How It Fits Together - Sun Microsystems SPARCstation 2 Service Manual

2

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.
When you turn on system power, the low-level POST code, stored in the boot
PROM, is executed. While low-level POST code is executing, you will see the
four LEDs on the keyboard flashing to indicate that testing is in progress. If a
failure occurs in POST, the failing field replaceable unit (FRU) is encoded on
the four LEDs located on the Type-4 keyboard. See "Power-On Self-Test" later
in this chapter for more information.
If the POST passes, the system probes for SBus devices and interprets their
drivers. Next, high level tests are performed. You will see the word Testing
while the high level tests are running. After Testing is displayed, if you
want to enter the Monitor, (indicated by the > prompt), press the L1-A keys
simultaneously.
If the autoboot switch parameter is set to false (not the default), you will obtain
either the > or ok prompt. The > prompt is the default prompt. You can
change the default prompt to obtain the ok prompt, the Forth Toolkit prompt,
as the default. To make the ok prompt the default prompt, see the Open Boot
PROM 2.0 Toolkit User's Guide.
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
path /sbus/esp/sd@3,0. 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 path /sbus/le.
To boot user-specified programs, such as the SunDiagnostic Executive, you
must be at the > or ok prompt. See "On-Board Diagnostics" later in this
chapter for a detailed procedure on how to obtain the > and ok prompts.
Diagnostics Overview 21