120 Sun Enterprise 220R Server Owner’s Guide • October 1999
About Power-On Self-Test (POST)
Diagnostics
The POST diagnostic code resides in flash PROM on the main logic board. It runs
whenever the system is turned on or when a system reset is issued. POST tests the
following system components:
■ CPU modules
■ Memory modules
■ NVRAM
■ Main logic board
POST reports its test results via LEDs located on the system keyboard and on the
system front panel. See “Error Indications” on page 138 for more information about
LEDs and error messages.
By default POST displays detailed diagnostic and error messages on a local terminal,
if one is attached to the system’s serial port A. For information about running POST,
see “How to Use POST Diagnostics” on page 121.