DDF File

What are DDF files and how to open them

Are you having problems opening a DDF 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 DDF files.

What is a DDF file?

DDF files have multiple uses, and Microsoft Diamond Directive is one of them. Read more about the other uses further down the page.

Microsoft Diamond Directive File

The .ddf file extension is normally found in files that are considered as Diamond Directive Files, hence the extension abbreviation. The .ddf files are text files that are commonly utilized as setting files that can be edited and modified using any text editor.

The .ddf files contain instructions and information to allow compression of files into a cabinet file which is crucial to the placement of the software in disk media.

Microsoft used .ddf files to create cabinet files that are being compressed to be part of the software that was distributed on disks. Cabinet files are used to reduce the file size and the associated download time for Web content that is found on the Internet or on corporate intranet servers.

The files are used by MakeCab.exe, a utility included with Windows.

You usually do not need to edit or view these files, as they only contain information usable by the software program that uses them.

Last updated: October 22, 2026

All known file formats using extension .DDF

While Microsoft Diamond Directive File is a popular type of DDF-file, we know of 3 different uses of the .DDF file extension. Different software may use files with the same extension for different types of data.

Ultiboard PCB Design File

These files contain PCB (Printed Circuit Board) designs created in Ultiboard by National Instruments. Ultiboard is printed circuit board design and layout software that integrates seamlessly with Multisim to accelerate PCB prototype development.

How to open DDF files

We have identified two DDF openers that are compatible with this specific type of DDF file.

Programs that open Ultiboard PCB Design files

GEM Driver Definition

GEM Driver Definition files store the configuration information that the Graphics Environment Manager (GEM) uses to describe a printer device. They are plain text files produced by GEM/3 (also known as Digital Research's GEM version 3) as part of its GDOS system. These files supply parameters that tell GEM how to load a print driver, how many dots per inch it supports horizontally and vertically, how the printer's menus should be labeled, its manufacturer and model names, and other driver-specific settings. The contents are used by GEM to drive printing hardware correctly, such as defining soft fonts, mapping device keys, setting bitmap limits, and enabling or disabling features like kerning or run-length encoding.

These files are written by printer driver vendors alongside the driver binary, and GEM reads them when it initializes a printer device. The workflow is: when a user installs or selects a printer driver under GEM/3, GEM's GDOS component loads this configuration file so that the driver's behavior matches the capabilities of the physical printer. The file includes settings such as manufacturer, model, driver load flags, printer resolution (horizontal and vertical DPI), max bitmap size, orientation, and any extensions or driver-specific formats (for example GEMEXT, DTAL, formats, etc.). GEM does not invent these values; it depends on them to match the actual hardware.

Internally a driver definition starts with a menulabel= string (at byte offset 0), followed by key-value pairs using ASCII keywords. Keywords include MANUFACTURER, DRIVERLOAD, MENULABEL, PRINTER, DEVKEY, GEMEXT, HDPI, VDPI, among others. These entries appear in simple ASCII text with values assigned by "keyword=value" lines.

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

Various apps that use files with this extension

These apps are known to open certain types of DDF files. Remember, different programs may use DDF 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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