SY27 2512 3_3274__1_21_31_Maintenance_Concepts_Mar81 3 3274 1 21 31 Maintenance Concepts Mar81

SY27-2512-3_3274__1_21_31_Maintenance_Concepts_Mar81 SY27-2512-3_3274__1_21_31_Maintenance_Concepts_Mar81

User Manual: SY27-2512-3_3274__1_21_31_Maintenance_Concepts_Mar81

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Maintenance Library

Control Unit
Models 1A, 18, 1C, 10, 21A, 218, 21C, 210, 31A, 31C and31D
Maintenance .Concepts
.

SY27 -2512-3

SY27-2512-3

Preface

This manual contains the information needed by the support Field Engineering (FE) Customer Engineer to maintain
the 3274 Control Unit Models 1A, 18, 1C, 10, 21A,21B,
21C, 210, 31A, 31C and 31 D.
Note: For purposes of brevity and clarity, the one- and
two-digit numbers associated with the 3274 Models A, 8,
C, and D. units are not used in this manual. All unit designations are abbreviated by model type only~ such as: 3274
Model A, 3274 Model 8,3274 Model C and 3274 Model D.
The maintenance procedures described in this manual and
performed by the Support Customer Engineer represent a
part of the overall support structure for the 3274 Control
Unit. This support structure begins at the 3274 operator
level and is briefly described as follows:

• 3274 Operator - Performsinitial problem isolation and
recording of 3274 status indications by following the
procedure in the 3274 Problem Determination Guide,
GA27-2854. If the problem involves other than a customer operating procedure or customer-supplied power,
the operator completes the 3274 Problem Report Form
and requests IBM service.

• Product Customer Engineer - Performs the maintenance
procedures described in this manual to Isolate the problem to a field replaceable unit (FRU). The 3274 Problem Report Form prepared by the operator gives the
3274 indications necessary for performing these procedures. If the problem cannot be isolated and corrected,
the Product Customer Engineer requests assistance from
the next level of the support structure.
• Support Customer Engineer - Verifies the results
obtained by the Product Customer Engineer and thoroughly analyzes the problem by means of the following:

IBM has prepared this maintenance manual for the use of IBMcustomer engineers in· the installation, maintenance, or repair of the
specific machines indicated. IBM makes no representations that it
is suitable for any other purpose.
It is possible that this material may contain reference to, or information about, I BM products (machines and programs), programming,
or services that are not announced in your country. Such references
or information must not be construed to mean that IBM intends to
announce such IBM products, programming, or services in your
country.
Requests for IBM publications should be made to your IBM representative or to the I BM branch office serving your locality.
©Copyright International Business Machines Corporation 1978,
1979,1980,1981

This manual is organized as follows:
• Chapter 1 - Maintenance Approach and System
Overview
• Chapter 2 - Subsystem Indicators, Symbols, and
Messages
• Chapter 3 - Subsystem Error Logs and Test Formats
• Chapter 4 - Subsystem Tests, External Tests, and Subsystem Service Aids

• Tests

• Chapter 5 - Reference Data

•

• Chapter 6 - Tools and Test Equipment

Log Information

• Error Code Definitions

•

• Appendix B - Models A, B, C, and D Error Codes

Result of Host Test Routines

• Special Tools and Test Equipment
If the problem cannot be isolated and resolved using these
service aids, the Support Customer Engineer records the
problem indications and supporting information on the
3274 Problem Checklist and requests assistance from the
next level of the support structure.

Fourth Edition (March 1981)
This is amajor revision of, and obsoletes. SY27-2512-2. The drawings and specifications contained herein shall not be reproduced in
whole or in part without written permission.

Organization

Appendix A - Support Structure Information Form

• Appendix C - Structured Field and Attribute Processing
(SFAP) Data Stream Error Extensions
• Appendix D - Abbreviations

Federal Communications Commission (FCC) Statement
A form for readers' comments is provided at the back of this publication. If the form has been removed, address comments to IBM
Corporation, Department 52Q, Neighborhood Road, Kingston,
N. Y. 12401. I BM may use or distribute any of the information
you supply in any way it believes appropriate without incurring
any obligation whatever. You may, of course, continue to use the
information you supply.

Warning: This equipment generates, uses, and can radiate
radio frequency- energy and, if not installed and used in
accordance with the instructions manual, may cause interference to radio communications. It has been tested and
found to comply with the rimits for a Class A computing
device pursuant to Subpart J of Part 15 of FCC Rules,
Which are designed to provide r.easonable protection against
such interference when operated in a commercial environment. Operation of this equipment in a residential area is
likely to cause interference, in which case the user at his
own expense will be required to take whatever measures
may be 'required to correct the interference.
This warning is also applicable to all attaching units produced for use in the USA that have been manufactu"red
after December 31, 1980. A notice of compliance has been
affixed within the customer access area of all affected units.

Contents
Chapter
1.1
1.2
1.2.1
1.2.2
1.2.3

1. Maintenance Approach and System Overview 1-1
Maintenance Approach 1-1
Subsystem Data Flow 1-2
IML Test Data Path 1-2
IML of Unit Code 1-2
Message Data Flow between 3274 Control Unit and
Attached Devices 1-3
1.2.4
Message Data Flow between 3274 Control Unit and
Host System 1-3
1.2.5
Status, Error, and Log Data Flow 1-4
1.3
. Subsystem Functions 1-5
1.3.1
Control Unit Power-On Reset 1-6
1.3.2
Keystroke Handling 1-6
Sending to Host 1-8
1.3.3
1.3.4 \
Receiving from Host 1-8
1.3.5
Error Handling and Logging 1-8
1.3.6
Internal Testing 1-8
1.3.7
Function Priority 1-8
1.3.8
Local Channel Data Flow 1-9
1.3.9
Type A Adapter Coax Data Path 1-10
1.4
Supporting Publications 1-10

Chapter 2. Subsystem Indicators, Symbols, and Messages 2-1
2.1
Introduction 2-1
2.2
842 1 Indicators 2-1
2.3
DC ON Indicator 2-1
2.4
ONLINE/OFFLINE Indicator and Switch for Models A,
B, and D 2-2
Model A 2-2
2.4.1
Models Band D 2-2
2.4.2
Operator Information Area Layout 2-3
2.5
Readiness and System Connection Symbols 2-3
2.5.1
Do Not Enter (Input Inhibited) Symbols 2-4
2.5.2
Communication Reminder Symbol 2-5
2.5.3
2.5.4
Shifts and Modes Symbols 2-5
2.5.5
Printer Status Messages 2-5
2.5.6
Machine Check Numbers 2-5
Program Check Numbers 2-5
2.5.7
2.5.8
Communication Check Numbers 2-5
Chapter 3. Subsystem Error Logs and Test Formats 3-1
3.1
Introduction 3-1
3.2
Test 0: Communication Path Test and 3278 Display
Test 3-1
Description 3-1
3.2.1
Procedure for Requesting Test 0 3-1
3.2.2
Test 1: OveiView 3-1
3.3
3.3.1.
Test 1 Device Logs 3-2
3.3.2
Test 1 Host Adapter Logs 3-2
3.3.3
Test 1 Common Communications Adapter (CCA) Log
for BSC 3-3
3.3.4
Test 1 Common Communications Adapter (CCA) Log
and High-Performance Communications Adapter (HPCA)
Log for SDLC 3-6
3.3.5
Test 1 Local Channel Attachment (Model A) Log 3-9
3.3.6
Test 1 Local Host Attachment (Models B and D) 3-10
3.3.6.1 Model B 3-10
3.3.6.2 Model D 3-10
3.3.7
Test 1 Device Adapter Logs 3-11
3.3.8
Test 1 Type A Adapter Log 3-11
Test 1 Type B Adapter Log 3-12
3.3.9
3.3.10
Control Logic Error Log 3-12
3.4
Test 2: Display Configuration Information 3-12

3.5
3.6
3.7
3.7.1
3.7.2
3.8
3.9
3.10
3.10.1
3.10.2

Chapter S. Reference Data 5-1
5.1
Introduction 5-1
5.2
Control Unit Command Summary 5-1
5.2.1
Write 5-1
5.2.2
Erase/Write 5-1
5.2.3
Erase/Write Alternate 5-1
5.2.4.
Erase All Unprotected 5-1
5.2.5
Read Buffer 5-1
5.2.6
Read Modified 5-1
5.2.6.1 Read Modified Read 5-1
5.2.6.2 Short Read Read 5-1
5.2.6.3 Test Request Read [Models B, C (BSC), and D)
5-1
5.2.7
Read Modified All (SNA Only) 5-1
5.2.8
No Operation (Models B and D Only) 5-1
5.2.9
Select (Models Band D Only) 5-1
5.2.10
Sense (Models Band D Only) 5-1
5.2.11
Copy [Model C (BSC»)
5-1
5.3
Control Unit Order Summary 5-1
5.3.1
Set Buffer Address (SBA) 5-1
5.3.2
Start Field (SF) 5-1
5.3.3
Insert Cursor (IC) 5-1
5.3.4
Repeat to Address (RA) 5-2
5.3.5
Erase Unprotected to Address (EUA) 5-2
Program Tab (PT) 5-2
5.3.6
5.3.7
NewLine (NL) 5-2
5.3.8
End of Message (EM) 5-2
5.3.9
Duplicate (DUP) 5-2
5.3.10
Field Mark (FM) 5-2
5.3.11
Forms Feed (FF) (3262,3287,3288, and 3289
Printers) 5-2
5.3.12
Suppress Index (SI) (3288) 5-2
5.3.13
Carriage Return (CR) (3262,3287 with 3274/3276
Attachment, and 3289 Printers) 5-2
5.4
I/O Interface Codes 5-2
5.4.1
Examining 3278 Attributes and Modified Data Tags 5-6
5.4.2
Examining 3279 Attributes and Modified Data Tags 5-6
5.5
Sequence/Response Diagrams, Models A, B, and D 5-8
5.6
Status and Sense Byte Dermitions 5-9
5.6.1
Description 5-9
5.6.2
Error Recovery Procedures 5-12
5.7
Sequence/Reponse Diagrams, Model C, BSC 5-13
5.8
Remote Status and Sense Byte Definitions, Model C,
BSC 5-18
5.8.1
Error Recovery Procedures, Model C, BSC 5-20
Supplementary Procedures 5-21
5.8.2
Model A, Local Attachment (SNA Version) 5-21
5.9
Commands 5-21
5.9.1
5.9.1.1 Write Command 5-21
5.9.1.2 Read Command 5-21
5.9.1.3 No Operation Command 5-21
5.9.1.4 Sense Command 5-21
5.9.1.5 Control Command 5-21
5.9.1.6 Write Break Command 5-22
5.9.1.7 Write Start 0 Command 5-22
5.9.1.8 Read Start 0 Command 5-22
5.9.1.9 Write Start 1 Command 5-22
5.9.1.10 Read Start 1 Command 5-22
5.9.1.11 Restart Reset Command 5-22
5.9.1.12 Sense ID Command 5-22
Status and Sense Definitions 5-22
5.9.2

Test 3: Display the Status of All Configured Terminals
and Display the Control Unit Summary Counters 3-13
Test 4: Reset Any Test 1 Log 3-14
Test 6: Device Control Block Display 3-14
Test 6 Byte Identification 3-14
DCB Bit Definitions 3-15
Test 7: Dynamic Convergence (Color) 3-16
Test 8: PS, Highlighting, and Color 3-16
3277 Path Test and Test Request Key 3-16
BSC or Local Host Attached 3-16
SNA Attached 3-16

Chapter 4. Subsystem Tests, External Tests, and Subsystem Service
Aids 4-1
4.1
Introduction 4-1
4.2
Initial Machine Load (lML) Tests 4-1
ALT 1 IML Mode 4-1
4.2.1
ALT 2 IML Mode, Model C with Wrappable Modem
4.2.2
(Test/Operate Switch in Operate Position) 4-1
ALT 2 IML Mode, Model C without Wrappable Modem
4.2.3
(Test/Operate Switch in Test Position) 4-1
ALT 2 IML Mode, Model A Local Channel
4.2.4
Attachment 4-2
ALT 2 IML Mode, Model B Local Host Attachment 4-2
4.2.5
ALT 2 IML Mode, Model D Local Host Attachment 4-2
4.2.6
ALT 2 IML Mode, Modem Self-Test for Model C with
4.2.7
Greater than 1200-bps Integrated Modem 4-2
Local Model A Display System Online Tests
4.3
(T3274B) 4-2
Purpose 4-2
4.3.1
Applicable Executive Control Programs 4-2
4.3.2
Composite Error Message Description 4-3
4.3.3
4.3.4
OLT Routines 4-3
4.3.5
CDS Card Format, Model A 4-3
Local Models Band D Display System Online 4-3
4.4
Purpose 4-3
4.4.1
Applicable Executive Control Programs 4-3
4.4.2
Composite Error Message Description 4-4
4.4.3
4.4.4
OLT Routines 4-4
4.4.5
CDS Card Format, Models Band D 4-4
Model. C Display System Online Tests 4-4
4.5
Purpose 4-4
4.5.1
Applicable Executive Control Programs 4-4
4.5.2
Model C Online Tests 4-4
4.5.3
Serviceability Aids 4-5
4.6
Monitoring of EIA Interface Lines (Model C) 4-5
4.6.1
4.6.2
Monitoring of Bus/Tag Interface Lines (Models A, B, and
D) 4-5
4.6.3
Isolate Feature Board 01A-A2 4-5
Diskette Patching Procedure 4-5
4.6.4
Dump Procedure 4-6
4.6.5
BackupSystem Diskette Generation 4-6
4.6.6
Display Customizing Responses 4-.6
4.6.7
Coax Cables (hand I) 4-6
4.6.8
4.6.8.1 Cable h (Indoor) 4-6
4.6.8.2 Cable I (Outdoor) 4-6
4.6.8.3 Coax Cable Splicing 4·6
Coax Testing with Scope 4-6
4.6.9
4.6.9.1 Testing for Discontinuities 4-7
4.6.9.2 Setup and Test Procedures 4-7

SY27-2512-3

59.2.1
5.9.2.2
5.9.3
5.9.3.1 '
5.9.3.2
5.10
5.10.1
5.10.1.1
5.10.1.2
5.10.2
5.10.2.1
5.10.2.2
5.10.3
5.11
5.11.1
5.11.2
5.11.3
5.11.4
5.11.5
5.11.6
5.12
5.12.1
5.12.2
5.12.3
5.12.4
5.12.5

Status Bits
5-22
Sense Bits 5-23
Error Recovery Procedures 5-24
Model-A-Detected Errors 5-24
Channel-Detected Errors 5-24
SDLC Sequence/Response Descriptions 5-24
SDLC Transmission Frames 5-24
Response Modes 5-24
Control Field 5-24
Sequence Error Recovery Procedures 5-25
Abort Function 5-25
Timeout Controls 5-25
Hexadecimal Notation and Frame Summary 5-25
SNA Information 5-25
Session Control 5 -25
Data Flow Control 5-25
Transmission Header 5-26
Request/Response Header 5-26
SNA Definitions 5-27
SDLC/SNA Command to Start a Session 5-27
SDLC/SNA Error Information 5-28
Exception Response with Sense Data Included 5-28
SNA Sense Codes 5-28
Logical Unit Status (LUSTAT) 5-29
Command Reject 5-30
Request Maintenance Statistics (REQMS)
Command 5-30
5.12.5.1 Record Formatted Maintenance Statistics
(RECFMS) 5-30
5.12.5.2 RECFMS Formats 5-31
5.13
Switches and Controls 5-31
BSC and SNA Readiness Symbols 5-32
5.14
5.15
Digital Data Service (DDS) Adapter 5-34
Chapter 6. Tools and Test Equipment 6-1
6.1
Introduction 6-1
6.2
Buffered Teleprocessing Diagnostic {\.nalyzer and
Tester 6-1
6.3
NU Data Tester 6-1
6.4
Maintenance Device 6-1
6.5
PT-2 Attachment to Non-EIA Interfaces 6-1
Appendix A. Support Structure Information Form A-I
Appendix B. Models A, B, C, and D Error Codes B-1
Appendix C. Structured Field and Attribute Processing (SF AP)
Data Stream Error Extensions C-l
Appendix D. Abbreviations D-1

iii

SY27-2512-3

Figures
Figure 1-1.
Figure 1-2.
Figure 1-3.
Figure 1-4.
Figure 1-5.
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

1-6.
1-7.
1-8.
1-9.
1-10.
1-11.
1-12.
1-13.
2-l.
2-2.
2-3.

Figure 2-4.
Figure 2-5.
Figure 2-6.
Figure
Figure
Figure
Figure

2-7.
2-8.
2-9.
3-1.

Figure 3-2.
Figure 3-3.
Figure 3-4.
Figure 3-5.
Figure 3-6.
Figure 3-7.
Figure 3-8.
Figure 3-9.
Figure 3-10.
Figure 3-11.
Figure 3-12.
Figure 3-13.
Figure 3-14.
Figure 3-15.
Figure 3-16.
Figure 4·J.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5.

Support Customer Engineer Maintenance
Approach 1-1
3274 Subsystem Overview 1-2
Initial Machine Load Data Flow 1-2
Message Data Flow between 3274 Control Unit and
Devices 1-3
Message Data Flow between 3274 Control Unit and
Host System 1-3
Status, Error, and Logic Data Flow 1-4
3274 Subsystem Functions 1-5
Keystroke Handling, Type A Adapter 1-7
Inbound Messages 1-8
Outbound Messages 1-8
3274 Subsystem Functional Priorities 1-8
Local Channel Attachment Data Flow 1-9
Coax to Type A Adapter Data Flow 1-10
842 1 Indicator Control Logic 2-1
ONLINE/OFFLINE Control Logic, Model A 2-2
ONLINE/OFFLINE Control Logic, Models Band
D 2-2
Operator Information Area Layout 2-3
Readiness and System Connection Symbols
(Locations 1 through 6) 2-3
Do-Not-Enter Symbols (Locations 9 through
17) 2-4
Reminders (Locations 21 through 27) 2-5
Shifts and Modes (Locations 37 through 41) 2-5
Printer Status (Locations 60 through 64) 2-5
Summary of Counter Definitions by Device Log
Type 3-2
CCA BSC Operation Attempted Chart (Code FF) 3-3
CCA BSC Operation Ending Chart (Code CCCC)
(2 parts) 3-4
Sense Byte Breakdown Chart for CCA BSC (Code
SSSS) 3-6
CCA/HPCA SDLC Operation Attempted Chart
(Code FF) 3-6
CCA/HPCA SDLC Operation Ending Chart (Code
CCCC) 3-7
Sense Byte Breakdown Chart for CCA/HPCA SDLC
(Code SSSS) 3-8
3274 Model A Attachment Information Breakdown
Chart 3-9
3274 Model B Operation Attempted Chart (Code
RR) 3-10
HH Byte Definitions 3-10
Sense (SS) Byte Definitions 3-11
Type B Adapter Operation Attempted Chart (Code
FF) 3-12
Type B Adapter Operation Ending Chart (Code
CCCC) 3-12
Subsystem Configuration (2 parts) 3-12
Test 6 Byte ID Chart 3-14
DCB Bit Definition Chart (2 parts) 3-15
IML Test Error Indications 4-1
ALT 1 IML Sequence 4-1
AL T 2 IML Sequence, Model C with Wrappable
Modem 4-1
ALT 2 IML Sequence, Model C without Wrappable
Modem 4-1
ALT 2 IML Sequence, Model A Local Channel
Attachment 4-2

Figure 4-6.
Figure 4-7.
Figure 4-8.
Figure 4-9.
Figure 4-10.
Figure 4-11.
Figure 4-12.
Figure 4-13.
Figure 4-14.
Figure 4-15.
Figure 4-16.
Figure 4-17.
Figure 4-18.
Figure 4-19.
Figure 4-20.
Figure 4-21.
Figure 4-22.
Figure 5-1.
Figure 5-2.
Figure 5-3.
Figure 5-4.

Figure 5-5.

Figure 5~6.
Figure 5-7.
Figure 5-8.
Figure 5-9.
Figure 5-10.
Figure 5-11.
Figure 5-12.
Figure 5-13.
Figure 5-14.
Figure 5-15.
Figure 5-16.
Figure 5-17.
Figure 5-18.
Figure 5-19.
Figure 5-20.
Figure 5-21.
Figure 5-22.
Figure 5-23.
Figure 5-24.
Figure 5-25.
Figure 5-26.

ALT 2 IML Sequence, Model B Local Host
Attachment 4-2
ALT 2 IML Sequence, Model D Local Host
Attachment 4-2
AID2 Card Indicator for 2400-bps Integrated
Modem 4-2
AID2 Card Indicator for 4800-bps Integrated
Modem 4-2
AID2 Card Indicator for 9600-bps Integrated
Modem 4-2
Example of Maximum Configuration of Error
Message Content, Model A 4-3
T3274B OLT Routines 4-3
CDS Card Format, Model A 4-3
Example of Maximum Configuration of Error
Message Content, Model B 4-4
T3274A OLT Routines 4-4
CDS Card Format, Models Band D 4-4
3274 Model C Online Tests 4-4
Operator Codes 4-6
Incident and Reflected Waves 4-7
Scope Setup 4-7
Measurement Points 4-7
Display Examples (2 parts) 4-8
Command Codes 5-1
Buffer Control Orders and Order Codes 5-2
United States EBCDIC I/O Interface Code for 3274
Control Unit and Attached 3277 Display Stations 5-3
United States EBCDIC I/O Interface Code for 3274
Control Unit and Attached 3262, 3278, 3279, 3287,
and 3289 Terminals 5-3
United States ASCII I/O Interface Code for 3274
Control Unit and Attached 3262, 3278, 3279, 3287,
and 3289 Terminals 54
Format of Write Control Character (WCC) Byte 5-4
Function of Write Control Character (WCC) Bits 54
Format of Copy Control Character (CCC) Byte 5-4
Function of Copy Control Character (Ccq Bits 5-4
Buffer Transfers for 3274 Model C (BSC) Copy
Command Operation 5-5
Attention ID (AID) Configurations 5-5
Attribute Character Bits 5-6
3278 Top-Card Connector CE Jumper (Three Base
Cards) 5-6
3278 Top-Card Connector CE Jumper (Two Base
Cards) 5-6
3279 Top-Card Connector CE Jumper 5-6
3279 Base Field Attributes 5-6
Extended Field and Character Attributes 5-7
Attribute Character Bit Assignments for 3277s 5-7
Control Character I/O Codes 5-7
Initial Selection 5-8
Write - After Selection with Write Command 5-8
Read - After Selection with Read Command 5-8
Sense - After Selection with Sense Command (Issued
in Response to Unit Check Status) 5-8
Status Byte Bit Assignments for 3274 Models Band
D 5-9
Sense Bit Description 5-9
Initial Status and Sense Conditions for 3274 Models
Band D 5-10

Figure 5-27. Ending Status and Sense Conditions for 3274 Models
Band D 5-10
Figure 5-28. Asynchronous Status and Sense Conditions for 3274
Models Band D 5-11
Figure 5-29. General Poll and Specific Poll, Sequence/Response
Diagram 5-13
Figure 5-30. 3274 Message Response to Polling or Read Modified
Command 5-14
Figure 5-31. Selection Addressing, Sequence/Response
Diagram 5-15
Figure 5-32. Write-Type a~d Control-Type Commands, Sequence/
Response Diagram 5-16
Figure 5-33. Read-Type Command, Sequence/Response
Diagram 5-17
Figure 5-34. Remote Status and Sense Byte Definitions, BSC 5-18
Figure 5-35. Remote Error Status and Sense Responses, BSC 5-19
Figure 5-36. Remote 3270 BSC Status and Sense Conditions 5-20
Figure 5-37. 3274 Model A Local Command Codes 5-21
Figure 5~38. Status Definitions 5-22
Figure 5-39. Sense Definitions 5-22
Figure 5-40. Status Bit Conditions 5-22
Figure 541. Sense Bit Conditions 5-23
Figure 5-42. Initial Status and Sense Conditions, 3274 Model
A 5-23
Figure 5-43. Ending Status and Sense Conditions, 3274 Model
A 5-23
Figure 5-44. Asynchronous Status and Sense Conditions, 3274
Model A 5-24
Figure 5-45. Nonsequenced Commands and Responses Supported
by 3274 5~25
Figure 5-46. SDLC Commands and Responses in Hexadecimal
Notation 5-25
Figure 5-47. Session Control Functions Supported by 3274 5-25
Figure 5-48. Data Flow Control Requests Supported by 3274 5-25
Figure 5-49. Transmission Header Format 5-26
Figure 5-50. Request/Reponse Header Format 5-26
Figure 5-51. SDLC/SNA Commands Required to Start Session with
LU2 5-27
Figure 5-52. SDLC/SNA Exception Responses 5-28
Figure 5-53. Summary Table of LUSTATs 5-30
Figure 5-54. Command Reject (CMDR) Message Format 5-31
Figure 5-55. Switch and Control Explanation 5-31
Figure 5-56. BSC Readiness Symbols 5-32
Figure 5-57. SNA Readiness Symbols 5-33
Figure 5-58. Connection of 3274 Control Unit Model C with
DDS Adapter Feature 5-34
Figure 5-59. Digital Data Wave shapes 5-34
Figure 6-1. TPLM Tab Pin Locations 6-1

CE Safety Practices
All Customer Engineers are expected to take every safety
precaution possible and observe the following safety practices while maintaining I BM equipment:
1. Do not work alone under hazardous conditions or
around equipment with dangerous voltage. Always
advise your manager if you MUST work alone.
2. Remove all AC and DC power when removing or
assembling major components, working in immediate
area of power supplies, performing mechanical
inspection of power supplies and installing changes in
machine circuitry. Pull the power plug from the
receptacle to remove power source.
3. Wall box power switch, when used to disconnect power,
should be locked or tagged in off position. "Do not
Operate" tags, form 229-1266, should be securely
attached to power switch or to outside of power box.
4. When it is absolutely necessary to work on equipment
having exposed operating mechanical parts or exposed
live electrical circuitry anywhere in the machine, the
following precautions must be followed:
a. At least one other person familiar with power-off
controls, emergency power-off procedures, and the
location of the wall box power switch, must be in
the immediate vicinity at all times.
b. Never wear rings, wrist watches, chains, bracelets,
metal cuff links, etc.
c. Use only insulated pliers and screwdrivers.
d. Keep one hand in pocket.
e. When using test instruments be certain they are of
proper capacity and controls are set correctly. Use
only insulated probes.
f. Avoid contacting ground potential (metal floor
strips, machine frames, etc.; use suitable rubber
mats, purchased locally if necessary).
5. Safety Glasses must be worn when:
a. Using a hammer to drive pins, riveting, staking, etc.
b. Power hand drilling, reaming, grinding, etc.
c. Using spring hooks, attaching springs.
d. Soldering, wire cutting, removing steel bands.
e. Using solvents, sprays, cleaners, chemicals, etc., to
clean parts.
f. All other conditions that may be hazardous to your
eyes. REMEMBER, THEY ARE YOUR EYES.
6. Special safety instructions such as handling Cathode
Ray Tubes and extreme high voltages must be followed
as outlined in CEMs and Safety Section of the Maintenance Manuals.
7. Do not use solvents, chemicals, greases or oils that have
not been approved by IBM.
8. Avoid using tools or test equipment that have not been
approved by IBM.
9. Replace worn or broken tools and test equipment.
10. The maximum load to be lifted is that which in your
opinion and that of management does not jeopardize
your own health or well-being or that of other
employees.
11. All safety devices such as guards, shields, signs, ground
wires, etc., shall be restored after maintenance.
12. Each Customer Engineer is responsible to ensure that no
action on his part renders a product unsafe or exposes
hazards to customer personnel.
13. Place removed machine covers in a safe, inaccessible
place where no one can trip over them.
14. All machine covers must be in place before machine is
returned to customer.
15. Always place CE tool kit away from walk areas
(Le., under desk or table) where no one can trip over it.
16. Avoid touching mechanical moving parts (when lubricating, checking for play, etc.).
17. When using stroboscope, do not touch ANYTHING it may be moving.

18. Avoid wearing loose clothing that may be caught in
machinery. Shirt sleeves must be left buttoned or
rolled above the elbow.
19. Ties must be tucked in shirt or held by a tie clasp
(preferably nonconductive) approximately 3 inches
from end. Tie chains are not recommended.
20. Before powering up or starting equipment, make
certain other CEs and customer personnel are not in
a hazardous position.
21. Maintain good housekeeping in area of machines while
performing and after completing maintenance.
22. Even though preventive measures are taken, accidents
do occur. CEs and support personnel should be prepared to follow emergency first aid procedures as
outlined below.
First Aid - General
1. If accidental electrocution occurs:
a. Remove power source before touching victim.
b. If power cannot be removed, pull victim away from
equipment by using non-conductive material such as
a broom handle, leather belt, or necktie.
c. Immediately begin rescue breathing (see below).
d. Begin CPR if necessary and only if trained person is
available.
e. Call a doctor - Have someone summon medical aid.
f. Remain in position - After victim revives, be ready
to resume respiration if necessary.
2. For serious injury:
a. Summon medical aid.
b. Do not move victim unless absolutely necessary to
remove from danger.
c. Attempt to stop serious bleeding by using pressure
points or a pressure bandage.
d. Loosen clothing and keep victim warm.

Artificial Respiration
General Considerations
1. Start immediately - seconds count.
Do not wait or look for help or stop to loosen clothing.
Warm the victim or apply stimulants.
2. Check mouth for obstructions; remove foreign objects;
pull tongue forward.
Rescue Breathing for Adults - Place
Victim on His Back Immediately
1.
2.
3.
4.
5.
6.
7.

Clear throat of water, food, or foreign matter.
Tilt head back to open air passage.
Lift jaw up to keep tongue out of air passage.
Pinch nostrils to prevent air leakage when you blow.
Blow until you see chest rise.
Remove your lips and allow lungs to emp~y.
Listen for snoring and gurglings, signs of throat
obstruction.
8. Repeat mouth-to-mouth breathings 10-20 times a
minute. Continue rescue breathing until he breathes
for himself, or medical aid arrives.

~ ~inal mouth-

Thumb and
.' .
finger positions

to-mouth
_posi"tion

Reprint Courtesy Mine Safety Appliances Co.

SY27-2512-3

•

Chapter 1. Maintenance Approach and System Overview'

This chapter contains information to assist the support
customer engineer in isolating and correcting 3274 subsystem problems that cannot be attributed to a failing
field replaceable unit (FRU). The information supplements
existing documentation covering problem isolation, use of
serviceability aids, specialized tools, and test equipment.
The topics presented include the following:
•

Overall Maintenance Approach: The maintenance

approach is outlined to provide flexibility both in the
type of approach taken and in the selection of supporting serviceability aids. The maintenance approach
identifies and refers to procedures, tests, specialized
tools, and test equipment that will most likely help
isolate various types of 3274 problems. Detailed descriptions of these serviceability aids and their use are contained in other chapters in this publication. In addition,
examples using these serviceability aids are given for
typical 3274 problems.
• Subsystem Operation Overview: This overview gives a

general description of 3274 operations and functions.
• Serviceability Aids: A general description of service·

ability aids and their use is given. These aids include the
operational indicators, display symbols, error suffix
codes, logouts, tests, test equipment, and host error
recording.
•

•

Reference Material: All supporting reference material in
this publication is identified and described. This reference material provides detailed descriptions of error
recording and indications, tests, error recovery procedures, 3270/3274 operational differences, error suffix
code action chart, and tools and test equ ipment.

Review/Verify
Results Obtained
by the Product
Customer Engineer

Material
3274 Problem Report Form

•

Material

Analyze:
•
•
•

Step 1
Review and verify the results obtained by the product customer engineer by using the following reference material:

Perform Isolation Procedure

Step 2

The suggested maintenance approach identifies and refers
to various procedures, tests, tools, and test equipment
that will most likely aid in isolation of the problem. This
approach has four basic steps, which are performed in
sequence:

• 3274 Control Unit Maintenance Information

Complete If Necessary

3274 Maintenance Information

•

Chapter 2. Subsystem Indicators, Symbols,
and Messages
- Chapter 3. Subsystem Error Logs and Test
Formats
Chapter 4. Subsystem Tests, External Tests,
and Subsystem Service Aids
Chapter 5. Reference Data

Operational
Indicators
Display Symbols
Error Suffix
Codes

Problem Isolated
and

I
I

Corrected

I
I

Analyze:

Step 2

•
•
•

Analyze operational indicators (842 1), display symbols,
and error suffix codes (nnn codes).

_-.J

Logouts
Hang Conditions
Failing Sequence

Step 3
Analyze logouts, hang conditions, and failing operation
sequences.

Step 4

Assistance Preparation
• Record Symptoms
• Complete the Support
Structure Information
Form
• Contact the next level
of the support structure
for assistance.

Record all problem symptoms, and complete the Support
Structure Information Form in preparation for requesting
assistance. The effectiveness of the assista'nce wi II depend
largely on the information that you provide.

Supporting Publications: Supporting I BM publications

are identified, and their contents briefly described.
•

Step 1

indications and the type of operation being performed at
the time the error occurred. Therefore, the maintenance
approach to typical problems described in the following is
not necessarily the only effective approach that could be
used.

• 3274 Problem Report Form

•

These four steps are illustrated in Figure 1-1.

Procedure for Requesting Assistance: A procedure for

requesting assistance from the next level of the support
structure is outlined. This procedure includes 3274
problem recording which will aid the support structure
in problem determ ination.

Perform Mach ine
Checkout MAP 100
(in the 3274 MIM) to
Verify Correct
OperationlReturn
3274 to Customer

1.1 MAINTENANCE APPROACH
This maintEmance approach is outl ined to provide flexibility both in the type of approach taken and in the selection
of supporting service aids. The approach used to isolate a
specific 3274 problem may vary because of multiple error

Effective assistance will
depend largely on complete and accurate
recording of problem
symptoms, and on
completion of the
Support Structure
Information Form.
See Appendix A.

The Support Structure
will assist you in problem determination.
This assistance may
include:
•
•
•

SymptomlFix Search
Special Testing
Equipment
On-Site Assistance

Figure 1-1. Support Customer Engineer Maintenance Approach

SY27-2512-3

1-1

SY27-2512-3
1.2 SUBSYSTEM DATA FLOW
The 3274 subsystem data flow consists of test data, control data (unit code); status, error, and log data;·and message data between the components of the subsystem.
Figure 1-2 ill~strates the 3274 subsystem configuration.
The data flow is described as follows:
•

•

Initial Machine Load (lML) of Test Data - Loading the
1M L test data residing on the system diskette into control storage (paragraph 1.2.1 and Figure 1-3).
Initial Machine Load (lML) of Unit Code - Loading the
unit code residing on the system diskette into control
storage (paragraph 1.2.2 and Figure 1-3).

• Message Data Flow between 3274 Control Unit and
Attached Devices - The flow of message data between
the 3274 Control Unit and attached devices (paragraph
1.2.3 and Figure 1-4).
• Message Data Flow between 3274 Control Unit and Host
System - The flow of message data between the 3274
Control Unit and the host system (paragraph 1.2.4 and
Figure 1-5).
• Status, Error, and Log Data Flow - The flow of data
from the 3274 Control Unit, the host system, and
attached devices to the data control block area of control storage (paragraph 1.2.5 and Figure 1-6).

Remote Attachment
3274 Model C

Control Logic

I HPCA

1-2

1.2.1 IML Test Data Path

1.2.2 1M L of Unit Code

The IML test data path is shown in Figure 1-3. IML test
data is retrieved from the 33FD after IML tests 0000, 0001,
and 0002 have been successfully completed. IML test 0002
verifies that the 33FD and the 33FD adapter are functionally operational. The data path, from origin to destination,
is identified as follows:

The data path of IML (loading of unit code) is the same as
the IML test data path. Unit code is normally loaded after
the IML tests have been successfully completed. Placing
the ALT switch in the AL T 1 position and pressing the 1ML
pushbutton will cause the IML test to be bypassed and initiate loading of the unit code.

•

33FD

•

33FD Adapter

• Bus
• Control logic
• Control storage

SNA/SDLC

Remote Attachment
3274 Model C

Control Logic

HPCA

CCA

Local Channel Attachment
3274 Model A

SNA
Version

Control
Storage

t:;:!=::Lt::!=~ )

