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EK-DMVQM-UG-003

August 1988

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Document:	QMA DMV11 Synchronous Controller User's Guide
Order Number:	EK-DMVQM-UG
Revision:	003
Pages:	203
Original Filename:	http://bitsavers.org/pdf/dec/qbus/EK-DMVQM-UG-003_Aug88.pdf

OCR Text

EK-DMVQM-UG-003

QMADMV11
Synchronous Controller
User's Guide

EK-DMVQM-UG-003

QMA DMV11

Synchronous Controller
User's Guide

Prepared by Educational Services
of
Digital Equipment Corporation

1st Edition, January 1984
2nd Edition, November 1986
3rd Edition, August 1988

The information in this document is subject to change without notice and should
not be construed as a commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any errors that may
appear in this document.

Printed in U. S.A.

This document was set on a DIGITAL DEeset Integrated Publishing System. Book production was done by Educational Services Development and
Publishing in Merrimack, N.H.
•

Class A Computing Devices:

Notice: This equipment generates, uses, and may emit radio frequency energy.
The equipment has been type tested and found to comply with the limits for a
Class A computing device pursuant to SubpartJ of Part 15 of FCC Rules, which
are designed to provide reasonable protection against such radio frequency interference
when operated in a commercial environment. Operation of this equipment in a
residential area may cause interference in which case the user at his own
expense may be required to take measures to correct the interference.
The following are trademarks of Digital Equipment Corporation:

~DmDDmD

DEC
DECmate
DECset
DECsystem-lO
DECSYSTEM-20
DECUS

DECwriter
DIBOL
MASSBUS
PDP

P/OS
Professional
Rainbow
RSTS

RSX
Scholar
ULTRIX
UNIBUS
VAX
VMS
VT
Work Processor

CONTENTS
Page

PREFACE
CHAPTER 1

INTRODUCTION

1.1
1.2
1.3
1.4
1.5
1.6
1.6.1
1.6.2
1.7
1.7.1
1.7.2
1.7.3
1.8
1.8.1
1.8.2
1.8.3

INTRODUCTION .................................................................................................... 1-1
INTRODUCTION TO MULTIPOINT .................................................................... 1-1
DMV11 GENERAL·DESCRIPTION ..................................................................... 1-1
STANDARD APPLICATIONS ............................................................................... 1-3
DMV11 SYSTEM OPERATION ............................................................................ 1-3
COMMAND/RESPONSE STRUCTURES ........................................................... 1-5
Input Commands ................................................................................................... 1-5
Output Responses .................................................................................................. 1-5
PROTOCOL SUPPORT ........................................................................................... 1-5
Data Messages ....................................................................................................... 1-7
Control Messages ................................................................................................... 1-7
Maintenance Messages .......................................................................................... 1-7
GENERAL SPECIFICATIONS .............................................................................. 1-7
Environmental Specifications ................................................................................ 1-7
Electrical Specifications ........................................................................................ 1-8
Performance Specifications ................................................................................... 1-8

CHAPTER 2

INSTALLATION

2.1
2.2
2.3
2.4
2.4.1
2.4.2
2.5
2.6
2.6.1
2.6.2
2.6.3
2.6.4
2.6.5
2.7
2.7.1
2.7.2
2.8
2.8.1
2.8.2
2.8.3
2.8.4
2.8.5

INTRODUCTION .................................................................................................... 2-1
UNPACKING AND INSPECTION ....................................................................... 2-1
INSTALLATION CONSIDERATIONS ................................................................. 2-1
PREINSTALLATION CONSIDERATIONS .......................................................... 2-1
Device Placement ................................................................................................. 2-5
System Requirements ............................................................................................ 2-5
INSTALLATION ...................................................................................................... 2-9
DMV 11 SYSTEM TESTING ................................................................................ 2-41
Functional Diagnostic Testing ............................................................................. 2-41
DEC/XII System Exerciser .............................................................................. 2-41
Final Cable Connections ...................................................................................... 2-41
DMV11 Link Testing ......................................................................................... 2-41
MDM Diagnostics ............................................................................................... 2-41
DMV11-SF SYNCHRONOUS INTERFACE OPTION ....................................... 2-42
BA200 Series System Enclosures ....................................................................... 2-43
~iodule Differences ............................................................................................. 2-44
INSTALLATION .................................................................................................... 2-44
Unpacking the Option Kit .................................................................................. 2-44
Inspecting the FCC and EOS Clips ................................................................... 2-45
Software Backup ................................................................................................. 2-46
Configuration ...................................................................................................... 2-46
Checking the System Configuration ................................................................... 2..;46

111

CONTENTS (Cont)
Page

2.8.6
2.8.6.1
2.8.6.2
2.8.6.3
2.8.7
2.8.7.2
2.8.8
2.9
2.10
2.11
2.11.1
2.11.2
2.12
2.13
2.14

Guidelines for Module Placement ....................................................................... 2-49
Bus Continuity ............................................................................................... 2-49
Power Supplies ............................................................................................... 2-49
DMVII-SA Bus Priority ............................................................................... 2-50
Finding CSR Addresses and Interrupt Vectors ................................................... 2-50
MicroVAX Systems ........................................................................................ 2-50
Configuring the DMVII-SF Option ................................................................... 2-52
OPERATING SYSTEM SOFTWARE SHUTDOWN ......................................... 2-53
TESTING THE SYSTEM ..................................................................................... 2-53
RELOCATING EXISTING MODULES .............................................................. 2-53
Modules with Handles ......................................................................................... 2-53
Modules with Blank Covers ................................................................................ 2-56
VERIFYING THE GROUND CONNECTIONS ................................................ 2-56
INSTALLING THE DMVII MODULE .............................................................. 2-60
CONNECTING EXTERNAL DEVICES ............................................................ 2-60

CHAPTER 3

COMMAND AND RESPONSE STRUCTURES

3.1
3.2
3.2.1
3.2.2
3.2.3
3.3
3.3.1
3.3.2
3.3.3
3.3.4
3.4
3.4.1
3.4.2
3.4.3
3.5

INTRODUCTION .................................................................................................... 3-1
COMMAND STRUCTURE .................................................................................... 3-1
Control and Status Registers ................................................................................ 3-1
Input Commands Overview ................................................................................... 3-5
Output Responses Overview .................................................................................. 3-5
DMV 11 INPUT COMMANDS ............................................................................... 3-6
Microprocessor Control/Maintenance Command .................................................. 3-6
Mode Definition Command .................................................................................. 3-6
Con trol Command ................................................................................................. 3-9
Buffer Address/Character Count (BA/CC) Command ..................................... 3-16
DMV 11 OUTPUT RESPONSES .......................................................................... 3-18
Buffer Disposition Response ............................................................................... 3-19
Control Response ................................................................................................. 3-20
Information Response .......................................................................................... 3-26
TSS/GSS ACCESS ................................................................................................. 3-26

CHAPTER 4

PROGRAMMING TECHNIQUES

4.1
4.2
4.2.1
4.2.2
4.2.3
4.3
4.3.1
4.3.2
4.3.2.1
4.3.2.2
4.3.3

INTRODUCTION .................................................................................................... 4-1
COMMAND/RESPONSE DISCIPLINE AND HANDSHAKING ..................... 4-1
Command Discipline ............................................................................................. 4-2
Retrieving Responses ............................................................................................. 4-3
CSR Interface Interactions ................................................................................... 4-3
DMV11 START-UP ................................................................................................. 4-3
Configuration Procedure ....................................................................................... 4-4
Specifying User-Defined Parameters .................................................................... 4-4
Specifying TSS Parameters ............................................................................. 4-6
Specifying (JSS Parameters ........................................................................... 4-11
Protocol Operation .............................................................................................. 4-1 3

CONTENTS (Cont)
Page

4.4.1
4.4.2
4.4.3
4.5
4.5.1
4.5.2
4.6
4.6.l
4.6.1.1
4.6.1.2
4.6.2
4.6.2.1
4.6.2.2
4.6.2.3
4.7
4.7.1
4.7.2
4.7.3
4.7.4
4.7.4.1
4.7.4.2
4.7.4.3
4.8

CRITERIA FOR DETERMINING COMMUNICATIONS LINK
PARAMETERS ....................................................................................................... 4-13
Setting the Selection Interval Timer ................................................................... 4-14
Setting the Babbling Tributary Timer ................................................................ 4-16
Setting the Streaming Tributary Timer .............................................................. 4-16
ERROR COUNTER ACCESS .............................................................................. 4-17
Reading the Counters .......................................................................................... 4-17
Counter Skew........................................................ ,............................................. 4-17
ERROR RECOVERY PROCEDURES ................................................................ 4-17
Recovery from Network Errors ............................ '" ...... ,.... ,............................... 4-18
Recovery from Threshold Errors .................................................................... 4-18
Recovery from Babbling and Streaming Tributary Errors ............................ 4-18
Recovery from Procedural Errors ....................................................................... 4-18
Recovery from a Nonexistent Memory Error ................................................ 4-18
Recovery from a Receive Buffer Too Small Error ........................................ 4-19
Recovery from a Queue Overflow Error ....................................................... 4-20
4-20
BOOTING A REMOTE STATION ...............
Steps Leading to a Remote Load Detect Boot. .................................................. 4-21
Steps Leading to a Power-On Boot. .................................................................... 4-21
Steps Leading to an Invoke Primary MOP Boot. ............................................... 4-22
DMV11 Switch Settings for the Boot Functions ................................................ 4-22
Switch Settings for the Power-On Boot Function .......................................... 4-22
Switch Settings for the Invoke Primary MOP Boot Function ....................... 4-22
Switch Settings for the Remote Load Detect Boot Function ........................ 4-23
MAINTENANCE REGISTER EMULATION .................................................... 4-23

CHAPTER 5

ASPECTS OF DMVll MICROCODE OPERATION

5.1
5.2
5.2.1
5.2.2
5.2.2.1
5.2.2.2
5.2.2.3
5.2.2.4
5.3
5.3.1
5.3.1.1
5.3.1.2
5.3.1.3
5.3.1.4
5.3.1.5
5.3.1.6
5.3.1.7
5.3.1.8
5.3.1.9
5.3.1.10

INTRODUCTION .................................................................................................... 5-1
DMV11 POLLING ALGORITHM .......................................................................... 5-1
Calculating Polling Urgency .................................................................................. 5-2
Criteria for Determining Polling Parameters ........................................................ 5-6
Determining a Value for DELTA T ................................................................ 5-6
Determining Values for Q and R ............... ,............. ,........................... ,.......... 5-7
Determining a Value for Poll Delay ................................................................ 5-8
Determining a Value for DEAD T .................................................................. 5-8
ERROR COUNTERS .............................................................................................. 5-8
Data Link Error Counters ................................................................................... , 5-9
Data Errors Outbound ..................................................................................... 5-9
Data Errors Inbound ...................................................................................... 5-11
Local Reply Timeouts .................................................................................... 5-11
Remote Reply Timeouts ................................................................................. 5-11
Local Buffer Errors ....................................................................................... 5-12
Remote Buffer Errors .................................................................................... 5-12
Selection Timeouts ......................................................................................... 5-12
Data Messages Transmitted ........................................................................... 5-12
Data Messages Received ................................................................................ 5-12
Selection Intervals .......................................................................................... 5-13

