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o.
SECTION II.
OPERATOR'S CONTROL PANEL
If the central processor is already in the RUN mode when the external interrupt demand is set
(as a result of pressing the INTERRUPT button), the central processor enters the external
interrupt mode and the INTERRUPT button and the EXTERNAL indicator become illuminated as
soon as the four conditions outlined above are satisfied.
During processing, the external interrupt mode is terminated and the associated INTER-
RUPT and EXTERNAL indicators are reset (extinguished) when the program executes a Resume
Normal Mode (RNM) instruction.
Similarly, the external interrupt demand and the associated
indicators may be reset by pressing the INITIALIZE button.
The INITIALIZE button, however,
is not effective unless the STOP button has been pressed.
CONTROL PANEL INDICATORS
The control panel indicators are located in the lower right-hand corner of the operator's
control panel (see below).
They are visible only when illuminated.
The INTERRUPT indicator
is white, and all other indicators are red.
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PARITY Indicator
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The PARITY indicator is illuminated when incorrect parity is detected in a main memory
location or when the location addressed does not exist.
The indicator may be extinguished by
pressing either the SYSTEM CLEAR button or the INITIALIZE button prior to performing further
manual operations; however, all manual operations except BOOTSTRAP, INSTRUCT, and RUN
can be performed while the PARITY indicator is illuminated.
It should be noted that if the
BOOTSTRAP button is pressed while the PARITY indicator is illuminated, system behavior is
unspecified.
A parity check is not a normal stop condition.
However, all peripheral operations are
allowed to go to completion.
After a parity check occurs, the program normally cannot be re-
sumed.
It may be possible, however, to go back to the last instruction and attempt to rerun, but
any recovery procedure is subject to locally established policy.
2-11
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