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Condition-Code Settings
I/O
SID
I/O-System States
State
SIOF TID CLRIO
HID HDV TCH STIDC
Available
AAA
0,1 *@
0
0
1*
1*
0
0
Interruption pending in device
AAI
1*@
1*
0
1*
1*
0
0
Device working
AAW
1*@
1*
0
1*
1*
0
0
Device not operational
AAN
3@
3
0
3
3
0
0
Interruption pending in subchannel
AIX
For the addressed device
2
1*
1*
0
0
0
0
For another device
2
2
0
0
0
0
0
Subchannel working
AWX
With the addressed device
2
2
1*
1*# 1*#
0
0
With another device
2
2
0
1*#
0
0
0
Subchannel not operational
ANX
3
3
3
3
3
0
0
Interruption pending in channel
IXX
---See Note
1
##
Channel working
WXX
With the addressed device
2
2
***
2
+
2
##
With another device
2
2-
**
2
~
2
##
Internal activity
2
2-
**
2
~
2
##
Channel not operat i ona I
NXX
3
3
3
3
3
3
3
Explanation:
*
Whenever condition code 1 is set, the CSW or its
status
portion
is
stored at location
64
during execution of the instruction.
**
When
CLEAR
I/O encounters the WXX state, either condition code
2
is
set, or the channel is treated as available and the condition code is
set according to the state of the subchannel.
When
the
channel
is
treated
as available, the condition codes for the WXX states are the
same as for the AXX states.
***
Condition code
1
(with the CSW stored) or
2
may be set,
the channel.
depending on
~
The
condition
code
depends
on
the
state
of the subchannel, the
channel type, and
the
system
model.
If
the
subchannel
is
not
operational, condition
code
2
or
3
is set.
If the subchannel is
available
or working with the addressed device,
condition code
2
is
set.
Otherwise, condition code
0
or
2
is set.
#
When a "device not operational
ll
response is received in selecting the
addressed device, condition code
3
is set.
@
START I/O FAST RELEASE may cause the same condition code to be set as
for START I/O or may cause condition code 0 to be set.
+
If the channel ascertains that the device received the signal to ter-
minate,
condition
code
1
is
set and the
CSW stored.
Otherwise,
condition code
2
is set.
##
When the channel is unable to store the channel
ID
because
of
the
working or interruption-pending
state, condition code
2
is set.
If
the
working
or interruption-pending state does not preclude storing
the channe
I
I D, cond i t i on code
0
is set.
-
If the subchannel is interruption-pending for the
addressed
device,
condition code
1
may be set depending on the channel type.
Note:
For the
purpose of
executing
START I/O, START I/O FAST RELEASE,
TEST I/O, CLEAR I/O, HALT DEVICE, and
HALT I/O, a
channel containing an
interruption condition
appears the same as an available channel, and the
condition-code setting
depends on the
states of the
subchannel and de-
vice.
The condition codes for the IXX states are the same as for the AXX
states, where the
XS
represent the states of the subchannel and the de-
vice.
As an example, the condition code for the lAW state is the same as
for AAW.
Condition-Code Settings for I/O States and Instructions
12-12
IBM 4300 Processors Principles
of
Operation
(
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