DEC Digital Alpha VME 4/224, User Manual

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memtest
2. Reads each location, verifies the data, and writes the inverse of the data. The
read-verify-write is done one longword at a time. This causes the following:
• All data bits are written as a one and zero.
• All but one data bit toggle between longword writes.
• Address shorts are identified.
3. Reads and verifies each location. To verify that sections of the second and
third loops are not performed, use the -f (fast) option. This option does not
catch address shorts but does stress memory with a higher throughput. The
ECC/EDC logic is used to detect failures.
Memtest Test 2 - March Test This test uses a marching 1s/0s algorithm to test
a specified section of memory. The same range can be tested as in the graycode,
test 1. The default data patterns used by this test are 0x55555555 and its inverse
0xAAAAAAAA.
To alter the data pattern, use the -d option. In this case, the pattern entered and
its compliment are used instead of the default patterns.
Three passes are made of the memory under test.
1. Writes the data pattern entered (or default) beginning at the starting address
and marching through for the entire length specified.
2. Begins again at the starting address, reads the previously written data
pattern, and writes back its inverse. This is done a longword at a time for the
entire specified length.
3. Begins at the end of the testing region and again reads back the previously
written inverse pattern and writes back 0s. This is performed a longword at a
time, decrementing up through memory until the starting address is reached.
Memtest Test 3 - Random Test This test performs writes with random data to
random addresses using random data size, lengths, and alignments. The run time
of the random test can be noticeably longer than that of the other tests, because
the test requires two calls to the console firmware’s random number generator
every time data is written.
The random test accesses every memory location within the boundaries specified
by the -sa and -l options (as long as the length is less than 8 MB—with lengths
greater than 8 MB a modulo function is required on the seed; therefore, some
addresses might repeat and some might not test at all.
13–66 Console Commands