Epson LT-286 - Manual (Page 146)

Math Coprocessor (80287) Check
Use this option to check the operation of the 80287 math
coprocessor if you have one installed in your computer. To start
the test, select option 7 from the DEVICE LIST menu.
Before running any tests, the computer checks the settings in
CMOS RAM to ensure that a coprocessor is installed. If the
coprocessor is missing, or if you have not reset the CMOS RAM
with the setup program, an error occurs and the test ends.
If the coprocessor is installed, the program runs a series of checks
on the precision with which the coprocessor performs calculations
and handles exceptions.
Parallel Port (Printer Interface) Check
Use this option to test the operation of the computer’s primary
parallel port.
To perform the test, you must insert a special loop-back connector
into the parallel port so that the computer can check the 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
serial port.
Note
If you connect a parallel printer cable instead of a loop-back
connector, you will get errors.
When you select option 9 from the DEVICE LIST menu, you see
this message:
PARALLEL PORT CHECK
Attach loop-back connector to parallel
port. Enter Y to start this check when
connector is attached, or Enter N to
return to the menu.
Performing
System Diagnostics D-21