4.4

00 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •

CONTENTS (Cont)
Page
5.3.2
5.3.2.1
5.3.2.2
5.3.2.3
5.3.2.4
5.3.3
5.3.3.1
5.3.3.2
5.3.3.3
5.4
5.4.1
5.4.1.1
5.4.1.2
5.4.1.3
5.4.2
5.4.3
5.4.3.1
5.4.3.2

Station Error Counters ........................................................................................ 5-13
Remote Station Errors ................................................................................... 5-13
Local Station Errors ....................................................................................... 5-13
Global Header Block-Check Errors ............................................................... 5-14
Maintenance Data Field Block-Check Errors ................................................ 5-14
Threshold Error Counters ................................................................................... 5-14
Transmit Threshold Errors ...................................................................... ,...... 5-14
Receive Threshold Errors ............................................................................... 5-15
Selection Threshold Errors ............................................................................. 5-15
DMV11 MICROCODE INTERNAL DATA BASE OVERVIEW ....................... 5-15
Linked Lists ........................................................................................................ 5-15
The Free Linked List ..................................................................................... 5-16
The Response Linked List ............................................................................. 5-18
Buffer Linked Lists ....................................................................................... 5-18
Slot Mapping Table ............................................................................................. 5-19
TSS and GSS Structures .................................................................................... 5-19
The Global Status Slot (GSS) ....................................................................... 5-19
Tributary Status Slots (TSS) ......................................................................... 5-19

APPENDIX A

DDCMP

A.1
A.1.I
A.1.2
A.1.3
A.1.4
A.1.5
A.2
A.3

DDCMP .................................................................................................................... A-I
Controlling Data Transfers ................................................................................... A-I
Error Checking and Recovery .............................................................................. A-I
Character Coding ................................................................................................. A-2
Data Transparency ............................................................................................... A-2
Data Channel Utilization ..................................................................................... A-2
PROTOCOL DESCRIPTION ................................................................................. A-2
MESSAGE FORMAT ............................................................................................. A-4

APPENDIX B

FLOATING DEVICE CSR AND INTERRUPT VECTOR ADDRESSES

B.1
B.2
B.3

FLOATING DEVICE CSR ADDRESSES .............................................................. B-1
FLOATING INTERRUPT VECTOR ADDRESSES ............................................. B-4
EXAMPLES OF DEVICE CSR AND INTERRUPT VECTOR ADDRESS
ASSIGNMENT ........................................................................................................ B-6

APPENDIX C

MODEM CONTROL REGISTER FORMATS

C.1
C.2

MODEM CONTROL REGISTER FORMATS ..................................................... C-I
RS-449 VERSUS RS-232-C .................................................................................... C-4

CONTENTS (Coot)
Page
APPENDIX D

MODEM CONTROL

0.1
0.1.1
0.1.2

MODEM CONTROL ............................................................................................... 0-1
Hardware Modem Control ................................................................................... 0-1
Modem Control Implemented by the DMV11 Microcode ................................... 0-1

APPENDIX E

QMA DMVII OPTION CONFIGURATIONS

E.l

INTRODUCTION .................................................................................................... E-1
OPTION DESIGNATION CONVERSION ............................................................ E-1
Installed Option ..................................................................................................... E-1
Add-On Option ..................................................................................................... E-1
Base Options .................................................................................................... E-1
Cabinet Kits ..................................................................................................... E-1
OPTION CONFIGURATION SUMMARY ........................................................... E-1
Base Option Designations ...................................................................................... E-3
Cabinet Kit Designations ...................................................................................... E-3
DMV11 OPTION CONFIGURATIONS ................................................................. E-5

E.2
E.2.1
E.2.2
E.2.2.1
E.2.2.2
E.3
E.3.1
E.3.2
E.4

FIGURES
Figure No.
1-1
1-2
1-3
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
2-14
2-15
2-16
2-17
2-18
2-19
2-20

Title

Page

DMV11s Used in Point-to-Point Applications ............................................................ 1-3
DMV 11 s Used in Multipoint Applications ................................................................. 1-4
General Summary of DMV 11 Command/Response Structure .................................. 1-6
Local Network Topology ............................................................................................. 2-2
Remote Network Topology ......................................................................................... 2-3
M8053 Switch Locations ............................................................................................ 2-7
M8064 Switch Locations ............................................................................................ 2-8
DMV11 Installation Flow .......................................................................................... 2-12
DMV 11 Switch Selectable Features .......................................... ,.............................. 2-15
Test Connector Insertion for the M8053 ................................................................... 2-19
Test Connector Insertion for the M8064 ................................................................... 2-20
DMVl1 Test Connectors ........................................................................................... 2-21
DMVl1 Cable Drawings ........................................................................................... 2-25
DMV11 Non-FCC Compliant Cable Drawings ........................................................ 2-28
DMV11 Remote System Cabling Diagram .............................................................. 2-30
DMV11 to DMVl1 Integral (Local) Modem Cabling Diagram (Point-to-Point} ..... 2-32
Half-Duplex Multipoint Network (Control Station End Node} ................................. 2-34
Full-Duplex Multipoint Network (Control Station End Node} .................................. 2-35
Full-Duplex Multipoint Network (Control Station Inner Node} ................................ 2-36
DMV11 Cabinet Installation to FCC Bulkhead ....................................................... 2-37
DMV11 to RS-232-C Interface Panel (70-20863) .................................................... 2-38
DMV11-SA Module (M8053-PA) with Bulkhead Handle ........................................ 2-42
BA220 Series Enclosure Chassis ............................................................................... 2-43

FIGURES (Cont)
Page

2-21
2-22
2-23
2-24
2-25
2-26
2-27
2-28
2-29
2-30
2-31
2-32
2-33
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
4-1
4-2
4-3
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
A-I
A-2
B-1
D-l
D-2
D-3
D-4
D-5
D-6
D-7
D-8

DMV II-SF Option Kit Contents .............. ,....... '" ...... '" ............................................ 2-45
FCC and EOS Clips ................................................................................................. 2-46
BA200 Series Configuration Worksheet .................................................................... 2-47
Bus Grant Continuity Path ....................................................................................... 2-49
M8053-PA Module Layout ....................................................................................... 2-52
Releasing the Captive Screws ................................................................................... 2-54
Unlocking the Release Levers ................................................................................... 2-55
Removing the Blank Cover ....................................................................................... 2-57
Ground Connections .................................................................................................. 2-58
Attaching the Gap Filler Assembly .......................................................................... 2-59
Inserting the Module ................................................................................................. 2-61
Cable Option Attachment ........................ '" .............................................................. 2-62
DMVII-SF Cable Connections ................................................................................. 2-63
DMVII CSRs Byte and Word Symbolic Addresses .................................................. 3-2
Fixed and Variable Formats for Commands and Responses ....................................... 3-2
Microprocessor Control/Maintenance Command Format. ........................................... 3-6
Initialization of the DMVII ....................................................................................... 3-7
Mode Definition Command Format ............................................................................ 3-8
Control Command Format .......................................................................................... 3-9
Buffer Address/Character Count Command Format ............................................... 3-17
Buffer Disposition Response Format ......................................................................... 3-19
Control-Out Command Format ................................................................................. 3-26
Information Response Format ................................................................................... 3-27
CSR Interface Control Bits ......................................................................................... 4-2
CSR Access Window .................................................................................................. 4-4
DMVII Maintenance Loop Command Format ........................................................ 4-24
Interrelationship Between Polling Parameters Q, R, and DELTA T .......................... 5-3
Relationship Between Polling Parameters Q, R, and the Minimum Polling Interval ...... 5-4
Relationship Between the Default Values for Q and R for the Three
Polling Activity Levels ................................................................................................ 5-5
State Diagram of Polling State Transitions ................................................................. 5-7
Data Link and Threshold Error Counters ................................................................. 5-10
Station Error Counters .............................................................................................. 5-11
Data Memory Map ................................................................................................... 5-16
DMV 11 Linked List Structure Format.. .................................... '" ............................ 5-17
Standard Link Block ................................................................................................. 5-18
Global Status Slot ..................................................................................................... 5-21
Tributary Status Slot ................................................................................................. 5-23
DDCMP Data Message Format ................................................................................. A-I
DDCMP Message Format in DetaiL ......................................................................... A-3
UNIBUS and LSI-II Address Map ........................................................................... B-2
Flow Diagram Symbology .......................................................................................... D-4
Modem Control (Start) ............................................................................................... D-5
Modem Control (Transmit) ........................................................................................ D-6
Modem Control (Transmit 2) ..................................................................................... D-7
Modem Control (Receive) ........................................................................................... D-8
Modem Control (Modem Status) ................................................................................ D-9
Modem Control (Call Timer) ................................................................................... D-l 0
Modem Control (Shutdown) ..................................................................................... D-ll

Vlll

FIGURES (Cont)
Page
E-l
E-2

Base Option Designation ............................................................................................. E-3
Cabinet Kit Designation .............................................................................................. E-4

TABLES
Table No.
1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-10
2-11
2-12
2-13
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
4-1
4-2
4-3
4-4
4-5
4-6
B-1
B-2
D-1
E-1
E-2
E-3
E-4

Title

Page

DMVll Options .......................................................................................................... 1-2
Typical Host Options of a Bell 208A™ Data Set (4800 b/s) Full-Duplex
Operation ..................................................................................................................... 2-4
Typical Tributary Options of a Bell 208A™ Data Set (4800 b/s) Full-Duplex
Operation ..................................................................................................................... 2-4
DMV 11 Voltage Chart ...................................... ,......................................................... 2-6
Device Address Selection .......................................................................................... 2-10
Vector Address Selection ........................................................................................... 2-11
DMV11 EI01 (M8053)/EI07 (M8064) Switch Selectable Features ...................... 2-16
Cabinet Kits .............................................................................................................. 2-18
Switch Function Settings on 70-20863 Panel for RS-232-C Interface ..................... 2-39
BC55H Jumper Modem Functions ............................................................................ 2-40
Power and Bus Load Data ........................................................................................ 2-48
Recommended Module Order .................................................................................... 2-50
Devices Supported by SYSGEN .............................................................................. 2-51
Extension Cables ....................................................................................................... 2-62
SELO Bit Functions ..................................................................................................... 3-2
BSEL2 Bit Functions .................................................................................................. 3-4
Input Command Codes ................................................................................................ 3-5
Mode Field Codes and Functions ................................................................................ 3-8
SEL6 Control Command Functions .......................................................................... 3-10
Request Key Field Definitions (Control Command) ................................................. 3-14
Output Codes (BSEL6) ............................................................................................. 3-21
Return Keys for Information Response ..................................................................... 3-27
Diagnostic Error Codes ............................................................................................... 4-5
U ser-Defined TSS Parameters .................................................................................... 4-7
User-Defined GSS Parameters ................................................................................. 4-12
Recommended Selection Interval Timer Values ........................................................ 4-15
Mode Switch Settings ............................................................................................... 4-23
Maintenance Command Functions BSEL2 Bits 0-3 .................................................. 4-25
Floating Device CSR Address Assignments ............................................................... B-3
Floating Interrupt Vector Address Assignments ......................................................... B-4
DMVll Modem Control Functions ............................................................................ D-2
Option Compatibility Cross-Reference ........................................................................ E-2
Electrical and Mechanical Interface Type .................................................................. E-3
Cabinet Kit Components ............................................................................................. E-4
DMV11 Option Configurations ................................................................................... E-5

PREFACE

The Qualified Modular Assembly (QMA) DMVl1 Synchronous Controller has been tested and meets all
requirements for limiting electromagnetic interference.
This manual has been written to meet the needs of Field Service personnel and contains the following
categories of information:
•

General description including features, specifications, and functional descriptions,

•

Installation,

•

Command and response structures,

•

Programming, and

•

Microcode operation.

