This is a crazy experiment that I've done using my own HW, just because I was curious to see a MP/M system running in a "real" situation with 4 concurrent terminal/users.

The FPGA board runs a VHDL Z80 Multicomp with MP/M 2.1, HD on SD and 4 serial ports (I've ported it from the Retrobrew site adding the needed modifications):

One FPGA serial port (Serial 1) is connected to the STM32 MCU inside the board, and the STM32 runs a "sketch" to act as a serial-USB bridge. So the USB connector is used to power the board and also to connect the Serial 1 port of the Multicomp (inside the FPGA) to a terminal emulator (on a PC):

Here the setup I've used:

and the video: