Service Aids; Error Indicators; Ce Switches; Jumpers - IBM 5110 Maintenance Information Manual

Service Aids
ERROR INDICATORS
There are two error indicators on the 511 O-the control
panel PROCESS CHECK light and messages on the display.
The PROCESS CHECK light is activated by parity errors
detected in any of several functional units. (See Control
Unit
in Section 3.) When the PROCESS CHECK light is
activated, the machine stops immediately with the error
latched. This allows you to identify the type of error by
means of the logic probe.
Error messages are displayed only when enough of the 5110
internal functions are operating to ensure that the display
message is accurate. Error messages appear whenever the
customer programs sense an error condition or when the
CE diagnostic programs are run and an error occurs. The
errors that occur when the diagnostic programs run are
coded to provide entry points to the MAPs.
Halt codes are displayed when a failure occurs during the
bring up program. When the bring up program is run, a
sequence of letters (A through
Q)
is displayed; each letter
indicates the completion of a portio,,! of the bring up pro·
gram. If a failure occurs during bring up, the last letter of
the sequence indicates the failure that occurred. This
information is used in the MAPs to determine the cause of
the failure.
CE Switches
Two CE switches, run and step, are located inside the
5110 next to the display assembly. Removing the top cover
allows access to these switches. The run switch is the two·
position toggle switch and the step switch is the small
momentary switch.
Run Switch
The run switch controls the operational state of the 5110.
To execute programs, the run switch must be in the RUN
position. This is the processing state and the switch must
be in this position when the 5110 is returned to the
customer.
Moving the switch from the RUN position stops program
processing upon completion of the E cycles of the current
microinstruction.
4·64
To see the effect of the run switch when the 5110 is
processing, set the DISPLAY REGISTERS switch to the
DISPLAY REGISTERS position. Register 0 of one of the
program levels changes rapidly unless the 5110 is halted by
a halt microinstruction. Moving the run switch from the
RUN position stops register 0 and allows you to read the
hex numbers on th.e display. The 5110 remains stopped
until the run switch is returned to the RUN position or
until the step switch is pressed.
Step Switch
The step switch has no effect on the operation of the 5110
unless the run switch is moved from the RUN position.
When the step switch is pressed, the 5110 executes one
microinstruction and then stops. The step switch must be
pressed and then released in order to execute each micro·
instruction. Pressing the step switch moves the number in
register 0 of the current program level to the next micro-
instruction address as each microinstruction is processed.
JUMPERS
Machine Check Jumper
This jumper connects pin J2-S07 to J2-S09 on the 5110
A 1 board. Removing this jumper allows the controller to
continue functioning When an error occurs on the
machine check line. Misleading results can be received
by running with the jumper removed.
Basic Language Jumper
This jumper connects pin H2-S04 to H2-U08 on the AI
board. The jumper ties the '+APL switch' line to ground.
Katakana Check Jumper
This jumper connects pin H2-S12 to G2-P13 on the Al
board. This jumper is used with the Katakana display card
to instruct the microcode to handle the country select
keycode properly.
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