IBM 4381 User manual

Systems
GC20-2021-2
File No. 4300
A Guide to the IBM 4381
Processor
This guide presents hardware, 1/0 device, programming
systems, and other pertinent information describing the
significant new features and advantages
of the IBM 4381
Processor. Knowledge of System/370 or 4300 hardware
and 1/0 devices is assumed. The content of the guide is
intended to acquaint the reader with the 4381 Processor
and
to be of benefit in planning for its installation.
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Third Edition (April 1986)
This edition is a major revision obsoleting GC20-2021-l. It discusses 4381 Processor
Model Groups 11, 12, 13, and 14. New and changed information
is indicated by a vertical
rule in the left margin.
This guide
is intended for planning purposes only. It will be updated from time to time;
however, the readers should remember that the authoritative sources of system
information are the system library publications for the 4381 Processor, its associated
components and its programming support. These publications will first reflect any
changes.
References in this publication to IBM products, programs, or services do not imply that
IBM intends to make these available in all countries in which IBM operates.
Publications are
not stocked at the address given below. Requests for copies of IBM
publications should be made to your IBM representative or to the IBM branch office
servicing your locality.
A form for readers' comments has been provided at the back of this publication.
If the
form has been removed, address comments to: IBM Corporation, Department 824, 1133
Westchester Avenue, White Plains, New York 10604. IBM may use or distribute
whatever information you supply in any way it believes appropriate without incurring any
obligation to you.
© Copyright International Business Machines Corporation 1984, 1985, 1986

Preface
This publication is designed for readers who are knowledgeable about System/370
architecture (as implemented in a System/370 or 4300 processor), and
4300/System/370 channels, 1/0 devices, and programming systems. Features of
4381 Processor model groups that are like the same features in 4341 Processors are
identified, and only those hardware and programming systems features of 4381
Processors that are different from those of 4341 Processors are described in detail.
Compatibility among the architectures implemented in 4381, other 4300, and
System/370 processors and their programming systems support
is also discussed.
Information about the currently available 4381 model groups (11, 12, 13, and 14)
and the withdrawn model groups (
1, 2, and 3) is given in this guide.
Preface iii

iv A Guide to the IBM 4381 Processor

Contents
Section 01 : Highlights 1
Section 10: Technology and Architecture 14
10:05 Technology 14
Introduction 14
Logic Chip, Module, and Board Design
15
Logic Cooling 19
Storage Technology
21
10:10 Architecture 21
System/370 Architecture 21
System/370 Extended Architecture 23
Section 20: 4381 Processor Uniprocessor Model Groups 27
20:05 Instruction Processing Function
28
General Description 28
Instruction Set 30
Multiply and Add Facility 32
Elementary Math Library Facility 32
Square Root Facility and Mathematical Function Facility 32
ECPS:MVS 33
ECPS:VM/370 34
Preferred Machine Assist 34
20: 10 Storage 34
Processor Storage 35
Auxiliary Storage 37
Storage Control Function 39
20:
15 Support Processor Subsystem 42
Components and Functions 42
System Diskette Drives 44
System Initialization 45
Natively Attached Devices 46
Support Bus Adapter 46
20:20 Channels 47
General Description 47
Device Addresses and Unit Control Words
For System/370 Mode 48
Subchannels
For System/370-XA Mode 50
General Operation of the Channels 52
Byte Multiplexer Channels 54
Block Multiplexer Channels 55
SIOF Instruction
For System/370 Mode 57
20:25 Standard and Optional Features 58
Standard Features 58
Optional Features 60
Contents V

Section 30: 4381 Processor Multiprocessor Model Groups 61
30:05 Configuration Description 61
30:10 Instruction Processing Function 63
General Description 63
Instruction Set 65
Other Features 66
30:15 Storage 66
Processor Storage 66
Auxiliary Storage
68
Storage Control Function 70
30:20 Support Processor Subsystem 74
Components and Functions 74
30:25 Channels 74
General Description 74
Device Addresses and Unit Control Words For System/370 Mode 76
Subchannels For System/370-XA Mode
78
General Operation of the Channels 78
Byte Multiplexer Channels 79
Block Multiplexer Channels 79
SIOF Instruction For System/370 Mode 80
30:30 Standard and Optional Features
81
Standard Features 81
Optional Features 83
Section 40: Operator Console 84
40:05 General Description 84
Operator/Operating System Communication Modes
85
Operator Control Panel 86
Keyboard 88
System Configuration Displays 89
40:10 Operator Displays 90
General Selection Display 90
40:15 Remote Operator Console Facility (ROCF)
91
40:20 Maintenance 93
Section ~O: Virtual Storage and Address Translation 94
Virtual Storage Organization 94
Address Translation
95
Section 60: Reliability, Availability, and Serviceability (RAS) 97
60:05 Introduction 97
60:10 Recovery Features 98
Automatic Instruction Retry 98
ECC Validity Checking On Processor Storage 99
1/0Operation Retry 101
Machine Check Facilities 101
Machine Check Analysis and Logging 108
Functional Diskette 1 Logouts 109
Power System 110
60:
15 Diagnostic and Remote Support Facilities 113
Problem Analysis 113
Support Processor Subsystem Diagnostics 115
Power Controller Adapter Diagnostics 116
vi A Guide to the IBM 4381 Processor

