 MB floppy
`fd_2880`	3.5″ 2.88 MB floppy
`hd`	Hard disk image (use `-size` to specify MB)

Option	Description
`-t <type>`	Disk type (see table)
`-size <mb>`	Hard disk size in megabytes
`-nofs`	Create image without formatting a filesystem
`-source <drive>`	Copy from a real floppy drive (physical read)

IMGSWAP

Swap between disk images in a multi-image set that was loaded via IMGMOUNT.

IMGSWAP [drive] [slot]

IMGSWAP A
IMGSWAP A 2

BOOT

Boot from a disk image file or from an emulated drive. Use this to run operating systems that require booting from a floppy or hard disk image (e.g., bare DOS, Windows 3.x booters, or custom OS images).

BOOT <imagefile> [-t floppy|hdd]
BOOT -l <drive>

Examples
Options

BOOT boot.img
BOOT -l C
BOOT floppy.img -t floppy

Option	Description
`-l <drive>`	Boot from the specified mounted drive letter
`-t floppy`	Treat the image as a floppy disk
`-t hdd`	Treat the image as a hard disk

Once BOOT hands control to the image, DOSBox-X’s built-in DOS kernel is bypassed. The Z: drive and all built-in programs will no longer be accessible until the session is reset.

Configuration

CONFIG

Read or write DOSBox-X configuration values at runtime, or save the current configuration to a file. This is the primary way to change emulator settings from within the DOS shell without restarting.

CONFIG -get <section> <property>
CONFIG -set <section> <property>=<value>
CONFIG -wc [filename]
CONFIG -all -wc [filename]
CONFIG -l
CONFIG -r [filename]

Examples
Options

CONFIG -get dosbox memsize
CONFIG -get render scaler
CONFIG -l

Option	Description
`-get <section> <prop>`	Print the current value of a property
`-set <section> <prop>=<val>`	Set a property value immediately
`-wc [file]`	Write changed settings to a config file
`-all -wc [file]`	Write all settings (including defaults) to file
`-l`	List all sections and properties
`-r [file]`	Restart DOSBox-X, optionally loading a new config
`-wcd`	Write config to the default user config path

Memory & Compatibility

LOADFIX

Allocate a block of conventional memory below the 64 KB boundary to work around programs that incorrectly assume low memory is free. This is often needed for old DOS games that crash because DOSBox-X’s environment data occupies the lowest memory addresses.

LOADFIX [-<kb>] [program] [args]
LOADFIX -f

Examples
Options

LOADFIX program.exe
LOADFIX -64 program.exe
LOADFIX -128 game.exe /fast
LOADFIX -f

Option	Description
`-<kb>`	Allocate this many kilobytes below 64 KB (default 64)
`-f`	Free all previously allocated LOADFIX memory blocks
`-xms`	Allocate from XMS instead of conventional memory
`-ems`	Allocate from EMS instead of conventional memory

If a game crashes immediately with a memory error or produces garbage output, try LOADFIX game.exe before filing a compatibility report.

Drive Utilities

RESCAN

Force DOSBox-X to refresh its internal directory cache for a mounted drive. Use this after adding, removing, or modifying files from the host side (outside of DOSBox-X) while the drive is mounted.

RESCAN
RESCAN <drive:>
RESCAN /A

RESCAN
RESCAN C:
RESCAN /A

/A rescans all mounted drives at once.

LABEL

Set or change the volume label of a mounted drive.

LABEL [drive:] [label]

LABEL C: MYGAMES
LABEL D:

Keyboard & Input

KEYB

Change the active keyboard layout. DOSBox-X includes built-in support for a wide range of international keyboard layouts using the standard two- or three-letter country codes.

KEYB [layout] [codepage] [codepagefile]
KEYB

Examples
Common Layout Codes

KEYB
KEYB DE
KEYB FR 850
KEYB UK
KEYB US

Code	Layout
`US`	United States (default)
`UK`	United Kingdom
`DE`	Germany
`FR`	France
`ES`	Spain
`IT`	Italy
`NL`	Netherlands
`PL`	Poland
`RU`	Russia

Running KEYB with no arguments displays the current keyboard layout and code page.

MOUSE

Control mouse capture and driver behaviour inside DOSBox-X.

MOUSE [/U] [/V]

Option	Description
`/U`	Uninstall the DOSBox-X internal mouse driver
`/V`	Display mouse driver version information

Display & Output

MODE

Configure display settings, code pages, and serial port parameters. Mirrors the functionality of the classic DOS MODE command.

