Sun Microsystems SPARC classic Service Manual page 33

Note – At any point during the high-level POST, you can abort the POST process
and access the Forth Toolkit or system monitor by pressing the Stop and "a" keys
simultaneously.
NVRAM Parameters Used During POST and Boot Sequence
TABLE 2-1
NVRAM Parameter
selftest-#megs
Default = 1
diag-switch?
Default = False
auto-boot?
Default = True
If the auto-boot? parameter is set to false, the system proceeds to the Forth
Toolkit (ok prompt), or to the system monitor (> prompt). Using the Forth Toolkit,
you can direct the system to boot the operating system from a location that you
specify, or you can execute a variety of additional tests called On-Board Diagnostics.
See the Open Boot Command Reference for a complete description of the Forth Toolkit.
If the auto-boot? parameter is set to true (the default), the system boots a
standalone program. To determine which program and device to boot from, the
system checks the diag-switch? NVRAM parameter.
effect of the auto-boot? and diag-switch? parameters.
Summary of Autoboot and Diagnostic Switch Parameters
TABLE 2-2
Autoboot Switch
Parameter
False
True
True
Description
This parameter determines how many megabytes of memory
to test during high-level POST. The minimum is zero; the
maximum is the amount actually installed in the system.
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 this port. Finally, a True setting
causes the system to boot 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 process. The
system halts with either the > prompt or the ok prompt.
Diagnostic Switch
Parameter
False or True
False
True
Chapter 2
summarizes the
TABLE 2-2
1
Result
> or ok prompt
Boot operating system from
device alias "disk" or "net"
for SPARCclassic X
Boot operating system from
device alias "net"
Troubleshooting Overview 2-5