IBM 5155 Manual To Operations page 54

POST will finish in 23 to 90 seconds, depending on the
amount of memory installed in your system. Normally,
you will receive the following responses:
A
Look in the upper left-hand comer of the screen
during POST.
~
XXX KB OK
A number appears in the upper-left comer of
your screen. The number should continue to
increase until it equals the amount of memory
installed in your system.
30-2 Start
January 1984