BSC
Control Code
Area

33FD

Host
System

Host
System
Local Channel Attachment
3274 Model A
SNA
Version

Channel

Local Host Attachment
3274 Models Band D
3272
Version

Channel

33FD
Adapter
Category A
Devices
Type.A
Adapter

13262
13289
3287
3278/3279

Channel

33FD
Adapter
Category A
Devices
~~~--,

Type A
Adapter

Category B
Devices

I 3287/3288
3284/3286

Category B
Devices

3277

Type B
Adapter

Figure 1-2. 3274 Subsystem Overview

CCA

Local Host Attachment
3274 Models Band D

3272
Version

CCA

BSC

Control
Storage

SNA/SDLC

Figure 1-3. Initial Machine Load Data Flow

3287/3288
3284/3286
3277

•

1.2.3

Message Data Flow between 3274 Control
Unit and Attached Devices

Message data flow between the 3274 Control Unit and
attached devices is shown in Figure 1-4. The message data
paths, from origin to destination, are identified as follows:

3274 Control Unit
to Device

Device to 3274
Control Unit

1.2.4

•

• Category A or B device

Message data flow between the 3274 Control Unit and the
host system is shown in Figure 1-5. The message data paths,
from origin to destination, are identified as follows:

Control storage
(message buffer area)

• Control logic

• Category A or B device

Controi Logic

"
~

• Control logic

• Control storage
(message buffer area)

1 HPCA·.

CCA

:::I

SNA
Version

M.ss.ge Buff.,
Area

.,.

, ....

Channel

Host
System

Local Channel Attachment
3274 Model A
SNA
Version

3272

Channel

Version

Local Host Attachment
3274 Models Band D

3272
Version
~

,
Type A
Adapter

13262
Category A 13289
Devices
'3287
3278/3279

33FD

I-

Type B
Adapter

Channel

...-

13282

Category A 13289
Devices
J3287
Type A
Adapter

3278/3279

Category B 13287/3288
Devices
I 328413286
3277
Type B
Adapter

Unit and Devices

----

33FD
Adapter

Category B I 3287/3288
Devices
I 3284/3286;
3277

~ntrol

• Bus
• Control logic
• Control storage
(message buffer area)

Host system

CCA

Local Host Attachment
3274 Models Band D

Flow between 3274

Bus
Remote host adapter/
local channel attachment
or local host attachment

BSC

)
r.r_~
I~~

D~ta

Remote host adapter/
local channel attachment or local host
attachment

Control
Storage
Host
System

Local Channel Attachment
3274 Model A

Figure 1-4. Message_

•

• Control logic

SNA/SDLC

BSC

33FD
Adapter

Host system

Remote Attachment
3274 Model C

Control Logic

CCA

33FD

•

M.".ge
Buffer

• Control storage
(message buffe~ area)

•

'~"
Area

Host to 3274
Control Unit

•
•

Control
Storage

)

3274 Control Unit
to Host

SNA/SDLC

I HPCA
CCA

Type A or B adapter

• Bus

• Bus
• Type A or B adapter

Remote Attachment
3274 Model C

•

Message Data Flow between 3274 Control
Unit and Host System

Figure 1-5. Message

SY27 -2512-3

D~ta

Flow between 3274 Control Unit and Host System

1-3

SY27-2512-3
1.2.5 Status, Error, and Log Data Flow
Status. error, and log data flow is shown in Figure 1-6. The
data paths, from origin to destination. ate identified as.
follows:
Host System

•

Category A and B Devices 33FD

Remote host
•
adapter Ilocal
channel attachment or local
host
attachment

Type A or B adapter

•

33FD adapter

Remote Attachment
3274 Model C

Control Logic

IHPCA

SNA/SDLC

CCA
I-

Control
Storage

1-4

BSC

)

CCA

S;
,

•

Bus

•

Control logic

•

Control storage
(control block area)

Host
System

Local Channel Attachment
3274 Model A

SNA
Version

Channel

Local Host Attachment
3274 Models Band D
3272
Version

33FD

Channel

33FD
Adapter
13262
Category A I 3289
Devices
13287
Type A
Adapter

Type B
Adapter

Figure 1-6. Status. Error. and Logic Data Flow

3278/3279
I-

Category B 13287/3288
Devices
J 3284/3286
3277

.....
f-

I-

The following functions are provided by the 3274 subsystem:

Control
Storage

Description

, Function

1.3 SUBSYSTEM FUNCTIONS

Machine check/program check activity
I/O operations to and from the host CPU

33FD operations

I/O operations to and from Category A and
Category B devices

Device feature functions

Messages sent to the host CPU

Messages received from the host CPU

Initialization (POR and IML)

The 3274 subsystem functions are illustrated in Figure 1-7.
The functions of the 3274 may be grouped into.six basic
categories: (1) Power On Reset (POR) operations, (2) keytracking (moving data from the keyboard to the display
screen), (3) receiving from the host, (4) sending to the host,
(5) error handling and logging, and (6) internal testing.

Control Logic 1

Host

Bus

Function 52
Messages Going to
Host CPU

Function 0
Machine Check and
Program Check Activity

Function

I/O Operations to
and from Host CPU
Function 6 2

Function 7

Messages Received
from Host CPU

Power On Reset (POR)
and Initial Machine
Load (IML) Operations

Function 4 2
Device Feature Functions
(MSR, etc.l

Function 3 2
I/O Operations to
and from Category A
or B Devices
- - - Messages to Host

functions shown in this diagram are
provided by the control logic.
2 Functions , through 6 reside in the control
logic; they are shown here to illustrate
their association with the adapters, devices,
and the host.

1 The

33FD
Adapter

Messages to the Device

Figure 1·7. 3274 Subystem Functions

SY27-2512-3 '

1-5

SY27·2512·3
1.3.1 Control Unit Power-On Reset
When the 3274 is powered on, the +5 V dc supply originating at the low-voltage power supply (LVPS) provides
input to the PO R circuit at LVPS card point E 15. The
POR signal is then generated to the 01 A-A 1 board as output from LVPS card point El. POR to the A1 board
generates a restart to the control logic and subsequently
starts a normal 1M L sequence.

1.3.2 Keystroke Handling
The requests and status from the attached devices are
handled ~y the Keystroke control function. When an
operator1presses a key, the keyed data is read by the display base card 1, which, if it receives a poll, sends the
data to the terminal adapter (Category A devices
only). The terminal adapter then loads the status
and scan code of the actuated key into a queue.
The terminal adapter control retrieves this infor·
mation from the buffer queue.
"Keystroke control converts the scan code and distributes
the data to the appropriate functions. See Figure 1-8 for an
illustration of Type A adapter keystroke handling.

As an example of keystroke handling, when a graphic character key is pressed, the graphic key scan code is converted
into internal code and then into regen code by means of a
language code conversion table. The converted regen code
is moved into the device regen buffer, after which the
graphic character keyed may be seen displayed on the
screen.
When a device is polled, if it has an error condition or
request from a feature (selector pen, MSR), it sends status
to the terminal adapter, and key tracking control handles
the status as it does a status preceding keyed data.
An error condition detected by the device is signaled to the
terminal adapter when the device is polled. Error conditions are (1) device check (a parity error was detected in
the regen buffer), (2) keyboard overrun (keystrokes too
close together) , and (3) feature timeout (no response from
the feature card within the expected time).
Special keyboard scan codes are used for the device POR
signal and keyboard overrun conditions. Selector-pen data
is sent to the terminal adapter by read commands. The row
count is sent on the first read, and the field count is sent
on the second.

1-6

,
To Control Logic

I/O Tags - 8421 Indicators

...

I/O Bus 0

~
...
~

Bus 0
Bidirectional
Gating

~
"
... >

To Driver/Receiver Car

....

Bus 0
Decode
and
Timings

..")

......
~

4,.

I/O Bus 1

~
- ...
~

Bus 1
Bidirectional
Gating

~2.........
~

...

L
~

..;>
..

Driver/
Receiver
Address
Decode

--..

--....

...

Transmit OSC
Receive
Clock

~
~ ~

Bus 1
Decode
and
Timings

Tag Sync
8 4 2 1 Indicators
and Miscellaneous

....

---...

Clock

....

......

Receive Data

Coax
Line
Control
Receive

...

DIR Select

Transmit Clock

Receive Data
:....
....

•

....

--r--

...

.;>

r.:!>

Data
Buffer
and
Controls

...

~V'7

....

SERDES*
Control
Poll, Read
Write
Control

SERDES*

.....

Transmit
Data

....

--..

Coax
Line
Control
Transmit

.....

Transmit Data

IV
I

.....
Bus 0

Bus 1

•
SERDES*
Decode
and
Output
Buffer

*Serializer/Deserializer
A

t!'-

....

.Figure 1-8. Keystroke Handling, Type A Adapter

SY27 -2512-3 ,

1-7

SY27 -2512-3

1-8

1.3.3 Sending to Host

1.3.4 Receiving from Host

1.3.7 Function Priority

Data from Category A devices is queued via function 3
into various buffer formats, depending on the type of
host attachment used, by the device control code. The
data is then handled, again in queued buffer formats,
by the data stream control code. The host processing
contro I code then forwards the appropriate data from
another queued buffer to the host. (See Figure 1-9.)

Data from th~ host is queued via function 1 into common
transmit/receive buffers of various formats, depending on
the type of host attachment used, by the host processing
control code. The data is then handled in queued buffer
formats by the data stream control code. The device control code then forwards the data to the device. (See
Figure 1-10.)

The priority scheme used by the 3274 subsystem is illustrated in Figure 1-11. Function 0 has the highest priority,
and function 7 has the lowest priority. For example, if a
machine check (function 0) and a 33FD operation (function 2) are both pending, the 3274 control logic performs
function 0 followed by function 2.

Input Messages from Device

r---

Function 3
Device I/O Operation

r---

Host line nterface Inbound Message

.......

Function 5

Outbound Message

~ Output Message to Host CPU

Figure 1-9. Inbound Messages

Host Adapter

Device Feature Functions
(MSR, etc.)

Function 6

Function 3
~

Function 4

Inbound Message

Function 1
Host Adapter

Function 1
r---

Function 0
Machine Check and
Program Check Activity

Function 1

Function 5

Setup Operations to
and from Host CPU

Messages Going to
Host CPU

Function 2

Function 6

33FD Operations

Messages Received
from Host CPU

Function 3

Function 7

Setup Operations to
and from Category A
or B Devices

POR Operations
and IML

I.11III.
~

Device I/O Operation

-:- Output Message to Device

Figure 1-10. Outbound Messages

1.3.5 Error Handling and Logging
Error handling and logging is performed by the control
logic and storage. Log statistics and information are
available for each device and host adapter by means of
test procedures.

1.3.6 Internal Testing
All internal tests are performed by the control logic, and
indicators are provided for test results. Host support is
not required for internal testing.

Figure 1·11. 3274 Subsystem Functional Priorities

1.3.8 Local Channel Data Flow
Figure

1~12

370

illustrates local channel data flow.

ir=>

=>
=>

370
Data
Bus

<=~

«'
'""

5·Bit
Buffer

370
4·Bit
Buffer

•

b
~

...
~ r---

¢:

370
Tags

~
K ·1-1* NC

(-)-

....
K....

Select Out
(Outgoing)

K3·1 * NC

......

•

•
•
•
•
•
•
•

~
Driver

Address
Compare

•

L,--

r--

~
"""-

r--

Set Out
CU Busy
Select Control
Po" CUE Stack

~
~

Reg

~
~

~
./

Reg

"-'---

Reg

.....

h:2

['211

Basic
Status

Bus 1

----

I--

I/O Bus 0

Bus 1

r-r--

11\s..~
... -

:---"'

•

Address
Compare

~
"

...

."L

....
....

I/O Bus 1

....~
V\:<;." ... /

'---

Disconnect
Status Control
Enable
Data Control

!--

=>
=>
~

-Driver Degate
and
Power On Reset

Reg
4

•

(Wi red Address)

Command
Decode
Control
Logic
Control

L.:>
~

~
./

...

CTR

-""""--

U
r

Data
Control

/
"-'""

...~

I/O Tag
Control

....

I/O Tags

....
...

Select Out
(Incoming)

K2-1* NO
Receiver

*Relay.Control for Select Out (on the A 1 N2 card)
Power On/Off Sequence

K3 Pick

K1 Pick
K2 Pick
Power On

Figure 1·12. Local Channel Attachment Data Flow

SY27-2512-3

1-9

SY27 -2512-3

1.3.9 Type A Adapter Coax Data Path

1.4 SUPPORTING PUBLICATIONS

Figure 1-13 illustrates the bit path from the coax to the

Additional information relating to ~he IBM 3274 Control
Unit, Models A, B, C, and D is presented in IBM 3270
Information Display System Library Users Guide,
GA23-0058.

Type A adapter.
Operator Panel
Indicators

Control
Logic and I-------i
Storage

Type A
Adapter

I/O Buffer
Adapter States

SERDES

1. Disabled
2. Enabled but Idle (Normal Polling)
3. Enabled Working (Passing Normal.
Data/Keystroke Activity)

Bit Parallel

Driver/Receiver

Bit Serial

Coax

~I
To Devices

Figure 1-13. Coax to Type A Adapter Data Flow

12-Bit Word Format

1123456 7 8 9 10 11112
Sync

Parity

1-10

Chapter 2. Subsystem Indicators, Symbols, and Messages

2.1 INTRODUCTION
This chapter provides information concerning the operator
panel indicators and the 3278 display symbols and messages
used to convey error and subsystem status conditions to the
user and to the customer engineer. The operator panel
indicators include the 8 4 2 1 indicators, the DC ON indicator, and the ONLINE/OFFLINE indicator (3274 Models
A, 8, and D only).
The subsystem symbols and messages displayed on the
3278 status line include the Readiness and System Connection symbols, Do Not Enter messages, Communication
Reminders, Shifts and Modes symbols, Printer Status messages, and Machine, Program, and Communication Check
numbers. The functional details of each item are described.

2.2 842 1 INDICATORS
The four indicators labeled 84 2 1 (Figure 2-1) are located
on the operator panel. They are activated by the control
logic to serve as prompting, progress, and/or success/failure
indicators during the following operations:
•

IML Bus Test: All four indicators are turned on by the
IML pushbutt?n via the control logic and the Type A
adapter card (01 A 1S2) if there is no activity on the
internal logic bus.

•

IML Tests: As the test routines are run, the control
logic turns on and turns off each of the four indicators.
A failure condition is indicated by a constant or flashing
code displayed in the 84 2 1 indicators. The success of
a given test is indicated by the 8 4 2 1 indicators progressing to the next hexadecimal value.

•

Operational Mode: During online operations with the
host CPU, the 84 2 1 indicators are turned on by the
control logic when an error condition is detected by the
control logic. Hexadecimal values are used to indicate
the most likely failing component. If additional errors
are detected the control logic writes over the prior indication with the new hexadecimal value. The indicators
turned on by the control logic may represent recoverable
errors or nonrecoverable errors. The error remains displayed in the 842 1 indicators until the machine is
powered off or until the IML pushbutton is pressed.

•

Customizing Mode: During customizing, the 842 1
indicators display the type of customizing operation in
progress, as well as serving as progress and proceduralfailure indicators. They also prompt the user to change
diskettes during customizing and notify the user when
customizing is completed.

Bus Test

Control
Logic

IML Pushbutton

.........--

• Installation Mode: During initial installation, the 842 1
indicators are used to indicate a successful test run after
initial machine power-on has occurred. They are also
used to show the state of the local channel interface
when attempting to run online tests (OL Ts) during initial
installation.
IML Tests
Operational Mode

2.3 DC ON INDICATOR

Customizing Mode

The DC ON indicator is located on the operator panel PC
board. It is turned on by +5 Vdc from fuse F1 (20A circuit)
on the LVPS PC board via the 21 cable to the operator
panel. Loss of +5 Vdc at the 01 A 1 logic board will turn qff
the indicator. This indicator is not related to the POR
circuit and does not indicate the status of +5 Vdc to the
33F D drive or the 01 A2 feature board.

SY27-2S12-3 :

Installation Mode

Figure 2-1. 8421 Indicator Control Logic

S2
Card

-8 On

"""--

-4 On

-2 On

r--- -1

SV27-2512-3
2.4 ONLINE/OFFLINE INDICATOR AND
SWITCH FOR MODELS A, B, AND D

Positioning the Power/Interface rotary switch to OFFLINE
causes the same operation; this time, however, toggling the
trigger
to the opposite state-turns on the OFFLINE
indicator and enables the IML pushbutton to function.

A description of the switch and indicator function for
Models A, B, and D follows. There are no rotary switches
on the Model C units.

Use one of the following procedures to force the 3274 offline:
1. If the 3274 will not go offline (the OFFLINE indicator
will not come on), request that the host CPU be stopped.
Power the 3274 off, and restart the host CPU.
2. Momentarily ground the pin:

2.4.1 Model A
Positioning the Power/Interface rotary switch to ONLINE
causes the following (Figure 2-2):

2.4.2 Models Band D

Use one of the following procedures to force the 3274
offline:

Positioning the Power/Interface rotary switch to ONLINE
causes the following (Figure 2-3):

1. If the 3274 will not go offline (the OFFLINE indicator

•. Switch Online and Microcrode Online condition AND
which is sampled by a sync pulse to set online
latch

fJ '

will not come on), request that the host CPU be stopped.
Power the 3274 off, and restart the host CPU.
2. Momentarily ground the pin:

• Setting the online latch turns off the OFFLINE indicator and deactivates the 1M L pushbutton.

Model B: A 1-02B07
Model D: A 1-02G05

Positioning the Power/Interface rotary switch to OFFLINE
deconditionsAND
causing latch
to be reset with
the next sample pulse. Resetting the online/offline latch
turns on the indicator and enables the IML pushbutton to
function. It should be pointed out that internal controllogic checks may also cause the 3274 Model B or D to go
offline .

Model A: Al-P2D10

• An exclusive OR function
gives output because the
trigger
and the Online/Offline switch do not agree.

2-2

• The output is interpreted as a request for change in the
state of the trigger

• A function is, in turn,sent and interpreted to toggle the
trigger

D .

OFFLINE Indicator

• Toggling the trigger
causes the OFFLINE indicator
to turn off and deactivates the 1M L pushbutton.

ONLINE/OFFLINE

Microcode
Online

IML Pushbutton

.....J
~>

r---

IML Load
S2M07

P2U10

Switch
Online

OFFLINE Indicator

P2U10

I
POR
P2D10

D
Interrupt to
Microcode

XOR
ONLINE/OFFLINE Switch
N2M13
P2J09

Toggle ONLINE/OFFLINE trigger

'0
0

e
(J

~
Logic Timing
Signal

-------4.------------f.__---l

When control logic detects
failure

------------------tI

IML Load

Notes:
1. If latch and switch do not agree, interrupt microcode.
2. Only accept toggle control code if latch and switch agree.
IML Pushbutton

Figure 2-2. ONLINE/OFFLINE Control Logic, Model A

Figure 2-3. ONLINE/OFFLINE Control Logic, Models Band D

S2M07

2.5 OPERATOR INFORMATION AREA
LAYOUT

2.5.1 Readiness and System Connection Symbols
The first six positions of the status line are allocated to
Subsystem Ready, Host Ready, Application Ready, and
Test. See Figure 2-5.

The operator information area consists of five key fields
located below the 3278/3279 status line. These five fields
are not displayed on any Category B device (3277). The
fields are (1) Readiness and System Connection, (2) Do Not
Enter, (3) Reminders, (4) Shifts and Modes, and (5) Printer
Status. The field lengths are shown in Figure 2-4.

Do Not Enter
(Input Inhibited)

Readiness and
System Connection
1

Symbol

Shifts and Modes

Reminders
17

Name

Explanation

3274 Ready

1 of the operator information areawhen the 3274 BI Control Unit to which
the display is attached is ready (functional) and the display is ready.

Online A
Online B

The Online A and Online B symbols govern transactions with the host system.
Certain keyboard functio~ and the n'leaning of some operator information
area symbols differ depending upon which set of rules is applicable.

Printer Status
41

Online A. The control unit is connected to the system under!!. rules. The A
symbol appears in remote systems using BSC protocol, in locally attached
systems that use 3274 Models Band D. It is turned on by receipt of the following commands: Write, Erase/Write, Erase All Unprotected, Copy, Read Modified, and Read Buffer.

Figure 2-4. Operator Information Area Layout

The

.a symbol is turned off when

1. An operator action causes host communication.
2. The display station is turned off.
3. The NormallTest switch is placed in Test, or the TEST key is pressed
to place the 3274 in Test mode.
Online B. The control unit is connected to the system under!! rules. The
B symbol appears in systems that use SNA protocol. It is turned on by
~mpletion of an ACTPU/ACTLU command sequence, and is turned off
by execution of DACTPU or DACTLU, including an internal DACTPU
sequence, and when the NormallTest switch is placed in Test or the TEST
key is pressed .

•

TEST

My Job

The display station is connected to the operator's application program. This
symbol is displayed in position 3. This symbol appears in systems that use
BSC or SNA protocol, or in systems that use 3274 Models Band D. In systems
using BSC or the 3274 Models Band 0, it is turned on with the A symbol, and
is turned off when power is removed, and when the Normal/Test switch is
placed in Test. When using SNA protocol, it is turned on when the operator's
application session owns the screen.

System Operator

This symbol is used with SNA protocol and indicates that the system operator
(SSCP Control Program) session owns the display screen. Except for the ENTER
key, the Program Attention keys are not functional when this symbol is
displayed.

Unowned

The display station is connected to the system (using SNA only), but not to the
operator's application program or to the system operator (control program).
The SYS REO key is used if LOGON is required. This symbol is displayed in
position 3.

Test

The display station is in Test mode. Test mode is initiated or terminated by
pressing the TEST key while holding the AL T key. TEST is displayed in
positions 3 through 6. Test procedures are described in the IBM 3270 Information Display System: 3278 Displav Station Problem Determination Guide,

GA27-2839.

Figure 2-5. Readiness and System Connection Symbols (Locations 1 through 6)

SY27-2512-3

2-3

2-4

SY27-2512-3
2.5.2 Do Not Enter (Input Inhibited) Symbols

All the Do Not Enter symbols are shown in Figure 2-6. All
the symbols contain an X in posi.tion 9 (do not enter),
combined with other symbols in positions 11 through 17,
which define why input is disabled. The keyboard does not
lock, but a change in state of the keyboard clicker (on-tooff or off-to-on) indicates that the keyboard is disabled.
The following symbols are arranged in descending order of
assigned priority. In case of multiple conditions, the higherpriority symbol is displayed.

The symbols shown in Figure 2-6 appear in positions 9
through 17 of the operator information area. Most of these
symbols indicate an operator error. However, there are
three categories of Do Not Enter symbols that are directly
related to hardware or program failur~s: machine checks
()( ~L program checks ()( PROG\), and communication
checks ()( ~~. Each of these symbols is accompanied
by a 3-digit code that further defines the erro r. The codes
are defined in paragraphs 2.5.6, 2.5.7, and 2.5.8.

Symbol

Name

Explanation

)(C>-.!

Secu rity Key

The security key is turned off, and no operator input can be accepted. When
the key is turned on, this symbol disappears, but any other preexisting "do
not enter" condition may then be displayed.

Machine Check

The display station is not working properly. The symbol is accompanied by
up to three digits, nnn (3278), which define the probable cause of the problem.
Recovery procedures depend upon the type of error.

nnn

Unavailable

)(

~nnn

)( PROGnnn

)( ::ba?

)(

)(
)(
)(

)(

*"+?
*'+?
*,..,+?
* .. +?

Communication Check

Program Check

)( +-*~

A message from the control operator was received and rejected. RESET should
be pressed to restore the keyboard. The operator may view the message by
pressing SYS REO or may defer viewing of the message until a later time.

)( SYSTEM

System Lock

The system has disabled the keyboard following an entry. The operator should
look for a message and then press RESET to restore the keyboard.
~

)( ?+

What (Try Again)

The last input was not accepted. The screen should be rechecked, and the operation should be retried as follows:
1. Do not key while the X is displayed.
2. If AL T, or a shift key, was used, press the key again; then press RESET and
retry the operation.
3. If AL T, or a shift key, was not used, press RESET and retry the operation.

Printer Not
Working

The printer assigned to the display station is not functioning. If this symbol
appears after the Print key has been pressed, the print request is canceled, and
the DEV CNCL key should be pressed to restore the keyboard. If the Printer
Failure symbol is displayed in the printer status areas, the printer stopped during
the last print operation. DEV CNCL should be pressed to restore the keyboard
and to instruct the control unit to stop monitoring the operations of the printer
that stopped.

Printer Busy

The printer assigned to the display station is busy. If the Printer Printing symbol
is displayed in the printer status area, the printer is printing. The operator may
wait for the printer operation to complete, or he may press the DEV CNCL key.
If the print key was used, it may be possible to select another printer.

Printer
Very Busy

This symbol means the same as Device Busy, except that more time than usual
is anticipated before the print request is accepted.

Time

Time is required for the system to perform a function.

Minus Symbol

The symbol you keyed is not available. The RESET key should be pressed to
restore the keyboard.

Minus Function

A currently unavailable function was requested. RESET should be pressed to
restore the keyboard.

Minus Function

Operator Unauthorized

More Than

An attempt was made to enter more information into a field than can be
entered. RESET should be pressed to restore the keyboard, and the operation
should be retried and the entry corrected.

A programming error was detected in the data received by the control unit.
RESET should be pressed, and the operation should be retried. This symbol is
accompanied by up to three digits which define the probable cause of the
problem.

Operator
Unauthorized

The operator has attempted to perform an unauthorized function. RESET
should be pressed to restore the keyboard. The printer status area (locations 60
through 64) should be checked for printer assignment. If the Operator Unauthorized symbol was displayed after the print key or I DENT key was pressed, a
printer is not assigned. (If the Printer Assignment symbol is displayed in the
printer status area, there is an error in the authorization matrix.) If the Operator
Unauthorized symbol was displayed after the I DENT key was pressed and two
numbers were entered, the operator is not authorized to use the printer.
These symbols indicate that an invalid dead key/character combination was
entered (Canadian French keyboard only). RESET should be pressed to restore
the keyboard, and a valid dead key/character combination should be entered.
Valid combinations are as follows:

,
I

aI A e

,..e ~

.. a ~
e E
1\

Go Elsewhere

Message
Received

A communication link error was detected and data cannot be sent. The RESET
key should be pressed. This symbol is accompanied by up to three digits, nnn
(3278), which define the probable cause of the problem. The communication
reminder symbol is displayed as long as the condition exists.

The wrong magnetic stripe card was used with the MSR. RESET should be
pressed, and the correct MSR card should be used.

*J+?

Explanation

The control unit is not equipped to handle a feature that has been invoked.
RESET should be pressed and another action initiated. (See Appendix B.)

Questionable
Card

Accent Plus
What

Name

Symbol

c ,c

E \u

{;-

E .. d

)( ((:.
)(

-s

)( -f

)(

-f

)(

***?

What Number

A numeral was entered that is unacceptable at the display screen location.
RESET should be pressed to r~store the keyboard, and the correct entry
should be made.

)(

*NUM

Numeric

A nonnumeric entry was made at a display screen location reserved for numeric
information. RESET should be pressed to restore the keyboard, and the
operation should be retried.

An action has been attempted that is invalid for the display screen location.
RESET should be pressed, and either the cursor should be moved or some other
action should be taken.

Figure 2-6. Do-Not-Enter Symbols (Locations 9 through 17)

)( c-c.::(.:.

2.5.3 Communication Reminder Symbol
The communication reminder (Figure 2-7) is turned on and
broadcast to all active Category A displays when the 3274
detects a failure in the local or remote communication path
to the host system. The reminder will remain on until the
failure condition has been cleared and the 3274 detects the
cleared condition. When the reminder is broadcast to all
displays, all retry activity has stopped. When a Bisynchronous line error has been detected, the original contents of
the screen are restored. The reminder then remains on the
screen of the display affected until cleared by host·system
recovery activity.

2.5.4 Sh ifts and Modes Symbols
There are three shifts and modes symbols (Figure 2·8). The
Upshift key may be used to determine if the Type A adapter
is still polling a display internally when the remainder ofthe
keyboard may be locked up. (The adapter is disabled if the
arrow ( i ) will not display.)

2.5.5 Printer Status Messages
Printer status (Figure 2-9) messages are displayed in the
operator information area layout whenever a printer has
been assigned to a display requiring the use of a printer.
Refer to the 3270 Information Display System: 3274 Control Unit Description and Programming Guide, GA23-0061
for detailed information regarding printer assignments,
classes, and matrix structures.

2.5.6 Machine Check Numbers

Symbol

Name

Explanation

~nnn

Communication
Reminder

The communication link connecting the control unit to the system is not
functioning. This symbol is displayed with the Communication Check
symbol.

Reserved

This symbol is reserved for future use and should be ignored if it is. displayed.

Figure 2-7. Reminders (Locations 21 through 27)
Symbol

Name

APl

APl mode

TEXT

Text mode

NUt1

Numeric

Explanation

The keyboard is in numeric shifts, which allows use of the 0 through 9 keys
and the U, H, and DUP keys only.

Upshift

The keyboard is in upshift.

Insert

The keyboard is in Insert mode. A character may be inserted at the cursor
location. Characters beyond the cursor position move to make room for the
inserted characters.

PSA
through PSF

Symbol set A through
Symbol set F

The EBCDIC code for characters entered at the keyboard will be used
to address the indicated symbol set for a displayable character.

Base Character Set

The base character set is addressed for a displayable character when the
operator presses a character key.

•

Extended Color

The color of the symbol is the color that will be used to display the next'
character at the keyboard.

Default Color

Green or white

Underlined

Character highlighting by underscore.

~,'a~

Blinking

Character highlighting by blinking on and off at regular intervals.

Reversed

Character highlighting by reversing the light intensity between the character
and its backgrou nd.

Operator Select

The current extended color attribute was selected by the operator.

Field Inherit

The current extended color is determined by the extended fieid attribute
(either (1 ) operator selection is allowed, but no selection has been made, or
(2) the operator has selected field inherit).

Figure 2-8. Shifts and Modes (Locations 37 through 41)

Symbol

Name

Explanation

o-c:::J--

Assign Printer

When changing the printer IDENT, the two numbers entered
appear in the printer authorization matrix.

Printer
Assignment

The display station is authorized to use printer number nn. Individual printers
may be assigned 01 through 31. Printer "class" is designated by 70 through 80.

~nn

Printer Printing

The printer identified by nn is printing.

~nn

Printer Failure

The printer identified by nn has stopped while printing.

o-c:::J??

What Printer

The printer IOENT has changed. Pressing the IDENT key causes displav of a
new printer assignment.

o-c:::Jnn

(Nothing
Displayed)

Machine check numbers follow immediately after the
machine check symbol (~). They are divided into the
following categories: Category A device and adapter errors,
Category B device and adapter errors, host attachment and
adapter errors, and control logic errors. The 200 series nnn
machine check numbers are used for the devices and their
respective adapter failures, and the 300 series nnn machine
check numbers are used for host and control logic failures.
For detailed descriptions, see Appendix B.

2.5.7 Program Check Numbers
Program check numbers follow immediately after the program check symbol (P R 0 G). Program checks are divided
into three categories: SNA protocol errors, print matrix
definition errors, and data stream errors. Some program
check numbers are not displayed at the device, but are
logged in the event log for that device. For detailed descriptions. see Appendix B.

2.5.8 Communication Check Numbers
Communication check numbers follow immediately after
the communication check symbol ( . ~ ). A communication check number may represent an interruption of the
communications path between a local channel attached
3274 or a remote teleprocessing attached 3274. The communication check number may also represent a normal
communication path condition and not a hardware failure
(for example, 532=BSC line idle). The communication
check numbers are directly related to the type of host
adapter being used. The meaning of the nnn number may
change from adapter to adapter. All communication check
nnn numbers are listed in Appendix B.

(X X)

If the display is attached to a 3274 (4 displayed in location 1), printing cannot
take place.

. Figure 2-9. Printer Status (Locations 60 through 64)

SY27-2512-3

2-5

Chapter 3. Subsystem Error Logs and Test Formats

3.1 INTRODUCTION

• Test 4 -

XX/4 There are six basic formats for entry into the subsystem log
and test facility. This concurrent test facnity provides path
tests between the control unit and attached devices, device
error statistics, device adapter error statistics, host adapter
error logs and statistics, control logic error statistics, configuration and EC data, display of the status of all configured devices, reset capability of statistical error counters,
and device control block displays for .all configured devices.
The use of the AL T and TEST keys is necessary to enter
Test mode. The concurrent test facility is available only
after Test mode is entered. Following are the concurrent
test and log facilities:
• Test 0 - Checks the communication path between the
3274 and its attached devices. Also provides
functional testing of Category A devices (displays 3278 and 3279) and four-color override
switch function on a 3279.

• Test 6 -

Reset logs.
Resets specified log counter (except summary).
Displays key information in device control
blocks.

00 to 31/6 -

For first (hex) 40 bytes. You may page
from one page to the next by pressing the
ENTER key. Paging beyond display DC
will result in a locked keyboard and X-f
displayed on the status line. For extended
DCB, paging is extended for displays 10,
14, 18, and lC.

• Test 7

Color Convergence.

• Test 8

Programmed Symbols, Highlighting, and Color
Test.

3.2.1 Description

00 to 31/0 - Transmits a test pattern from the control
.unit to another Category A display as
specified by you when you entered the
Test 0 format message.

• Transmits a test pattern from the control unit to the
display from which you requested Test O.

• Test 1 -

Displays error statistics for displays, printers,
adapters, and control logic.

00 to 31/1 AO/1 -

A 1/1 -

Test 0 performs the following functions:

• Test 2 /2 -

Displays the host adapter/attachment log
formats: CCA BSC, CCA SDLC, HPCA, LCA
attachment, and LHA or SLHA attachment.
Only the format for the host adapter installed
in your machine is displayed in response to this
request.

•

Functionally tests the following using the test pattern
transmitted by the control unit to the Category A display specified by you: (1) high-intensity function
(3278 only), (2) nondisplay function, (3) various key
functions, (4) selector-pen function, (5) MSR function,
and (6) audible-alarm function.

•

Displays log of the Type A adapters.

Displays configuration information.

(Enter key only) - For second 40 bytes ..
Displays the status (off, on, disabled) of all
configured devices and summary errors~

/3 - Status of ports and summary error counters.

If no device is specified when the test is requested, an automatic default to the requesting device occurs.

Executes communication path test tu Category B
display (3277).

•

Four-color function and override switch (3279 only).

Ensure the cursor is at location zero (0). Enter the
following: (1) the device number you wish to test, using
any 2-digit number from 00 to 31, (2) a slash, and (3) a
zero. Press the ENTER key.

•

If you are testing a Category A display, the following
pattern will appear on the screen if the test is successful:
TEST: 3274;NN
?SEL PEN
SEL PEN
&SEL PEN > SEL PEN
DISPLAY INSERT CK
NN

= The port number of the terminal that requested
the test

If the device has the Wait indicator on and is attached to
a Model B or is busy executing a command that requires·
asynchronous ending status (Op Complete), Do Not
Enter minus function indication is returned.

00 to 31/1 - Displays log of any device from 00 to 31.

• AO/l -

• Al/1
• A2/1
•

Displays the host adapter/attachment log formats: CCA BSC, CCA SD LC, HPCA, LCA
attachment, and SLHA and LHA attachment.
Only the format for the host adapter installed
in your machine is displayed in response to this
request.
Displays log of the Type A adapters.
Displays log of the Type B and Encrypt/Decrypt
adapters.

A3/1 - Displays control logic error log.

The error information contained in the above logs resides in
the 3274 storage. The general format of all logs reflects
(1) the most recent error event information and (2) statistical counters that reflect the type of errors occurring. The
event log may be a combination of significant information
that will differ in content from adapter to adapter as well as
in format. The statistical counters record errors using hexadecimal v~lues. The maximum value for any counter is
hex 'ff'.
The terms used in the log descriptions are defined as
follows:
Machine Check - The CCA hardware has detected an error,
and the failing operation is retried. If the retry is successful, the error is transparent. If the retry fails, the CCA is
disabled and the machine check is logged. See nnn code
310 in Appendix B.

For a color description, see the 3274 Problem Determination Guide, GA27-2850, for device specific character'
istics of this test.

Invalid Status - The control logic has detected an unexpected or invalid combination of bit settings in the CCA
Status Register. See nnn code 311 in Appendix B.

•

Use the IBM 3278 Display Station Maintenance Information manual (SY27-2510) and 3274 Control Unit Maintenance Information manual (SY27-2530) to run the
3278 functional tests with the above test pattern.

DCE, - The contr-ol logic has detected the loss of Data Set
Ready (DSR) from the modem. See nnn code 501 in
Appendix B.

•

• If the device requested is in an SNA session, the test
pattern function is not performed. Do Not Enter minus
function indication is returned.

•

• To exit Test mode, press and hold AL T and then press
TEST.

A request for Test 0 will be executed to any Category A
display except under the following conditions:

•

Press and hold ALT; then press TEST to enter Test
mode.

•

• Executes communication path test to Category A or B
printers.

Displays log of the configured terminal and
summary counters.

For first (hex) 40 bytes.

• Test 3 -

Transmits a test pattern from the control unit to another
Category A display as specified by you when you entered
the Test 0 format message.

Displays log of any device from 00 to 31.

A2/1 - Displays log of the Type B adapters, Encrypt/
Decrypt adapter.
A3/1 -

•

device log or adapter log information can be retrieved. The
formats for entering a Test 1 request are as follows:

• The test message you entered followed by a: +, -, or O.
+ = Test successful or path OK.
- = Test failed, device disabled because of error
0= Test not run, device powered off

3.2.2 Procedure for Requesting Test 0

3.2 TEST 0: COMMUNICATION PATH TEST
AND 3278 DISPLAY TEST

/0 - Transmits a test pattern from the control unit to
the display from which you requested Test O.

This test, if requested for a Category B display (3277) or
Type A or B printer, only checks the continuity of the coax
communication path. Success or failure of this test is displayed on the requesting Category A display as follows:

An entry of slash (/) only automatically defaults to
Test 0 on the requesting display.

3.3 TEST 1: OV ERVI EW
Test 1 is a variety of device and adapter error log and statistical counter information that can be displayed on any
working 3278/3279 while that 3278/3279 is in Test mode.
By using a 2-digit prefix to the entry slash (/) 1, specific

SY27 -2512-3

Timeout
Read Operation - This bit indicates that 3 seconds has
elapsed without receipt of an Syn, ETX, or ETB.

Write Operation - See nnn code 530 in Appendix B.
Overrun
CCA - The 3274 was not ready to receive a byte of data
from the device.

HPCA - Either the cycle-share buffers were full or the
3274 did not allow the adapter to cycle-share.
Underrun - The 3274 was not ready to transmit a byte of
data at the time the transmission line was ready to receive it.

3-1

SY27 -2512-3

NA K Received - A Negative Acknowledgment has been
received.

are displayed.) Since four types of device logs are available
when using Test 1, it is necessary to determine what type of
device (3278, 3277, Category A printer, Category B printer)
is attached to the device port nu mber (00-31) for wh ich you
are requesting log information. The format for all device
logs requested using Test 1 is as follows:

15 NAKs Received - 15 Negative Acknowledgments have
been received.

•

Enq Received - An enquiry character has been received by
the 3274.
NAK Sent - A Negative Acknowledgment has been sent.

15 NAKs Ack - 15 Negative Acknowledgments have been
sent.
N Timeouts Invalid - N = number of invalid timeouts that
have occurred.
15 Timeouts Invalid - 15 invalid timeouts have occurred.

•

Count Exceeded - The byte count has been exceeded.

RVI RCVD - A reverse interrupt was received instead of
ACK alACK 1.

This line is returned exactly as you entered your request.
Example: You entered 01/1, and the fi rst Iine of the
display sent back to you should be 01/1.

Following is a device log as it would appear for an intermittently failing 3278 display on control unit port A 17.

If error information had been recorded, the second line
of this display could appear as follows:
0400 0032

Poll/Select - This bit, when 1, indicates that this station
has been polled. When this bit is 0, this station has to be
selected.

04 = The most current 200 series error, in this example,
204, which is a device check.*
00 = No 300 series errors are recorded.
00 = No 400 series errors are recorded.
32· = The most current 500 series error, in this example,
532, which is SSC line idle.

3.3.1 Test 1 Device Logs
Perform the following steps before consulting the log:
1.

If any 84 2 1 indicators are set, refer to the MIM for
the failing FRU.

If a 3nn or 5nn code is displayed, refer to Appendix B for problem determination information.
These codes can be found in the device logs.

If the above steps do not provide sufficient information for
problem determination, then the log may be of assistance.
The log statistical counters indicate the state of the interface (how many errors of a certai n classification), and the
event data provides error status on the interface for certain
error events. For example, in SSC operation when an NAK
is received (associated with a severe error condition), it is
logged with associated event data and counted. This event
data should be the last error information examined. The
control logic normally examines the appropriate error data
and sets the nnn code to the appropriate value.
The device logs should be accessed whenever a specific
device is suspected of experiencing intermittent or difficultto-define errors. These errors mayor may not be generating
nnn numbers on the failing device. (Not all nnn numbers

17/1
1200 0000
0000 001C 0000

Line 20000 0000

0000 0000

XPRNCY - The receive operation has entered the transparent mode.

*All counters increment to FF and remain at FF until
reset.

01/1

ITB ATTN - An ITB character was received.
EOH ATTN - An STX character was received signifying
the End of Header.

Counter number 03 = 1 A hex = 26 power-off total
Counter number 04 = 00 hex = no errors
Counter number 05 = 00 hex = no errors
Counter number 06 = 13 hex = 19 errors total

All counters for line3 function in this manner. The
counter numbers are assigned specific meanings according
to the type of device log being requested. (See Figure 3-1.)

Line 1 -

This line displays the most current low-order digits of
200, 300,400, and 500 series nnn numbers. If there are
no errors generating nnn numbers, the second line of this
display will appear as follows:

RI - Ring Indicator (not used)

3-2

The 200 numbers appear in the leftmost position and
progress to the 500 numbers in the rightmost position.

Line 30000 0000 0000
This line displays the statistical counter information associated with this device. If no errors are recorded for this
device, the counters will display as follows:

Type A Printer Log

3278/3279 Log Detail (continued)

Counter Meaning

Counter

01
02
03
04
05
06

Coax timeouts
Coax parity errors
Power off
Device checks
Error status base
machine
Error status
features

Counter Meaning

Coax timeouts
Coax parity errors
Power off
Device checks
Error status

Equipment checks

Coax timeouts
Coax parity errors
Power off
Device checks
Not applicable
Not applicable

05
Type B Printer Log

3277 Log

01
02
03
04
05

Counter Meaning
01
02
03
04
05
06

Coax timeouts
Coax parity errors
Power off
Device checks
Sync or equipment checks
Disabled or equipment checks

3278/3279 Log Detail

Coax timeouts - This counter is incremented when the
3274 sends data or commands to the device and does not
receive a response in a predetermined period of time.
Note: Use the nnn code logged for the device for further
analysis.

Coax parity error - This counter is incremented when the
3274 detects a parity error in a 12-bit byte received from
the device.
Normal power off - This counter indicates the number of
times the device failed to respond to a poll retry sequence
jdevice powered off). Counter 1 or 2 is incremented on
the first failure to receive a poll sequence response; 32

Figure 3-1. Summary of Counter Definitions by Device Log Type

Meaning
successive poll sequence retries by the DCA then follow.
If all retries are unsuccessful, the control logic assumes
that the device is powered off and then increments
counter 3.
Device checks - The device has detected an error and has
returned device check status to the 3274. See nnn code
204.
Error status base machine - Error status has been
returned that indicates a device failure.
Error status features - An invalid response or error
response has been received .from a featu re device.

Type A Printer Detail
Counter Meaning
01
02
03
04
05

Counter Meaning

02FF lAOO 0013 0000
Counter number 01 = 02 hex = 02 errors total
Counter number 02 = F F hex = 255 errors (maximum)*

The host adapter logs should be accessed whenever a problem is suspected to be intermittently causing host communication failures, host adapter failures, or other spurious or
difficult-to-define failures. When a host adapter log is
requested, the format will always be AO/1. The display
sent from the Gontrol unit in response to this request will

Counter Meaning

0000 0000 0000
The counters are not numbered when they are displayed.
They are, however, assigned counter position numbers.
The leftmost 2-digit position is counter number 01, and
the rightmost counter position used is counter number
06. The value in eachcounter is given in hexadecimal.
If errors were being recorded for this device, the display
for line 3 would appear as follows:

3.3.2 Test 1 Host Adapter Logs

3278/3279 Log

*A 2%% nn code wi II appear as E E in the error log.
•

If the log for this device is broken down, there is a record in
the nnn number field showing that a 212 (invalid scan code
received) error is the most recent 200 series error and that
no other nnn errors are recorded. Counter number 04 has
a value of 1C recorded, indicating that 28 device checks
were pointing to this display as the source of failure.
Repair activity can now be attempted at the display level.
Control-unit failure is not suspected.

Coax timeouts - See 3278/3279 log detail.
Coax parity error - See 3278/3279 log detail.
Normal power off - See 3278/3279 log detail.
Device checks - See 3278/3279 log detail.
Error status - An error condition has been detected .
by the 3274, or error status has been received indicating
a device failure.
Equipment check - The printer has reported an unrecoverable error to the 3274;

Type B Device Log
Counter Meaning
01
02
03
04
05

Coax timeouts - See 3278/3279 log detail.
Coax parity error - See 3278/3279 log detail.
Normal power off-See 3278/3279 log detail.
Device checks - See 3278/3279 log detail.
Sync or equipment check - The printer has returned
sense information that indicates an equipment check
while printing. See nnn code 276 in Appendix B.
Disabled and equipment check - The printer has posted
an equipment check and is in a not-ready condition. See
nnn code 275 in Appendix B.

depend on the type of host adapter installed in your 3274.
The display for each host adapter is slightly different. The
display returned in response to an AO/1 request is covered
in detail in subsequent sections; in general, however, all displays appear as follows:

•

XXXX. Not used.
•

Line 1 - AO/1

•

Line 2 - Event data is displayed

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

•

Line 3 - This line displays the statistical counters associated with each host adapter

The counters are not numbered when they are displayed.
They are, however, assigned counter position numbers. The
leftmost 2-digit position is counter number 01, and the
rightmost counter position used is counter number 10. The
remaining positions are not used. The value in each counter
is given in hexadecimal. The maximum value for any counterisFF.

The host adapter logs can provide detailed information
pertaining to the following questions: (1) What was the nnn
number at the time of the last failure? (2) What was the
operation being attempted .at the time of the last failure?
(3) How was that operation completed? (4) Why was that
operation completed that way? (5) What is the frequency
of this type of failure? If these questions are answered
with the use of the information stored in the host adapter
logs, remedial or repair activity can be attempted.

3.3.3 Test 1 Common Communications Adapter
(CCA) Log for BSC
This host attachment log format is returned to the requesting 3278 in response to an AO/1 entry. The format detail
is as follows:
•

Line 1 - Returned the same as input, AO/1.

Line 2 - Twenty-four bytes are displayed ~n this line,
but only 10 are used. The individual bytes are
not labeled when displayed. Each byte is
assigned a specific meaning. See the following
example for byte identification:
Byte 1
Byte 24
0000
0000
0000
0000
0000
0000 .»
0000
NNFF ccce SSSS
XXXX «(
SSSS
SSSS
•

xxxx

NN. This code represents the two low-order digits of
any 500 series nnn number in almost all cases. However,
if NN equals zero (00) and the bytes labeled FF and ecce
are not zeros, then the entire log information does not
pertain to a 500 series communication check and is to be
considered machine-check data.
FF. This byte represents the type of operation being
attempted at the time of the failure. See Figure 3-2 when
FF is to be used.

cccc.

These two bytes indicate how the attempted
operation ended. See Figure 3-3 to determine whether
the operation was completed (1) normally, (2) with
exception, or (3) with error.
SSSS. These five bytes contain sense information recorded
at the time of the failure. After you have examined NN,
FF, and CCCC, the SSSS bytes should give you some indication as to why the nnn code was generated and why the
operation attempted was not completed normally.

Line 3 - This line displays the statistical counter information associated with this adapter. If no
errors are recorded for this adapter, the counters display as follows:

•

Recovery Process

If the error occurs elsewhere in the transmission, the
transmission will stop and the control unit will wait
3 seconds and then send an ENO. If the host sends
the previous AGK, the entire message will be
transmitted.

Counter

Meaning

nnn Code*

Code

Operation
Attempted

01
02
03
04

NAK sent
NAK received (see below)
ENO received (see below)
Timeout invalid
(15 ENOs sent)
15 NAKs received
15 Wrong ACKs (ACK a
instead of ACK 1, etc.)
Unde rru ns/overru ns
(see below)
Write timeout
DCE error
Number of Available Buffers
Exceeded (see below)

531

Enable/Set Mode

Sense Hardware

SOH/ETX
Conversational
Response

07
08
09
10

533
534
535
536

530
501

Read Normal

*See Appendix B.
The following descriptions of conditions will help you analyze the logs:
02 NAK Received - When an NAK is received in response
to a block of transmitted text, the counter is incremented.
The adapter attempts to recover by retransmitting the
block of text (see counter 05 and nnn code 535).
03 ENQ Received - The counter is incremented if an ENO
is received within the text stream or when associated with
a 3-second timeout. See NAK sent.
07 Underrun/Overrun
These conditions are detected by the GGA hardware and
are described as follows:
•

Underrun - Underrun occurs when the GGA is being
clocked to put another byte (to be sent) on the communication line when the byte has not been provided by
the control unit.

• Overrun - This condition occurs when the GGA has
received a byte of data but cannot place it in the input
register because the control unit has not processed the
previous byte received (input register is full).

A complete log display for this adapter would appear as
follows:
AO/l

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

If the error occurs on a receive operation, the remaining incoming data will be ignored and the control
unit will wait for the host to send an ENO. When
the ENO is received, the previous ACK will be
returned and the host will retransmit the block of
text.

Each counter is assigned a specific meaning, as follows:

05
06

10 Number of Available Buffers Exceeded - This condition
is not considered a communication check. It results from a
data stream that the 3274 cannot handle. A sense/status of
the operation check and EOT will be sent to the host.

If the error occurs at the beginning of the transmission (during PADs or SYNs), the transmission will be
restarted.

Read-Respond RVI

SOH/ETB
Conversational
Response

SOH/ETB
Nonconversational

Write EOT

STX/ETX
Conversational
Response

FF
Description

Code

Operation
Attempted

Initializes the CCA for the customizing options specified. When
the adapter is enabled, it will
assume a Receive Monitor mode.
Provides current status of the
hardware portions of the adapter.
Used to respond to a received
Text/Header format with a Text/
Header format transmission in
place of a positive acknowledgment; for example, on a Read
Modified command from the
host.
Causes the adapter to transmit
the appropriate acknowledgment
(ACK 011) and turns the line
around to receive.

Write WACK

STX/ETB
Conversational
Response

STX/ETB
Nonconversational Mode

Monitor Line

Mon itor-Response
EOT

SOH/ETX Expect
Conversational
Response

STX/ETX Expect
Conversational
Response

Monitor LineRespond WACK

Transmits an RVI in place of the
ACK 0/1 and turns the line
around to read.
Used to respond to a received
Text/Header format with a Text/
Header format transmission in
place of a positive acknowledgment (error occurred during the
processing of a Read Modified
command).
Transmits a Text/Header format
to the host in response to a poll
(Test Request message).
Initiates an EOT control
sequence.
Used to respond to a received
Text/Header format with a Text/
Header format transmission in
place of a positive acknowledgment; for example, when a Read
Modified command is received
from the host.

Description
Initiates a WACK control
sequence; for example, during a
print operation.
Used to respond to a Receive
Text/Header format with a Text/
Header format transmission in
place of a positive acknowledgment; for example, on a Read
Modified command sent from
the host.
Transmits a Text/Header format
to the host in response to a poll;
for example, an Enter Key
operation.
The adapter will monitor for
receipt of its station address in a
polling or selection sequence.
Initiates an EOT control sequence
and then a return to Monitor
mode; for example, when no
action is required on a poll
sequence.
Permits a conversational response
to be received in response to a
transmitted Text/Header format;
for example, on a Status (DE) to
the host.
Permits a conversational response
to be received in response to a
transmitted Text/Header format;
for example, on an Enter Key
operation.
Initiates a WACK control
sequence and then a return to
Monitor mode; for example,
when the device is busy or when
a selection sequence is in process.

Figure 3-2. CCA BSC Operation Attempted Chart (Code FF)

SY27 -2512-3

3·3

3-4

SY27 -2512-3
Operation Attempted

Operation Attempted

Left CC Byte
(Completion)

00 Enable/Set Mode
Left CC Byte
(COri1pletion)
Bit

Right CC Byte
(Detail)

4' 5

1 0 0

Normal Completion
RVI

0 0

Error Completion
Halted
Overrun/Underrun
. Invalid Basic Status
DCE
Machine Check

Exception Completion
Timeout

Bit

2 3 4 5 6 7

0
0

0 0

II
0

00 0

1 0

Bit

1 0

Bit

2 3 4 5 6

0
0

OE SOH/ETB Nonconversational
0

01 Hardware Sense
Normal Completion
0 0
(No error or exception condidon allowed)

2 3 4 5 6

OA SOH/ETB Conversational Response

I
0

Exception Completion 2
N Timeouts Invalid
ITB Attention
EOH Attention
Transparency
NAK Sent
TID Received
15 ENOs Received,

Right CC Byte
(Detail)

02 SOH/ETX Conversational Response
03 Read Normal

10 Write EOT
Normal Completion

Error Completion
Underrun
Invalid Basic Status
DCE
Machine Check
Timeout

1 0

(Exception completion not valid for Write EOT)

06 SOH/ETX Nonconversational
12 STX/ETX Conversational Response
07 Read and Respond .RVI
14 Disable
Normal Completion
STX=O
SOH=l
ETX=O
ETB=1

Error Completion
Write-O
Read=l
Halted
Underrun/Overrun
Invalid Basic Status
DCE
Machine Check
Timeout

Exception Completion 1
EOT Received
Count Exceeded
Disc

0 0 0

1 0

1 0 0

1 0

I II

Normal Completion

0 0

Error Completion
Invalid Basic Status
DCE
Machine Check

0 0

0 0
0 0

(Exception completion not valid for Disable)
16 STX/ETX Nonconversational
18 Write WACK

1 0

Note: Bits shown as 0 are not used unless specified otherwise.

Figure 3-3 (Part 1 of 2). CCA BSC Operation Ending Chart (Code CCCC)

Normal Completion

Error Completion
Write=O
Read=1
Halted
Underrun/Overrun
Invalid Basic Status
DCE
Machine Check
Timeout

0
0

Operation Attempted

Operation Attempted
Left CC Byte
(Completion)
Bit

Right CC Byte
(Detail)

23456

Bit

Left CC Byte
(Completion)

2 3

456

000

Exception Completion
o 0 0 0
o 0
o o
EOT Received _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _..J

Bit

Disc -----------------------------------------------~

Bit

Exception Completion 2
o 000 0 0
o
o 0 0 0 0
WACK Received
NAK Received ___- - - - - - - - - - - - - - - -_____________--..J

0 0 0

1 0

15
'111
ITB Timeouts
AttentionInvalid-'_ - - - , - - - - - - - - - J
EOH Attention _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _---J
Transparency ________________________________---J

1E STX/ETB Nonconversational
40 Monitor Line

NAK Sent
TTD Received _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _----J

Normal Completion
Pol/=1
Select=O

Error Completion

0 0 '1

0 0

000 0

000

15 ENOs Received - - - - -____________________________________---l
58 Monitor Line Respond WACK

0 0

1 0 0

III
1

Halted -----------------------------------~
Overrun
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _-J

~~~id Basic S t a t u s - - - - - - - - J

Machine Check
.
Timeouts-------------------------------------J

46 SOH/ETX Expect Conversational Response
56 STX/ETX Expect Conversational Response

FF Codes 44 through 58 use the following completion detail.
Normal Completion
PolI=1
Select=O

1 0

T i m e o u t - - - - - - - - - - - - - - - - - - - - - - - - - - - -_ _ _ _ _ _~
Exception Completion
00000010
o
One Tjmeout Invalid _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _----.J

ETB=1
1

000

DCE----------------------------------------------------__----J
Machine Check - -_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _....J

00000

SOH=1
ETX=O ________________________________________________

000

I II

Underrun/Overrun'
Invalid Basic Status - - - - -________________________-1.

o
o 0 001 000
Normal Completion
STX=O ______________________________________________

0 0

00001000

Error Completion
00001 100
Read=1 ________________________________________--..J
Write=O
Halted - - - -_________________________________________--l

FF codes 02 through 56 listed above use the fol/owing completion/detail.

