I used VirtualBox to create a formatted floppy stored in the file Windows_3.1_1.img. hdiutil create -size 1440k -fs 'MS-DOS FAT12' -layout NONE -srcfolder disk2 -format UDRW -ov diskimage2.imaĪ hexadecimal/ASCII dump of the BIOS Parameter Block in the file shows the following. I executed the command from your question, which is also shown below. So, can you suggest a (scriptable, non-interactive) way to go through a folder hierarchy and convert every folder to a disk image for VirtualBox containing that folder's files? I tried to just create the images using hdiutil, but the resulting image files would not work: hdiutil create -size 1440k -fs 'MS-DOS FAT12' -layout NONE -srcfolder disk2 -format UDRW -ov diskimage2.ima None of the disks need to be bootable, so boot sector creation is irrelevant in this context. Those folders seem to have been created by just copying floppy contents on an old DOS/Win311 machine. My data files are on my APFS disk, in a folder hierarchy where every folder contains the files that were originally on the corresponding floppy.

My host system is macOS 11.6 Big Sur, and I have Homebrew tools available. For a data preservation project, I need to create a lot of those images.

VirtualBox is able to pass floppy disk images (in a format called IMA) to VMs.

Virtual floppy disk image creator