Sun Microsystems SPARCstation 4, Service Manual

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Chapter 2 Troubleshooting Overview 2-5
Note – At any point during the high-level OBP execution, you can abort the OBP
sequence and access the FORTH Monitor by pressing the Stop and “a” keys
simultaneously.
At the FORTH Monitor prompt, you can direct the system to boot the operating
system from a location that you specify, or you can execute a variety of additional
FORTH-based tests. See the OpenBoot Command Reference for a complete description
of the FORTH Monitor.
TABLE 2-1
NVRAM Parameters Used During POST and Boot Sequence
NVRAM Parameter Description
selftest-#megs
Default =
1
This parameter determines how many megabytes of
memory to test during high-level OBP testing if
diag-
switch?
is concurrently set to
false
. The minimum is
zero; the maximum is the amount actually installed in the
system. The default is a 1-megabyte test.
diag-switch?
Default =
false
When set to
true
, this parameter forces the system to test
automatically all available memory. It also enables
diagnostic message output to serial port A. If a properly
configured terminal or “tip window” is connected,
diagnostic progress can be monitored through serial port A.
When
auto-boot?
is set to
true
and
diag-switch?
is set
to false,
diag-switch?
forces the system to boot from the
device and file specified in
boot-dev
and
boot-file
.
auto-boot?
Default =
true
If
auto-boot?
is set to
true
and
diag-switch?
is set to
true
, the system boots the operating system from the
device and file specified in the
diag-device
and
diag-
file
NVRAM parameter fields. When set to
false
, this
will suppress the boot sequence. The system halts with the
ok prompt.