Error Completion

234567

23456

Exception Completion 3

1A STX/ETB Conversational Response

Right CC Byte
(Detail)

1 0 0

I II

---------------------------------~

1 1

0 000

Note: Bits shown as 0 are not used unless specified otherwise.

Write=O
Read=1
Halted -----~------------------------'
Underrun/Overrun - - - - - - - - - '
Invalid Basic Status _ _ _ _ _ _ _ _'--_ _ _ _ _ _ _ _ _ _ _ _ _ _ _..J.

DCE
Machine Check - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - '
Timeout -------------------_-------------~
Invalid Data

-----------------------------------1

Exception Completion 1

1 0

-......-----~

15
Timeouts
11.1
EOT
ReceivedInvalid
--------------------------------'
RV I Received - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - '
Count Exceeded ___________________________________---'
15 NAKs Received
15WrongACKs~.---------------------------------~

Disc

Figure 3·3 (Part 2 of 2). CCA SSC Operation Ending Chart (Code CCCC)

SY27 -2512-3

3-5

SY27-2S12-3

3-6

Figure 3-4 explains the sense-byte breakdown for CCA
BSC. These conditions are logged only for nnn codes 311,
501,530, 535, and 536, and the last error condition of
that type.

3.3.4 Test 1 Common Communications Adapter
(CCA) Log and High-Performance
Communications Adapter (HPCA) Log for
SDLC

CCCC - These two bytes indicate how the attempted operation ended. See Figure 3-6 to determine whether
the operation was completed (1) normally, (2) with
error, or (3) with exception.

Line 2 - NNFF CCCC SSSS SSSS SSSS
010203040506

This host adapter log format is identical for both adapters
and is returned to the requesting 3278 in response to an
AO/1 entry. The format detail is as follows:

SSSS -

SS bytes are labeled from left to right SS01, SS02. SS03, etc.
Location
Byte SS01
Byte SS02

2
3
4
5
6
7

Byte SS03

0
2
3
4
5
6
7

Byte SS04

Ignore
Input Request
Output Request
DCE Interrupt
Timer Interrupt
Exception
Machine Check/Prog Check
Enable/Disable
Interrupt Request
Data Set Ready
Clear to Send
Recv Line Signal Det
Ring Ind
DSR Transition
Reserved
R LSD Transition
CTS Transition

0
2
3
4
5
6
7

Byte SS05

Line 1 - Returned the same as input, AO/1.

•

Line 2 - Twenty-four bytes are displayed on this line,
but only 11 are used. Information is stored
and displayed only in line 2 for specific error
conditions. These conditions are associated
with nnn codes 501,502,529,530, and 321
(see Appendix B for details). Code 321 will
be indicated in this line as NN=OO, and the
remainder of line 2 will be not equal to O.
Each byte is assigned a specific meaning. See
the following example for byte identification:

Meaning If Bit Is Turned On (1)

Bit
0

•

0
1
2
3
4
5
6
7

DTR/CDSTL
Request to Send
Wrap
Test
Select Standby
Select Half-Speed
New Sync
DCE Interrupt Disable
Overrun
Underrun
Receive Clk Runningl
SDLC Invalid Seq
SDLC Frame
Invalid Character!
Break Byte Detected l
Adapter in Sync

NN -

This code represents the two low-order digits of any
500 series nnn number in almost all cases.

FF -

This byte represents the type of operation being
attempted at the time of the failure. See Figure 3-5
when F F is to be used.

Code

Operation
Attempted

Open

Byte SS06

0
1
2
3
4
5

6
7
1

Receive Mode
Transmit Mode
Inhibit Zero Insertion
Mode Select 2
Mode Select 2
+ Code Length
+ Code Length
NRZI

Sense

Write

Description
Initializes the communication
adapter and associated control
blocks.
Issued by the control logic to the
communication adapter to determine the current status of the
adapter hardware.
Transmit or receive data to/from
the primary station. A read is
implied (any FF code) and is indicated by an exception completion
with Read Message AVailable
(bit 6 of the right CC byte) set.
Terminates communications on
the SDLC line and disables the
communication adapter from
generating interrupts.

Should always be zero

200 = Auto
+00 = 8
01 = EBCDIC 01 = 6
10 == ASCII
10 = 7
11 =SDLC
11 = 5

•

Line 3 - This line displays the statistical counter information associated with these adapters. If no
errors are recorded for these adapters, the
counters will display as follows:

Byte 24

0000 0000 0000 0000 0000 0000 0000 ) 0000
NNFF CCCC SSSS SSSS SSSS SSSS XXXX( (XXXX

XXX X - All bytes labeled XXXX are not used in the CCA
and should be ignored for the HPCA, since these
bytes contain secondary levels of information
not associated with the problem.

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

Byte 1

These six CCA and 17 HPCA bytes contain sense
information recorded at the time of the failure.
After NN, FF, and CCCC are examined, the SSSS
bytes should give some indication as to why the
nnn code was generated and why the operation
attempted was not completed normally.

The counters are not numbered when they are displayed.
They are, however, assigned counter position numbers.
The leftmost 2-digit position is counter number 01, and
the rightmost counter position used is counter number 12.
The remaining positions are not used. The value in each
counter is given in hexadecimal. The maximum value for
any counter is F F .
Each counter is assigned a specific meaning, as follows:
Counter

Meaning

nnn Code*

01
02
03
04
05
06
07
08
09
10
11
12
13

Nonproductive Timeout
Idle Timeout
Write Retry
Overrun
Underrun
Connection Problem
FCS Error
Primary Abort
Command Reject
DCE Error
Write Timeout
Count Exceeded
Secondary Busy

520
521

The error-to-nnn-code-and-counter relationship is shown
below:
Error

nnn Code*

Counter

DCE Error
Machine Check
CCA
HPCA
Invalid Status
CCA
HPCA
Write Ti meout
Nonproductive Timeout
Idle Timeout
Overrun
Underrun
Connect Problem
Secondary Busy
Write Retry
FCS Error
Pri ma ry Abort
Command Reject
Lost Data

529

Figure 3-5. CCA/HPCA SOLC Operation Attempted Chart
(Code FF)

321
331
530
521

525

528
519

11
01
02
04
04
06
13
03
07
08
09
11

*See Appendix B for a description of the nnn codes listed.
The following descriptions of conditions will help you
analyze the logs:
•

Read Message Available - Indicates than an I-frame has

been received and is destined to a physical or logical unit.
•

Link Test - Used in conjunction with the Read Message
Available bit. When both bits are on (1), it indicates
that the I-frame received is a test message.

• Poll Request - This bit indicates that a valid poll has

been received from the host.
• SNRM Received - A Set Normal Response Mode

sequence has been received from the host. An existing
session will be terminated and a new session may be
established.

525
•

528
529
530
519

Underrun - The 3274 Control Unit was not ready to

transmit a byte of data at the time the transmission was
ready to receive.
•

Connection Problem - 20 consecutive occurrences of

any of the following: ROL, FRMR, XIO, NSA.
•

FCS Error - The 3274 Control Unit detected an SOLC

frame with an invalid block check character (BeC) or a
frame-check sequence.

*See Appendix B for a description of the nnn codes listed.
•

bit
bit
bit
bit

320
330

Primary Abort - The 3274 detected an abort message

from the primary station.
•

Lost Data - An I-frame received by the 3274 was larger
than the allocated buffer.

• Write Timeout - A transmission of data took longer
Figure '3-4. Sense Byte Breakdown Chart for CCA BSC
(Code SSSS)

than expected and is suspected to be a result of a hardware function.

Dump Message - Addition status is contained in the register space that will indicate one of the following:
Operation Attempted

•

FCS Error

•

Primary Abort

•

N (r) Sequence Error

• Wrong Length Message (same as lost data)
•

Data with a command

•

Invalid SDLC command

. Secondary Busy - An RNR response has been sent to the
primary station because the 3274 does not have sufficient
buffers (receive).

Nonproductive Timeout - No valid SDLC frame has been
received by the 3274 that contains either a valid FCS or a
valid address for a period of 20 seconds.

XID Received - A valid XID was received from the primary
station. The 3274 will go to normal disconnect mode
(N D M) of operati on.

Left CC Byte
(Completion)
Bit

Right CC Byte
(Detail)
4

Bit

Machine Check - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - '

Exception Completion 2
(Open Halted)

0000101

•

HPCA - Either the cycle share buffers were full or the
3274 did not allow the adapter to cycle-share.

A complete log display for this adapter would appear as
shown below:

23456 7

Write Complete and Read Intermediate
o 0 0 0
0
0
LostData----------------------------______________________~
Read MSG Available - - - - - - - - -__________________________- - '
Exception Completion 4
(Halted Write Only)

0·1

000 0

a a a

000 0

Read/Write

0 0

000

a a

o a

DCE Error
Machine Check - - - - - - - - -_______________________________--'
(Exception completion condition not allowed)

000 0

000

000 0 000 0

DCEError
--------------------------------------------~
Write
Timeout
_________________________________________--1

05 Adapter Prewrap
09 Adapter Wrap

00 Modem Wrap

Machine Check ---------------------------~
Read Intermediate Complete

FF Codes 05 through 00 are not logged.

-----3

0 0

1 1

XID
Li n k Received
Test -----------------------------------------Nonproductive Timeout (Receive Overrun for HPCA)

Notes:
1. Bits shown as 0 are not used unless specified otherwise.
2. Bits 0-3 of left CC are ignored.

Poll Received - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -___________________--'

• CCA - The 3274 was not ready to receive a byte of
data from the device.

Bit

Error Completion
0
I nvalid Basic Status ___________________________________---'

Ring Indicate - A switched connection has been made.

Overrun

2 3 4 567

0 0

been detected in a 3-second period.

DeE Error - A modem problem has been detected.

Right CC Byte
(Detail)

04 Close

Lost Data - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Secondary Busy ---------------------------------------------------.....
Read MSG Available __________________________________________

Invalid Basic Status - An adapter hardware register contained data that was not meaningful.

Bit

Normal Completion
ExcePtion Completion 1
00000010
000
Ring-Indicate Timeout - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -_______--1

Error Completion
0 0 0
0
Invalid Basic Status __________________________......J

Ring Indicate Timeout - A switched connection has not

Normal Completion
000 0
000
000
Ring Indicate
Error Completion
000 0
o 0
o
Invalid Status
DCEError--------------------------------------------______~

Disconnect command was received from the primary station. The 3274 will go to normal disconnect mode (NOM)
of operation.

Idle Line Timeout - No valid flag characters have been
detected on the host link for 20 seconds.

Left CC Byte
(Completion)

a a

Write Complete

received by the host. The 3274 will transmit the same
I-frame again.

00 Open

Disconnect Received - A valid SDLC frame containing a

Write Retry - A previously transmitted I-frame was not

Operation Attempted

Exception

0 0

III

SNRM Received
Disconnect R_eceived_ _ _ _- - - - '
Write Retry
.
Idle Timeout ----------------------------------~

Owrrun-----------------------------~

Underrun------------------------------------~

Connection Problem - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -....
Dump Message - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - '

Figure 3-6. CCA/HPCA SOLC Operation Ending Chart (Code CCCC)

AO/1

0000 0000 0000 0000 0000 0000 0009 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

SY27 -2512-3

3-7

SY27 -2512-3

3-8

Figure 3-7 explains the sense-byte breakdown for CCA!
HPCA SOLC.
Line 2 - NNFF CCCC SSSS SSSS SSSS SSSS
0102 0304 0506 0708
SS bytes are labeled from left to right 5501,5502, SS03, etc.
Location

Bit

Meaning If Bit Is Turned On (1)

CCA
SS01

o
1

2
3
4
5
6
7

SS02

o
2
3

4
5
6
7

5503

o
2
3

4
5

6
7
5504

o
1

3
4
5
6

7
5505

o
1

2
3
4
5
6
7
SS06

o
1

2
3
4
5
6
7

Location

Bit

HPCA

See
See
See
See
See
See
See
See

Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4

Cycle Share Halt
Transmit EOl
Receive Control Entry
Modem/Timer
Exception
Machine Check
Enabled
Interrupt Request

5507

See
See
See
See
See
See
See
See

Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4

Receive Mode
Ping Valid
Pong Valid
Not used
Specif;r. Address Valid
Group Address Valid
Interrupt on Cont Flags
Enable 15 Ones

SS08

See
See
See
See
See
See
See
See

Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4

Invalid Seq/Address
Byte Overrun
Receive Control Entry
15 Ones
Control Overrun
Traffic
Receive Cycle Share Halt
Address in Sync

SS09

See
See
See
See
See
See
See
See

Figure
Figure
F igu re
Figure
Figure
Figure
Figure
Figure

3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4

Transmit Mode
Control Valid
NRZI
load Serializer
Flag
Continuous Character
FCS Seq and Flag
Inhibit Zero Insertion

SS10

See
See
See
See
See
See
See
See

Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure

3-4
3-4
3-4
3-4
3-4
3-4
3-4
3-4

Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Transmit Cycle Share Halt
Byte Underrun

SS11

DTR
RTS
Select Standby
Data Rate Select
local Test
Disable Ring
Disable R LSD
Disable CTS

SS12

Not used
Receive Seq Count
Not used
Not used
Not used
Send Seq Count
Not used
Not used

o
2

3
4

5
6
7

o
1

2
3
4

5
6
7

a
1

3
4
5
6
7

o
1
2

4
5
6
7

o
2
3
4
5
6
7

o
1
2
3

5
6
7

Meaning If Bit Is Turned On (1)

Location

CCA

HPCA

Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used

Timer
Timer
DSR
CTS
DSR Transition
Ring Transition
R LSD Transition
CTS Transition

SS13

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Wrap
T3/T4 Test
New Sync
Tx New Sync
Diagnostic Cloc k
Diagnostic Timer Control
RSlD
Ring

SS14

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Not Used
Not Used
Ptr Reg a
Ptr Reg 1
Ptr Reg 2
Ptr Reg 3
Not Used

SS15

Not Used
Not Used
Ptr Reg 0
Ptr Reg 1
Ptr Reg 2
Ptr Reg 3
Ptr Reg 4

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Data Chain
Frame Chain
Pad Insert
FTA
Xmit Turnoff

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Count 256

a
2

3
4
5
6
7

o
1

2
3
4

5
6
7

o
1

2
3
4
5
6

7
SS16

o
1

2
3
4
5
6
7

o
o

Meaning If Bit Is Turned On (1)

CCA

Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used

Bit

SS17

o
2
3
4
5
6
7

HPCA

Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used

o
Ptr
Ptr
Ptr
Ptr
X

Reg
Reg
Reg
Reg

Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used
Not Used

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Valid Entry
I nval id Sequence
FCS Valid
Pong Entry
Byte Overrun
Buffer Overrun
Flag Received
Count 256

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Count 128
Count 54
Count 32
Count 16
Count 8
Count 4
Count 2
Count 1

Not
Not
Not
Not
Not
Not
Not
Not

Used
Used
Used
Used
Used
Used
Used
Used

Count 256
Count 128
Count 54
Count 32
Count 16
Count 8
Count 4
Count 2

o
Ptr
Ptr
Ptr
Ptr
Ptr

Reg
Reg
Reg
Reg
Reg

0
1
2
3

Count 128
Count 64
Count 32
Count 16
Count 8
Count 4
Count 2
Count 1

Figure 3-7. Sense Byte Breakdown Chart for CCA/HPCA SOLC (Code SSSS)

3.3.5 Test 1 Local Channel Attachment (Model A)
Log
This host adapter log format is returned in response to an
AO/l entry. The format detail is as follows:
Line 1 - Returned the same as input, AO/l.

•

Line 2 - Twenty-four bytes are displayed on this line,
but only 10 are currently used. The individual
bytes are not labeled when displayed. Each
byte is assigned a specific meaning. See the
following example for byte identification:

0000
NNFF

Byte 24
0000
SSSS

0000
BBBB

0000
TTTT

0000
CCEE

0000 }) 0000
XXXX (
XXXX

- This code represents the two low-order digits
of any 500 series nnn number in all cases.

- This byte represents the type of operation
being attempted at the time of the failure. See
Figure 3-8 when FF is to be used.

The counters are not numbered when they are displayed.
They are, however, assigned counter position numbe~rs. The
leftmost 2-digit position is counter number 01, and the rightmost counter position used is counter number 16. The
remaining positions are not used. The value in each counter
is given in hexadecimal. The maximum value for any counter is F~. If any counter is incremented to its maximum
value (FF), it will remain there until reset.

Counter

Meaning

nnn Code*

Command Reject/Not
Initialized
Command Reject
Not Initialized
Bus Out Check (Parity 2)
Bus Out Check (Parity 1
and 2)
Equipment Check
(Parity 1)
Equipment Check
(Parity 1 Modifier)
Equipment Check (Parity 2)
Equipment Check, Control
Logic Machine Check
Data Check
Data Check, Length Check
Connect Received/Already
Connected
Disconnect When PU Was
Active
R U Length Error
Connect Error (Connect
Rejected)
RSOR Received

540

02
03
04
05
06

BBBB - These two bytes represent the number of bytes
received on the last Host Write command.

TTTT - These bytes represent additional adapter status
information. See Figure 3-8.

08
09

- This byte represents the latest counter.

- This byte represents extended adapter information. See Figure 3-8.

Operation
Attempted

Initialize LCA (open)

XX
02

Implied Read
(any value)
Write

Buffer Available

Close (Disable
Adapter Interface)
Write Modified
Purge Write Request

05
06

Each counter is assigned a specific meaning, as follows:

SSSS - These bytes represent the last sense data sent
to the host CPU.

Code

Line 3 - This line displays the statistical counter information associated with this adapter.

•

Description

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

•

Byte 1

There are no completion/error bytes for the LCA.

10
11
12
13
14
15
16

Location

Bit

Meaning If Bit Is Turned On (1)

3
4
5
6
7

Command Reject
Intervention Reqt.ired
Bus Out Check
Equipment Check
Data Check
Not Used
Not Initialized
Not Used

0
1
2
3
4
5
6
7

Data Length Check
Data Reject (not used)
Not Used
Not Used
Parity Check Modifier
Parity Check 1
Parity Check 2
Control Logic Machine Check

Command Accepted
8/370 Status Accepted
Chaining Indicated
Stop
Chaining Canceled
Counter = 0
S/370 Interface Disconnect
Outstanding Status

Right SS Byte

545
546
547
548

Left TT Byte

549
550
512

2
3
4
5
6
7

511
Right TT Byte

410/411
514

2
3
4
5
6
7

Parity Check 1 (control unit parity check)
Parity Check 2 (channel parity check)
370 Interface Disabled
S/370 Status Pending
Adapter Busy
Machine Check
Control Logic Enable/Disable
Interrupt Request in Adapter

0
1
2
3
4
5
6
7

S/370 System Reset
Stacked Status
S/370 Enable/Disable
Selective Reset
Queue Error
Data Abort
Reserved
Reserved

0
1

*See Appendix B for a description of the nnn code listed.
A complete log display for this adapter would appear as
shown below:

EE Byte

AO/1
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

Prepares the data and necessary
controls to transfer data to the
host.
Used to signal the host that buffers are available.
The control code will disable the
host interface in the LCA.
Writes with Buffer Available
Purges outstanding Write requests.

Left SS Byte 1

1
2

541
505
543
544

Initializes the control blocks,
parameters, and buffers needed
by the LCA to support host
communication.

ISee Figures 5-39 and 5-41 (Chapter 5).

Figure 3-8. 3274 Model A Attachment Information
Breakdown Chart

SY27 -2512-3

3-9

3-10

SY27 -2512-3
3.3.6 Test 1 Local Host Attachment (Models B
and D)

Meaning If Bit
Byte Bit Is Turned On
SS

3.3.6.1 Model B
This host adapter log format is returned in response to an
AOl1 entry. The format detail is as follows: ,
•

Line 1 - Returned the same as input, AO/1.

•

Line 2 - Twenty-four bytes are displayed on this line,
'but only seven are currently used. The individual bytes are not labeled when displayed.
Each byte is assigned a specific meaning. See
the following example for byte identification:

Byte 1
0000
NNXX

2
3
4

5
6
7
BB

Byte 24
0000
SSBB

0000
RRHH

0000
FFFF

0000 }
XXXX(

l 0000

xxx X

NN - This code represents the two low-order digits of any
300 series nnn number. The NN byte will be 00 if
the F F byte is OA.
3

XX -Not Used.
SS - This byte represents the adapter sense recorded at the
time of the failure.

BB - The next byte to the right of SS is labeled BB. This
byte represents the adapter basic status recorded at
the time of the failure. See Figure 3-9 for SS and
BB byte meanings.

R R - This byte represents the operation attempted at the
time of the failure. See Figure 3-9 for R R byte
meanings.
HH - This byte represents the hardware state of the adapter
at the time of the failure. See Figure 3-10 for HH
byte meanings.
FF - Engineering use (internal).
•

Line 3 - This line displays the statistical counter information associated with this adapter. If no errors
are recorded for this adapter, the counters will
display as follows:

,Each counter is assigned a specific meaning, as follows:
Description

Command
Reject
Intervention
Required
Bus Out Check
Equipment
Check
Data Check
Unit Specify
Control Check
Operation Check
Signal Device
Causes the LHA to raise interrupt to
End
the host. Set to 1 by control logic and
reset to 0 by the adapter when the
device status for that device is
updated from busy to available.
Signal Device
Causes the LHA device status table to
Busy
be updated to device busy.
Channel
Set to 1 by the LHA during initial
selection when the channel interface
Active
broadcasts the device address to LHA.
Reset t() 0 when the control logic
signals an operation completed.
Metering In
Causes the CPU meter to run (printer
printing). This bit is always on during
a print operation.
End Sequence Set to 1 by the LHA to indicate the
end of a Start I/O CCW sequence from
the channel.
A hardware error was detected during
Adapter
an I/O operation between the adapter
Machine
Check
and the controller.
Online
Allows the LHA (when set to 1) to go
online to the channel. Note: The
Power/I nterface switch must be set to
Interrupt
Request

the Online position.
Identifies the adapter as having raised
I nterrupt Request to the channel.

RR
Code

Byte Definition
Operation Attempted

00
02
04
06
08
OA
OC
OE
1A

Start Sequence
Fetch Device Buffer
Transfer Buffer to Device
Not used
End Sequence
Record Status and Sense
Selective Reset-Unit
System Reset
Local Host Attachment Available

Counter

Meaning

nnn Code*

SSSS contains the sense and status sent to the host.

01
02
03

Bus Out Check
Invalid Sense
Adapter Device Table Parity
Error
Cycle Share Machine Check
Recoverable liD Error
(not cycle-share)

551
351
355

LL contains error log data.

04
05

The counters are not numbered when they are displayed_
They are, however, assigned counter position numbers. The
leftmost 2-digit position is counter number 01, and the
rightmost counter position used is counter number 05. The
remaining positions are not used. The value in each counter is given in hexadecimal. The maximum value for any
counter is F F.

356

*See Appendix B for a description.
A complete log display for this adapter would appear
as shown below:
AO/1
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
Description

Bit

Meaning If Bit Is Turned On

HH Byte

0
1
2
3

Mode of operation *
Mode of operation *
Not used
1 = Large screen size, 0 = Small
Reserved
Not used
WCC only
Not used

6
7

* 10= Type B device operation
01 = Type A device operation
11 = Type B/Katakana device operation
00 = 3272 device type operation

ZZ contains the metering-in count, which is the number of
printers that have device end (print complete pending).

,XX is for engineering use (internal).
(A detailed description of these bytes follows the line 3
description.)
•

Line 3 - This line contains statistical counter information associated with the adapter. If no errors
are recorded, the counters will be zero. The
counters are not identified (numbered) when
displayed. The leftmost 2-digit positions
represent counter 1, the next 2-digit positions
represent counter 2, and so on. The value of
each counter is represented in hexadecimal
and can contain a maximum count of FF.
The counters do not wrap.
Each counter is assigned a specific recording
function, as follows:
Counter

Meaning

Comments*

01
02
03

Command Rejects
Operation Checks
Adapter Detected
Data Checks
Bus Out Check
Cycle Share Error
Unexpected
Adapter Requests

nnn Code 401
nnn Code 402, 404, 406
nnn Code 364

Figure 3-10. HH Byte Definitions

04
05
06

3.3.6.2 Model D

*See Appendix B.

This host adapter log format is returned in response to an
AOll entry. The format detail is as follows:
•

Line 1 -

Same as returned by an input of AO/1.

•

line 2 -

Twenty-four bytes are displayed on this line,
but only 10 are currently used.

Byte

0000 0000 0000 0000 0000 0000 0000 0000 0000 0000
Figure 3-9. 3274 Model B Operation Attempted Chart
(Code RR)

CC is the command code received from the adapter.

NNDD AAAA RRCC SSSS LLZZ XXXX '" XXXX
0 0 00
00 00 01
1
22
2 3 4
5 6
7 8 9 0
2 '" 90

Following is a detailed description of the line 2 bytes:
Byte

Bit

Meaning If Bit Is Turned On

AAAA
(bytes 3
and 4)

Channel Stop - The SLHA detected a channel stop before all the data was transferred to
the host. (The host CCW byte count did not
allow a full transfer,)
Chaining Indicated - The SLHA detected
that the channel is performing a Command
Chaining CCW operation.

Odd Byte Transferred - The SLHA traASfer red an odd number of bytes to the control
unit as a result of a Write CCW operation.

o
o
o

Where:
NN represents the two low-order digits of any 300 series

nnn code.
DO contains the device (port) address selected at the time
of error.

AAAA contains the status received from the adapter.

RR is the request code presented by the adapter to the
control logic.

nnn Code 551
nnn Code 362

Byte

Bit
8

Request in Progress - An SLHA request is
pending (RR byte) for processing by the
control logic.

Allow Online - The control logic has
requested the SLHA to go online.

Quiet Control - The control logic has
asynchronous status to present to the
channels.

Metering In - Causes the CPU meter to ru n.
Metering In is set on while any attached
printer is printing (busy) and is turned off
when all printing operations are finished.

Online - The SLHA is online (bit 9 is set,
the Online/Offline switch is in the Online
position, and there is no channel activity).

Adapter Machine Check - The adapter has
detected a machine check during cyclesharing operations (see counter' 5).

14
15

Byte

Meaning If Bit Is Turned On

Byte
Value

Interrupts Enabled - The SLHA is allowed
to interrupt (via bit 15) the control unit.

Byte
Value

Meaning of Byte Value

01
02
03
04
05
06
OB
00
OF
11
1B
2B
38
4B
E4

Write
Read Buffer
No-op
Sense
Erase/Write
Read Modified
Select RM (Read Modified)
Erase/Write Alternate
Erase All Unprotected
Write Structu red Field
Select RB (Read Buffer)
Select RMP (Read Modified from Position)
Select RBP (Read Buffer from Position)
Select Write
Sense 10

Byte

Bit

Meaning If Bit Is Turned On

SSSS
(bytes
7 and 8)
Byte 7

Command Reject
Intervention Required
Bus Out Check
Equipment Check
Data Check
Unit Specify
Control Check
Operation Check

Byte
CC
(byte 6)

Interrupt Request - The SLHA has raised
Interrupt Request to the control unit.

Diagnostic Channel Response (Bring up test only should not be active during normal operations).

Waiting for Channel End - The control logic
has detected a device error during a Read
CCW operation and has requested control
at the conclusion of the data transfer in
order to record the error status.

End Sequence - The adapter has encountered the end
of a CCW chain (end sequence will follow the last
command-loaded request).
Waiting for Device End - The SLHA has transferred
the last block of data to the control unit for a channel
write operation and is waiting for the control logic to
signal device end.

This device adapter log format is returned to the requesting
3278 in response to an A 1/1 entry. The format detail is
as follows:

2
3
4

5
6
7
LL
(byte 9)

0
1
2
3
4
5
6
7

Adapter Online - The SLHA has gone in the online
state.

Clear for Interrupts - The SLHA is ready for the control logic to present asynchronous status (the channel
is quiet).

System Reset - The SLHA has detected a System
Reset condition on the channel (see nnn code 505 in
Appendix B).

Command Loaded - The SLHA has received a CCW
command from the channel.

Selective Reset - An interface disconnect or Halt I/O
condition from the channel has been detected by the
SLHA (see nnn code 503 in Appendix B).
Data List Stop - The SLHA has just transmitted
(Read CCW) or received (Write CCW) a block of data
and is notifying the control logic of this condition.

Left 0
SS
Byte

•

Line 1 - Returned the same as input, A 1/1.

•

Line 2 - Ten bytes are displayed on this line, but only
three are currently used. The individual bytes
are not labeled when displayed. Each byte is
assigned a specific meaning. See the following
example for byte identification:

Meaning If Bit
Is Turned On

NN represents the two low-order digits of any 200 series
nnn number. The nnn number mayor may not be
displayed on a 3287.
XX is not used.

SSSS represents the adapter status associated with the last
failure. See Figure 3-11 for SS byte meanings.

Attention
Status Modifier
Control Unit End
Busy
Channel End
Device End
U~it Check
Unit Exception

•

Command Reject
Intervention Requ ired
Bus Out Check
0
Data Check
0

0
0

See nn code 202 in Appendix B.

Read
Timeout

The DCA expected data or a response
from the device while executing a command sequence and did not receive it
in a predetermined amount of time.

Turnaround
Error or Read
Line Parity

The DCA detected a coax turnaround
sequence error or a coax parity error
while executing a command sequence.

Read Data
Byte Parity
Error

The DCA detected a parity error in the
data transmitted by the device.

Stop Poll

The DCA is not polling.

Timer

The DCA timer has fired. The timer is
of 1 to 4 seconds' duration and is used
primarily to check for a hung device.

Error Q
Entry

The DCA has detected error status
while communicating with or from an
attached device and has stored this
information in the Error Q in the
3274.

Not used

There are two types of device adapter log. The log for
Category A devices is accessed by using an A 1/1 format.
The information returned in the log consists of the last
nnn number recorded, some basic adapter status information at the time of the failure, and statistical counters
similar to the device error log counters. The log for Category B devices is accessed by using an A2/1 format. The
information returned in the log consists of the last nnn
number recorded, the operation being attempted at the
time of the failure, and information in byte form as to how
the operation ended. There are also statistical counters
similar to the device error log counters. The above log
information should be used to determine the type of error
condition that is disabling either of these device adapters.

Right 0
SS
Byte

Line 3 - This line displays the statistical counter information associated with this adapter.

Extended
Status Data

The DCA has set information in extension (left SS byte) status.

Command
Completed

The DCA has completed a commanCl
sequence with a device.
The DCA is active performing an
operation.

0000 0000 0000 0000 0000

Adapter
Active

The counters are not numbered when they are displayed.
They are, however, assigned counter position numbers. The
leftmost 2-digit position is counter number 01, and the
rightmost counter position used is counter number 08. The
remaining positions are not used. The val ue in each counter is given in hexadecimal. The maximum value for any
counter is FF. If a counter is increased to its maximum
value (FF), it will remain there until reset.

Keystroke or
The DCA has polled a device, has
Status Q Entry received a keystroke or status, and has
placed the data in a Q in the 3274.

Not used

Machine
Check

The DCA has detected an error in
itself or on the I/O bus.

Enablel
Disable

The DCA is enabled for operation.

Interrupt
Request

The DCA has caused an interrupt
request.

Each counter is assigned a specific meaning, as follows:

3.3.7 Test 1 Device Adapter Logs

Description

Counter
Overflow

0000 0000 0000 0000 0000
NNXX SSSS XXXX XXX X XXXX

Adapter Offline - The adapter has just been put in an
offline state (see nnn code 501 in Appendix B).

Byte Bit

3.3.8 Test 1 Type A Adapter Log

Meaning of Byte Value
Byte 8

RR
(byte 5)

1
2
3
4
5
6
7

The logs can be used in the same manner as the host
adapter logs to determine (1) what the frequency of error
is, (2) what the adapter was doing at the time of error,
(3) how the operation ended, etc.

Counter

Meaning

nnn Code*

Status Q Entry Placed in
Error Q
Unconfigured Device
Command Complete without
an Operation in Process
Invalid Adapter Status
Lost Status due to 202 Error
Adapter Stepped and
Restarted
Cycle Share Machine Check
Non Command Cycle Share
Machine Check

292

02
03
04
05
06
07
08

Figure 3-11. Sense (SS) Byte Definitions

293
294
295
296
297
298
299

*See Appendix B.

SY27-2512-3

3-11

3-12

SY27-2512-3·
3.3.9 Test 1 Type B Adapter Log
This device adapter log format is returned to the requesting
3278 in response to an A2/1 entry. The format detail is as
follows:
•

Line 1 - Returned the same as input, A2/1.

•

Line 2 - Ten bytes are displayed on this line, but only
four are currently used. The individual bytes
are not labeled when displayed. Each byte is
assigned a specific meaning. See the following
example for byte identification:

0000
NNFF
NN

CCCC -

0000

eccc

0000
XXXX

0000
XXX X

pp is the count of storage parity errors encountered for

FF
Code

Operation Attempted

00
1F
21
23
26

Initialize (Enable and Start Idle Poll)
Read Full Buffer without Start Idle Poll
Specific Poll without Start Idle Poll
Start Idle Poll
Write Full Buffer without Start Idle Poll

Figure 3-12. Type B Adapter Operation Attempted Chart
(Code FF)

0000
KKSS

Location

Bit

Meaning If Bit Is Turned On (1)

Left CC Byte

0
1
2
3
4

Retry Count 1
Retry Count 1
Retry Count 1
Retry Count 1
Complete-Operation terminated
Error (Unrecoverable error encountered)
(See Right CC Byte for detail)
Exception (An attention was received
before the idle poll could be stopped to
perform the operation-val id only if
Attention is on also)
Attention

This code represents the two low-order digits of
any 200 series nnn number. The nnn number
mayor may not be displayed on a 3278.

5
6

This represents the operation being attempted at
the time of the failure. See Figure 3-12 to determine the type of operation in progress at the
time of failure.

These two bytes indicate how the operation
attempted ended. See Figure 3-13 for this
information.

Not applicable

Centurion NN number.

Centurion status associated with error NN.

MM Machine
Check

AA Adapter
Overrun

0000
XXXX

2
3
4
5
6

• Line 3 - Three bytes are displayed, which identify
machine check, adapter overrun, and unconfigured device interrupt.
0000
0000
MMAA UUXX

Right CC Byte

0000
PPEE

An adapter machine check was encountered on an adapter I/O operation. If recovery is not successful,
an nnn code of 270 is logged (see
Appendix B).
An adapter request for service was not
honored by the control unit within
the required period of time. If recovery
is not successful, an nnn code of 272 is
logged (see Appendix B).

UU Unconfigured An interrupt was received from a device
Device
(coax port address) for which a DCB has
Interrupt
not been configured.

Not applicable

Encryption Key Parity Errors

Encryption Adapter Errors

7
1

Overrun
Parity Error on Serial Interface
Device Not Available
Busy
Adapter Disabled
Machine Check
Idle Poll On
Invalid Operation Attempted

Number of times current operation retried

Figure 3-13. Type B Adapter Operation Ending Chart
(Code CCCC)

3.3.10 Control Logic Error Log
The control logic error log format is returned to the requesting 3278 in response to an A3/1 entry. The format detail
is as follows:
•

Line 1 - Returned the same as input, A3/1.

•

Line 2 -Eight bytes are displayed on this line, but only
seven are currently used. The individual bytes
are not labeled when displayed. Each byte is
assigned a specific meaning. See the following
example for byte identification:

0000

cepp

0000
0000
MMRR HHDD

00
AAXX

. Where:

CC represents the number of cycle-share I/O errors
encountered. The count is incremented when a cycleshare error occurs. The counter will not wrap (increments to FF and then stops). For detailed log information on the associated adapter, see Adapter Logs
AO/l-A2/1.

which recovery was successful. The counter will not
wrap (increments to FF and then stops).

Page 2
4041 4243 4445 4647 4849 4A4B 4C4D 4E4F
0000 0000 0000 0000 0000 0000 0000 0000

MM represents the control logic machine checks encountered for which recovery was successful. The counter
will not wrap (increments to FF and then stops).

5051 5253 5455 5657 5859 5A5B 5C5D 5E5F
0000 0000 0000 0000 0000 0000 0000 0000

RR is a reserved byte.

6061 6263 6465 6667 6869 6A6B 6C6D 6E6F
0000 0000 0000 0000 0000 0000 0000 0000

HH is a machine check threshold counter for the host
adapter. The count is incremented when an adapter
I/O machine check occurs. The counter will not wrap
(steps to F F and then stops).
DO represents the Type A adapter machine check threshold
counter. It increments in the same manner as HH.

AA represents the Type B adapter machine check threshold
counter. It increments in the same manner as HH and
DD.

XX is used as the Encrypt/Decrypt adapter machine check
counter. This counter increments in the same manner
as HH.
•

Line 3 -

There is no line 3 assigned to this log; however, a third line might be displayed if this
log was entered from another log display.

7071 7273 7475 7677 7879 7A7B 7C7D 7E7F
0000 0000 0000 0000 0000 0000 0000 0000
The subsystem configuration for your machine can be
determined from Figure 3-14.
Byte 10

Feature Level }
See bytes
System Level
70-75
Language level
I nterface Adapter
01
LCA (MadellA)
02 LHA (Model 1 B)
1)4 HPCA/CCA (ModellC)
08 SLHA (Model 1 D)
41
LCA (Models 21A, 31A)
42 LHA (Model 21 B)
44 HPCA/CCA (Models 21C, 31C)
48 SLHA (Models21D,31D)
84 Model51C
Channel Address
(Model A)
I nternal Flag
00 Not Model A
01
Model A
line Code
01
EBCDIC
02 ASCII
line Control
01
BSC
02 SDLC
BSC Poll Address

BSC/SDlC Select Address

Communication Adapter
01 CCA
02 HPCA
04 Encrypt/Decrypt
10 Printer polled from host
Remote Attachment
01 Wrappable Modem
02 DDS Adapter
04 X.21 Leased
08 Greater than 1200-bps Integrated Modem
10 X.21 Switched
20 Loop (Model 51C only)
40 EMI Switched
80 1200-bps I ntegrated Modem Nonswitched
(Model 51C only)

02
03
04

3.4 TEST 2: DISPLAY CONFIGURATION
INFORMATION
Test 2 displays the configuration table residing on the system diskette. The configuration table data is the result of
the user customizing the feature diskette and writing the
configuration data from storage to the system diskette.
Test 2 is displayed by entering Test mode by means of the
AL T and TEST keys and then keying in slash (I), two (2),
and ENTER. You may page from one display to another
by pressing the ENTER key.
The bytes displayed are labeled by position number. The
following format shows the configuration bytes labeled.

