Epson 10020 - Manual (Page 171)

Color Graphics Adapter and CRT Check
Use this option to check the operation of a color graphics
display adapter and monitor. This test includes several checks
that allow you to identify particular problems related to the
color display. To run this check, DIP switches 1-5 and 1-6 must
be set correctly for a color monitor.
You can select the individual checks from this menu:
COLOR GRAPHICS ADAPTER AND CRT CHECK MENU
1 - Color graphics adapter check
2 - Attribute check
3 - Character set check
4 - 40-column character set check
5 - 320x200 graphics mode check
6 - 640x200 graphics mode check
7 - Screen paging check
8 - Light pen check
9 - Color video check
10 - Sync check
11 - Run all above checks
0 - Exit
Enter selection number:
If you specified to run the color adapter check multiple times,
this menu does not appear and only the first test (Color
graphics adapter check) is performed.
If an error occurs during any of these tests, record the error code
and message, or print them out. Then contact your Customer
Care Center.
When you finish running the color adapter check, press 0 and
Enter to return to the DEVICE LIST.
D-14 Performing System Diagnostics