HP 98780 CE Handbook page 16

5-2
98780 Diagnostics
F Focus Alignment Pattern
Press F; "%" characters appear on the display. Check the characters to ensure they are clear
and readable. If necessary, remove the top covers and adjust the focus control to achieve the
best overall character focus (refer to Chapter 4 for adjustment procedures). It may not be
possible to achieve perfect focus in all areas of the display.
L Linearity
Press L; various"
+ "
characters appear in a pattern. This test is used to check linearity at the
factory. It is not intended for field use.
B Full Line Buffer
Press B; the CRT displays:
This test checks the 80-character line buffers on the A34 assembly (left leg)'plus the ability to display
information.
K Soft Keys
Press K then press each soft key on the lower CRT bezel. A display appears above the key
when it is pressed to indicate the operation of the key.