IBM System/370 145 Operating Procedures Manual page 24

KEY
FUNCTION
CHECK RESET
Resets all machine check circuitry.
START CONSOLE
Starts a console file read operation.
FILE
SET CONTROL
Causes the value set in rotary switches EFGH to address
STORAGE ADDRESS
control storage when the start key is operated. This Is a
service function.
ENABLE SYSTEM Used with SYSTEM RESET or LOAD key to clear program
CLEAR storage. See the Clear Storage Procedure.
Loads the contents of switches CDEFGH into the
SETIC instruction counter. I nstruction processing starts from this
address.
DISPLAY
Displays main storage, general-purpose registers, and floating-
point registers. (See "Manual Store/Display Operations.")
STORE
Stores information into main storage or registers. (See
"Manual Store/Display Operations.")
Resets CPU circuitry. Turns on the IMPL REOD indicator
and executes system reset and resident diagnostic micro-
programs to check CPU hardware.
SYSTEM RESET
Any error detected by system reset turns on the DI AGNOSTIC
STOP indicator. A successful system reset turns off the
I MPL REOD Indicator and tho system Is In a soft-stop awaiting
operator action.
Stores the contents of the current PSW in locations 8-15 and
RESTART
loads the doubleword starting at address 0 as the current PSW.
The channels are not reset and processing starts under control
of the PSW.
START
With the rotary switches in the normal or PROCESS positions,
the START key initiates CPU processing.
Soft stops the CPU when the current instruction and pending
STOP
interrupts are completed. The instruction counter is displayed
in the A-register display indicators while the CPU is in the
soft-stopped state.
INTERRUPT
Requests an external interrupt. The interrupt is taken if
programmed and allowed by the system mask.
LOAD Starts an I nitial Program Load (I pL) operation.
POWER ON I nitiates a power-on sequence.
POWER OFF I nitiates a power-off sequence.
Console Indicators, Switches, and Keys 23