A ddi file extension is related to the DiskDupe a software for MS-DOS and Windows. A ddi file contains disk image.
DDI file extension - DiskDupe disk image
What is ddi file? How to open ddi files?
File type specification:
The ddi file extension is related to an old, now no longer available or supported program DiskDupe for MS-DOS and Windows operating systems.
The ddi file contains disk image created in the program.
This ddi file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.