05
06

XXI

Page 1
0001 0203 0405 0607 0809 OAOB OCOD OEOF
0000 0000 0000 0000 0000 0000 0000 0000
1011 1213 1415 1617 1819 1A1B 1C1D 1E1F
0000 0000 0000 0000 0000 0000 0000 0000
2021 2223 2425 2627 2829 2A2B 2C2D 2E2F
0000 0000 0000 0000 0000 0000 0000 0000
3031 3233 3435 3637 3839 3A3B 3C3D 3E3F
0000 0000 0000 0000 0000 0000 0000 0000

Description
Diskette Type
D4 Feature
E2 System
D3 Language
D9 RPQ Diskette

XX)

1 XX = 2 hexadecimal digits

Figure 3-14 (Part 1 of 2). Subsystem Configuration

Byte 10

Description

Byte 10

Description

Byte 10

Description

TP Options
01 Omit Answer Tone
02 Point to Point
04 Half-5peed
08 Select Standby
10 Special Request to Send 2
20 Nonswitched Line
40 NRZI
80 WT DCE Sw Network

Type A Dr/Rcvr
00 None
02 1st Card
04 2nd Card
06 3rd Card
08 4th Card

Patch 10 Values

Part Number and EC Level of 2nd RPQ Installed
(7-digit PN, 3-digit EC Level)

M!QS V,2i cix,x,x,x ~x ~;;!~c;~::cePt

59
,J,
50

Total All Terminals
XXi

Part Number and EC Level of 3rd RPQ Installed
(7-digit PN, 3-digit EC Level)

Reserved (Model 51C only)

EBCDIC BSC CU 10
XXI

Reserved

51C,52C)

Model No. All Models

3(32R)

Control Storage Addition
02 M1X VO
C2
04 M1X VO
C3

2(16)
4(32)

E2
E2

Control Storage Addition
02 M1X VO
C3

2(16)

Control Storage Addition
04 M1X V1
C1

4(32)

2(16)

Reserved

Optional Code Select
01 3289 Text Print Control
02 Between Bracket Sharing
40 1063 Auto Entry Magnetic Slot Reader
80 1063 Magnetic Slot Reader

Optional Code Select
01 SCS Printer Support not present
02 Host Loadable PAM not present
. 04 Local Copy not present
10 Magnetic Slot Reader not present

1 XX

Type B Dr/Rcvr
00 None
01 1st Card
02 2nd Card
03 3rd Card
04 4th Card

Extended Function Store Response (1st two digits)

,J,
05

Reserved

,J,
6F

Reserved

Physical Unit Identification Number

Total DCB Count
XXi

70
71

Feature Diskette Level and Suffix

Print Authorization Matrix Entry Count
XXi

System Diskette Level and Suffix

Storage Extension
01 Not Installed
02 Installed
82 Installed

Language Code
See the 3274 Planning, Setup, and Customizing
Guide, GA27 -2827

,J,

'A' DCB Count Response

Keyboards
01 Typewriter
02 Data Entry
04 Data Entry II
08 APL
10 Text

Extended DCB Count

Attribute Select Typewriter Keyboard
01 Color Heads Present
02 P Heads Present

74
75

Language Diskette Level. and Suffix

EC Level and Suffix Level of 1st RPQ Installed

77
78
79

EC Level and Suffix Level of 2nd RPQ Installed

7A
7B

EC Level and Suffix Level of 3rd RPQ Installed

Magnetic Responses
00 None
01 Numeric (3277~ompatible)
02 Alphameric (auto entry for nondisplay data)
03 Alphameric (auto entry for all data)

Attribute Select Control Unit Options
01 SFAP (EDS) Present
02 Decompression Present

Reserved

Validation Number

Reserved

,J,
30

Reserved

3D
Reserved (Model 51C only)

Reserved

Reserved (Model 51C only)

Attribute Select Typewriter Keyboard
(PS, Extended Highlighting, Color)
00 No Attribute Select Typewriter Keyboards
being Used.
01 Attribute Select Typewriter Keyboards without
the Numeric Lock Feature.
02 Attribute Select Typewriter Keybo.ards with the
Numeric Lock Feature (4690).

•

Line 1 - 0123456789012345, 6789

•

Line 2 - 1111111111111111

•

Li ne 3 - 0000 0000 0000 0000 0000

110-

Line 1 displays all the Category A devices, starting from
the leftmost position. The digits correspond to the loworder digit of the coax port address. Therefore, port
AO = position number a and port A 15 = position number
15. The Category B devices are separated from the
Category A devices by a space. Therefore, port BO = position number 16 in the log and port 803 = position
number 19.
Line 2 displays the status (1
of each configured device.

= on, a = off, and - = disabled)

Line 3 displays statistical counter information in summary
form of control-unit-detected machine checks, communication checks, program checks, and SOLC test commands.
The values are displayed in hexadecimal. The counters are
two-byte counters numbered from left to right starting at
counter number 01. See the following example for counter
meanings:
Counter

Meaning

0102
0304
0506
0708
0910

Summary of all machine checks
Summary of all communication checks
Summary of all program checks
SO LC test commands received
SO LC test commands sent
(Maximum counter values are FFFF)

Use the associated error logs(device/adapter) to further
define the summary counters. The maximum value of the
counters is FFFF. If a counter is incremented to the maximum value, it will remain there until reset by an IML or
A3/4 test.

,J,
3F

Test 3 is invoked after the AL T and TEST keys are used to
enter Test mode. An entry of /3 from any functioning
3278 display, and then an ENTER, will display one of the
following formats on the screen (the actual format may
vary depending on how many devices have been
confi gured) :
Example 1:

XXl

Control Storage Base
04 M1X VO
C1

Control Storage Addition
02 M1X Vl
C2

Part Number and EC Level of 1st RPQ Installed
(7-digit PN, 3-digit EC Level)

,J,

Total Category A Terminals
XXi

Configuration Byte Value

Card No. (1,2,3,4)

Number of RPQs Installed

Volume No. (1,2,3)

Total Category B Terminals
XXI

Card Type

Legend for Bytes OE-12

.22$.

3.5 TEST 3: DISPLAY THE STATUS OF ALL
CONFIGURED TERMINALS AND DISPLAY
THE CONTROL UNIT SUMMARY COUNTERS

= 2 hexadecimal digits.

2 Active

fromSTXto EOT for BSC, 4-wire, multipoint.

Figure 3-14 (Part 2 of 2). Subsystem Configuration

SY27-2512-3

3-13

SY27-2S12-3
Example 2:

Line 8. consists of control unit statistical summaries.
(Refer to Line 3 of example 1).

(Machine configured for 32 devices)
•

Line 1 012345678901234567890123

45678901

•

Line 2 10111111111011111-1111111

11011001

•

Line 3 ddddddddddd-dddddddddddd pdpdpdpd

•

Line 4 ........

I.. . . . :. I..... I. . ... * .. .
*

•

Line 5

•

Li ne 6 ++++++++++

•

Line 7

•

Line 8 0000 0001 0000 0000 0000

+++++++++++ ++++ +++

Line 1 shows coax port addresses (0-31). In this example,
the 3274 is configured for 32 devices (24 Category A and
8 Category B devices). Category A devices are always
shown first.

= Device

powered on
o = Device recognized as powered off
- = Device recognized as disabled because of control-unitdetected errors

3.7.1 Test 6 Byte Identification
Figure 3-15 identifies the bytes of the DeB displays.

3.6 TEST 4: RESET ANY TEST 1 LOG
First Display

Test 4 provides the capability of resetting any device
adapter, device, host adapter, or control logic log. By
using the AL T and TEST keys, you may enter Test mode.
Test 4 may now be used as shown below:
•

00 to 31/4 - Resets the device log for the device specified to all zeros (0)

XX/6 - Returned as input

Any device

000 - ID of the first address of this display
ID only

000
010
020
030

2 3

4 5

6 7

8 9

0000
0000
0000
0000

ABC D E F -

0000
0000
0000
0000

•

AO/4 - Resets the host adapter log to all zeros (0).

•

A1/4 - Resets the Type A adapter log to all zeros (0).

•

A2/4 - Resets the Type B encrypt adapter log to all
zeros (0).

Second Display

A3/4 - Resets the control logic log to all zeros (0).
Also resets the LEOs.

040 - I D of the first address of this display

•

Line 2 shows the status of each device, where:
1

3-14

Test 4 may be used to track intermittent failures without
re-IML or powering off the machine to clear the error logs.

ID only, not displayed

0000
0000
0000
0000

Byte 3F

0000
0000
0000
0000

Byte 7F

0000
0000
0000
0000

Byte BF

0000
0000
0000
0000

Byte FF

XX/6 - Returned as input

040
050
060
070

0000
0000
0000
0000

3.7 TEST 6: DEVICE CONTROL BLOCK
DISPLAY

Third Display

The device control block (DeB) contains common subsystem information pertaining to all terminals, device and host
adapter information, and limited device-feature information. The Test 6 display represents the most current information regarding a specific device. The DeB should be
checked when it is necessary to determine specific device
parameters such as: (1) Is the device configured as a display
or printer? (2) Is the display screen size correctly specified?
(3) Is an MDT bit set? (4) The status of keyboard for this
device and so on.

080

0000
0000
0000
0000

XX/6 - Returned as input

Line 3 shows the type of device attached, where:
d = Display
p = Printer
i = Other
- = Never initialized
Line 4 shows a summary of coax errors, where:

· = No errors
; = 1-9 errors

1= 10-19 errors
* = 20 or more errors
Line 5 shows a summary of device errors, where:

· = No errors
: = 1-9 errors
10-19 errors
= 20 or more errors

Line 6 shows a summary of sessions bound (this line will
appear only for SNA attachments), where:

+ = Session bound
blank

= not session

bound

To invoke Test 6, you must first enter Test mode by means
of the ALT and TEST keys. The DeB for any device from
00 to 31 may be displayed by keying the device number
followed by a slash (/), the number 6, followed by an
ENTE R key. Each DeB consists of four displays of 64
bytes each. The individual bytes are not labeled. There
are six lines to each display. The first line is always
returned the same as input 00-31/6 for each display. The
second line of each display will indicate the beginning byte
ID of that display. See Figure 3-15 for details. You may
page from one display to the next by pressing the ENTER
key. Paging beyond display OC will result in a locked
keyboard and X-f displayed on. the status line. See Figure
3-16 for DCB interpretation. When Extended DeBs are
configured, there are four more blocks to examine.

080
090
'OAO
DBa

- ID of the first address of this display
0000
0000
0000
0000

0000
0000
0000
0000

Fourth Display
XX/6 - Returned as input
DCa
DCa.
ODD
OED
OFO

- ID of the first address of this display

0000
0000
0000
0000

Figure 3-15. Test 6 Byte I D Chart

0000
0000
0000
0000

3.7.2 DeB Bit Definitions
Bytes not defined in Figure 3-16 are not used. Bits defined
as "Reserved for engineering use" may contain zeros or
ones. They should be disregarded unless otherwise directed
by the next level of the support structure.
Location
Byte 02

Bit
0
2

3
4
5

6
7

Display
Model

Location

Meaning If Bit Is Turned On

Byte 06

}

See Figure A

}

See Figure B

0..-0

~.c
.- >
'- 0>
~~
0> '

...

Figure A

2
3
4
5-7
0
2

3
4

5
6
7
Byte 04
(Category B
Devices)

0
1

2
3
4

5
6
7
Byte 05
(Category A
Devices)

....

...

Byte 04
(Category A
Devices)

« ...

6
7

....i

Bit

Byte 03

0
1
2
3
4

Keyboard is attached
This is a Type B device
Numeric Lock feature is present
~

Bit

(1l

Figure B

Byte 07

c.~
/-/-

3
4

6
7

a..

>0>

Byte 08

Katakana keyboard is attached
SCS feature on Type A adapter printer
Text keyboard
3289 Text feature
APL keyboard
Reserved for engineering use

2
3
4

5
6
7

Not used
Security keylock present
Selector pen attached
Reserved for engineering use
MSR/MHS attached
Reserved for engineering use
Reserved for engineering use
ECS (APl/Text)

Byte 09

Device busy
Buffer parity
Indeterminate write errors
Inhibit start idle poll
Buffer size (0=480, 1=1920)
DAU issued
Start print

Byte OB

0
2
3
4
5

6
7
0
2
3
4

5
6

Format bits
Convergence (3279)

0
1

7
Byte OC

0
1

2
3
4

5
6
7

Meaning If Bit Is Turned On

Location

Bit

Meaning If Bit Is Turned On

DCB busy
Subsystem ready (DCB initialized)
Nondisplay
Op Complete pending from device
Linkage stacked
Stacked status/keystroke/error present
Numeric Lock field
Reserved for engineering use

Byte 00

Printer printing - local copy
If display has printer assigned for local copy
Printer matrix changed (associated with this display)

Protected field or attribute character
ECS buffer updated
Pri nt 10 entry mode
Reserved for engineering use
MDT bit not set
Do not enter
Reserved for engineering use
Insert mode
No indicators to write or erase (Category B
displays and printers, Category A printers)
Test mode
Alpha shift (not Katakana shift)
Reserved for engineering use
Text indicator
Upshift indicator
Katakana shift
APL indicator
Online indiCator
System-wait condition
Hard-lock condition
Keyboard in use by operator
DCB scheduled for function 6 - waiting (BSC)
DCB scheduled for function 5 - waiting (BSC)
Reserved for engineering use
OK for function to be suspended
Reserved for engineering use
Reserved for engineering use
Reserved for engineering use
Local copy (display to printer) in progress
Alternate screen size
Attributes not valid
Monocase switch active in device
Reserved for engineering use
Printer messages queued - local copy
Reserved for engineering use
Local copy malfunction has occurred
Go elsewhere
Minus Function
MSR/MHS - wrong card
Message pending
Message reminder

2
Byte OE

0
1

Invalid dead key (language 06 only)
2NN machine check
Communication check
Program check
Security key off
3NN machine check

6
7

Too much (keystroke-MSR)
Operator not authorized

Not enough
Wrong number
Numeric shift
Operator retry
Local-copy failure while printer printing (printer failure)
Device busy doing local copy
Reserved for engineering use
System lock (X System)

2
3
4

Byte OF

3
4
5
6
7
Byte 10

Communication check reminder
My Job indicator
System Operator indicator
Unowned indicator
Not enabled (·not online)
Reserved for engineering use
Reserved for engineering use

Minus Syml;>ol indicator (WT only)

20
22
24
26
28
2A
2C
2E
30
32
34
36
38
3A
3C
3E
40
44

Request search
Erase input (active partition only)
Erase unprotected to address
Reset MOTs
Clear buffer
Erase partition
Write head control register
Inhibit keyboard
Write indicator
Erase indicator
Write machine check
Write communication check
Write application program check
Power terminal off
Terminal reset
Reset keyboard
End of Type B buffer transfer

2
3
4
5

Byte 13
Bits 0-7

46
48
4A
4C

Clear programmable character set
Command queue exeCution
Image execute command Q and suspend L5
Image execute command Q and suspend L6
Start print

Figure 3-16 (Part 1 of 2). DCB Bit Definition Chart

SY27 -2512-3

3-15

SY27-2512-3

Location

Bit

Meaning If Bit Is Turned On

Byte 3C

2nn

Byte 3D

3nn

Byte6A
(Category A
devices)

Byte 3E

4nn

Byte 3F

5nn

0
1
2
3
4
5
6
7

Shift/Numeric Lock key still depressed
ALPHA key depressed
Alternate Shift key depressed
Shift/Numeric Lock key in effect
Left Sh ift key
Right Shift key
Katakana Shift key depressed
In APLlText shift

0
1
2
3
4
5
6
7

Reserved for engineering use
Local copy being printed
Reserved for engineering use
Local copy delayed indicator
Printer in shared mode
Printer in local mode
Printer mode change
Reserved for engineering use

3.10 3277 PATH TEST AND TEST REQUEST
KEY

Byte 70

Local copy printer I D

Test Request key will cause the control unit to attempt to

Byte 71

Local copy printer address

Bytes 76, 77

Printer DCB Devices 0-15, ones in this
field are authorized to use this printer.

Bytes 78, 79

Printer DCB devices 16-31 (same as byte 76
and 77 description)

Bit

Meaning If Bit Is Turned On

Location

Byte 13
Bits 0-7

4E
50
52
54

Host printer available for local copy
Local copy request
Type B read buffer
Type B write buffer
Type B write buffer and sound alarm
Type B sound alarm
Type B intermediate write (DSE)
Type B level 5 lock (PCM)
DCA printer abort request
DCA printer system status order

50
Bytes 14, 15

Cursor position (3278 only)!

Bytes1A,1B

First character position on display 1

Bytes 1C, 1D

Last character position on display I

Byte 24
(Category A
devices)

0
1
2
3
4
5

6
7
Byte 25

3
4

Model 5 wide screen
Model 5 wide screen
480-character format
Reserved for engineering use
Inhibit display video
Blan k cursor
Cursor reverse
Cursor blink
APL mode
AP L attached

Byte 26

Row length

Byte 27

Indicator row length

Byte 29

AID Code

Byte 31
Bits 0-7

00
10
20

2K
4K
8K

Byte 34

SNA - printer allocated to local copy
SNA - local copy printer allocated for host use.
SNA - host request for local copy allocated printer
Alternate row length indication
Default row length indication
Reserved for engineering use
SNA - LU in ERP state
SNA - host communication disabled (LU active)

Byte 46

Byte 47

Bit

0
1
2
3
4
5
6
7

Byte 35

0
1
2
4

Local copy printing (host-initiated)
Local copy printer available (display only)
Local copy (printer available for next message) SNA
FM data received for display queued for
local copy

When using this byte on Category A devices, subtract hex 50 from
the cursor position. This will give you the current I/O interface
code (if Model 1, subtract X"40").

Figure 3-16 (Part 2 of 2). DCB Bit Definition Chart

Other function request
Select pen for immediate detect field
Required for Select Pen field
Dup Key switch (auto tab)
Reserved for engineering use
Clicker enabled
Print 10 Entry mode
Type B erase all unprotected

Disable cursor display
Local copy buffer transfer in progress
Second local copy requested
Dead key sequence in process
Local copy received I R

Byte 4E
(Category A
devices)

0-7

Attribute affecting field cursor (3278 only)

Byte 4E
(Category B
devices)

0
1
2

0
1
2
5

2
3
4
5
6
7

3.8 TEST 7: DYNAMIC CONVERGENCE
(COLOR)

Meaning If Bit Is Turned On

Location

58
2E
5A
5C

3-16

5
Byte 4F
(Category A
devices)

0-7

Byte 4F
(Category B
devices)

0
1
2
3-7

Device check
Transmit check
Information pending
Not ready (printer only)
Equipment check (printer only)
Current Extended Field Attribute
(Configuration Support Conly)

Device busy
Buffer size (0=480, 1=1920)
o = display, 1 = printer
Device address (type B adapter port number)

Bytes 50, 51

Present attribute address (3278.only)1

Bytes 52, 53

Next attribute address (3278 only)1

Byte 68

2
3
4

5
6
7

Printer equipment check/display disabled
because of error
Intervention required/security key off
Printer busy processor abort
Reserved for engineering use
Print in process
Start print pending
Printer disabled
Reserved for engineering use

Byte 6B

For a description of this test, see the IBM 3279 C%r Display Station Maintenance Information manual, SY33-0069.

3.9 TEST 8: PS, HIGHLIGHTING, AND COLOR
For a description of this test, see the IBM 3279 Color Oisplay Station Maintenance Information manual, SY33~OO69.

3.10.1 BSe or Local Host Attached
On 3277s attached to a BSe or local host attached 3274,
the coax path from the device to the control unit can be
verified by means of the Test Request key. Pressing the
turn on the System Available indicator on the 3277. A
Test Request message will also be generated if the control
unit is online to the host.

3.10.2 SNA Attached
On 3277s attached to an SNA-configured 3274, the coax
path from the device to the control unit can be verified by

Bytes 7A, 7B

Printer class assignments (printer only)
1 in one or more bits (0-15) represents
printer class assignments 70-85

means of the Test Request key twice. The first pressing of
the key will cause the control unit to attempt to turn off
the Do Not Enter indica·tor; the second will cause the con-

Byte A2
Byte B4
(Model
C,8SC)

wec save area
0;; Device End posting required
5 ;; Error on BSC copy command

trol unit to attempt to turn on the System Available indicator. Operationally, th is sequence is used to enter and
exit 2-key sequence mode. Test Request followed by Clear
is functionally equivalent to the Systems Request key on
32785 in SNA mode. T~st Request followed by PA 1 is the

Byte B4
(Model B)

WCC from host

Byte 86
(Model BSC)

Pending device status

Byte B9
(Model
C, BSC)

Line address this device

Byte BA

5 = Dual Case
6 = Mono Case

Bytes DC·DD

Defau It screen size

Bytes DE-DF

All screen size

equivalent in function to the ATTN key on ::!278s in SNA
mode. Test Request followed by Test Request returns the
3277 to normal operation.

Chapter 4. Subsystem Tests, External Tests, and Subsystem Service Aids
4.1 INTRODUCTION
Subsystem tests consist of the Bus and Lamp test and the
IML tests. External tests consist of OLTs for Models A, B,
C, and D.

4.2 INITIAL MACHINE LOAD (lML) TESTS
Initiating a normal IML (ALT switch not pressed and system diskette installed) invokes a sequence of hardware tests
before operational code is loaded. When the 1M L pushbutton is pressed, a hardware Bus and Lamp test is performed.
When the IML pushbutton is released, the diagnostic
sequence begins and the error indications described in
Figure 4-1 may be displayed.

4.2.1 ALT 11ML Mode
Pressing the IML pushbutton while holding the AL T switch
in the'AL T 1 position bypasses the normallML test
sequences and causes the unit code to be loaded directly.
This will enable the user to bypass a failing test sequence
(for example, a defective Type B adapter). In this case, the
control unit is operational except for the Type B adapter.
The Bus and Lamp test functions the same as during a normallML. See Figure 4-2 for an ALT 1 IML sequence.

Code

Descripti on

0000

Control Logic failure - All four indicators not lit indicates
a control logic failure, The test sequence will not proceed. The failure of any adapter can also cause this failure. Parity problems can also appear to be control-logic
failures.

0110

Host Adapter Failure - A flashing display of this code
indicates the host adapter/attachment test failed.
Failure could be caused by the following, in addition
to defective cards: (1) range addressing does not agree
with customizing, (2) model specified wrong when
customized, (3) system diskette not for this machine,
or (4) problem on the host interface has disabled the
adapter.

0010

33FD failure - A flashing display of this code indicates
the 33FD disk drive failed. A steady display of this code
may be caused by any of the following:
1. Failure of the 33FD disk drive to come "ready."
2. A hung sequence (did not start) because of another
adapter failure. (See A2 board bypass procedure,
4.6.4.1
3. Loss of ground to the 33FD disk drive (check A 1Z2
cable).
4. Defective diskette.

0011

0100

0101

Type A Adapter failure - A flashing display of this code
indicates the test for this adapter not requiring a 3278
attached failed. A steady indication may indicate the
sequence is hung (did not start). Any activity from a
device that would normally disable the adapter will aiso
cause this test to fail.
Type A Adapter Failure - A flashing display of th'is code
indicates the tests for this adapter that require a 3278
attached failed. If a POR response was not detected
from port AO, this test will automatically be bypassed.
A failing display can also cause this test to fail.
Storage Card Failure - A flashing display of this code
indicates the storage test failed. The failure could be
caused by a defective storage card, failure of a component interfacing with storage (Extended Function Store
feature), or incorrect customizing parameters. If a 3278
display is powered on at port AO, additional failure information will be displayed on the screen.

Figure 4-1. IML Test Error Indications

Meaning

Step

Code

Meaning

1. ALT 1 and IML

1111

Bus and· Lamp test OK

1. ALT2and IML

1111

Bus and Lamp test OK

pressed

pressed
0000

Initiate Unit Code loading

2. ALT2and IML
released

0000

Begin Modem Wrap test

3. Wait

1111

Unit Code loading

3. Wait

0110

4. Begin normal
operation

0000

Unit Code loaded

Communication Adapter Test
running

0110

Flashing - Communication
Adapter Test failure

0111

Prewrap, Adapter Wrap, and
Modem Wrap tests are running

0111

Flashing - Modem Wrap test
has failed

1000

Successful test - Carrier not
present after completion of test

1111

Successful test - Carrier is present after completion of test

2. ALT 1 and IML
released

4. Wait

Figure 4-2. ALT 1 IML Sequence

Description

Low Storage failure - A steady display of this code in
the 842 1 Indicators indicates a failure in low storage.

Code

A hang condition at either step 3 or step 4 usually indicates a defective system diskette or a configuration error.

Code

0001

Step

0111

1000

4.2.2 AL T 2 1M L Mode, Model C with Wrappable
Modem (Test/Operate Switch in Operate
Position)
Pressing the IML pushbutton while holding the AL T switch
in the AL T 2 position invokes an extended Modem Wrap
test. Some types of modems require manual intervention
to set up for wrap testing. The test checks the transmission
path (Transmit and Receive Data lines) to and from the
modem. Modem clocking is required to run this test successfully, and a missing or defective modem clock will result in
a failure indication (flashing 0111). The intent of this test
is not to test the modem. The Bus and Lamp test functions
the same as during a normal IML. See Figure 4-3 for this
A LT 2 sequence.

Modem Wrap failure - A flashing display of this code
indicates the Modem Wrap/DDS Adapter test failed.
The wrap test is run only if a wrappable modem was
specified at customizing time. I f a 3278 is powered on
at port AO, additional information concerning the
failure is available on the screen. Data displayed is as
follows:
0111 016
- Modem failed to set Clear to Send
01-11 013
- General modem failure
Type B Adapter failure - A flashing display of this code
indicates the Type B Adapter test has failed. The test
looks for the first Type B display powered on and
attempts to do an Erase-Write-Erase operation. The
cursor is left in the lower right portion of the screen.
Any Type B device failure that would disable the adapter
would cause this test to fail.

1001

Encrypt/Decrypt Adapter Failure - A flashing display
of this code indicates that the Encrypt/Decrypt Adapter
test has failed.

1010

33FD Error - This flashing code is displayed whenever a
33FD problem has been detected after the initial 33FD
test. This failure can also be caused by invalid tracks or
data on the diskette.

Note: A t least one complete IML test sequence is required to
initialize control storage. Bypassing IML by using either AL T 1 or
AL T 2 mode does not perform this initialization function; it is
therefore possible that invalid parity may exist after initial power
on if normal IML has been bypassed.

4.2.3 AL T 2 IML Mode, Model C without Wrapable Modem (Test/Operate Switch in Test
Position)
Pressing the IML pusbhutton while holding the AL T switch
in the AL T 2 position invokes an extended Modem Wrap
test. When a nonwrappable modem is being used, the EIA
test cable Test/Operate switch should be in the TEST
position. This test checks the transmission path (Transmit
and Receive Data lines) to and from the Test/Operate
switch at the end of the cable. The test cable must be
attached to the modem, and the modem must provide
clocking or a failure indication of 0111 (flashing) will
result. The Bus and Lamp test functions the same as during
a normal IML. See Figure 4-4 for this AL T 2 sequence.
A normal IML is required to begin normal operation. When
this test is run in AL T 2 mode, there is no 3278 display
of failing indications (0111 013, etc.). See paragraphs
5.4.3 and 5.4.4 of the 3274 MIM, for additional information on the Wrap Test without Modem, and DDS Adapter
Wrap Test.

SY27 -2512-3

5. End Test - A
normal IML
required to
begin normal
operation

When this test is run in AL T 2 mode, the 3278 does not display the
84 2 1 indications.

Figure

4-3. AL T 2 IML Sequence, Model C with Wrappable Modem

Step

Code

Meaning

1. A L T 2 and 1M L

1111

Bus and Lamp test OK

2. AL T 2 and IML
released

0000

Begi n Modem Wrap test

3. Wait

0110

Communication Adapter Test
running

0110

Flashing - Communication
Adapter Test failure

0111

Prewrap, Adapter Wrap, and
Modem Wrap tests are running

0111

Flashing - Modem Wrap test has
failed

1000

Successful test

pressed

4. Wait

5. End Test

1000

Carrier not present

1111

Carrier is present

6. Return TEST/
OPERATE switch
to OPERATE
position.

Figure 4-4. ALT 2 IML Sequence, Model C without
Wrappable Modem

4·1

SY27-2512-3
4.2.4 AL T 2 1M L Mode, Model A Local Channel
Attachment
AlT 2 IMl Mode enables the 3274 interface to run Routine
1 of OlTs from the host CPU before the 3274 is customized.
To enter the Al T 2 IMl Mode, press the IMl pushbutton
while holding the AlT switch in the AlT 2 position. The
Bus and lamp test functions the same as during a normal
IML. See Figure 4-5 for the AlT 2 sequence.

.4.2.6 ALl2 IML Mode, Model D Local Host
Attachment
Al T 2 1M l Mode enables the 3274 interface to run
Routine 1 of 0 l Ts from the host CPU before the 3274
is customized. To enter the AlT 2 IMl Mode, press the
IMl pushbutton while holding the AlT switch in the
Al T 2 position. The Bus and lamp test functions the
same as during a normal IML. See Figure 4-7 for this
Al T 2 sequence.

4-2

Flashing
Indicator

Steady
Indicator

Operator Panel
Poor Indicator

1111

Off

111

On or flashing
On or flashing
On or flashing
On
On
On

000
111
100
010
001

Step

Code

Meaning

1. ALT2 and IML
pressed

1111

Bus and Lamp test OK

Step

Code

Meaning

1111

Bus and Lamp test OK

2. ALT2 and IML
released

0000

Start sequence

1. ALT 2 and IML
pressed

Start sequence

0010

Verifies this is a 3274 Model A

2. ALT2andlML
released

0000

3. Wait until code
appears

4. Turn Power/
Interface switch
to LOCAL/ONLINE

0100

3. Wait until code

0101

Verifies this is a 3274 Model D

Flashing
Indicator

0110

System interface is now enabled

1111

Off

1111

On or flashing
On or flashing
On or flashing
On
On
On
On

System interface is now enabled

~ppears

4. Turn Power!
Interface switch
to LOCAL/ONLINE

5. Routine 1 of OL Ts
can now be run
6. A normal IML is
required to return
to normal operations

Figure 4-5. Al T 2 IML Sequence, Model A Local Channel
Attachment

4.2.5 AL T 2 IML Mode, Model B Local Host
Attachment
Al T 2 1M l Mode enables the 3274 interface to run
Routine 1 of OlTs from the host CPU before the 3274
is customized. To enter the AlT 2 IMl Mode, press the
IMl pushbutton while holding the Al T switch in the
Al T 2 position. The Bus and Lamp test functions the
same as during a normal 1M L. See Figure 4-6 for this
( Al T 2 sequence.
Step

Code

Meaning

1. ALT 2 and IML

1111

Bus and Lamp test OK

pressed
2. ALT2and IML
released

0000

Start sequence

3. Wait until code
appears

0001

Verifies this is a 3274 Model 1B

4. Turn Power!
Interface switch
to LOCAL/ONLINE

0011

Syst,em interface is now enabled

5. Routine 1 of OL Ts
can now be ru n
6. A normal IML is
required to return
to normal operations

Figure 4-6. ALT 2 IML Sequence, Model B Local Host
Attachment

Figure 4-7. ALT 2 IML Sequence, Model D Local Host
Attachment

4.2.7 ALT 2 IML Mode, Modem Self-Test for
Model C with Greater than 1200-bps
Integrated Modem
Pressing and holding the Al T IMl Address switch in position 2 causes the modem self-test to be initiated and
repeated about every 4 seconds until the switch is released.
Releasing the switch should return the modem to Operate
mode, regardless of the test results.
While the test is being run, the TEST light on the operator
panel is lit. If the test is successful, the Data Quality-Good
indicator on the operator panel will flash each time the
test is run. The indicators on the A 1 D2 card will also flash
each time the test is run successfully.
If the test fails, the failing card is indicated in the A 1 D2
card indicators. Figures 4-8 through 4~ 10 show the meanings of the indicators. Cards indicated as failing are
replaced in order of probability. If multiple A 1 D2 card
indicators are displayed, replace all cards indicated.

Test successful
No failure
D2,G2,C4
D2,G2,C4
D2, G2, C4
C2,G2,D2
G2,D2
D2, G2, C4

1 = On
0= Off

Figure 4-8. A 102 Card Indicator for 2400-bps Integrated
Modem.
Steady
Indicator

0000
1111
1000
0100
0010
0001

5. Routine 1 of OLTs
can now be run
6. A normallML is
required to return
to normal operations

4.3
Failing Card

Operator Panel
Poor Indicator

Failing Card
Test successful
No failure
D2,G2,F2,C4
D2,G2,C4
D2,F2,G2,C4
C2,G2,D2
F2,D2,G2
G2,F2,D2
D2,F2,G2,C4

Figure 4-9. A 102 Card Indicator for 4BOO-bps Integrated
Modem.
Steady
Indicator

Operator Panel
Poor Indicator

1111

Off

1111

On or flashing

0000
1111

On or flashing
On or flashing

1000
0100
0010
0001
0000

On
On
On
On
On

4.3.1 Purpose
This Ol T provides testing for the 3274 Model A display
system local channel attachment and supplements the
testing that is performed during the IMl sequence of the
3274 Model A. For additional information, see OL Ts
User's Guide, D99-3274D.
Prior to invocation of the OlT, the 3274 must complete
its IMl sequence; that is, the 3274 operational resident code
is in control and ready for I/O operations with the host.

4.3.2 Applicable Executive Control Programs

1 = On
1 = Off

Flashing
Indicator

LOCAL MODEL A DISPLAY SYSTEM
ONLINE TESTS (T3274B)

Failing Card
Test successful
No failure
E2, G2, F2,
D2,C4
E2, G2, C2, C4
E2, 02, F2,
G2,C4
D2,F2,E2
F2, 02, E2,G2
G2,E2,F2,D2
E2,F2,G2,D2
C2,G3,E2,02

1 = On
0= Off

Figure 4-10. A 102 Card Indicator for 9600-bps
Integrated Modem.

These Ol Ts are compatible with the following control programs at the levels indicated or higher:
DOS/VS Ol TEP
OS/VS1 Ol TEP
OS/VS2 SVS Ol TEP
OS/VS2 MVS OlTEP
TeAM TOTE
OlTSEP
OS OlTEP
DOS OlTEP

33
6
1.7
3.7
10
9.0
21.8
26

•

4.3.3 Composite Error Message Description

4.3.4 OL T Routines

4.3.5 CDS Card Format, Model A

Figure 4-11 shows an example of a maximum configuration
of error message content, with an explanation of each item_

Figure 4-12 lists the T32748 online test routines. Included
are the Kingston control number, the module i~entification,
the routine numbers, and the titles.

Figure 4-13 shows the COS card format for the local 3274
Model A display system online tests.

Content

KNo.

Module 10

K685

X3274AA

13
14
15
16

T3274B - vl RTN nn DEV/LN ccuu ECAec REFNUN yyzzz
PLINK 10 = X3274ss-vl
Test and failure description (can be a total of 8 lines)
CCWOl command address flags count CAW address
CCWnn command address flags count
XPTD CSWl XX last ccwaddr+8 status count
RCVD CSWl XO last ccwaddr+8 status count
XPTO CSW2 XX last ccwaddr+8 status count
RCVD CSW2 XO last ccwaddr+8 status count
XPTO CC condition code RCVD CC condition code
XPTO SNS sense data
RCVD SNS sense data
XPTO DATA expected data
RCVO DATA received data
WRTN DATA write data
Test messages (can be up to 9 lines)

Item

Explanation

Item
1
2
3
4
5
6
7
8
9
10
11

Routine Number
Decimal Hex
01

Equivalent
CDS Byte

Content

Title

Leave blank

Test No Op Control
Command

K686

X3274AB

Test Sense 10 Command

K687

X3274AC

Test Vary Activate
Sequence

K688

X3274AO

Test Vary Deactivate
Sequence

Figure 4-12. T3274B OL T Routines

2-4

CDS

5-9

Leave blank

10-17

0-3

Channel, control unit
device address

18-21

4-5

Leave blank

22-23

40 = class code

24-25

F2 = type code

26-35

8-11

Leave blank
Slash U) - End of CDS

Figure 4-13. CDS Card Format, Model A

4.4 LOCAL MODELS BAND 0 DISPLAY
SYSTEM ONLINE

This is the standard header line provided by OL T(s) EP:

Card
Column

T3274B
v1
nn
ccuu
ec
yyzzz

lOaf 3274 Model A OLT root module
Version and level of root module
Decimal value of routine number
Address of 3274 Model A control unit
FE announcement letter number describing a required change
Hexadecimal equivalent of routine number and error 10 within that routine

X3274ss
v1

10 of active test module during error

4.4.1

Purpose

This OL T provides testing for the 3274 Models 8 and 0
display system local host attachment. This 0 LT supplements the testing that is performed during the IML sequence.
For additional information, see OL Ts User's Guide,
099-3274A.

Version and level of test module

Note: A PLINK 10 of XXXXXXXXXX means no plink module was active when the error occurred.

These lines provide the name of the test and the failure description. These I ines are printed in all error messages.

4-5

These lines define the CCWs and CAW which were issued at the time of error. These lines are printed in all error messages.

6-7

These lines contain the hexadecimal data for the expected and received CSWs. These lines are printed in all error messages except for
timeout of the I/O event.

8-9

These lines contain the hexadecimal data for the expected and received CSWs for the second interrupt (if there is one). These lines
are printed only when the expected and received CSWs are not equal to zeros.

The expected and received condition codes. This line is printed only when the expected and received CCs are not equal.

11-12

13-14

Prior to invocation of the OL T, the 3274 must complete
its IML sequence; that is, the 3274 operational resident code
is in control and ready for I/O operations with the host.

4.4.2 Applicable Executive Control Programs
These OL Ts are compatible with the following control programs at the levels indicated or higher:

These I ines contain the hexadecimal data for the expected and received sense data (if any). These I ines are printed only when the
expected and received SNSs are not equal. The sense bits are defined below.
B~eO

By~l

Bit 0 command reject
1 intervention requ ired
2 bus out check
3 equipment check
4 data check
5 overrun (bit not used)
6 not initialized
7 this bit is not assigned

Bit 0
1
2
3
4
5
6
7

DOS/VS OL TEP
OS/VS10LTEP
OS/VS2 SVS OLTEP
OS/VS2 MVS OLTEP
TeAM TOTE
VTAM TOLTEP
OLTSEP
OS OLTEP
DOSOLTEP

data length check
data reject
this bit is not assigned
th is bit is not assigned
parity check modifier
parity check number 1
parity check number 2
cycle steal machine check

Lines 13 and 14 contain the hexadecimal data for the expected and received data (if any). These lines are printed in all error messages
where the failing routine executed a read type command.
The hexadecimal write data (if any). These lines are printed in all error messages where the failing routine executed a write type command.

These lines may be used to provide additional messages for the error printout.

33
6
1.7
3.7
10
2.0
9.0
21.8
26

Figure 4-11. Example of Maximum Configuration of Error Message Content, Model A

SY27-2S12-3

4-3

SY27 -2512-3

4-4

4.4.3 Composite Error Message Description

4.4.4 0 LT Routines

Figure 4-14 shows an example of a maximum configuration
of error message content, with an explanation of each item.

Figure 4-15 lists the T3274A online test routines. Included
are the Kingston control number, the module identification,
the routine numbers, and the titles.

Content

Item
'V

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Item

T3274A -v1 RTN nn DEV/LN ccuu ECAec REFNUM yyzzz
PLINK ID = U3274ss-v1
Test and failure description (can be a total of 8 lines)
CCW01 command address flags count CAW address
CCWnn command address flags count
XPTD CSW1 XX last ccwaddr+8 status count
RCVD CSW~ XO last ccwaddr+8 status count
XPTD CSW2 X-X last ccwaddr+8 status count
RCVD CSW2 XO last ccwaddr+8 status count
XPTD CC condition code RCVD CC condition code
XPTD SNS sense data
RCVD SNS sense data
XPTD DATA expected data
RCVD DATA received data
WRTN DATA write data
Test messages (can be up to 9 lines)

K No.

Routine
Module 10 Decimal

K661

U3274AA

K662

U3274AB

K663

U3274AC

Number
Hex

Title

U3274ss
v1

ID of active test module during error
Version and level of test module

Note: A PLINK ID of XXXXXXXXXX means no plink was active when the errror occurred (e.g., error during cleanup).
3
4-5
6-7
8-9
10
11-12

Test Valid Commands
for Acceptance

Test I nvalid Commands
and Sense Command
Operation

4.5.2

These OL Ts are compatible with the following control
programs at the levels indicated or higher:

K665

U3274AE

Test Sense I D
Command

K668

U3274AH

Test Chained
Commands

K671

U3274AK

Test Unchained
Commands

K674

U3274AN

Test Write Command
with a Set Buffer
Address Order to an
Invalid Address

Figure 4-16 shows the CDS card format for the local 3274
Models Band D display system online tests.
Card
Column

Equivalent
CDS Byte

DOS/VS 0 LTEP
OS/VS1 OL TEP
OS/VS2 SVS OlTEP
OS/VS2 MVS OLTEP
TCAM TOTE
OLTSEP
OS OLTEP
DOSOLTEP

33
6
1.7
3.7
10
9.0
21.8
26

CDS
Leave blank
0-3

These lines contain the hexadecimal data for the expected and received CSWs for the second interrupt (if there is one), These lines
are printed only when the expected and received CSWs are not equal to zeros.

18-19

Blank or 00 = Model B
80 = Model D

20-21

Must be 00

22-23·

6
7

26-35

8-11

The hexadecimal write data (if any), These lines are printed in all error messages where the failing routine executed a write type
command.

These lines may be used to provide additional messages for the error printout.

OLT

3274 Model C BSC operating
with a 270X, or a 370X with
the Emulator Program (EP).

D99-3274B

R3274A

3274 Model C BSC
operating with a 270X, 370X
EP, or a 370X NCP. R3274B
requires that the 3700 Series
Diagnostics be cataloged at
the host. I t is suggested that
R3274A be used when
operating with a 270X , or
370X EP .

D99-3274-C
D99-3700A

R3274B

D99-3700C
D99-3705A

T3700LTE
T3705

Leave blank
2-4

24-25

OLT User's
Guide

Configuration

5-9

The expected and received condition codes. This line is printed only when the expected and received CCs are not equal.

See Figure 4-17 to determine the OL T to be used for a
specific configuration.

Content

10-17

Channel, control unit
device address

=class code
. 10 = type code
10

Leave blank
Slash (I) - End of CDS

Figure 4·16. COS Card Format, Models Band 0

3274 Model C SDLC operating
with a 370X NCP. Use the
following Link Level Tests:
Link Level 1
Link Level 0

Figure 4-17. 3274 Model C Online Tests

Figure 4-14. Example of Maximum Configuration of Error Message Content, Model B

•

Applicable Executive Control Programs

4.5.3 Model C Online Tests
4.4.5 CDS Card Format, Models Band 0

These lines contain the hexadecimal data for the expected and received data (if any). These lines are printed in all error messages
where the failing routine executed a read type command.

13-14

Prior to invocation of the OL T, the 3274 must complete
its IML sequence; that is, the 3274 operational resident code
is in control and ready for I/O operations with the host.

Figure 4-15. T3274A OL T Routines

These lines contain the hexadecimal data for the expected and received CSWs. These lines are printed in all error messages except
for timeout of I/O event.

These lines contain the hexadecimal data for the expected and received sense data (if any). These lines are printed only when the
expected and received SNSs are not equal.

These OL Ts provide path testing for the 3274 Model C
display system host attachment downline from a 270X
or a 370X.

These lines provide the name of the test and the failure description. These lines are printed in all error messages.
These lines define the CCWs and CAW which were issued at the time of error. These lines are printed in all error messages.

Purpose

Test No Op Control
Command

Explanation

10 of 3274 Model B OLT root module
Version and level of root module
Decimal value of routine number
Address of test terminal
FE announcement letter number describing a required change
Hexadecimal equivalent of routine number and error 10 within that routine

4.5.1

This is the standard header line provided by OL T(s) EP:
T3274A
v1
nn
ccuu
ec
yyzzz

4.5 MODEL C DISPLAY SYSTEM ONLINE
TESTS

4.6 SERVICEABILITY AIDS

4.6.3 Isolate Feature Board 01A·A2

The following procedures are intended to supplement problem determination and troubleshooting techniques. Monitoring procedures for interface lines, coax checking procedures, and patching procedures are some of the aids
provided.

It may be desired at times to isolate the A2 feature board
during troubleshooting and continue to run IML. Use the
following procedure to isolate the board:

4.6.1

Monitoring of EIA Interface Lines
(Model C)

The EIA interface lines and associated scoping points for
the Model C are identified as follows:

EIA Interface Lines
Al02S04
Al02S10
Al02S12
A 102S13
Al02U04
Al02Ul0
A 102Ul1
Al02U12
Al02U13

Carrier Detect
Req to Send
Clr to Send
Data Set Rdy
Transmit Data
Receive Clock
Transmit Clock
Data Trmnl Rdy
Receive Data

4.6.2

Monitoring of Bus/Tag Interface Lines
(Models A, B, and D)

The EIA interface lines and associated scoping points
for the Models A, B, and 0 are identified as follows:
Bus Interface lines
Bus Out Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit

0
1
2
3
4
5
6
7
p

Al N2U12
A 1 N2S12
A 1 N2U13
A1N2U06
A1N2S07
A1N2U07
A1N2S08
A1N2U05
A1N2S05

1. Power off.
2. Remove board crossover cables at 01 A-A 1Y5 and A 1Y6.
3. Lower the logic gate, and raise the secondary power
supply.
4. Use an SL T jumper wi re to connect A 1 R 1 B11 to
A1R1El1.
5. Troubleshooting can now continue with the A2 board
isolated. (IML will fail with a flashing 1000 with the A2
board removed from logic.)
6. Remove the jumper, and replace the crossover cables
when the problem has been resolved.

3. Replace the system diskette with the feature diskette
used in step 1. Do not press 1M L. Within 1 minute, the
842 1 indicator code will be a steady 0001. If you are
using a 3279, the color convergence pattern will be displayed on the display screen. To bypass this pattern,
hold down the AL T key, press and release the TEST
key, and release the AL T key. Sequence number 001
will be displayed on the display screen. Continue with
step 4.

