The first hard disk I met for a microcomputer was a 5meg drive for the apple ][.
It presented itself to the computer as 35 or so 143k floppies on the same controller card, so it could use the regular DOS at the time. (there might have been a patch, but I don't think so).
And, iirc, the drive was an 8" drive.
That was 1981; the following year, I had a 10meg drive assigned to me for development on an Osborne. It appeared as a single CP/M drive!
[but you could specify about 14 "users" on CP/M, and only see those--but that didn't stop you from overwriting files you couldn't see if you used the same name!]