"In the early days you couldn't swap a mouse between a Mac and an IBM PC, much less a hard drive or printer."
I mounted a 20MB external Apple hard drive:
https://retrorepairsandrefurbs.com/2023/01/25/1988-apple-20s...
... on my MSDOS system, in 1994, by attaching it to my sound card.
The Pro Audio Spectrum 16, weirdly, had a SCSI connector on it.
The SCSI would probably be meant for a CD-ROM drive. I recall my Sound Blaster Pro had a proprietary Panasonic CD-ROM interface, and at the time, soundcards often came bundled with a CD-ROM drive ( or is that vice-versa?).