Systems
GC30-3004-4
FileNo. S360/S370-09
IBM 3704 and 3705
Communications Controllers
Principles of Operation
Preface
This r~ference publication contains the hardware oper- ationand programming requirements of the IBM 3704 and the IBM 3705 Communications Controllers. The information applies to the Il3M 3704, IBM 3705·1
and 3705-II except where specifically noted.
The publication is intended for any user of a, com .. , munications controller who is attempting etowrite or modify a 3704/3705 control program.'The'reader should have an understanding of basic teleprod!'ssing operations and a thorough knowledge of IBM'
System/3 60 and System/3 70' channel operations. e. The Introduction to the IBM 3704 and 3705 Commu..:
nications Controllers (GA27-3051) is a prerequisite publication. Related publications are the IBM 3105
Communications Controller Assembler Language ' manual (GC30-3003), the Synchronous Data Link
Control General Information manual (GA27-3093),·
the Guide to Using the IBM 3704 Communications Controller Control Panel (GA27-3086), andJhe Guide to Using the IBM 3705 Communications Controller Control Panel (G:A27-3087) ..
Other IBM p~cations concerning. the' COInnluriiC(l- tions control1l'"s are identifiedatld described in the
IBM System/360 and System/370Bibiiography;
GA22-6822.
This manual is divided into eleven chapters and three appendixes.
Chapter 1: Introduction
Provides a general description of the 3704/3705 and their functional units.
Fifth Edition (June 1976)
Chapter 2: System Structure
Describes the registers, interrupt scheme, and levels of the control program~
Chapter 3: Storage and Line Addressing
Describes the basic storage addressing procedure and the format for addressing the individual com- munication lines.
Chapter 4: Instruction Set
Describes each of the 3704/3705 emachine instruc- . , tions with-their format and condition codes. ' ,Chapters 5 through 10:
Describe the operation and programming require- ments of the Central Control Unit, the Types 1, 2, and 3 Communication Scanners, and the Types 1, '2, 3, and 4 Channel Adapters.
Chapter 11: Remote Communications Controller Describes the hardware and programming required to support a communications controller at a remote . location.
The appendixes contain (A) External register func- tions, (B) Inpu t/ Output instruction: bit definitions, and (C) Input/Output instruction summary.
This is a major revision of and makes obsolete GC30-3p04"3i: The Summary of Amendments section describes the changes made in:thisedition.
Changes are periodically made to the information hen;ljn; before using this publication in connection with the operation of IBM systems, consultthe l~test IBM System/370 Bibliography (GC20-o00l) and associated Technical Newsletters 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 System Communications Division, Publications Center, Department E01, P.O. Box 12195, Research Triangle Park, North Carolina . 27709. A form for reader's comments is provided at the back of this publication. If the form has been removed, comments may b'e sent to the above address. Comments become the property of IBM.
IBM 3704 and 3705 Communications Controllers Principles of Operation iii
Interface Control Word. 7-5 Business Machine Clocks 8-26
ICW Access 7-5 I/O Programming Considerations 8-27
ICW Modification 7-5 Program Levell (Error Routines) 8-27
Interface Control Word Format 7-6 Program Level 2 (Character Service) 8-27
Line Control Definer (LCD) States 7-9 Program Levels 3 and 4 (Lower Level Routines) 8-28
Primary Control Field (PCF) States 7-10 Autocall Interface Operation 8-28
Interface Mode Set-SDF Values 7-13 Interface Control Word for Autocall Operation 8-28
Business Machine Clocks 7-14 PCF States for Autocall Operation 8-28
I/O Programming Considerations . 7-15 SDF for Autocall Operation 8-29
Program Levell (Error Routines) . 7-15 PDF for Autocall Operation 8-30
Program Level 2 (Character Service) 7-15 Input/Output Instructions . 8-30
Program Levels 3 and 4 (Lower Level Routines) 7-16 Input Instructions 8-30
Autocall Interface Operation 7-16 Output Instructions. 8-32
