Disk images
86Box supports a large variety of disk image formats for the emulated storage drives.
Hard disk images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Raw image |
Many |
Extensions include: .hdd .ima .img |
Japanese FDI |
.hdi |
|
.hdx |
||
Virtual Hard Disk |
.vhd |
Fixed, Dynamic and Differencing VHDs are supported through the MiniVHD library. |
Hard disk size limits
There are limits to how big of a hard disk an emulated machine can accept. Such limits will vary depending on the machine’s BIOS. The table below lists all important limits applicable to the IDE bus:
Limit |
Disk size |
Cylinders |
Heads |
Sectors |
|---|---|---|---|---|
20-bit CHS |
504 MB |
1024 |
16 |
63 |
12-bit cylinder |
2015 MB |
4095 |
16 |
63 |
ECHS translation |
4032 MB |
1024 |
128 |
63 |
Revised ECHS |
7560 MB |
1024 |
240 |
63 |
LBA translation |
8064 MB |
1024 |
256 |
63 |
16-bit cylinder |
32255 MB |
65535 |
16 |
63 |
28-bit LBA |
131071 MB |
65536 |
16 |
256 |
The maximum supported disk image size for IDE or SCSI is 131071 MB. Disk overlay software such as Ontrack Disk Manager can work around BIOS limits and allow booting of IDE hard drives within the 131071 MB limit, with the same caveats as using such software on a real machine.
Floppy disk images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Raw image |
Many |
Extensions include: .bin .dsk .flp .hdm .ima .img .vfd .xdf |
.86f |
Once loaded, any image can be converted to 86F through the status bar or Media menu. |
|
CopyQM |
.cq / .cqm |
|
DiskDupe |
.ddi |
|
EZ-DisKlone plus |
.fdf |
|
Formatted Disk Image |
.fdi |
Read only. |
HxC MFM |
.mfm |
Read only. |
ImageDisk |
.imd |
|
Japanese FDI |
.fdi |
|
PCjs JSON |
.json |
Read only. PCjs 1.0 format only; 2.0 not supported yet. |
Teledisk |
.td0 |
Read only. |
Floppy disk detection
86Box determines the physical media format (sides, tracks per side, sectors per track, bytes per sector) of a floppy disk image through the following methods:
Image file header data - not applicable for Raw and DiskDupe formats;
DOS BIOS Parameter Block data within the image;
If all else fails, a guess is made based on the image file’s size.
The BIOS Parameter Block detection method may behave incorrectly with non-DOS floppy disks. Installation floppies for UNIX and Linux are common examples of non-DOS disks. Disabling Check BPB is strongly recommended when accessing these, as an inaccurate BPB detection may result in read errors, data corruption and other issues.
Note
When using a Raw image of a non-DOS floppy with Check BPB disabled, make sure the image file is not truncated (smaller than its media size), otherwise incorrect behavior may still occur.
MO / ZIP removable disk images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Raw image |
Many |
Extensions include: .ima .img |
Japanese FDI |
.mdi / .zdi |
.mdi for MO, .zdi for ZIP. |
CD-ROM / DVD-ROM optical disc images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Cue sheet |
.cue + .bin |
|
ISO |
.iso |
CD audio
Compact Disc Digital Audio (CDDA) playback through the emulated CD-ROM drives is supported on Cue sheet images. Audio output is enabled on the first CD-ROM drive and muted on subsequent drives by default; individual drives can be muted or unmuted through the status bar or Media menu.
Note
Only raw format (.bin) tracks are supported. Compressed or otherwise encapsulated audio tracks (.wav, .mp3, .ogg, .flac and other formats) are not supported.
Cassette tape images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Raw PCM audio |
Many |
Extensions include: .pcm .raw Audio format must be unsigned 8-bit mono. |
PCE cassette |
.cas |
|
Wave audio |
.wav |
Audio format must be unsigned 8-bit mono. |
PCjr cartridge images
Supported formats:
Format |
File extension |
Notes |
|---|---|---|
Raw image |
Many |
Extensions include: .a .b .bin |
JRipCart |
.jrc |
Creating and using disk images
Disk images are a convenient way to transfer files in and out of your machine without the need to configure networking. Perhaps your OS doesn’t support networking or you don’t want to deal with the added complexity of configuring networking on legacy operating systems.
The tooling available varies by host operating system, ranging from command-line tools to full GUI.
Floppy: mtools (Linux, macOS)
The mtools suite is “a collection of utilities to access MS-DOS disks from GNU and Unix without mounting them.” With mtools you can create floppy disk images and copy files to the image. The resulting image can be mounted in 86Box. mtools can be installed via homebrew on macOS and is available in the standard package repositories on linux.
Warning
Never use a tool or utility to write to a disk image that is currently mounted by 86Box. Doing so can lead to unpredictable results, including filesystem corruption.
Creating floppy images
The following command will create a 1.4M (1440K, double-sided, 18 sectors per track, 80 cylinders) floppy image named floppy.img with a label of LABEL:
mformat -f 1440 -v LABEL -C -i floppy.img ::
The -f option specifies the format of the floppy being created. The command can be adjusted for format, label, and image name as needed.
Please see the mtools documentation for more information on the supported formats.
Copying files to floppy images
The following command will copy file1 and file2 to the floppy image floppy.img:
mcopy -i floppy.img file1 file2 ::
Wildcards are also supported with mcopy.
Note
The :: is required to let mtools know there are no more files to copy or arguments to process.
CD-ROM: macOS
macOS can natively mount CD-ROM ISOs, but to create them you’ll need to open up the terminal.
The following command creates an ISO file named cdrom.iso with the volume name CDROM.
hdiutil makehybrid -iso -joliet -joliet-volume-name "CDROM" -o /path/to/cdrom.iso /path/to/cd/root
In the above example the directory /path/to/cd/root becomes the root directory of the ISO image.
If you wanted your current working directory to be the ISO root filesystem you could use the following command:
hdiutil makehybrid -iso -joliet -joliet-volume-name "CDROM" -o ../cdrom.iso .
Note
Make sure the output filename with -o has a path outside of the filesystem root.
CD-ROM: Linux
Linux provides the mkisofs tool in order to easily create ISO images. The following command creates the ISO file cdrom.iso which contains the contents of the directory /path/to/cd/root:
mkisofs -o cdrom.iso /path/to/cd/root
Note
This package is available in the standard distribution repositories, generally under the mkisofs or genisoimage package names.
Disk Image: macOS
macOS can natively mount raw disk images (floppy or hard disk) of types FAT16 and FAT32. Simply double click the file in Finder to mount the image.
For fixed-size vhd files the following command may work depending your your macOS version:
hdiutil attach -imagekey diskimage-class=CRawDiskImage /path/to/your/vhd
Note
As with any image file in macOS, the image can only be mounted if macOS can read the underlying filesystem. macOS can read both FAT16 and FAT32.
Various: Windows
On Windows you can use WinImage to create and manipulate disk images.
Windows will also allow you to directly mount a vhd file in order to copy files. The Disk Management utility allows you to attach a vhd file by selecting Action -> Attach VHD from the menu.
Warning
As above, make sure that two different applications never mount the same image file simultaneously. For example, do not mount a vhd with Windows that is currently mounted by 86Box.
Windows also provides command-line functionality via the diskpart command. The documentation can located here.