Instruction Processing Function Diagnostics 116
Error Logout Analysis Program
11 7
System Test 117
Remote Support Facility 117
Section 70: Programming Systems Support 119
70:05
DOS/VSE 119
70: 10
OS/VSl 120
70:15
MVS/370 120
70:20
VM/370 120
70:25
MVS/XA 121
70:30 VM/Extended Architecture Migration Aid 122
70:35 Virtual Machine/System Product-Entry 123
70:40 Virtual Machine/Extended Architecture Systems Facility 124
70:45 Programming Systems Support Table 125
Section 80: Comparison Table of Hardware -4341 Model Group 12 and 4381
Processors 127
80:05 Hardware Features of the 4341 Model Group 12 Processor and 4381 Model
Group 11, 12, 13, and 14 Processors 128
Index 134
Contents vii

Figures
1. The 4381 Processor and console 12
2. Two 64-mm MCMs 16
3. A 64-mm MCM being hand held 17
4. The 4381 MCM board without any modules mounted
18
5. 64-mm MCMs mounted on the MCM board 18
MCM board mounted within the 4381 Processor
19
6.
7.
8.
9.
64-mm MCM with a portion of the heat sink cut away 20
An impingement cooling nozzle ·20
Logical components in a 4381 Processor Model Group 11, 12, 13,
1, or
2
27
10. General flow of data between the channels and processor storage 53
11. Logical components in a 4381 Processor Model Group 14 or 3 62
12. Data flow to and from processor storage via the high-speed buffers in a 4381
Model Group
14 or 3 71
13. The General Selection display 90
14. Dialup of a remote 4381 Processor via a 3275 display
91
15. Dialup of a remote 4381 Processor via a host processor emulating a 3275
display 92
16. 4381 Processor machine check code 103
17. 4381 Processor machine check interruptions
105
viii A Guide to the IBM 4381 Processor

. ..._....
Section 01: Highlights
The 4381 Processor, available in four model groups, is an intermediate-scale,
general purpose processor that
is compatible with System/370, other 4300, and
30XX processors.
It implements System/370 architecture (as in System/370,
4300, and 30XX processors) and System/370 extended architecture (as in 308X
and 3090 processors).
Model Groups 11, 12, 13, and 14 of the 4381 Processor, which offer a wide range
of performance, are provided. Model Group 11, 12, and
13 4381 Processor units
are uniprocessors containing one instruction execution function. The Model Group
14 4381 Processor unit
is a dual processor that contains two instruction execution
functions each of which has its own channels. The Model Group
14 processor unit
operates
as a tightly coupled multiprocessing configuration under the control of one
operating system in which processor storage
is shared.
Field upgrades of 4381 Processor model groups
is supported. A 4381 Model
Group
11 Processor can be field upgraded to a 4381 Model Group 12 Processor, a
4381 Model Group 12 can be field upgraded to a 4381 Model Group 13, and a
4381 Model Group
13 can be field upgraded to a 4381 Model Group 14. This
support provides significant performance growth. The 4381 Model Group 14 has
an internal throughput rate of up to 4.9 times that of a 4381 Model Group
11 for
commercial processing and of up to 5.4 times that of a 4381 Model Group
11 for
scientific processing.
Model Groups
11through14 of the 4381 Processor offer improved price
performance relative to Model Groups
1, 2, and 3 of the 4381 Processor, which are
withdrawn from marketing,
as are model upgrades within these withdrawn model
groups. However, optional features, including processor storage upgrades, can be
installed in 4381 Model Group
1, 2, and 3 Processors. In addition, these
withdrawn model groups can be field upgraded to the current 4381 model groups
as follows: 4381 Model Group
1toa4381 Model Group 12 or 13, 4381 Model
Group 2 to a 4381 Model Group
13 or 14, and 4381 Model Group 3 to a 4381
Model Group
14.
The 4381 Processors offer higher internal performance and improved price
performance for intermediate system users relative to 4341 Processors. This
improved performance
is made possible by the use of large-scale integrated
technology for logic and processor storage. The logic packaging and cooling
designs implemented in 4381 Processors provide increased logic density without the
need for water cooling.
The
43 81 Processors support the range of commercial and engineering/scientific
data processing capabilities offered by System/370, 4300, and 30XX processors,
as well as the advanced functions provided by System/370 and System/370
extended architectures.
Section 01 : Highlights 1