Interface Control Word for Autocali Operation. 7-16 Diagnostic Functions 8-34
Primary Control Field for Autocall Operation 7-16 Diagnostic Wrap Test . ·8-34
Serial Data Field for Aut6call Operation. 7-17 Modem Wrap Test 8-35
Parallel Data Field for Autocall Operation 7·18 ICW Diagnostic Mode Test 8-36
Input/Output Instructions . 7-18
Input Instruction~ 7-18 Chapter 9: Type 1 and Type 4 Channel Adapters 9-1
Output Instructions. 7-19 Operation and Data Flow 9-1
SDLC. 7-20 Type 1 and Type 4 CA Modes of Operation 9-1
Line Control Definer (LCD) States for SDLC 7-21 Channel Adapter States 9-1
Primary Control Field (PCF) States for SDLC 7-22 Initial Selection State 9-1
Diagnostic Functions 7-23 Data Transfer State· . 9-2
Diagnostic Wrap Test 7-23 Status Transfer State 9-2
Modem Wrap Test 7-24 Channel Adapter Registers. 9-2
Chapter 8: Type 'ommunication Scanner
Initial Selection Control Register (ISCR) . 9-2
8-1 Data/Status Control Register (DSCR) 9-2
Operation and Data Flow 8-1 Initial Selection Address and Command Register
Type 3 Scanner Registers 8-1 (IASCR) 9-2
Local Storage 8-1 Initial Selection Status Register 9-2
ICW Work Register . 8-1 NSC Status Register 9-2
ICW Input Register . 8-1 Error/Control/Condition Register. 9-2
Attachment Buffer Address Register (ABAR) 8~1 Local Store Registers 9-3
Display Register . 8-2 Extended-Buffer Mode Local Store (Type 4
Scanner Output Register 8-2 '" CA Only) 9-3
Scanner Check Register 8-2 Extended-Buffer Mode Control Register (Type 4
Diagnostic Buffer Address Register (DBAR) . 8-2 CA Only) 9-3
Cycle Steal Buffer Address Register (CBAR) 8-2 Extended-Buffer Mode Counter Register. 9-3
PDF Array Format 8-2 I/O Device Addresses 9-3
Ending the Cycle Steal Operation. 8-4 Initial Selection Address 9-4
PDF-rull and PDF Empty Conditions 8-4 Transfer Sequence Addresses 9-4
Scanner Initialization 8-4 Channel Adapter Interrupt Requests 9-4
POI' Array Reset 8-5 Levell Interrupt Request 9-4
Type 3 Scallner Addressing 8-5 Level 3 Interrupt Request . 9-5
Scan Addressini.! . 8-5 Channel Commands. 9-6
Scan Counter 8-5 Channel Adapter Status Presentation . 9-7
Upper Scan Lilllit 8-5 Initial Selection Status . 9-7
Address Suhstitution 8-5 Final S ta tus 9-7
High Speed Select Option 8-6 Emulation Mode Test I/O 9-7
Program Addressing. 8-7 Native Mode Asynchronous Status 9-8
Interface Control Word (lCW) 8-7 Stacked Initial Status 9-8
lew Access 8-7 Stacked Final Status 9-9
lew Modification 8-10 Status Transfer Sequences 9-10
Interface Control Word Format 8-10 ESC Final Status 9-10
Line Control Definer (LCD) States 8-16 NSC Final Status 9-10
Primary Controll;ield (PCF) States 8-17 NSC Channel End Status 9-10
PCF/EPCF States-BSC 8-17 Data Transfer Sequences-Non-EB Mode. 9-10
PCF/EPCF States-SDLC 8-20 Outbound Data Transfer 9-10
ICW Status Byte. 8-23 Inbound Data Transfer 9-11
lew Status Indicators for BSC 8-23 Data Transfer Sequences-EB Mode (Type 4 CA) 9-11
ICW Status Indicators for SDLC 8-25 Outbound Data Transfer 9-11
Interface Mode Set-SDF Values 8-25 Inbound Data Transfer. 9-11
Input/Output Instructions . Input Instructions . Output Instructions.
Error Indications Channel Bus In Check
Channel Bus Out Check in EB Mode In/Out Instruction Accept Check.
I/O Check on Input or Output X'6D' Instruction in EB Mode
. CCU Bus Out Check
CCU Bus Out Check on Output X'6D' Instruction in EB Mode.
Local Store Parity Check .
Chapter 10: Type 2 and Type 3 Channel Adapters Operation and Data Flow
Cycle Steal Operation . Channel Adapter States
Channel Adapter Registers. . . . Inbound Data Control Word' Address
Register (INCW AR) .
Outbound Data Control Word Address Register (OUTCW AR)
Control Word Byte Count Register (CWCNTR) Channel Adapter Sense Register (CASNSR) . Channel Adapter Status Register (CASTR) . Channel Adapter Control Register (CACR) . Channel Adapter Check Register (CACHKR) Channel Adapter Mode Register (CAMR) . Channe1 Bus Out Diagnostic Register (CBODR) . Cycle Steal Address Register (CSAR) .
Channel Adapter Data Buffer (CADB) Channel Tag Diagnostic Register (CTDR) Channel Adapter Command Register (CMDR) Channel Adapter Control Word
Control Word Command Codes Control Word Conventions.
