Epson 20 - Manual (Page 158)

I s t h e d i s p l a y c o r r e c t ( Y / N ) ?
After checking the character fonts, respond to the prompt:
Is the display correct (Y/N)?
If the characters match the illustration, press Y and then Enter. If
you find a problem with the characters on the screen, press N and
Enter to display the error message.
40-column Character Set Check
To check your 40-column character set, press 4 and then Enter. The
character fonts that are included in the internal character generator
display on your screen. Compare the characters on your screen to the
following illustration.
C-14 Performing System Diagnostics