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File No. S360-01
Order No. GA24-3231-7




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IBM System/3S0 Model 30 Functional Characteristics

This reference publication describes the relationship
of the IBM System/360 Model 30 to the entire
System/360, The system's capabilities, features, I/O
channels, and operations are also discussed.
The reader can find a more detailed description of
System/360 operations in IBM System/360 Principles
of Operation, GA22-6821. The interrelationships of
the models and units available with System/360
are broadly described in IBM System/360 System
Summary, GA22-6810. Other related literature is
referenced by order number and briefly described in
IBM System/360 Bibliography, GA22-6822.
Information on channel load limits for IBM System/360
Model 30 is given in IBM System/360 Model 30
Channel Characteristics and Functional Evaluation,
GA24-3411. System-console operating procedures
are contained in IBM System/360 Model 30
Operating Guide, GA24-3373.
Preface




The first section of this manual-IBM System/360
l\,f ode130, General Concepts-presents a general intro-
duction to some important IBM System/360 concepts
and terminology. Throughout most of this section, con-
cepts such as program status words, supervisor pro-
gram, and interrupts are related to input/output oper-
ations. The object of this section is to present certain
system operations, referenced to IBM System/360
Model 30, without taking into account all possible
variations and exceptions that may apply. Subsequent
sections of this publication provide more detailed in-
formation.
IBM System/360 Model 30 has a storage cycle time
of 1.5 microseconds. Early systems, however, have a
2-microsecond storage cycle time. In this publication,
timings that pertain to the 2-microsecond Central
Processing Unit (cpu) are shown in parentheses fol-
lowing the timings given for the 1.5-microsecond CI1U.
For example:
The RCW (read/compute/write) cycle requires 2.25
microseconds (for 2-microsecond CPU: 3 microsec-
onds).




Eighth Editioll (August 1971)

This is a reprint of GA24-3231-6 incorporating changes released in Technical
Newsletter, GN24-047S, dated July 19, 1971. Changes are periodically made
to the specifications herein: before using this publication in connection with
the operation of IBM systems, refer to the latest SRL Newsletter, GN20-0360,
for the editions that are applicable and current.
Requests for copies of IBM publications should be made to your IBM
representative or to the IBM branch office serving your locality.
This manual has been prepared by the IBM Systems Development Division,
Product Publications, Dept. K10, P.O. Box 6, Endicott, N.Y. 13760. A
form has been provided at the back of this publication for reader's comments.
Contents




Preface... . . . ..... ..... ..... .... ................. 2 IBM 1050 Lights, Switches, and Functional Keys . .. 47

IBM System/360 Model 30, Functional Commands Initiated by Start I/O . . . . . . . . . . . . . . . .. 52
Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Read Inquiry Command. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 52
General Concepts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Read Reader-2 Command. . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
Data Processing System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Write Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54
IBM System/360 Model 30 Input/Output Control. . . . . . . . 6 Sense Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 54
Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 No Op Command ............................... '.... 55

Home Component Recognition ............... , . . .. 56
IBM System/360 Model 30, Characteristics. . . . . . . . 9 Write Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 56
IBM 2030 Processing Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Read Inquiry Comma.nd. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 56
IBM 2030 Processing Unit Special Features. . . . . . . . . . . .. 10 Read Reader-2 Command. . . . . . . . . . . . . . . . . . . . . . . . . . .. 56
Off-Line 1050 Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . .. 57
IBM System/360 Model 30, General Organization 13 IBM 1050 I/O Prefix Selection. . . . . . . . . . . . . . . . . . . . . . .. 57

Input/Output Devices. . . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Miscellaneous Operations. . . . . . . . . . . . . . . . . . . . . . .. 58
Write to Card Punch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 58
Operations Terminated by Intervention Required. . . . . . .. 58
Input/Output Channels. . . . . . . . . . . . . . . . . . . . . . . . .. 17 Test I/O.. ........ .... ............ . ..... ..... . .... 58
Channel Restrictions on the Model 30 ... , ............ " 17 Halt I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 58
Multiplexor Channel .................. , . . . . . . . . . . . .. 18
Selector Channels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , " 23
Channel Loading and Interaction. . . . . , , . . . . . . , . . . . . . .. 24 Condition Code Settings for 1050
Documentary Console . . . . .. . . . . . . . . . . . . . . . . . .. 59
Model 30 CPU Timings and Priorities, . . . . . . . . . . . .. 25
Instruction Timing Information. . . . . . . . . , . . . , . . . . . . . " 25 Codes (1050) ..... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 61
Interval Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
I/O Interruption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
Other Program Interruptions ........ , . . . . . . . . . . . . . . . .. 29 Extended Binary Coded Decimal Interchange Code
Diagnose Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33 (EBCDIC). , ..... , ............ , . . . . . . . . . . . . . . . . . . .. 63
Diagnostic Scan-Out Area. . . . . . . . . . . , . . . . . . . . . . . . . . .. 33
Appendix A, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 65
IBM 2030 System Control Panel. . . . . . . . . . . . . . . . . .. 35 Typical Model 30 Algorithms. , ....... ' ............. " 65
Pages 35 through 43 in this publication are obsolete and have
been replaced by IBM System/360 Model 30 Operating GUide Appendix B (Auxiliary Storage) ................. " 67
GA24-3373. ' Local Storage and MPX {Multiplexor} Storage Map. . . . .. 67

