Sun Microsystems 1.0, Service Manual

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Boot PROM Diagnostics
The diagnostics stored in the boot PROM include the following:
4
Power-On Self-Test
4
On-Board Diagnostics
If there is system trouble, you may want to run extended on-board diagnostics to take
advantage of thorough tests including — but not limited to — Ethernet, memory,
and diskette drive tests. Table 2–3 shows the keyboard LED diagnostic codes.
The following sections describe the boot PROM diagnostics.
Power-On Self Test (POST)
The Power-On Self-Test (POST) runs when you turn on the system power switch and
one of the following conditions apply:
4
Press
Stop(L1)-d
keys
4
The
diag-switch?
NVRAM parameter is set true
4
The system keyboard is disconnected
Note - When the keyboard is disconnected, POST is not verbose.
The POST code, which resides in the boot PROM, is executed by the CPU (IU) when
the Pok signal is received from the power supply. The POST consists of a sequence of
tests designed to test the major hardware components of the MLB in the short time
before SunOS is booted. POST does not perform extensive testing on any component
of the MLB. Only major failures can be detected by POST.
If a failure occurs in POST, a specific LED pattern is displayed. The LEDs are on the
Compose, Scroll Lock, and Num Lock keys. See Figure 2–2. The Caps Lock key LED,
located just above the left-hand Shift key, is not used as a power-on test failure
indicator, but flashes on and off while POST is running. During normal system
operation, the LEDs should not be interpreted as diagnostic error indicators.
SunOS is booted automatically following the system successful initialization, unless
the NVRAM configuration options specify otherwise.
Diagnostics Overview
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