Channel Adapter Interrupt Requests Channel Commands.
Write (X'O 1 ') Write Break (X'09') . Write IPL (X'05') Read (X'02') . Sense (X'04') No-Op (X'03') Test I/O (X'OO') . Nonstandard Commands Status Servicing .
Initial Status . Ending Status Stacked Status Asynchronous Status
9-12 9-12 9-13 9-15 9-15 9-15 9-15 9-15 9-15 9-16 9-16 10-1 10-1 10-2 10-2 10-2 10-3 10-3 10-3 10-3 10-3 10-4 10-4 10-4 10-4 10-4 10-4 10-4 10-4 10-5 10-5 10-7 10-7 10-7 10-7 10-7 10-8 10-8 10-8 10-8 10-8 10-8 10-9 10-9 . 10-9 10-9 .10-10
Multiple-Channel Operation
Type 3 Channel Adapter-Channel Interface States Type 3 CA Response to Resets
Input/Output Instructions . Input Instructions . Output Instructions.
Error Indications
Chapter 11: Remote Communications Controller Local/Remote Communication Link .
Remote Program Loader
Remote Program Loader Input Instructions Remote Program Loader Output Instructions Remote Program Loader CCU Instructions Disk Storage Controller
Track Access.
Track Format
Disk Read and Write Operations Initial Program Load
Remote Power Off .
Appendix A-External Register Addresses
Appendix B-Input/Output Instruction Bit Definitions Type 1 Scanner Input Instructions
Type 1 Scanner Output Instructions
~Type 2 Scanner Input -Instructions Type 2 Scanner Output Instructions Type 3 Scanner Input Instructions Type 3 Scanner Ol,ltput Instructions Type 1 and Type 4 CA Input Instructions Type 1 and Type 4 CA Output Instructions . Type 2 and Type 3 CA Input Instructions Type 2 and Type 3 CA Output Instructions . Remote Program LoaderInput Instruction.
Remote Program Loader Output Instructions CCU Input Instructions
CCU Output Instructions .
.\
Appendix C - Input/Output Instruction Summary Charts Glossary .
Index.
.10-10 .10-10 .10-11 .10-11 .10-12 .10-12 .10-12 11-1 11-1 11-1 11-3 11-3 11-3 11-3 11-3 11-4 11-4 11-5 11-7 A-I B-1 B-1 B-3 B-6 B-8 B-l1 . B-14 B-18 B-21 B-25 B-30 B-35 B-35 B-37 B-41 C-l Glos-l . X-I
IBM 3704 and 3705 Communications Controllers Principles of Operation v
Figures
1-1 Line Attachment Capacity and Storage Size by Model. t:·2 6-3 Interfaces Serviced According to Priority 6-4 1-2 Maximum Hardware Configuration of the 3704 6-4 Business Machine Clocks and Warm Up Period 6-6
Communications Controller 1-4 6-5 Type 1 Scanner Business Machine
1-3 Channel Adapter/Communication Scanner Oock Selection 6-7
Combinations 1-5 7-1 Type 2 Communication Scanner Operation 7-2
1-4 System Data Flow 1-10 7-2 Upper Scan Limit ' 7-4
2-1 General Register Groups 2-1 7-3 Address Substitution Control . 7-4
2-2 Program Levels. . 2-3 7-4 Interface Control Word-Type 2 Scanner 7-7
2-3 Interrupt Priority Example 2-5 7-5 Type 2 Communication Scanner Business Machine
3-1 Storage Address Bit Positions Clock Selection 7-14
(Without Extended Addressing) • 3-1 7-6 Setting ABAR and ICW Input Register 7-15
3-2 Storage Address Bit Positions 8-1 PDF Array Format .. 8-3
(With Extended Addressing) . 3-1 8-2 Upper Scan Limit 8-6
3-3 Type 1 Scanner Interface Address Bits 3-3 8-3 Address Substitution Control 8-6 3-4 Types 2 and 3 Scanner Interface Address Bits 3-3 8-4 High Speed Select Control . 8-7
3-5 Storage Address Assignments 3-4 8-5 Interface Control Word-Type 3 Scanner 8-8
4-1 Instruction BitStructure 4-2 8-6 Type 3 Communication Scanner Business Machine
4-2 Instruction Format . 4-3 Clock Selection 8-26
5-1 Operations that Set the Lagging Address Register 5-2 8-7 Setting ABAR and ICW Input Register 8-27 5-2 Protect Key Address Bits 5-4 10-1 Type 2 and Type 3 Channel Adapter Control Word 10-6 5-3 Storage Key Addresses . ,; 5-4 11-1 Teleprocessing System with Local and Remote
6-1 Type 1 Communication Scanner Operation 6-1 Communications Controllers. 11-2
6-2 Level 2 Program Flow (Type 1 Commul\ication 11-2 IPL-Remote COQllllunications Controller 11':6
sea?), 6-2'
Abbreviations
ABAR attachment buffer address register HIO halt I/O
ACR add character register instruction IAR instruction address register
ACR abandon call and retry IC insert character instruction
ACU automatic calling unit ICT insert character and count instruction
AHR add halfword register instruction ICW . interface control word
ALU arithmetic logic unit IN input instruction
AR add register instruction INCWAR in-bound control word address register
ARI add register immediate instruction I/O input/output
ATT attention IPL initial program load
B branch instruction 'IPR interrupt priority register
BAL branch and link instruction L load instruction
BALR branch and link register instruction LA load address instruction
