generated
Invalid command code
Invalid count
Invalid data address
Invalid
Invalid sequence -2 TIC's
Protection check
Chaining check
Termination under count
control
Termination by
Termination by HALT
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
Control unit end
Device end
Attention
Busy
Count
CONTENT
Unpredictable
Unchanged
Unchanged
Address of
Address of
Address first invalid
Address of invalid
Address of invalid
Address of invalid
Address of invalid
Address of second
Address of invalid
Address of last-used
Address of last-used
Address of last-used
Address of last-used
Address of last
the completed operation + 8
Address of
the new operation + 8
Address of last-used
Address of last-used
count specified in the last ccw used, indicates the
number of bytes transferred to or from the area desig
nated by the ccw. When an input operation is termi
nated, the difference between the original count in the
ccw and the residual count in the csw is equal to the
number of bytes transferred to main storage; on an out
put operation, the difference is equal to the number
of bytes transferred to the
The following table lists the contents of the count
field for all conditions that can cause the csw to be
stored. The conditions are listed in the order of prior
ity; that is, if two conditions are indicated or occur,
the csw appears as for the condition higher on the list.
CONDITION
Channel control check
Protection check
Chaining check
Termination under count
control
Termination by
Termination by HALT
chaining due to unit check,
unit exception with device
end, or control unit end
Termination on command
chaining by atention, by
unit check, or unit
exception
Program-controlled inter-
ruption
Interface control check
Control unit end
Device end
Attention
Busy
Status
Unchanged
Unchanged
Unpredictable
Unpredictable
Correct
Correct
Correct
Correct
Correct. Residual count of last
operation.
Correct.
operation.
Unpredictable
Correct
detected during the
command to be rejected, or that have been generated
by external events.
The csw contains at least one status bit, unless it is
stored by HALT
or the interruption condition responsible for the stor
ing is caused by HALT r/o issued to the selector chan
nel. In both of the latter cases, all status bits may be
off.
When the channel detects several error conditions,
all conditions may be indicated or only one may ap
pear in the csw, depending on the condition and
model. Conditions associated with equipment mal
fU'hctioning have precedence, and whenever maHunc
tioning causes an operation to be terminated, channel
control check, interface control check, or channel data
check is indicated, depending on the condition. When
an operation is terminated by program check, pro
tection check, or chaining check, the channel identifies