The key is effective only while the CPU is in the
stopped state.Storage-Select Switch The storage area to be addressed by the address
switches is selected by the storage-select switches.
The switch can select main storage, the general reg
isters, the floating-point registers and, in some cases,
the instruction-address part of the psw.
When the general or floating-point registers are not
addressed directly but must be addressed by using
another address such as a local-store location, infor
mation is included on the panel to enable an operator
to compute the required address.
The switch can be manipulated without disruptingCPU operations.
Address Switches
The address switches address a location in a storage
area and can be manipulated without disruptingCPU operation. The address switches, with the storage-se
lect switch, permit access to any addressable location.
Correct address parity is generated.
Data Switches
The data switches specify the data to be stored in the
location specified by the storage-select switch and ad
dress switches.
The number of data switches is sufficient to allow
storing of a full physical storage word. Correct data
parity is generated. Some models generate either cor
rect or incorrect parity under switch control.Store Key
The store key is pressed to store information in the
location specified by the storage-select switch and ad
dress switches.
The contents of the data switches are placed in the
main storage, general register, or floating-point .regis
ter location specified. Storage protection is ignored.
When the location designated by the address switches
and storage-select switch is not available, data are not
stored.
The key is effective only while theCPU is in the
stopped state.
Display Key
The display key is pressed to display information in
the location specified by the storage-select switch and
address switches.
The data in the main storage, general register, or
floating-point register location, or in the instruction-
address part of the psw specified by the address
switches and the storage-select switch, are displayed.
When the designated location is not available, the dis
played information is unpredictable. In some models,
the current instruction address is continuously dis
played and hence is not explicitly selected.
The key is effective only while theCPU is in the
stopped state.Set IC Key
This key is pressed to enter an address into the in
struction-address part of the current psw.
The key is effective only while theCPU is in the
stopped state.
The address in the address switches is entered in
bits40-63 of the current psw. In some models the ad
dress is obtained from the data switches.Address-Compare Switches
These rotary or key switches provide a means of stop
ping theCPU on a successful address comparison.
When these switches are set to the stop position,
the address in the address switches is compared
against the value of the instruction address on all
models and against all addresses on some models. An
equal comparison causes theCPU to enter the stopped
state. Comparison includes only the part of the in
struction address that addresses the physical word size
of storage.
Comparison of the entire halfword instruction ad
dress is provided in some models, as is the ability to
compare data addresses.
The address-compare switches can be manipulated
without disruptingCPU operation other than by caus
ing the address-comparison stop. When they are set
to any position but normal, the test light is on.
Programming Note
When an address not used in the program is selected
in the address switches, theCPU runs as if the address
compare switches were set to normal, except for the
reduction in performance which may be caused by the
address comparison.
Alternate-Prefix Light
The alternate-prefix light is on when the prefix trigger
is in its alternate state. The light is part of the multi
system feature.
Customer Engineering Section
This section of the system control panel contains con
trols intended only for customer-engineering use.System Control Panel 121
stopped state.
switches is selected by the storage-select switches.
The switch can select main storage, the general reg
isters, the floating-point registers and, in some cases,
the instruction-address part of the psw.
When the general or floating-point registers are not
addressed directly but must be addressed by using
another address such as a local-store location, infor
mation is included on the panel to enable an operator
to compute the required address.
The switch can be manipulated without disrupting
Address Switches
The address switches address a location in a storage
area and can be manipulated without disrupting
lect switch, permit access to any addressable location.
Correct address parity is generated.
Data Switches
The data switches specify the data to be stored in the
location specified by the storage-select switch and ad
dress switches.
The number of data switches is sufficient to allow
storing of a full physical storage word. Correct data
parity is generated. Some models generate either cor
rect or incorrect parity under switch control.
The store key is pressed to store information in the
location specified by the storage-select switch and ad
dress switches.
The contents of the data switches are placed in the
main storage, general register, or floating-point .regis
ter location specified. Storage protection is ignored.
When the location designated by the address switches
and storage-select switch is not available, data are not
stored.
The key is effective only while the
stopped state.
Display Key
The display key is pressed to display information in
the location specified by the storage-select switch and
address switches.
The data in the main storage, general register, or
floating-point register location, or in the instruction-
address part of the psw specified by the address
switches and the storage-select switch, are displayed.
When the designated location is not available, the dis
played information is unpredictable. In some models,
the current instruction address is continuously dis
played and hence is not explicitly selected.
The key is effective only while the
stopped state.
This key is pressed to enter an address into the in
struction-address part of the current psw.
The key is effective only while the
stopped state.
The address in the address switches is entered in
bits
dress is obtained from the data switches.
These rotary or key switches provide a means of stop
ping the
When these switches are set to the stop position,
the address in the address switches is compared
against the value of the instruction address on all
models and against all addresses on some models. An
equal comparison causes the
state. Comparison includes only the part of the in
struction address that addresses the physical word size
of storage.
Comparison of the entire halfword instruction ad
dress is provided in some models, as is the ability to
compare data addresses.
The address-compare switches can be manipulated
without disrupting
ing the address-comparison stop. When they are set
to any position but normal, the test light is on.
Programming Note
When an address not used in the program is selected
in the address switches, the
compare switches were set to normal, except for the
reduction in performance which may be caused by the
address comparison.
Alternate-Prefix Light
The alternate-prefix light is on when the prefix trigger
is in its alternate state. The light is part of the multi
system feature.
Customer Engineering Section
This section of the system control panel contains con
trols intended only for customer-engineering use.