The
Boot
ROM
will
time
out
after
approximately one
minute
and
will
then
continue into
the
boot
scanner.
This
allows
time
for
the
display
to
warm
up
and
for
the
user
to
read
the
error
messages.
These
failures
are
usually non-fatal so, in
an
Unattended
Mode,
the
Boot
ROM
will
still
boot
the
first OS
it
finds. Pressing I Return I will
terminate
the
beeping
error
code
and
abort
the
one
minute
wait. Pressing I Return I will also make
the
computer
revert
to
the
Attended
Mode.
This
means
that
the
Boot
ROM
will display all OSses found
and
will
not
boot
one until one in
chosen
and
entered
by
the
user.
General Description of Failure Codes
Table 5-3 shows
the
general meaning of
error
codes. These codes are explained
further
in
other
tables. LED
patterns
are
represented by a black
dot
for on
and
a
white
dot
for off.
Letter
designators
indicate
the
LED
in
that
position is on
or
off, depending on
the
binary
code used
to
represent
the
device
or
failure type.
Table 5-3. General Failure LED Indications
Upper 2 Bits
Fail
Indicator
LED
Code and Failure Description
State
Indication Only:
00
SS
SSSS
Where
SS
SSSS Indicates State of Power-up
Required Device Missing or
O.
DD DDDD
DTACK Failure: Where DD DDDD Indicates Device
Failing Device:
.0
DD DDDD
Where DD DDDD Indicates Device
Special Codes (Special Case Highest
••••••••
Priority Codes):
LEDs Never Accessed (or
U nnsed Code) 0
•••••
••
LEDs Failed to DTACK 0 0 0 0 0 •
O.
Timer on processor board has failed or
is
missing.
Lower 2 Bits State
or
Device Codes
LED
Code and Failure Description
Miscellaneous (Highest Priority):
XX
00
FFFF
Where
FFFF
indicates Failure (Xs are don't-care bits)
Internal Peripheral Failure (Medium
XX
O.
PPPP
Priority): Where
PPPP
is
Peripheral Number
I/O
Card Failure (Lowest Priority):
XX.
S SSSS
Where S SSSS
is
Select Code
State and Failure Codes
Table 5-4a is a list
of
all LED failure codes used in
the
computer
Boot
ROMs. Codes
are
listed
here in numerical
order
for easy reference,
and
then
again in
order
of occurrence
and
priority.
162
Troubleshooting
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