Contents DIAGNOSE. . INSERT PSW KEY INSERT STORAGE KEY LOAD CONTROL . . LOAD PSW . . LOAD REAL ADDRESS PURGE TLB.
READ DIRECT. . . RESET REFERENCE BIT. SET CLOCK. . . . SET CLOCK COMPARATOR. SET CPU TIMER . . . . SET PREFIX SET PSW KEY FROM ADDRESS. SET STORAGE KEY . SET SYSTEM MASK . . SIGNAL PROCESSOR. . STORE CLOCK COMPARATOR. STORE CONTROL. . STORE CPU ADDRESS STOR E CPU ID. . STORE CPU TIMER STORE PREFIX. STORE THEN AND SYSTEM MASK STORE THEN OR SYSTEM MASK WRITE DIRECT The system-control instructions include all privileged
instructions that are described in this manual except
the input/ output instructions, which are described in
the chapter "Input/Output Operations."
The system-control instructions and their mne­
monics, formats, and operation codes are listed in
the following table. The table also indicates when
the condition code is set and the exceptional condi­
tions in operand designations, data, or results that
cause a program interruption.
Note: In the detailed descriptions of the individual
instructions, the mnemonic and the symbolic oper­
and designation for the IBM System/370 assembly
language are shown with each instruction. For LOAD PSW, for example, LPSW is the mnemonic
and D2(B2) the operand aesignation.
Diagnose
83
o 8 31
The CPU performs built-in diagnostic functions, or
other model-dependent functions. The purpose of
the diagnostic functions is to verify proper function-
System-Control Instructions 103 104 105 105 105 106 107 107 107 108 108 109 109 109 110 110 110 111
111
112
112
113
113
113
114
114
ing of CPU equipment and to locate faulty compo­
nents. Other model-dependent functions may in­
clude disabling of failing buffers, reconfiguration of
storage and channels, and modification of control
storage.
Bits 8-31 may be used as in the SI or RS formats,
or in some other way, to specify the particular diag­
nostic function. The use depends on the model.
The execution of the instruction may affect the
state of the CPU and the contents of a register or
storage location, as well as the progress of an I/O operation. Some diagnostic functions cause the test
light of the system console to be turned on.
Condition Code: The code is unpredictable.
Program Exceptions:
Privileged Operation
Depending on the model, other exceptions may be
recognized.
Programming Notes
Since the instruction is not intended for problem­
program or supervisor-program use, DIAGNOSE
has no mnemonic.
DIAGNOSE, unlike other instructions, does not
System-Control Instructions 103

Name Mnemonic Characteristics Code DIAGNOSE M DM 83 INSERT PSW KEY IPK S PK M R 8208 INSERT STORAGE KEY ISK RR M A1 SP R 09 LoAD CONTROL LCTL RS M A SP 87
LOAD PSW LPSW S L M A SP $ 82
LOAD REAL ADDRESS LRA RX C
TR M A2 R
81
PURGE TIL8 PTL8 S TR M $ 820D READ DIHECT RDD SI DC M A $ ST 85
RESET RI:FERENCE BIT RR8 S C
TR M A1 8213
SET CLOCK SCK S C
M A SP 8204 SET CLOCK COMPARATOR SCKC S CK M A SP 8206 SET CPU TIMER SPT S CK M A SP 8208 SET PREFIX SPX S MP M A SP $ 8210 SET PSW IKEY FROM ADDRESS SPKA S PK M 820A SET STOnAGE KEY SSK RR M A1 SP 08 SET SYSTEM MASK SSM S M A SO 80 SIGNAL PROCESSOR SIGP RS C
MP M $ R
AE STORE CLOCK COMPARATOR STCKC S CK M A SP ST 8207 STORE CONTROL STCTL RS M A SP ST 86 STORE CPU ADDRESS STAP S MP M A SP ST 8212 STORE CPU ID STIDP S M A SP ST 8202 STORE CPU TIMER STPT S CK M A SP ST 8209 STORE PHEFIX STPX S MP M A SP ST 8211 STORE TI-IEN AND SYSTEM MASK STNSM SI TR M A ST AC
STORE THEN OR SYSTEM MASK STOSM SI TR M A ST AD WRITE DIRECT WRD SI DC M A $ 84 Explanation: A exceptions PK PSW-key-handling feature
A1 exceptions only R PER general-register-alteration event
A2 and translation-specification exceptions only RR RR instruction format
C
Condition code is set RS RS instruction format
CK CPU-ti mer and clock-comparator feature RX RX instruction format
DC Direct-control feature S S instruction format
DM Depending on the model, DIAGNOSE may generate SI SI instruction format
various program exceptions and may change the SO Special-operation exception
condition code. SP Specification exception
L New Icondition code loaded ST PER storage-alteration event
M Privil,eged-operation exception TR Translation feature
MP Multiprocessing feature $ Causes serialization
System-Control-Instruction Summary follow the rule that programming errors are distin-Insert PSW Key
guished from equipment errors. Improper use of DIAGNOSE may result in false indi- IPK [S] cations or may cause actual machine malfunctions to
be ignored. It may also alter other aspects of system 8208 operation, including instruction execution and chan- 0 16 31
nel operation, to an extent that the operation does
not comply with that specified in this manual. As a The four-bit protection key of the current PSW is
result of the improper use of DIAGNOSE, the sys-inserted into bit positions 24-27 of general register
tern may be left in such a condition that the power-2. Bits 0-23 of general register 2 remain unchanged,
on reset or initial-microprogram-Ioading function and bits 28-31 are set to zeros. Bits 16-31 of the
must be performed. instruction are ignored. 104 System/370 Principles of Operation