Status-Switching ................................................................... .
Program States ....................................................................... .
Problem State .............................. , ..................... , ................ .
Wait State ......................................................................... .
Masked States ....................................... .. Stopped State ...... .. ................................................. . Storage Protection ................................................................ .
Area Identification ................................................ .
Protection Action . . . . . . . . . . . . ... . . . . . . . . . . . .. '" .................. .
Locations Protected ...................... .
Program Status Word ............. .. ................ .
Multisystem Operation ....................................................... ..
Direct Address Relocation .............................. .
Malfunction Indication .................................................. .. System Initialization ........................................................ .
Instruction Format ...................... , .......................................... .
Instructions .......... , . ... . .................................................... .
Load PS"V ............................ " , ................. . Set Program Mask .... .. .......................................... .. Set System Mask . .. .......................................... ..
Supervisor Call ........................................... _ ...................... . Set Storage Key ................................................................ .
Insert Storage Key ............................................. .
Write Direct ........................... , ............ .
Read Direct . .. ................ . ................................................. .
Diagnose ............................................................................ . Status-Switching Exceptions ...................... . Interruptions ................................. .
Interruption Action ...................... .
Instruction Execution .............. " ..................................... . Source Identification ........................................ .
Location Determination ........................ .
Input/Output Interruption .
Program Interruption ...... ............ .. .................. .. Operation Exception ...... _........... .. .................. ..
Privileged-Operation Exception ... _ .......... _ Execute Exception . .. .............................. .
Protection Exception ......................... ..
Addressing Exception ...................... _ ...... _ ................ . Specifica tion Exception ............................................. .
Data Exception .............................................................. .
Fixed-Point-Overflow Exception . _ ..................... .
Fixed-Po:int-Divide Exception ..................... .
Decimal-Overflow Exception ...................... .
Decimal-Divide Exception
Exponent-Overflow Exception
Exponent-Underflow Exception ...................... .. Significance Exception . ....... ..... .. ............ ..
Floating-Point-Divide Exception ............... .
Supervisor-Call Interruption .... . ............................... .
External Interruption ......................... . ............................... .
Timer ...................................................................... .
Interrupt Key .................... .. .................... ..
External Signal ...................................................... .
Priority of Interruptions
Interruption Exceptions ...................................................... . Input/Output Operations .............. ..
Attachment of Input/Output Devices
Input/Output Devices .... .. .............. . Control Units ........................................................ . Channels ... . ......................................................... . System Operation ....... .. ............ .
Compatibility of Operation ............. .. ....................... .. Control of Input/Output Devices .... .
Input/Output Device Addressing ................... .
Instruction Exception Handling ..... . States of the Input/Output System Resetting of the Input/Output System Condition Code ...................................... .
Instruction Format. .. ............ .
Instructions .. .. .. .. .. .. .. .. . .. ............ .. .............. .
Test VO .................. ..
Halt VO ..... .................. .. ......................... ..
Test Channel ..................................... .
Execution of Input/Output Operations ................ .
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96 w Channel Command Word ................................................. . Command Code ................................................................. . Definition of Storage Area ................................................. . Chaining .. .. .......................................................... . Skipping ........................................................................... .
Program-Controlled Interruption ..................................... . Commands ................................................................... .
Termination of Input/Output Operations ................ .
Types of Termination ..................................................... .
Input/Output Interruptions ............................................. . Channel Status Word ....................................................... . Unit Status Conditions .................................................... .. Channel Status Conditions .............................................. . Content of Channel Status Word .................................... ..
System Control Panel ............................ ....................... .
System Control Functions .................................................. . System Reset ..................................................................... . Store and Display ............................................................... .
Initial Program Loading ................................................. .
Operator Control Section ........ .. .................... .
Emergency Pull Switch ................................................... . Power-On Key ............................................................ . Power-Off Key ........ . ........................................ .
Interrupt Key ............................................................. .
Wait Light ................................................. .
Manual Light .............................................................. . System Light .................................................................... .
Test Light ............................................................. .
Load Light .......................................................... .
Load-Unit Switches ............................................ .
Load Key ....................................... .
Prefix-Select Key Switch .................... .
Operator Intervention Section ...................... .
System-Reset Key ................................................. .. Stop Key ........................................................ .
Rate Switch .................. . ....................................... . Start Key............... .. ....................................... . Storage-Select Switch ................................................... .
Address Switches ..................................................... .
Data Switches ............................................................ . Store Key .............................................................. .
Display Key .................................................................... . Set IC Key .................................................................... .
Address-Compare Switches .................................. .
Alternate-Prefix Light .......................................... .. Customer Engineering Section ............................................. .
