System Troubleshooting and Diagnostics
5.3 Interpreting Power-On Self-Test and ROM-Based Diagnostic Failures
testing. It is easier, however, to input the memory module numbers 1–4.
For example, if test 4F fails, test the second memory module as follows:
>>>T 4F 2 2
You should run this test for each memory module; if a failure is detected on
MS690 number 2, for example, and there are four memory modules in the
system, continue testing the rest of the modules to isolate the FRU using
the process of elimination.
You can also specify the address increment. For example, to test the third
memory module on each page boundary, type:
>>>T 4F 3 3 200
By default, the memory tests increment by 1 Mbyte, testing one longword
in each 1 Mbyte block. If an error is detected, the tests start testing on
a page boundary. Test 48 (address shorts test) is an exception: it checks
every location in memory since it can do so in a reasonable amount of
time. Other tests, such as 4F (floating ones and zeros test), can take up
to one hour, depending on the amount of memory, if each location were to
be tested. If you do specify an address increment, do not input less than
200 (testing on a page boundary), since almost all hard memory failures
span at least one page. For normal servicing, do not specify the address
increment, since it adds unnecessary repair time; most memory subsystem
failures can be found using the default parameter.
All memory tests, except for 40, save the MMCDSR, MESR, MEAR in
parameters 7, 8, and 9, respectively.
3. T 9C
The utility 9C is useful if test 31 or some other memory test failed because
memory was not configured correctly. Refer to Section 4.4 to see an
example of the test 9C output.
To help in isolating an FRU, examine registers MEMCON 0–7 by entering
T 9C at the console I/O mode prompt.
4. T 40
Although the SHOW MEMORY/FULL command displays pages that are
marked bad by the memory test and is easier to interpret than test 40,
there is one instance in which test 40 reports information that SHOW
MEMORY/FULL does not report. You can use test 40 as an alternative
to running script A9 to detect soft memory errors. Specify the third
parameter in test 40 (see Table 5–9) to be the threshold for soft errors. To
allow zero errors, enter the following:
System Troubleshooting and Diagnostics 5–61
