To specify which .ide file to use click the 'IDE' button (yellow ellipse) or type in a specific ide filename (orange ellipse). Default 'elf2k.ide' is used but this can be changed to any file name. Number of tracks, heads and sectors can be specified via the Device Port button, default is 512 tracks, 4 heads and 26 sectors. ElfOs can be installed on the ide disk file, see also Installation Elf/Os 2.8 or Installation Elf/Os 3.0. The eject button (purple ellipse) will empty the ide filename field (orange ellipse).
After initial start-up the file elf2k-installation.ide is made available including a pre installed Elf/Os and additional Elf/Os software. The installation file will be renamed to elf2k.ide if that file doesn't exist.