How It Fits Together
This section describes how the various diagnostic tools work together in the different
power-on modes. This description assumes you are using a graphics monitor to view
test results. The flowchart in Figure 2–1 outlines the roles played by various
diagnostics during the default boot mode.
POST runs automatically at power on, if the Stop(L1)-d keys are pressed and held
down after the power-on, or if thediag-switch? parameter is set true.
While the low-level POST code executes, the CAPS lock LED on the keyboard flashes
to indicate that testing is in progress. If a failure occurs in POST, the failing
replaceable unit is encoded on three LEDs located on the Type-5 keyboard. See
“Power-On Self Test (POST)” on page 13 later in this chapter for more information.
If POST passes, the system probes for SBus devices and interprets their drivers. Next,
high level tests are performed. The word Testing displays while the high level
tests are running. After Testing is displayed, if you want to enter the Forth Toolkit,
(indicated by the ok prompt), press the Stop(L1)-a keys simultaneously.
When the autoboot switch parameter is set to false (not the default), the ok prompt
appears. Table 2–1 gives the results of various combinations of the autoboot an
diagnostic switch settings. The ok prompt is the default prompt. To change to the
Monitor prompt (>) see the Open Boot 2.0 Command Reference.
If the autoboot switch parameter is set to true (default), and the diagnostic switch
parameter is set to false (default), SunOS is booted using the device alias “disk.” If
the autoboot switch parameter is set to true (default), and the diagnostic switch
parameter is set to true (not the default), SunOS is booted using the device alias “net.”
TABLE 2–1 Autoboot and Diagnostic Switch Parameters
Autoboot Switch
Parameter
Diagnostic Switch
Parameter Results
False (Don’t care)
ok prompt (Forth Toolkit)
True False Boot SunOS (vmunix) from disk
True True Boot SunOS (vmunix) from network
To boot user-specified programs, such as the SunDiagnostic Executive, you must be
at the ok prompt. See “On-Board Diagnostics” on page 14 later in this chapter for a
detailed procedure on how to obtain the ok prompt.
Diagnostics Overview 11
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