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applies to the second or third halfword of the
instruction, it is unpredictable whether the
instruction-fetching event is indicated.
2. When the operation is completed, the event is
indicated regardless of whether any program
exception or the monitoring event is
recognized.
3. Successful branching, storage alteration, and
general-register alteration are not indicated for
an operation or, in case the instruction is
interruptible, for a unit of operation that is
suppressed or nullified.
4. When the execution of the instruction is
terminated, general-register or storage
alteration is indicated whenever the event has
occurred, and a model may indicate the event if
the event would have occurred had the
execution of the instruction been completed,
even if altering the contents of the result field
is contingent on operand values.
5. When LOAD PSW or SUPERVISOR CALL
causes a PER condition and at the same time
introduces a new PSW with the type of
PSW-format error that is recognized
immediately after the PSW becomes active, the
interruption code identifies both the PER
condition and the specification exception.
When these instructions introduce a
PSW-format error of the type that is recognized
as part of the execution of the following
instruction, the PSW is stored as the old PSW
without the specification exception being
recognized.
The indication of PER events concurrently with
other program interruption conditions is
summarized in the figure "Indication of PER
Events. "
Chapter 4. Control
4-13
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