BB branch on bit instruction LAR lagging address register
BCL branch on C latch instruction LCD line control identifier
BCT branch on count instruction LCOR load character with offset
BSC binary synchronous communication register instruction
BZL branch on Z latch instruction LCR load character register instruction
CA channel adapter LH load halfword instruction
CACHKR channel adapter check register LHOR load halfword with offset
CACR channel adapter control register register instruction
CADB channel adapter data buffer or LHR load halfword register instruction
channel adapter diagnostic busy LIB 'line interface base
CAMR channel adapter mode register LOR load with offset register instru~n
CASNSR channel adapter sense register LR load register instruction
CASTR channel adapter status register LRI load register immediate instruction CBODR channel bus out diagnostic register NCR AND character register instruction CCR compare character register instruction NHR AND halfword register instruction
CCU central control unit NR AND register instruction
CE channel end NRI AND register immediate instruction
CHR compare halfword register instruction NSC native subchannel
CMDR channel adapter command register OCR OR character register instruction
COS call originate status OHR OR halfword register instruction
CPU central processing unit OR OR register instruction
CR compare register instruction ORI OR register immediate instruction
CRC cyclic redundancy check OUT output instruction
CRI compare register immediate instruction OUTCWAR out-bound control word address register
CRQ call request PCF primary control field
CSAR cycle steal address register PCI program controlled interrupt
CTDR channel tag diagnostic register PDF parallel data field
~ CTRL control PND present next digit
ICW control word RA register and immediate address operation
CWAR control word address register RE register and external register operation
CWCNTR control word byte count register RI register and immediate operand operation
DBAR diagnostic buffer address register ROS read-onl y-storage
DE device end RR register to register operation
DLO data line occupied RS register and storage operation
DPR digit present RSA register and storage with count operation
DTR data terminal ready RT branch operation
EB extended-buffer (mode) RTS request to send
ESC emulator sub channel SAR storage address register
EXIT exit instruction SCF secondary control field
FDX full duplex SCR subtract character register instruction
HDX half duplex SDF serial data field
HEX hexadecimal SDLC synchronous data link control
IBM 3704 and 3705 Communications Controllers Principles of Operation vii
SDR storage data register TAR temporary address register SHR subtract halfword register instruction TIC transfer in channel
SIO start I/O TIO test I/O
SM status modifier TRM test register under mask instruction
SR subtract register instruction UC unit check
SRI subtract register immediate instruction UE unit exception
ST store instruction XCR exclusive OR character register instruction
STC store character instruction XHR exclusive OR halfword register instruction
STCT·· store character and count instruction XR exclusive OR register instruction
STH store halfword instruction XRI exclusive OR register immediate instruction
SVC supervisor call
Summary of Amendments-Fifth Edition
The fifth edition contains the following changes:
• The publication now applies to the 3705-I1 as well as the IBM 3704 and 3705-1. Distinctions between the three machines appear as appropriate.
• A new chapter-Chapter 8-describes the Type 3 Commu;.
nication Scanner. Former Chapters 8, 9, and 10 are re- numbered to Chapters 9, 10, and 11, respectively.
• Chapter 9 (formerly Chapter 8) now applies to the Type 4 Channel Adapter as well as the Type 1 Channel Adapter.
Distinctions between the two types "appear as appropriate.
• Appendixes Band C are updated to reflect the new Input and Output instructions and bit definitions for the Type 3 Communication Scanner and the Type 4 Channel Adapter.
In addition to the foregoing, several minor corrections and clarifications appear in this publication. Technical changes are denoted by a vertical line at the left of the revised text or illustration.
Summary of Amendments-Fourth Edition The fourth edition contained the following changes.
Hardware Changes
The following changes to the manual are the result of new 3704 and 3705 hardware features and capabilities.
!
