Channel
A None of the following states Available
Interruption pending I Interruption immediately available
from channel
Working
Not operational
W Channel operating in burst mode
N Channel not operational
A None of the following states
Subchannel
Available
Interruption pending I Information for CSW available in
subchannel
Working
Not operational
W Subchannel executing an operation
N Subchannel not operational Condition Code Setting for Input / Output Instructions CONDITIONS Available
Interruption pend. in device
Device working
Device not operational
Interruption pend. in subchannel
For the addressed device
For another device Subchannel working Subchannd not operational
Interruption pend. in channel Channel working Channel not operational
Error
AAA
AAI
AAW
AAN
AIX
AWX
ANX
IXX
WXX
NXX CONDITION CODE FOR START TEST HALT TEST I/O I/O I/O CHAN 0,1 0 0 0 P' 1"'" 0 0 1"'" 1"'" 0 0 3 3 0 0 2 1"'" 0 0 2 2 0 0 2 2 1"'" 0 3 3 3 0 see note below 1
2 2 2 2
3 3 3 3 Channel equipment error 1"'" 1 \) 1 "'" Channel programming error 1 "'" Device error 1 "'" 1 "'" NOTE: For the purpose of executing START I/O, TEST I/O, and HALT I/O, a channel containing a pending interruption
condition appears the same as an available channel, and the
condition codes for the IXX state arc 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 code for the IAA
state is the same as for the AAA state. ""'The CS\" or its status portion is stored at location 64 during
execution of the instruction.
-The condition cannot he identified during execution of the in­
struction. Flag Setting for Chaining Operations
CD ACTION
o
CC
o No chaining. The current CCW is the last.
The operation is terminated
o
1
1
1
o
1 Command chaining
Data chaining
Data chaining Content of Channel Status Word Address Field CONDITION Channel control check Status stored by START I/O Status stored by HALT I/O Invalid CCW address spec. in TIC Invalid CCW address in TIC Invalid CGW address
generated
Invalid command code
Invalid count
Invalid data address
154 CONTENT U npredicta ble
Unchanged Unchanged Address of TIC + 8
Address of TIC + 8
Address of first invalid CCW +8
Address of invalid CCW + 8
Address of invalid CCW + 8
Address of invalid CCW + 8 CONDITION Invalid CCW format
Invalid sequence -2 TIC's Protcction check Chaining check
Termination under count
control
Termination by I/O device
Termination by HALT I/O Suppression of command
chaining due to unit check
or unit exception with de­
vice end or control unit end
Termination on command
chaining by attention, unit
check, or unit exception
Program-controlled interrup-
tion
Interface control check Ch. end after HIO on seI. ch. Control unit end
Dcvice end
Attention
Busy Status modifier CONTENT Address of invalid CCW + 8
Address of second TIC + 8
Address of invalid CCW + 8
Address of last-used CCW + 8
Address of last-used CCW + 8
Address of last-used CCW + 8
Address of last-used CCW + 8
Address of last CCW used in
the completed operation + 8
Address of CCW specifying
the new operation + 8
Address of last-used CCW + 8
Address of last-used CCW + 8 Zero Zero Zero Zero Zero Zero Content of Channel Status Word Count Field CONDITION Channel control check
Status stored by START I/O Status stored by HALT I/O Program check
Protection check Chaining check
Termination under count
control
Termination by I/O device
Termination by HALT I/O Suppression of command chaining duc to unit check
or unit exception with device
end or control unit end
Termination on command
chaining by attention, by
unit check, or unit
exception
Program-controlled inter-
ruption
Interface control check
eh. end after HIO on sel. ch. Control unit end
Devicc end
Attention Busy Status Modifier CONTENT Unpredictable Unchanged Unchanged Unpredictable U npredicta ble Correct Correct Correct Correct Correct. Residual count of last CCW used in the completed
operation. Correct. Original count of CCW specifying the new
operation.