The 4381 Processor Model Group 11 is a logical growth processor for System/370
processors (such
as Models 135 to 148) and smaller 4341 Processors. Model
Groups 12, 13, and
14 of the 43 81 Processor provide a growth path for users of
larger 4341 Processor model groups, System/370 Models 155 to 168, and 303X
processors.
Relative to 4341 Processors, 4381 Processors offer intermediate system users
increased internal performance and channel performance; improved price
performance; reliability, availability, and serviceability improvements; hardware
and programming systems compatibility; System/370 extended architecture
advantages; and a wide range of operating system support.
The 4381 Processors can be utilized in decentralized and distributed processing
environments that require higher internal performance and more channel capability
than
is provided by 4341 Processors. They can also be used in 30XX installations
to support application offloading.
The 4381 Processors are particularly well suited to handle engineering/scientific
applications, such as
CAD/CAM, graphics, and problem solving. The performance
of floating-point and binary multiply operations in 4381 Processors
is significantly
improved. Standard engineering/scientific assist features can be used to further
improve floating-point arithmetic performance for selected functions.
The 4381 Processors operate with a broad spectrum of IBM products that support
engineering/scientific applications, including the 3251 Display Station and 5080
Graphics System, 3838 Array Processor, 7350 Image Processing System, Series/1
processors, and IBM personal computers. The 4381 Processors can also be used
with the IBM Device Attachment Control Unit and 7171 ASCII Device
Attachment Control Unit to implement engineering/scientific applications that
require the use of non-IBM devices. The IBM 4994 ASCII Device Control Unit
can be channel-attached to 4381 Processors. The 3044 Fiber Optic Channel
Extender Link can be used to extend the distance between terminals/devices and
the 4381 Processor (up to two kilometers) while providing near local terminal
response time.
System/370 extended architecture, which
is implemented in 308X and 3090
processors,
is also implemented in 4381 Processors, which are supported by the
MYS/Extended Architecture (MVS/XA) operating system. Therefore, a 4381
Processor can be used for
MVS/XA testing in a 308X or 3090 installation or as
the entry MVS/XA processor in installations that expect growth to a 308X or
3090 processor and MVS/XA.
The 4381 Processors have extensive operating system support. When operating
with System/370 architecture
in effect (in System/370 mode), 4381 Processors are
supported by the same operating systems
as 4341 Processors operating in
System/370 mode. When operating with System/370 extended architecture in
effect (in System/370 extended architecture mode), 4381 Processors are supported
by the same operating systems
as 308X and 3090 processors operating in
System/370 extended architecture mode.
2 A Guide to the IBM 4381 Processor

Model Groups 11, 12, and 13 of the 4381 Processor operating in System/370
mode are supported by the following IBM-supplied virtual storage programming
systems (which also support 4381 Processor Model Groups 1 and 2):
• Disk Operating System/Virtual Storage Extended (DOS/VSE) with
VSE/ Advanced Functions as of Release 1.3.5 (the VSE System) or
VSE/System Package (VSE/SP)
as of Release 1.3.5
• Operating System/Virtual Storage 1
(OS/VSl) Release 7 with OS/VSl Basic
Programming Extensions Release 4
• Operating System/Virtual Storage 2 Multiple Virtual Storage (OS/VS2 MYS)
Release 3.8 with an MYS/System Product (MYS/SP) Version 1 Release 3.3
or 3.5 program product (MYS/System Product-JES2 or MYS/System
Product-JES3) installed and the appropriate PTF applied. This version of
MYS
is MVS/370 (MYS with MYS/SP Version 1).
• Virtual Machine/370
(VM/370) Release 6 with VM/System Product
(VM/SP) Release 3 or later and without or with
VM/SP High Performance
Option Release 3.2 or later.
VM/SP High Performance Option is required to
support more than l 6Mb of processor storage.
• Virtual Machine/Entry (VM/Entry)
• Airline Control Program/Transaction Processing Facility
(ACP/TPF) Version
2.3
Model Groups 11, 12, and
13 of the 4381 Processor operating in System/370
extended architecture mode are supported by the following (which also support
4381 Processor Model Groups 1 and 2):
• MYS Release 3.8 with MYS/SP (MVS/SP-JES2 or MVS/SP-JES3) Version 2
Releases 1.2 and 1.3 and (with the appropriate PTF applied) and
MVS/XA
Data Facility Product (the MVS/XA operating system)
• Virtual Machine/Extended Architecture
(VM/XA) Migration Aid Release 2
or later
Virtual Machine/Extended Architecture
(VM/XA) Systems Facility Release 1
The 4381 Processor Model Group 14 operating in System/370 mode
is supported
by the following (which also support the 4381 Model Group 3):
• MVS/SP-JES2 or MVS/SP-JES3 Version 1 Releases 3.3 and 3.5
•
VM/SP Release 3 or later without or with VM/SP High Performance Option
Release 3.4 or later.
VM/SP High Performance Option is required to support
more than 16Mb of processor storage.
The 4381 Processor Model Group 14 operating in System/370 extended
architecture mode
is supported by the following (which also support the 4381
Model Group 3):
• MVS/SP-JES2 or MVS/SP-JES3 Version 2 Release
1.1 or 1.3 with the
appropriate PTFs applied.
Section 01 : Highlights 3

