IBM 3270 Hardware User's Manual page 122

11. Watch the memory test.
I
:~
KB OK
The amount of memory (shown by the xxx)
that has been checked and is working appears
in the upper corner of your screen. A cursor
will appear under the first digit of the
number. If you have not added memory, this
number is 256 for the Model 2 and 384 for
Models 4 and 6. If you have added memory,
you can check the total on the screen with
the amount of memory your wrote on the IBM
3270 Component Record card in the back of
this manual.
12. If the memory test did not run correctly make
a note of what is on the screen and the
position of the cursor.
13. Wait at least 90 seconds, and listen for one
short beep.
You may also hear the diskette drive hum and
see the "in-use" lights flicker on and off.
After a pause, you will hear a second short
beep when the diagnostic program is loaded.
Chapter 5. Locating Problems with Your PC Units 5-7