12 SPARCstation 20 Service Manual • July 1996
OpenBoot PROM Diagnostics
On-board diagnostics are executed from the ok prompt. If there is a problem with
the operating system, the system will default to the ok prompt. The ok prompt can
also be accessed by shutting down the operating system.
TABLE 2-3 describes selected OpenBoot PROM diagnostic tests and what must occur
before each test can be executed. Some of the tests verify the proper operation of the
network controller, while other tests verify the diskette drive system, memory, and
system clock. Appendix E provides a detailed description of each test.
TABLE 2-2 Autoboot and Diagnostic Switch Settings
Autoboot Switch Diagnostic Switch Result
False Either true or false ok prompt (OpenBoot PROM commands)
True False Boot operating system from disk (default)
True True Boot operating system from network
(default)
TABLE 2-3 OpenBoot PROM Diagnostic Tests
Type of Test Description Preparation
test screen Tests the video graphics hardware and
monitor
The diag-switch? NVRAM parameter must
be set to true.
test floppy Tests the diskette drive response to
commands
Insert a formatted diskette into the drive.
test scsi Tests the system board SCSI interface
logic
The diag-switch? NVRAM parameter must
be set to true.
test net-aui Performs an internal and external
loopback test on the AUI (Thick)
Ethernet interface
A cable must be connected between the rear
panel AUI Ethernet port and the Ethernet
transceiver.
test net-tpe Performs an internal and external
loopback test on the TPE interface
A cable must be connected between the rear
panel TPE port and a TPE hub. If the tpe-
link-test? parameter is false (disabled), the
external loopback test will appear to pass even
if a cable is not connected.
test net Performs an internal and external
loopback test on the auto-selected
system Ethernet interface
A cable must be connected between the system
and the Ethernet transceiver or hub.
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