IBM 3270 Maintenance Manual page 379

Your screen should look like the following.
Examine your screen and verify that the
highlighted portions are solid green and the
non-highlighted portions are solid black.
DOES YOUR SCREEN MATCH THE SCREEN
ABOVE?
NO Replace the all points addressable adapter.
YES
See Section 5, "Removal/Replacement and
Adjustments."
Note: The diagnostic detects errors in all
display memory. Replace the adapter only
if the error affects your applications.
3-3200-30 Maintenance Information