The following table lists the conditions that are
identified and the corresponding condition codes for
each instruction. The states of the system and their
abbreviations are defined in"States of the Input/Out put System." The digits in the table represent the
numeric value of the code. The instructionSTART I/O can set code 0 or 1 for the AAA state, depending on
the type of operation that is initiated.
CONDITIONCODE FOR START TEST HALT TEST CONDITIONS I/O I/O I/O CHAN
Available AAA0 0 0 Interruption pend. in device AAI 0 0 Device working AAW 0 0 Device not operational AAN 3 3 0 0 Interruption pend. in sub channel AIX
For the addressed device 20 0 For another device 2 2 0 0 Subchannel working AWX 2 2 0 Subchannel not operational ANX 3 3 3 0 Interruption pend. in channel IXX sce note below 1 Channel working WXX 2 2 2 2 Channel not operational NXX 3 3 3 3 Error Channel equipment error P P Channel programming error Device error CSW or its status portion is stored at location 64 during
execution of the instruction.
- The condition cannot be identified during execution of the in
struction.NOTE: For the purpose of executing START I/O, TEST I/O,
and HALTI/O, a channel containing a pending interruption
condition appears the same as an available channel, and the
condition codes for the IXX state are the same as for the AXX
state, where the X's represent the states of the subchannel and
the device. As an example, the condition eode for the IAA
state is the same as for the AAA state.
The available condition is indicated only when no
errors are detected during the execution of theI/O instruction. When a programming error occurs in the
information placed in theCAW or ccw and the ad
dressed channel or subchannel is working, either con
dition code 1 or 2 may be set, depending upon the
model. Similarly, either code 1 or 3 may be set when
a programming error occurs and a part of the ad
dressedI/O system is not operational.
When a subchannel on the multiplexor channel con
tains a pending interruption condition (state AIX),
theI/O device associated with the terminated opera
tion normally is in the interruption-pending state.
When the channel detects during execution ofTEST I/O that the device is not operational, condition code
3 is set. Similarly, condition code 3 is set when HALTI/O is addressed to a subchannel in the working state
and operating in the multiplex mode (state A WX ) ,
but the device turns out to be not operational. The
not-operational state in both situations can be caused
by operator intervention or by equipment malfunction
and, for HALTI/O, may occur when the isntruction is
addressed to a control unit other than the one cur
rently operating.
The error conditions listed in the preceding table
include all equipment or programming errors detected
by the channel or theI/O device during execution of
theI/O instruction. Except for channel equipment er
rors, in which case no csw may be stored, the status
portion of the csw identifies the error. Three types of
errors can occur:
Channel Equipment Error: The channel can detect
the following equipment errors during execution ofSTART r/o, TEST I/O, and HALT r/o:
1. The device address that the channel received on
the interface during initial selection either has a
parity error or is not the same as the one the channel
sent out.Some device other than the one addressed
may be malfunctioning.
2. The unit-status byte that the channel received on
the interface during initial selection has a parity error.
3. A signal from theI/O device occurred during
initial selection at an invalid time or had invalid
duration.
4. The channel detected an error in its control
equipment.
The channel may perform the malfunction-reset
function, depending on the type of error and the
model. If a csw is stored, channel control check or
interface control check is indicated, depending on the
type of error.
Channel Programming Error: The channel can de
tect the following programming errors during execu
tion ofSTART I/O: 1. Invalid ccw address in CAW 2. Invalid ccw address specification in CAW 3. Invalid storage protection key in CAW 4. Invalid CAW format
5. First ccw specifies transfer in channel
6. Invalid command code in first ccw
7. Initial data address exceeds addressing capacity
of model
8. Invalid count in first ccw
9. Invalid format of first ccw
The csw indicates program check.
Device Error: Programming or equipment crrors
detected by the device during the execution ofSTART I/O are indicated by unit check or unit exception in
the csw. The instructionTEST I/O can cause unit check
to be generated.
The conditions responsible for unit check and unit
exception for each type of1/0 device are detailed in
theSRL publication for the device.
[nput/Output Operations 91
identified and the corresponding condition codes for
each instruction. The states of the system and their
abbreviations are defined in
numeric value of the code. The instruction
the type of operation that is initiated.
CONDITION
Available AAA
For the addressed device 2
execution of the instruction.
- The condition cannot be identified during execution of the in
struction.
and HALT
condition appears the same as an available channel, and the
condition codes for the IXX state are the same as for the AXX
state, where the X's represent the states of the subchannel and
the device. As an example, the condition eode for the IAA
state is the same as for the AAA state.
The available condition is indicated only when no
errors are detected during the execution of the
information placed in the
dressed channel or subchannel is working, either con
dition code 1 or 2 may be set, depending upon the
model. Similarly, either code 1 or 3 may be set when
a programming error occurs and a part of the ad
dressed
When a subchannel on the multiplexor channel con
tains a pending interruption condition (state AIX),
the
tion normally is in the interruption-pending state.
When the channel detects during execution of
3 is set. Similarly, condition code 3 is set when HALT
and operating in the multiplex mode (state A WX ) ,
but the device turns out to be not operational. The
not-operational state in both situations can be caused
by operator intervention or by equipment malfunction
and, for HALT
addressed to a control unit other than the one cur
rently operating.
The error conditions listed in the preceding table
include all equipment or programming errors detected
by the channel or the
the
rors, in which case no csw may be stored, the status
portion of the csw identifies the error. Three types of
errors can occur:
Channel Equipment Error: The channel can detect
the following equipment errors during execution of
1. The device address that the channel received on
the interface during initial selection either has a
parity error or is not the same as the one the channel
sent out.
may be malfunctioning.
2. The unit-status byte that the channel received on
the interface during initial selection has a parity error.
3. A signal from the
initial selection at an invalid time or had invalid
duration.
4. The channel detected an error in its control
equipment.
The channel may perform the malfunction-reset
function, depending on the type of error and the
model. If a csw is stored, channel control check or
interface control check is indicated, depending on the
type of error.
Channel Programming Error: The channel can de
tect the following programming errors during execu
tion of
5. First ccw specifies transfer in channel
6. Invalid command code in first ccw
7. Initial data address exceeds addressing capacity
of model
8. Invalid count in first ccw
9. Invalid format of first ccw
The csw indicates program check.
Device Error: Programming or equipment crrors
detected by the device during the execution of
the csw. The instruction
to be generated.
The conditions responsible for unit check and unit
exception for each type of
the
[nput/Output Operations 91