MODE CON COLS=<n> LINES=<n>
MODE CON CP SELECT=<codepage>
MODE COM<n> BAUD=<rate> PARITY=<p> DATA=<d> STOP=<s>
MODE LPT<n>

MODE CON COLS=80 LINES=25
MODE CON CP SELECT=437
MODE COM1 BAUD=9600 PARITY=N DATA=8 STOP=1

MIXER

Adjust the volume levels and settings of DOSBox-X’s internal audio mixer from the command line.

MIXER [channel] [volume] [/LISTMIDI] [/NOSHOW]

MIXER
MIXER MASTER 80
MIXER SB 100:100
MIXER /LISTMIDI

System Information

INTRO

Display the DOSBox-X introduction screen with basic usage instructions and tips. Useful for new users.

INTRO
INTRO MOUNT
INTRO CDROM
INTRO SPECIAL

Running INTRO with a topic name shows specific help pages.

HELP

Display the built-in help listing all available shell commands (also accessible as a shell command directly).

HELP [command]
HELP /ALL

Text Mode Utilities

DOSBox-X includes several small programs on Z:\TEXTUTIL\ for switching the display into different text video modes:

Program	Mode
`80X25.COM`	80×25 text mode
`80X43.COM`	80×43 text mode (EGA)
`80X50.COM`	80×50 text mode
`80X60.COM`	80×60 text mode
`132X25.COM`	132×25 wide text mode
`132X43.COM`	132×43 wide text mode
`132X50.COM`	132×50 wide text mode
`132X60.COM`	132×60 wide text mode
`DCGA.COM`	Double-scanned CGA mode

Debug & Development Utilities

VFRCRATE — Video frame rate control

Control or query the emulated video frame rate.

VFRCRATE [rate]

VESAMOED — VESA mode editor

View and edit VESA BIOS extension (VBE) mode parameters. Available when a SVGA or VESA machine type is active.

VESAMOED

A20GATE — A20 line control

Control the A20 address line gate, used for compatibility testing with memory managers and extended memory code.

A20GATE [ON|OFF|TOGGLE|PORT|FAST|MASK]

NMITEST — NMI test

Trigger a Non-Maskable Interrupt for hardware-level debugging.

NMITEST

BIOSTEST — BIOS test

Run a diagnostic test against the emulated BIOS.

BIOSTEST

INT2FDBG — INT 2Fh debugger

Enable logging of INT 2Fh multiplex interrupt calls to help debug TSR and network redirector interactions.

INT2FDBG [+|-]

Additional Z: Drive Executables

Beyond the programs above, DOSBox-X bundles a set of standard DOS utilities as pre-built executables embedded in the Z: drive. These are found in Z:\DOS\, Z:\BIN\, and related directories:

DOS Utilities (Z:\DOS\)
General Utilities (Z:\BIN\)
System Programs (Z:\SYSTEM\)

Program	Description
`DEBUG.EXE`	Classic DOS debug utility for machine-code debugging
`EDLIN.EXE`	Line-by-line text editor (classic DOS editor)
`EDIT.COM`	Full-screen text editor
`FIND.EXE`	Search files for text strings
`MEM.EXE`	Display conventional, extended, and expanded memory usage
`MOVE.EXE`	Move files from one location to another
`SORT.EXE`	Sort input lines and output the result
`XCOPY.EXE`	Copy files and directory trees
`REPLACE.EXE`	Replace files in a target directory from a source
`APPEND.EXE`	Append directories to the search path for data files
`FC.EXE`	Compare two files and display differences
`COMP.COM`	Compare two files byte-by-byte
`DELTREE.EXE`	Delete a directory tree recursively
`CHOICE.COM`	Interactive user-choice prompt
`TREE.COM`	Display directory tree structure
`FCBS.COM`	Set the number of FCB (File Control Block) entries
`FILES.COM`	Set the maximum number of open files
`LASTDRIV.COM`	Set the last drive letter available
`DEVICE.COM`	Load a device driver
`BUFFERS.COM`	Set the number of disk buffers
`SYS.COM`	Transfer DOS system files to a disk (non-PC98 only)
`FORMAT.EXE`	Format a disk (non-PC98 only)
`DEFRAG.EXE`	Defragment a disk (non-PC98 only)
`DISKCOPY.EXE`	Copy floppy disk to floppy disk
`PRINT.COM`	Background print spooler
`KEYB.COM`	Change the active keyboard layout
`MODE.COM`	Configure display, serial, and parallel ports
`MOUSE.COM`	Control mouse capture and driver behaviour
`LOADFIX.COM`	Allocate low memory to fix compatibility issues
`LABEL.COM`	Set or change a drive volume label

