Technical data

4-54 Fault Isolation
Extended Self-Tests
When you select Extended, the self-test starts over and the long memory test will be
run. It takes about 4 seconds per megabyte (as opposed to the standard, or default,
memory test, which takes about 1 second per megabyte).
This mode also invokes extended testing by executing external loopback and cable test-
ing on the LAN and the external SCSI interfaces. Extended SCSI self-tests cannot be
performed on internal SCSI mass storage devices. A prompt asks you to turn OFF any
SCSI peripherals.
Extended Test Mode can be used while running in continuous mode. The result is con
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tinuous extended testing. SCSI extended testing cannot be done in this combination.
With the ThinLAN interface, all extended test functions do work. If an external Media
Attachment Unit is not connected for AUI interfaces, the extended test reports a fail-
ure.
Test Memory
Memory tests are enabled as a default mode. If you do not want to run memory tests,
type the command A, then select the No option from the prompt.
Memory tests are performed on main memory. Both read/write and parity tests are run.
You see error messages displayed if memory fails. Memory error messages are inter
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preted differently for each type of memory test.
For word-wide memory error messages, the following messages appear at the bottom
of your display in this format:
Memory Failed at (address)
(W:BBCCDDEE, R:BBCCDDEF)
In the above message, the hex address had the hex data BBCCDDEE written (W) into
and read (R) out of the address. If the read data is different than the write data as
shown in the above example in the least significant hex digits, that indicates an error.
Parity error messages are of two types:
PARITY BIT ERROR AT (address)
means a failure was detected in the parity checking RAM for the address shown.
DATA PARITY ERROR AT (address)
means a RAM failure was detected at the indicated address. The address in parity er-
ror messages is the lowest of four consecutive addresses. Errors could have occurred