DDI File

What are DDI files and how to open them

Are you having problems opening a DDI file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your DDI files.

What is a DDI file?

A .DDI file is a DiskDupe Disk Image file.

DiskDupe Disk Image (extension .ddi) files are floppy disk images created by the DiskDupe software from Micro System Designs. They are exact bit‐level copies of floppy disks, used to capture all sectors of a disk - including boot sector, file system, and empty space - so the image can later be duplicated or restored back to floppy disks.

DiskDupe, a tool originally for MS-DOS and Windows, creates these images when its Source is set to a floppy drive and Destination is set to a file. The image file serves as a master that can be used as a data source for writing copies to floppy disks via DiskDupe's duplication features. After creation, .ddi files can be converted to what is often called a "raw" image (.img or .raw) so they work with other emulation or disk imaging tools.

Different versions of DiskDupe store .ddi files with different header formats before the raw disk data starts. Version 5 uses a variable header that is about 1280 bytes long, including metadata whose contents change between images; version 7 uses a fixed header size of 9216 bytes that appears identical across all images inspected. The raw floppy image follows immediately after the header.

Technical identifier: the file begins with one of several DiskDupe version signatures, from which the header size is inferred (1280 bytes for version 5, 9216 for version 7), after which the image contains the entire floppy disk's worth of sector data, track by track.

How to open DDI files

Important: Different programs may use files with the DDI file extension for different purposes, so unless you are sure which format your DDI file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different DDI openers which you will find listed below.

Last updated: October 22, 2026

Various apps that use files with this extension

These apps are known to open certain types of DDI files. Remember, different programs may use DDI files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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