Remote Communications Controller I
Information is now included on communications controllers that are at a location remote from the host processor. Chapter 10 deals exclu- sively with the remote communications controllers, and Appendixes A, B, and C describe the Input/Output instructions allocated to the remote program loader.
SDLC
Information on a new line control discipline, Synchronous Data Link Control (SDLC), is includyd in Chapter 7, and Input/Output instruc- tions for SDLC are described in the appendixes.
3704 Type 2 Scanner Additional Capability
The 3704 with a Type 2 Communication Scanner can now support two line interface bases and up to 26 communication lines if the addi- tional capabjIity is selected. The additional capability is described in Chapter 7 and.at other applicable places where the Type 2 Scanner is described.
Manual Changes
The following additional changes have been made to the manual, but they do not reflect changes to the product.
Panel Information Removed
All information on the 3704 and 3705 control panels has been re- moved from this manual. Refer to the Guide to Using the IBM 3704 Communications Controller Control Panel and the Guide to Using the IBM 3705 Communications Controller Control Panel for information that was formerly in Chapter 10.
LIB and Line Set Information Removed
Appendix D, which described the line interface bases and Hne sets, has beefl removed. Refer to the Introduction to the IBM 3704 and 3705 Communications Controllers for this information.
TNL Incorporated
Technical Newsletter GN30-3024, which added information on the Type 3 Channel Adapter, has been incorporated into this edition.
Miscellaneous Changes
Numerous minor editorial and technical changes have been made in this revision. The index and table of contents have been updated to reflect all changes.
IBM 3704 and 3705 Communications Controllers Principles of Operation ix
The IBM 3704 and 3705 Communications Controllers are transmission control unIts with processing capabili- . ties that offer advantages not available in other IBM transmission control units. A control program residing in the cont~oller storage performs many of the func- tions previously performed by the central processing unit. The assumption of these functions by the con- troller increases the availability of the CPU to process other programs and to perform more involved . message-processing functions for the teleprocessing system.
The controller is priority-interrupt driven. This al- lows the control program to handle service requests at five different priority levels.
The communications controller performs, under program control, the normal transmission control unit functions such as line-control, control character recog- nition, line time-out, character assembly and disassem- bly, and redundancy checking. The control program can also (1) handle all polling and addressing of com- munications lines to. determine if a line is ready to send or receive data, (2) take over data link control, (3) add framing characters to the beginning and end of blocks of data, and (4) translate from line code into code recognizable to a message-processing program, 'and vice versa. Most error recovery procedures can be handled by the communications controller, thus reliev- ing the CPU of a time-consuming and storage- ' consuming teleprocessing function. The control pro- gram can also provide dynamic buffering for incoming d~ta and basic message-processing functions.
Host System Interface .
The communications controllers may be attached, VIa the proper channel adapter, to a System/360, Model 30, 40, 50, 65,67 (in 65 mode), 75; or 195, or System/370 Models 125 through 195. A 3705 with a Type 2 or Type 3 Channel Adapter requires only one sub channel address, and the inter- face may be connected to a byte multiplexer, block multi- plexer, or selector channel. The Type 3 Channel Adapter enables the 3705 to be attached to tightly-coupled multipro- cessor systems as a shared symmetrical I/O unit, and to a uniprocessor as an I/O unit with an alternate path capability.
The Type 1 Channel Adapter in a 3704 or 3705 operates only on a byte multiplexer channel; a Type 4 Channel Adapter in a 3705 operates on a byte multiplexer, block multiplexer, or selector channel. The channel may require more than one sub channel address, depending on the mode of operation (2701, 2702, or 2703 emulation requires a range of sub channel addresses);
Chapter 1: Introduction
Note: A remote communications controller does not interface with the host system and therefore does not have a channel adapter.
System Support Programs
IBM provides control programs that schedule and con- trol all 3704 or 3705 Communications Controller sys- tem resources. Also provided are system support pro- grams. These are host processor programs used prima- rily to generate or assemble a user's control program and to provide IPL and dump facilities for the control- ler. The support programs operate under control of the host supervisor.
3704 Description
The 3704 is a low-entry control unit that is upward and downward compatible with a 3705 without Extended / Addressing .. It is available in four models that are defined by
the amount of storage installed. Figure 1-1 lists the models of the 3704 and the storage capacity of each model.
The 3704 consists of a single module that can contain a Central Control Unit, a control panel, 16K bytes of storage, a channel adapter, and
a:
communication scanner. Either a Type lora Type 2 Scanner can be installed, but the chan- nel adapter is limited to a Type 1 Channel Adapter. The maximum number of communication lines is 32 when the Type 1 Scanner is installed and 10 (26 with additional cap- 'ability) when the Type 2 Scanner is installed. Figure 1-2shows the maximum configuration of the 3704 hardware.
