qodem (BBS-oriented terminal emulator)

qodem is a from-scratch clone implementation of the Qmodem
communications program made popular in the days when Bulletin Board
Systems ruled the night. Qodem emulates the dialing directory and
the terminal screen features of Qmodem over both modem and Internet
connections.

qodem also emulates ATASCII (Atari 8-bit) and PETSCII (Commodore
8-bit), and can be used to run a local shell.

Note: qodem-x11 doesn't handle PETSCII correctly. Instead, launch
qodem in a terminal with the PETSCII font (adjust the size= to your
taste):

$ urxvt -fn "xft:C64 Pro Mono:size=13" -e qodem

More information on BBSes can be found here, along with an up-to-date
list of telnet BBSes:
https://www.telnetbbsguide.com/