Epson 386SX - Manual (Page 30)

Using the Serial Interface
If you have a printer, a modem, or any other peripheral with a
serial interface, you can connect it to the serial (RS-232C) port
on the back of the computer.
The Equity 386SX uses a DB-9P male connector, so be sure you
have a compatible cable. To connect a serial device, follow the
same steps as above for connecting a parallel device.
Note
You need to ensure that the serial port is set up so it
functions properly. If you are using the port for a serial
printer, you need to redirect printer output to the serial
port instead of the parallel port. To do this, you can use the
MS-DOS MODE or SETMODE command or the MENU
program. See your MS-DOS Reference Manual for
instructions.
1-10 Setting Up Your System