Epson EQUITY 3865X/20 PLUS - Manual (Page 66)

If the computer displays an error message while it is starting up,
run the Setup program again and check the setting the error
message indicates. If the computer still displays an error message
after you check your Setup program settings, see Appendix A or
C, or ask your dealer for assistance.
Note
Be sure to make a backup copy of your Reference diskette
after you run the Setup program and install MS-DOS. See
your MS-DOS Reference Manual for instructions on how to
copy diskettes.
Running the Setup Program
2-31