Sun Microsystems Netra t 1120, Service Manual

Page: 27 / 148

3-1
C H A P T E R
3
Power-On Self-Test
This chapter contains procedures to initiate the Netra t 1120/1125 system unit
power-on self-test (POST) diagnostics. Procedures are also included to support pre-
POST preparation, POST data interpretation and the bypassing of POST diagnostics.
3.1 POST Overview
POST can be used to determine if part of the system unit has failed and should be
replaced. POST detects approximately 95 percent of system unit faults, and is located
in the system board OpenBoot
™
PROM (OBP). The setting of two NVRAM variables,
the
diag-switch?
and
diag-level
flags, determines if POST is executed.
TABLE 3-1
lists the
diag-switch?
and
diag-level
flag settings for disabling POST
(
off
), enabling POST maximum (
max
), or enabling POST minimum (
min
).
TABLE 3-1
diag-Level
Switch Settings
Diag-Level
Setting POST Initialization Serial Port A IO
Serial Port A
Error Output
diag-Switch?
Setting
Off No N/A N/A N/A
Max Yes (power-on) Enabled Enabled True
Min Yes (power-on) Disabled Enabled True