MP/M
Operating system
MP/M is a discontinued multi-user version of the CP/M operating system, created by Digital Research developer Tom Rolander in 1979. It allowed multiple users to connect to a single computer, each using a separate terminal.
MP/M was a fairly... Wikipedia
Default user interface: Command-line interface
Initial release: 1979; 45 years ago
Latest release: 2.1 / 1982; 42 years ago
OS family: CP/M