Bits 16-31 of the second-operand address identify
the channel, the subchannel, and the110 device to
which instruction applies.
When the channel is either available or in the
interruption pending state with the subchannel avail
able or working with the addressed device, HALT
DEVICE causes the addressed device to be selected
and to signaled to terminate the current opera
tion, if any. If the subchannel is working with the
addressed device, HALT DEVICE also causes the
subchannel to be set up to signal termination of the
device operation the next time the device requests or
offers a byte of data, if any. Chaining, ifindkated in
the subchannel, is suppressed. If the sub channel is
available, the sub channel is not affected.
When the channel is either available or in the
interruption pending state with the sub channel either
working with a device other than the one addressed
or in the interruption pending state, no action is tak
en.
When the channel is working in burst mode with
the addressed device, data transfer across the1/0 interface for the operation is immediately tenninat
ed, and the device immediately disconnects from the
channel. Chaining, if indicated in the subcharmel, is
suppressed.
When the channel is working in burst mode with a
device other than the one addressed, and the sub
channel is available, in the interruption pending
state, or working with a device other thanthe; one
addressed, no action is taken. If the sub channel is
working with the addressed device, the sub channel is
set up to signal termination of the device operation
the next time the device requests or offers a byte of
data, if any. Chaining, if indicated in the subchannel,
is suppressed.
When the channel is working in burst mode with a
device other than the one addressed and the sub
channel is not operational, is in the interruption
pending state, or is working with a device other than
the one addressed, the resulting condition code may,
in some channels, be determined by the sub channel
state.
Termination of a burst operation by HALT DE
VICE on a selector channel causes the channel and
sub channel to be placed in the interruption pending
state. Generation of the interruption condition is not
contingent on the receipt of a status byte from the
device. When HALT DEVICE causes a burst opera
tion on a byte-multiplexer channel to be terminated,
the sub channel associated with the burst operation
remains in the working state until the device pro
vides ending status, whereupon the subchannel en
ters the interruption pending state. The termination
of a burst operation by HALT DEVICE on a block-200 System/370 Principles of Operation multiplexer channel may, depending on the model
and the type of subchannel, take place as for a selec
tor channel or may allow the sub channel to remain
in the working state until the device provides ending
status.
When any of the three conditions numbered be
low occurs, HALT DEVICE causes the 16-bit unit
and channel-status portion of theCSW to be re
placed by a new set of status bits. The contents of
the other fields of theCSW are not changed. The CSW stored by HALT DEVICE pertains only to the
execution of HALT DEVICE and does not describe
under what conditions the110 operation at the ad
dressed subchannel is terminated. The extent of data
transfer, and the conditions at the termination of the
operation at the subchannel, are provided in theCSW associated with the interruption condition
caused by the termination. The three conditions are:
1. The addressed device is selected and signaled
to terminate the current operation, if any. TheCSW then contains zeros in the status field
unless a machine malfunction is detected.
2. The control unit is busy and the device cannot
be given the signal to temrinate the operation.
TheCSW unit-status field contains the busy
and status modifier bits. The channel-status
field contains zeros unless a machine malfunc
tion is detected.
3. The channel detects a machine malfunction
during the execution of HALT DEVICE. The
status bits in theCSW then identify the error
condition. The state of the channel and the
progress of the110 operation are unpredicta
ble.
When HALT DEVICE cannot be executed be
cause of a pending logout condition which affects
the operational capability of the channel or subchan
nel, a fullCSW is stored. The fields in the CSW are
all set to zeros, with the exception of the logout
pending bit and the channel control check bit, which
are set to ones. No channel logout is associated with
this status.
When HALT DEVICE causes data transfer over
the110 interface to be terminated, the control unit
associated with the operation remains unavailable
until the data-handling portion of the operation in
the control unit is concluded. Concluding of this
portion of the operation is signaled by the generation
of channel end. This may occur at the normal time
for the operation, or earlier, or later, depending on
the operation and type of device. If the control unit
is shared, all devices attached to the control unit
appear in the working state on that channel until the
channel end condition is accepted by theCPU. The 110 device executing the terminated operation re-
the channel, the subchannel, and the
which
When the channel is either available or in the
interruption pending state with the subchannel avail
able or working with the addressed device, HALT
DEVICE causes the addressed device to be selected
and to
tion, if any. If the subchannel is working with the
addressed device, HALT DEVICE also causes the
subchannel to be set up to signal termination of the
device operation the next time the device requests or
offers a byte of data, if any. Chaining, if
the subchannel, is suppressed. If the sub channel is
available, the sub channel is not affected.
When the channel is either available or in the
interruption pending state with the sub channel either
working with a device other than the one addressed
or in the interruption pending state, no action is tak
en.
When the channel is working in burst mode with
the addressed device, data transfer across the
ed, and the device immediately disconnects from the
channel. Chaining, if indicated in the subcharmel, is
suppressed.
When the channel is working in burst mode with a
device other than the one addressed, and the sub
channel is available, in the interruption pending
state, or working with a device other than
addressed, no action is taken. If the sub channel is
working with the addressed device, the sub channel is
set up to signal termination of the device operation
the next time the device requests or offers a byte of
data, if any. Chaining, if indicated in the subchannel,
is suppressed.
When the channel is working in burst mode with a
device other than the one addressed and the sub
channel is not operational, is in the interruption
pending state, or is working with a device other than
the one addressed, the resulting condition code may,
in some channels, be determined by the sub channel
state.
Termination of a burst operation by HALT DE
VICE on a selector channel causes the channel and
sub channel to be placed in the interruption pending
state. Generation of the interruption condition is not
contingent on the receipt of a status byte from the
device. When HALT DEVICE causes a burst opera
tion on a byte-multiplexer channel to be terminated,
the sub channel associated with the burst operation
remains in the working state until the device pro
vides ending status, whereupon the subchannel en
ters the interruption pending state. The termination
of a burst operation by HALT DEVICE on a block-
and the type of subchannel, take place as for a selec
tor channel or may allow the sub channel to remain
in the working state until the device provides ending
status.
When any of the three conditions numbered be
low occurs, HALT DEVICE causes the 16-bit unit
and channel-status portion of the
placed by a new set of status bits. The contents of
the other fields of the
execution of HALT DEVICE and does not describe
under what conditions the
dressed subchannel is terminated. The extent of data
transfer, and the conditions at the termination of the
operation at the subchannel, are provided in the
caused by the termination. The three conditions are:
1. The addressed device is selected and signaled
to terminate the current operation, if any. The
unless a machine malfunction is detected.
2. The control unit is busy and the device cannot
be given the signal to temrinate the operation.
The
and status modifier bits. The channel-status
field contains zeros unless a machine malfunc
tion is detected.
3. The channel detects a machine malfunction
during the execution of HALT DEVICE. The
status bits in the
condition. The state of the channel and the
progress of the
ble.
When HALT DEVICE cannot be executed be
cause of a pending logout condition which affects
the operational capability of the channel or subchan
nel, a full
all set to zeros, with the exception of the logout
pending bit and the channel control check bit, which
are set to ones. No channel logout is associated with
this status.
When HALT DEVICE causes data transfer over
the
associated with the operation remains unavailable
until the data-handling portion of the operation in
the control unit is concluded. Concluding of this
portion of the operation is signaled by the generation
of channel end. This may occur at the normal time
for the operation, or earlier, or later, depending on
the operation and type of device. If the control unit
is shared, all devices attached to the control unit
appear in the working state on that channel until the
channel end condition is accepted by the