Epson 386/25 - Manual (Page 280)

Starting System Diagnostics
To run the System diagnostics program, you must turn on or
reset your computer with the Reference diskette in drive A. If
you start this program in any other way, some tests may produce
strange results.
To start the System diagnostics program, follow these steps:
1. Insert the Reference diskette in drive A.
2. Turn on or reset the computer. The Operation Menu
appears.
3. If the Num Lock indicator is illuminated, press Num Lock
to turn off the function.
4. Press 3 or use 1 to select System diagnostics and
then press Enter.
When you start the System diagnostics program, the computer
checks any peripheral devices that are connected to the system.
Then you see a list of the devices available for testing. This list
includes only the devices that are part of your system, such as
: following, for example:
E-2 Performing System Diagnostics