hard_drive_0

The option documentation is properly formatted yet

Example: path/to/image.hdf

A hard disk image file (.hdf) can be mounted within fs-uae with options hard_drive_0 through hard_drive_9. Currently, only default "geometry" is supported. (surfaces: 1, reserved: 2, sectors: 32 and block_size: 512)

hard_drive_0 = path/to/image.hdf

Instead of using hard disk image files, you can also mount folders as drives. This is enabled by pointing the hard_drive_x options at a folder on you computer:

hard_drive_0 = path/to/folder

You can also mount a zipped folder as a drive. It will be mounted read-only, but otherwise works as a normal folder mount:

hard_drive_0 = path/to/folder.zip

See also [hard_drive_0_controller], [hard_drive_0_file_system], [hard_drive_0_label], [hard_drive_0_read_only], [hard_drive_0_type].

Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/hard_drive_0