Page of GA22-7000-4
Revised September 1, 1975
By TNL: GN22-0498 Implicit Explicit Translation
Translation (Operand of LRA) Indication Condition Control register contents
1 Invalid page size (CR 0 bits 8 and 9) One in bit position 10 of control register 0 segment size (CRO bits 11 and 12) Segment table entry Segment table length violation
Entry protected against fetching or storing Invalid address of entry I bit on One in an unassigned bit position
2
Page table entry
Page table length violation
Entry protected for fetching or storing Invalid address of entry I bit on One in an unassigned bit position
2
Access for instruction or data
Location protected Invalid address
Explanation: TS Translation-specification exception. Instruction TS TS TS ST A ST TS PT
A
PT TS P
A
* Operand Action Indication Action
suppress TS suppress
suppress TS suppress
** suppress TS suppress ST nullify cc3 complete
A suppress A suppress ST nullify cc1 complete TS suppress TS suppress
PT nullify cc3 complete
A suppress A suppress
PT nullify cc2 complete TS suppress TS suppress
P *
A *
Action depends on the type of reference. ST Segment-translation exception.
PT Page-translation exception.
The condition cannot occur because it is recognized as part of the
translation of the instruction address.
A Addressing exception.
P Protection exception.
cc1 Condition code 1 set.
cc2 Condition code 2 set.
2
cc3 Condition code 3 set.
The condition does not apply. Handling of Access Exceptions
cases is summarized in the table "Recognition of
Access Exceptions. " 1. When the instructions COMPARE LOGICAL (CLC or CL), COMPARE LOGICAL CHARACTERS UNDER MASK (CLM) with
a nonzero mask, and COMPARE LOGICAL LONG (CLCL) designate part of an operand
in an inaccessible location but the operation
can be completed by using the accessible oper­
:and parts, it is unpredictable whether the ac­
cess exception for the inaccessible part is indi­
cated.
2. Access exceptions are not indicated for that
part of the first operand (argument) of
TRANSLATE AND TEST (TRT) which is not
used for the completion of the operation.
3. Access exceptions are not indicated for that
part of the second operand (list) of TRANS-
A translation-specification exception for an invalid code in control register 0 bit positions 8-12 is recognized as part of the execution of
the instruction using address translation.
A translation-specification exception for a format error in a table entry
is recognized only when the execution of an instruction requires the
entry for the translation of an address.
LATE (TR) and TRANSLATE AND TEST
(TRT) which is not used for the completion of
the operation.
4. Access exceptions are not indicated for that
part of the second operand (source) of EDIT
(ED) and EDIT AND MARK (EDMK) which
is not used for the completion of the operation.
5. When the instructions MOYE WITH OFFSET (MYO), PACK (PACK), and UNPACK (UNPK) designate part of the second operand
in an inaccessible location but the operation
can be completed by using the accessible oper­
and parts, it is unpredictable whether the ex­
ception for the inaccessible part is indicated. Access exceptions are not indicated for that
part of the second operand (source) of MOYE LONG (MYCL) which is not used for the
completion of the operation.
Interruptions 81

Page of GA22-7000-4 Revised September 1, 1975
By TNL: GN22-0498 Instruction Is an access exception indicatep for that part of the
designated operand which is not used for the completion of the operation ? Instructions that can be completed without
the use of the entire designated or implied operand:
TM (zero mask) GLC,CL GLM (nonzero mask) GLCL TRT (first operand)
TR, TRT (second operand) ED, EDMK (second operand) Instructions in which the second operand may
specify more data than can be processed with
the desi'gnated first operand: PACK, UNPK, MVO MVCL Special cases : IGM, CLM (zero mask) STCM (zero mask) Explancltion: Yes Unpredictable Unpredictable Unpredictable *
No
No
No Unpredictable No
Yes for one byte
No Unprediictable It is unpredictable whether the exception is indicated.
No The exception is not indicated.
Yes The exception is indicated.
For CLCL, no exceptions are indicated other than those for the
current page and the following page of each operand.
Access Hxceptions include the following: protection
addressing
segment translation page translation translatiion specification
Recognition of Access Exceptions
7. 'When the mask in INSERT CHARACTERS UNDER MASK (ICM) and COMPARE LOGICAL CHARACTERS UNDER MASK (CLM) is zero, access exceptions are indicated
for the one byte designated by the second­
operand address.
8. 'When the mask in STORE CHARACTERS UNDER MASK (STCM) is zero, access excep­
tions are not indicated.
The execution of the interruptible instructions COMPARE LOGICAL LONG and MOVE LONG is initiated only when no access exceptions associat­
ed with references to dynamic-address-translation
tables for the initial page of each operand exist, and
the initiation may additionally be contingent on the absence of exceptions associated with table refer­
ences for the following page of each operand. After
the execution of the instruction has been initiated,
an access exception associated with a reference to a
translation table may be indicated as early as when
82 System/370 Principles of Operation
execution has progressed to the point where the last
accessible page of the operand causing the exception
is being processed.
The extent of the operands that is actually used in
the operation may be established in a pretest for
operand accessibility that is performed before the
execution of the instruction is started.
In the case of TRANSLATE (TR), EDIT (ED),
and EDIT AND MARK (EDMK), the initiation of
the execution is contingent only on the .absence of
exceptions associated with dynamic-address­
translation table entries for that part of the second
operand that is actually used for the completion of
the operation.
If the first operand of TR or either operand of ED
or EDMK is changed by an I/O operation, or by
another CPU, after the initial pretest but before
completion of execution, such that an additional
second-operand page is needed and translation of
the address of the additional page causes an access