Compaq AlphaServer ES45 Service Manual page 159

The output of the show error command is based on information logged to the
serial control bus EEPROMs on the system FRUs. Both the operating system
and the ROM-based diagnostics log errors to the EEPROMs. This functionality
allows you to generate an error log from the console environment. No errors are
displayed for fans or the OCP because these components do not have an
EEPROM.
Syntax
show error
All FRUs with errors are displayed. If no errors are logged, nothing is displayed
and you are returned to the SRM console prompt.
Example 4–24 shows TDD, SDD, checksum, and sys_serial_num mismatch
errors logged to the EEPROM on the system motherboard (SMB0). Table 4–2
shows a reference to these errors. The bit masks correspond to the bit masks
that would be displayed in the E field of the show fru command.
FRU to which errors are logged; in this example the system motherboard,
SMB0.
A TDD error has been logged. TDDs (test-directed diagnostics) test specific
functions sequentially. Typically, nothing else is running during the test.
TDDs are performed in SROM or XSROM or early in the console power-up
flow.
An SDD error has been logged. SDDs (symptom-directed diagnostics) are
generic diagnostic exercisers that try to cause random behavior and look
for failures or "symptoms." All SDDs are logged by Compaq Analyze.
Three checksum errors have been logged.
There was a mismatch between the serial number on the system
motherboard and the system serial number. This could occur if a
motherboard from a system with a different serial number was swapped
into this system.
SRM Console Diagnostics 4-57