• VM/XA Migration Aid Release 2 or later
•
VM/XA Systems Facility Release 1
The hardware facilities of, and
1/0 devices for, 4381 Processors can most
effectively be used by the MVS/370, MVS/XA, and
VM/370 operating systems.
To aid in the transition from
DOS/VSE to MVS/370 with installation of a 4381
Processor, two migration aids are provided (see discussion in Section 70:05). Less
effort
is required to convert from OS/VSl to MVS/370 than from DOS/VSE to
MVS/370 because of the basic compatibility between the OS/VSl and OS/VS2
operating systems.
Highlights of 4381 Processor Model Groups 11, 12, 13, and 14 are as follows:
• Upward compatibility with 4300 System/370 mode, System/370, and 30XX
architecture and programming systems has been maintained in 4381 Processors
through implementation of the System/370 mode of processor operation. This
mode provides compatibility for 4300 System/370 mode, System/370, and
30XX control programs and problem programs. Problem programs that
operate in 4341 Processors under a
DOS/VSE ECPS:VSE mode supervisor
can also operate in a 4381 Processor under a
DOS/VSE System/370 mode
supervisor if they are not processor- or time-dependent. The ECPS:VSE mode
implemented in 4341 Processors
is not implemented in 4381 Processors.
The System/370 extended architecture mode of operation, not provided in
4341 Processors,
is also implemented in 4381 Processors. This mode provides
compatibility for most 4300, 30XX, and System/370 problem programs and
most
MVS/370 subsystems but requires a control program with System/370
extended architecture support, such as MVS/XA.
• The following are instruction processing function features of 4381 Processors.
Instruction processing function logic
is implemented in large-scale integrated
technology. Logic chips (704-circuit) with faster circuit speeds than the
704-circuit chip used in most 4300 Processors are used in 4381 Processors.
However, the logic packaging and cooling technique implemented in 4381
Processors significantly increase the logic circuit density on a logic board
without the need for water cooling. (See Section 10:05 for a detailed logic
technology discussion.)
Implementation of a System/370 mode and a System/370 extended
architecture (System/370-XA) mode
is standard. The System/370
architecture implemented for System/370 mode operations includes nearly all
the extensions implemented in large-scale processors, such as the 308X and
3090.
System/370 extended architecture
is System/370 architecture with certain
changes and additions. The major new functions provided by this architecture
are 31-bit addressing and dynamic channel subsystem architecture. The 31-bit
addressing capability enables two gigabytes (over 2 billion bytes) of virtual
storage and real storage to be addressed, versus a maximum of over 16 million
bytes for the 24-bit addressing supported by System/370 architecture. A
bimodal operation
is supported that permits programs that use 24-bit
addressing and programs that use 31-bit addressing to operate concurrently
when System/370-XA mode
is in effect.
4 A Guide to the IBM 4381 Processor