This manual also includes appendices that discuss DDCMP, floating device and vector addresses, modem
control register formats, modem control, and the QMA DMV 11 options and cabinet kits.

NOTE
In this manual, the QMA DMVll Synchronous
Controller is referred to as the DMVll for brevity.

CHAPTER 1
INTRODUCTION

1.1

INTRODUCTION

The multipoint DDCMP-DMV 11 Intelligent Communications Synchronous Line Controller is a device
which provides elficient high-speed synchronous communications for distributed networks. The DMV 11
uses LSI-II CPUs as control or tributary stations, while requiring a minimum of main CPU resources.
This manual provides detailed information necessary for installing and operating the DMV 11.

1.2 INTRODUCTION TO MULTIPOINT
Point-to-point configurations are practical when the message rate of the terminals is high. In many cases,
however, the message rate of the terminals is very low even though the bit rate may be quite high. In these
cases, sharing a transmission line can significantly reduce the cost and improve the efficiency of a
communications network.
Various techniques are used to share transmission lines to improve their utilization. One of these techniques is the use of multipoint lines. In multipoint operation, a single line can be shared among many
nodes. Each node is a station and has a unique address. One station in the network is always designated as
the control station while the remaining stations are designated as tributary stations. Because all stations are
connected to the same line, no two tributary stations may transmit at the same time, and each station must
have a means of recognizing which messages it is meant to receive. The address field of the message
header identifies the station to receive the message. The control station governs sharing of the line by
means of polling in order to authorize transmission to the control station. In a polling operation the
tributaries are in effect asked one by one whether they have anything to transmit. To accomplish this, the
control station sends a polling message with a unique tributary address down the line. The station which
recognizes the address responds by sending data or by sending a positive response.
Tributary stations can only transmit to the control station and only in response to a polling message from
the control station. Transmission between tributaries is not allowed as all message traffic must be routed
through the control station. Control stations on the other hand may transmit to any tributary at any time if
the communicating stations are in full-duplex. In fact, multiple messages for different destinations
(tributaries) can be sent serially by the control station. Each tributary station then, in turn, examines the
address and accepts only those messages it is meant to receive.
The use of communication lines can be maximized by using full-duplex capabilities at the control station to
accommodate many tributary stations on a full-duplex line. In this mode, the control station keeps the lines
full by sending to one or more tributary stations, while at the same time receiving from another tributary
station.

1.3

DMVll GENERAL DESCRIPTION

The DMV 11 is a high-performance line controller which operates at speeds up to 56K b/s. It accomplishes
this by doing DMA transfers.
The available options are listed in Table 1-1.

1-1

Table 1-1
Base Option and
Cabinet Kit*

DMVll Options

Interface

Line Speed

EIA RS-232-C

Up to 19.2K b/s

CCITT V.35

Up to 56K b/s

Integral modem

56K b/s only

EIA RS-423-A/449

Up to 56K b/s

DMVII-M
+CK-DMVII-Ax
DMVII-M
+CK-DMVI1-Bx
DMVII-N
+CK-DMVII-Cx
DMVII-M
+CK-DMVII-Fx

NOTE:
Refer to Appendix E, Table E-l, for old/new option designation cross-reference
(that is, non-FCC compliant/FCC compliant).
*x = A, B, C, or F as applicable.

Features of the DMV 11 include:
•

Support of point-to-point and multipoint operation,

•

Support for remote or local, full-duplex, or half-duplex configurations,

•

Support for 12 tributaries and one control station in multipoint operation,

•

Switch and program selectable operating mode and tributary address,

•

Support for multiple addressed tributaries,

•

Down-line loading and remote load detect capabilities,

•

Go/No-Go diagnostic testing by the microcode,

•

Go/No-Go extensive error reporting.

•

Modem control.

1-2

1.4 STANDARD APPLICATIONS
The DMVII can be used with the integral modem as well as with EIA and CCITT applications. These
applications can be configured as either point-to-point or multipoint networks. Figure 1-1 shows a typical
point-to-point applic:ation and Figure 1-2 shows a typical multipoint application. For local operations
through integral modems, stations are interconnected by twinax or triaxial cables. The integral modem can
support up to 12 drops in both half- and full-duplex modes. For remote operations, stations are connected
through external modems that use common carrier facilities. For specific information on installation of
either of the basic DMV 11 units and associated options, refer to Chapter 2.

LSI-11 CPU

LOCAL
NODE

OPERATING
SYSTEM
USER PROGRAM
DEVICE DRIVER

OPERATING
SYSTEM
USER PROG RAM
DEVICE DRIVER

LSI-ll BUt:>

REMOTE
NODE
lSI-ll BUt:>

TRIB.

r----,
r----,
: MODEM :1oiI4------{.S S
...---,l.~1 MODEM I

L___ J

L ___ ~

DMV11

#12
DMV11
MK-2485

Figure 1-1

DMVIIs Used in Point-to-Point Applications

For multipoint applications, the tributary address for each DMV 11 in the network is either switch or
program assigned. In the case of switch-assigned tributary addresses, specific switches on each DMV 11
define the numerical value of the address to which that DMVII responds. The advantage of a switchassigned tributary address is that it provides data transfer security since the address cannot be changed by
software.
A major advantage of DMV 11 multipoint networks is the ability of the main CPU at the control station to
down-line load programs to the CPU at each tributary and start those programs without manual intervention. As a result, DMV II-based multipoint networks are particularly suited for installation at remote and
generally inaccessible locations. For example, DMV 11 s may be used in remote systems, in hard to reach
locations such as weather stations at sea, and in hazardous environments.

1.5

DMVll SYSTEM OPERATION

Operation of the DMV 11 communications line controller is initiated and directed by a user program
residing in the main memory. The user program consists of an application program and a device driver
that serves as an interface between the DMVII and the CPU.
Communication between the user program and the DMV 11 is accomplished over the LSI-II bus through
four control and status registers (CSRs). These four 16-bit registers serve as a bidirectional port to pass
user-program commands to the DMV 11, and DMV 11 responses to those commands back to the user
program. Each of these registers are word and byte addressable by both the user program and the DMV 11
microcode.

1-3

LSI·11 CPU

OPERATING
SYSTEM

USiER PROGRAM
DEVICE DRIVER

DMV11
CONTROL
STATION
(INTERNAL
DATA
STRUCTURE)

LSI·"

BUQ
TRIBUTARY
STATUS SLOTS

#2
#1

}

...!.L..
#4

#12

r---'

I MODEM I

r---,

: MODEM

L __ ...J

DMV11
MULTIPOINT
NODE A
OPERATING
SYSTEM
USER PROGRAM/
DEVICE DRIVER

r---,

L _ _ --'

#1
STATUS SLOT
FOR SWITCH
SET TRIB.
ADORE S
~

DMV11
MULTIPOINT
NODE B

#2
#3}
#4

.-~:~

OPERATING
SYSTEM

•
#n

VSER PROGRAMI

LSI-11 B~ ~_D_E_V_IC_E_D_R_I_V_ER_ _...

LSI·1'

TRIB/STATUS
SLOTS FOR
MULTIADDRESS
STATION
MULTIPOINT
NODE C

I
I

MODEM I

L __ ...JI

DMV11

OPERATING
SYSTEM

USER PROGRAMI
DEVICE DRIVER

LSI·"

BV
MK-2520

Figure 1-2

DMV lIs Used in Multipoint Applications

NOTE
Normally only four CSRs are available to the user
program. However, in 22-bit address mode, eight
CSRs are available although only one additional 16bit register is used.
In this group of four CSRs, the first two have a fixed format and in general serve as a handshake control
for user-program commands and DMV 11 responses. The next two CSRs form a port for the exchange of
commands and responses between the user program and the DMV 11. Other control fields provide for
initialization, interrupt enabling, reading and execution of maintenance instructions, data transfer setup,
and tributary addressing.
A user program issues a command to the DMVl1 by first requesting the use of the data port. When the
DMV 11 grants permission to use the data port, the user program passes the command to the DMV 11 in
the CSRs. The DMV 11 interprets the command and performs the specified actions. If a response is
required, the DMV 11 stores the appropriate response in the CSRs and then informs the user program that
a response is present.
Message data received or to be transmitted by the DMV 11 is written into or read from preassigned buffers
in main CPU memory. These buffers are accessed by the DMVII through nonprocessor requests (NPRs)
to the associated bus address.
1.6 COMMAND/RESPONSE STRUCTURES
Since the DMV 11 is basically an input/output device, it follows that the command/response set for this
device be categorized as input commands and output responses. Input commands are commands issued by
the user program to the DMV 11. Output responses are typically responses to those commands, and are
issued by the DMV 11 to the user program.
Some responses are unsolicited, and are used to inform the user program of protocol events and line errors.
1.6.1 Input Commands
There are four types of input commands. They are listed below in the usual order of issuance.
1.
2.
3.
4.

Microprocessor control/maintenance,
Mode definition,
Control,
Buffer address/character count.

1.6.2 Output Responses
Output responses serve to inform the user program of normal or abnormal conditions concerning the data
transfer operation. There are three types of output responses:
1.
2.
3.

Control response,
Information response,
Buffer disposition response.

Figure 1-3 is a general summary of the functions performed by the DMV 11 command/response structure.
These commands and responses are discussed in detail in Chapter 3.
1.7 PROTOCOL SUPPORT
In DMV 11 point-to-point and multipoint networks, all message transfers between nodes are under control
of the Digital Data Communications Message Protocol (DDCMP). All aspects of DDCMP processing are
handled by the DMV 11 microcode. Message handling at the user-program level only involves setting up
data buffers during transmit operations and accepting data from the DMV 11 during receive operations.

1-5

LSI-11
USER PROGRAM

USER PROGRAM ISSUES
MICROPROCESSOR CONTROL
COMMAND TO MASTER
CLEAR DMV11

INITIALIZE
DMV11

NOTIFY
USER
PROGRAM

FAILURE

USER
PROG. VERIFIES
INTERNAL
DIAG.