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Appendix ..... ...................... ............................................... 122
A. Instruction Use Examples .. ............................................ 122
Assembly Language Examples ... .................................... 128
B. Fixed-Point and Two's Complement Notation ........... 132 C. Floating-Point Arithmetic ................................................. 133
D. Powers of Two Table ......... .. .............................. 135
E. Hexadecimal-Decimal Conversion Table ...... 136
F. EBCDIC and ASCII (Extended) Charts ...................... 141
C. Instructions . .................. .. .. ...................... .......... 142
Data Formats 142
Hexadecimal Representation ........ ........................ 142
Instructions by Format Type ................ 142 Control Word Formats .................................... 144 Operation Codes ........ .... ........... .. ............................. 145
Permanent Storage Assignment .. ........................... 147
Condition Code Setting .... ....................... 147
Interruption Action ... ... ...................... 148
Instruction Length Recording .................. 148
Program Interruptions ... . ..................... 148
Editing ..... . ....... ................. ........ . 153 System Control Panel ......... ................................ 153
Input/Output Operations ... ........... ............. .................. 153
Time and Method of Creating and Storing Status Indications .. '" ........ . ..................................................... 155
Functions That May Differ Among Models ........... ........ 156
Alphabetic List of Instructions .. .............. ....... 159
List of Instructions by Set and Feature ...... 160 Index of Instruction Formats by Mnemonic 162

The IBM System/360 is a solid-state, program com­
patible, data processing system providing the speed,
precision, and data manipulating versatility demand­
ed by the challenge of commerce, science, and in­
dustry. System/360, with advanced logical design im­
plemented by microminiature technology, provides a
new dimension of performance, flexibility, and relia­
bility. This dimension makes possible a new, more
efficient systems approach to all areas of information
processing, with economy of implementation and ease
of use. System/360 is a single, coordinated set of new
data processing components intended to replace the
old logical structure with an advanced creative de­
sign for present and future application.
The logical design of System/360 permits efficient
use at several levels of performance with the preser­
vation of upward and downward program compati­
bility. Extremely high performance and reliability re­
quirements are met by combining several models into
one multisystem using the multisystem feature.
General-Purpose Design System/360 is a general-purpose system designed to
be tailored for commercial, scientific, communications,
or control applications. A Standard instruction set pro­
vides the basic computing function of the system .. To
this set a decimal feature may be added to provide a
Commercial instruction set or a floating-point feature
may be added to provide a Scientific instruction set.
When the storage protection feature is added to the
commercial and scientific features, a Universal set is
obtained. Direct control and timer features may be
added to satisfy requirements for TELE-PROCESSINC@ systems to allow load-sharing or to satisfy real-time
needs. System/360 can accommodate large quantities of
addressable storage. The markedly increased capaci­
ties over other present storage is provided by the
combined use of high-speed storage of medium size
and large-capacity storage of medium speed. Thus,
the requirements for both performance and size are
satisfied in one system by incorporating a heirarchy
of storage units. The design also anticipates future
development of even greater storage capacities. Sys­ tem/360 incorporates a standard method for attaching
input/output devices differing in function, data rate, IBM System/360
and access time. An individual System/360 is obtained
by selecting the system components most suited to the
applications from a wide variety of alternatives in in­
ternal performance, functional ability, and input/out­
put (I/O). Models of System/360 differ in storage speed, width
(the amount of data obtained in each instruction ac­
cess), register width, and capability of simultaneous
processing. Yet these differences do not affect the logi­
cal appearance of System/360 to the programmer. Several cpu's permit a wide choice in internal per­
formance. The range is such that the ratio of internal
performances between the largest and the smallest
model is approximately 50 for scientific computation
and 15 for commercial processing.
Compatibility
All models of System/360 are upward and downward
program compatible, that is, any program gives identi­
cal results on any model. Compatibility allows for
ease in systems growth, convenience in systems back­
up, and simplicity in education.
The compatibility rule has three limitations.
1. The systems facilities used by a program should
be the same in each case. Thus, the optional CPU fea­
tures and the storage capacity, as well as the quantity,
type, and priority of I/O equipment, should be equiva­
lent.
2. The program should be independent of the re­
lation of instruction execution times and of I/O data
rates, access times, and command execution times.
3. The compatibility rule does not apply to detail
functions for which neither frequency of occurrence
nor usefulness of result warrants identical action in
all models. These functions, all explicitly identified in
this manual, are concerned with the handling of in­
valid programs and machine malfunctions.
System Program
Interplay of equipment and program is an essential
consideration in System/360. The system is designed
to operate with a supervisory program that coordi­
nates and executes all I/O instructions, handles excep­
tional conditions, and supervises scheduling and exe­
cution of multiple programs. System/360 provides for
IBM System/360 5