Main memory diagnostics

About the main memory diagnostic menu

The tests in the main memory diagnostic menu test main memory DIMMs, analyze errors, and attempt to identify a failing DIMM component for all platforms. All but the first 12 MB of memory can be tested. The times listed for these tests are examples and might vary, depending on the platform type and amount of memory in the system. The main memory diagnostic tests can generate error messages associated with the hardware and software.

Main memory diagnostic menu

The following table describes the tests in the menu.

Test no	Test	Description
1	Comprehensive memory test (350 sec)	Runs all tests in this menu in current mode.
2	Walking data bits test (1 sec)	Verifies the data path between the CPU and memory. Runs a quick check of all data lines.
3	Walking address test (1 sec)	Verifies address paths in memory. Runs a quick test of all address lines, up to size of memory.
4	Stuck faults test (64 sec)	Scans memory to check for stuck bits, either 1 or 0.
5	Walking data words test (1 sec)	Runs a short test, walking a byte of ones through a field of 64 words of zeros. Test is repeated with complemented data.
6	Walking data bytes test (8 sec)	Runs a short test, walking a byte of ones through a field of 64 words of zeros. Test is repeated with complemented data.
7	Partial words test	Tests intermixed words, half-words, and bytes to verify ability of memory/CPU to merge data.
8	Byte patterns test (1 sec)	Spins through all 256 possible data patterns within each byte of a long word, one byte at a time.
9	RAS/CAS corners test (1 sec)	Runs a quick test between several locations that cause maximum change in the Row Address, Column Address, and RAS/CAS line.
10	Random read/write test (72 sec)	Randomly reads or writes memory locations and tests memory controller sequencing.
11	Alternating address test (48 sec)	Tests even and odd addresses, stressing PC byte marks.
12	Random data test (80 sec)	Runs a longer test, placing random data in every location. Tests DRAM cell verification.
13	Random address test (72 sec)	Runs a longer test, generating random addresses for reading and writing. Stresses DRAM addressing. Longer option also available for a test that quietly reads all memory locations.
14	MP memory test (71 sec)	Multiprocessor memory test.
15	Large memory VM test (xx sec)	A fixed pattern test that is performed and verified on platforms with memory equal to or greater than 4 GB.
42	Fill memory with data pattern	Enables you to input data pattern and memory range.
43	Check memory with data	Verifies the data pattern and memory range specified in Test 42.
44	Log2 patterns test (223 sec)	Runs a longer test of a set of log2-based (binary) data patterns.
45	Parity/ECC bits test (716 sec)	Runs a longer test to verify that each bit of a byte can propagate into the parity/ECC term.
71	Read all locations	Reads through all memory locations, looking for errors. Gives a checksum at the end. You can run this test twice to compare the checksums.
72	Dump from specified address	Enables you to set hexadecimal base addresses for the memory tests. You can repeat this test to confirm whether checksums for both tests are the same.
73	Set test address range	Enables you to set the memory range for testing. The default range is the entire testable address space.
74	Show memory size and test range	Displays memory size and test range.
91	Enable/disable looping	Enables or disables continuous running of a diagnostic test. The test is stopped when Ctrl-C is pressed or when an error is encountered if option 92 is active.
92	Stop/continue on error	Starts or stops running a diagnostic test on an error. If looping is enabled, as set by option 91, looping continues after an error is encountered.
93	Extended/normal test mode	Enables or disables extended mode on tests where extended mode is an available option.
95	Enable/disable cache	Enables or disables caching on the system.
99	Exit	Exits diagnostics.