Epson 10020 - Manual (Page 184)

Before running any tests, the computer checks
DIP switch 1-Z
on the front panel to ensure that a coprocessor is installed. If
the coprocessor is missing, or if you have not set
DIP switch 1-2
correctly,
an error occurs and the test ends.
The program then runs a series of checks to test the precision
with which the coprocessor performs calculations and to detect
whether it correctly handles exceptions. The program reports
any errors that occur.
Parallel Port (Printer Interface) Check
Use this option to test the operation of the secondary parallel
printer port. For example, you would select this option to test
the built-in port if you have assigned it as the secondary port, or
if you have installed an option card that provides a 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 Customer Care
Center if you need a loop-back connector (or see Appendix B
for signal/pin assignments to make your own loop-back
connector). Note that a different connector is required co test
the serial port.
When you select option 9 from the DEVICE LIST, you see
these prompts:
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.
Insert the loop-back connector. Then press Y and Enter to
start the check.
Performing System Diagnostics
D-27