Use this system macro to change the operating state of the central
processing unit (CPU) from problem to supervisor state with key 0 set and the
input/output (I/O) interrupts masked. This macro provides a
mechanism for returning the first part of the program status word (PSW) active
at the time of its invocation to the calling program.
Supervisor state allows processing of privileged instructions. See
the MONTC-Set Supervisor State (Monitor Mode) macro for an E-type method of setting supervisor
state.
Format
- label
- A symbolic name can be assigned to the macro statement.
- OLDSTATE=Rx
- An optional parameter specifying a register to receive the first word of
the PSW active at the time of $MONTC processing.
Entry Requirements
This macro is for use in the control program (CP) only.
Return Conditions
- Control is returned to the next sequential instruction.
- The TPF system is masked for I/O interrupts.
- The contents of all registers are preserved across this macro call except
for the register specified by the OLDSTATE parameter.
- The CPU is in supervisor state (PSW bit 15 = 0).
- The storage protect key is zero (PSW bits 8 - 11).
Programming Considerations
- This macro can be run on any I-stream.
- This macro is for system programming use only.
- Care should be exercised when operating in this state. Any location
in main storage can be modified, except that to modify locations below the
512-byte line the LCPCC macro should be used first.
- Supervisor state is maintained across all other macros that can be issued
by the program.
Examples
None.