The dynamic channel subsystem architecture eliminates channel addressing,
supports queuing of
all 1/0 requests, provides channel path selection for all
requested 1/0 operations in hardware, and supports an expanded 1/0
interruption mechanism and extended 1/0 device addressing.
The mode in which the 43
81 Processor is to operate is determined by the
operator at initial microcode load (IML) time. The mode selected remains in
effect until another IML
is performed and causes the System/370 mode or
System/370-XA mode microcode to be used for this IML.
The cycle time of 4381 Model Group
11 and 12 Processors is 68 nanoseconds.
For 4381 Model Groups
13 and 14, cycle time is 56 nanoseconds.
The instruction processing function design provides increased instruction
execution performance. Instruction prefetching
is implemented that results in
the overlap of instruction fetching with instruction execution during sequential
instruction processing. In addition, an eight-byte-wide arithmetic logic unit
is
used that enhances the performance of decimal and floating-point operations.
Improvements in the number of functions performed during the instruction
cycle of 4381 instruction execution (like those in 4341 Processors) result in the
faster execution of many other instructions, most of which are among the more
frequently used instructions.
The standard instruction set for 4381 System/370 mode of operation provides
decimal, binary, and floating-point arithmetic operations (including the
extended floating-point format that provides the equivalent of up to 34 decimal
digits).
For 4381 Model Groups 11, 12, and 13, it consists of the entire
instruction set defined for System/370 except for direct control and RESUME
1/0 instructions and those associated with multiprocessing (as discussed in
Section 10:10). For the 4381 Model Group 14, multiprocessing instructions
are also standard.
The standard instruction set for 4381 System/370-XA mode of operation
includes all the instructions defined for System/370 extended architecture. All
the semiprivileged and all the nonprivileged instructions in System/370
architecture are also defined for System/370 extended architecture but
differences exist in the set of privileged instructions supported by the two
architectures (see Section 10:
10).
Three engineering/scientific assists are provided for 4381 Processors. The
Multiply and Add Facility
is standard in 4381 Model Groups 11, 12, 13, and
14.
It is designed to improve the performance of certain mathematical
computations, such as matrix inversion, decomposition, and multiplication.
These computations are used, for example, in finite element analysis, linear
programming, and statistical analysis. This feature supports only long-format
(64-bit) floating-point numbers and can provide a reduction in instruction
processing function busy time of up to
35 percent for the instructions replaced
by the MULTIPLY AND ADD instruction (see Section 20:05).
The Square Root Facility
is standard in 4381 Model Groups 11, 12, 13, and 14
to improve the performance of square root operations involving long- or
short-precision floating-point arithmetic.
Section 01: Highlights 5

The Mathematical Function Facility (not implemented in 4341 Processors) is
standard in 4381 Model Group 12, 13, and 14 Processors and provides a group
of eight register-to-register floating-point instructions that perform elementary
mathematical functions. The supported functions are exponentiation and
natural and common logarithms. The instructions support short and long
precision for the two operands involved (see Section 20:05). This facility
reduces processor busy time by up to
65 percent for the assisted functions. It
permits selected scientific subroutines to be executed faster than with
conventional programming (FORTRAN subroutines).
Timing and debugging features like those in System/370, 30XX, and other
4300 Processors (3.3-ms-resolution interval timer, time-of-day clock, CPU
timer, clock comparator, monitoring feature, and program event recording) are
standard in 4381 Processors. The time-of-day clock and CPU timer have a
one-microsecond resolution.
The standard byte-oriented operands facility permits byte boundary alignment
for the operands of nonprivileged instructions, making it unnecessary to add
padding bytes within records or to blocked records to align fixed- or
floating-point data. In 4381 Processors, minimal performance degradation
results from the use of unaligned data.
Functions of the System/370 Extended Facility/Feature for 30XX Processors
are standard in 4381 Processors. These facilities are low address protection (to
protect the contents of locations 0 to 511 from accidental modification), the
TEST PROTECTION and INVALIDATE PAGE TABLE ENTRY
instructions (for control program use), the common segment facility (to
improve address translation performance for
MYS and VM/370
environments), MYS-dependent instructions (ECPS:MVS feature in 4381
Processors), and Virtual Machine Extended Facility Assist.
The facilities provided by the 3033 Extension feature for 30XX Processors are
standard in 4381 Processors. The Dual Address Space Facility for both modes
(which improves the performance of MYS/SP Cross Memory Services),
START
1/0 FAST RELEASE instruction queuing for System/370 mode only
(which
is basic to the System/370-XA mode channel subsystem), and two
MYS assists (included in the 4381 ECPS:MVS feature) are implemented in
4381 Processors. The suspend and resume facility provided by the 3033
Extension feature
is not implemented for 4381 System/370 mode of operation
but a comparable function
is basic to the channel subsystem defined for
System/370-XA mode.
Dynamic address translation and channel indirect data addressing features to
support a virtual storage
and/ or virtual machine environment are standard.
For System/370 mode (which uses 24-bit addressing), one virtual storage of
16,777,216 bytes (16Mb) maximum or multiple virtual storages up to
16M-bytes each can be supported. For System/370-XA mode (which uses
31-bit addressing), one virtual storage of up to 2,147,483,648 bytes (2
gigabytes) or multiple virtual storages of up to 2 gigabytes each can be
supported.
A segment protection facility (not provided for 4341 Processors) that provides
the ability to prevent stores to protected virtual storage segments
is standard
for System/370 mode. For System/370-XA mode, a page protection facility
is
6 A Guide to the IBM 4381 Processor