3705 Description
The 3705-1 and 3705-11 are available in 20 and 32 models, resp~ciively. The different models provide varying combin- ations of storage size and maximum line attachment capac- ity. Figure 1-1 lists all models' of the 3705-1 and 3705-11 with their respective line attachment capacities and storage sizes. The values shown in the middle column represent only the maximum number of lines physically attachable to the controller. The actual number of lines the controller can support depends on such factors as the line speeds (data . rates) usedand the throughputcapacity of the control
program..' .
Each model is represented by a l~tter and a numeral such as E3. The letter indicates the maximum number of rullf-duplex lines that can be physi.cally attached to the con- . troller, and the numeral indicates the amount of storage installed in the controller. All 'E' models, for example, can accommodate up to 64 half-duplex lines; all '3' models of the 3705-1 have 80K bytes of storage and all '3' models of the 3705-11 have 96K bytes of storage.
IBM 3704 and 3705 Communications Controllers Principles of Operation 1-1
The 'A' and 'E' models of the 3705 comprise a stand- alone base module contain'ing a central control unit (CCU), a control panel, at least 16K bytes (3705-1) or 32K bytes (3705-II) of storage, and provisions for a channel adapter, a two-channel switch (except for a Type 3 Channel Adapter), a communication scanner, and line interface bases (LIB) and line sets to accommodate up to 64 half-duplex lines. Each LIB can have up to eight line sets (depending on line set type), each capable of accommodating 1 or two half- duple .. lines.
Each higher letter designation (B, C, D, F, G, H) indicates that the controller contains one or more expansion modules that provide additional line attachment capacity (for a 3705-II) or additional storage and line attachment capacity (for a 3705-1). (All storage in a 3705-11 is contained in the base module, regardless of amount; storage increments in a 3705-1 may extend into the first, second, or third expansion module, depending on amount.) All 'B' and 'F' models com- prise a base module and a single expansion module; all 'C' and 'G' models comprise a base and two expansion modules;
and all 'D' and 'H' models have a base and three expansion modules.
The base module of a 3705-1 contains 16K or 48K bytes of storage and a Type 1 or Type 2 Communication Scanner capable of supporting up to four line interface bases (LIB).
Each expansion module of a 3705-1 can contain 0, 32K, or 64K bytes of additional storage and (1) a Type 2 Com- munication Scanner capable of supporting up to six LIBs, or (2) a Type 3 Communication Scanner and up to four LIBs. The first expansion module can also contain a Type 2, 3, or 4 Channel Adapter and a two-channel switch.
The base module of a 3705-II contains from 32K to 256K bytes of storage and (1) a Type 2 Communication Scanner and up to four LIBs, or (2) a Type 3 Communication Scan- ner and up to three LIBs.
Each expansion module of a 3705-II can contain either a Type 2 Communication Scanner and up to six LIBs or'a Type 3 Communication Scanner and up to four LIBs. The first expansion module can also contain a Type 2, 3, or 4 Channel Adapter and a two-channel switch.
Model IBM 3704 A1 A2 A3 A4 IBM 3705-1 A1 A2 B1 B2 B3 B4' C1 C2 C3 C4 C5 C6 01 02 03 04 05 06 07 08 IBM 3705-/1 E1
E2 E3 E4 E5 E6 E7 E8 - F1 F2 F3 F4 F5 F6 F7 F8 G1 G2 G3 G4 G5 G6 G7 G8 H1 H2 H3 H4 H5 H6 H7 H8 Figure 1-1.
Maximum Number of Storage Lines Attachable Size (K)
32 16
32 32
32 48
32 64
64 16
64 48
160 16
160 48
160 80
160 112
256 16
256 48
256 80
256 112
256 144
256 176
352 16
352 48
352 80
352 112
352 144
352 176
352 208
352 240
64 32
64 64
64 96
64 128
64 160
64 192
64 224
64 256
160 32
160 64
160 96
160 128
160 160
160 192
160 224
160 256
256 32
256 64
256 96
256 128
256 160
256 192
256 224
256 256
352 32
352 64
352 96
352 , 128
352 160
352 192
352 224
352 256
Line Attachment Capacity and Storage Size by Model
Storage
The communications controllers, like most central process- ing units, contain their own internal storage array. This stor- age provides a residence for the control program and a tem- porary storage area for data as it is being assembled or dis- assembled in preparation for transfer to the host processor or a terminal. The numeric part of the model designation (for example, '7' in E7) indicates the amount of storage installed in the controller (see Figure 1-1).