Appendix C
Extended BCD Interchange Code ........... , ........ . 70
IBM 1050 Documentary Console ................. . 44
Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . 44 Index ........... , ..... , 72
Figure 1. IBM 2030 Processing Unit with IBM] 1050 Documentary Console Control
IBM System/360 Model 30, Functional Characteristics




Data processing systems provide rapid methods of proc- A variety of input/output devices can be attached
essing the varied types of information used in today's to this system. "As data processing needs increase, stor-
commercial and scientific communities. Significant in- age capacity can be enlarged, and additional input/out-
creases in the operating efficiency of many businesses put devices can be attached. Modification of programs
have resulted from use of data processing systems. used on IBM System/360 is made easier because the
As the information-handling requirements of a busi- instructions used for the smaller storage and I/O con-
ness grow, expansion of data processing facilities be- figurations apply to the larger-capacity configurations.
comes more and more desirable. As the advantages For example, programs used on different models of
of a data processing system become evident (through IBM System/360 can be run on an IBM System/360
use in initial applications), users apply "this powerful Model 30 (within the limitations set forth in IBM Sys-
tool to other areas of their business. Expansion of tem/360 Principles of Operation, Form A22-6821).
present operations and extension to new application
areas are made easier when:
Data Processing System
l. Methods of directing the system (programming) Let's consider the over-all operation of a data process-
are modified rather than completely reworked. ing system. The basic configuration of a data process-
ing system is shown in Figure 2.
2. Input/Output devices required in new applications
can be connected to present eqtiipment. A program-series of instnlCtions that control sys-
tem operations-is contained in a storage area, which
3. Storage capacity can be increased without the need is usually in the central processing unit. The program
for ordering an entirely new central processing unit. is usually written in the following manner:

l. The job to be run is fully defined.
4. Various input!output and communications devices
Some typical questions that must be answered are:
that can be attached to the system are available.
vVhat types of results are required?
What input/output devices are needed?
These advantages are all offered in IBM System/360. What exceptional conditions can occur?
Modest requirements can be met through use of an
IB~f System/360 Model 30 with 8,192 bytes of main
2. A pictorial block diagram (flow chart) is constructed
storage. to represent the job to be performed.
Note: A !Jute is a position of storage in which eight bits of in-
formation can be stored, stich as an alphabetic character, or 3. The programmer then writes detailed instructions
two numeric characters. in symbolic form. Note that the system performs




Input Output
Device Device

Processing
Unit
Input Output
Device Device


Figure 2. Basic Data Processing System

5
operations under control of machine language in- There are two types of channels: Selector and multi-
structions. For the programmer, however, machine plexor. One distinguishing feature of a selector chan-
language instructions are more difficult to write nel (special feature on Model 30) is that it is used to
than are symbolic instructions. Programs written sustain operation of one device at a time. A variety of
in symbolic form are also much more easily modi- devices can be attached to a selector channel, but it is
fied than are aetual machine language programs. most useful when used with high-speed I/O devices.
For example, the high-speed transfer of information
4. An assembly program, provided by IBM, is loaded from a magnetic disk storage device to the CPU can
into the system through an input device -(such as a be advantageously handled by a selector channel.
card reader). The symbolic program is then loaded The data-handling capability of the multiplexor
in a similar manner. The assembly program trans- channel is normally lower than that of the selector
forms the symbolic instructions into machine lan- channel, although the multiplexor channel on Model
guage, producing an object program that is used in 30 can presently handle the same data rates of I/O
the actual job runs. devices attached to the selector channel (due to fast-
est I/O device presently attachable-170 kc). The ad-
Once the object program is produced and loaded vantage of the multiplexor channel is that it ca~ service
into storage, information (source data) that is related the data flow and control requirements of several slow-
to the job (such as payroll data) can be entered in"to speed I/O devices at a time. This kind of operation is
the system, and the job can be run. The source data accomplished in multiplex mode (sometimes called
is entered into an input device (Figtlre 2). An instruc- data interleaved mode). For example, the data sent
tion in the program directs that this information be from two serial card readers to the CPU can be han-
sent from the input device to the processing unit. The dled at one time in multiplex mode by the multiplexor
data is processed. That is, operations such as logical channel.
decisions and arithmetic functions are performed. Re- The selector channel is usually used for high-speed
sult data is then sent to one or mQre output devices data rate I/O devices because selector-channel data
where meaningful records (printed reports, punched transfer operations overlap CPU operations while CPU
cards, etc.) are produced. This phase of the operation facilities are used for multiplexor-channel data transfer
is also under control of the program. operations.
In System/360, input/output devices are controlled
by control units (as shown in Figure 2).
Interruptions and I/O Control

To allow for the coordination of overlapped 1/0 opera-
tions and provide for a smooth flow of productive
IBM System/360 Model 30 Input/Output
processing, it is necessary to provide a .means of switch-
Control
ing from one program to another. In the System/360,
Let's consider, in a general way, how IBM System/360 an interrupt system is prOVided for this purpose.
Model 30 controls the input/output (110) functions An interrupt causes a program to be suspended and
already described. A standard I/O interface is pro- allows some alternate operation to be started.
vidcd for the attachment of a wide variety of I/O Let's follow the progress of a typical 1/0 operation
devices to System/360. Thc interface is a standard set as it occurs in the IB?,,! System/360. Assume that in-
of elcctrical conncctions through which signals arc structions are being executed in thc problem program
sent that allow for exchange of data