For the Amiga, if you are going to donwload abandonware, most sites will use the .ADF format (generally zipped), from which you can easily generate floppy disks using greaseweazle.
However, if you need to archive your own disks and those have copy protections in place, you may need to use one of “RAW tracks” formats below, for example .SCP (which abandonware sites also use for copy protected games.)
Basic formats (Data Only)
.ADF
- Simple, uncompressed format
- Widely used by emulators
- ADF files contain a byte-for-byte copy of the sectors and tracks from an Amiga floppy disk. For standard Amiga disks, which are 3.5" 880 KB double-density disks, an ADF file typically contains 1760 sectors (11 sectors per track, 80 tracks, and 2 sides).
- It represents data in a raw, uncompressed format, mimicking how the data would appear on an actual disk.
- Supported by #greaseweazle
.ADZ
- Compressed version of .ADF but not as widely supported
Advanced formats (with MetaData)
.DMS (the Disk Masher System)
- Proprietary disk Archiving system developed on the Amiga before emulators were a thing.
.IPF (Interchangeable Preservation Format)
- Universal ‘Golden Image’ Format
- Includes disk structure
- Supported by #greaseweazle (for writing to disk only)
RAW tracks formats
.HFE
- Stores Raw Bitcells, 1 revolution per track
- Supported by #greaseweazle
- No automatic verification is performed
.SCP (SuperCard Pro flux data)
- Stores Raw Flux, multiple revolutions per track
- Supported by #greaseweazle
- No automatic verification is performed (different revolutions may contain different read data)
.RAW (Kryoflux)
- 1 file per track and per side with names like
name<track>.<side>.raw - Stores Raw Flux, multiple revolutions per track
- Supported by #greaseweazle
- No automatic verification is performed (different revolutions may contain different read data)