This video describes how to connect HxC floppy drive emulator as an external (B) drive on Atari ST

Links in video:

https://hxc2001.com/ https://www.thingiverse.com/thing:2481342 https://info-coach.fr/atari/hardware/interfaces.php#Floppy_Disc_Connector

Music: Atari SAP chiptunes.