Unpredictable Correct Zero Zero Zero Zero Zero Zero Indication of Busy Condition in Channel Status Word
The table lists the conditions when the busy bit (B)
appears in the csw and when it is accompanied by
the status-modifier bit (8M). Two hyphens (--) incli­
cate that the busy bit is off; an asterisk (#) indicates
that csw status is not stored or an I/O interruption
cannot occur; the (cl) indicates that the interruption
condition is cleared and the status appears in the csw.
The abbreviation DE stands for device end, and cu
stands for control unit.

CSW STATUS STORED BY: Handling of Length START TEST HALT I/O I/O I/O I/O FLAGS ACTION AND INDICATION CONDITION INT.
CD CC SLI REGULAH OPERATION IMMEDIATE OPERATION Subchannel available 0 0 0 Stop,IL Stop, --
DE or attention in device B,d --,d '" --,d
Device working, CD available B B '" '" 0 0 1 Stop, -- Stop, -- 0 1 0 Stop,IL Chain command CU end or channel end in CU: 0 1 1 Chain command Chain command
for the addressed device B,d --,d '" --,d
for another device B,SM B,SM '" --,d
1 0 0 Stop,IL Stop, -- CU working B,SM B,SM '" '" 1 0 1 Stop,IL Stop, --
I 1 0 Stop,IL Stop, --
Interruption pend. in sub channel
1 1 1 Stop,IL Stop, --
for the addressed device
because of:
chaining terminated by
attention '" B,d '" B,d
other type of termination '" --,d '" --,cl
Subchannel working CU available '" '" '" CU working '" '" B,SM <I< Time and Method of Creating and Storing Status Indications WHEN WHEN UPON TERMINATION OF OPERATION DURING BY BY BY BY I/O STATUS Attention Status modifier Control unit end
Busy Channel end
Device end Unit check U nit exception
Program-controlled interruption
Incorrcct length Program check
Protection check Channel data check Channel control check
Interface control check Chaining check NOTES I/O IS IDLE CO CO CO co SUBCHANNEL AT
WORKING SUBCHANNEL CO C C C'" C C C C C C C co C co C'" co C'" C C C- The channel or the device can create or present the status
condition at the indicatcd time. A CSW or its status portion is
not necessarily stored at this time.
Conditions such as channel end amI devicc end are created at
the indicated time. Other conditions may have been created
previously, but are made accessible to the program only at thc
indicated time. Examples of such conditions arc program check
and channel data check, which are detected while data arc
transferred, but are made available to the program only with
channel end, unless the PCI flag or equipment malfunctioning
havc caused an interruption condition to be generated earlier. S- The status indication is stored in the CSW at the indicated
time.
An S appearing alone indicates that the condition has been
created previously. The letter C appearing with the S indicates
that the status condition did not necessarily exist previously in
the form that causes the program to be alerted, and may have AT CONTROL AT COMMAND START TEST HALT INTER- UNIT DEVICE CHAINING I/O I/O I/O RUPTION - - --- ---- C CO S S S C C CS CS CS S CO CS CS CS S C CS CS CS S C"'H C<>·!· Ct S S S CO c t Gr S S S C C C'" CS CS CS C C C'" CS S S C CS S S S S C'" CS S S S S S S CO CO C'" CS CS CS CS co CO C'" CS CS CS CS S S bccn created by the I/O instruction or I/O interruption. For
example, equipment malfunctioning may be detected during an I/O interruption, causing channel control check or interface
control check to be indicated; or a device such as the 2702 Transmission Control Unit may signal the control-un it-busy
condition in response ,to interrogation by an I/O instruction,
causing status modifier, busy, and control unit end to be indi­
catcd in the CSW. "'-The status condition generates or, in the case of channel
data check, may generate an interruption condition. Channel end and dcvice end do not result in interruption
conditions when command chaining is spccified and no unusual
conditions have bccn detected. 1"- This status indication can be created at the indicated time
only by an immediate operation.
H-When an operatioll1 on the selector channel has been termi­
natcd by HALT I/O, channel end indicates the termination of
the data-handling portion of the operation at the control unit.
Appendix G 155