Epson 386SX - Manual (Page 206)

After checking the character fonts, respond to the prompt:
Is the display correct ? (Y/N)
If the characters match the illustration, select
Y.
If you find a
problem with the characters on the screen, select
N
to display
the error message.
Video Check
To check the video output of your monochrome adapter,
select
4.
This check displays two different screens: black and
intensified white. First you see the black screen; press any key to
display the intensified white screen. Then press any key to end
this check.
You can use this test to adjust the size of the screen display. The
vertical and horizontal adjustments are located on your
monitor.
Sync Check
This test is provided for service purposes only. If you
accidentally select this option, press any key to end the test.
Run All Above Checks
To run all the tests on the menu in sequence, select 6. When
you choose this option, all checks for the monochrome adapter
and CRT are performed automatically in sequential order.
Although you do not start each test, you must still supply the
appropriate responses to progress from one test to the next.
Press any key to return to the menu.
C-14 Performing System Diagnostics