provided instead of the segment protection facility. Page protection can be
used to prevent any writing in protected 4K pages of virtual storage.
A
VM/370 hardware assist function (ECPS:VM/370) and an MVS hardware
assist facility (ECPS:MVS) are standard in 4381 Processors. ECPS:VM/370
and ECPS:MVS can be used concurrently to improve performance when
MVS/SP Version 1 executes in a virtual machine under the control of
VM/370 with the VM/System Product.
ECPS:VM/370 consists of the Virtual Machine Assist, Control Program
Assist, Expanded Virtual Machine Assist, Virtual Interval Timer Assist, and
Shadow-Table Bypass Assist components.
It can be used only when
System/370 mode is in effect.
ECPS:MVS consists of
13 privileged instructions and the page fault assist
function, all of which are operative during System/370 mode operations.
Six
of the 13 instructions are operative for System/370-XA mode operations. The
standard Virtual Machine Extended Facility Assist enables the ECPS:MVS
instructions to be executed directly by an MVS virtual machine to improve
performance.
Preferred Machine Assist (not provided for 4341 Processors)
is standard in
4381 Processors and can be used only during System/370 mode operations.
It
is designed to improve the performance of MVS/SP Version 1 running in a
preferred virtual machine.
Instruction retry
is standard to attempt to correct errors that occur during
instruction execution without programming assistance. For certain hardware
facilities (reloadable control storage, channel buffers, and the high-speed
buffer and its swap buffer), the instruction retry facility provides automatic
hardware reconfiguration to assign spare storage when a retry does not correct
an error. The reconfiguration facility permits continued system operation,
without performance degradation in some cases. Maintenance
is performed
when reconfiguration
is no longer possible.
The following are significant storage features of 4381 Processors.
All storage in a 4381 Processor-processor, control, high-speed buffer, and
local-is implemented using monolithic technology. The technology used for
processor storage in 4381 Processors provides much denser storage chips (64K
bits per chip
as in 4341 Processors and a 256K-bit chip for processor storage
above 16Mb) than
is used in System/370, 303X, or 308X processors (2K, 4K,
or 16K bits per chip).
A two-level storage system
is implemented, consisting of large processor
storage used
as backing storage for a smaller high-speed buffer storage. The
instruction processing function works mostly with the high-speed buffer so that
the effective processor storage cycle
is a fraction of the actual processor
storage cycle.
4K bytes for a 4381 Model Group 11, 32K bytes for a 4381 Model Group 12,
and 64K bytes for a Model Group
13 of high-speed buffer storage (where
K= 1024) are standard. The full buffer size is used when the page size in
effect
is 4K bytes. When page size is 2K bytes in a 4381 Model Group 11 or
12, only half of the high-speed buffer
is used. A doubleword of data is fetched
Section 01 : Highlights 7

from the buffer in 68 nanoseconds and stored in the buffer in 102 nanoseconds
for 4381 Model Groups
11 and 12. For a 4381 Model Group 13, 56 or 84
nanoseconds are required for a fetch or store, respectively.
For the 4381 Model Group 14, each of the two instruction processing
functions has its own dedicated 64K-byte high-speed buffer as a standard
feature. These two high-speed buffers operate using 4K-byte pages only.
Facilities for the required high-speed buff
er communication in a
multiprocessing environment are implemented in the Model Group 14,
including buffer-to-buff
er data transfer.
4Mb, 8Mb, and 16Mb of processor storage are available for the 4381 Model
Group
11 (where M=l,048,576). For 4381 Model Group 12 and 13
Processors, 8Mb, 16Mb, 24Mb, and 32Mb are available. A Model Group 14
can have 16Mb, 24Mb,
or 32Mb of processor storage. Store and fetch
protection and reference and change recording are standard. Store and fetch
protection are provided
on a 2Kb basis (one key for each 2Kb) for 4381
processors with up to 16Mb installed.
For 4381 processors with more than
16Mb installed, store and fetch protection are provided on a 4Kb basis.
A portion
of highest addressed installed processor storage in a 4381 Processor
will
not be accessible to programs, as in 4341 Processors. The amount of
unavailable processor storage for 4381 Processors (called auxiliary storage) is a
minimum
of 64Kb (104Kb for the Model Group 14) for System/370 mode of
operation for the minimum number of UCWs (128) defined. For
System/370-XA mode, a minimum of l 12Kb (220Kb for the Model Group
14) of auxiliary storage is required for zero subchannels and 128 control units
defined.
Reloadable control storage
to contain all the microcode required by the
instruction processing function
of 4381 Processors is standard. Use of
writable, instead of read-only, control storage offers the advantages of
improved system serviceability and ease of optional feature and engineering
change installation.
The TEST BLOCK instruction (not implemented in 4341 Processors) is
provided to enable the control program
to determine which 4Kb blocks of
processor storage
and/ or their associated one or two storage protect keys are
unusable because
of uncorrectable errors. Known unusable blocks and keys
are saved across power-offs. This instruction can also be used for processor
storage validation.
The TEST BLOCK instruction enables the operating system
to delete unusable
4Kb blocks from its list
of assignable page frames and prevents abnormal
program terminations that could result from the uncorrectable storage errors.
<
Error checking and correction (ECC) hardware is standard. It automatically
corrects all single-bit processor storage errors, and detects
but does not correct
all double-bit and most multiple-bit errors. Correction
of double-bit errors that
consist
of one solid and one intermittent error (which is not implemented in
4341 Processors)
is also provided via microcode (see discussion in Section
60:10).
8 A Guide to the IBM 4381 Processor

