Epson 386SX - Manual (Page 221)

Parallel Port (on Video Adapter) Check
Use this option to test the operation of an additional parallel
port on a video adapter. To perform the test, you must insert the
special loop-back connector into the parallel port on the video
adapter so that the computer can check individual pins of the
port.
This test is similar to the Parallel Port Check. For more details,
see the description of the Parallel Port (Printer Interface)
Check.
Serial Port (RS-232C Port) Check
Use this option to test the functions of the primary serial
communications (RS-232C) port. To perform the test, you must
insert a special loop-back connector into the RS-232C port so
that the computer can check individual pins of the port.
Contact your dealer if you need a loop-back connector. Note
that a different connector is required to test the parallel port.
When you select option
11
from the Device List, you see these
prompts:
Attach loop-back connector to serial
port before starting the check.
Start the check ? (Y/N)
Insert the loop-back connector. Then select
Y
to start the
check.
Performing System Diagnostics C-29