•

Use the steps listed below to perform the diskette
patching procedure. If, while performing steps 4 and 5,
you want to cancel what you have done and start again,
enter FF and press the ENTER key. This will bring you
back to step 3. If you enter an unacceptable response, the
operator code in the upper center of the display will alert
you to the problem. Figure 4-18 gives the meanings of the
operator codes.
The 8 4 2 1 codes also provide a guide to your progress in
the patching procedure.

A1N2G12
A1N2G13
A 1 N2J13
A1N2M08
A1N2M09
A1N2P09
A lN2Pl0

1. Insert the feature diskette. While holding the Alt IML
Address switch in position 1, press and release the IML
button; then release the Alt 1M L Address switch.
Within 2 minutes, the 8 42 1 indicator code will be
flashing 1011.
2. Replace the feature diskette with the customized system diskette. Do not press IML. Within 1 minute, the
842 1 indicator code will be flashing 1110.

•

Press the spacebar once.

•

Key in the two-digit Validation Number shown on
the system diskette label.

•

Press ENTER.

5. When sequence number all appears, enter 1 and press
ENTER.
6. When sequence number 012 appears, enter the patch
header information, and press ENTER.
7. When sequence number 013 appears, enter the patch
information one line at a time. Press ENTER after
each line. After all lines of the patch have been
entered, enter 49 and press ENTER.
8. Sequence number all will appear again. If you have
another patch to enter, enter 1, press ENTE R, and
go to step 7.

1011 -

Replace the feature diskette with the system
diskette. Do not press IML. Within 20 minutes, the indicator code will change to 1111.
The patch procedure is now complete, and a
normal startup can be initiated.

1101 -

Replace the feature diskette with the language
diskette. Do not press IML. Within 30 seconds, the indicator code wil Lchange to 0111
and then to flashing 1011 within 1 minute.
When the indicator code is flashing lOll,
replace the language diskette with the system
diskette. Do not press IML. Within 20 minutes, the indicator code will change to 1111.
The patch procedure is now complete and a
normal startup can be initiated.

If you do not have another patch to enter, enter 0,
press ENTER, and go to step 9.
9. At this time, either sequence number 021 is displayed
(meaning that no printer authorization matrix has been
defined), or the defined matrix is displayed.
If sequence number 021 is displayed, key in a and
. press ENTER.

Tag Interface lines
Hold Out
Suppress Out
Op Out
Service Out
Address Out
Command Out
Select Out

Replace the feature diskette with the RPO
diskette. Do not press IML. After the RPO
diskette is inserted, the code will change to
0111 within 30 seconds. If additional RPQ
diskettes are required, the indicator code will
again flash 1100. Repeat the procedure for
each additional RPO diskette. Do not press
IML. When the RPQ diskette procedure is
completed, the indicator code will be flashing
1110. Reinsert the feature diskette. Do not
press IML. Within 2 minutes, the 8 4 2 1 indicator code will flash 1011 or 1101.

Key in the following characters:
1234567890ABCD E F

This procedure is to be used by the support customer
engineer, at the direction of the next level of the support
structure.

Before the patching procedure can be performed, the
patch header information and the patch coding must be
obtained from the next level of the support structure.

1100 -

If you want to converge the 3279, follow the instructions in the "Color Convergence Procedure" in the IBM
3270 Information Display System 3274 Control Unit
Planning, Setup and Customizing Guide, GA27-2827.
4. When sequence number 001 appears in the upper-left
corner of the display screen:

4.6.4 Diskette Patching Procedure

Note: Diskette patching is an emergency procedure only.
It should be used only when time will not permit waiting
for an update diskette from the Raleigh distribution center.

11. When sequence number 999 appears, move the cursor
to the entry for 900, change it to a 1, and press
ENTER.
12. Within 2 minutes, the 842 1 indicator code on the
3274 Control Unit will be flashing one of the following:

If a matrix is displayed, move the cursor to the entry
for 901, change it to a 1, and press ENTER.
10. When sequence number 031 appears, enter the number
of RPQ diskettes being used (0, 1,2; or 3), and press
ENTER.

SY27 -2512-3

4-5

SY27-2512-3
Code

Meaning
One or more of the fi rst 10 characters is incorrect;
reenter response.

One or more of the 11th to 17th characters, including
the space, is incorrect; reenter response.

The diskette level is wrong; use the correct diskette.

An invalid response has been entered (too many characters, value too high or too low, wrong character,
reenter respohse.

An entry other than A, B, or C was entered in response
to sequence 151; reenter response.

The response has too few characters; reenter response.

The numerical sum of the responses to sequence numbers 111 and 112 is greater than 32; verify, and reenter
responses(s) .

An unacceptable change was made during modification
(sequence 999); recheck entries, and correct.

If the response to sequence number 321 is 1, the
responses to sequence numbers 121 and 131 must be 02
and 1, respectively.

4.6.5 Dump Procedure
The 3274 Dump Diskette is to be used when the System
Support Center requests a 3274 subsystem dump. The 3274
Subsystem Dump Procedure should be performed by the
customer engineer, but, for intermittent problems, it can be
performed by the customer.
1. For a 3274 Model A, B, or 0, set the Power/Interface
rotary switch to the Local/Offline position and check
to see that the Local/Offline indicator is on. If the indicator fails to come on, momentarily ground the appropriate pins as indicated in the following list to force this
condition:

Invalid characters were entered; reenter response.

All patch areas are in use.

The patch I D number (header) already exists; use a new
header.

The update number does not match the number in the
configuration table; verify, and reenter response.

An attempt was made to delete a patch that does not
exist.

The call line did not contain the correct data length.

Patch information was not entered. Sequence number
013 must have at least one patch before 48 is entered.

The number of lines entered does not agree with the
count specified in the header line.

All entries are acceptable, but the entry for sequence
number 900 has not been changed to 1.

A
B

01A1-P2D10
01A1-02B07
01A 1-02G05

After the dump proced).lre has been completed, place the
dump diskette between protective sheets of cardboard.
Insert the diskette and your return label with your return
address and other pertinent data into the return envelope.
Send the complete package to the requesting System
Support Center.
Note: If, at any time during the execution of this procedure, the 842 1indicator lights display a steady 1100
code, an unrecoverable diskette drive error has occurred.
If this condition occurs, retry the procedure, starting at
step 1.

The 1100 error code will also appear if you are trying to
perform a dump when no data exists in the 3274 storage.
This could occur when you attempt a dump immediately
after turning on the 3.274 (prior to the initiaIIML).

4.6.6 Backup System Diskette Generation
Note: The customer does not have direct access to
these pins. If the CE expects the customer to encounter
this condition, he must temporarily install a special
grounding switch (PN 5718026) into the customer
access area. For a 3274 Model C, this step is not
applicable: go directly to step 2,

One or more responses are not compatible with the
response to sequence number 331; verify, and correct
response(s) .
The responses to sequence numbers 131, 132, and 133
are O's (at least one must be a 1); verify, and correct
response(s) .

Pin Number

If the response to sequence number 321 is 0, the
response to sequence number 121 must not be 02.
23

3274 Model

4-6

2. Replace the system diskette with the dump diskette.

See the 3274 Control Unit: Planning, Setup, and Customizing Guide, GA27 -2827, for detai Is.

4. After a few minutes of operation, the 84 2 1 indicator
lights will change to a flashing 1011 code. When this
condition occurs, replace the dump diskette with the
system diskette. Do not press IML.
5. After the system diskette is inserted, the 842 1 indicator lights will first change to a steady 0000 code
and, after approximately 10 seconds, to a flashing 1001
code. When this condition occurs, replace the system
diskette with the dump diskette. Do not press 1M L.
6. When the 842 1 indicator lights change to a steady
1111 code, the dump procedure is completed. When
this condition occurs, replace the dump diskette with
the system diskette and perform a normal IML to
restore the subsystem for customer operation.

Figure 4-18. Operator Codes
Note: Follow this procedure exactly, using only the dump
diskette and the system diskette at the specified steps. If
the wrong diskette was used, retry the procedure, starting
at step 1.

Cable 1 is a RG62A/U modified for outdoor/underground
installation. This cable is suitable for indoor and outdoor
installation and for direct burial. Cable may be purchased
from IBM or from a source selected by the customer.
Bulk cable may be ordered from IBM by specifying IBM
PN 5252750 and the length on a miscellaneous equipment
specification (MES) form. Preassembled cables may be
purchased from I BM by specifying IBM PN 1833108 and
the length on the MES form.
For fabricating cables, two BNC-type connectors are
needed, IBM PN 1836447 or equivalent outdoor type.
These two connectors may be obtained in a kit from IBM
by specifying "Connector G~oup (outdoor type); IBM PN
1836419" on the MES form. Instructions for assembling
BNC-type connectors on bulk cable are given in Assembly
of Coaxial Cable and Accessories for A ttachment to IBM
Products, GA27-2805.

4.6.8.3 Coax Cable Splicing
4.6.7

Display Customizing Responses

These cables must be procured, installed and maintained by
the customer. Cable h is for indoor installation only; cable
1 is for outdoor installation, although it is approved for
indoor use as well.

Do not cut and splice cables; instead, use a quickdisconnect adapter, IBM PN 5252643, or commerical
adapter, Amphenol Corp. part UG-914/U. A maximum of
13 connections is allowed in any given cable run. The
adapter and the attached cable connectors must be covered
with 127 mm (5 inches) of shrink tubing, 19,05 mm (0.75
inches) expanded diameter, to prevent accidental grounding
of splice. This adapter and connecting jacks should be
waterproofed forapplications requiring this type of
installation.

4.6.8.1 Cable h (I ndoor)

4.6.9 Coax Testing with Scope

Presently, the only approved cable bears the commerical
designation RG62A/U. Cables may be purchased from IBM
or from a customer-selected source. Bulk cables may be
ordered from IBM by specifying IBM PN 323921 and the
length on a miscellaneous equipment specification (MES)
form. Preassembled cables may be purchased from IBM by
specifying IBM PN 2577672 and the length on the MES
form.

This procedure describes how to test any length of coax
cable-in segments of up to 1500 m (5,000 ft)- with a
Tektronix 453 oscilloscope, or equivalent. For additional
information on coax testing, refer to the Oscilloscope
Measurement Procedure for Twisted and Coax Cables,
S226-3913.

See the 3274 Control Unit: Planning, Setup, and Customizing Guide, GA27-2827, for details.

3. While holding the Alt 1M L Address switch in position 1,
momentarily press and release the IML switch; then
release the Alt 1M L Address switch.

4.6.8.2 Cable 1 (Outdoor)

4.6.8 Coax Cables (h and 1)

For fabricating cables, two BNC-type connectors are
needed: IBM PN 1836444 or equivalent. These two connectors can be ordered in a kit from I BM by specifying
"Connector Group (indoor type), IBM PN 1836418" on
the MES form. Instructions for assembling BNC-type
connectors on bulk cable are given in Assembly of Coaxial
Cable and Accessories for Attachment to IBM Products,
GA27-2805.

Note: Since the communication lines are the customer's
responsibility, the following practice should be observed:
•

Use this procedure only after (1) all product maintenance procedures have been followed, (2) a communication line problem is suspected, and (3) the customer
indicates he cannot locate the line problem.

•

Do not use the procedure for the express purpose of
checking the quality of the wiring work done by customer personnel or by a contractor.

4.6.9.1 Testing for Discontinuities

The reflected wave is delayed by the time it takes for the
incident wave to travel to and return from the termination.
The delay is called propagation delay and is expressed as
a percentage of the speed electronic waves travel in a specific
type of cable (usually 60-80%) as compared with the speed
that they travel in open air-the speed of light (100%).

This test consists of looking for impedances attached to the
communication Iine that are different from the characteristic impedance of the line, Zo (93 ohms). This is done by
sending a wave front (leading edge of square wave) down
the line and looking for energy that is reflected by any
p,!int that differs from the characteristic impedance.

If the propagation delay of the cable is known, the scope
can be calibrated to meters or feet per division, and the
distance to a mismatch-shorts, opens, etc.-in the cable can
thus be determined:

The "B" gate" out pulse is the square wave that is applied
to the coax line; it travels down the line at about 80% of
the speed of Iight, depending upon the isolation material
used in the cable. If no impedance impairment is present
on the line, the wave front travels down the line until the
termination is reached, and all the energy contained in the
wave front is absorbed in the termination.

The speed of light is 300,000 km/sec, or 30 cm/nanosec,
or 0.984 ft/nanosec. Propagation delay in a coax cable is
about 1.25 ns/ft. The DC resistance is 44 ohms/1000 ft.

,,-- - - R =

> Zool?en

• Shorter than 20 m (60 ft)-use the Xl0 time base.
This distance represents only about two horizontal
divisions to the center of the screen. Switch to Xl 0
magnifier. B time can now be set to .2 or .5, and
speed can be considered 0.02 and 0.05.

4.6.9.2.1 Parts:

X1 probe (or short piece of coax with
BNC connector on each end).
1 resistor equal to Zo of cable (93 ohms)
1 BNC T (PN 1650789)
1 probe-tip-to-BNC adapter (PN 453199) (not needed
if short coax is used as input from T-connector to scope
input)

4.6.9.2.2 Scope Hookup:

2. Use the following conversion table to determi ne
distances.
8-sweep setting {J.lsecl

0.1
0.2
0.5
1.0
2.0

Make the connections

shown in Figure 4-20.

4.6.9.2.3 Initial Scope Settings:
Mode:
Volt/div:
Input:
A triggering level:
A sweep length:
Horiz. display:
B sweep mode:
A sweep mode:
Delay time multiplier dial:
A and B time division initial

Zo of the cables and the termination can vary, however,
in which case. not all the energy contained in the wavefront
is absorbed. The energy not 'absorbed is reflected back
toward the sending end. Viewing the sending end with the
oscilloscope allows display of both the transmitted wave
(incident wave) and the reflected wave. Figure 4-19 shows
examples of possible reflections for different terminations.
(

4.6.9.2 Setup and Test Procedures

chl
0.2 V (initial)
AC
fully counterclockwise
full
delayed sweep B
B starts after delay time
auto trigger
fully clockwise (9.5)
setting:

I
,-------~--------------------------I----------- R=930hms

4.6.9.2.4 Test Procedures

I I

1. Consider the cable length:

I I
I I
I '\
I -- -

Incident
Wave

= < Zo short

I
I

Up to 100 m (300 ft)-use the initial scope setup.

•

Up to 1500 m (5000 ft)-use B time division up to
2.0 psec.

•

Longer than 1500 m (5000 ft)-measure in segments
not exceeding 1500 m.

40
80
200
400
800

•

Measure from the point where the reflected pulse
starts to change (Figure 4-21). (R ise time degrades
with cable-length increase.)

•

Lower the volts/div, and use Vertical Position knob to
position waveform.

•

Identify the end of a cable by opening and shorting
the cable end.

•

After finding mismatches, measure as closely as possible to the fault. Measuring from both ends of the
cable enhances fault location; because of cable loss,
major faults at long distances can appear as minor
faults close to the test point.

Reflected Wave

I
I
I

•

(Feet!Div)

12.2
24.4
61
122
244

3. Use the following measurement techniques and become
familiar with Figure 4-22 to gain understanding of what
you may see displayed:

A: 10 psec
B: 0.1 psec (pull to unlock)

I
I

(Meter/Div)

Distance
I
1~"4r------------------------------~"~1

Reflected
Coax Open

Figure 4-19. Incident and Reflected Waves

Coax Cable

453 Scope

T·Connector
on 8-gate

(Segment or segment links, 1500 m (500 ft) max.)

(93 ohms)

Time = Distance

Coax disconnected
from Terminal and
Control Unit
X 1 Probe or Short
Coax Cable with BNC
Connectors on Each End

Measurement Point

Figure 4-21. Measurement Points
Figure 4-20. Scope Setup

SY27 -2512-3

4-7

SY27 -2512-3
Example A

This is an illustration of a good, no-fault coax
cable that is 190 m (624 ft.) long. A gradual
sloping and overshoot of rise time is normal.

--I-

0.5V
I-- A; 20 Ms
B; 0.2 Ms

4-8

Example 0

0.2~
I - A; 20 Ms

B; 0.2 Ms

Impedance Zo Checking

.-If'

This 93-ohm cable is terminated at the end with
a 93-ohm resistor. The straight line after 7.8
divisions shows that the characteristic
impedance of this cable is close to 93 ohms.

1.3

~ ....

Same as Example C, now with higher vertical
gain (0.2V!div).
Arrow points to start. Note the two wrinkles at
1.3 and 2.5 divisions from start; they represent
very small mismatches from BNC connection,
at 32 and 61 m (104 and 200 ft) from start.

2.5

+.-- ~

......

A reflection deviation of greater than 10% of
the incident wave usually indicates an undesirable impedance change and should be
corrected.

V'"

ff-

L.....J

Coax terminated
with 93-ohm resistor

Example B

Shorted
at end

Example E
101 m (332 ft) of good coax cable, 8.3 divisions
long. (This is an effective method to measure
the length of the cable.)

I
0.2V
I-- A; 20 Ms

·8; 0.1 Ms

8.3 x 40 = 332 ft or
8.3 x 12.2 = 101 m

I
0.5V
.... A; 10 Ms
B; 1 JlS

R isi ng slope is normal.

8.3~

r
-t

ttttt-

,
~

Total cable length 6 x 400 = 2400 ft

Fault point 1 x 400 = 400 ft

~V
~

This 2400-ft cable has a 100-ohm short to
shield at the 400-ft point (see arrow) .

~
~

ft-

Coax open-ended

Open·ended

Example F

Example C
The same cable as Example A now shorted at
end to show downward reflection and length.

0.2V
I - - A; 20 Ms

Length of sweep is 7.8 divisions (see arrows).

8; 0.2 Ms

8 setting

= 0.2 Msec or 80

7.8 x 80

= 190 m

Improper setup of scope.

0.5V
I - A; 20 Ms
B; 0.1 p,s

ft/div

(624 ft)

7.8

I"r

.....

, I

)

~ """"

Shorted
at end

1\0

Figure 4-22 (Part 1 of 2). Display Examples
1

Only the first reflection is significant and should be
magnified.
See Example G.

I mproper scope display due to wrong vertical gain
setting, .5V /div.

, ... -+}

... I~

MUltiple reflections, 30.5m (100 ft) of good cable
with open end.

Multiple reflections
of open-ended

Example G

Same as Example F, now with scope set to
higher vertical gain, 0.2V.

0.2V
-A; 20}1s
B; 0.1 }1s

r. ~ - j,

Open-ended
I

Example H
Same as Example G, but magnified with X10 .
.2)
20}1s
B; .5J,.ls~X1O

I-- A;

I'·

This is the first reflection section of
Example G.

-~ ~

A smooth cable 5.2 division long (as opposed
to 2.6 div on Example A) with overshoot.

5.2 x 20

= 104 ft.

Open-ended

Example J

r-----

I
"
,

......

I mproper setup of scope

0.2V

-100ft.
Shorted

A; 20 J,.ls
B; 2.0 J,.ls

Multiple reflections due to wrong, slow B group
setting.

j'\
Lr\
If \ j \, I
II ~ If
~\ l
r

Same 30.5 m (100 ftl as in Examples F, G and H.
Only the first reflection is significant; the normal, multiple reflections of the test pulse
should be cancelled out on the display by using
a B time that will display the first reflection
only, using the whole screen or as great a portion of the screen as possible. See Example H.

Multiple Reflections
coax shorted at end

Figure 4-22 (Part 2 of 2). Display Examples

.
~

SY27 -2512-3

4-9

Chapter 5. Reference Data
5.1 INTRODUCTION

5.2.2 EraseIWrite

This chapter provides the following information as an aid
to maintenance:
Command summary
Order summary
Various codes
Sequence/response diagrams
Status and sense byte descriptions
Switches and controls

MDT bit has been set. The data stream for each modified field contains the SBA order, the buffer address of
the attribute character plus 1, and all alphameric characters (with nulls suppressed).
3. The command is issued by the program or as a result of
an ENTE R, PF key, selector-pen attention, or operator
identification card read-in operation.

The Erase/Write command:
1.
2.
3.
4.

Clears the CU buffer to nulls.
Performs operations specified by the WCC.
Stores new data characters provided by the program.
Allows execution of various order sequences within the
data stream.
5. Transfers the updated CU buffer to the device buffer.

5.2.6.2 Short Read Read
1. The Short Read Read command permits the display
operator to communicate with the host program without
sending modified data characters. This action is initiated
when the display operator presses CLEAR, CANCEL, or
a PA key.
2. A read-modified operation is performed, but only the
unique AID character, to identify the key pressed, is
sent to the host program.

5.2.3 Erase/Write Alternate
The Erase/Write Alternate command:

5.2 CONTROL UNIT COMMAND SUMMARY

1. Switches the device to alternate character capacity.
2. Performs normal erase/write operation.

See Figure 5-1 for control unit command codes.

5.2.4 Erase All Unprotected
3274
Band D
EBCDIC
(Hex)

Command

3274C
EBCDIC
(Hex)

Graphic

COpyl

Erase All Unprotected

Erase/Write

5
=

Read Buffer

Read Modified

Erase/Write Alternate

The Erase All Unprotected command:

1. Clears all unprotected alphameric characters to nulls,
resets modified data tag (MDT) bits of all unprotected
fields to 0, restores the keyboard, resets the attention
identifier (A ID), and repositions the cu rsor to the fi rst
character location in the first unprotected field in the
buffer.
2. Is performed at the device and has no data stream.

5.2.6.3 Test Request Read [Models S, e (SSe),
and DJ

5.2.5 Read Buffer

Write

No Operation

Select

Sense

1. The Read Buffer command transfers the contents of the
addressed device buffer to the CU buffer.
2. Data stream transferred to the host includes the AID
character, the cursor address, and the contents of all
device buffer locations (both protected and unprotected). These include attribute and alphameric characters (including nUlls), starting at a specific location
and continuing to the end of the buffer, unless the
channel byte count goes to zero before the last location is reached.

Read Modified AII

1 Applicable to 3271 and to 3274 Model C (BSC).

2 Applicable to 3274.

3 Applicable to 3274 Models A and C (SNA/SDLC).

Figure 5-1. Command Codes

5.2.1 Write
The Write Command:
1. Transfers the contents of the addressed device buffer to
the control unit (CU) storage buffer.
2. Performs the operation specified by the write control
character (WCC).
3. Enters data in any portion of the CU storage buffer
(without erasing or modifying portions of the buffer in
which a change is not required).
4. Allows execution of various order sequences within the
data stream.
5. Transfers the updated CU buffer to the device buffer.

5.2.6 Read Modified
Receipt of a Read Modified command (or a Poll when an
AlDis pending) generates one of three data streams,
depending on the AID code present. Their descriptions
follow.

1. A read-modified operation is performed if the TEST
REO or the SYS REQ (BSC only) key has been pressed
at a device.
2. A Test Request Read heading is generated by the control
unit. The sequence is: SOH % / STX.
3. If the device buffer is unformatted, all alphameric
data in the buffer is included in the data stream (nulls
are suppressed). If the device buffer is formatted, only
fields that have the MDT bit set will be included in the
data stream following the Test Request Read heading.

5.2.7 Read Modified All (SNA Only)
1. The Read Modified All command is sent only by the
primary logical unit (host application).
2. A read-modified operation is performed, and all modified
fields in the selected device are sent to the host,
regardless of the AID byte generated.

5.2.8 No Operation (Models Band D Only)
1. The No Operation command performs no functional
operation at the CU.
2. Interface operation only.

5.2.6.1 Read Modified Read
1. The Read Modified Read command transfers the contents of the addressed device buffer to the CU buffer.
2. Data stream transferred to the host includes the AID
character, the cursor address, and all fields in which the

5.2.10 Sense (Models Band 0 Only)
1. The Sense command is issued by the program in response
to unit-check status.
2. I nterface operation only.
3. Transfers one byte of sense data from the CU to main
storage.

5.2.11 Copy [Model C (BSC)]
1. The Copy command transfers the contents of one device
buffer to another device buffer via the CU buffer.
2. The device whose contents are transferred is called the
from device.
3. The receiving device is called the to device.
4. The to device is selected in the addressing sequence.
5. Two bytes always follow the command byte: (1) the
copy control character (CCC) and (2) the address of the
from device.
6. The CCC performs a function similar to that of the WCC
in the Write and Erase/Write commands.
7. The from device buffer can be locked (incapable of
being copied) by storing a protected alphameric
attribute character in buffer address O.
8. The addressed device (that is, the to device) may also
be specified as the from device. This permits troubleshooting the Copy command with a single device.

5.3 CONTROL UNIT ORDER SUMMARY
See Figure 5-2 for control unit order codes.

5.3.1 Set Buffer Address (SBA)
The Set Buffer Address (SBA) order loads data, starting at
the address immediately following the SBA character.
The format is: SBA, address, address.

5.3.2 Start Field (SF)
The Start Field (SF) order specifies the next character as an
attribute character.
The format is: SF, attribute character.

5.3.3 Insert Cursor (IC)
The Insert Cursor (lC) order changes the address in the CU
buffer and thus repositions the cursor on the display screen.

5.2.9 Select (Models Band D Only)
The Select command transfers the contents of the addressed
device buffer to the CU buffer.

SY27-2512-3

5-1

SY27 -2512-3
Because the CU buffer address is not advanced when the IC
order is loaded in the CU buffer, the next byte is stored at
the cursor address.
The format is: IC.

5.3.4 Repeat to Address (RA)
The Repeat to Address (RA) order loads a single character
repeatedly, starting at the current CU buffer address and
continuing to, but not including, the address specified in
the order sequence. The cursor is not affected.
The format is: RA, address, address, character.

The cursor is unaffected, and no wraparound occurs. The
search begins at the current buffer address. The final result
depends on one of three conditions:
1. When PT immediately follows a data character within an
unprotected field, all remaining characters within that
field are replaced by nulls.
2. When PT immediately follows a WCC or an order
sequence, no nulls are inserted.
3. When the current buffer address contains an attribute
character that defines an unprotected field, the CU buffer address is simply advanced one character location.
The format is: PT.

5.3.5 Erase Unprotected to Address (EUA)

5.3.7 New Line (NL)

The Erase Unprotected to Address (EUA) order deletes all
unprotected-field characters beginning with the character at
the current address to, but notinc/uding, the character at
the address specified in the order sequence. If the address
specified in the order sequence equals the current address,
wraparound occurs, and all unprotected characters are
deleted. The attribute characters defining the unprotected
fields are not deleted.
The format is: EUA, address, address.

When included in the data stream addressed to a printer,
the New Line (NL) order initiates a carrier return/line
feed (CR/LF) operation by the printer. That is, the platen
is advanced one line and the print mechanism is returned
to the first print position of the new line. If this order is
included in the data stream addressed to a display, the N L
order is displayed as the number 5 (space 5 for Katakana),
but does not cause action in the CU or display. In any case,
it is stored in the CU buffer as the number 5 (space 5 for
Katakana).
The format is: N L.

5.3.6 Program Tab (PT)
The Program Tab (PT) order advances the CU buffer address
to that of the character position immediately following the
next attribute character that defines an unprotected field.

~
Sequence

The End of Message (EM) order must be included at the
end of a message addressed to a printer to notify it when to

Byte 1
(Order Code)

Order

EBCDIC
(Hex)

ASCII
(Hex)

Start Field (SF)

Attribute
1
Character

Set Buffer Address (SBA)

1st Address
Byte3

2nd Address
Byte 3

I nse rt Cursor (I C)

Program Tab (PT)

Repeat to Address (R A)

1st Address
Byte 3

2nd Address
Byte 3

1st Address
Byte 3

2nd Address
Byte 3

Erase Unprotected
to Address (EUA)
1 Figure

5.3.8 End of Message (EM)

Byte 2

Byte 3

Byte 4

Character
to Be
2
Repeated

5-12 shows coding of this byte.

2Figures 5-3, 5-4, 5-5, and 5-19 show coding of this byte.

5-2
stop printing. If the EM order is not included at the end of
the printer message, the printer will print out the contents
of the complete printer buffer (either 480 or 1920 characters). If this order is included in the data stream addressed
to a display, the EM order is displayed as the number 9
(space 9 for Katakana), but does not cause action in the
CU or display. In any case, it is stored in the CU buffer as
the number 9 (space 9 for Katakana).
The format is: EM.

5.3.9 Duplicate (DUP)

When the Carriage Return (CR) order code is found in the
data stream, the next print position will be the leftmost
character position on the current print line. CR orders are
not executed when they occur in non print fields, and
when the printer format bits in the WCC indicate a line
length (40,64, or 80 characters). In both cases, the CR
order is printed as a space character.

5.4 I/O INTERFACE CODES

The Duplicate (DUP) order informs the program that the
DUP key was pressed by the display station operator. Its
actual function is determined by the CPU program. The
DUP order is displayed as an asterisk (*) with overscore. It
is stored in the CU buffer, but does not cause action in the
CU.
The format is: DUP.

5.3.10 Field Mark (FM)
The Field Mark (FM) order informs the CPU program that
the FM key was pressed by the display operator. It indicates the end of a field to the program. The FM order is
displayed as a semicolon (;) with overscore. It is stored in
the CU buffer, but does not cause action in the CU.
The format is: FM.

5.3.11 Forms Feed (F F) (3262, 3287, 3288, and
3289 Printers)
Valid Forms Feed (F F) orders are executed by the 3287,
3288, and 3289 Printers during printouts, both with and
without a line-length format specified. (The FF order is
described in the section "Page Length Control/VFC Operations," in the IBM 3270 Information Display System:
3274 Control Unit Description and Programming Guide,
GA23-0061. When a valid FF order is encountered in the
first print position of a line, with the Page Length Control/VFC feature installed, the print form indexes to a
predetermined print line on the next form.

5.3.12 Suppress Index (SI) (3288)
The 3288 Printer, when equipped with the Text Print
special featu re, honors the Suppress Index (S I) order code.
The SI order causes printing of two or more lines of data at
the same paper position. The SI order is transferred as part
of the data stream from the application program and is
stored in the printer buffer as data.

3 The IBM 3270 Information Display System: 3274 Control Unit Description and Programmer's Guide, GA23-0061, lists the two-byte

code for each possible address. To be a valid address:
a.

5.3.13 Carriage Return (CR) (3262,3287 with
3274/3276 Attachment, and 3289 Printers)

If the Erase/Write Alternate command is not used, the maximum address is 479 for 3278 Model 1 displays or 1919 for 3277 Model 2
and 3278 Models 2, 3, and 4.

b. If the Erase/Write Alternate command is used, the alternate buffer size is specified by the model or bind parameter (959, 1919,2559,
or 3439).

Figure 5-2. Buffer Control Orders and Order Codes

The I/O interface codes for the 3274 Control Unit are
illustrated in Figures 5-3 through 5-12, and 5-19.

Bits

00
Hex
Bits
4567

0000

0001

0010

0011
0100

01
1

NUL

10
2

11
3

10
6

00
8

-- -j

·,
I

•

1000

,
!

s
t

1011

1100

1101

1110

1111

$
FF

DUP

S
T

0000

0001

0010

0011

11 ~ 2,3

{

}

NUL

0100

0101

0110

.I
:

ml1

1101

1110

1111

' j
¢

I
I

(

--,

0
1
2
.

:·•
:,

---- -r

·:

$
DUP

1100

;

·
,

~ Hex

1011

)

I
I

1010

1001

T
f

-1--

0,1

(

f.4-

--,

1000

Hex
Bits
4567

I
6A

...- 2,3
..-..- Hex 0

EM
!

~---

1010

8
9

... -

1001

... ( ... )

0110

0101

f-4-- 0,1

Notes:
1. Character code assignments other than those shown within all outlined areas of this chart are undefined. If an undefined character
code is programmed, the character that will be displayed or printed is a hyphen. The character displayed by the 3276 or 3278 for
a given undefined character code may be different for other devites. IBM reserves the right to change at any time the character
displayed for an undefined character code.
2. NL (hex 15), EM (hex 19), FF (hex DC)' and NUL (hex DO) are not displayed or printed. The DUP (hex lC) and FM (hex lE)
control characters on Dual Case featured terminals are displayed as and;respectively, and are printed as * and ;.
3. Dup (hex 1C) and FM (hex 1 E) control characters on Mono Case terminals are displayed as * and; respectively, and are printed
as * and ;.

Notes:
1. Character code assignments other than those shown within all outlined areas of this chart are undefined. It an undefined character
code is programmed, the character that will be displayed is not specified. The character displayed by the 3277 or 3275 for a given
undefined character code may be different for other devices. IBM reserves the right to change at any time the character displayed
for an undefined character code.
2. Lowercase alphabetic characters (shown within the dotted outlined area) are converted to uppercase by the display station or
printer and displayed or printed as uppercase characters, unless the terminal has Dual Case capability.

Legend:

Stored as a lowercase symbol. Displayed on Mono Case display only. Blank on Dual Case
display. Cannot be entered from keyboard

Figure 5-4. United States EBCDIC I/O Interface Code for 3274 Control Unit and Attached 3262,3278,3279,
3287, and 3289 Terminals

~ or ~ = Stored as Hex code shown. Nondisplayed on Mono and Dual Case displays.

Figure 5-3. United States EBCDIC I/O Interface Code for 3274 Control Unit and Attached 3277 Display Stations

SY27-2512-3

5-3

SY27 -2512-3
5-4
Bits
Hex 1
Bits
4321

000
0

001

010

011

100

101

110

~7,6,5

111

0010

0011

0100

0101

0001

NUL

(

1011

;

[

1100

1101

1110

1111

o_J_

0110

0111

1000

1001

1010

DUP

Sound

Alarm

Kybd
Restore

Bits

Bit
Bit
0
1

Explanation

Sound
Alarm

Type of Data
to be Copied

Explanation

Determined by the contents of bits 2-7 as shown in Figure 5-19.

Must be a 1.

2,3

Reserved (must be a 1).

Define the printout format as follows:
'" 00 - The NL, EM, and CR- orders in the data stream determine print line
length. Provides a 13,2-print position line when the orders are not present.

Define the printout format, as follows:

= 01'- Specifies 40-character print line ..

= 00 -

'" 10 - Specifies 64-character print line.

Determined by the contents of bits 2-7 as shown in Figure 5-19.

The NL, EM, and CR* orders in the data stream determine print
line length. Provides a 132-print position line when the orders are
not present.
'" 01 - Specifies 40-character print line.
= 10 - Specifies 64-character print line.
'" 11 - Specifies 80-character print line.
4

Start Printer bit. When set to 1, initiates a printout operation at completion
of the write operation.

1"~-

The Sound Alarm bit. When set to 1, sounds the audible alarm at the
selected device at the end of the operation if that device has an audible alarm.

The Keyboard Restore bit. When set to 1, restores operation of the keyboard
by resetting the INPUT INHIBITED indicator on 3275 and 3277 displays,
and the System Lock or Wait symbol on 3276 and 3278 displays. It also
resets the AID byte at the termination of the I/O command.

Reset MDT bits. When set to 1, all MDT bits in the selected devices'
existing buffer data are reset before any data is written or orders are
executed.

Figure 5-5. United States ASCII I/O Interface Code for 3274
Control Unit and Attached 3262,3278, 3279,3287,
and 3289 Terminals

SWt
Print

Figure 5-8. Format of Copy Control Character (CCC) Byte

}

Notes:
1. Character code assignments other than those shown within all outlined
areas of this chart are undefined. If an undefined character code is programmed, the character that will be displayed is not specified. The
character displayed by the 3277 or 3275 for a given undefined
character code may be different for other devices. IBM reserves the
right to change at any time the character displayed for an undefined
character code.
2. Lowercase alphabetic characters (shown within the dotted outlined
areal are converted to uppercase by the display station or printer and
displayed or printed as uppercase characters, unless the terminal has
Dual Case capability.

Printout
Formet

Figure 5-6. Format of Write Control Character (WCC) Byte

-i:

Re~et

MDT

"Determined by the configuration of bits 2-7. See Figure 5-19.

I {

Start
Print

*Determined by the configuration of bits 2-7. See Figure 5-19.

2,3
EM

Printout
FOI'rTllt

~HexO

0000

*The CR order is applicable to the 3262, 3287 and 3289 Printers only.

Figure 5-7. Function of Write Control Character (WCC) Bits

'" 11 - Specifies 80-character print line.
4

The Start Printer bit. When set to 1, initiates a printout operation at the "to"
device after buffer transfers are completed.

The Sound Alarm bit. When set to 1, sounds the audible alarm at the "to" device
after buffer transfers are completed if that device has an audible alarm.

6, 7

Define the type of data to be copied as follows:
Only attribute characters are copied.
'" 01 - Attribute characters and unprotected alphameric fields Oncluding nulls)
are copied. Nulls are transferred for the alphameric characters not copied
from the protected fields.

= 00 -

'" 1 0 - All attribute characters and protected alphameriC fields (including nulls)
are copied. Nulls are transferred for the alphameric characters not copied
from the unprotected fields.
-= 11 - The entire contents of the storage buffer (including nullsl are copied.
Note: A eee and address byte must always follow the command code; if they do not, the control
unit aborts the command and generates error status.
*The CR order is applicable to the 3262, 3287, and 3289 Printers only.

Figure 5-9. Function of Copy Control Character (CCC) Bits

3277·1
480

3277·2
1920

3276/8·'
960

3276/8·1
480

3276/8·2
1920

3276/8·3
2560

3276/8·3
1920

3276/8-4
3440

3276/8-4
1920

From
3277-1
480

•

3277-2
1920

960

•

3276/8·1
480

•

3276/8·3
1920
3276/8-4
3440

•A
v

Transfer
Transfer
Transfer
Transfer
Transfer

No AID generated
(Display or Display Station)

Rd Mod
(Unsolicited Read or
Read Modified from
Host)

Rd Mod

•

No A I D generated
(Printer)

•

ENTER key and &
(Selector Pen Attention)

PF 1 key

PF 2 key

Rd Mod

PF 3 key

Rd Mod

PF 4 key

Rd Mod

PF 5 key

Rd Mod

PF 6 key

Rd Mod

•
v

(See
Note)

PF 8 key

Rd Mod

PF 9 key

Rd Mod

PF 10 key

Rd Mod

PF 11 key

7B! See

Rd Mod

PF 12 key

Rd Mod

PF 13 key

Rd Mod
Rd Mod

allowed, no change in screen state required.
not allowed, Operation Check returned to host.
allowed, no change in screen state (appearance on "from" and "to" device may diffed.
allowed, screen state changes to alternate size.
allowed, screen state changes to default size.

Note.

Resultant Transfer to CPU

If performing a remote
polling operation, no read
operation occurs; otherwise
field addresses and text in
the modified fields are
transferred.

Rd Mod

PF 7 key

Legend:
0

Read Modified
Command Operation

•

3276/8-4
1920

Graphic
Character

•

3276/8-3
2560

Hex
Character
(ASCII)

•

3276/8-1

3276/8-2
1920

AID, Model B

Hex
Character
(EBCDIC)

PF 14 key

PF 15 key

Rd Mod

PF 16 key

Rd Mod

PF 17key

Rd Mod

PF 18 key

Rd Mod

PF 19 key

Rd Mod

PF 20 key

Rd Mod

AID code and cursor
address, followed by an
SSA order, attribute
>- address + 1. and text for
each modified field. Nulls
are suppressed.

Note: The 3440 screen does not have a 2560 mode. Therefore, the screen size is set to 3440.

Figure 5-10. Buffer Transfers for 3274 Model C (BSC) Copy Command Operation

PF 21 key

Rd Mod

PF 22 key

Rd Mod

PF 23 key

Rd Mod

PF 24 key

Rd Mod

Card Reader

Rd Mod

Alphameric MSR/MHS

Rd Mod

Selector Pen Attention
space null

Rd Mod

PA 1 key

Short Rd

PA 2 (CNCL) key

Short Rd

PA 3 key

CLEAR key

Short Rd

TEST REO and SYS REO keys

Tst Req Rd

Short Rd

AID code, cursor address,
and field addresses only;
no data.

AID code only.

A test request message.
AID transferred on Read
8uffer only.

Note: Graphic characters for the United States I/O interface codes are shown. If a World Trade I/O interface code is used, refer to the
IBM 3270 Information Display System: Character Set Reference manual, GA27-2837, for possible graphic character differences.

Figure 5-11. Attention I D (AI D) Configurations

SY27-2512-3

5-5

SY27-2512-3
5.4.1 Examining 3278 Attributes and Modified
Data Tags

ATTRIBUTE CHARACTER BIT DEFINITIONS
FOR 3278s AND 3279s
Attribute

I I I
X

EBCDIC Bits 0

EBCDIC
Bit 0,1
Bit 2*
Bit 2*
Bit 2, 3
Bit 3
Bit3
Bit 4, 5*
Bit 4, 5*
Bit 4, 5*
Bit 4, 5*
Bit 6
Bit 7
Bit 7

1, 1

=0
1

0,0

I/SPD

II
0

MDT

= 0, 1
= 1,0
= 1,1
=0

=0
= 1

"See Figure 5-16 for 3279 specifics.

Attribute

Prot

A/N

MDT
On

U
U
U
U

High
I ntens

Sel
Pen
Det

Non·
disp
PRT

V
V
V

U
U
U
U

H
H

V
V

U
U
U
U

N
N
N
N

U
U
U
U

N
N
N
N

P
P
P
P

V
V
V

H
V

V
V
V
Y

V
V
V
V

P
P
P
P

H
H

V
V

P
P
P
P

S
S
S
S

P
P
P
P

S
S
S
S

H = High
N = Numeric
P = Protected

V
V
V

V
V

H
H

V
V
V
V

Bits
4567

Hex

00
00
00
00

0000
0001
0100
0101

40
Cl
C4
C5

C8
C9
4C
4D

00
00

1000
1001
1100
1101

01
01
01
01

0000
0001
0100
0101

50
Dl
D4
D5

01
01
01
01

1000
1001
1100
1101

D8
D9
5C
5D

10
10
10
10

0000
0001
0100
0101

50
61
E4
E5

10
10
10
10

1000
1001
1100
1101

E8
E9
5C
6D

11
11
11
11

0000
0001
0100
0101

FO
Fl
F4
F5

11
11
11
11

1000
1001
1100
1101

Fa
F9
7C
7D

00
V
V

Auto Skip
U = Unprotected
V = Yes

To examine data on a 3278 for proper attributes and the
setting or resetting of modified data tags (MDTs), use the
following procedure. On D-type 3278 displays, use step 1
only; on M-type 3278 displays, use steps 1-6:

Determined by contents of bits 2-7.
Unprotected data.
Protected data - Auto lock.
Auto skip.
Alphameric data.
Numeric data - Auto shift.
Normal intensity/Nondetectable.
Normal intensity/Selector-Pen-Detectable.
High intensity/Selector-Pen-Detectable.
Nond isplay /Nonpri nt/Nondectab Ie.
Reserved. Must be zero.
Field data not tagged as modified.
Field data tagged as modified.

A/N

U/P

5-6

Graphic
Display

C ,
z

)
I

S
B

= rn
....
~
~

1. Place the CE jumper, as shown in Figure 5-13, on the
A-gate top-card connector that connects card F2 to card
G2 on the A-gate with three base cards, or card F4 to
card G4 on the A-gate with two base cards (Figure 5-14).
2. When data you wish to examine is displayed on the
screen, place the cursor in an area before the field in
question. Use normal cursor move keys unless input
inhibit or other condition prevents this. (See step 4 if
you cannot move the cursor as directed.)
3 .. Place the NormallTest switch in the TEST position.
(The CE jumper on the A-gate will inhibit POR and test
pattern generation, forcing test mode 3-display of the
device regen buffer.)
4. If you are unable to move the cursor to the proper area
in step 2, use test mode 3. Press Reset, then the E key
and 0 key; press Reset, then the U key and / key; press
Reset, then the D key 19 times. This places the cursor
in position 1 on the screen. You may continue with the
D key to read; or press Reset, then the E key, and press
1 through 7 to select another 256-byte block of data.
5. When the cursor is in an area before the field in question, press Reset and the D key; then conti nue Read by
use of the typamatic function of the D key until you
reach the desired field.
6. The status area (the first character of the operator information area) will contain the graphic equivalent of the
attribute or data character each time the D key is
pressed, and it can be examined to check that the
attribute/MDT is correct. (See Figure 5-12.)

Connector Handle

/p;n2

N
/

;;.

i
·'.1

;".

