Technical data

4-50 Fault Isolation
4.9.7 SCSI Testing
There are two levels of SCSI testing: normal and extended. Only the normal testing can
be completed on system units with internal SCSI mass storage devices.
Normal testing is done at power-up or if the Boot ROM is in LOOPING test mode.
This test only checks the general functionality of various registers on the interface and
it only detects gross failures.
The identification line may be followed by one of these error messages:
register test failed
fuse burned out
If any of these messages appear, no attempt is made to use the interface as a boot
source. The fuse may be reset by resetting the system unit or cycling system unit
power.
Extended testing is done in a non-looping extended test mode. There are 4 sections to
this test:
1. Register test. If this test fails, the remaining sections do not test.
2. Loopback test for external devices only. It checks transmit and receive func-
tionality both with and without DMA interaction. If there is only one device
attached to the interface, the test can be performed with the device turned off
and the cable still attached. If there is more than one device, then the cable
must be detached from the device before running this test.
If this test fails, the cable test can still be executed. If the user cancels testing
at this point by typing X in response to the prompt, this section and the follow-
ing sections of the test are skipped. It takes a second or so with bit-mapped
video circuits to clear the display and shut down the IODC interface.
This test requires user interaction and provides these messages shown in
Table 4-12.