XModem was a the new name for Modem7, which was developed by Ward Christiansen (I think I butchered his last name) ... it was also called Chistiansen Protocol.
It was the only way to transfer eight-bit/binary stuff. Some other folks came out with "Kermit" which would transfer seven bits of the byte for X number of bytes, then it would send the collection of missing eighth bits.
Ward and Randy Seuss ran a BBS in Chicago called , oddly enough, "Ward & Randy's"
All the dial-ups were straight ASCII and used the terminal codes for cursor placement (i.e., VT100, Hazeltine, Televideo ...) you had to tell the board which "terminal" you were using.
At the time, aside from BBS, you could subscribe to national services like "The Source" or Compuserve (which was absorbed by AOL much later). They offered "Timeshare" services and chat facilities, along with weather, some games ("MUDs - Multi-User Dungeons) and other features.
TCP/IP was not used, and generally unheard of outside of the DARPA crowd.
Servers used CP/M or MP/M for an operating system ... some might have used UNIX.
The "hot" terminal emulator of the day was "Crosstalk," the absolute worst was IBM's "Async Terminal Emulation" ... which is still considered by some to be the worst program/application ever released for public consumption.
Procomm and QTerm didn't come along for another couple years.
Most stuff was 300 baud only, some would support Bell 202 1200 baud (half duplex 1200). Novation and Racal-Vadic made the best modems, and everyone laughed at Hayes and their silly "AT" command set.
Ahhhh ... those were the days ....
Anyone wanna buy some buggywhips?
FWIW
Scott