The segment-translation exception is
indicated by a program-interruption code
of0010 hex (or 0090 hex if a concurrent PER event is indicated).
Significance Exception
A significance exception is
when the result fraction in
point addition or subtraction
recognized
floatingis zero. The interruption may be disallowed by
the significance mask(PSW bit 23 in the EC mode and PSW bit 39 in the BC mode).
The operationis completed. The signif
icance mask also affects the result ofthe operation. When the mask bit is
zero, the operation is completed by
replacingthe result with a true zero. When the mask bit is one, the operation
is completed without further change tothe characteristic of the result.
The instruction-length codeis 1 or 2. The significance exception is indicated
by a program-interruption code ofXXOE hex (or XX8E hex if a concurrent PER event is indicated), where XX is the
exception-extension code.
Space-SwitchEvent A space-switch event is recognized at
the completion ofa PROGRAM CALL with
space switching(PC-ss) or a PROGRAM TRANSFER with space switching (PT-ss) when any of the following is true:
1.The space-switch-event-control bit,
bit 31 of controlregister 1, is one before the operation.
2.The space-switch-event-control bit
is one after the operation.
3. APER event is reported.
The oldPASN, which is in the right half of control register 4 before the
execution of the instructionPC-ss or PT-ss, is stored at real locations
146-147. The old space-switch-event
control bit isplaced in bit position 0 and zeros are placed in bit positions
1-15 at real locations 144-145.
Theoperation is completed. The instruction-length code is 2. I The space-switch event is indicated by a I program-interruption code of OOIC hex I (or 009C hex if a concurrent PER event is indicated). Programming Notes
1. The space-switchevent permits the
control program to galn control
whenever a program enters or leaves
a particular address space. The
space-switch-event-control bit isloaded into control register 1,
along with the remaining bits of
the primary segment-table desig
nation, whenever control register 1
is loaded.
2. The space-switch event maybe useful in obtaining programmed
author;zat;onchecking, in caus;ng
additional trace information to be
recorded, or in enabling or disabl
ing theCPU for PER or tracing.
3. Bit 95 of the ASN-second-table
entry (ASTE) is loaded into bit
position 31 of control register 1as part of the PC-ss and PT-ss operations. If bit 95 of the ASTE
for a particular address space is
set to one, then a space-switch
event is recognized when a program
enters orleaves the address space
bymeans of either a PC-ss or a PT-ss. 4. The occurrence of a space-switch
event at the completion of aPC-ss or PT-ss when any PER event is
indicatedpermits the control
program to determinethe address
space from whichthe instruction
causingthe PER event was fetched. Special-Operation Exception
A special-operation exception is recognized when any of the following is true:
1. Execution ofSET SYSTEM MASK is attempted in the supervisor state
andthe SSM-suppression control,
bit 1 of control register0, is
one.
2. Execution of any ofthe following
instructions is attempted withOAT off: EXTRACT PRIMARY ASN EXTRACT SECONDARY ASN INSERT ADDRESS SPACE CONTROL INSERT VIRTUAL STORAGE KEY MOVE TO PRIMARY MOVE TO SECONDARY SET ADDRESS SPACE CONTROL SET SECONDARY ASH 3. Execution of PROGRAM CALL or PROGRAM TRANSFER is attempted, and Chapter 6. Interruptions 6-25
indicated by a program-interruption code
of
Significance Exception
A significance exception is
when the result fraction in
point addition or subtraction
recognized
floating
the significance mask
The operation
icance mask also affects the result of
zero, the operation is completed by
replacing
is completed without further change to
The instruction-length code
by a program-interruption code of
exception-extension code.
Space-Switch
the completion of
space switching
1.
bit 31 of control
2.
is one after the operation.
3. A
The old
execution of the instruction
146-147. The old space-switch-event
control bit is
1-15 at real locations 144-145.
The
1. The space-switch
control program to galn control
whenever a program enters or leaves
a particular address space. The
space-switch-event-control bit is
along with the remaining bits of
the primary segment-table desig
nation, whenever control register 1
is loaded.
2. The space-switch event may
author;zat;on
additional trace information to be
recorded, or in enabling or disabl
ing the
3. Bit 95 of the ASN-second-table
entry (ASTE) is loaded into bit
position 31 of control register 1
for a particular address space is
set to one, then a space-switch
event is recognized when a program
enters or
by
event at the completion of a
indicated
program to determine
space from which
causing
A special-operation exception is recog
1. Execution of
and
bit 1 of control register
one.
2. Execution of any of
instructions is attempted with