The following channel features are provided for 4381 Processors.
Two channel groups are available for Model Groups 11, 12, and 13. The
standard channel group consists of one byte multiplexer and five block
multiplexer channels addressed 0 through
5. The optional channel group
consists of six block multiplexer channels addressed 6 through
B. Block
multiplexer channel 5 in the standard channel group can be configured as a
byte multiplexer instead of
as a block multiplexer channel.
For the 4381 Model Group 14, one channel group consisting of one byte
multiplexer channel (0) and five block multiplexer channels
(1 through 5) is
standard for each of the two instruction processing functions. The fifth block
multiplexer channel in each channel group can be configured
as a byte
multiplexer channel. Optionally, one additional channel group, which provides
three additional block multiplexer channels for each channel group (a total of
six additional channels) can be installed.
Functionally, a byte multiplexer channel for a 4381 Processor
is equivalent to
that for System/370, 30XX, and other 4300 processors. The standard
(channel 0) and optional (channel 5) byte multiplexer channels in Model
Groups 11, 12, and
13 each have a 24Kb/sec maximum data rate (28Kb/sec
for the Model Group 14) for one-byte transfer operations for byte mode
operations. Unbuffered.burst
mod.e 1/0 devices cannot be attached to the
byte multiplexer channels in a 4381 Processor.
Functionally, a block multiplexer channel in a 4381 Processor
is equivalent to
that for System/370, 30XX, and 4300 processors. A block multiplexer
channel in 4381 Processors can also operate in selector channel mode.
The data streaming mode of channel operation that
is provided for 4341 and
30XX Processors
is standard for all the block multiplexer channels in a 4381
Processor. Data streaming mode enables certain 4381 channels to handle
faster data rates (up to 3Mb/sec) over a longer channel-to-control unit cable
length for attached control units that are also capable of operating in data
streaming mode (see discussion in Section 20:20). Both data streaming and
nonstreaming devices can be attached to the block multiplexer channels in a
4381 Processor.
For the standard channel group in a 4381 Model Group 11, 12, or 13, the
maximum aggregate data rate
is 14 Mb/sec. For the optional channel group in
a Model Group 11, the maximum aggregate data rate
is 8Mb/sec, providing a
22Mb/sec maximum aggregate for eleven block multiplexer channels. For a
Model Group 12, the optional channel group has a maximum aggregate data
rate of lOMb/sec, providing a 24Mb/sec maximum aggregate for the eleven
block multiplexer channels. The maximum aggregate data rate for the optional
channel group in a Model Group
13 is 16Mb/sec, with a 30Mb/sec maximum
aggregate data rate for eleven block multiplexer channels.
For the Model Group 14, a maximum aggregate data rate of 30Mb/sec for the
ten block multiplexer channels (15Mb/sec for each channel group)
is possible.
The maximum aggregate data rate for 16 block multiplexer channels
is
36Mb/sec (18Mb/sec for each eight-channel group).
Channels with data rates of up to 3
Mb/sec and the block multiplexing
capability support attachment to the 4381 Processor of 3380, 3375, 3370,
Section 01: Highlights 9