...
~
-

•••
•••
•••
••
•

=v
•

• 7t-----.
••.-...:.....
•

•••

•••
•
••
••

Pin 008
See Note

1. Place the CE jumper as shown in Figure 5-15.
2. Position the cursor at the location where the attribute
is to be displayed.
3. Place the Normal/Test switch in the TEST position.
Nulls will display as 1::Y and attributes will be blank.
Note that base white and red change to red and white,
respectively.
4. Press CONTROL D. The character, or attribute, at the
cursor position is copied into the first position of the
operator information area and the cursor advances.
5. Refer to Figure 5-16 to determine if the attributes are
being interpreted correctly by the hardware .
Connector Handle

I
p

;n7

CEJumpm

Pin 8

Figure 5-12. Attribute Character Bits
Figure 5-13. 3278 Top-Card Connector CE Jumper (Three
Base' Cards)

GREEN

BLUE

GREEN

YES

BLUE

YES

o
o

•••

•••
••
••
••
Figure 5-15. 3279 Top-Card Connector CE Jumper

RED

YES

WHITE

YES

Non Display

Figure 5-16. 3279 Base Field Attributes
EXTENDED FIELD AND CHARACTER ATTRIBUTES

3274 is customized to include the extended data stream (EDS)
function

•

Attached devices have the Extended Character Set Adapter
(ECSA) feature

ECSA
Buffer

Extended
Field

Character attributes

Alphameric characters

Sel Pen
Detectable

•

To examine data in the 3279 refresh buffer (not the ECS
buffer) for proper attributes and the setting or resetting
of modified data tags (MDTs), use the following procedure:

Color of
Field

5.4.2 Examining 3279 Attributes and Modified
Data Tags

Note: There is no top-card connector if the selector pin card is not
installed. Use card shroud Pin DOB to D09.

Pin 8

Figure 5-14. 3278 Top-Card Connector CE Jumper (Two
Base Cards)

.'--_~__

Pin D09

Internal extended field and character attribute bit assignments
are summarized below:
Bit

Field Description

0,1

Extended Highl ighti ng
00 = Normal mode (revert to extended field
if character attribute)
01 = Blink
10 '" Reverse video
11 = Underline

2,3,4

5,6,7

Color
000 = Default to base color (revert to extended
field if character attribute)
001 = Blue
010 = Red
all '" Pink
100 = Green
101 = Turquoise
110 = Yellow
111 = White
Program Symbol selection
000 = Base character generator (revert to extended
field if character attribute)
001 '" APL/Text character generator
010 = PS A
011 '" PS 8
100 = PS C
101 = PS 0
110 = PS E
111 '" PS F

x
a

u/P

AIN

Reserved

D/SPD
5

Bits 2-7

MDT

00
Field Description
Value determined by contents of bits 2-7.

Must be a 1.

'" Unprotected

1 '" Protected

- a

= Alphameric
1 '" Numeric (causes automatic upshift of data
entry keyboard)

Note: Bits 2 and 3 equal to 11 causes an
automatic skip. See text.
4&5

00 = Display Inot selector-pen-detectable
01 '" Display Isel ector-pen-detectable
10 = I ntensified display Iselector-pen-detectable
11 '" Nondisplay, nonprint, nondetectable

ASCII

Bits 2-7

0000
0001

SP
A

Graphic

EBCDIC

ASCII
20

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

¢ ,[

1010

1011

I (EBCDIC)
I

1100

1101

(

1101

1110

1111

+
I, !

1111

Reserved. Must always be O.

Modified Data Tag (MDT); identifies modified
fields during Read Modified command
operations.

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

I,]

1010

1011

1100

2. To examine data for proper attributes and the setting or resetting
of modified data tags (MOTs) use (he fol/owing procedure:

1101

)

1101

1110

;

1110

a. Jumper J2M13 or H2D07 to Gnd (008). 3277s with APL
Text should also jumper K2B07 to Gnd (attribute byte
of "60" will not be displayed).

1111

""",1"\

1111

'"
"

'" Field has not been modified
1 = Field has been modified by the operator.
Can also be set by program in data stream.

Notes;

Figure 5-17. Extended Field and Character Attributes

EBCDIC

00
EBCDIC
Bit

Graphic

1. Bits 0 and 1 are not decoded when received by the 3270. When
characters are being transferred to the CPU, bit 1 is a 1 and bit 0
is set, depending upon the character being transferred. All
attribute characters are part of the defined character set. The
default option (bits 2 through 7 al/ set to 0) results in an unprotected, alphameric, displayed, nondetectable field.

b. A ttribute and nondisplay fields will now be displayed and
can be compared with Figure 5·19.
c.

Remove the jumpers when completed.

Figure 5-18. Attribute Character Bit Assignments for 327:1s

Note: The following characters are used as attribute, AID, write control (WCC), copy control (CCC), CU and device address, and buffer
address. They are also used as status and sense, except by the 3274 and 3276 when operating in BSC. When any character is received by
the CU, only the low-order 6 bits are used. When any of these characters is. transmitted to the program, the CU assigns the appropriate
EBCDIC code. If transmission is in ASCII, the CU translates the EBCDIC code to ASCII code prior to transmission.
For example, to use this table to determine the hex code transmitted for an attribute character, first determine the values of bits 2-7.
Select this bit configuration in the table under "Bits 2-7'~ The hex code that will be transmitted (either in EBCDIC or ASCII) is to the
right of the bit configuration.
Use this table also to determine equivalent EBCDIC and ASCII hex codes and their associated graphic characters.
Graphic characters for the United States I/O interface codes are shown. If a World Trade I/O interface code is used, refer to the IBM
3270 Information Display System: Character Set Reference manual, GA27-2837, for possible graphic character differences.

Figure 5-19. Control Character I/O Codes

SY27 -2512-3

5-7

SY27 -2512-3
5.5 SEQUENCE/RESPONSE DIAGRAMS,
MODELS A, S, AND D
Figures 5-20 through 5-23 give the events, in sequence, that
occur during selector channel operations. The Channel
column includes Tag Out lines from the host (360 or 370).
The Bus column includes Data on the Bus Out lines from
the host and Data on the Bus In lines from the control unit
(Model B). The Control Unit column includes Tag In
lines from Models A, B, and D.
Channel
(Tag Out.... )

Control Unit
(4-Tag In)

Bus

Channel
(Tag Out+)

Raise
Service Out

Raise
Hold Out

Raise
Service In

Drop
Service Out

Raise
Service Out

Raise
Service In

Drop
Service In

Raise
Command Out

Raise
Operation In
Drop
Address Out

Drop
Service In
Drop
Command Out

Raise
Address In

Command ...........

Drop
Command Out

Raise
Service Out

Drop
Service Out

Figure 5-20. Initial Selection

Drop
Address In

Drop Hold Out
and Select Out
and Rise Service
Out

Ending Status

Raise
Status In
Drop
Status In and
Operational In

Figure 5-21. Write-After Selection with Write Command
Raise
Status In

1__ Initial StaM

I
Drop
Service Out

Drop
Status In

(Repeat until end
of data or until
host data byte
count equals
zero.)

I
I
I

Raise
Service Out

Drop
Service Out

Channel
(Tag Out .... )

Drop
Service In

I
~

Ending Status

Raise
Service Out

Drop
Service Out

I
I
I

\1---

Raise
Service In

Drop
Service In
Drop
Service Out
Raise
Status In

Drop
Status In

Figure 5-22. Read-After Selection with Read Command

Bus

""4-- Sense Data

I
I
I
I
I

Raise
Service In

Raise
Service Out

Raise
Command Out

Drop
Command Out

Control Unit
(~Tag In)

Last Data Byte

Raise
Service In
(Check Address)

Bus

I _ D a t a Byte

Drop
Service Out

CUAdd""_1

____ C U Add ress

Channel
(TagOut ... )

Drop
Service In

Raise
Select Out

Raise
Command Out

Control Unit
(4-Tag Inl

Data Byte ___ ,

Raise
Operational Out
Raise
Address Out

Bus

5-8

I
I
I

Endi ng Status

I
I
I

Control Unit
(-Tag In)
Raise
Service In

Drop
Service In

Raise
Status In

Drop
Status In

Figure 5-23. Sense-After Selection with Sense Command
(Issued in Response to Unit Check Status)

5.6 STATUS AND SENSE BYTE DEFINITIONS
5.6.1 Description
Figures 5-24 through 5-28 give the 3274 Control Unit sense
and status byte definitions.
Bit

Name

Condition

Bit

Name

Significance

Attention
(AI

I ndicates a request for service from a 3277 attached to a 3272, or a 3277 or 3278 attached to a
3274. Set as result of certain keyboard, selector pen, or card reader activity at 3277 or 3278
(see Figure 5-111. Program should respond by issuing a Read Modified command !chained
from a Select command if multiplexer channell to the 3277 or 3278 requesting attention.
Attention bit is also set with Unit Check bit as result of asynchronously detected equipment
malfunction; in this case, program should respond by issuing a Sense command.

Command Reject (CR)

Set if the 3272 or 3274·8 has received an invalid command; the valid
commands are listed in Figure 5-10.

Intervention Required (tR)

Set if a command, other than Sense, was addressed to a device that is·
unavailable or is in the "not ready" condition.

Bus Out Check (BOC)

Set if the 3272 or 3274-8 has detected bad parity on any command or data
byte received from the channel.

Status
Modifier
(SMI

Is set, with Busy bit, in initial status byte to indicate that there is pending status for a
device other than the one selected.

Equipment Check (EC)

Control
Unit End
(CUE)

Is set following a busy condition, after pending status is cleared or when control unit is no
longer busy, to indicate that control unit is now not busy and is free to accept a new
command.

Set if: (1) the 3272 or 3274-8 has asynchronously detected a parity check
on data received from a device in response to an internal poll for attention
status (the internal poll is tried twice before EC is set), (2) a printer error
occurs. If this is a device-detected condition, Unit Specify is also set.

Data Check (DC)

Busy (BI

Is set alone in initial status byte when addressed device is busy because it is performing a
print operation or an Erase All Unprotected command. Set with SM when addressed
control unit is busy. When the channel addresses a device other than the one that is busy
and control unit is not busy. addressed device becomes selected and the command is
honored. Busy bit is also set with pending status if addressed device has such status; if
pending status is for a device other than the one addressed, Status Modifier bit is also set.

Set if: (1) the 3272 or 3274-8 or a device has detected bad parity on data
transferred internally or between the 3272 or 3274-8 and a device during
command operations, (2) a 3277 or 3278 has detected a cursor check, or
(3) a device has detected a buffer check. If this is a device-detected condition, Unit Specify is also set.

Unit Specify (US)

Set if the sense bits resulted from a device-detected error.

Control Check (CC)

Set when the 3272 or 3274-8 has detected a timeout condition. (The
addressed device fails to perform a specified operation or respond to the
3272 within a specified period of time.)

Operation Check (OCl

Set when the 3272 or 3274-8 has received a valid command or" order that it
cannot execute, as follows:
1. S8A, RA, or EUA order specifies an invalid buffer address.
2. Write data stream ends before all required bytes of S8A, RA, EUA, or
SF order sequence are received.
3. Write, Erase/Write, or Erase/Write Alternate with Start Print bit set in
WCC is chained to the next command; the print operation is suppressed.

Channel
End (CE)

Indicates channel data transfer operations are completed. Is set alone (1) in initial status
for Select or Erase All Unprotected command, or (2) as ending status for Write, Erase/
Write. or EraselWrite Alternate command; in all cases, Device End status is sent
asynchronously when device operations (command execution or control unit-to-device
buffer transfer) are completed.
Is set with Device End, to indicate that control unit and device operations (except
printing) are completed (1) in initial status for No Operation command. (2) in ending
status for Read Buffer, Read Modified, or Sense command, or (3) asynchronously if only
Channel End status was pending and the device operation is completed before the channel
accepts status.
Is set with Device End and Unit Exception in initial status for Read or Write command if
addressed device is busy executing another command.

Device End
(DE)

Indicates that control unit and device have completed all command operations and are
free to execute another command. Is set (1) in initial status for No Operation command,
(2) in ending status for Read Buffer, Read Modified, or Sense command, and (31 in
asynchronous status for Write, Erase/Write, EraselWrite Alternate, Select, or Erase All
Unprotected command.

Unit Check
(UC)

Is set when an irregular program or equipment condition is detected by control unit or
the device. Program should always respond to Unit Check status by issuing a Sense
command for further definition of condition.

Unit
Exception
(UE)

Is set in ending status (synchronous or asynchronous) when control unit has attempted to
execute a command but has found, after initial status was returned, that addressed
device was bUsy.

Figure 5-25. Sense Bit Description

Figure 5-24. Status Byte Bit Assignments for 3274 Models Band D

SY27-2512-3

5-9

SY27-2512-3
Status l
(Hex)

Sense
(Hex)

All Zeros

Display

Printer

Error Recovery
Procedure

Normal status for any command
other than No Operation, Select, or
Erase All Unprotected.

(00)

Normal status for ~ a Select or Erase
All Unprotected command.

Normal status for a No Operation
command.

(OS)

CE,DE
(OC)

BOC

(02)

(20)

(02)

(40)

(02)

(SO)

A parity check was detected on the
command byte.

A command other than Sense was
addressed to a device that the control unit has recorded as :'unavailable" or "not ready."

An invalid command was issued to
control unit.

(10)

B,SM

Condition

(50)

Response to a command addressed to
a device which is being serviced by
the control unit or which is completing a previously issued command.
Response to a command addressed to
a device other than device whose
status is pending or device being serviced by the control unit.

5-10
Sense
(Hex)

Status
(Hex)

Display

Printer

Error Recovery
Procedure

Condition

CE I
(OS)

Sent at end ot data stream on a Write, Erasel
Write, or EraselWrite Alternate command.

CE,DE I ,2
(OC)

Sent at end of data stream on a Read Buffer,
Read Modified, or Sense command or when
channel byte count goes to zero on a Read
Modified or Read Buffer command.

The control unit detected a parity error
on a character in data stream of a Write or
EraselWrite command.

DC, US
(OC)

Addressed device detected a parity or
cursor check during a Write, Read Buffer,
or Read Modified command. Also, the
3274 has disabled the device due to error
(UC, IR is reported on the retry since the
device requires a Power On Reset to be
reenabled) .

CE,DE,'UC 1 ,2
(OE)

DC
(OS)

The control unit detected a cursor or
parity check during receipt of data stream
on a Write, Erase/Write Alternate, or
EraselWrite command.

CE, DE, UC 1 ,2
(OE)

DC
(OS)

The control unit detected a cursor, or
parity check during transmission of data
stream on a Read Buffer or Read
Modified command.

Addressed device failed to respond in a
specified period of time to an EraselWrite,
or EraselWrite Alternate command or an
unchained Read Buffer, Read Modified,
or Write command. When attached tO,a
3274 Model 8, the addressed device was
found to be in Test mode or assig'1.ed as
a local copy device (UC, IR will be
reported on a subsequent operation).

The control unit received an invalid
buffer address in data stream of a Write,
EraselWrite, or Erase/Write Alternate
command, or data stream ended before
providing all characters required for an
SBA, RA, SF, or EUA order on a Write,
Erase/Write, or EraselWrite Alternate
command. Also, when the 3274 8
receives a write type command with
a WCC = X"SS".

The control unit attempted to perform a
Read Buffer, Read Modified, Write,
Erase/Write, or Erase/Write Alternate
command but found, after returning
initial status, that the addressed device
was "busy".

CE,DE,UC 2
(OE)

CE,DE,UC
(OE)

1,2

CE, DE, UC
(OE)

1,2

BOC
(20)

(02)

lit an SIOF is executed by the channel, unchained initial status becomes ending status.

Figure 5-26. Initi~1 Status and Sense Conditions for 3274 Models Band 0

CE, DE, UC
(OE)

CE, DE, UE 1 ,2
COD)

OC
(01)

llf this status is stacked by the channel, CUE could be generated and combined with it before the stacked status is accepted
by the channel.
20ccurs if a Start ilO Fast Release (SIOF) is executed by the channel for Select, Erase All Unprotected, or No Operation.

Figure 5-27. Ending Status and Sense Conditions for 3274 Models Band 0

Status
(Hex)

Sense
(Hex)

Display

Printer

Error Recovery
Procedure

A
(80)

DE
(04)

A, DE, UC
(86)

IR, EC, US
(54)

A printer became mechanically disabled
during a printout and an automatic
recovery was not successful, the printer
CARRIAGE MOTOR POWER switch was
off, or the switch fuse was blown.

DE,UC
(06)

IR, EC, US
(54)

A command attempted to start a print
operation, but the printer CARRIAGE
MOTOR POWER switch is turned off.

A, DE, UC
(86)

EC,US
(14)

A printer character generator of sync
check error occurred or the printer
became mechanically disabled during
printout, but restored itself.

DE,UC
(06)

DC
(OS)

During a Select, Erase/Write, or Erase/
Write Alternate command the control
unit (1) detected a parity or cursor error,
or (2) detected a parity check on data
received from the addressed device in
response to an internal poll during a
command.

DE,UC
(06)

DC
(08)

During a Write command, the control
unit (n detected a parity or cursor error,
or (2) detected a parity check on data
received from the addressed device in
response to an internal poll during a
command.

DE,UC
(06)

DC,US
(OC)

The addressed device detected a parity
or cursor check while executing a Select,
Write, EraselWrite, Erase/Write Alternate,
or Erase All Unprotected command.

DE,UC
(06)

OC
(01)

A Write, EraselWrite, or Erase/Write
Alternate command, containing a WCC
with a Start Print bit, is chained to a
subsequent command.

DE,UC
(06)

CC
(02)

The '5272 Online/Offline switch is
thrown from Offline to Online and an
attention-generating action (e.g., program
access key has been depressed) was performed by the operator.

A,UC
(S2)

EC
(10)

An idle 3272 polled a device twice and
detected a "transmit" parity check each
time on the data in the device reply.

A,UC
(S2)

DC,US
(OC)

An idle device detected a parity check or
cursor check in its buffer or, an idle device
on a 3274 has been disabled due to controlunit-detected errors (UC, IR will be reported
on the next retry since the device requires
a Power On resetl.

4 or 8

Error Recovery
Procedure

An attention-generating action (e.g., program
access key has been depressed) was performed
by the operator.

The 3272 Online/Offline switch is
thrown from Off Line to On Line. This
causes each "available" device to present a
Device End to the channel.
A,DE
(84)

Sense
(Hex)

Status
(Hex)

The control unit-to-device buffer transfer is
completed on a Write, Erase/Write, or Erase/
Write Alternate command which did not
start a printer.
The device becomes "not busy" after
completing an Erase All Unprotected command or the printer becomes "not busy"
after completing a printout.
The device-to-control unit buffer transfer
is completed on a Select command.
A device changes from "not available" to
"available" or from "not ready" to "ready".
A device becomes "not busy" after
having previously sent Unit Exception when
the control unit attempted to execute a
command with the device when it was "busy".

Condition

Display

Printer

Adevice on a 3272 changes from "not
available" to "available" or from "not
ready" to "ready" and has detected a
parity check or cursor check in its buffer
or a printer detected parity check while
printing.

A,DE,UC
(S6)

DC, US
IOC)

A,DE,UC
(S6)

IR
(40)

The addressed printer became Not Ready
(out of paper or cover open) before completion of a print operation.

DE,UC
(06)

IR
(40)

A command attempting to start a printer
found it Not Ready.

DE,UE
(05)

CUE
(20)

Condition

The addressed device failed to respond
in a specified period of time to a Select.
Write, Erase/Write. Erase/Write Alternate.
or Erase All Unprotected command, a
display was in Test mode, or a printer was
assigned as a local copy device. (UC,IRwili
be reported on a subsequent operation.)
The control unit attempted to perform a
Select or Erase All Unprotected command.
but found. after returning initial status,
that the addressed device was busy.
The control unit had been addressed wh ile
busy, but is now not busy and is free to
accept a new command.

Ilf this asynchronous status is stacked by the channel, an asynchronous CUE could be generated and combined with it before
the stacked status is accepted by the channel.

Figure 5·28. Asynchronous Status and Sense Conditions for 3274 Models Band 0

SY27·2512·3

5·11

SY27-2512-3
5.6.2 Error Recovery Procedures
The recovery procedures referred to in the Error Recovery
Procedure column of Figures 5-26, 5-27, and 5-28 are as
follows:
1. Reconstruct the entire buffer image and retry the failing chain of commands. The sequence of commands
used to reconstruct this image should start with an
Erase/Write command (or Erase/Write Alternate on a
3274 or 3276). If, after two retries, the problem is not
corrected, follow procedure 4.
2. The error indicates the device is "unavailable." Request
and wait for operator intervention to "ready" the
device; then, upon receipt of DE status, retry the chain
of commands.
3. A nonrecoverable program error has occurred. Examine the data stream to locate the problem.
4. Request maintenance for the device that is giving
trouble. After the repair, reconstruct the buffer
image, starting with an Erase/Write command (or
Erase/Write Alternate).
5. Record the error for future reference, and continue
with the program. This error occurred while the control
unit was "idle" and is not indicative of a data error.
6. The error indicates the printer is out of paper, has the
cover open, or has a disabled print mechanism. Request
operator intervention to "ready" the printer; then,
upon receipt of DE status, retry the print operation by
issuing a Write command with the proper wee and no
data stream. (There is no data error; the data is still
intact in the device buffer and can be reused.) If this
procedure is unsuccessful, follow procedure 1.

7. The error occurred during a printout and indicates
either a character generator or sync check error or a
disabled print mechanism. There is no buffer data
error. The proper error recovery procedure is application-dependent since the user mayor may not want a
new printout. Because the buffer contents are still
good, procedure 6 may be followed.
8. A data error occurred at the device during a printout.
This indicates a data error at the device; procedure 1
should be followed.
9. A device is busy but the control unit was not informed
of this in time to respond with Busy status in the Initial
Status byte. A DE status will be generated asynchronously when the device becomes not busy. After the DE
is received, retry the chain of commands that was being
executed when the Unit Exception (UE) status was
received.
10. Retry the failing chain of commands. If, after two
retries, the problem is not corrected, follow procedure 4.

5-12

Notes·:·

5.7 SEQUENCE/RESPONSE DIAGRAMS,
MODEL C, sse

D The 3274 will fail to respond to the addressing or polling sequence, causing a TCU timeout, for any of the following reasons:
•

Figures 5-29 th rough 5-33 provide the sequences and

The 3274 is "unavailable" (has power off, is "offline", or is not attached).

responses that occur during online SSC operation of the

•

Any character in the polling sequence is invalid.

3274 Model C.

•

The characters in the polling sequence are out of order.

•

The polling sequence is incomplete (less than seven charactersl.

•

The 3274 address is incorrect in the write data stream.

•

The addressed 3274 was left selected from the previous transmission.

I/O Surervisor/
Access Method

TCU Read Data
(Generated by 3274)

TCU Write Data
(From Channel Program)

CCW

fJ There is no I/O pending or pending status.

Starfl/O - _ - - Write (CC)....,. (Leading Pad and SYN Chars*»

EDT

II The device response is a function of the kind of device and its status. Types of responses include Text, Status, and Test Request

Control Unit

1 (Trailing Pad and SYN Chars*)

messages.

Generated

Write (CC)..,. 3274 Address (Poll)

I
I
I
Read

3274 Address (Poll)
Device or Gen Poll Address
Device or Gen Poll Address
ENG

I
I
I

I N~
1 Response

~.---+----------+I-

Interrupt: CE + DE + UC)
TCU Sense Bits: Timeout)

'(Operation Completed)

.......---~----------(Interrupt: CE + DE + UE)

o
I

I "

- - -1

--...-I--------J

, ___ ..J
I I
3274
I I
Response

, I~ETBB
C;;~C
: : ;~'Dm
: I

I...----+---Write (CC) - - - - - - N A K

m-----'----.,
I

-,----.. --------also
Read

(Interrupt: CE+DE;

EOT

,
-

_...J

For General Poll, this transmission stops the polling operation. The General Poll must be reinitiated to ensure receipt of all pending
device messages.
The text block has been successfully received by the TCU. The program issues ACK 1 in response to the first
and all odd-numbered text blocks and issues ACK 0 in response to the second and all even-numbered text blocks.

if) Normal termination of a Specific Poll.
Normal termination of a General Poll.

ill The second and all succeeding text blocks are framed as the first except they do not include the 3274/device address sequence.
ID RVI to terminate polling sequence.

1m Termination of polling sequence on receipt of RVI.
LEGEND:
(Interrupt) = TCU-generated interrupt (CE = Channel End, DE = Device End, UE = Unit Exception, UC = Unit Check).

m----...,:I--------------J

R~ad

A read-type command would violate BSC standards on Limited

Conversational mode.

(CC) = Chain Command (CC) Flag in CCW is set to 1.

+ UC if BCC error)
Start I/O (BCC E!ror)
(TCU Sense Bit: Data Check)1
....-----rl--,r-- Write (CC) --+1NA K

IIi] This tranSmission must be a write or control-type command sequence.

II Positive acknowledgment.

ETX

Upon detection of an internal parity check or a cursor check, the 3274 (1) substitutes the SUB character for the character in error,
(2) records Data Check status, and (3) transmits an ENQ in place of ETX (or ETB) and BCC at the end of the text block. The general
poll process is stopped.

by the 3274 to transmit the message. This response does not cause the 3274 to reset its sense/status information. Therefore, the
same status message will be transmitted if a Specific Poll is immediately issued to the same device.

, . - - - - - - - - - - - - - - - - - ' - - - (I nterrupt: CE + DE) ---1-;1---,1
Start I/O

For General Poll, the search for a response starts at some random device address and continues sequentially (as long as ACKs are received
in response to text transmissions) until all devices are given the opportunity to respond.

II Mandatory program response to a text block terminated in ENQ.
II Terminates the operation. The nature of the error (parity or cursor check) does not warrant a retry. This response indicates that status
and sense information is stored.
.
II ETB is used to frame each block of a blocked text message, except the last block. ETX is used to frame the last block of a blocked text
message.
D BCC error has been detected. The program issues NAK to cause the 3274 to repeat its last transmission.
II Response issued by the program to terminate the operation if the TCU is unsuccessful in receiving a valid BCC following "n" attempts

I
I

I ,

For General Poll, the CU sends EOT only after polling all devices.

*Only the critical framing characters (sync pattern and pad) are shown. All other framing characters are also hardware-generated as required .
See SL Genera/Information - Binary Synchronous Communications, GA27-3004, for a complete description.

""'""-Write-~:~-.-[-EOTm
J
. _...
Command Sequence

:
. ._ _ _~__
I

,
I

Write (CC)

..I..
Read
Write (CC)

(Write~or-Control-

Type)·

l A C K 1 or

a ill

I ,

.L
Read

,
Next text
block III

Read
Write (CC)

Figure 5-29

,
,

RVI

iII

General Poll and Specific Poll, Sequence/Response Diagram

•

Continue
General Poll

i
I EOT

11m

SY27-2512-3

5-13

5-14

SY27-2512-3
Notes:

TCU Write Data
(From Channel Program)

(Poll Sequence)

TCU Read Data
(Generated by 3274)

Status
Message*

Test Request
Message

D A status message response is issued to a General or Specific Poll if (1) the 3274 has pending status (General Poll ignores Device Busy
Read Partition

Read Modified or

(Query)
fJ
Short Read Message
II
•-........~~?~..~..........~................~..................~.-----SOH

SOH

R
STX
3274 Poll Address
Device Address

I
STX

O} 0

SIS
SIS 1
ETX
BCC

I.- (Interrupt)

STX
3274 Poll Address}
Device Address

Text
ETX or ETB
BCC

OLE
STX
3274 Poll Address
Device Address
Text
OLE
ETX

Bee
SUB
Text
ENQ

I
I

(I nterrupt)

(NAK)--~-------------------------------------------------------------------J

* Response to General Poll or Specific Poll only (!!2!. program-generated Read Modified command)

Figure 5-30. 3274 Message Response to Polling or Read Modified Command

and device "unavailable" and, if the 3274 continues polling of next device), or (2) if error status develops during execution of the
poll.

fJ A Test Request Message response is issued to a General or Specific Poll if a TEST REQ key is pressed at the keyboard of a polled 3277,
or if a SYS R EQ key is pressed at a 3278 or 3279 attached to a 3274 .
II This address is included only in the first block of a blocked text message.
II The text portion of this message is the result of either a Read Modified or Short Read operation by the 3274.
II The text portion of this message is the result of a Read Partition (Query) structured field function.
LEGEND:
(Interrupt)

= TCU-generated interrupt.

Notes:

I/O Supervisor/
Access Method

TCU Write Data
(From Channel Program)

CCW

Start 1/0_. . . ._ Write (CCI

Write (CC)

D The 3274 will fail to respond to the addressing or polling sequence causing a TCU timeout, for any of the following reasons:

TCU Read Data
(Generated by 3274)

•

~~;'ing Pad and SYN chars*'",,-

(Trailing Pad and SYN Chars*) ~ Hardware
3274 Address
Generated
3274 Address
Device Address
Device Address

The 3274 is "unavailable" (has power off, is "offline," or is not attached).

•

Any character in the polling sequence is invalid.

•

The characters in the polling sequence are out of order.

•

The polling sequence is incomplete (Jess than seven characters).

•

The 3274 address is incorrect in the write data stream.

•

The addressed 3274 was left selected from the previous transmission.

IIfJ The addressed device has pending status (excluding Device Busy or Device End).
II The addressed 3274 is busy. No SIS information is stored. An RVI response takes precedence over
a WACK response.

II The address has been successfully received and no status is pending.
II Termination of attempted addressing sequence:

ENQ

Availability of valid status and sense information cannot be ensured unless a Specific Poll is issued to the responding device as the
next addressing sequence issued to this 3274.

II Termination of attempted addressing sequence.
LEGEND:

Read

I Response
10

(I nterrupt: CE + DE + UC)
(TCU Sense Bit: Timeout)

(CC)

WACK

ACKO

= Chain Command (CC) Flag in CCW is set to 1.
= TCU-Generjrted interrupt (CE = Channel

(J nterrupt)

End, DE

= Device End, and UC = Unit Check)

-W
I

(Interrupt: CE + DE)

I
Start I/O

----t--- Write ---~- EOT II

,.,-----+---------..,...--(Interrupt: CE + DE ) - - - i - - - - - - - - - . J
Start I/O

..
I ___-+-_ Write --~t--- EOl

I.---...------...
Start I/O -

...-

writj (CC'

Read

-(lnterrupt:

CE DE)-----------..
+

Command Sequence

I
I

*Only the critical framing characters (sync pattern and pad) are shown. All other framing characters
are also hardware-generated as required. See SL General Information - Binary Synchronous
Communications, GA27-3004, for a complete description.
Figure 5-31. Selection Addressing, Sequence/Response Diagram

SY27-2512-3

5-15

SY27 ·2512·3
I/O Supervisorl
Access Method

CCW

(Selection or Poll
Seq or Previous
Command OpJ

TCU Write Data
(From Channel Program)

Read

device or one of the following:
a. receipt of an illegal command/order sequence,
b. failure to decode a v..alid command.
c. an I/O interface "overrun",
d. a parity/cursor check,
e. an illegal buffer address, or
f. a locked buffer.

STX

ESC

Command Code

I
I

Text.
ETX

(acC) Control Unit
Generated

In the case of the Copy command, the "from" device is busy or has locked buffer, or CCC is missing.

No
I Response

I
I

I B
CE + DE + UC) ~

.....- - - - - - - - - - - - - t l - ( I n t e r r u p t :
(TCU Sense Bit: Timeoutl

EOT

ACK 1 orO

II
NAK

II iii

IJ
WACK

L--,..-----+-------+--(lnterrupt: CE + DE1--.;.,I-_-..,J1

-I
Write ---+----EOT

I
r",------t--------+--Unterrupt: CE + DE + UE1-~-----...J
Start I/O
I

Write (CC)

--+- [Specific Poll Sequencel

"'1

Start I/O

1'------+--- Write - - - + - - - E O T

Example of a Temporary Text Delay (TTD) sequence.

lEI Example of terminating an operation using TTD (a forward abort sequence).

1[.

(CC)

Command Sequence]
such as Write
Command Code and
next block of text

I
(Continue)
I
'-"--_--......--write--~I-_
Read

TTD

STX

ENQ

I
I

Start I/O
I (Continue)

write-H

I
I

NAK

:~::~ri~~uence

Chain Command (CC) Flag in CCW is set to 1 .

(Interrupt) = TCU-generated interruption ICE = Channel End, DE = Device End, UE = Unit Exception, UC = Unit Check).

Write (CC)

II Normal termination of the operation by the program.
II Command execution has been successfully completed.
1m Repeat the operation shown in this figure for the next command sequence.

LEGEND:

(Terminate)
I
...---~-_Write!--..I---EOT
(Continue)

If a transmission problem causes both a 3274-detected check condition and a BCC error, the BCC error takes precedence over all
II other
check conditions, and a NAK is transmitted to the TCU.
Bee
error
or missing ETX has been detected. The NAK response requests the program to repeat its last transmission.
II
Response issued by the program to terminate the operation if the 3274 is unsuccessful in receiving a valid BCC following lin"
II attempts
by the program to transmit the message.
If the Start Printer bit is set in the WCC or CCC, a WACK response indicates that the text transmission was successfully received, but
II that
the printer is now busy and an additional chained command cannot be accepted.

Start I/O

The EOT response to a command transmission indicates that status information is stored in the control unit. To ensure retrieval of valid
status, the program must issue a Specific Poll (addressing the device that was selected when EOT was generated) as the next addressing
sequence to this control unit. Successful completion of a Specific Poll addressed to the responsing device, a device selection addressed
to any other device on the same control unit, or a General Poll addressed to the same control unit, is required to restart the internal
control unit device polling operation.

If any of the conditions cited in Note 3 prevail, the EOT response takes precedence over the WACK response.

to Receive SIS Bytes
Read
- - - - - - t - - - - - - - - + - - (Interrupt: CE + DE) -+-------~

Start 1/0

D No text is transmitted on an EAU command transmission.
II Command transmission was not successfully received because of invalid framing (STX missing). Causes a timeout TCU.
II The control unit is unable to perform the operation indicated in the command transmission because of a busy/unavailable/not ready

Start I/O
I

Notes:

TCU Read Data
(Generated by 3274)

I
Start I/O, - - - Write (CC) -

5-16

]

Command Code and
next block of text

I....-~----+.---Write---~---EOT
(Terminate) I

Figure 5-32. Write-Type and Control-Type Commands, Sequence/Response Diagram

I/O Supervisor/
Access Method

CCW

Notes:

TCU Read Data
(Generated by 3274)

TCU Write Data
(From Channel Program)

. . Command transmission was not successfully received because of invalid framing (STX missing). Causes timeout at TCU.

fJ The 3274 is unable to perform the operation indicated in the command transmission because of a busy/unavailable/not ready

device or a 3274 detected check condition (receipt of an illegal command/order sequence, failure to decode a valid command, or
an I/O interface "overrun"). The EOT response to a command transmission indicates that status information is stored in the 3274.
To ensure retrieval of valid status, a Specific Poll must be issued to the device-responding EOT as the next addressing sequence
issued to this 3274.

(Selection Sequence or
Previous Command Op)

Startl!O -

III If a transmission problem causes both a 3274-detected check condition and a BCC error, the BCC error takes precedence over all

. . . . Write eCC) - - - . STX
ESC
Command Code
ETX
(BCC) Hardware
Read
• Generated

other check conditions, and a NAK is transmitted to the TeU.

II Response issued by the program to terminate the operation if the 3274 is unsuccessful in receiving a valid BCC following "n" attempts
by the program to transmit the message.

II This address sequence is included only in the first block of a blocked text message.

.
~o

II Upon detection of an internal parity check. the 3274 automatically substitutes the SUB character for the character in error.

EOT

I Response
.......---_--------~ (Interrupt: CE + DE + UC)
(TCU Sense Bit: Timeout)

ETB is used to frame each block of a blocked text message, except for the last block. ETX is used to frame the last block of a blocked
text message.
If a
parity or cursor is detected, ENQ is transmitted in place of ETX (or ETB) and BeC at the end of the text block and appropriate status
and sense information is stored. This is used by the 3274 if, after the first block has been transmitted, the transmission cannot be completed because of power being off at the terminal .

NAK

I-----'

II Mandatory program response to a text block terminated in ENQ.
iii Response to terminate the operation. The nature of the error (parity or cursor check) does not warrant a retry. This response indicates

lID BCC error has been detected.

-----"I4--------------+--(lnterrupt: CE + DE)-.......
Start I/O

------4~-- Write

..,1

----t----- EOT II

that appropriate status and sense information is stored. The status retrieval information included in Note 2 applies.

r- ---

I-------

r-t----+--------t--(Interrupt: CE + DE + UE) ........

r----.J

Start I/O

--,

Write (CC) --....--rSpecific Poll SequencEil
Lto Receive SIS Bytes
Read

I
I

~[
.:.

SUB}

I Text

STX
3274 Poll Adr
Device Adr
Text
ETX or ETB
BCC

ENQ

I
L ________ _

(Interrupt: CE + DE)

I
Start I/O

1....---~- Writj (CC)

I
I

The program issues NAK to cause the 3274 to repeat its last transmission.

Positive acknowledgment. The text block has been successfully received by the TCU. The program issues ACK 1 in response to the first
and a" odd-numbered text blocks and issues ACK 0 in response to the second and all even-numbered text blocks. This response to a text
block terminated in ETX turns on the device SYSTEM AVAI lABlE indicator.

The second and all succeeding text blocks are framed as the first except that they do not include the 3274/device address sequence.

III Normal termination of the operation following transmission of the last text block.
lEGEND:
(CC) = Chain Command (CC) Flag in CCW is set to 1.

(Interrupt) = TCU-generated interrupt (CE = Channel End, DE = Device End, UE = Unit Exception, UC = Unit Check)

-1

----t--- NAK 11---.......-----.1

Read

EOT

. , - - -...- - - - - -..... (Interrupt: CE + DE;
also + UC if BCC error) :
Start I/O
(TCU Sense Bit: Data Check)
(BCC Error)
I
_.---+-..--Write (CC)--t---- NAK IID----~

,------------

I .

I
I

Read

Write-----,,...----EOTII

...--_-Write eCC) -

...-ACK 1 or 0

Read

Next text
block

EOTIIJ

Figure 5-33. Read-Type Command, Sequence/Response Diagram

SY27-2512-3 :

.5-17

SY27·2512·3
5.8 REMOTE STATUS AND SENSE BYTE
DEFINITIONS, MODEL C, BSe
Figures 5-34 through 5-36 provide status and sense byte
definitions, responses, conditions, and error recovery procedures for the 3274 Model e, BSe.

Bit

No.

Bit Definition
SIS Byte 0:

Dependent upon setting of bits 2-7.

Always a 1.

Reserved.

Device Busy (DB) - This' bit indicates that the addressed device (except the 3278) is busy executing an operation or that a busy

detection was previously made by a command or Specific Poll. The device is busy when it is executing an Erase All Unprotected
command or a print operation, accepting data from the Operator Identification Card Reader, or performing various keyboard
operations (Erase Input, Backtab, and Clear).
This bit is set with Operation Check when a Copy command is received which specifies a "busy" device with its "from"
address.
This bit is set with Unit Specify when a command is addressed to a busy device. This can occur by chaining a command to a
Write, Erase/Write, Erase/Write Alternate, or Copy command which started a Printer or by chaining a command to a Specific
Poll addressed to a busy device.
Note: DB is not returned for the 3278 when executing an Erase All Unprotected command, accepting data from ttle MSR, or
performing Erase Input, Backtab, or Clear keyboard operations.
5

Unit Specify (US) - This bit is set if any SIS bit is set as a result of a device-detected error or if a command is addressed to a

Device End (DE) - This bit indicates that the addressed device has changed from unavailable to available and not ready to ready,

busy device.
or busy to not busy. This bit is included during a Specific or General Poll but is not considered pending status by a Selection
Addressing sequence.
If a Selection Addressing sequence detects that the addressed device has pending status and also detects one of the above status
changes that warrants a Device End, then the Device End bit is set and preserved along with the other pending status, and an RVI
response is made.
7

Transmission Check (TC) - Not used by the 3274.

SIS Byte 1:

Dependent upon setting of bits 2-7.

Always a 1.

Command Reject fCR) - This bit is set upon receipt of an invalid 3270 command.

Intervention Required fiR) - This bit is set if:

•

A Copy command contains a "from" address in its data stream which specifies an unavailable device.

•

A command attempted to start a printer but found it not ready. The printout is suppressed.

•

The 3274 receives a Selection Addressing Sequence or a Specific Poll sequence for a device which is unavailable or which
became not ready during a printout. A General Poll sequence does not respond to the unavailable/not ready indication and
proceeds to determine the state of the next device.

•

The 3274 receives a command for a device which has been logged as unavailable or not ready.

Equipment Check (EC) - This bit indicates a printer character generator or sync check error occurred, the printer became

mechanically disabled, or a 3274-detected bad parity from the device.
5

Data Check (DC) - This bit indicates the detection of a parity check in a device buffer or a 3274 operation to a device was

unsuccessful O.e., the device was disabled with DC returned to the host; IR will be returned on subsequent retry by the host).
6
7

Control Check (CC) - This bit is not used by the 3274.
Operation Check (OC) - This bit, when set alone, indicates one of the following:

•

Receipt of an illegal buffer address or of an incomplete order sequence on a Write, Erase/Write, or Erase/Write Alternate
command.

•

The device did not receive a CCC or a "from" address on a Copy command.

•

Receipt of an invalid command sequence. (ESC is not received in the second data character pOSition of the sequence.)

•

An I/O interface "overrun". This occurs if the internal buffering capability is exceeded.
This bit is set with Control Check, Intervention Required, Data Check, Device Busy, or Data Check with Unit Specify
to indicate that the errors that set these sense bits were detected while the 3271 was executing an operation with the "from"
device during a Copy command. This bit is set with Unit Specify to indicate that the "from" address on a Copy command
specified a device with a "locked" buffer (the device data is secure).

Figure 5-34. Remote Status and Sense Byte Definitions, BSe

5·18

Device
Response

Command

SIS Explanation

RVI

Selection

Outstanding Status - Pending information from a previous operation with the same device. (If the addressed
device is busy, WACK is sent to the TCU instead of RVI, and no SIS bit is set.! Note: A Selection Addressing
sequence does not recognize a Device End as pending status. If there is no other pending status, it resets this
bit and proceeds with the selection. If the addressed device has other pending status, Device End remains set
with it, and the RVI response is made as usual.

EaT

Command
Copy
Command

OC, US - The "from" device has a locked buffer.

IR .:.... The addressed device is unavailable.
DC, EC (either or both) - Not used for the 3274.

OC - The data stream contains other than twO bytes (the CCC and the "from" address!. The command is
aborted.

DE, EC, US - A character generator or syn check error has occurred, or the printer was mechanically disabled
but the condition has been corrected. DE, EC, US is not sent by the 3287 or 3289.

DC, OC - Not used for the 3274.

DE, IR, EC, US - The addressed printer is mechanically disabled and cannot recover.

DC, OC, US - Set when "from" device detects an internal parity or cursor check. An operation to a terminal
was unsuccessful. The terminal was disabled and DC US returned to the host. On subsequent retry by the
host, IR will be returned to the host.

DE, DC, US - A parity error is detected at the printer.

DB, US - The addressed "to" device is busy.

DC, US - An operation to a terminal was unsuccessful. The terminal was disabled and DC US returned to the
host. On Subsequent retry by the host, IR will be returned to the host.

DB, US, OC - The addressed "to" device is also specified as the "from" device and is busy.

DE, IR - The addressed printer is out of paper, its power has been turned off, or its cover is open.

Read
Commands

DB, US, OC, DE - The addressed device becomes not busy before a specific poll is issued to retrieve the DB,
US, OC status (described above).

CR - Invalid 3270 command is received.
EOT

OC - Invalid command sequence (ESC is not in the second data character position), or data follows the
command in the data stream received at the device.
DB, US - The addressed device is busy. The command was chained to a Write, Erase/Write, Erase/Write
Alternate, or Copy command which started a print, or it was chained to a Specific Poll.
DB, US, DE - Not used for the 3274.
IR - A command is addressed to an unavailable device.

EaT

DC - The 3274 is unable to complete a Read command operation after the first block has been sent to the
host, because either there was an error in the terminal or the terminal was powered off after the first block
was sent. A SUB character and an ENQ character are placed in the buffer. When the TCU responds NAK,
the 3274 responds EaT.
DC, US - An operation to a terminal was unsuccessful. The terminal was disabled and DC US returned to
the host. On subsequent retry by the host, IR will be returned to the host.
EaT

Write
Commands

CC, OC - Not used for the 3274.
DB, OC - The "from" device is busy. (The device is busy executing an operation, a printout, reading data
from the Operator Identification Card Reader, or performing a keyboard operation.! The Copy command is
aborted.
IR, OC - The "from" device is not available.

CC - Not used for the 3274.

