IBM 5150 Hardware Maintenance Manual page 58

Continue running diagnostic routines. Verify the installed
devices'(refer to your Display for menu). Choose the
Monochrome Display and Printer Adapter test (4). Press
~
and
[9
and
~
(Enter), !fyou received a "401"
error message at this point, replace your IBM Monochrome
Display and Parallel Printer Adapter. Adjust your Brightness
and Contrast controls until the intensified line is brighter than
the other lines.
•
DISPLAY ATTRIBUTES
THIS LINE IS AT NORMAL INTENSITY.
THIS LINE IS INTENSIFIED.
THIS LINE IS IN REVERSE VIDEO.
THIS LINE IS BLINKING.
THIS LINE
lli
UNDERLINED.
IS THE SCREEN CORRECT? (YIN)
WERE YOU ABLE TO ADJUST FOR AN INTENSIFIED
LINE?
NO
Go to page 400-41.
YES
400-5