To setup a USB to serial converter to use with DOSBox on Linux:

1. Find the device ID for USB to serial adapter. It’s probably like “/dev/ttyUSB0”

   ls /dev/ttyUSB*
   

2. Allow non-sudo serial port access by adding the username to “plugdev” and “dialout” groups:

   adduser $(whoami) plugdev dialout
   

3. Logout and login.

4. Edit ~/.dosbox/dosbox*.conf, under [serial] modify the serial1=dummy:

   serial1=directserial realport:ttyUSB0
   

DOSBox should work with serial device on COM1

Notes

DOSbox config manual

If you can’t access a device, ensure the username is in “plugdev” group as noted above, and perhaps try (assuming device is /dev/ttyUSB0):

chmod 666 /dev/ttyUSB0