SUCCESSFUL,
DMV11 RUNNING
SET MODE OF HALFOR FULL-DUPLEX,
ESTABLISH STATION
AS POINT-TO-POINT
NODE OR MULTIPOINT
CONTROL OR TRIBUTARY
STATION

USER PROGRAM ISSUES
MODE DEFINITION
COMMAND

ESTABLISH TRIBUTARIES,
SET USER DEFINED
PARAMETERS, INITIATE
PROTOCOL STARTUP

USER PROGRAM ISSUES
CONTROL COMMANDS

ASSIGN TRANSMIT
AND
RECEIVE BUFFERS

USER PROGRAM ISSUES
BUFFER ADDflESS /
CHARACTER COUNT
COMMANDS

TRANSMIT

RECEIVE

THE DMV11 PERFORMS THE FOLLOWING
RECEIVE MESSAGE FUNCTIONS:
1. PROCESS RECEIVE HEADERS
2. CHECK CRC's
3. ACKNOWLEDGE (ACK) PROPERLY
RECEIVED MESSAGES
4. NEGATIVE ACKNOWLEDGE (NAK)
ERRONEOUSLY RECEIVED MESSAGES

THE DMV11 PERFORMS THE FOLLOWING
TRANSMIT MESSAGE FUNCTIONS:
1. CREATE DDCMP MESSAGE
HEADERS
2. GENERATE MESSAGE AND
HEADER CRCs
3. TRANSMIT MESSAGES

THE DMV11 PERFORMS THE FOLLOWING
MESSAGE TRAFFIC CONTROL FUNCTIONS:
1. MESSAGE SEQUENCING
2. ERROR RECORDING AND REPORTING
3. PROTOCOL SUPPORT
4. LINK MANAGEMENT

DMV11 ISSUES BUFFER
DISPOSITION RESPONSES,
CONTROL RESPONSES AND
INFORMA TlON RESPONSES

MK·2651

Figure 1-3

General Summary of DMV 11 Command/Response Structure

1-6

There are no file structure constraints on messages transmitted or received over DMV 11 networks;
however, the maximum data message length allowed is 16,383 bytes. Also, there are no restrictions as to
the type of data transmitted or received under DDCMP since all data is transmitted and received in
transparent form.
There are basically three types of DDCMP messages: the data message, the control message, and the
maintenance message (refer also to Appendix A for additional information on DDCMP).

1.7.1 Data Messages
DDCMP data messages consist of two parts: the message header and the message body. The header
consists of eight bytes of control information necessary for successful transmission of the message.
Included in these eight bytes is the block-check count (BCC) for the header, the byte count of the message
body, and the tributary address. The header also contains two control bits; one that indicates resynchronization after this message, and one that controls line turnaround. The message body consists of the
message and a BCC for the message. Both BCC characters are used by the DMVll to validate messages
as they are received.
The header is assembled by the DMV 11 and transmitted with the message body to form the data message.
The receiving DMV 11 uses the header to verify the address and ensure that the message is received in the
correct sequence. The header is also used to determine the number of bytes to transfer to the user
program. The header is discarded when the message is successfully passed to the user program.

1. 7.2 Control Messages
Control messages are used to manage message traffic. They are eight-byte DDCMP messages which are
passed between control and tributary stations under sole control of the DMV 11. Two examples of control
messages are acknowledge (ACK) and negative acknowledge (NAK). ACKs indicate successful reception
of messages while NAKs indicate unsuccessful reception. Control messages in multipoint also contain the
address field to identify the tributary to which the message is sent or received from.
1.7.3 Maintenance Messages
Under DDCMP, a DMV 11 has two data transfer modes: the DDCMP run state, and the DDCMP
maintenance state. In the run state, a DMVll receives and transmits data messages. In the maintenance
state, a DMVl1 receives and transmits only maintenance messages. A maintenance message is formatted
much like a data message. It is formed by an eight-byte header followed by a variable length message
body. The content of the body is determined by the user program. Maintenance messages may consist of:
1) operating or diagnostic programs transmitted by the control station for down-line loading into the CPU
of a specified tributary, or 2) a portion of the contents of a tributary's CPU memory as requested by the
control station. The request of this information is also handled by a maintenance message.
1.8 GENERAL SPECIFICATIONS
Environmental, electrical, and performance specifications for all DMV 11 configurations are listed In
Sections 1.8.1 through 1.8.3.
1.8.1 Environmental Specifications
The DMV11 is designed to operate in a class C environment as specified by DEC STD 102 (extended).
Operating Temperature
Relative Humidity

10% to 90% with a maximum wet bulb temperature of 28°C (82°F) and a minimum dew point
2°C (36°F).

1-7

1.8.2 Electrical Specifications
The DMV II requires the following voltages from the LSI-II bus for proper operation.
Option

Voltage

DMVII-M

+5 V @ 4.7 A
+12 V @ 0.380 A

DMVII-N

+5 V @ 4.4 A
+12 V @ 0.260 A

A -12 V @ 250 rnA required by the level conversion logic for both versions is generated off the + 12 V by
a switching inverter.

1.8.3 Performance Specifications
Performance paramete'rs are as follows:
Operating mode

Full- or half-duplex

Data format

Synchronous DDCMP

Data rates

Up to 56K bls

Tributaries supported

Up to 12

DMV11s may be connected to DMPl1s/DMVlls, DMRlls, DMClls, and any other synchronous
controller running DDCMP protocol.

1-8

CHAPTER 2
INSTALLATION

~.I
iNTRODUCTiON
This chapter provides all the information necessary for a successful installation and subsequent checkout
of the DMV 11. Included are instructions for unpacking and inspection, preinstallation, installation, and
verification of operation.

2.2 UNPACKING AND INSPECTION
The DMV 11 is packaged according to commercial packing practices. When unpacking, remove all
packing material and check the equipment against the packing list. Inspect all parts and carefully inspect
the module for cracks, loose components, and separations in the etched paths. Report damages or
shortages to the shipper and notify the DIGITAL representative.
2.3 INSTALLATION CONSIDERATIONS
Installation of the DMV 11 microcontroller /line unit subsystem should be done in three phases:
•

Phase I - Preinstallation considerations
Verify system requirements, system placement, and configuration requirements.
Network topology chart
For multipoint networks it is absolutely necessary to know the configuration of the DMV 11
(that is; control tributary, HDX, FOX, and so on) locations of tributaries (w/address), and
where in the network they are connected (control, Trib 187, Trib 98, Trib 208) or else
troubleshooting will be extremely difficult.

•

Phase II - Microcontroller /line unit installation
Configure, install, and verify the microcontroller /line unit module VIa the appropriate
diagnostics.

•

Phase III - DMV 11 system testing
Verify the DMVII microprocessor subsystem operation with the functional diagnostics and
system exerciser programs.

2.4 PREINSTALLATION CONSIDERATIONS
The following should be considered prior to ordering a DMV 11 communications interface to ensure that
the system can accept the DMVII and that it can be installed correctly. The steps should also be verified
at installation time.
It is strongly recommended that a topology diagram be drawn at installation time and maintained
throughout the life of the installation. Figure 2-1 shows a local network topology and Figure 2-2 shows a
remote network topology.

2-1

1
1

J TX

ELEVATOR SHAFT

... V

DELTA
11/70
DMP11
TRIB 3
RSTS XX.X
DE - XX.X

SUSPENDED CEILIN G
ROOM 515

I
RX

Jl
J

I TX
GAMA
11/23
DMV 11
TRIB 2
RSX 11M
OM - XX.X

BETA
11/34
DMP 11
TRIB 1
RSX11 M
OM - XX.X
ROOM 412

ROOM 430

......
.....

I
I

I TX

ALPHA
VAX 11/780
DMP 11
CONTROL
VMS XX.X
DV - XX.X
ROOM 111
MK-2S02

Figure 2-1

Local Network Topology

2-2

MERRIMACK
VAX. 11/780
VAX. VMS XXX
DV-XX.X
*NOTE 1
*NOTE 2
CONTROL
*NOTE 1
PATCH PANELS ARE
RECOMMENDED BUT MAY
NOT ALWAYS BE USED.lFTHEY
ARE USED, THEIR PHYSICAL
LOCATION SHOULD BE
INDICATED.

NASHUA

4800

~4~8~0~0-+~rl

NASHUA
EXCHANGE

11/60
RSTS XXX
DE-XXX
*NOTE 1
*NOTE 3

* NOTE 2
MODEM - 208A
CONTROL STATION OPTIONS
SEE TABLE 2-1

TRIB 1

*NOTE 3
MODEM - 208A
TRIBUTARY OPTIONS
SEE TABLE 2-2

TEWKSBURY

,....

....

.....--

LOWELL
EXCHANGE

I-- I-

VAX. 11/750
VAX VMS XXX
-- DV-XX.X
*NOTE 1
*NOTE 3
TRIB 2

4800

MAYNARD
EXCHANGE

4800

MARLBORO
4800
11/23
RSX-11 M
V.3.2
DM XXX
*NOTE1

MARLBORO
........- - - 1 EXCHANGE

MAYNARD

11/23
RSX-11 M
V.3.2
*NOTE 1
*NOTE 3
TRIB 3

*NOTE 3
TRIB 4

MKV86-1662

Figure 2-2

Remote Network Topology

2-3

Table 2-1

Typical Host Options of a Bell 208A™ Data Set (4800 b/s)
Full-Duplex Operation

Data Set Options

DEC Recommended Settings

Transmitter timing

Data set (internal)

Carrier control

Switched

Request-to-send operation in
continuous carrier mode

Switched

One second holdover at
receiver on l~ne dropouts

Not provided

New sync-option to squelch
receiver clock

Not used - NS is strapped OFF
within the data set

Data set ready lead option
for analog loopback testing
by data terminal

CC is ON when the AL button (only)
is depressed

Bell 208A ™ is a trademark of Western Electric.

Table 2-2

Typical Tributary Options of a Bell 208A™ Data Set (4800 b/s)
Full-Duplex Operation

Data Set Options

DEC Recommended Settings

Transmitter timing

Data set (internal)

Carrier control

Switched (48.5 ms CA-CB delay)

Request-to-send operation in
continuous carrier mode

Switched (8 ms ±.5 CA-CB delay; 0-35
ms depending on distance) NI A

One second holdover at
receiver on line dropouts

Not provided

New sync-option to squelch
receiver clock

Not used - NS is strapped OFF
within the data set

Data set ready lead option
for analog loopback testing
by data terminal

CC is ON when the AL button (only)
is depressed

2-4

The topology diagram should provide the following information.
Cable routing -

Show the actual physical location of the cable trough and
indicate any equipment which might cause interference
such as an X-ray room.

Machine type -

Indicate whether the CPU is a PDP-ll/23, PDP-II/70,
PDP-ll/34, VAX-II/780, and so forth. (The network
could consist of a mixture of DMPlls and DMVlls).

Type of station -

Indicate if the station is a control or tributary station.

Physical address -

DDCMP address can range from 1-255.

