LinuxWhat is the DMS file format?
.dms files are compressed floppy-disk images created using the Disk Masher System, developed by SDS Software for Commodore Amiga computers in the early 1990s. The disk is read block by block, so the data structure is copied accurately, producing a faithful sector-level replica of the original floppy.
.dms files were originally used on Amiga computers for archiving floppy-disk data. They enabled relatively easy sharing of disk images over the slow Internet connections of that era. Today, .dms files are used as disk images opened with software that emulates Amiga hardware, such as WinUAE or FS-UAE.
The Disk Masher is a proprietary archiving format with built-in compression and copy-protection schemes. However, the compression algorithm contained known errors that caused problems when storing certain bit sequences. Despite this drawback, .dms files were extremely popular in the Amiga scene, largely due to how easily demo software and warez could be distributed. Every genuine Amiga DMS image begins with the four-byte ASCII signature DMS! (hex 44 4D 53 21) at byte offset 0, distinguishing it from unrelated files that share the .dms extension.
Related floppy-image formats include the uncompressed .ADF, .ADZ (a gzip-compressed ADF), and .IPF for preservation-grade images; .dms archives were often distributed alongside .LHA archives on Amiga bulletin boards.
Security & safety
RISK: MEDIUMThe .dms container is passive data, but it's a DISK IMAGE of vintage Amiga software, so the real risks are: (1) running unknown Amiga software in an emulator - old cracks/intros could carry Amiga-era malware, harmless to your PC but it runs in the emulated Amiga; and (2) legal - many .dms files are copyrighted commercial Amiga games. Amiga Forever provides legally licensed ROMs/OS, and reputable Amiga preservation archives are the safest source.
Format details
in a nutshell- Exigen Workflow imaging file - A discontinued document-capture/imaging system stored scanned workflow images as .dms, readable only by that now-defunct software (the name carried in this site's old database).
- Domino MIDI sequence - The free Domino MIDI editor uses .dms for its sequence files.
- BYOND Dream Maker script - BYOND's Dream Maker game toolkit uses .dms for script files.
Programs that open DMS files
Windows3 apps
Amiga Forever
Paid Cloanto's all-in-one Amiga package; import/play the .dms directly with bundled, legally licensed Amiga ROMs/OS. 
WinUAE
Free The standard free Amiga emulator. Add the .dms (or its decompressed .adf) as a floppy disk image and boot the emulated Amiga. 
xDMS (dms.exe)
Open-source Command line: 'xdms u disk.dms' decompresses the image to a plain .adf you can mount in any emulator. 
macOS2 apps
The Unarchiver
Free Can recognise/extract some Amiga archive formats; use to inspect, then run the disk in an emulator.
FS-UAE
Open-source Cross-platform Amiga emulator; add the .adf (decompress the .dms first with xdms) as a floppy and boot. Technical details
deep spec| File signature | ASCII "DMS!" (hex 44 4D 53 21) at byte offset 0 |
| Format type | Binary compressed floppy-disk image |
| Developer | SDS Software (Disk Masher System) |
| Target platform | Commodore Amiga (AmigaOS) |
| Target media | Amiga 3.5-inch floppy disks; standard DD format is 880 KB (80 tracks × 2 sides × 11 sectors) |
| Compression modes | None, Simple (RLE), Fast, Medium, Deep, and Heavy - selectable at creation time |
| Known compression defect | Algorithm errors in certain versions caused data corruption for specific bit-sequence patterns |
| Copy-protection support | Embeds Amiga copy-protection data within the image structure |
| MIME type | application/octet-stream (no format-specific MIME type registered) |
| Standard | Proprietary, closed format; no public specification |
| Encoding | Binary; not human-readable |
| Related formats | .adf (uncompressed Amiga disk image), .adz (gzip-compressed ADF), .ipf (preservation-grade), .lha (common Amiga archive) |
| Extraction tool (CLI) | xdms - cross-platform command-line decompressor that converts .dms to .adf |
| Modern use | Retro computing and emulation; Amiga emulators (WinUAE, FS-UAE) load .dms files directly |
| Released | early 1990s (Disk Masher System, Commodore Amiga) |
| Specification | justsolve.archiveteam.org |
DMS conversions
Community Q&A
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