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System Verification and Troubleshooting
3-14. Stack Register Loading
Because of the queue-down function
which
occurs
when
the
CPU
halts,
stack
registers must be loaded at their location in mem-
ory.
For test purposes it is possible to load the
stack
regis-
ters
which
are
on
the S-Bus PCA and R-Bus PCA.
However, when
queue-up takes place after the CPU is started, the register
con-
tents will be destroyed.
3-15. CPU Register Displays
When CPU registers are displayed, the register contents
are
ac-
quired
either from the computer S-Bus or R-Bus.
A switch on the
Maintenance Panel permits display from either the
S-Bus
or
the
R-Bus.
This switch is titled SINGLE CYCLE REGISTER DISPLAY, ALT/
NORMAL (panel row 11) •
3-16. General-Use Display
When the REGISTER SELECTION TEST lamp is lighted,
any 16 bits or
16
binary signals
can be applied for display
to jack J3 of the
MPI PCA (figure 3-4).
The bits or signals must have TTL
silicon
logic levels.
They are displayed in the REGISTER DISPLAY
(0:15)
lamps on the Maintenance Panel.
The pins in J3 to which connec-
tion is
made are listed in table 3-3.
The table also shows two
trigger pulses and
a
+5 volt source.
These are supplied
by the
MPI PCA.
The MR signal is an input to the PCA
that is used for
factory
test purposes.
For any particular
application of
the
general-use
display,
a cardboard
overlay
can be made
for the
REGISTER DISPLAY
lamps with appropriate signal
names marked
on
the overlay.
(A ticket punch is a suitable device for making the
holes in the cardboard.)
3-17. Maintenance Panel Test
The following tests check the operability of most circuits in the
Maintenance Panel.
Most circuits in the MPI PCA are not checked.
If performed
as described,
and if step a
in paragrah
3-18 has
previously been completed,
the test can be
executed without in-
terfering with
normal computer functioning.
(Switch information
from
the Maintenance
Panel does not
enter the
computer system
when switch Sl on the MPI PCA is at the SWITCH TEST position.)
3-18. LAMP TEST. Perform the lamp test as follows:
a.
Connect the
Maintenance Panel to the computer system
in the
normal manner (figure 3-4). Before making connections be sure
+5 vol ts has been removed from the system and ensure that all
bistable switches on the Maintenance Panel are down.
3-26
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Troubleshooting