Program	Description
`LS.COM`	Unix-style directory listing
`ADDKEY.COM`	Inject keystrokes into the input buffer
`COLOR.COM`	Set console foreground/background colours
`TITLE.COM`	Set the DOSBox-X window title
`VHDMAKE.COM`	Create VHD (Virtual Hard Disk) image files
`AUTOTYPE.COM`	Automatically type text into the DOSBox-X console
`UTF8.COM`	UTF-8 encoding utility
`UTF16.COM`	UTF-16 encoding utility
`ZIP.EXE`	Create ZIP archives (non-PC98 only)
`UNZIP.EXE`	Extract ZIP archives (non-PC98 only)
`CWSDPMI.EXE`	DPMI host for running protected-mode DOS programs (non-PC98 only)
`DOS32A.EXE`	Alternate DOS/32A DPMI extender (non-PC98 only)
`DOS4GW.EXE`	DOS/4GW DPMI extender used by many games (non-PC98 only)
`DOSIDLE.EXE`	DOS idle program to reduce CPU usage (non-PC98 only)
`FDISK.EXE`	Partition a hard disk (non-PC98 only)
`EVAL.EXE`	Expression evaluator
`SETCOLOR.COM`	Set CGA/EGA palette colours
`SHUTDOWN.COM`	Shut down DOSBox-X from within DOS (non-PC98 only)

Program	Description
`MOUNT.COM`	Mount host directories as DOS drives
`IMGMOUNT.COM`	Mount disk image files
`IMGMAKE.COM`	Create new disk image files
`IMGSWAP.COM`	Swap disk images in a set
`BOOT.COM`	Boot from disk image or drive
`CONFIG.COM`	Read/write DOSBox-X configuration
`COUNTRY.COM`	Set country/locale code
`RESCAN.COM`	Refresh drive directory cache
`CFGTOOL.COM`	Launch the GUI configuration tool
`MIXER.COM`	Adjust audio mixer levels
`SERIAL.COM`	Configure serial port emulation
`PARALLEL.COM`	Configure parallel port emulation
`CAPMOUSE.COM`	Capture/release the mouse cursor
`HELP.COM`	Display shell command help
`INTRO.COM`	Show DOSBox-X introduction
`START.COM`	Launch host programs (when `hostrun` is enabled)
`FLAGSAVE.COM`	Save/restore emulation state flags
`RE-DOS.COM`	Restart the DOS kernel

The exact set of programs available on Z: depends on the machine type selected and the DOSBox-X build configuration. Some utilities (such as VESAMOED.COM) only appear when an appropriate machine type is active.

Command-Line Options

DOS Commands

Configuration Reference

Building & Contributing

DOSBox-X Built-In Programs on the Virtual Z: Drive

Disk & Drive Management

MOUNT

IMGMOUNT

IMGMAKE

IMGSWAP

BOOT

Configuration

CONFIG

Memory & Compatibility

LOADFIX

Drive Utilities

RESCAN

LABEL

Keyboard & Input

KEYB

MOUSE

Display & Output

MODE

MIXER

System Information

INTRO

HELP

Text Mode Utilities

Debug & Development Utilities

Additional Z: Drive Executables

Build docs developers (and LLMs) love

Command-Line Options

DOS Commands

Configuration Reference

Building & Contributing

Documentation Index

​Disk & Drive Management

​MOUNT

​IMGMOUNT

​IMGMAKE

​IMGSWAP

​BOOT

​Configuration

​CONFIG

​Memory & Compatibility

​LOADFIX

​Drive Utilities

​RESCAN

​LABEL

​Keyboard & Input

​KEYB

​MOUSE

​Display & Output

​MODE

​MIXER

​System Information

​INTRO

​HELP

​Text Mode Utilities

​Debug & Development Utilities

​Additional Z: Drive Executables

Build docs developers (and LLMs) love

Disk & Drive Management

MOUNT

IMGMOUNT

IMGMAKE

IMGSWAP

BOOT

Configuration

CONFIG

Memory & Compatibility

LOADFIX

Drive Utilities

RESCAN

LABEL

Keyboard & Input

KEYB

MOUSE

Display & Output

MODE

MIXER

System Information

INTRO

HELP

Text Mode Utilities

Debug & Development Utilities

Additional Z: Drive Executables