3705-1 storage ranges from 16K to 240K bytes, in incre- ments of 32K bytes. The read/write storage cycle time is 1.2 microseconds.
3705-11 stor~ge ranges from 32K to 25.6K bytes, in incre- ments of 32K bytes. The read/write storage cycle time is 1.0 microsecond.
3704 storage ranges from 16K to 64K bytes in increments
·1
of 16K bytes. The read/write storage cycle time is 600 nanoseconds.
Bytes of storage are handled separately or grouped together in fields. A halfword is a group of two consecutive bytes and is the basic building block of instructions. A word is a group of four consecutive bytes. The location of any field or group of bytes is specified by the address of its left- most byte.
Central Control Unit
The Central Control Unit (CCU) contains the circuits and data flow paths to execute the instruction set, and to control storage, the comm unication sca"nners, and the channel adapters. The CCU operates under con- trol of the programs residing in storage.
Adapters
Two different adapters are reg uired within the communica- tions controller to connect the Central Control Unit with the host channel and the communication lines. These are the communication scanner (connection between CCU and communication line), and the channel adapter (connection between CCU and host channel). The communication scan- ners for the communications controllers come in three ver- sions, and the channel adapters come in four versions. The . Type 1 Scanner and Types 1 and 4 CA have low functional hardware capabilities and require more program control than the Type 2 and Type 3 Scanner and the Type 2 and Type 3 CAs. The Type 2 and Type 3 Scanner and Type 2.and . Type 3 CAs have more functional hardware capabilities and
therefore require less program control while providing increased performance.
Figure 1-3 shows all poss~ble combinations of communi- cation scanners and channel adapters, including the maxi- mum number that can be installed for each model of the 3705 controller. The 3704 supports either a Type 1 or a Type 2 Scanner, but only supports the Type 1 Channel Adapter.
Channel Adapters
Four types of channel adapters (CAs) are available. The Type 1 and Type 4 CA provide for local attachment to a System/360 or System/370 byte multiplexer channel.
These adapters contain the hardware circuits necessary to assist the program in emulating an IBM 2701,2702, or 2703 as well as to allow operation of the controller in native mode. To operate in emulation mode, the controller requires multiple sub channel addresses: one for each line address and one for native mode IPL.
The Type.1 CA transmits data to and from the byte-mul- tiplexer channelin bursts of up to four bytes. The Type 4 CA transmits data in bursts of up to 32 bytes, if operating in extended buffer mode.· When not in this mode, the Type 4 CA transmits to and from the channel in bursts of up to four bytes.
The Type 2 and Type 3 CAs: which are available for the 3705 only, provide for local attachment to a System/370 byte multiplexer, block multiplexer, or se-lector channel.
With the Type 2 or Type 3 CA, the 3705 appears as a single control unit on the host processor channel and uses a single sub channel address. The Type 2 and Type 3 CAs operate in the native (one host sub channel address) mode only.
All data transfer between 3705 storage and the Type 2 and Type 3 Channel Adapters is by cycle steal operation.
That is, when the CA has data to put in storage, it preempts (under hardware control) the necessary machine cycles to transfer the data. Data transfers from storage to the chan- nel adapter also use the cycle steal technique. A cycle steal operation is accomplished by hardware circuits and does not affect the logical operation of the program.
A second channel adapter (Type 2, 3, or 4) can be installed in the first expansion module of a 3705 Model B, C, D, F, G, or H. When two channel adapters are installed, they operate independently. The adapter in the base module is called the first adapter (CA-1) and the adapter (n the expan- sion module is called the second adapter (CA-2). Figure 1-3 shows the possible combinations.
IBM 3704 and 3705 Communications Controllers Principles of Operation 1-3
Model A1 16K Storage
16K Storage
Model A3 16K Storage
Model A4 16K Storage
L _______ --J
Expansion Feature
3704 ComMunications Controller
Control Panel
Central Control Unit
Expansion
FUJ
---,
I
I
Type 1 Type 2 f Scanner Scanner I I I I
_ _ I
LIB
+ +
Line Line
Sets Sets
LIB
+ +
Line Line
Sets Sets
Figure 1-2. Maximum Hardware Configuration of the 3704 Communications Controller
Channel Adapter
Two- Channel Switch
Remote Program Loader
'-- -.,,, .. . ~. . ,~, .). ~ ...
