The system control panel contains the switches and
lights necessary to operate and control the system.
The system consists of theCPU, storage, channels, on
line control units, andI/O devices. Off-line control
units andI/O devices, although part of the system
environment, are not considered part of the system
proper.
System controls are divided into three sections:
operator control, operator intervention, and customer
engineering control. Customer engineering controls
are also available on some storage, channel, and con
trol-unit frames.
No provision is made for locking out any section of
the system control panel. The conditions under which
individual controls are active are described for each
case.System Control Functions
The system-reset function resets theCPU, the channels,
panel are the ability to reset the system; to store and
display information in storage, in registers and in thePSW; and to load initial program information.
System Reset
The system-reset function resets theCPU, the channels,
and on-line, nonshared control units andI/O devices.
TheCPU is placed in the stopped state and all pend
ing interruptions are eliminated. The parity of general
and floating-point registers, as well as the parity of thePSW, may be corrected. All error-status indicators are
reset to zero.
In general, the system is placed in such a state that
processing can be initiated without the occurrence of
machine checks, except those caused by subsequent
machine malfunction.
The reset state for a control unit or device is de
scribed in the appropriate System Reference Library(SRL) publication. Off-line control units are not reset.
A system-reset signal from aCPU resets only the
functions in a shared control unit or device belonging
to thatCPU. Any function pertaining to another CPU remains undisturbed.
The system-reset function is performed when the
system-reset key is pressed, when initial program
SystemControl Panel loading is initiated, or when a power-on sequence is
performed.
Programming Notes
Because the system reset may occur in the middle of
an operation, the contents of the psw and of result
registers or storage locations are unpredictable. If theCPU is in the wait state when the system reset is per
formed, andI/O is not operating this uncertainty is
eliminated.
Following a system reset, incorrect parity may exist
in storage in all models and in the registers in some
models.Since a machine check occurs when informa
tion with incorrect parity is used, the incorrect in
formation should be replaced by loading new infor
mation.
Store andDisplay The store-and-display function permits manual inter
vention in the progress of a program. The store-and
display function may beprOVided by a supervisor
program in conjunction with properI/O equipment
and the interrupt key.
In the absence of an appropriate supervisor pro
gram, the controls on the operator intervention panel
permit theCPU to be placed in the stopped state and
subsequently to store and display information in main
storage, in general and floating-point registers, and in
the instruction-address part of the psw. The stopped
state is achieved at the end of the current instruction
when the stop key is pressed, when single instruction
execution is specified, or when a preset address is
reached.Once the desired intervention is completed,
theCPU can be started again.
All basic store-and-display functions can be simu
lated by a supervisor program. The stopping and start
ing of theCPU in itself does not cause any alteration
in program execution other than the time element in
volved (the transition from operating to stopped state
is described under"Stopped State" in "Status-Switch ing"). Interruption checks occurring during store-and-dis
play functions do not interrupt or log immediately but
may, in some cases, create a pending interruption. This
interruption request can be removed by a system re
set.Otherwise, the interruption, when not masked off,
is taken when theCPU is again in the operating state.
System ControlPanel 117
lights necessary to operate and control the system.
The system consists of the
line control units, and
units and
environment, are not considered part of the system
proper.
System controls are divided into three sections:
operator control, operator intervention, and customer
engineering control. Customer engineering controls
are also available on some storage, channel, and con
trol-unit frames.
No provision is made for locking out any section of
the system control panel. The conditions under which
individual controls are active are described for each
case.
The system-reset function resets the
panel are the ability to reset the system; to store and
display information in storage, in registers and in the
System Reset
The system-reset function resets the
and on-line, nonshared control units and
The
ing interruptions are eliminated. The parity of general
and floating-point registers, as well as the parity of the
reset to zero.
In general, the system is placed in such a state that
processing can be initiated without the occurrence of
machine checks, except those caused by subsequent
machine malfunction.
The reset state for a control unit or device is de
scribed in the appropriate System Reference Library
A system-reset signal from a
functions in a shared control unit or device belonging
to that
The system-reset function is performed when the
system-reset key is pressed, when initial program
System
performed.
Programming Notes
Because the system reset may occur in the middle of
an operation, the contents of the psw and of result
registers or storage locations are unpredictable. If the
formed, and
eliminated.
Following a system reset, incorrect parity may exist
in storage in all models and in the registers in some
models.
tion with incorrect parity is used, the incorrect in
formation should be replaced by loading new infor
mation.
Store and
vention in the progress of a program. The store-and
display function may be
program in conjunction with proper
and the interrupt key.
In the absence of an appropriate supervisor pro
gram, the controls on the operator intervention panel
permit the
subsequently to store and display information in main
storage, in general and floating-point registers, and in
the instruction-address part of the psw. The stopped
state is achieved at the end of the current instruction
when the stop key is pressed, when single instruction
execution is specified, or when a preset address is
reached.
the
All basic store-and-display functions can be simu
lated by a supervisor program. The stopping and start
ing of the
in program execution other than the time element in
volved (the transition from operating to stopped state
is described under
play functions do not interrupt or log immediately but
may, in some cases, create a pending interruption. This
interruption request can be removed by a system re
set.
is taken when the
System Control