Location -

Indicate by room number or other appropriate means, the
actual physical location of the equipment.

Node name-

The name given to the tributary if applicable.

Operating system and
version -

The name of the software operating system such as RSX11M V3.2.

DECnet version -

DECnet software version such as DECnet-llM V3.0.

Transmit and receive -

Show transmit and receive lines. Depict end nodes and
show termination. If a patch panel is used, indicate the
line numbers between patch panels.

NOTE
The use of patch panels and numbering of the lines is
recommended.
2.4.1 Device Placement
The DMV 11 can be installed in any LSI-II bus-compatible backplane such as H9276. On systems that
contain many high-speed direct memory access (DMA) devices, there is a probability of adverse bus
latency. To help prevent against this occurrence, the DMVII should be placed physically close to the
processor. As a result, this gives the DMVII a high DMA priority.
2.4.2

System Requirements
•

LSI-II bus loading
The M8053·MA or M8064-MA present two ac loads and one dc load to the LSI-II bus.

•

Power requirements
Check the power supply before and after installing the microcontroller/line unit to ensure
against overloading. Power requirements are listed in Table 2-3.

•

Interrupt priority
The interrupt priority is preset to level four.

2-5

•

Device address assignment
The DMV 11 address resides in the floating address space of the LSI-II bus addresses. The
ranking assignment of the DMV 11 for bus address is 24. (See Appendix B to determine the
proper bus address.)
The selection of the device address is accomplished by switchpacks on the microcontroller /line
unit module. Refer to Figures 2-3 and 2-4.

•

Device vector address assignment
The DMVII vectors reside in the floating vector space of the LSI-II bus addresses. The
ranking assignment of the DMVII for vector assignments is 46. (See Appendix B.)
The selection of the vector address is accomplished by a switch pack on the microcontroller /line
unit module. Refer to Figures 2-3 and 2-4.

Table 2-3

DMVll Voltage Chart

Module

Voltage Rating

Maximum
Voltage

Minimum
Voltage

Backplane
Pin

M8053-MA

+5 V @ 4.7 A
+12 V @ 0.380 A

+5.25
+12.60

+5.0
+ 11.40

AA2
AD2

M8064-MA

+5 V @ 4.4 A
+12 V @ 0.260 A

+5.25
+12.60

+5.0
+ 11.40

AA2
AD2

2-6

E113

E101

1r
___1

_ J 2_____

M8053

~
~

MK-2698

Figure 2-3

M8053 Switch Locations

2-7

E119

E107

M8064

~
~

MK·2521

Figure 2-4

M8064 Switch Locations

2-8

2.5 INSTALLATION
LSI-II configuration rules must be followed when installing the DMVII in the LSI-II bus-compatible
backplane. When installing the DMVII-SF (BA200 series enclosure), refer to Sections 2.7 through 2.14.
Proceed with the installation as follows by performing the following on the slot that will contain the
DMVIl.
l.

Verify that the backplane voltages are within the tolerances specified in Table 2-3.

Turn system power OFF.

Configure the correct device address (as determined from Appendix B) using switchpack
settings from Table 2-4.

Configure the correct vector address (as determined from Appendix B) using switch pack
settings from Table 2-5.

Using the flowchart in Figure 2-5, verify that the switch selectable features of the DMVII are
configured for the station being installed. Figure 2-6 and Tables 2-6 and 4-5 show switch
selectable features.

Insert the appropriate module test connector (H3255 and/or H3254) into the correct microcontroller /line unit connectors. Be sure to insert the test connector with "SIDE 1" (etched on the
test connector) visible from the component side of the module. Refer to Figures 2-7 and 2-8.
Schematics and outline drawings of each test connector used with the DMV 11 are provided in
Figure 2-9.

Install the DMV 11 and perform resistance checks on the backplane voltage source to ground.
This ensures that no short circuits exist. Refer to Table 2-3 for backplane pin assignments.

Turn system power ON and repeat Step l.

Load and execute the DMVl1 static diagnostics. Five error-free passes of each part is the
minimum for successful operation.
(C)VDMA ** - DMVII static logic test part 1
(C)VDMB** - DMVII static logic test part 2
(C)VDMC** - DMVl1 static logic test part 3
(C)VDMD** - DMVII static logic test part 4
(C)VDME** - DMVII static logic test part 5

10.

Remove the module turnaround test connector and connect the appropriate cable (see Table 2-7
and Figures 2-10 and 2-11) to the proper Berg™ connector for the DMVII option selected.
Refer to Table 2-7 for detailed information on cable requirements and to Figures 2-12 through
2-16 for system cabling configurations.
NOTE
When installing panel cables 70-20861, 70-20862,
70-20863, or 70-20864, it is important that the
panel be properly mounted to the rear-mounting
bulkhead to ensure adequate grounding (see
Figure 2-17).

Berg™ is a trademark of Berg Electronics.

2-9

When connecting the 70-20863 connector panel, verify that the appropriate modem switches on
the panel are properly configured for the option selected (see Figure 2-18). Table 2-8 lists each
of these options and required switch configurations. When connecting the BC55H interface
panel, refer to Table 2-9 for options and required jumper configurations.
Integral modem options require that a 75 ohms terminator be connected to each receive line
(70-20862 panel) at each end of a full-duplex and half-duplex network. Refer to Figure 2-11 for
DMVl1 remote cabling and to Figure 2-12 for DMVII to DMVII local cabling.
11.

Insert the appropriate cable turnaround test connector in the end of the cable. Refer to Table
2-7 for the specific test connector. Load and execute the static diagnostics specified in Step 9
using the external maintenance mode selected to verify the module and cable. Upon obtaining a
minimum of five error-free passes, proceed to the DMVII system test procedures (Section 2,6).
Figure 2-9 illustrates the various test connectors used in the DMV 11.
Loopback testing on the integrated modem panel is performed by SWI. Depress SWI IN for
loop back to module testing. Return SW 1 to the OUT position when diagnostic testing is
completed.

Table 2-4

Device Address Selection

MSB
15

SWITCH
NUMBER

12 111

\10

I I I I I
9

MB053 E53 MB064 E 5B

•

LSB
3

M8053
E54
MB064
E59

DEVICE
ADDRESS

760020
760040
760060

760100
0
UJ

(j)

::::l

ON
ON

::::l

--760200
--760300

--760400

--ON

760500

--ON

760600

--ON

760700

--761000

--762000

--ON

763000

--ON

764000

NOTE1:

SWITCH ON RESPONDS TO LOGICAL ONE ON THE BUS

NOTE 2:

Sl (MB053-E54 AND MB064-E59) IN UNUSED.

NOTE 3:

DEVICE ADDRESS MUST HAVE BIT 3 =0 (ONLY ADDRESSES ENDING IN 00. 20. 40
OR 60 CAN BE USED).
Iv1K\'86- -: 05:;

2-10

Table 2-5
MSB
15

Vector Address Selection

8 \ 7\61 5 \ 4 \ 3
I

M8053 E54
M8064 E59

...

•
SWITCH
NUMBER

LSB
0

1/0

ON
ON
ON
ON
ON
ON
ON
ON

ON
ON
ON
ON
ON
ON

ON
ON
ON

ON
ON

VECTOR
ADDRESS
300
310
320
330
340
350
360
370
400

ON
ON

---

500

---

600
ON

-----

700

NOTE: SWITCH ON PRODUCES LOGICAL ONE ON BUS
MK·2!183

2-11

THE FOLLOWING PROCEDURES USE EITHER SWITCH PACK E1 01 ON THE M8053 MODULE,
OR SWITCH PACK E1 07 ON THE M8064 MODULE

(SWITCH OFF = 1
SWITCH ON = 0
DEFAULT IS 0)

SET SW3
ON

SET SW3
OFF

SET SWl
OFF

SET SW2
ON

SET SW1
ON

SET SW2
OFF

LINE SPEED
SET SW9
ON

MODEM
SET SW9
OFF

MKV86-1681

Figure 2 5

D~.1V 11

Installation FIO'.v (Sheet

2-12

SET SW10
ON

SET SW4
ON

SET SW10
OFF

SET SW4
OFF

SET SW5
ON

SET SW5
OFF

CONFIGURE SW6,
SW7 & SW8 AS
SHOWN IN
FIGURE 2-6

MKV86-1682

Figure 2-5

DMVll Installation Flow (Sheet 2 of 3)

2-13

THE FOLLOWING PROCEDURES USE EITHER SWITCH PACK El13 ON THE M8053 MODULE,
OR SWITCH PACK El19 ON TH E M8064 MODU LE.

NO (MULTIPOINT)

SET SWl
THROUGH SW8
TO TRIBUTARY
NUMBER.
OFF=l,ON=O

SET SWl OFF
SET SW2
THROUGH SW8
ON

MKV86·1683

Figure 2-5

DMV11 Installation Flow (Sheet 3 of 3)

2-14

MODE DEFINED BY SW6, 7,8, ENABLED OFF
UNIT NUMBER FOR BOOTING, UNIT 0

= ON, UNIT 1 = OFF

AUTO ANSWER, ENABLED ON

lirPOWER ON BOOT, ENABLED OFF

DDCMP ADDRESS REGISTER
TRIBUTARY/PASSWORD

,REMOTE LOAD DETECT, ENABLED OFF

II I I
r---------

~BBB8BBB BBB

7 8 9 10

OFF = ONE

INTERFACE SELECT

M8053

EIA RS-232-C/RS-423-A

OFF

M8053

UNUSED

M8064

[:=JCJ
E101
E107

MODULE

INTEGRAL MODEM

El13
E119

SW10

CCITT V.35

HIGH-SPEED SWITCH

M8053
M8064

M8064
OR
M8053

SW9
M8053

BAUD RATE < 19.2K b/s

BAUD RATE 19.2K b/s OR
GREATER

OFF

NOTE M8064 SW 9 ALWAYS OFF
SWITCH
MODE DEFINITION
HDX PT-TO-PT/DMC LINE COMPATIBLE
FOX PT-TO-PT/DMC LINE COMPATIBLE
H OX PT- TO- PT
FOX FT-TO-PT
HDX MULTIPOINT CONTROL STATION

FOX MULTIPOINT CONTROL STATION
HDX MULTIPOINT TRIBUTARY
FOX MULTIPOINT TRIBUTARY

ON
OFF

ON
ON
OFF
OFF
ON
ON
OFF
OFF

ON
ON
ON
ON
OFF
OFF
OFF
OFF

ON
OFF
ON
OFF
ON
OFF

MKV86·1664

Figure 2-6

DMV 11 Switch Selectable Features

2-15

Table 2-6

Switch
Number

DMVll EIOI (M8053)/EI07 (M8064) Switch Selectable Features

Switch
Name

Switch Position
when Function
is Enabled

MODE ENABLE

OFF

Indicates that the DMV 11 mode of operation is defined in switches 6, 7, and 8. If
disabled, mode of operation must be
software assigned.

