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The absolute value of the second operand is placed
in the first-operand location. The second operand
and the result are treated as 32-bit signed binary
integers.
An overflow causes a program interruption when
the fixed-point-overflow mask bit is one.
Resulting Condition Code:
o
Result is zero
1
2
Result is greater than zero
3
Overflow
Program Exceptions:
Fixed-Point Overflow
Programming Note
The operation complements negative numbers;
positive numbers and zero remain unchanged. An
overflow condition occurs when the maximum
negative number is complemented; the number
remains unchanged.
MONITOR CALL
MC
[5 I]
'AF'
o
8
16
20
31
A program interruption is caused if the appropriate
monitor-mask bit in control register 8 is one.
The monitor-mask bits are in bit positions 16-31
of control register 8, which correspond to monitor
classes 0-15, respectively.
Bit positions 12-15 in the 12 field contain a
binary number specifying one of 16 monitoring
classes. When the monitor-mask bit corresponding
to the class specified by the 12 field is one, a
monitor-event program interruption occurs. The
contents of the 12 field are stored at location 149,
with zeros stored at location 148. Bit 9 of the
program-interruption code is set to one.
The first-operand address is not used to address
data; instead, the address specified by the Bland
Dl fields forms the monitor code, whicb is placed
in the word at location 156. Address computation
follows the rules of address arithmetic; bits 0-7 are
set to zeros.
When the monitor-mask bit corresponding to the
class specified by bits 12-15 of the instruction is
zero, no interruption occurs, and the instruction is
executed as a no-operation.
Bit positions 8-11 of the instruction must
contain zeros; otherwise, a specification exception
is recognized.
Condition Code: The code remains unchanged.
Program Exceptions:
Monitor Event
Specification
Programming Notes
1. The MONITOR CALL instruction provides the
capability for passing control to a monitoring
program when selected points are reached in
the monitored program. This is accomplished
by implanting MONITOR CALL instructions at
the desired points in the monitored program.
This function may be useful in performing
various measurement functions; specifically,
tracing information can be generated indicating
which programs were executed, counting
information can be generated indicating how
often particular programs were used, and timing
information can be generated indicating how
long a particular program required for
execution.
2. The monitor masks provide a means of
disallowing all interruptions due to MONITOR
CALL or allowing monitoring for all or selected
classes.
3. The monitor code provides a means of
associating descriptive information, in addition
to the class number, with each MONITOR
CALL instruction. Without the use of a base
register, up to 4,096 distinct monitor codes can
be associated with a monitoring interruption.
With the base register designated by a nonzero
value in the B
1
field, each monitoring
interruption can be identified by a 24-bit code.
MOVE
MVI
[5 I]
o
8
16
20
31
MVC
[55]
L----'_D2_'
~
_ _ L
---I..1_B_1
--L.1_~_1
---&1_B_2
--,-I_~~
o
8
16
20
32
36
47
Chapter 7. General Instructions
7-21
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