[gzread]

The BBS software itself would have likely ran on the PCs, one instance per simultaneous user, and because it's a single-tasking OS, that means one simultaneous user per PC. They aren't just bridging packets to a single central multi-user server that serves everyone.

[icedchai]

Not necessarily. DOS multi-taskers like DESQview and TopView existed. You didn't even need a 386.

[joezydeco]

Okay, but what did you use for a multiuser backend database back then? One that could handle multiple threads reading and writing to it? A lot of these old BBS systems were just slapping together endless directories of flat text files.

[icedchai]

DOS / Desqview support filesystem locking with "share.exe." Honestly I am not sure how well this worked, but I knew guys who ran multi-line BBSes under DOS and Desqview (and later OS/2) without issue.

Even with multiple PCs you would also have similar "shared filesystem" issues. You'd need some sort of fileserver and a shared, network drive. Novell was popular at the time.

[Suppafly]

My town had a couple of guys that ran Amiga BBSs