UNIT NUMBER
FOR BOOTING

ON or OFF

Defines which DMV 11 is performing the
remote boot if two DMV 11 options are
installed on the same LSI-II bus. This
switch offers the selection of:

DMVll Function/Description
when Switch is Enabled

Unit Number Zero = "ON"
Unit Number One = "OFF"
3

AUTO ANSWER

OFF

Causes the DMV 1 I to assert DTR and
wait for modem ready (DSR). DSR is the
indication that the call has been established. This sequence allows the DMV 11
to automatically answer all incoming calls
to the LSI-II computer station. If a valid
DDCMP message is not received within
30 seconds after a connection is established, DTR is dropped (hang up the
telephone ).

POWER-ON
BOOT ENABLE

OFF

Allows the power-on boot feature at the
remote/tributary station. The node which
is to receive the boot requests the host
station to start the primary MOP boot
procedure. The BOOT request is sent out
when the first poll message after the
remote station's power-up sequence is
complete.

REMOTE LOAD
DETECT ENABLE

OFF

Allows the remote load detect boot feature at the remote/tributary station. The
host node starts the booting sequence by
starting the primary MOP boot
procedures.

6,7,8

MODE OF
OPERATION

ON or OFF
(as applicable)

These three switches define the DMV 11
module's mode of operation, at device
boot (initialization) time, if switch 1 is set
to the "OFF" position. Refer to Table 4-5
for a listing of the different switch positions and the operating modes they
define.

2-16

Table 2-6

DMVll EI0l (M8053)/EI07 (M8064) Switch Selectable Features (Cont)

Switch
Number

Switch
Name

Switch Position
when Function
is Enabled

HIGH SPEED

OFF

DMV 11 Function/Description
when Switch is Enabled
Selects the baud-rate that the DMV 11
operates at:
HIGH SPEED = "OFF" = I9.2K b/s
and greater
LOW SPEED = "ON" = <I9.2K b/s

NOTE
The integral modem (M8064) requires switch 9 to be
set to the enabled ("OFF") position.
10

INTERFACE
SELECT

ON or OFF

"ON" =

CCITT V.35 modem interface selected.

"OFF" =

EIA RS-232-C or RS-423-A
modem interfaces selected.

NOTE
Switch 10 is not used with the M8064 (integral
modem) DMVII-N option.

2-17

Table 2-7
Cabinet
Kit

Cabinet Kits

Description

CK-DMV ll-AA

Cabinet kit for EIA RS-232-C with 53.34 cm (21 inch) cable for PDP-II /23S
70-20863-00 panel, H325 test connector, and BC08S-1 K cable.

CK-DMV Il-AB

Cabinet kit for EIA RS-232-C with 30.48 cm (12 inch) cable for Micro-II
70-20863-00 panel, H325 test connector, and BC08S-01 cable.

CK-DMVII-AC

Cabinet kit for EIA RS-232-C with 76.20 cm (30 inch) cable for PDP-II /23+
70-20863-00 panel, H325 test connector, and BC08S-2F cable.

CK-DMVII-A2

Cabinet kit for (non-FCC compliant) EIA RS-232-C with 91.44 cm (36 inch)
cable for unshielded cabinets containing H349 mounting panel, BC55H-03 cable,
and H325 and H3251 test connectors.

CK-DMVII-BA

Cabinet kit for V.35 with 53.34 cm (21 inch) cable for PDP-II/23S 70-20861-1 K
panel, H3250 test connector, and BCl7E cable.

CK-DMVII-BB

Cabinet kit for V.35 with 30.48 cm (12 inch) cable for Micro-II 70-20861-01
panel, H3250 test connector, and BCI7E cable.

CK-DMVII-BC

Cabinet kit for V.35 with 76.20 cm (30 inch) cable for PDP-I 1/23+ 70-20861-2F
panel, H3250 test connector, and BCI7E cable.

CK-DMVII-B3

Cabinet kit for (non-FCC compliant) V.35 with 7.62 m (25 feet) cable for
unshielded cabinets containing H349 mounting panel, BC05Z-25 cable, and
H3250 test connector.

CK-DMVII-CA

Cabinet kit for integral modem with 53.34 cm (21 inch) cable for PDP-II /23S
70-20862-00 panel, H8568 and H8570 test connectors, and 70-18250-1 K cable.

CK-DMVII-CB

Cabinet kit for integral modem with 30.48 cm (12 inch) cable' for Micro-I I
70-20862-00 panel, H8568 and H8570 test connectors, and 70-18250-0 I cable.

CK-DMVII-CC

Cabinet kit for integral modem with 76.20 cm (30 inch) cable for PDP-II /23+
70-20862-00 panel, H8568 and H8570 test connectors and 70-1 8250-2F cable.

CK-DMVII-C3

Cabinet kit for (non-FCC compliant) integral modem with 91.44 cm (36 inch)
cable for unshielded cabinets containing H349 mounting panel, BC55F-03 cable,
and H3257 and H3258 terminators.

CK-DMVII-FA

Cabinet kit for RS-423-A/449 with 53.34 cm (21 inch) cable for PDP-II /23S
70-20864-00 panel, H3251 test connector and BC08S-1 K cable.

CK-DMVII-FB

Cabinet kit for RS-423-A/449 with 30.48 cm (12 inch) cable for Micro-II
70-20864-00 panel, H3251 test connector, and BC08S-0 I cable.

CK-DMVII-FC

Cabinet kit for RS-423-A/449 with 76.20 cm (30 inch) cable for PDP-II /23+
70-20864-00 panel, H3251 test connector, and BC08S-2F cable.

CK-DMVII-F3

Cabinet kit for (non-FCC compliant) EIA RS-423-A/449 with 91.44 cm (36
inch) cable for unshielded cabinets containing H349 mounting panel, BC55H-03
cable, and H325 and H3251 test connectors.

NOTE 1:
Refer to Appendix E for more cabinet kit information.
NOTE 2:
MicroVAX uses same cabinet kit as the Micro-II.

2-18

CONNECT CABLE 70-20861 FOR V.35 INTERFACE

H3254
TEST CONNECTOR

~
L:JJ
Jl

H3255

TEST CONNECTOR ~

CONNECT CABLE BC08S
FOR RS-232-C OR RS-423-A
INTERFACE.

M8053

MKV86-1665

Figure 2-7

Test Connector Insertion for the M8053

2-19

CONNECT 70-18250
FOR INTEGRAL MODEM

H3254
TEST CONNECTOR

~
L.:...JJ

M8064

MK·2699

Figure 2-8

Test Connector Insertion for the M8064

2-20

J1
NUll ClK +
REC ClK +
TX ClK +
NUll ClK REC ClKTX ClK TX DATA-

Cj:

fr
-£

R DATA +

K
...

OJ)
~

TXINT

RECINT
TXINT

RECINT

DATA MODE

+
+

Y..

CTS
TER ROY

+
+

T
-B......8

RTS
REC ROY

J<...K

fX DATA +
R DATA

SIDE 1

Jl-

H3254

N--N
-.

FF
....
-

M-M

VIEWA
H3254 MODULE TEST CONNECTOR (J1 ON M8053/M8064)
MK-2645

000

AUX ClK +
TX ClK DIFF +
RX ClK DIFF +
AUX ClK TX ClK DIFF RX ClK DIFFTX DATA 01 FF +
RX DATA DIFF +
TX DATA DIFF RX DATA DIFF RTS
CTS
CDET
VIEWB

000
-00II

DTR
DSR

H3250

..
.-

..-

..
..

y-...

....V

w
..
--!
X
::.:

--.f
--B

S
...

• "!!'

F
....

!;j

E
:.

MK-2123

Figure 2-9

DMV11 Test Connectors (Sheet 1 of 4)

2-21

ffi

SEND COMMON
REC COMMON

TER IN SER
INCOMING CALL
TER RDY +

DSR +
SEND DATA +

...Z

--....JF

REC DATA +

SEND DATA-

K..K

REC DATANULL CLK +
SEND TIMING +
REC TIMING +
NULL CLK-

..-

SEND TIMING-

REC TIMING -

RTS +
CTS +

REC RDY +
NEW SIGNAL
SIGNAL QUALITY
SEL SIGNAL RATE
SIGNAL RATE IND

* SEC SEND DATA
* SEC REC DATA
* SEC RTS
* SEC CTS

..
..

TEST MODE

.....

RTS CTS REC RDY DSR TER RDY -

R
.......

E-E
---.;

1,.T

S5
V
.T

+
+

+
SIDE 1

---..

R-R

--i

t.,L

..-P

+
+

THl

TH2

H3255

6
......

K
E
--.
.-

VIEW C

C-C

B-B

LOCAL LOOP

STAND BY IND

...S

H-H

..-

SEL STAND BY

--qp

M
A-A

--PP
H
U

H3255 MODULE TEST CONNECTOR (J2 ON M8053)

----

NOT REQUIRED FOR DMV11
MKV86-1666

Figure 2-9

DlviV i i

2-22

!•

SHIELD GROUND
SIGNAL RATE INDICATION

SEND DATA +
SEND TIMING +

i
..·

REQ DATA +

REQ TO SEND +

REQ TIMING +

CLEAR TO SEND +
LOCAL LOOP

··

DATA MODE +
TERMINAL READY +

RECEIVER READY +
-.

SIGNAL RATE SEL
TERMINAL TIMING +

DATA MODE-

•

12
1j)

24
is
...

--...
28

H3251

3i
32
A

SELECT STANDBY

SIGNAL QUALITY

STANDBY INDICATION

13
A

25
-:

RECEIVER READY-

TERMINAL TIMING-

•

TERMINAL READY-

NEW SIGNAL

ii.-

REQ TO SEND-

TERMINAL IN SERVICE

•
-21

REQ DATA-

CLEAR TO SEND-

-u>~

2..0

RECEIVE COMMON

REQ TIMING-

SIGNAL GROUND

SEND TIMING-

-§

:..0;

TEST MODE

SEND DATA-

i
6'x
'7

REMOTE LOOP
INCOMING CALL

SEND COMMON

34
;..

VIEW D

36
-

-:;.;

~
H3251 CABLE TEST CONNNECTOR

MK-2746

Figure 2-9

DMVll Test Connectors (Sheet 3 of 4)

2-23

H325
SCE --11.............
24......

SCT_:~_1_5......
SCR_..._~_1_7__

SECXMIT~
CUT TO TEST
NEW ,SYNC
SIDE l '
•

SECRCV~
XMITDATA~

RCVDATA~

~=:::=b
co::::=LJ

o ••••••••••••••••••• ••••••

NEW SYNC~____
14......
H326

DATASETRDy--.---6~
CUT TO TEST*
NEW SYNC

VIEW E

.....i--. .

DTR-....

