Amiga Disk File

Amiga Disk File (ADF) is a file format used by Amiga computers and emulators to store images of disks. It has been around almost as long as the Amiga itself, although it was not initially called by any particular name. Before it was known as ADF, it was used in commercial game production, backup and disk virtualization. ADF is a track-by-track dump of the disk data as read by the Amiga operating system, and so the "format" is really fixed-width AmigaDOS data tracks appended one after another and held in a file. This file would, typically, be formatted, like the disk, in OFS.

Most ADF files are images of the Amiga-formatted tracks held on cylinder 0 to 79 of a standard 3.5" double density floppy disk, also called an 880 KB disk in Amiga terms. The size of an ADF will vary depending on how many tracks have been imaged, but in practice it is unusual to find ADF files that are not 901120 bytes in size (80 cylinders × 2 heads × 11 sectors × 512 bytes/sector).

Most Amiga programs were distributed on double density floppy disks. There are also 3.5" high density floppy disks, which hold up to 1.76 MB of data, but these are uncommon. The Amiga also had 5.25" double density disks. The WinUAE Amiga emulator supports all three disk formats, but 3.5" double density is the most common.

ADF files can be downloaded and copied to Amiga disks with the EasyADF application and various applications freely available on the Internet.

There is a program called ADF Opus, which is a Microsoft Windows–based program that allows people to create their own ADF files. This program supports creating double density (880 KB ADF files, the most common) and high density (1.76 MB) ADF files. ADF Opus also allows people to convert ADF files into ADZ files.

There is also a GPL command line program called unADF, which allows you to extract files from an ADF file.

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