IBM 3270 Maintenance Manual page 176

If the first character of the error code is
4
or 5,
the failure is on the 128KB Memory-Printer
Adapter.
ENTER THE NUMBER(S) OF OPTIONS TO TEST
OR PRESS ENTER TO SELECT ALL OPTIONS
72
TESTING - XXXKB MEMORY
THIS TEST TAKES UP TO TWO MINUTES
PLEASE STAND BY
+
XX:XX:XX
ERROR - XXXKB MEMORY 201 S
FAILING ADDRESS - SPACE/MODULE XXXXX XX
PRESS ENTER TO CONTINUE
IS THE FIRST CHARACTER OF YOUR
ERROR CODE A 4 or 51
YES Replace the 128KB Memory-Printer
Adapter and rerun the diagnostics (see
page 3-200-55).
NO
October 1984 3-200-51