RI_.-.......
22~
H326 CABLE TEST CONNECTOR
MK·2124

Figure 2-9

DMVll Test Connectors (Sheet 4 of 4)

2-24

VIEW A
40-PIN SOCKET

~ -+I

N
R
T

M
P
5

DO
FF

CC
EE
HH

J
L

JJ
LL

40-PIN SOCKET

I+-

A
C
E

H
K

~ ""ef"
DO
FF

f.--

P
5

U
W
y
AA
AA
EE

HH
KK

RR
TT

PP
55

~=E§~pY.~
TT
55
VV

B
0
F
J
L
N
R
T
V
X
Z
BB

BC08S (RS-232-C/V.35/RS-423-A. RS-449 INTERFACE) PANEL CABLE
TK-ll009

VIEW B

(""'
'1

[!.I

~ ,~ I
.;'

25 PIN
CONN.

25 PIN
CONN.
BC22F-l0 (RS-232-C INTERFACE) MODEM CABLE
TK-ll0l0

VIEWC

37 PIN
CONN.

37 PIN
CONN.
BC55D-33 (RS-423-A/449 INTERFACE)MODEM CABLE
TK-ll0ll

Figure 2-10

DMV11 Cable Drawings (Sheet 1 of 3)

2-25

34 PIN
CONN.

o
37 PIN
CONN.

BC17E (V.35 INTERFACE) MODEM CABLE

TK-11012

VIEW E

BC56D TWINAX CABLE (WITH FEMALE CONNECTOR)
NOTE:
BC56A CABLE IS SIMILAR TO BC56D AND BC56B CABLE IS
SIMILAR TO BC56E, EXCEPT BOTH USE TRIAX CONDUCTORS
RATHER THAN TWINAX. ALL USE H8568 AS AN ADAPTOR.

~l~:.r_..........;_~~€>
:~.

' " ' -........;;;;;I"I..Iw.... _ _ _

BC56E TWINAX CABLE (WITH MA"LE CONNECTOR)
TK-11013

VIEW F

BC55T TWINAX CABLE
NOTE:
BC55S CABLE IS SIMILAR TO BC55T CABLE, EXCEPT
USES TRIAX CONDUCTOR RATHER THAN TWINAX. BOTH ALSO
USE H8568 AS AN ADAPTOR.
TK-11014

Figure 2-10

DMV11 Cable Drawings (Sheet 2 of 3)

2-26

VIEW G
/70-20862

70-20862
CONNECTOR PANEL
(FRONT VIEW)
70-18250 (INTEGRAL MODEM)PANEL CABLE
NOTE:
TYPE OF DUPLEX OPERATION MUST ALWAYS BE ESTABLISHED
BY VIEWING CONNECTOR MATING FROM SIDE 2 (REAR
SIDE OF 70-20862 ASSY, OR SAME SIDE AS SWITCH S1).
HALF (BLUE) SIDE OF CONNECTOR FACING VIEWER PROVIDES HALF;
FULL (RED) SIDE OF CONNECTOR FACING VIEWER PROVIDES FULL.
MKV86-1667

VIEWH

1[(

ill

H8568

H8570

TEST CONNECTOR

TERMINATOR
TK-ll016

VIEW I

UU
70-20861 PANEL CABLE

L:.J
\\
VV

MKV86-1669

Figure 2-10

DMV 11 Cable Drawings (Sheet 3 of 3)

2-27

VIEWA
RS-423-A

RS-232-C

W1 r::=J
W2 r::=J
W3 r::=J
I
'\
I
I
1,_ --, I W4 r::=J
W5 r::=J
• • I 1 W6 c:::::J
:
1
I
I
• II W7 c::J
• • I I W8 c:::::J
W9c:::::J
J1

r----'

r--'-...
---,
··
,;

.1
(
•I
I
-I
I •I
I : :I
I· ·1
I : :I
I • •I
I • _1

c:::::JW15
c::::::J W16
c::::::J W17
c:::::J W18
c:::::J W19
c:::::J W20

I : •I

I '-_!.J I
~\
I
I
\

• : I1
• • II C5 c:=J
: I 1 C6c=J
• • I I C4 c::::=J
: I1
C3 c=J
• - I I C1 c:=J
• : 11
• II C2 c::=J
1 • • 1 1 W10c::::::J
I --~) 1 W11 r::=J
1
W12 r::=J
~\
I
I
""'---- "
W13c:::::J

>
>

W14c:::::J
BC55H (RS-232-C/RS-423-A) INTERFACE PANEL CABLE
MKV86-1678

* *

VIEW B

B O. A
000
F 00
J 0 0
L 0
NO 0
RO 0

•K
T. •

@
B

•••••
•

000·
.0.0

• • • ••
0·.

M
P
S
V. 0 U
XO 0 W
Z • 0 y
BB
AA
DO
CC
FF O. EE
JJ O. HH
LL O. KK
NN 00 MM
RR O • PP
n
SS
UU
W

••
••

000·
0000
0
0
0
0

C
E
H

<
<

STRAIN RELIEF

••
••
**

BC05Z-25 (V.35 INTERFACE) MODEM CABLE

INDICATES CAVITIES USED TO
MOUNT STRAIN RELIEF
MKV86-1679

Figure 2-11

DMV 11 Non-FCC Compliant Cable Drawings (Sheet 1 of 2)

2-28

VIEWC

FEMALE CONNECTORS
OUT

OUT

BC55F (INTEGRAL MODEM) PANEL CABLE

MALE CONNECTORS
CONNECTOR PANEL
(FRONT VIEW)

VIEW D

H3258

H3257

TERMINATOR
(FEMALE)

TERMINATOR
(MALE)
MKV86-1680

Figure 2-11

DMVII Non-FCC Compliant Cable Drawings (Sheet 2 of 2)

2-29

RS-232-C INTERFACE
BC22E OR BC22F CABLE
I

DMV11-RS-232

BC08S
CABLE

o
O

o
J2 TEST
CONNECTOR
H3255

TI S1
c::J S2
6-10
c=:J S3
11 -1 5
c::::J S4
16-20
0

D
0

H325 TEST
CONNECTOR

70-20863
PANEL

V.35 INTERFACE
BC17E CABLE

70-20861

BC08S
CABLE

DDS
MODEM

PANEL
CABLE

H3250TEST
CONNECTOR
M8053
J1 TEST
CONNECTOR
H3254

RS-423-A/449 INTERFACE
BC55D CABLE
BC08S
CABLE

DMV11-RS-423

MODEM

o
J2 TEST
CONNECTOR
H3255

H3251 TEST
CONNECTOR

70-20864
PANEL
MKV86-1668

Figure 2-12

2-30

RS-232-C/423-A

Jl
BC55H

MODEM

H3251 (BC55D)
H325 (BC05D)

NOTE:

BC55H CAN ONLY BE INSTALLED IN SYSTEMS BUILT IN 1982 OR LATER THAT
CONTAIN AN H349 MOUNTING PANEL. OLDER SYSTEMS NOT CONTAINING AN
H349 MOUNTING PANEL CAN USE BC55C IN PLACE OF BC55H.

V.35 INTERFACE
V.35
MODEM
BC05Z-25

~ --~IU

J2
M8053

Jl TEST
CONNECTOR
H3254

CABLE TEST
CONNECTOR
H3250

MKV86-1670

Figure 2-12

DMV11 Remote System Cabling Diagram (Sheet 2 of 2, Non-FCC Compliant)

2-31

FULL-DUPLEX

M8064
M8064

70-20862
PANEL

INSTALL 75f2
TERMINATOR
CONNECTOR
(H8570) IN J2

70-18250

HALF-DUPLEX

M8064
M8064

INSTALL 75f2
TERMINATOR
CONNECTOR (H8570)
IN J4

70-18250

NOTES:
TYPE OF DUPLEX OPERATION MUST ALWAYS BE ESTABLISHED
BY VIEWING CONNECTOR MATING FROM SIDE 2 (REAR
SIDE OF 70-20862 ASSY. OR SAME SIDE AS SWITCH S1).
HALF (BLUE) SIDE OF CONNECTOR FACING VIEWER PROVIDES HALF;
FULL (RED) SIDE OF CONNECTOR FACING VIEWER PROVIDES FULL.
MKV86-1671

Figure 2-13

DMVII to DMVII Integral (Local) Modem Cabling Diagram (Point-to-Point)
(Sheet 1 of 2, FCC Compliant)

2-32

FULL-DUPLEX
INSTALL 75Q
TERMINATOR
CONNECTOR (H3257)

HALF-DUPLEX

INSTALL 75Q
TERMINATOR
CONNECTOR (H3257)

BC55F

* FOR 56K b/s USE CABLE BC55N OR BC55D. BC55E. BC55T. AND (2)
H8568.
NOTE:

BC55F CAN ONLY BE INSTALLED IN SYSTEMS BUILT IN 1982
OR LATER THAT CONTAIN AN H349 MOUNTING PANEL. OLDER
SYSTEMS NOT CONTAINING AN H249 MOUNTING PANEL CAN
USE BC55A IN PLACE OF BC55F.
MKV86-1672

Figure 2-13

DMV11 to DMV11 Integral (Local) Modem Cabling Diagram (Point-to-Point)
(Sheet 2 of 2, Non-FCC Compliant)

2-33

HDX NETWORK
TERMiNATOR
(H8570)

M8064

CONTROL
STATION

-,
I
I

70-20862
PANEL

BC55T
, _
_ _ _ --1I
I

TRIBUTARY

-,
I

70-20862
PANEL

,---- J
BC55T

I
I
I

TRIBUTARY

70-20862
PANEL

BC55T

,------1
I

TRIBUTARY

70-20862
PANEL

I 0

TERMINATOR
(H8570)
MKV86-1673

Figure 2-14

Half-Duplex Multipoint Network (Control Station End Node)

2-34

FDX NETWORK

CONTROL
STATION

TRIBUTARY

TERMINATOR
(H8570)
NOTES:
SOLID LINE REPRESENTS CONTROL STATION TRANSMIT TO
TRIBUTARy'RECEIVE.
DASH LINE REPRESENTS CONTROL STATION RECEIVE FROM
TRIBUTARY TRANSMIT.
BOTH ENDS OF THE TRANSMIT LINE FROM THE TRIBUTARIES NEED TERMINATION
IN ADDITION TO THE ONE TRANSMIT LINE FROM THE CONTROL STATION,
MKV86-1674

Figure 2-15

Full-Duplex Multipoint Network (Control Station End Node)

2-35

TERMINATOR

IH85701
TRIBUTARY

70-20862
PANEL

BC55T

CONTROL
STATION

70-20862
PANEL

® r@I ),
,----+--~@ Y @J
J4

TX I °RX

TRIBUTARY

70-20862
PANEL

TRIBUTARY

70-20862
PANEL

TERMINATOR

IH85701
NOTES:
SOLID LINE REPRESENTS CONTROL STATION TRANSMIT TO
TRIBUTARY RECEIVE.
DASH LINE REPRESENTS CONTROL STATION RECEIVE FROM TRIBUTARY
TRANSMIT.
SINCE THE CONTROL STATION IS NOT AN END MODE THERE IS A NEED TO
TERMINATE TWO SETS OF TRANSMIT LINES FROM THE CONTROL STATION.
ADDITIONALLY BOTH ENDS OF THE TRANSMIT LINE FROM THE TRIBUTARIES.
MKV86-1675