EaT

SIS Explanation

Write,
Erase/Write,
Erase/Write
Alternate,
Copy
Commands

IR - Addressed device is not available, or addressed printer is not ready.

Erase All
Unprotected
Command

OC - One or more data bytes followed the command (buffer overrun).

Specific
and
General
Poll

DE, IR, EC, US - An unrecoverable mechanical failure is detected at the printer.

DC - The 3274 is unable to complete a Read command operation after the first block has been sent to
. the host, because either there was an error in the terminal or the terminal was powered off after the first
block was sent. A SUB character and an ENQ character are placed in the buffer. When the TCU responds
NAK, the 3274 responds EOT.

OC - An invalid command sequence (ESC is not in the second data position), an illegal buffer address or an
incomplete order sequence is received, or a data byte was sent to the device during the Write command
before the operation required by the previous data byte was completed.
DC - Not used for the 3274.

DC, EC (either or both) - Not used by tlie '3274.

DC, US - An operation to a terminal was unsuccessful. The terminal was disabled and DC US returned to the
host. On subsequent r' ... , by the host, IR will be returned to the host.
~

DE, EC, US - A character generator or sync check error or a mechanical failure is detected at a 3284/
3286/3288 printer but then recovered from.
DC, US - An operation to a terminal was unsuccessful. The terminal was disabled and DC US returned to the
host. On subsequent retry by the host, IR will be returned to the host.

CR - An invalid or illegal 3270 command is received.

CC - Not used for the

IR, EC, US - Not used for the 3274.

DE - The poll finds a device (1), previously recorded as busy, now not busy or, (2). previously recorded
as unavailable or not ready, now available and ready.

_74.

IR, DE - The poll finds a device, previously recorded as ready, available, and busy, now not ready and
not busy, or the printer went not ready duting a printout.

DB, US - The addressed device is busy. The message is accepted but not stored in the 3274 buffer. The
command is aborted.

DC, US, DE - A parity error is detected at printer.

DE, DB, US - Not used for the 3274.

CC (Specific Poll only) - Not used by the 3274.

Figure 5-35. Remote Error Status and Sense Responses, BSe
NAK

SY27 -2512-3

Specific
Poll

CC - Not used by the 3274.

Read and
Write
Commands

NAK is transmitted by the 3274 when it detects a Block Control Character (BCC) error on the TCU
transmission. A BCe error has priority over all other detectable error conditions. If, for example, a BCC
error and a parity error are detected during the same command transmission, the parity error condition
is reset, and a NAK response is set by the 3274.

DB - The addressed device is busy.

5-19

SY27 -2512-3

~~
Detected during 3270 Operation

Sensei

Hex

Status
Bits

~.,

CR
OC

II1II

•

OC, US
IR
IR,OC
DC
DC, US
DC,OC,US
DC, US, DE
EC, US, DE
IR,EC,US,DE
DB
DB, US*
OC,DB*
IR,EC,US

~~
~
~
~
~.

EBCDIC

ASCII

40
40
C4
40
40
40
C4
C4
C6
C6
C6
C8
4C
C8
C4

20 20
20 41
44 41
20 26
204A
20 44
44 44
44 45
46 44
46 48
46 51
48 20
3C 20
48 41
44 51

60
C1
C1
50
D1
C4
C4
C5
C4
C8
D8
40
40
C1
D8

Selection
Addressing
Sequence

Specific
Poll
Sequence

0, P

D, P

D,P
D,P

D, P
D, P

General
Poll
Sequence

3270
Command

D,P

D, P
D,P
D, P
D,P
D,P
D, P

D, P

~
•
-.,

D,P

P
P
P

D,P
D,P
P

3274

D, P

0, P

D, P

~' P

~.P

Error
Recovery
Procedure

0, P
0, P

~ ~::
,

_
..
..

General
Poll"

D,P

D, P

Specific
Poll
0, P

~, ~: ~

D,P

P
P
P

Tra'!smitted
in Response
to:

6
6
13
4

5
1
2
3
8

~ ~.r
~ ~!

Note: The attached device errors that are detected asynchronously do not cause a Sense bit to set until the device is polled for status during a
Selection Addressing, Specific Poll, or General Poll sequence. Those error SIS bit combinations that contain DE were detected during a printout.
*~he D~, U~, and OC

SIS bits will be combined if a Copy command is addressed to a busy "to" device and the command also specifies the
from devIce the same as the "to" device.
tOccurs only if 3284, 3286, 3288 Printers are attached.
Legend
NA
D
P

5.B.1 Error Recovery Procedures, Model C, BSe
1. Execute a new address selection addressing sequence
and retransmit the message, starting with the command
sequence that was being executed when the error
occurred. If, after two retries, the operation is not
successful, this should be considered as a nonrecoverable error. Follow supplementary procedure B after
two retries.
2. Reconstruct the entire device buffer if possible, and
retry the failing chain of commands (within the BSC
sequence of operations). The sequence of commands
used to reconstruct ~he buffer should start with an
EraseIWrite or Erase/Write Alternate command. If the
information in the screen buffer is such that it cannot,
or need not, be reconstructed, the operation may still
be retried. If an unrecoverable 3278 buffer error or an
error occurring on a transfer between the 3276 and
3278 is detected, the entire buffer is cleared and the
host system is informed of the error by receiving DC,
US status but is not informed of the clear operation.
If, after three retries, the operation is not successful,
this should be considered as a nonrecoverable error.
Follow supplementary procedure A.
Programming Note: A cursor check in the 3284 is indistinguishable from a data check that occurred in the 3271 or
from a second selection to a 3277 with a cursor check. A
selection addressing sequence or poll sequence to another
device on the same control unit should be attempted before
flagging the control unit as inoperative. A successful
sequence indicates that the CU is probably satisfactory, and
the device requires manual intervention to reset it (for
example, a 3277 with a nonrecoverable data check). An
unsuccessful sequence indicates that the CU may be at
fault and requires manual intervention to reset it.

Not Applicable
Display (3277,3278)
Printer

Figure 5-36. Remote 3270 SSC Status and Sense Conditions

3. The error occurred during execution of a Copy command. Execute procedure 2, except that it is the buffer of the "from" device specified by the Copy command that should be reconstructed. After three retries,
follow supplementary procedure B.
4. The error indicates that the printer is out of paper, has
its cover open, or has a disabled print mechanism; or it
indicates that the device is unavailable. Request (or
wait for) either the display or system operator to
ready the device. Then, retry the printout by issuing a
Write command with the proper wec and no data
stream. (There is no data error, and the data is still
intact in the device buffer and can be reused.) Or,
follow procedure 2.

5-20
5. The error indicates that the "from" device specified by
a Copy command is unavailable. Note that the device
address associated with the error status and sense information does not indicate the device that actually
required "readying." The device that requires the
corrective action is the device specified by the "from"
address in the Copy command. When the device is
determined and made "ready," follow procedure 1.
6. The operation should be tried up to six times. Continued failure implies an application programming problem, whic!l can be detected by analyzing the failing
write data stream.
7. The error occurred during a printout operation and
indicates either a character·generator error or a disabled
print mechanism. There is no data error. The proper
error recovery procedure is application-dependent
since the user mayor may not want a new printout. If
a new printout is required, follow procedure 4.
8. A data error occurred in the device buffer during a
printout, and procedure 2 should be followed.
9. A Specific Poll detected that the addressed device is
busy. Periodically issue a Specific Poll to pick up the
Device End sense/status bit sent by the device when it
becomes not-ready (unless this status change is detected
on a selection addressing sequence).
10. Indicates that a command was erroneously addressed to
a busy device. Periodically issue a General or Specific
Poll to pick up the Device End sense/status bit sent by
the device when it becomes not busy. Then follow
proced ure 1.
11. Indicates that, in attempting to execute a Copy command, the "from" device was found to be busy.
Follow procedure 1 when the "from" device becomes
not busy. Note that the device address associated with
the status and sense message is the address of the "to"
device and not that of the busy "from" device. The
"from" device will transmit Device End via a Specific
or General Poll when it becomes not busy.
12. Indicates that the 3275 detected a BCC error during
text transmission from the TCU. Follow procedure 2
if the failing command is a Write command with a
data stream of more than one byte or if it is in a chain
of commands and one of the previous commands in
the chain is a Write command without an SBA order
immediately following the WCC character. In all other
cases, follow supplementary procedure D. If, after the
recommended procedure has been tried six times, the
problem is not corrected, follow supplementary procedure A.
13. An attempt was made to execute a Copy command, but
access to the "from" device data was not authorized.
The device address associated with the error sense/status
bits is that of the Copy "to" device.

5.8.2 Supplementary Procedures
A. Request maintenance for the device that is giVing trouble. After repair, reconstruct the screen buffer image.
The sequence of commands used to reconstruct this
image should start with an Erase/Write command.
Retry the failing chain of commands according to the
procedure that referred you to this supplementary
procedure.
B. The "from" device specified by the Copy command in
the failing chain of commands (CCWs) is malfunctioning. The "from" device should be determined from the
data-stream information; and maintenance should be
requested for the device. After the repair, reconstruct
the buffer image. The sequence of commands used to
reconstruct this image should start with an EraselWrite
command. Retry the failing chain of commands
according to the procedure that referred you to this
supplementary procedure.
C. Same as procedure 1, except a new selection addressing
sequence is not performed, and this message is transmitted as part of the present device selection.
D. Same as procedure 1, except retransmit the entire failing chain of commands.

5.9 MODEL A, LOCAL ATTACHMENT
(SNA VERSION)
The following information is given for the 3274 Model A:
• Commands
• Status and sense byte definitions

5.9.1. 1 Write Command

5.9.1.5 Control Command

The Write command requests data transfer from the host. A
minimum of four bytes, called the data count field, must be
transmitted in a specific format:

The Control command provides two functions to the 3274
Model A: Connect and Disconnect

•

Bytes 0 and 1 must contain the total byte count of the
record that is being transferred.

•

Bytes 2 and 3 are undefined and not used.

5.9.1.5.1 Connect Function: The host Physical Unit
Services issues a Control command (05) to send initialization
parameters to the Model A.
The data stream consists of the following 10 bytes:

• SNA data

Byte

5.9.1.2 Read Command

Content

The Read command requests data transfer to the host. The
format of the data is:
•

0
1

1
1

11 = 'OOOA'X
Reserved = 'OO'X
Function Code = '01'X
Number of Host Buffers

Link Header* consisting of:
Data count field (four bytes)
Pad characters (n bytes)
*The size of the link header is determined by the connect.
(See 5.9.1.5.)

Size of Host Buffers

• SNA data

5.9.1.3 No Operation Command
This command does not transfer data. Ending status to
this command does not reflect any change within the 3274
Model A. Normal System/370 use inserts NOP in a CCW
string for possible later dynamic program modification, or
as a stand-alone command for checking availability of the
channel path to the control unit. In addition, the NOP
command may be used as the ending command in the Read
CCW, Write CCW, and Write-Read CCW sequences.

• Error-recovery procedures

Secondary to Primary
Link Header Size

2
RSVD

3
FUNC
CODE

No. of Host
Bu~fers

Size of Host
Butfers

Sop Link
He~der

Total number of bytes
Not used
CONNECT function code
The number of buffers contained in each host Read channel program. Used to determine the maximum number of
basic transmission units (BTUsl that the 3274 Model A
may send to the host with each Start I/O command.
The total number of bytes the 3274 Model A may send
with each Read CCW. The total length is the sum of the
path information unit and S to P link header, including
pad characters.
Specifies the total length of the Sop link header. This
length consists of the 4-byte fixed portion of the link
header plus "n" pad characters. All S to P PIUs are
preceded by 4+n bytes.

The 3274 Model A determines that these parameters
are acceptable when the size of the host buffer is large
enough to accommodate the link header (LH), the pad, the
transmission header (TH), the request header (RH)' and at
least 64 bytes of data (R U), and the host buffer is an even
number of bytes.'

5.9.1.4 Sense Command
5.9.1 Commands
Figure 5-37 gives the 3274 Model A command codes.
Command

Code

Write

Read

NOP

Sense

Control

Write Break

Write Start 0

Read Start 0

Write Start 1

Read Start 1

Restart Reset

Sense ID

This command is normally issued after unit-check status has
been presented to the host, and requests 2 bytes of sense
data. The sense bits are predictable and meaningful only
after presentation of unit-check status. The sense bits are
retained for possible re-reading until a command other than
Sense or NOP is accepted.

Rejection of the CONNECT function code will be a status
of DE, UC, and Sense NI (not initialized) to the next
command received by the control unit. Command Reject
(CR) may also be set according to the type of command
received.
Receipt of a Connect Function code while already connected will cause the 3274 Model A to reset the physical unit to active. A new ACTPU sequence is required.

Figure 5·31. 3214 Model A Local
Command Codes

SY27 -2512-3

5-21

5-22

SY27-2512-3

5.9. 1.5.2 Disconnect Function: The host Physical

5.9.1.9 Write Start 1 Command

5.9.2 Status and Sense Definitions

5.9.2.1 Status Bits

Unit Services issues a Control command (05) that sends to
the 3274 Model A control unit a disconnect function. The
NI sense bit will be set.

This command is similar to the Write Start 0 command. It
attempts to change the Write Start indicator from the alternate setting of the Write Start 0 command. In other
respects the two commands are the same.

Figures 5-38 and 5-39 define the status and sense bits,
respectively.

Figure 5-40 describes the status bit conditions.

The contents of the 4-byte data stream are:
Byte

Content

Reserved

Function
Code

11 = '0004'X
Reserved = 'OO'X
Function Code = '02'X

Total number of bytes
Not used
Disconnect function code

*The data stream can be larger than 4 bytes, but only 4 bytes are
used and the rest are ignored. The number of bytes sent n1ust
agree with the length in the data count field.

5.9.1.6 Write Break Command
This command must be used as the last Write command in
all Write CCW sequen~es. If only one write CCW is to be
issued, it must be the Write Break command. This command includes all the functions shown for the Write
command.

5.9.1.7 Write Start 0 Command
All data from the host is sent bya Write CCW sequence. A
Write Start command initializes the sequence. No data is
transferred for this command. It attempts to set the Write
Start indicator, which is used as a reference for data sent
from the host.
All data from the host in a chained command CCW string
is under the envelope of a preceding Write Start 0 command. The data is considered valid, that is, no need for
retransm ission, when the control unit receives a Write
Start 1 command. "New" data is transmitted only when
the Write Start 1 command is accepted by the control unit.
Note that new data is transmitted when a Restart Reset
immediately precedes a Write Start O. The Write Start command attempts to change the Write Start indicator state.
The indicator is not changed if the command is not accepted,
or Unit Exception (UE) is part of the ending status.

5.9.1.8 Read Start 0 Command
All data is received by the host via a Read CCW sequence,
which is initialized by a Read Start command. This
sequence will be considered fully completed by the 3274
Model A upon receipt of a subsequent alternate Read
Start command~ New data is transmitted when a Restart
Reset command immediately precedes a Read Start 0 command. No data is transferred for this command.

Note that "old" data is retransmitted when a Restart
Reset command immediately precedes a Write Start 1
command.

5.9.1.10 Read Start 1 Command

Bit

Name

0
1
2

A
SM
CUE
B
CE
DE
UC
UE

3
4
5

6
7

This command complements the Read Start 0 command.

Attention
Status Modifier
Control Unit End
Busy
Channel End
Device End
Unit Chec'k
Unit Exception

Name

Condition

Indicates an inbound message has been readied by the
3274 Model A for transmission to the host. The
host should respond by issuing a Read CCW
sequence.

I ndicates to the host that the control unit is ready
to receive data from the host or set in response to
Write Break command, as a request for a Read. Also
set with Busy (see below) when control unit is busy.

CUE

Is set following a busy condition, after pending
status is cleared or when control unit is no longer
busy, to indicate that 3274 Model A is now not
busy and is free to accept a new command.

Is set in initial status byte with the status modifier
(SM) when the addressed 3274 Model A is busy.
The 3274 Model A uses this sequence when it
cannot respond to the normal channel initiated
selection sequence. See CUE above for the reset
of the busy state.

Indicates channel data transfer operations are
completed. No error unless Unit Check (Uel is
included.

Indicates that the control unit is ready to receive a
new command.

Is set when an irregular program or equipment
condition is detected by 3274 or the device. The
program should always respond to Unit Check
status by issuing a Sense command for further
definition of condition.

Indicates that no data is available for a successive
(following) read.

Figure 5-38. Status Definitions
Previous (old) data is retransmitted when this command
follows a Restart Reset command.

5.9.1.11 Restart Reset Command
Data is not transferred with this command. Restart Reset
is used to reset the 3274 Model Read Start and Write
Start indicators to logical zero. Previously transmitted data
is subject to retry if the Restart Reset command is followed
by a Read Start 1 command or a Write Start 1 command.
(That is,improper usage may result in duplicate or lost
data.) Ending status does not reflect the inability of the
3274 Model A to transfer data to/from the control unit.

5.9.1.12 Sense ID Command
This command requests data transfer to the host. Four
bytes of data are sent as follows:
Byte 0 - FF
Byte 1,2 -'3274
Byte 3 - Model A
The Sense 10 command is honored when the 3274 Model
A is in the following state:
Power on
IML completed
Online
Not busy
No outstanding status to be presented

Bit

Name

CR
IR
BOC
EC
DC
NI

OLC
DR

1
2
3
4
5

9
10
11
12
13
14
15

PCM
PC1
PC2
MC

Command Reject
Intervention Required (not used)
Bus Out Check
Equipment Check
Data Check
(not used)
Not Initialized
(not used)
Data Length Check
Data Reject (not used)
(not used)
(not used)
Parity Check Modifier
Parity Check 1
Parity Check 2
Controller Machine Check

Figure 5-39. Sense Definitions

Figure 5-40. Status Bit Conditions

•

5.9.2.2 Sense Bits
Figure 5-41 describes the sense bit conditions.
Name

Condition

Set if the 3274 Model A has received an invalid
command. It is also set if the Not I nitialized bit is
set and a Restart Reset, Read Start 0/1 , Write
Start 0/1, Read, Write, or Write Break command is
received.

Not used.

BOC

Set if the 3274 Model A has detected bad parity
on any command or data byte received from the
channel.

-EC

DLC

Set in response to any command if a control unit
parity check has occurred, or if a control unit I/O
error has been detected during a Control, Read,
Write, or Write Break command.
Set in response to a Control, Write, or Write Break
command along with data length check (OLC)
(refer to DLC) or a Read command if the byte
count specified in the host's Read command was
not large enough to transfer all data associated with
the control-unit buffer.
Set when the 3274 Model A has not been initialized
via an acceptable Connect function via a Control
command.
_ Set in response to a Control, Write, or Write Break
command if less than 4 bytes have not been transferred as the data count field or the count in the
data count field does not equal the total byte
count received.

PCM

See Ending Status and Sense Conditions below.

PC1

See Ending Status and Sense Conditions below.

PC2

See Ending Status and Sense Conditions below.

Set with Equipment Check to indicate that an
error occurred during cycle steal operations.

Figure 5-41. Sense Bit Conditions

5.9.2.2.1 Initial Status:

Initial status is generated by
the 327'4 Model A in response to initial selection, by the
channel, of the 3274 Model A. During the initial selection
sequence, the status byte is sent to the channel after the
3274 Model A receives a command.

Status
(hex)

Figure 5-42 shows the possible initial status bit
configurations.

Sense
(hex)

ERP2

CE
(08)
CE, DEI
(OC)

Sent at end of data stream on all valid commands except Control, Write, Read, and
Write Break.

CE, DE, UE I
(00)

Sent in response to:
1. A Control, Write, Write Break, or Write Start 0/1 command because of insufficient buffer space in the 3274 Model A at the time of the request. The command and its associated data transfer (if any) are rejected.
2. Read command if there is no new data available at this time for a subsequent
Read in this CCW sequence. All available data has been transferred to the host.
3. Read Start 0/1 command if there is no data available for transfer to the host in
response to th is request.

An all-zero status byte is sent when a command is accepted
for execution by the control unit.
Status l

Sense

ERP2

All
Zeros
- B,SM

Condition
Normal status for all commands.

CE, DE, UE, Al
(80)

Sent in response to:
1. A ContrOl, Write, Write Break, or Write Start 0/1 command because of insufficient buffer space in the 3274 Model A at the time of the request. The command and its associated data transfer, if any, are rejected. In addition, a Read
CCW sequence is requested.
2. Read Start 0/1 command as a warning. Its purpose is to notify the host that
an unsolicited Read CCW sequence was issued. The command was rejected.
However, data is available for transmission to the host.
3. Read command that all data for a block has been transmitted to the host,
and therefore, a new Read CCW sequence is requested. Note that a new Read
CCW sequence is necessary to release the 3274 Model A buffers for reuse.

Response to a command
addressed to a 3274 Model A
when the control unit cannot
respond to a normal channel
initiated selection sequence.

llf a Start 1/0 Fast Release (SIOF) is executed by the channel,
unchained initial status becomes ending status.
2See paragraph 5.6.2.

Figure 5-42. Initial Status and Sense Conditions, 3274
Model A

5.9.2.2.2 Ending Status.·

When the control unit completes channel operations for a command, it sends an
ending status byte to the channel, freeing the channel for
other operations. This status byte always relates to the
command operation that has been executed. The normal
ending status byte for a read-type command or sense-type
command will have only the channel-end and device-end
bits set, indicating that the command has been executed.
Normal ending status for a write-type command is channelend alone. When the control unit-to-device buffer transfer
is completed, ending the command operation, Device End
status is sent to the channel as asynchronous status. Any
error condition associated with the operation just executed
will cause additional status bits to be set. Figure 5-43
shows the possible ending status bit configurations. Ending status causes an I/O interruption unless chaining is
specified.
When the control unit has pending status, it attempts to
gain selection of the channel asynchronously to pass this
status. It is passed to the channel either when selection is
accomplished or as initial status for the next command
(with the Busy bit set), whichever occurs first.

Condition
Sent at end of data stream on a Control, Write, or Write Break command.

CE,OE,UC
(OE)

CR,NI
(8200)

Send in response to a Restart Reset, Read Start 0/1, Write Start 0/1, Read, Write,
or Write Break command if the 3274 Model A is not initialized.

CE,OE,UC
(OE)

CR
(8000)

An invalid command was issued to the 3274 Model A.

CE,OE,UC
(OE)

NI
(0200)

Sent in response to a NOP or Sense I D command if the 3274 Model A is not
initialized.

CE,OE,UC
(OE)

BOC, PC2
(2002)

The 3274 Model A detected a parity error at command time or on data transfer
from the host.

CE,OE,UC
(OE)

BOC, PC1 , PC2
(2006)

The 3274 Model A detected a channel parity error during a Write command.

CE,OE,UC
(OE)

EC, PC1
(1004)

The 3274 Model A detected a control unit parity error during a Write command.

CE,OE,UC
(OE)

EC, PC1, PCM
(100C)

The 3274 Model A detected a control unit parity error during a Read command.

CE,OE,UC
(OE)

EC, PC2
(1002)

The 3274 Model A detected a channel parity error during a Read command.

CE,DE,UC
(DE)

EC, MC
(1001 )

The 3274 Model A detected a cycle steal operation error during a Write or Read
command.

CE,OE,UC
(OE)

DC
(0800)

The byte count specified in the host's Read command was not large enough to

CE,OE,UC
(OE)

OC,OLC
(0880)

Set in response to a Control, Write, or Write Break command if a minimum of 4
bytes have not been transferred or if the count in the data count field did not
equal the total byte count received.

transfer all data associated with the 3274 Model A buffer.

llf this status is stacked by the channel, CUE could be generated and combined with it before the stacked status is accepted by the channel.
2See paragraph 5.6.2.

Figure 5-43. Ending Status and Sense Conditions, 3274 Model A

SY27-2512-3

5-23

SY27-2512-3

5.9.2.2.3 Asynchronous Status: Asynchronous
status reflects that (1) this is the second ending status for
a Control, Read, Write, and Write Break command, indicating that all command-initiated operations are completed,
(2) this is a request for the host to initiate a' Read CCW
sequence, (3) the 3274 Model A now has buffers available
for a Write CCW sequence, or (4) the 3274 Model A is
initialized or not initialized. Figure 5-44 shows the possible
asynchronous status conditions.
Status

Sense

ERP2

The 3274 Model A requests
the host to initiate a Read
CCW sequence.

The 3274 Model A is ready to
communicate with the host.
In the case of a Control, Read,
Write, and Write Break command this is normal ending
status. For Control, Write, or
Write Break, all data associated
with the command has been
transferred; transfer was terminated by the channel. For
Read, all data available for
this command has been transferred. However, more data
is available for a subsequent
Read. For a NOP command
at the end of a Read CCW
sequence, this is a special
case and if th is is seen by the
host indicates incompatibility
between the host and the
3274 Model A. The number of Read CCWs in the host
is less than the number expected
by the 3274 Model A as a
result of the Connect function.

Indicates that the 3274 Model
A requires a, Read CCW
sequence.

DE,SM,
A
DE,UC

Condition

The 3274 Model A has successfully enabled the interface to
the host and the not-initialized
bit is on.

llf this status is stacked by the channel, CU could be generated and
combined with it before the stacked status is accepted by the
channel.
2 See paragraph 5.6.2.

Figure 5-44. Asynchronous Status and Sense Conditions,
3274 Model A

When an asynchronous status condition occurs, the con·
trol unit attempts to gain selection by the channel and
passes this status to the channel when selection is accomplished. This status is called "pending" status until selection is accomplished. If the channel issues a command
before retrieving this pending status, the pending status is
returned, with the Busy bit set, in place of initial status
for the command; in this case, the command is not
executed.
Other conditions of multiple status can occur that are
not covered here. These conditions can be caused by multiple error conditions occurring simultaneously.

5.9.3 Error Recovery Procedures
5.9.3.1 Model-A-Detected Errors
Error conditions detected by the 3274 Model A are indicated to the program by Unit Check status. The program
must respond to this status by using a Sense command for
further definition of the condition. If a Sense command is
not performed and the sense conditions still exist, the 3274
Model A wili not honor any other commands.
Device-detected errors are reported via SNA.
The recovery procedures referred to in the Error Recovery
Procedure (ERP) column of Figures 5-42,5-43, and 5-44
are as follows:
1. Issue a message containing the address of the channel and
unit, the CSW, the sense data, and the CCW executed. If
the first CCW of the chain is a valid Start command,
begin retry from that point. If the failure is continuous,
notify the operator.
2. A nonrecoverable program error has occurred. Examine
the data stream to locate the problem.
3. No retry possible. Issue a message as in 1 above, and
notify the operator.
4. An initializing control command is needed.

5.9.3.2 Channel-Detected Errors
Errors detected by the channel are indicated to the program
by the channel status byte in the CSW. If the channel status
byte indicates a channel control check, an interface control
check, or a channel data check, the recommended errorrecovery procedure is to retry the chain of commands. If
the channel status byte indicates a channel program check,
a protection check, or an incorrect length (should not
occur), the recommended error-recovery procedure is to
terminate the task. A program error has probably occurred.

5-24

5-10 SDLC SEQUENCE/RESPONSE
DESCRIPTIONS
5.10.1 SDLC Transmission Frames
SDLC transmission frames are composed of a series of eightbit binary-coded bytes which contain addressing, data, control, and checking information. Transmission between the
controller and the 3274 unit takes place according to a
predefined frame format which consists of the following
sequence of bytes:
Flag (F) Sequence - 1 byte
Secondary Station Address (A) - 1 byte
Control (C) Field - 1 byte
Information (I) Field - up to 256 bytes of message
data, preceded by header information
Frame Check Sequence (FCS) - 2 bytes
Flag (F) Sequence - 1 byte
Bit synchronization preceding transmission of an initial
flag and following a line turnaround is achieved by transmission of 16 zero bits, after the clear-to-send signal is
turned on and the NRZI encoder (when used) is enabled.

When in NDM, the 3274 cannot accept or transmit I or
supervisory (S) frames. Nonsequenced responses are not
transmitted unless the 3274 is solicited to reply. Invalid
or nonimplemented commands received in NDM cause
the 3274 to transmit an ROL response at the next response
opportunity. ROL can be retransmitted until an SNRM or
DISC command is received. Command reject conditions are
not present in NDM.
The following paragraphs describe the 3274 support of the
Control and Information fields.

5. 10. 1.2 Control Field
The Control field designates the frames as Supervisory (S),
Nonsequenced (NS), or Information (I).

5.10.1.2.1 Supervisory Commands: The 3274
supports only the Supervisory commands Receive Ready
(R R) and Receive Not Ready (RNR).
The C-field formats are as follows:
RR

INr

P/F

012

For a detailed description of the SDLC frame format,
refer to IBM Synchronous Data Link Control Generallnformation, GA27-3093. Support of the frame sequence, flag
byte, Address byte, and Frame Check Sequence bytes conforms to the referenced document.

RNA

The 3274 will transmit RNR when the control unit cannot
accept further data from the link.

5.10.1.1 Response Modes
The 3274 unit functions in two link operating modes:
. normal response mode (NRM) and normal disconnect
mode (NDM). In NRM, the 3274 can initiate transmission
and raise the request-to-send signal only as a result of
receiving a frame from the communications controller
which contains the P bit set to 1. Single or multiple frames
may be sent by the 3274. The last frame (or a single frame)
transmitted by the 3274 in response to a command received
with the P bit set to 1 must have the F bit set to 1. When
the ~274 has completed a transmission, a new transmission
cannot be initiated until a subsequent frame is received
from the communications controller which contains the
P bit set to 1. A response transmission initiated by the
3274, which requires acknowledgment from the communications controller, is repeated each time the communications controller polls until the acknowledgment is received.
There is no limit to the number of transmissions. Responses
that require acknowledgment from the communications
controller are I-frames, CMDR, and RR when transmitted
with the F bit set to 0, to report clearing of a busy
condition.

When the reported RNR condition is cleared, the control
unit will transmit an I-frame or R R with the F bit on after
a frame with the P bit on is received.
If the 3274 has received an RNR, an I-frame will not be
transmitted until an R R or I-frame with the poll bit on
is received.
The transmission or receipt of an NS frame does not
indicate the RNR condition has cleared.

•

5. 10. 1.2.2 Nonsequenced Commands and
Responses:

The Nonsequenced commands and responses
listed in Figure 5-45 are supported by the 3274.
Command/Response

C-Field

Hex Code

Set Normal Response
Mode (SNRM) Command

100P0011
01234567

Disconnect
(DISC) Command

010P0011
01234567

Nonsequenced Acknowledgment
(NSA) Response

011F0011
01234567

Request Online
(ROll Response

000F1111
01234567

Command Reject
(CMDR) Response

100F0111
01234567

Test Command/Response

1 1 1 P/F 0 0 1 1
012 3 4567

Exchange Station I D
Command/Response

1 0 1 P/F 1 1 1 1
012 3 4567

Figure 5-45. Nonsequenced Commands and Responses
Supported by 3274
The SNRM command sets the 3274 in NRM. Receipt
of SN RM causes the 3274 to deactivate the physical unit
if it is in active state. The Online and Ownership symbols
are turned off.
The DISC command sets the 3274 in NDM.
The NSA response is sent by the 3274 to acknowledge
receipt and acceptance of the SN RM and DISC commands.
The Test command is used to initiate one round-trip
transmission of test data in both NRM and NDM. The 3274
station will return the Test response without data if buffering is not available to hold the complete test data, or with
data if buffering is available.
The Request on Line (ROL) response is sent by the 3274
in normal disconnect mode (NDM) to request online
status. ROL is sent in response to any command except
Test and XID. ROL is sent in response to the SNRM
command when the 3274 cannot enter NRM.
The CMDR response is implemented by the 3274 as
described in IBM Synchronous Data Link Control Generallnformation, GA27-3093. The CMDR,will be sent in
response to any poll until an SNRM or DISC is received
to reset the control unit.
The Exchange Station Identification (XID) command and
response contains additional data beyond the C byte. The
3274 responds to the XID command in NRM or NDM,
except when a CMDR condition exists, in which case the

CMDR response takes precedence over XID. The request/
response unit (RU) of the XID response consists of 48
bits, defined as follows:
Bits

Meaning

0-3
4-7
8-15
16-27
28-47

I D format B "0000'
PU type B"0010'
Self-description X"OO'
X'017' (3274) and X'018' (3276)
ID number

on all attached 3278s. The timer is reset to zero every time
the 3274 detects a valid outbound frame. The Communication Check symbol is turned off when a valid frame is
received by the station.
If a condition of no line activity is detected by the 3274
for 20 to 25 seconds, the Communication Check symbol is
set on all attached 3278s. The indicator will be turned off
when a valid frame is received.

5.10.3 Hexadecimal Notation and Frame Summary

The 3274 will send X'OOOOO'.

5.10.1.2.3 Information (I) Frame: The Information

Figure 5-46 shows the hexadecimal notation for SDLC
commands and responses.

frame is used to transmit message data. When transmitted,
the I-frame contains a maximum of 256 bytes of RU message data preceded by six bytes of transmission header
(RH).

5.11 SNA INFORMATION
5.11.1 Session Control
Session Control (SC) requests are sent from the host to
establish and maintain a session with 3274. Session Control also provides facilities to clear data flowing within a
session after a catastrophic error occurs and then to
resynchronize the data flow after such an error. All
Session Control commands supported by 3274 are transmitted on the expedited flow. The specific SC function is
identified by the first byte of the Request Unit (RU). The
SC functions supported by 3274 are listed in Figure 5-47.
Function

SNRM
DISC
SIM
NSI
NSP
XID
TEST

5.10.2 Sequence Error Recovery Procedures
A sequence error occurs when the 3274 receives an I-frame
with an incorrect Ns sequence count and valid FCS bytes.
The 3274 does not accept the I-frame that caused the
sequence error and rejects all following I-frames, until
an I-frame is received which contains the correct Ns value,
at which time the sequence error condition is reset.

'93'
'53'
'17'
'13'
'33'

'83'
'43'
'07'
'03'
'23'

'SF'
'F3'

'E3'

Nonsequenced Responses

The 3274 transmits I-frames in the sequence indicated
by the last Nr count received, which may include retransmission of previously transmitted I-frames that have not
been acknowledged.

NSA
ROL
CMDR
RQI
NSI
XID
TEST

All I-frames are transmitted in contiguous sequence according to the Ns value within the constraints of the modulo
count.

'73'
'1 F'
'97'
'17'
'13'

'63'
'OF'
'87'
'07'
'03'

'SF'
'F3'

'E3'

Supervisory Commands/Responses
(See Legend)

5.10.2.1 Abort Function

RR
RNR
REJ

The abort function is used by the communications controller or by the 3274 when a frame being transmitted is
to be discarded. The abort function is performed by transmitting eight contiguous one bits without zero insertion
at the earliest possible time following recognition of an
abort situation. No FCS is transmitted. When, for example,
the 3274 receives seven contiguous one bits, it discards
the aborted frame. The 3274 employs the abort function
when an equipment malfunction occurs that causes an
erroneous transmission.

'_1'
'-5'
'-9'

Support

X'11 '
X'12'
X'OD'
X'OE'
X'31'
X'32'
X'A1'
X'AO'

Outbound
Outbound
Outbound
Outbound
Outbound
Outbound
Outbound
Outbound

CRV (Crypto Verification)

8
A
C
E

Notify

X'CO'
X'B1 '

Outbound
Inbound

. Hexadecimal digit for " .... "
Nr=

0
1

2
3
4
5
6
7

P/F

0
2
4

3
5
7
9

S
D
F

Hexadecimal digit for "*,,
Ns=

Hex

0
1
2
3
4
5
6
7

0
2
4

6
8
A
C
E

Information Commands/Responses
(See Legend)

Note: SDLC Name Changes
To conform with HDLC the following names have been
changed:
NSA to UA (Unnumbered Acknowledge)
CMDR to FRMR (Frame Reject)
ROL to DM (Disconnect Mode)
ROI to RIM (Request Initialization)
NSI to UI (Unnumbered Informational)

5.10.2.2 Timeout Controls
When the 3274 is attached point-to-point or multipoint and
does not recognize any valid outbound frame for 20 to 25
seconds, a nonproductive timeout occurs. This timeout
causes the 3274 to set the Communication Check symbol

RU Byte

Activate Physical Unit (ACTPU)
Deactivate Physical Unit (DACTPU)
Activate Logical Unit (ACTLU)
Deactivate Logical Unit (DACTLU)
Bind
Unbind
Clear
Start Data Traffic (SOT)

Legend

Nonsequenced Commands

Figure 5-47. Session Control Functions Supported by 3274

5.11.2 Data Flow Control
Data Flow Control (DFC) requests are passed between the
application program and 3274 to provide control over
session data flow. Data Flow Control functions are identified by the setting of the RU type bit to B'l' and the Subsystem Control bit to B'O'. The DFC requests listed in
Figure 5-48 are supported by 3274.
Function

Flow

RU Byte

Support

Cancel
Bid
Chase
Signal
SHUTD
SHUTC
LUSTAT
RTR

Normal
Normal
Normal
Expedited
Expedited
Expedited
Normal
Normal

X'83'
X'C8'
X'84'
X'C9'
X'CO'
X'C1'
X'04'
X'05'

Inbound/Outbound
Outbound
Outbound
Inbound/Outbound
Outbound
Inbound
Inbound
Inbound
(LU types 1,3)

Figure 5-48. Data Flow Control Requests Supported
by 3274

Figure 5-46. SDLC Commands and Responses
in Hexadecimal Notation

SY27-2512-3

5-25

SY27-2512-3

5-26

5.11.3 Transmission Header

5.11.4 Request/Response Header

The format of the transmission header is shown in
Figure 5-49.

The format of the request/response header is shown in
Figure 5-50.

THO

TH1

TH2

.
L
lls

TH3

°__

: : 2: ~: ~-3~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:~:-41

TH5

RHO

_L_7::_-_<

225

Recovery

•
•

Device is disabled if not
recoverable
nn/l

ECS Feature Command Queue
Failure

1 or 2

226

Reset key

Sense Codes
SNA Non SNA

Applicable
Features

•

ECS adapter error (see
device MIM)

D81C

DC/US

Category A
Terminal ECS

Category A
Terminal ECS
Feature

Device POR if
disabled

•

Device POR

• Transmission error while
communicating with ECS
Feature

081C

DC/US

•
•

Reset key

•

Models A,C, and
D with Color

• Convergence logic (see
device MIM)

Models A,C, and
D with Color

• See Printer PDG

• Printer error

081C

EC/IR/US

Type A
Printer

• Device POR

• Replace ECSA card
in 3278/3279

Type B
Adapter

• A cycle sharing command/data
operation failed in transmission

Probable Causel
Action

227

• Operation is retried and counter
is incremented

•
228

229

231

If retry fails, the terminal is
disabled

Convergence eackup Storage
Failure

nn/l

Convergence Feature Memory
Failure

nn/l

Printer Equipment Check

nn/l

1010

A2/1

1010

A2/1

•

)( bIi! 228

)( bIi! 229

•
•

Retry operation
Reset key
Retry operation

8attery failure (see device
MIM)

•

IML

• Type 8 adapter logic

•

IML

• Type B device

Printer reported an unrecoverable
error to the control unit

234

Display has ECS Adapter
but no Extended ROS

270

Unrecoverable Machine Check

)( bIi! 234

• The control unit detected an
unrecoverable error from the
Type 8 adapter
• Type 8 adapter is disabled
• Type A terminals are not affected
271

Adapter Disabled-Interrupt
Threshold Exceeded
• Category 8 device exceeded
interrupt threshold value within
1 second
• Type B adapter disabled

•

Use /3 test to determine
failing device as indicated
by '-' on line 2

•

Device log for failing device
should indicate 279

Category B
Terminal

• Type A terminals are not affected
272

Unrecoverable Overrun

1010

A2/1

•

Host Recovery

• Type 8 adapter logic

0828

DC/US

• Type B adapter requested data
and the request was not
serviced within control unit cycle
steal I/O time and recovery
attempts were unsuccessful
• Type 8 adapter disabled
*Where nn

.... _....

= port ID =00 - 31
t

Type 8
Adapter

nnn
Code
273

Displayed on

Sense Codes

Recovery

Probable Causel
Action

SNA

NonSNA

All

One

Indicator
Displayed

•

IML

• Type 8 adapter logic

Category 8
Terminal

•

POR device

• Type 8 device error

081C

DC/US

Category 8
Terminal

nn/1

• See Printer PDG

•

Printer error

081C

EC/IR/US

Category B
Printer

nn/l

• See Printer PDG

•

Printer error

0828

EC/US

Category 8
Printer

nn/1

•

Host recovery

• Type 8 device buffer

0828

DC/US

Category 8
Terminal

•

POR device

081C

DC/US

•

Host recovery

081C

DC/US

Error .Description

Operational
Indicators

Test No.
for Log*

Adapter Timeout

1010

A2/1

nn/1

Counter
Incremented

Log
Only

• Type 8 adapter did not return
I/O operation ending status
within 2 seconds

Applicable
Features

• Type 8 adapter is disabled
• Type A adapter is unaffected
274

Solid 8usy

•

An EAU command sent to the
terminal, and 8usy condition does
not clear

• Terminal is disabled because of
error
275

Equipment Check and Printer Not
Ready
• Printer has returned S~nse of
Equipment Check and Not Ready

276

Equipment Check - Printer

277

•

Printer has returned Sense of
malfunction while printing

•

Print-buffer contents not affected

Device Check

•
•
•
278

Host error recovery should clear
error
Device disabled if recovery is
unsuccessful

Coax Parity

•

•
279

Device buffer parity error

•

Device error

Type 8
Adapter

• Type 8 D/R

Device disabled if retry fails

1010

nn/1

•

POR device

•

IML

Device exceeded interrupt
threshold value

Category 8
Terminal
Category B
Terminal

Device with nnn=279 in log
caused adapter to be disabled
DC/US

• Type 8 device

Type 8 adapter disabled

• Coax

•

Parity error while communicating
with device via coax

Interrupt Threshold Exceeded

•

nn/1

• Search device error log to
determine failing device
,.

•

081C

Use /3 test also

*Where nn = port ID = 00·31

SY27 -2512-3

8-5

8-6

SY27 -2512-3

nnn
Code

Error Description

292

Illegal Entry in Error Queue

•
293

294

Test No.
for Log*

Counter
Incremented

Log
Only

Displayed on
All
One

A1/1

Indicator
Displayed

)(

292

Illegal combination of status in
error queue for Type A adapter

Unconfigured Port Address

•

Operational
Indicators

A 1/1

~ 293

Input received from a device
address not in configu ration
table

Unexpected End Cycle Share

A1/1

)(

I!'Jiil

294

• . Control unit received End of
Cycle Share when none was
initiated
295

Invalid DCA Status

•

296

Al/1

)( I!'Jiil 295

Undefined combination of status
bits received from Type A
adapter

Lost Status

Al/1

)( ~ 296

• Type A adapter keystroke/status
buffers reached threshold (64CTR
overflow)

•
297

Probable Causel
Action

Sense Codes
SNA NonSNA

Applicable
Features

• Type A adapter

Type A
Adapter

•

Type A
Adapter

• Type A adapter

Type A
Adapter

• Type A adapter

Type A
Adapter

• Type A adapter

Type A
Adapter

•
•

Reset key

•
•

Reset key

•

Reset key

•

Retry operation

•
•

Reset key

•
•

Reset key

•
•

Reset key

• Type A adapter

Retry operation

• Type A device

•

POR device

• Type A adapter

Retry operation

Ensure that port address
is included in
customizing

Retry operation

Status was lost during an
attempted restart

Adapter Stopped and Was Restarted

•

Recovery

Al/1

The DCA stayed active for more
than the allowed period of time.

• The DCA was reset and successfully restarted

298

299

Command Queue Cycle Share Machine
Check

•

Machine check during command
queue cycle share operation

•

Operation is retried. If
unsuccessful, coax port disabled

Non-Command Queue Cycle Share
Machine Check

•

Cycle Share machine check when
no command queue operation was
in progress

• CU cannot isolate failing port
*Where nn = port 10 = 00 - 31

A1i1

)( ~ 298

• Type A device

•

Alil

)( ~ 299

•
•

Reset key
Retry operation

Use device logs and 13
test to isolate

• Type A adapter

Type A
Adapter

...

Displayed on
nnn
Code
2%%
(2EE)

310

311

320

Error Description

330

nn/1

•

displays
as NNN
of 2EE
in error
log
display

340

Feature is not supported with
configuration selected during
customizing.

•

Feature did not respond when
terminal was initialized.

•

Keyboard 10 does not match
control unit keyboard table.

