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Corrective Maintenance
Prime Proprietary
5.
If the
system
(PRIMOS)
stays
up
for
one
minute
after
Warm
Starting,
the
memory
parity
error
is
recorded
in
LOGREC.
Otherwise, a SHUTDN ALL has to be done in order to get
the
error
recorded.
6.
Using the information from LOGREC or the
registers
(recorded
in
step
2),
isolate
the
bad
memory
chip
as
outlined under the
Troubleshooting with LOGREC subsection in this chapter.
6.2.4.4 Machine Check Handling ©
Machine checks occur when the CPU detects bad parity
on
one
of
its
internal data paths or one of the external buses (BPD, BPA, BMA or BMD
out).
Machine checks can be caused by the CPU, controllers or memory.
Machine
checks during PRIMOS operation are detectable by system halts
at location 4/305 (segment 4, location 305
octal).
On
PRIMOS,
the
first
halt
after a Cold Start causes the entire register file set to
be saved in memory.
This save is not disturbed until
the
next
Cold
Start.
Reference
the
memory maps for revision of PRIMOS being run,
for the location of these saved registers, if they are needed.
Upon detecting the machine check halt, the CPU reports the
status
of
the
check
in
its
diagnostic
status
word (DSWSTAT) located in the
register files at location "abs" (absolute), 5
octal,
high
and
low
side.
Use
the
following
steps
to isolate the cause for a machine
check.
NOTE
Never use the MASTER CLEAR
button
or
the
SYSCLR
and
VIRY
'commands
before
recording
the
halt
location in the system
logbook and
determining
all
the
recovery
actions
to
be
performed.
Some recovery actions are ineffective unless they
are taken before using MASTER CLEAR, SYSCLR or VIRY.
1.
Note the DSWSTAT that appears on the system console.
2.
Use the information obtained from diagnostic status word high side
(DSWSTATH) and Table 6-12 to aid in isolation of the bad component
of the system.
3.
A Warm Start is
not
recommended
after
a
Machine
Check
halt.
However,
in
order
to
get the halt recorded in LOGREC, you must
Warm Start and keep up the system for one minute or
do
a
SRUTDN
ALL.
It is recommended that no user activity be reinitiated after
a Machine Check, until a Cold Start is possible.
070-C
6-
16.
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