Explanation:
Locations for the oldPSWs, new PSWs, and interruption codes are real locations.
1 A model-independent machine-check interruption code of 64 bitsis stored at
real locations 232-239. In the BC mode, the contents of real locations50-51 are unpredictable.
2 The effect of the machine-check condition is indicated by bits in the machine
check-interruptioncode. The setting of these bits indicates the extent of
the damage and whether the unit of operationis nullified, terminated, or
unaffected.
3 The interruption code in the column labeled "Hex" is thehex code for the
basic interruption; this code does not show the effects of concurrent inter
ruption conditions represented bye, n, p, or xin the column labeled "Binary." 4 Vector-operation and unnormalized-operand exceptions are associated with
the vector facility."Inhibited" is a type of ending which occurs only for
instructions associated with the vector facility. These are described in
the publication IBMSystem/370 Vector Operations, SA22-7125. 5 When the interruption code indicates a PER event, an ILC of 0 may be stored
only when bits8-15 of the interruption code are 10000110 (PER, specifi
cation).
6 The unit of operation is completed, unless a program exception concurrently
indicated causes the unit of operation tobe inhibited, nullified, suppressed,
or terminated.
7 For channels0-5, channel masks in control register 2 have no effect in the
BC mode.s Bits 16-31 in the old PSW in the BC mode are set to zeros. No interruption
code is provided in the EC mode.
+Plus the following bits in the control register. One mask bit is provided for
each installed channel; the bitposition matches the channel address. * In the BC mode, PER is disabled. Additional masks in control register 9, bit positions 16-31, provide detailed
control over the source ofPER general-register-alteration events which are masked by control register 9, bit 3.
c Channel-address bits.
d Device-address bits.
e If one, thebit indicates another concurrent external-interruption condition.
n A possible nonzero code, indicating another concurrent program-interruption
condition.
p If one, the bit indicates a concurrentPER-event interruption condition.
s Bits of the I field ofSUPERVISOR CALL.
u Unpredictable in the BC mode; not stored in the EC mode.
x Exception-extension code. This field is described in the publication IBMSystem/370 Vector Operations, SA22-7125. This field is set to zero except by
vector instructions.
Interruption Action(Part 3 of 3) INTERRUPTION CODE The six classes of interruptions
(external,I/O, machine check, program,
restart, and supervisor call) are
distinguished by the storage locations
atwhich the old PSW is stored and from
which the newPSW is fetched. For most
classes, the causes are further identi
fied by an interruption code and, for
some classes, by additional information
placed in permanently assigned real
storage locations during the inter
ruption.(See also the section "Assigned Storage Locations" in Chapter
3,"Storage.") For external, I/O, program, and supervisor-call inter-
ruptions, the interruption code consists of 16 bits. In the BC mode, the inter al ruption code is zero in the PSW stored '1 by the store-status function and is 1 unpredictable when the PSW is displayed.
For external interruptions in the EC
mode, the interruption code is stored at
real locations 134-135. In the BC mode,
the interruption code is placed in the
oldPSW. A parameter may be stored at
real locations 128-131, ora CPU address
may be stored at real locations 132-133.
ForI/O interruptions in the EC mode,
the interruption code, which contains
theI/O address, is stored at real
locations 186-187. In the BC mode, the
interruption code is placed in the oldPSW. Additional information is provided
by the contents of the channel-status
word(CSW) stored at real location 64.
Further information may be provided by
the limited channel logout stored at
real locations 176-179 and by a full
channel logout stored in the fixed
logoutarea (real locations 256-351) or
in the I/O-extended-Iogout area.
Chapter 6. Interruptions 6-5
Locations for the old
1 A model-independent machine-check interruption code of 64 bits
real locations 232-239. In the BC mode, the contents of real locations
2 The effect of the machine-check condition is indicated by bits in the machine
check-interruption
the damage and whether the unit of operation
unaffected.
3 The interruption code in the column labeled "Hex" is the
basic interruption; this code does not show the effects of concurrent inter
ruption conditions represented bye, n, p, or x
the vector facility.
instructions associated with the vector facility. These are described in
the publication IBM
only when bits
cation).
6 The unit of operation is completed, unless a program exception concurrently
indicated causes the unit of operation to
or terminated.
7 For channels
BC mode.
code is provided in the EC mode.
+
each installed channel; the bit
control over the source of
c Channel-address bits.
d Device-address bits.
e If one, the
n A possible nonzero code, indicating another concurrent program-interruption
condition.
p If one, the bit indicates a concurrent
s Bits of the I field of
u Unpredictable in the BC mode; not stored in the EC mode.
x Exception-extension code. This field is described in the publication IBM
vector instructions.
Interruption Action
(external,
restart, and supervisor call) are
distinguished by the storage locations
at
which the new
classes, the causes are further identi
fied by an interruption code and, for
some classes, by additional information
placed in permanently assigned real
storage locations during the inter
ruption.
3,
ruptions, the interruption code consists
For external interruptions in the EC
mode, the interruption code is stored at
real locations 134-135. In the BC mode,
the interruption code is placed in the
old
real locations 128-131, or
may be stored at real locations 132-133.
For
the interruption code, which contains
the
locations 186-187. In the BC mode, the
interruption code is placed in the old
by the contents of the channel-status
word
Further information may be provided by
the limited channel logout stored at
real locations 176-179 and by a full
channel logout stored in the fixed
logout
in the I/O-extended-Iogout area.
Chapter 6. Interruptions 6-5