3330-series, 3340/3344, and 3350 direct access storage. These disk devices
have rotational position sensing capability and can be used only with block
multiplexer channels.
Optionally, one Channel-to-Channel Adapter can be installed in a 4381
Processor (any model group) and attached to any block multiplexer channel.
The adapter can be used to connect a channel in a 4381 Processor to a channel
in a System/360, System/370, 30XX, 4321, 4331, 4341, 4361, or another
4381 Processor. Alternatively, the 3088 Multisystem Channel Communication
Unit can be used to interconnect the 4381 Processor with certain other
processors via channels.
The fast release function of the START
1/0 FAST RELEASE (SIOF)
instruction (implemented only in Model Group 12 4341 Processors) and
queuing of SIOF instructions (not implemented in 4341 Processors) are
standard features in 4381 Processors. These functions are designed to reduce
I/ 0 processing time.
A 3205 Color Display Console, or a 3278 Model 2A Display Console or 3279
Model 2C Color Display Console equipped with an operator console keyboard
and operator control panel feature
is required as the operator console for a
4381 Processor. Display mode and (for System/370 mode only) a
printer-keyboard mode are standard. The display console natively attaches to
4381 Processors. The display console
is used for manual operations,
operator-to-operating system communication, and by the customer engineer to
perform diagnostic functions.
Up to three displays
and/ or printers can be natively attached to a 4381
Processor in addition to the required 3205, 3278 Model 2A, or 3279 Model 2C
console. The additional three units can be 3205 Color Display Consoles, 3278
Model 2A Display Consoles, 3279 Color Display Consoles Model 2C, 3268
Model 2 Printers, 3268 Model 2C Color Printers,
and/or 3287 Printers Models
1, 2, 1C, and/ or 2C in any combination with the restriction that 3205 displays
cannot be installed together with 3278 Model 2A or 3279 Model 2C displays.
The additional displays can be used
as alternate and/ or additional consoles.
The 3287 or 3268 Printer can be used for hard-copy backup of an operator
console that operates in display mode. Models
lC and 2C of the 3287 and the
3268 Model 2C provide color printing. A printer
is recommended for
hard-copy output when the display console operates in printer-keyboard mode.
The Remote Operator Console Facility (ROCF), a no-charge specify option
that requires the Remote Support Facility, gives an operator at a host location
the ability to dial up and control a powered-on remote 4381 Processor using a
3275 Display Terminal or an emulated 3275 attached to a host processor.
Host processor program support for ROCF
is provided by MVS/370,
MVS/XA, and
VM/370 with the appropriate program products installed (see
discussion in Section 40:15).
1/0 devices that attach to 4341 Processors and that are available from IBM
will also attach to 4381 Processors.
The Device Attachment Control Unit (DACU) can be attached to a block
multiplexer channel in 4381 Processors. The DACU provides two commonly
used industry interfaces for the attachment of non-IBM
1/0 devices: UNIBUS
10 A Guide to the IBM 4381 Processor

(a registered trademark of the Digital Equipment Corporation), which provides
a parallel direct memory access (DMA) interface, and EIA RS-232C, which
is
an industry standard serial communication interface. The DACU permits
attachment of a wide variety of non-IBM 1/0devices, such
as plotters,
sensors, graphic devices, laboratory instruments, and minicomputers. This
control unit makes a 4381 Processor suitable for a variety of engineering and
scientific applications.
• The large-scale integrated technology implemented in 4381 Processors for
most logic and all processor storage provides higher internal performance,
increased reliability, and compact processor unit design. The module-on-board
logic packaging eliminates one entire level of packaging (logic cards), and the
impingement cooling technique assures adequate cooling of the high-density
logic modules using only room-temperature air
as the cooling medium. (See
technology discussion in Section 10:05.)
• The power system hardware in 4381 Processors
is totally different from the
power hardware used in most 4341 Processors. The 4381 power hardware
increases reliability, reduces space requirements, and aids serviceability.
Improvements in the fault-locating ability and the usability of power
diagnostics have also been made.
• Extensive hardware and programming systems error recovery and repair
features for 4381 Processor hardware errors are provided to improve system
availability and serviceability. These features include enhanced facilities
implemented in other 4300 Processors, such
as automatic diagnosis of logout
data after a hardware error occurs to generate a reference code that identifies
the field-replaceable unit or the procedure to follow to attempt to locate the
malfunction. Additional recovery facilities (such as double-bit error correction
and hardware reconfiguration) are implemented.
The Problem Analysis facility
is provided for 4381 Processors. This facility is
designed to be used by the operator to aid in problem determination and can
result in faster fault isolation and reduced system downtime.
It provides
usability and functional improvements over the Problem Analysis facility
provided for 4341 Processors (see discussion in Section 60:15).
Inquiry into a remote data bank by the on-site customer engineer and remote
diagnosis of hardware failures by IBM support center personnel are supported
via the recommended, no-charge Remote Support Facility (RSF), which
is
functionally like RSF for 4341 Processors.
The physical components of a 4381 Processor configuration are a 4381
Processor, an operator console (a 3205 Color Display Console, 3278 Model
2A Display Console, or 3279 Model 2C Color Display Console), and 1/0
devices. The 4381 Processor, which is air-cooled, is shown in Figure 1 on
page 12.
The 4381 Processor unit contains two diskette drives (instead of one
as in a
4341 Processor). These drives (shown in Figure 1 on page 12 are easily
accessible to the operator and space
is provided to the left of the two drives to
store diskettes not in use. The second diskette drive
is required to support
System/370 extended architecture functions and operations and enables more
diagnostics (such
as Problem Analysis) to be online for ease of use. Two
Section 01 : Highlights 11