Parallel Port (Printer Interface) Check; Alternate Parallel Port Check - Epson Equity IIe User Manual

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 primary parallel
printer port. To perform the test, you must insert a special loop-
back connector into the parallel 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 serial port.
When you select option 9 from the Device List, you see these
prompts:
Insert the loop-back connector. Then select
check. The computer checks the port by writing and reading
data and control information, and reports errors for any pins
that are faulty. Note that if you connect a printer cable instead
of a loop-back connector, you will get errors.

Alternate Parallel Port Check

Use this option to test the operation of an additional parallel
port. To perform the test, you must insert the special loop-back
connector into the alternate parallel port so that the computer
can check individual pins of the port.
C-28 Performing System Diagnostics
to start the