Channel Communication 3705-1 3705-11
Adapter Type Scanner Type Model ,
Model
,,'
1 2 3 4 1 2 3 A B C D E F G H
1 1 * x x x (note 4)
1 1 * x x x *
2 * x x *
3 * ,
x *
4 * ,,' *
1 1 * x x x *
2 * x x *
,3
*
"X *4' ' , "
" * ",;, *
1 ",' * '*
2 x x
2 *~~ ,x x *
3 * x *
4 * *
1 1 *
2 *
3 (note 2) *
4 '~
2 1 *
2 (note 2) *
3
*
4 *
1 1 1 * x x *
1 2 * X It,'
1 3 * *
2 1 * x *
2 2 * :*
3 1 * *
2 1 1 * x x *
1 2 * x *
1 3 ", * *
2 1 * x *
2 2 * *':
3 1 * *
1 1 * x x x *
2 * x x *
3 * x *
4 * *
2 1 * x x *
2 * x x *
3 * x *
4 * *
1 1 *
2 (note 2) *
3 *
4 *
2 1 (note 2) *
2 *
3 *
4 *
1 1 1 * x x
..
1 2 * x *
1 3 * *
2 1 * x *
2 2 * *
3 1 * *
Figure 1-3. Channel Adapter/Communication Scanner Combinations (Part 1 of 3)
IBM 3704 and 3705 Communications Controllers Principles of Operation 1-5
Channel
Adapter Communication 3705-/ 3705-/1
Type Scanner Type Model Model
1 2 3 4 1 2 3 A B C D E F G H
2 1 1 * x x ...
1 2 * x *
1 3 * *
2 1 * x *
2 2 * *
3 1 * *
1 1 * x x x *
2 * x x *
3 * x *
4 * *
2 1 * x x *
2 * x x *
3 * x *
4 * *
1 1 *
2 *
3 (note 2) *
4 ' *
,
2 1 (note 2) *
2 * (note 3)
3 *
4 *
1 1 1 * x x *
1 2 * x *
1 3 * *
2 1 * x *
2 2 * *
3 1 * ~ 'J *
2 1 1 * x x *
1 2 * x *
1 3 * * (note 3)
2 1 * x *
2 2 * *
3 1 * *
1 1 1 * x x (note 4) (note 1)
1 1 1 * x x *
2 * x x *
3 * x * (note 1)
4 * *
1 1 1 * x x (note 4) (note 1)
1 1 1 * x x. *
2 * x x '*
3 * x *
4 * *
1 1 1 * x x *
2 * x x *
3 * x *
4 * *
1 1 1 *
2 (note 2) *
3 *
4 *
Figure 1-3. Channel Adapter/CommuD:ication Scanner Combinations (P~rt 2 of 3)
Channel
Adapter Communication 3705-1 3705-/1
Type Scanner Type Model Model
1 2 .3 4 1 2 3 A B C D E F G H
1 1 1 1 * x x *
1 2 * x *
1 3 * *
2 1 * x *
2 2 * *
3 1 * *
1 1 1 * x x *
2 * x x *
3 * x * (note 5)
4 * *
1 1 1 *
2 (note 2) * (notes 1 and 5)
3 * I
4
*
1 1 1 1 * x x *
1 2 * x * (notes 1 and 5)
1 3 * *
2 1 * x *
2 2 * *
3 1 * *
1 1 1 * x x *
2 * x x * (notes 1 and 5)
3 * x *
4 * *
1 1 1 *
2 (note 2) * (notes 1 and 5)
3 *
4 *
1 1 1 1 * x x *
1 2 * x *
1 3 * *
, (notes 1 and 5)
2 1 * x *
2 2 * *
3 1 * *
*indicates, for a 3705-11, the model of 3705 required to accommodate the number of channel adapters and communication scanners shown at left.
*indicates, for a 3705-1, the smallest model of 3705 required to accommodate the number of channel adapters and communication scanners shown at left.
x indicates other models of 3705-1 that can accommodate t~e number of channel adapters and com- munication scanners shown at left; the larger model so indicated may be required if the storage size required exceeds the capacity of the model indicated by *.
Note 1: Communication ~ver both CAs can occur only when the control program is performing emu- lation subchannel operations over the Type 1 or 4 CA and na:tive subchannel operations over the other CA.
Note 2: A 3705-1 cannot contain only Type 3 Scanners; it can contain Type 3 Scanners in each expansion module if the base module contains a Type 2 Scanner.
Note 3: Communication over both Type 4 CAs cim occur only when the control program performs emulation subchannel operations over both CAs or native subchannel operations over one CA and emulation subchannel operations over the other.
Note 4: A 3705-11 cannot contain Type 1 Scanners.
Note 5: The Type 4 CA must be installed in the base module when the controller contains a Type 4 and a Type 2 CA or a Type 4 and a Type 3 CA.
Figure 1-3. Channel Adapter/Communication Scanner Combinations (Part 3 of 3)
IBM 3704 and 3705 Communications Controllers Principles of Operation 1-7
