Powering the System On and Off
Power for the I/O subsystems is controlled by the attached processor subsystem and
the System Power Control Network (SPCN).
Power-On Self-Test
After power is turned on and before the operating system is loaded, the system does a
power-on self-test (POST). The RIO loop that connects the I/O subsystems to the
system unit is tested. Tests are also performed on the installed adapters and devices in
the I/O subsystems. If an error occurs during the POST, an error code is displayed on
the system operator panel LCD that indicates which part is failing and which subsystem
contains the error.
36 Eserver pSeries 7311 Model D10 and Model D20 Service Guide