Power-On Self-Test (Post) - Sun Microsystems SPARCstation 5 Service Manual

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CHAPTER

Power-On Self-Test (POST)

This chapter describes the Power-On Self-Test (POST) for Normal, Full, and
Abbreviated modes, available with your SPARCstation 5 system.
The Power-On Self-Test (POST) diagnostics reside in the OpenBoot PROM located on
the system board. There are two POST modes: Normal and Diagnostic.
Power-On Self-Test (POST)
The Power-On Self-Test (POST) runs when you turn on the system unit power switch
and any of the following conditions apply:
4 diag-switch? NVRAM parameter is set to true.
4 Stop-d keys are held down when you turn on the power.
4 Keyboard is disconnected, and diag-switch? is set to false.
The POST comprises a sequence of tests designed to evaluate the major hardware
components of the main logic board in the short time before the OpenBoot PROM
firmware takes control. The POST does not perform extensive testing on any
component of the main logic board. Only major failures can be detected by the POST.
Four different LEDs on the keyboards are used to indicate the progress and results of
the POST. These LEDs are on the Caps Lock, Compose, Scroll Lock, and Num Lock
keys, as shown in Figure 3–1, Figure 3–2, and Figure 3–3. To indicate the beginning
of the POSTs, the four LEDs briefly light all at once. The monitor screen remains
blank, and the Caps Lock LED blinks for the duration of the POST.
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