Function Performed on
1 CPU on Which Key
Key Activated Was Activated
System-reset-normal
key without store-Initial CPU reset
status facility with store- CPU reset
status facility Other CPUs in Config CPU reset
Remainder of Configuration Subsystem reset
Subsystem reset
System-reset-clear Clear reset
2
key Clear reset
2 Clear reset
J
Load-normal key Initial CPU reset, CPU reset
followed by IPL Subsystem reset
Load-clear key Clear reset
2
,
followed by IPL Clear reset
2 Clear reset
J
Explanation: * This situation cannot occur, since the store-status facility is
provided in a CPU equipped for multiprocessing.
1 Activation of a system-reset or load key may change the config­
uration, including the connection with I/O, storage units, and
other CPUs. 2 Only the CPU elements of this reset apply. J Only the non-CPU elements of this reset apply.
Manual Initiation of Resets Chapter 4. Control 4-31
Reset Function Sub- Initial Initial Power- system CPU Program CPU Program Clear On Area Affected Reset Reset Reset Reset Reset Reset Reset CPU U S S S1 S S1 S PSW2 U U/V U/V C*l c* C*l C* Prefix U U/V U/V C C C C CPU timer U U/V U/V C C C C
Clock comparator U U/V U/V C C C C
Control registers U U/V U/V I I I I
General registers U U/V U/V U/V U/V C/V C/X
Floating-point registers U U/V U/V U/V U/V C/V C/X
Vector-facility registers U U/V U/V U/V U/V C C
storage keys U U U U U C C/X
3
Volatile main storage U U U U U C C/X
3
Nonvolatile main storage U U U U U C U
Expanded storage U4 U4 U4 U4 U4 U
4
C3 TOO clock US US US US US US T3
Channel-set connection I U U U U
I 1
6
Floating interruption C U U U
U C C3 conditions
Channels in the config-RA U RC U RC RA RAJ uration
Explanation: * Clearing the contents of the PSW to zero places the CPU in the BC mode.
When the IPL sequence follows the reset function on that CPU, the CPU does
not necessarily enter the stopped state, and the PSW is not necessarily
cleared to zeros.
2 3 4 5 6 C
For aBC-mode PSW, the ILC and interruption-code fields are unpredictable
in the current PSW. When these units are separately powered, the action is performed only when
the power for the unit is turned on.
Access to change expanded storage at the time a reset function is performed
may cause the contents of the 4K-byte block in expanded storage to be unpre­
dictable. Access to examine expanded storage does not affect the contents
of the expanded storage.
Access to the TOO clock by means of STORE CLOCK at the time a reset function is performed does not cause the value of the TOO clock to be affected.
When these units are separately powered, the action is model-dependent.
The condition or contents are cleared. If the area affected is a field, the
contents are set to zeros with valid checking-block code.
C/V The checking-block code of the contents is made valid. The contents normally
are set to zeros but in some models may be left unchanged.
C/X The checking-block code of the contents is made valid. The contents normally
are set to zeros but in some models may be left unpredictable.
I The state or contents are initialized. If the area affected is a field, the
contents are set to the initial value with valid checking-block code. Summary of Reset Actions (Part 1 of 2)
4-32 System/370 Principles of Operation
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