CCA Machine Check

•

Control logic to CCA
operation error; if retry OK,
is transparent to adapter control
code

•

If recovery attempts are
unsuccessful, the error is posted
and the adapter is disabled

CCA Invalid Status

•

Invalid basic status bit
combination has been received
from the CCA

•

Adapter disabled

CCA Machine Check (SOLC)

1001

Counter
Incremented

Log
Only

All

One
X

Indicator
Displayed

)(

2 ~.>; ':;.:;

310

Recovery

•
•

•

Reset key

Probable Causel
Action

NonSNA

Applicable
Features

Features

SNA

•

Machine features do not
match configuration

•

Feature logic error

•

CCA

CCA - SSC

Retry operation

IML

Sense Codes

1001

)(

311

•

IML

•

CCA

CCA - SSC

)(

320

•

IML

•

CCA

CCA-SOLC

)(

321

•

IML

•

CCA

CCA-SOLC

)(

330

•

IML

•

HPCA

HPCA-SOLC

)(

331

•

IML

•

HPCA

HPCA-SOLC

)(

340

•

IML

•

LCA adapter

Model A

Recovery attempts have failed
Adapter is disabled

CCA Invalid Status (SOLC)

•

Invalid status has been received
from the CCA

•

Adapter is disabled

HPCA Machine Check

•
•
331

Test No.
for Log*

Unsupported Feature Attached

•
•
321

Operational
Indicators

1001

Recovery attempts have failed
Adapter is disabled

HPCA Invalid Status

•

Inval id status has been .received
from the HPCA

•

Adapter is disabled

LCA Unrecoverable Machine Check

•

An LCA adapter machine has
occurred

•

Retry has failed

•
•

Adapter is disabled

1001

LCA issues 'disconnect in'

*Where nn = port 10 = 00 - 31

SY27-2S12-3

8-7

SY27-2512-3

nnn
Code

Error Description

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

Displayed on
All
One

341

LCA Invalid Function Request

1001

AO/1

Indicator
Displayed

)(

341

Probable Causel
Action

Sense Codes
SNA Non SNA

•

• Control logic

Model A

IML

• The LCA adapter has received
an invalid request from control
logic
342

LCA Open Error

•
350

Applicable
Features

Recovery

•

LCA adapter

•

Microcode

•

IML

•

LCA adapter error

Model A

350

•

IML

•

LHA adapter

Model B

351

•

IML

•

LHA adapter

Model B

352

•

IML

•

LHA adapter

Model B

)( ~ 353

•

IML

•

LHA adapter

Model B

1001

AO/1

)( ~ 342

1001

AO/1

)(

1001

AO/l

)(

1001

AO/l

)(

1001

AO/1

LCA issues 'disconnect in'

LHA Unrecoverable Machine Check
• Adapter is disabled

•
351

LHA issues Disconnect In

LHA (B) Invalid Status or Sense
• The LHA adapter has presented
Invalid Status to the control
logic
• The adapter is disabled

352

LHA Invalid Request Code

•

LHA (B) adapter sent invalid
request code

• Adapter is disabled
353

LHA Invalid Device Address

•

LHA (B) adapter sent invalid
address

• Adapter is disabled
354

LHA Unrecoverable Machine Check
During Initialization

•
•

1001

AD/1

)(

~354

•

IML

LHA (B) adapter returned
machine check during
initialization

•

Check that address range
jumpers match number of
devices selected at customizing time

•

LHA adapter

•

LHA adapter

Recovery has failed

• Adapter is disabled
355

Adapter I/O Parity Error
• The 3274 Model B (adapter)
detected a parity error when
accessing its device table buffer
• Adapter not disabled

*Where nn == port ID

= 00 - 31

AO/1

)(

355

•

Reset key

•

Retry operation

Displayed on
nnn
Code

Error Description

356

Model B Adapter Cycle Share

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

All

One

Probable Causel
Action

Indicator
Displayed Recovery

Sense Codes
SNA

Non SNA

Applicable
Features

)( ~ 356

•

IML

•

LHA adapter

Model B

)(

357

•

IML

•

LHA adapter

Model B

)(

~ 360

•

IML

• SLHA adapter

)( ~ 361

•

IML

• SLHA adapter

Model D

l!!Ii! 362

•
•

Host recovery

• SLHA adapter

Model 0

AO/l

1001

AO/l

1001

AO/l

1001

AO/1

1001

AO/1

Mach i ne Check
• CU detected a cycle share
machine check after retries
exhausted
• Adapter disabled
357

Adapter Lockout (LHA)
• Adapter is locked out to con·
troller attempts to present status
• Adapter disabled

360

SLHA Unrecoverable Machine Check

•
•
361

362

Recovery has failed
Adapter is disabled

SLHA Adapter has Presented Infor·
mation or a Machine Check has
Occurred

•

Adapter is disabled

Model 0 Cycle Share Machine

Check
Model 10 sense sent to host
Note: Counter incremented on a/l
errors, NNN and operational
indicators set if unrecoverable

•

363

Model D

Model 0 Unrecoverable Machine
Check

1001

AO/1

Reset key to
unlock
keyboard

)(

363

•

IML

• SLHA adapter

Model 0

)(

~ 364

•
•
•

Reset key

• SLHA adapter

Model D

Host recovery

•

IML

•
•
•

All Models

• Adapter is disabled
364

381

SLHA Adapter Parity Error

•

Parity error detected during an
I/O transfer

•

Data check (sense) sent to host

Unrecoverable Control Logic Error

•
390

•

A3/1

)( ~ 381

Retry operation

Host communications disabled

0001 or
0011
throug
1
Unrecoverable storage parity error
0111
Host communications disabled

Storage Parity Error

•

0010

*Where nn = port 10

)(

~ 390

•

IML

Control logic
Storage
Microcode

•

Control logic

•

Storage

•

See MIM Figure 2·8 for
storage card

= 00·31
SV27 -2512-3

8-9

SY27-2512-3

nnn
Code

Error Description

391

Control Logic Machine Check

397

398

399

•

Unrecoverable control logic error

•

Host communications disabled

Encrypt/Decrypt Adapter
Permanent Error

•

All attempts for recovery have
been exhausted

•

Adapter disabled

•

Non-Encrypt/Decrypt operations
may be run

Encrypt/Decrypt Parity Error

•

Master key parity error

•
•
•

Retry attempts failed

Test No.
for Log*

Counter
Incremented

0010
or
1101

1110

Log
Only

Displayed on
One
All

Indicator
Displayed

)(

~ 391

Recovery

Probable Causel
Action

Sense Codes
SNA Non SNA

Applicable
Features

•

• Control logic

All Models

IML

• Storage

•

Microcode

A3/1

)(

~ 397

•

IML

•

Encrypt/Decrypt logic

0848

Encrypt/
Decrypt

A2/1

)(

•
•

IML

• Weak or defective battery

0848

Enter master key

•

Refer to master key entry
and verification procedure

Encrypt/
Decrypt

•

IML

•

Encrypt/Decrypt logic

398

Adapter is disabled
Non-Encrypt/Decrypt operations
may be run

Encrypt/Decrypt Adapter Failure

•

Retry attempts failed

•

Adapter is disabled

•

Non-Encrypt/Decrypt operations
may still be run

*Where nn

Operational
Indicators

8·10

= port

= 00 - 31

A2/1

)(

~ 399

0848

Encrypt/
Decrypt

...

nnn
Code
401

402
,

Error Description

Operational
Indicators

Test No.
for Log*

Command Reject

AO/l

•

Invalid command received from
host

•

See Note 1

Invalid Out-of-Range Buffer Address

403

•

SNA generates X'1005',
parameter error

•

See Note 2

Data after Read/Read Modified/Equ
Invalid or Out of Range

•
•
404

405

nn/l

Log
Only

Displayed on
One
All

Indicator
Displayed

)( PROG401

)( PROG 402

)( PROG403

Recovery

•
•
•

Host recovery

•

Host recovery

•
•

Reset key

•
•
•

Host recovery

•
•
•

Host recovery

•

Host recovery

•
•

Reset key

Sense Codes

Probable Causel
Action

SNA

NonSNA

•

Host has sent inval id
command

1003

Com
Rej

All Models

•

Host has sent invalid order
parameters

1005

Op
Ck

Models A,
C-BSC/SDLC,
and D

•

Host has sent invalid data
after RD, Rd Mod, EAU
command

1003

Op
Ck

Models A,
C-BSC/SD LC,
and D

•

Host has sent an order
(SBA, RA, EAU, or SF)
without required data bytes

1005

Op
Ck

Host has sent a copy
command with invalid
parameters

Reset key

Applicable
Features

Retry operation

Reset key
Retry operation

SNA generates X'1003', Function
Not Supported (see Note 1)

nn/l

)( PROG 4041

BSC generates a Sense Operation
Check; SNA generates X'1005',
Parameter Error (see Note 2)

Invalid Copy Command

•

Counter
Incremented

Invalid or out-of-range data

SBA/RA/EAU or SF Order without
Valid Parameters

•

BSC generates an operation check

nn/1

)( PROGA05

Reset key
Retry operation

•

Models A,

C-BSC/SD LC,
and D

Op
Ck

CCA-BSC

Retry operation

Notes:
1. SNA generates code X'1003', function
not supported:

•

•
•

Unsupported session control request
Unsupported data control request
Signal code not X'OOO10000'

•
•
•

Network control request

•

MF to non-field location

F M data stream
Invalid command: data after Read,
RM,RMA,EAU

2. Parameter error - invalid address after
SBA, RA, or EAU order (SBA, RA, EAU
without parameters) or SCS parameter
error
Invalid parameters following SA,
SFE, and MF

*Where nn

= port

I D = 00-31

SY27-2S12-3

B·11

SY27-2S12-3

nnn
Code

Error Description

406

Invalid Command Sequence

•
407

Operational
Indicators

Counter
Incremented

Log
Only

Displayed on
One
All

nn/1

Indicator
Displayed
)( PROG406

Invalid command sequence was
detected

LHA Sent Operation Check

•

Test No.
for Log*

nn/l

PROG'407

Invalid data stream from host

Recovery

8-12

ProbableCausel
Action

Sense CodeS.
SNA Non SNA

Applicable
Features

Op
Ck

Models e-8SC
and D

Op
Ck

Model 8

Op
Ck

Model C-8Se

•
•

Reset key
Retry operation

• A cew was chained to a
write cew that had the
start print bit set in the
wce

•
•

Reset key

•

Host send:
a) S8A RA, or EAU with an
inval id address

Retry operation

b) a valid order without
required data
c) a write type command
with start print bit
chained to the next
command
d) a wec with bit 1 off.
408

(BSC) Count Exceeded

•
•
410

412

nn/1

PROG 408

PROG410

RU greater than 1536

•
•

Reset key
Retry operation

•

Reset key

•

Retry operation

•
•

Reset key

•
•

Reset key

•
•

Reset key

• 3274 unable to handle host
data stream

•

Data stream has excessive
program tab orders

•

Host software

1002

Model A

•

Host software

1002

Models A and
C-SDLC

•

Host software

1002

•
•

Host software

1003

Program check
Host-sent RU larger than control
unit can support

nn/1

PROG 411

LU1 RU'is greater than
BIN 0 specification

Short Record

•

Sense/status set to OPCHECK and
EOT sent to host

RU Length Error

•

Adapter read buffer unavailable

RU Length Error

•
•
•
411

AO/1

nn/1

PROG 412

Program check

Retry operation

Models A and
C-SDLC

Retry operation

• A 'short' record was detected
• Control unit sends SNA a
negative response of X' 1002',
RU lengt~ error
413

Function Not Supported

nn/1

• Crypto verification (CRV)
received but no crypto
session has been established

PROG413

Retry operation

Model CSOLe
Encrypt/
Decrypt

Procedural error

• See 401, Note 1
*Where nn

= port

= 00 - 31

....

...

•

nnn
Code

Error Description

414

Encrypt/Decrypt Data Error

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

nn/1

Displayed on
All
One
X

Indicator
Displayed
>C PROG414

• SNA program check

•

420

Invalid pad count or non-modulo8 RU has been received during
an Encrypt/Decrypt session

Exception Response Not Allowed

nn/1

)( PROG420

• SNA program check

421

Definite Response Not Allowed

nn/l

)( PROG421

• SNA program check

422

No Response Not All owed

•

nn/l

)( PROG422

Program check

Recovery

Sense Codes

Probable Cause/
Action

SNA

Non SNA

Applicable
Features

1001

Model CSDLC
Encrypt/
Decrypt

4006

Models A and
C-SDLC

4007

Models A and
C-SDLC

•
•
•

Reset key

•

Host software

Retry operation

•

Procedural error

•

Non-Encrypt/
Decrypt operations
may be run

•

Reset key

•

Retry operation

Host has sent invalid
or incorrect data

•

Inform host
programmer

•

L1C carried exception
response when Bind
specified definite response

•
•

Reset key

•

Host has sent invalid
or incorrect data

•

Inform host
programmer

•

L1C carried definite
response when Bind
specified exception
response

•

Reset key

•

Host software

400A -

•

Retry operation

Models A and
C-SDLC

•

Host software

400F

Models A and
C-SDLC

•

Host software

2001

Models A and
C-SDLC

Host software

2002

Models A and
C-SDLC

2003

Models A and
C-SDLC

Inform host
programmer

Retry operation

• • Inform host
programmer
423

FI (Format Indicator) Bit Not
Allowed

•
430

nn/1

>C PROG423

Program check

Sequence Number Error

nn/1

)( PROG430

• SNAprogram check

431

Chaining Error

•
432

nn/l

)( PROG'431,

SNA program check

Bracket Error
• SNA program check

*Where nn

•

Reset key

•
•

Retry operation

•
•

Reset key

•

Inform host
programmer

•
•

Reset key
Retry operation
Inform host
programmer

•
•

•
•
•

Resetkey

•
•

•
-

nn/l

'< .PROG432 '

Inform host
programmer

Retry operation

Error in the chain
indicator sequence
Host software
Brackets incorrectly used

Inform host
programmer

= port ID = 00 - 31
SY27-2512-3

8-13

SY27-2512-3

nnn
Code

Error Description

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

433

Data Traffic Reset

nn/l

•

)( P'POG 433

nn/l

)( PROG434

SNA program check

Encrypt/Decrypt Protocol
Violation

439

Indicator
Displayed

SNA program check

Half-Duplex Error (Direction
Error)

434

Displayed on
All
One

nn/l

)( PROG439

• SNA program check

440

Session Limit Exceeded

•

none

SNA-program check

Bracket Bid Reject Not Ready to
Receive (RTR) Returned or Receiver
in Transmit

441

nn/l

none

Request Not Executable

Probable Causel
Action

Sense Codes
SNA Non SNA

•

Reset key

•

Host software

2005

•
•

Retry operation

Models A and
C-SDLC

•
•

Host software

2004

Models A and
C-SDLC

2009

Model CSDLC
Encrypt/
Decrypt

Inform host
programmer

•
•
•

Reset key

•

Reset key

•
•

Retry operation

•

Non-Encrypt/Decrypt
operations may be run

•
•
•

Reset key

•

Non-Encrypt/Decrypt
operations may be run

•
•

Reset key

Retry operation
Inform host
programmer

•
•

Inform host
programmer

Session Already Bound

Host software

0805

Models A and
C-SDLC

•

Host software

0813
or
081B

Models A and
C-SDLC

Inform host
programmer

Retry operation

nn/l

)( PROG442

•

Device POR

•

Terminal error - refer
to 2nn portion of /1
test

081C

Models A and
C-SDLC

)( PROG 443

•

Device POR

•
•

Host software

0829

Models A and
C-SDLC

nnll

•
•

Host software

0815

Models A and
C-SDLC

0821

Models A and
C-SDLC

none

•

Device POR

• SNA program check
445

An invalid CRV has been
received

Retry operation

• SNA program check

444

Host software

Function request cannot be
executed because of a
permanent hardware error

Change Direction Required

443

Normal Flow request was
received by SNA while in
half-duplex Send state

•

• SNA program check

•

Applicable
Features

Recovery

• Inform host
programmer

• SNA program check

442

8-14

ACTLU Not Sent (cold
start or Error Recovery
.Procedure)

nn/l

)( PROG445

•

Device POR

•

Request required a Normal
Flow reply, but SNA in
Receive state

The requested function is
already active
Host software

nnn
Code
450

Error Description

Operational
Indicators

Test No.
for Log*

Bind Reject-Profile Error

nn/l

•

451

452

453

454

455

456

457

PROG450

nn/l

PROG451

SNA program check

Sense Codes

Recovery

Probable Causel
Action

SNA

NonSNA

•

Reset key

•

Host software

0821

•
•

Retry operation

Models A and
C-SDLC

•

Host software

0821

Models Aand
C-SDLC

•

Host software

0821

Models A and
C-SDLC

•

Host software

0821

Models A and
C-SDLC

•

Host software

0821

Models A and
C-SDLC

•

Host software

0821

Models A and
C-SDLC

•

Host software

0821

Models A and
C-SDLC

•
•

Host software

0821

Model CSDLC
Encrypt/
Decrypt

•

nn/l

)( PROG'452

nn/l

PROG453

nn/l

PROG454,

nn/l

)( PROG455

nn/l

PROG456

nn/l

)C PROG457:

Applicable
Features

Inform host
programmer
Reset key

• Retry operation

SNA program check: invalid
session parameter

Bind Reject-Encrypt/Decrypt
Parameter Error

•

SNA program check: invalid
session parameter

Bind Reject-LU 1 Error

•

SNA program check: invalid
session parameter

Bind Reject-LU Profile Error

•

One

SNA program check: invalid
session parameter

Bind Reject-Screen Size Spec. Error

•

All

Indicator
Displayed

SNA program check: invalid
session parameter

Bind Reject-Common Protocol Error

•

Displayed on

SNA program check: invalid
session parameter

Bind Reject-Secondary Protocol Error

•

Log
Only

SNA program check: invalid
session parameter

Bind Reject-Primary Protocol Error

•

Counter
Incremented

...

•

Inform host
programmer

•

Reset key

•
•

Retry operation

•

Reset key

•

Retry operation

•

Inform host
programmer

•
•
•

Reset key

•
•
•

Reset key

•
•

Reset key

•

Inform host
programmer

•

Reset key

•
•

Retry operation

•

Non- Encrypt/Decrypt
Qtperations may be run

Inform host
programmer

Retry operation
Inform host
programmer

Retry operation

Inform host
programmer

Bind specification for
Encrypt/Decrypt had an
error in byte 26 or 27,
Encrypt/Decrypt was
specified, and the Encrypt/
Decrypt feature is not
present, or a CRV was
received in CRV invalid
state.

*Where nn = port ID = 00 - 31

SY27-2512-3

8-15

SY27 -2512-3

nnn
Code
458

Error Description

Operational
Indicators

Bind Reject-Encrypt/Decrypt
Test

Test No.
for Log*

Counter
Incren'1ented

Log
Only

nn/l

Displayed on
All
One

Indicator
Displayed
~ PROG458.

Recovery

•
•
•

460

Printer Authorization Matrix
Error

468

Printef Detected Error in
LU 1 Data Stream

nn/l

470

Unsupported Order

471

472

473

)C PROG460

SFAP (Structured Field and
Attribute Processing) Data
Stream Error

Read Partition Structured Field
State Error

PS Addressing Error

)( PROG470

)( PROG471

)( PROG472

)( PROG473

Probable Causel
Action

Host recovery
• The test value (N) from the
or
host does not match the
Control Unit key must
one sent by the 3274
be changed (the cus• There is a master key mistomer's security
match between the host
administrator should
and the 3274
be notified)
• See Planning and Setup
Non-Encrypt/Decrypt
Guide
operations may be run

•
•

Reset key
Retry operation

•

Invalid print matrix sent
from host or Load Key hit
at time when matrix not on
screen

•

See Printer PDG

•

Host software

•
•
•

Reset key

Host software error
• Unsupported
order

•
•

•
-

8-16

•
•
•

•

Retry operation

•

Application program
error
Reset key
Retry operation
Appl ication program
error
Reset key
Retry operation
Appl ication program
error
Reset key

•

474

No Extended QCB Configured
for this Device

)( PROG474

0821

Applicable
Features
Model CSDLC
Encrypt/
Decrypt

All Models

Models A and
C-SDLC

100C Op
Ck

Models A,
C, and 0

decoded inS F AP data
stream

•

Host software error

•

Refer to App. C

1003
or
1005

Op
Ck

Models A,
C, and D

•
•

Host software error

0871

Op
Ck

Models A,
C, and 0

•

Host software error

084C Op
Ck

Models A,
C, and D

Models A,
C, and 0

• Application program •
Retry operation

Sense Codes
SNA Non SNA

Refer to App. C

error

AP data stream
• SF
should not be sent

AP data stream send -• SF
no ext. DBC available

1003

Op
Ck

•

Host software

1001

Op
Ck

to this device
475

498

WCC has Start Print Bit Set
but Not Last Structured Field

Negative Response Received

•

•
499

lin/1

)( PROG

No SNA sense returned

*Where nn = port I D '" 00 - 31

Reset key
Retry operation
Application program
error
Reset key

Model 0
SNA BSC

nn/l

)( PROG498

• Retry operation
•
Inform host
• programmer

•

Host software

Models A and
C-SDLC

nn/l

)C PROG499

• Reset key

•

Host software

Models A and
C-SDLC

No SNA sense returned

SNA program check.

•
•
•

SNA program check

Exception Request

•
•

• Inform host

Retry operation

•

programmer

Displayed on
nnn
Code
501

Error Description

Operational
Indicators

Test No.
for Log*

Counter
Incremented

•

AO/1

- (SDLC)
9 (BSC)

•

502

503

505

510

3274 Model C - Data
Set Ready Line Dropped

3274 Models A, B, and D
Channel Not Online

Clear to Send Not Present

•

Clear to send not present while
request to send was on

•

Adapter indicates DCE error or
write timeout

•

DSRisup

AO/1

Log
Only

One

)( ~501

All

)( ~501

Sense Codes
Indicator
Displayed

)( ~502

Recovery

•

Indieator is reset when
DSR is restored

•
•

Reset keyboard

•

Check modem cable wrap
switch

•

Power/Interface switch in
OFFLINE position

•

Channel adapter

•

Channel/cables

•
•

Check data set

• Set power/inter-switch
to ONLINE position

•

Reset key

•

Retry operation

)( ~503

•
•

•

Selective reset sequence was
received for this address

•

Keyboard is inhibited, Reset
key required to clear

•

3274 Model C Disconnected
from Network

)( ~505

•

3274 Model A Connection
Required

)( ~505

•

3274 Models Band DSystem Reset

)( ~505

• The physical unit (SNA state)
is not active
*Where nn

= port

Retry operation

Missing DSR

SNA

Non SNA

Applicable
Features

Model C·
SDLC/BSC

Models A,
B, and 0

Model C

Models B
and 0

Check data set

Run wrap test

• Check - 8.5 volts F4

Selective Reset

Physical Unit Not Active

Probable Causel
Action

)( ~510

Reset key
Retry operation

• The channel issued
selective reset to clear
an error condition
it

Use host error logs to
determine error

SNRM required from
network

•

Normal state after 1M L
or disconnect has been
received

Model C

•

Connect is required
from the host

•

Could result from a
connection problem
(see nnn 525).

Model A

•

The first command
from the host other
than a TIO, Sense, or
NOP will reset

•

Normal state after IML.

Model B
or D

•

AID generating keys
will present attention
status to channel
if polling. Reset and
retry.

• A system reset was
received from the
channel

•

Host issue ACTPU

•

Retry operation

• ACTPU is required from
host

Models A
and C-SDLC

• Cheek·8. 5 vol ts Fuse 4

= 00·31
SY27 -2512-3

8-17

SY27-2S12-3

nnn
Code
511

512

Error Description
Disconnect Received While PU
Active

•
•

Physical unit is deactivated

•

Control unit set to Not Initialized

514

518

519

Test No.
for Log*

Counter
Incremented

Log
Only

Displayed on
One
All

AD/1

AD!l

Indicator
Displayed

Recovery

Probable Causel
Action

Sense Codes
SNA Non SNA

Applicable
Features..

)( ~511

•

Connect required
from host

•

Host issued disconnect
while PU was active

Model C

)( ~512

•

ACTPU is required
from host

•

Host sent connect
when PU was already
connected

Model A

)( ~514

•

New connect with
valid data required
from host

•

Host sent connect with:

Exception condition

Connect Received and Already
Connected

•
•
•

Operational
Indicators

B-18

Exception condition
Physical unit is deactivated
Control unit set to not
initialized

Connect Error - Rejected

Segmenting Error

•

The terminal is closed and
reopened

•

All physical and logical units
are deactivated

Count ExceededlWrong Length

AD!l

- Odd-number buffer
length specified
- Or the buffer size was
not Iarge enough for t~e
link header, the TH,
RH, and 64-byte RU.

)( ~518

•

A SNRM is required
from the host

•

An SNA segment was
received with improper
sequencing in the TH
MPF bits

Model CSDLC

)( ~519

•

Host recovery

•

CCA: Host sent message
received larger than control unit buffer.

Com
Rej

Model CSOLC

•

HPCA: Host sent a message larger than CU buffer.
Receive count will not be
updated, causing retransmission by host

•

Improper buffer size
specified in NCP.

SOLC

Message

52D

Nonproductive readout

-"---

·Where nn

AD/l

-..-...............

port 10 = DD - 31

__-....

Model A

)(~;: 52'0

•

Wi II reset by
receipt of a
val id frame or
frame containing a poll.

No host activity
• Verify
• status ofoperational
communications network

...
Displayed on

nnn
Code

Error Description

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

All

One

Indicator
Displayed

521

Idle Timeout

AO/l

•
525

528

No activity on line for last
20 seconds (no flags
receivedl

Connection Problem

•

Condition exists on lines that
prevent establishing or
reestablishing communication
with host

•

Status is posted after 20 Write
entries, 20 ROLs, 20 CRs,
20 X I Ds, or 20 NSAs

Command Reject

•

~521

Recovery

Sense Codes

Probable Causel
Action

SNA NonSNA

• No host activity

Model C·
SDLC

• Will reset by receipt
of a valid frame or
frame containing a
poll

•

Verify operational status
of communications network

Applicable
Features

AO/l

)(~525

•

Host recovery

•

Communications problem
between host and control
unit

Model C·
SDLC

AO/l

)( ~528

•
•

Host recovery

•

Adapter received invalid Nr
sequence count in an infor·
mation or supervisory frame
with good FCS, or

Model C·
SDLC

•

Received command with data
that has no data field defined,

Model C·
SDLC

Model C

All PUs and LUs are deactivated

•

SN RM required
Inform host
programmer

529

530

DCE Error

•

Unexpected communication error
has occurred

•

Host adapter is disabled and
Reenable is attempted

Write Timeout

•

•
•
531

)( ~529

•

DCE error other than the loss
of DSR (NNN501) or loss of
CTS (NNN502).

•

Ru n wrap test
Check modem

Host recovery

•
•

SNRM required

•

CTS may have dropped
during transmission or
clocking signal is not
available from modem

•
•

Run wrap test

Host recovery

AO/1

11-HPCA
CCA·SOLC

)(·~530

•
•

8-CCA·BSC

In SOLC, host adapter is disabled
and an attempt is made to
reenable.

OSR is ok

Check modem

All PUs and LUs are deactivated

NAK Sent

Received an undefined or non·
implemented command field
in a frame with good FCS

• SNRM required

Microcode has issued a command
to the CCA and after 1 second
no acknowledgment has been
received

• The contents of the screen are
restored to initial state on
detection of the error.

*Where nn

AO/1

•

port 10 = 00 - 31

AD/1

~531

•

Host recovery

•

Retransmit data

• The Communications
Reminder will be
turned off upon
successful retry from
the host.

SY27-2512-3

•

Adapter detected BCC
error on a received message
block, or

•

During a read operation, 3
seconds have elapsed with·
out receiving SYN, ETX, or
ETB, or

•

A forward abort (ENO in
text) or TTO (STX ENO) is
received

•

Verify proper operation of
the communications network.

Model C·
BSC

8-19

SY27-2512-3

nnn
Code

Error Description

532

SSC Line Idle

•

533

ENO character received while
adapter was waiting for STX or
SOH (entire message lost)

•

Retransmit last response

•

Host will retransmit last
message

535

Log
Only

Displayed on
All
One

AD/1

•

Host did not return an ACK for
last transmitted text block

•

Adapter sent 15 ENOs to attempt
to solicit an ACK with no response

AD/1

Control Unit Sent 15 ENOs

•

Counter
Incremented

Indicator
Displayed
)(~532

~533

CCA was overrun during a read
operation and data was lost when
ENO received. The control
unit will retransmit its last
response. The host should
retransmit the message that was
lost, or

•

•
•

Test No.
for Log*

Adapter detected seven successive
3-second intervals without SYN
characters on the line while in
ADPREP mode (monitor line for
poll or selection sequence)

ENO Received

•

534

Operational
Indicators

)(~534

Recovery

•
•

Host recovery
Reset by valid poll or
selection sequence

Host recovery
Retransmit last
message

8-20

Probable Causel
Action

Sense Codes
SNA NonSNA

Applicable
Features

•

No host data being
received

Model CSSC

•
•

Run wrap test

Model C·
SSC

Model CSSC

Verify communications
network operation

•
•
•

Communication error
CCA
Run wrap test

•

Host recovery

•

Host failed to respond

•

A valid poll or
selection will reset
symbol

•

Communications failure

•

Run wrap test

•

Communications failure
between host and control
unit.

•

Verify communications
network operation

•

Run wrap test

•

Retry operation

•
•

Host recovery

EaT sent to host, or
The control unit has acknowledged
a selection sequence and has not
seen a syn (pad syn) for 45
seconds.
Adapter continues to monitor for
a synchronization

15 NAKs Received

•

Text block failed to reach host
after 15 attempts

•
•

EaT is sent to host

AD/1

)( ~535

•

Control unit enters ADPREP mode
(line monitor for poll or selection)

Valid poll or selection
will reset symbol
Retry operation

*Where nn = port ID = 00 - 31

.
nnn
Code

Error Description

Operational
Indicators

Test No.
for Log*

Counter
Incremented

Log
Only

Displayed on
All
One

536

15 Wrong Acknowledge

AO/1

AOl1

540

•

Adapter received wrong ACK in
response to text block transmission (ACKO for ACK 1, or vice
versa), sent ENQ for repeat of
ACK, and received wrong ACK
15 times

•

EOT is sent to host

•

Control unit enters ADPREP
mode (line monitor for poll or
selection)

Command Reject-Not Initialized

•

541

543

AO/l

)(~536

•

Host recovery

Any invalid command detected

Bus Out Check-Parity Check 2

•

Recovery

An invalid command sequence has
been received

Command Reject

•

Indicator
Displayed

AO/1

Bus out parity error was detected
during a channel-selection
operation

Probable Causel
Action

Sense Codes
SNA

NonSNA

• Host-to-control-unit communications error (dropped
• A valid poll or selection
a complete record during
will reset symbol
transmission)
• Retry operation
• Host returns wrong ACK

•
•

A connect is required

•

Retry operation

•
•

Host recovery

•
•

Host recovery

Model CBSC

•

Host sent a restart reset,
read start, write start, read,
write, or write break without a control command
with a val id connect

8200

Model A

•

Host has sent an Invalid
command

8000

Model A

•
•

Channel adapter logic

2002

Model A

•

Channel

2006

Model A

1004

Model A

Retry operation

Applicable
Features

Internal channel cabl es
(Z3-Z6 to tailgate)

• Channel cables/terminators

544

Bus Out Check-Parity Check 1 and 2

•

545

A bus out parity error was detected
while the channel was transferring
data to the control unit.

Equipment Check-Parity Check 1

•

AO/l

A control unit parity error
occurred during a host write
operation or

0001 or
0011-0111
(if not recoverable)

AO/1

•

Use host error logs

•

Host recovery

•

Channel adapter logic

•

Retry operation

•

Internal channel cables
(Z3-Z6 to tailgate)

•
•

Channel

•

Use host error logs

•

LCA adapter logic

•
•

Host recovery

Channel cables/terminators

Retry operation

• A cycle-share 110 error has
occurred during a host
write

*Where nn

= port ID = 00 - 31

SY27-2512-3

8-21

SY27 -2512-3

nnn
Code
546

Error Description
Equipment Check-Parity Check 1
and Modify

•

547

Counter
Incremented

Log
Only

Display on
All
One

0001 or
AO/l
0011-0111 (i f
not recoverable)

AO!l

AO/l

Equipment Check-Parity Check 2

•
548

A control un it parity error or
a cycle steal I/O error has been
detected du ring a host read
operation

Operational
Indicators

Indicator
Displayed

Probable Causel
Action

Sense Codes
SNA Non SNA

Applicable
Features

Host recovery

•

LCA adapter

100C

Model A

IML if recovery fails
(operational
indicators lit)

•

Storage parity error
Use opcode indicators to
isolate solid failures

•

Host recovery

.LCA .adapter logic

1002

Model A

•

Host recovery

•

LCA adapter logic

1001

Model A

•
•
•

Host recovery

•

Byte count specified in host 0800
Read command insufficient
to handle all data in control
unit buffer

Model A

•

Host sent fewer than four
bytes as link header, or

0880

Model A

•

First and second bytes of the
I ink header did not equal the
total byte count received

•

Channel adapter logic

•

I nternal channel cables (2326 to tailgate)

•
•

Channel
Channel cable/terminators

•

Use host error logs

Recovery

•
•

Adapter put bad parity data
on channel during a read

Equipment Check-Control Unit
Machine Check

•

Test No.
for Log*

8-22

Error occurred during an
adapter cycle-share operation

549

550

Data Check

Data Check-Length Check

•

551

AO/l

Set in response to Control,
Write, Write Break commands

Bus Out Check

•

Adapter detected bad parity on
any command or data byte
received from the channel on
Bus Out

*Where nn = port I D = 00 - 31

AO/l

)(~551

•
•
•
•

Retry operation
Inform host
programmer
Host recovery
Retry operation
Inform host
programmer

Host recovery

Models B
and D

Appendix C. Structured Field and Attribute Processing
(SFAP) Data Stream Error Extensions
Bytes 170-174 of the extended device control block (DCB)
are used as a log area for additional information. This complements the PROG 4nn numbers displayed when the error
is detected. Bytes X'170, 171' contain the displacement in
hexadecimal to the byte in the Write Structured Field that
was found to be in error. (The WSF command equals byte
1.) Bytes X'172, 173' contain the displacement into the
particular structured field where the error was detected.
Byte X'174' contains the SF type of the SF that contained
the error.
Figure C-l correlated the SFAP 4nn numbers, the values
found in XDCB X'172-174', the SNA sense code, and a
description of the error. OP check is the sense set for BSC
in all cases.
Bytes 170-174 may be displayed in the following manner.
Enter Test mode by pressing the AL T and TEST keys.
Select the DCB in question by typing in AA/6 (four characters); AA is the coax port number in question (00-31).
(If the device being used for the test is the port in question,
/6 (two characters) will suffice). Press the ENTER key.
The display should now contain:
Line 1
line 2
line 3
line 4
line 5
line 6

AA/6 (same as input)
00

XXXX
XXXX
XXXX
XXXX

xxx X XXXX XXXX
XXXX XXXX XXXX
XXXX XXXX XXXX
XXXX XXXX XXXX

4nn

DCB-'X'
174
172

470
471

0003

471

Sense

Error Description

1003

An unsupported order was
decoded in the data stream.

1003

Unsupported structured field
type.

1003

Advanced Data Stream (WSF)
sent to a device without an
ECSA feature.

471

0007

1005

Out-of-range access to PSS
(RAM out of range).

471

OOOA
OOOB

06
06

1005
1005

Invalid LW-value for Load PSS.
Invalid LH-value for Load PSS.

471

OOOC

1003

Section 10 not supported
(byte 11 not equal to 0).

471

0001

1005

Invalid-length structu red field.

471

XXXX XX

1005

Invalid-partition 10.

471

0005

1003

Invalid mode in Set Reply
mode.

471

0005

1003

Invalid operation in read partition (not query).

471

0005

1003

Alias out of legal range.

471

0006

1005

lrivalid EBCDIC code point.

471

0000

1003

Byte 12, bits 0-4, 7 = 0

471

0002

OpChk

>3K Uncompressed PS data
(BSC only)

471

XXXX XX

472

1005

Invalid reserved bits.

0871

Read partition structured field
state error. Improper sequence
from host.

where:
00 = The displacement from the start of the control block
(in hexadecimal).
XXXX = The hexadecimal representation of the portion of
the control block currently being displayed.
Press the PA 1 key five times: line 2 should change to 40,
80, CO, 10, arid then to 14. (The last two values drop the
low-order digit and really represent X,' 100' and X'140'.)
X'170'-"174' are the first five bytes on line 6.

473

0007

084C

ECSA present, but PSS RAM
addressed not physically
present.

473

0000

084C

Color plane - invalid.

474

1003

No extended DCB configured·
for this device.

475

1001

WCC has Start Print bit set,
but not last structured field.

Note: As part of overall SFAP problem determination, the usage of
the following functions should be kept in mind. If the device in
question does not have an extended DCB (not enough allocated
during customizing), the DCB display procedure (described above)
will inhibit the keyboard with the minus function indicator on the
fourth depression of the PA lor ENTER key. If the device does
not have an ECSA feature, Test 8 (Enter test mode, type in /8,
hit enter) will inhibit the keyboard with a wrong number indicator.
This is also true if SFAP microcode is not configured. If microcode is not configured, the above nnn numbers will not appear.

Figure C-1. SFAP Error Relationships

SY27-2S12-3

C-l

Appendix D. Abbreviations
A

CRV. Crypto verification.

ECS. Extended character set.

ACK. Positive acknowledgement.

CSE. Control storage expansion.

ECSA. Extended character set adapter.

HEX .. Hexadecimal.

ACTLU. Activate logical unit.

CSU. Channel service unit; customer setup.

EDS. Extended data stream.

HPCA. High-performance communications adapter.

ACTPU. Activate physical unit.

CSW. Channel status word.

EFCA. Extended field and character attribute.

HVPS. High-voltage power supply.

AID. Attention identification.

CTS. Clear to Send (CCITT 106),

EIA. Electronic Industries Association.

APL. A programming language.

CU. Control unit.

EM. End of message.

ASCII. American Standard Code for Information Interchange.

CUE. Control unit end.

ENQ. Enquiry.

I. Information (format).
IC. I nsert cursor.
EOF. End of field.

IML. Initial machine load.
EOI. End of inquiry.

B. Busy

DACTLU. Deactivate logical unit.

I/O. Input/output.
EOR. End of record.

BB. Begin bracket.

DACTPU. Deactivate physical unit.

Ind. Indicator.
EOT. End of transmission.

BCC. Block check character.

DB. Device busy.

IR. Intervention required.
EP. Emulator program.

BOC. Bus out check.

DC. Device check.

ITB. Intermediate transmission block.
ERP. Error recovery procedure.

BSC. Binary synchronous communication.

DCA. Device cluster adapter.

BTDAT. Buffered teleprocessing diagnostic analyzer and tester.

DCB. Device control block.

BTU. Basic transmission unit.

DCE. Data communication equipment.

ESC. Escape.

ETB. End of transmission block.

LCA. Local channel attachment (Model A).

ETX. End of text.

LCID. Local character set identifier.

EUA. Erase unprotected to address.

LED. light-emitting diode.

EX. Exception (response).

LF. line feed.

DDS. Digital Data Service.
DE. Device end.

C. Control field.
DFC. Data flow control.
CAW. Channel address worp.

LHA. Local host attachment (Model B).
DISC. Disconnect.

CC. Control check.

LIC. Last in chain.
DLC. Data lengt.h check.

F. SDLC flag pattern.

OLE. Data link escape.

FCS. Frame check sequence.

OM. Disconnect mode.

FF. Forms feed.

CCITT. Consultative Committee on International Telephone
and Telegraph.

D/R. Driver/receiver.

Fl. Format indicator.

CCW. Channel control word.

DSR. Data Set Ready (CCITT 107).

FM. Field mark; function management.

CD. Change direction.

DUP. Duplicate.

FRMR. Frame reject.

CCA. Common communications adapter.

LRC. Longitudinal redundancy check.
LU. Logical unit.

CCC. Copy control character.

LUST AT. Logical unit status.
LVPS. Low·voltage power supply.

CDS. Configuration data set.

FRU. Field replaceable unit.

M
MCM. Maintenance concepts manual.

E
MDT. Modified data tag.

CEo Channel end.

EAU. Erase all unprotected.
CMDR. Command reject.

MES. Miscellaneous equipment specification.
EB. End brackets.

GP. General poll.
MHS. Magnetic hand scanner.

CPU. Central processing unit.
EBCDIC. Extended binary-coded-decimal interchange code.
CR. Command reject; carriage return.

MIM. Maintenance information manual.
EC. Equipment check.

CRC. Cyclic redundancy check.

SV27-2512-3

D·1

SY27-2512-3

0-2

MSG. Message.

PS. Programmed symbol.

SIM. Set initialization mode.

MSR. Magnetic slot reader.

PT. Program tab.

SIOF. Start I/O fast release.

PU. Physical unit.

SLHA. Simplified local host attachment (Model D).

N
NA. Not applicable.

SLU. Secondary logic unit.
SM. Status modifier.

NAK. Negative acknowledgement.

RA. Repeat to address.

NCCF. Network Communications Control Facility.

Rd Mod. Read modified.

NCP. Network control program.

RECFMS. Record formatted maintenance statistics.

NOM. Normal disconnected mode.

Req. Request.

NI. Not initialized.

REaMS. Request maintenance facility.

NL. New line.

RH. Request/response header.

NOP. No operation.

RIM .• Request initialization.

Nr. Next sequence number expected to arrive.

RLSO. Received Line Signal Detector (CCITT 109),

NRM. Normal response mode.

RNR. Request not ready.

NRZI. Zero-complemented differential coding (non-return-to-zero
inverted) .

ROL. Request online status.

SNA. Systems network architecture.
SNRM. Set normal response mode.
SOH. Start of heading.
SP. Space; specific poll.
SSC. Subsystem support center.
SSCP. System services control point.
STX. Start of text.
SYN. Synchronous idle.

ROI. Request initialization.

TC. Transmission check.

RR. Receive ready.

TH. Transmission header.

RSOR. Read start old receive.

TP. Teleprocessing.

RSP. Response.

TPLM. Teleprocessing line monitor.

RTR. Ready to receive.

TTO. Temporary text delay.

Ns. Transmitter's sequence number.
NS. Nonsequenced format (C-field).
NSA. Nonsequenced acknowledgement.
NSI. Nonsequenced information.
NUL. Null.
RTS. Request to send.

u
RU. Request/response unit.
UA. Unnumbered acknowledge.

OAF. Origin address field.

RVI. Reverse interruption.
UC. Unit check.

~C.

Operation check.

UCW. Unit control word.

OL T. Online test.
S. Sequenced (format).

UE. Unit exception.

SBA. Set buffer address.

UI. Unnumbered informational.

P. Printed; protected.

SC. Session control.

US. Unit specify.

PC. Printed circuit.

SOLC. Synchronous data link control.

PCM. Purity check modifier.

SOT. Start data traffic.

P/F. Poll/final bit.

SERDES. Serializer/deserializer.

PIU. Pilth information unit.

SF. Start field.

PLU. Primary logic unit.

SFAP. Structured field and attribute processing.

POR. Power on reset.

SI. Suppress index.

w
WACK. Wait before transmit.
WCC. Write control character.
WSF. Write structured field.

x
XID. Exchange station identification.

3274 Control Unit Models lA, lB, lC, lD, 21A, 21B, 21C, 21D, 31A, 31C and 31D Maintenance Concepts Printed in U.S.A. SY27-2512-3

--------------

----

-----------.
------ --International Business Machines Corporation
Data Processing Division
1133 Westchester Avenue, White Plains, N.Y. 10604
IBM World Trade Americas/Far East Corporation
Town of Mount Pleasant. Route 9, North Tarrytown, N.Y., U.S.A. 10591
IBM World Trade Europe/Middle East/ Africa Corporation
360 Hamilton Avenue, White Plains. N.Y., U.S.A. 10601

IYIVUt;OlO)

1'-",

lU,

Iv,

IU,LIM/LIO,Llv,t&.IIJ/uIM,~lv~IU~IU

Maintenance Concepts

..;

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Order No. SY27-2512~3

Order No. SY27-2512-3

This manual is part of a library that serves as a reference source for systems analysts, programmers, and
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Comments may be written in your own language; use of English is not required.
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Models 1A, 1 B, le, 1 D, 21 A, :N 8,21 C,021 0,31 A, 31 C and 310
Maintenance Concepts

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