Initial Program Load; Ipl Error Recovery; Power On; Power Off - IBM System/370 145 Operating Procedures Manual

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INITIAL PROGRAM LOAD (IPL)
1. Load and ready the I PL device.
2. Dial the address of the I PL device into LOAD UN IT
switches F, G and H.
3. Press the LOAD key.
• The system reset routine is performed and the I PL
operation is started.
• The LOAD indicator turns on.
• When IPL is complete, the LOAD indicator is turned
off and the system either executes the program or
enters the soft-stop state awaiting operator action.
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IPL ERROR RECOVERY
Load Unit Switches Correct?
IPL Device Ready?
If setup is correct and IPL errors still occur, IPL using a
different device and a backup tape or disk. If errors per-
sist, call your service representative.
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POWER ON
The POWER-ON key, when pressed, initiates a power-on
sequence for the CPU and on-line I/O units. The key
turns red when pressed and white when the power-on
sequence is complete. The time required for a power-on
sequence is determined by the number and type of I/O
units on-line. Storage is not valid after a power-on
sequence: an IMPL operation is required_ (The IMPL
is automatic if the rotary switches are in their normal
processing positions, the ADDRESS COMPARE CON-
TROL switch is in the SYNC/NORM position, and the
IMPL disk is mounted on the console file.)
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POWER OFF
ThePOWER-OFF key, when pressed, removes power to
the CPU and on-line I/O units. Main and control storage
information is lost. Recommended power-off procedure:
1. Press the CPU STOP key.
2. Press the POWER-OFF key.
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POWER FAILURE RECOVERY
If a power supply failure or overtemperature condition
occurs while the system is operating, a power-off sequence
is initiated and the POWER-OFF key lights red to indicate
the failure.
1.
Press the POWER-OFF key (resets the indication and
allows the POWER-ON key to be operative).
2. Press the POWER-ON key.
If the condition causing the failure was temporary,
power will come up normally.
If power cannot be restored, call your service representa-
tive.
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EMERGENCY PULL SWITCH (EPO)
The EMERGENCY PULL switch, when pressed, turns off
electrical power to the CPU and on-line I/O units and
makes the POWER-ON key ineffective until the EMER-
GENCY PULL switch is reset by your service representa-
tive. The contents of main and control storage are invalid
if this switch is operated.
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INSTRUCTION STEP
1. Press the STOP key.
2. Set the RATE switch to the INSTRUCTION STEP
position.
3. Press the START key.
One machine language instruction is executed for each
operation of the START key. The instruction counter is
displayed in the A-REGISTER DISPLAY roller switch indi-
cators and contains the address of the next instruction to
be executed.
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SET IC (INSTRUCTION COUNTER)
1. Press the STOP key.
2. Dial the desired address into console switches CDEFGH.
3. Press the SET I C key.
The set instruction counter operation loads the address
from switches CDEFGH into the instruction counter.
I nstruction processing starts from this address when the
START key is pressed.
Operating Procedures 39