Figure 2-16

Full-Duplex t-.1ultipoint Net\'/ork (Control Station Inner Node)

2-36

70-20861-XX

FCC
BULKHEAD
(REAR VIEW)

FCC
BULKHEAD
(FRONT VIEW)

70-20862-01

70-20861-XX

72-20863-01

70-20864-01

NOTE: ALL POSSIBLE CABINET KITS ARE SHOWN.
MKV86·1676

Figure 2-17

DMV11 Cabinet Installation to FCC Bulkhead

2-37

25 PIN
D SUBMINIATURE

J2
5
~--~--------------+-~

TERM IN SERVICE
SEl STNDBY
RTS

SEl SIG RATE

NUll ClK

L _____ J
RECV ClK

SEC RTS
lOCAL lOOP

XMIT ClK

REMOTE lOOP
XMIT DATA
RECV DATA
CTS
RING
DSR
CARRIER
DTR
SIG GND

m~AMEGND
~~RMAllY
OUT

MKV86-1677

Figure 2-18

DMV 11 to RS-232-C Interface Panel (70-20863)

2-38

Table 2-8

Switch Function Settings on 70-20863 Panel for RS-232-C Interface

I TM 142 25

MAKE BUSY

14 S11 ON

13 S14 ON

12 S18 ON ON

28 S20

ON ON

S15

ON ON

116 24

RS 105

SF 126

TT 113 24

RT 115 17

111

SCA SRS 120 19
LL
ON

141

ST 114 15
RL 140

NOTES:
1. ALL SWITCHES ARE OFF UNLESS SELECTED.
2. SWITCHES S3, S6, S7, S14, S15, AND S20 ARE CONNECTED TO A "DUMMY"
GENERATOR, WHICH PROVIDES AN OFF STATE CONDITION TO THE INTERFACE
3. SWITCHES S5, S9, S1 0, S12, S13, S16, S17, AND S19 SHOULD ALL BE OFF.
MKV86-0894

2-39

Be55H Jumper Modem Functions

Table 2-9

;;~

~
~

Y
MM
RR
RR
NN
LL
JJ
FF
V
N
R
K
P
UU
E
L
M
CC

~~3
0

Y'Q
23
21
11

~~
"X

5-J
~<o

Q:-

<l..~

..:)
')

W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
Wll
W12
W13
W14
W15
W16
W17
W18
W19
W20
W21

c§:>

rv
-.....;

'V'V
'" I? 0'
Q:-~<Q

rv
-.....;

0' Q
~a

IN
IN

~~~x~~ i;~

cy ~ry ry c)!?> Cy'V rv~
f:~ f: ~~............
... ...
Q:I?

.fj

CH
CG

23
16
14
12
21
4
15
17
18
19
1
25
24
25
24
13
25
1
2
3
5
6
7
8
20
22

NOTES

All JUMPERS ARE OUT UNLESS SELECTED.

JUMPERS W3, W4, W8, W12, W13 AND W18 ARE CONNECTED TO A "DUMMY" GENERATOR, WHICH PROVIDES AN
OFF STATE CONDITION TO THE INTERFACE.

JUMPERS Wl 0, W11 AND W16 ARE IN FOR TESTING WITH
THE H325.

C
F
J
T
Z

VV
BB
DO

CI
SBB
SBA
SCF

IN
IN
IN
IN
IN
IN

IN
IN
IN

IN IN IN
IN IN IN IN
IN IN IN IN
IN IN IN IN
IN IN IN
IN IN IN IN
NOT NORMALLY INSTALLED
IN IN IN IN

IN
IN
IN

IN
IN
IN
IN
IN

SR
SO
SF
SR
SRD
SSD
SRR
RL
RS
ST
RT
LL
SRS

111
110
126
112
119
118
122
140
105
114
115
141
121

SCA

142
TM
DA
113
TT
SB
117
SS
116
SCB
SCS
121
MAKE BUSY
AA
101
SO
BA
103
RD
104
BB
CB
CS
106
CC
OM
107
AB
SG
102
CF
RR
109
CD
TR
108
IC
125
CE

IN
IN

CA
DB
DO

I
I

0"X

IN
IN
IN
IN

:'1'

......

2
33
16
16

14
7
5
8
10
1
18
17
36
32
28
4
6
9
11
19
13
12
15

MKV86-1685

2-40

2.6 DMVII SYSTEM TESTING
The final step in the installation of a DMVII subsystem is to exercise the DMVII as: 1) a unit on the LSI11 bus; and 2) a link in a communications network.
2.6.1 Functional Diagnostic Testing
Ensure that the specific cable turnaround test connector for the selected DMV 11 option is still installed at
the end of the cable. Load and execute the DMV 11 functional diagnostics with the external mode selected.
Upon obtaining a minimum of five error-free end passes, proceed to Section 2.6.2.
2.6.2 DEC/XII System Exerciser
The DEC/X 11 system exerciser for the DMV 11 can be run in two different operating modes, internal and
external. The internal mode selects faster LSI-II bus activity. The external mode requires that the specific
modem test connector be installed at the end of the cable. This is the preferred mode of operation. There
are two DEC/XII modules for the DMVII; DMD* and DME*.
2.6.3 Final Cable Connections
The final step in the installation process is to return the DMV 11 to its normal cable connections, either to
the appropriate modem or to the distribution panel. The DMV 11 system cabling diagrams in Figures 2-12
through 2-16 have been included to help show overall cabling for the various DMVII-XX options.
References to specified locations of the various test connectors during diagnostic testing are also included.
After the cables are connected to the appropriate modem or distribution panel, it is suggested that the data
communications link test program (DCL T) be exercised.
2.6.4 DMVII Link Testing
The DMV 11 can be exercised over a communications link by the data communications link test (DCLT).
It is suggested that DCLT be configured to run first on a cable test connector and then on a modem with
the modem analog loopback test feature selected (if the modem includes this feature). Next, the overall
communications link should be exercised with the remote computer system that contains a DMV 11.
2.6.5 MDM Diagnostics
The perfomance of the DMVII can be verified by running the MDM (MicroVAX Diagnostic Monitor)
diagnostics. Refer to the following documents for instructions on running the MDM diagnostics.
AA-FM7AA-DN

Micro VAX Diagnostic Monitor User's Guide

AZ-GM3AA-NM

Micro VAX Maintenance Guide

2-41

2.7 DMVII-SF SYNCHRONOUS INTERFACE OPTION
The DMVII-SF is an option for the BA200 series enclosure ONLY The DMVII-SF synchronous interface
option connects the Q22-bus to a modem by using a synchronous serial line. The DMV II-SF option module
(hereafter referred to as DMV 11) is quad-height, with a BA200 style bulkhead handle (Figure 2-19).
The DMVII serial line conforms to EIA standards RS232-C, RS423-A, and Y.35.

DMV11
M8053

MKV88-1616

Figure 2-19

DMV II-SA Module (M8053-PA) with Bulkhead Handle

2-42

2.7.1 BA200
.
The
BA20
SerIes System
ac
Figure
has 1a !ncIosures
sows the 12- or l2-slot , Q
s ot BA2l3
-bus b k
The backplane .
and the 6-slot B plane and one
all 12 slots
the Q22 b
A214 enclosure chor two modular p
I through f lcroVAX syste
- us on the AB
aSSlS.
ower supplies
use the CO
of each slot. The
.
.
or their
BA200 serie
memory interconn of slots 1 throu h CD mterconnect i .
(three disk d .enclosures with m
ects.
g 3, and MicroPO;
in

2-2g ~nclosure

to the drive

~.mplements

high-spe~J row~ows
~:~~~tnd d~ ~e)to~ ge fa~\~

done tape
area can hold
an power cables.· lxed disk drives

;~Plemented

- inch)
systems
e rear of the enc1os·ure,cmprovidi
(5.25
deVlces
.use
four standard 13 3
ng easy access

BA213 ENCLOSURE

BA214 ENCLOSURE
MA-0875-87

Figure 2-20

BA220
. Enc10sure ChaSSlS
, Senes
.

2-43

2.7.2 Module Differences
The major difference between the BA200 series and other microsystem enclosures is the way in which you
connect external devices to the system. Option modules in the BA200 series enclosure connect directly to
external I/O connectors. Other enclosures require an insert panel and internal cabling between the option
module and the device.
There are two main differences between the modules used in the BA200 series enclosure and the modules
used in the other microsystem enclosures.
•

Option modules for external devices have bulkhead handles. These handles replace the insert
panels and internal cabling found in the BA23 and BA123 enclosures.

•

Standard Q22-bus modules (such as the RQDX3 and TQK50) have blank bulkhead covers.

The module handles and blank covers form an electrical seal that complies with FCC regulations for (1)
keeping radio frequency interference generated by the system in the enclosure, and (2) keeping radio
frequencies out of the enclosure. The module handles and blank covers also help to guarantee proper airflow.
See the Micro VA X Systems Maintenance Guide (EK-OOIAA-MG) for further information on the BA200
series enclosure.
2.8 INSTALLATION
This section provides a step-by-step procedure for unpacking, inspecting, and installing the DMV II-SF
option kit. Module and system configurations are also discussed.
CAUTION
ONLY qualified service personnel should remove or
install modules.
2.8.1

Unpacking the Option Kit

Look for external damage on the shipping container such as dents, holes, or crushed corners.

Do not dispose of the packing material until the module has been successfully installed and is
operational.

Put on your antistatic wrist strap.

Attach the wrist strap and antistatic mat to the BA200 series enclosure metal chassis. Use the antistatic
mat for placement of the module.

Use the checklist to identify the contents of the DMVII-SF option kit (Figure 2-21). The kit should
include the following:

One DMVII-S logic module (M8053)

One filler panel kit (70-24505-01). The filler panel kit should include two gap filler assemblies,
and four 1/4 inch flathead machine screws

One QMA DMVll Synchronous Controller User's Guide (EK-DMVQM-UG).

Remove the DMVII module from the antistatic bag.

2-44

Inspect the module for shipping damage.

Report any damage to the shipper and notify the DIGITAL representative.

DMV11
M8053

568

GAP FILLER ASSEMBLY (2)

~t=--=D===;

8~~-=u-=~
r i Y Y...

DMV11-SF
USER
GUIDE

-FLATHEAD SCREWS (4)

FILLER PANEL KIT
70-24505-01
MKV88-1611

Figure 2-21
2.8.2

DMV II-SF Option Kit Contents

Inspecting the FCC and EOS Clips
NOTE
To comply with FCC regulations, bulkhead handles
are equipped with transient protection FCC and EOS
clips. These clips provide ground through the module
handle.

Ensure that there is no residue or corrosion on the FCC and EOS clips on the module handle
(Figure 2-22). If so, remove it with alcohol. Also, ensure that there is no residue and corrosion on the
FCC and EOS clips on the gap filler assemblies.

Ensure that the FCC and EOS clips on the handle are in an arched shape. When depressed slightly,
they should return to their original shape.

If any clip is missing or broken, replace it with EOS clip (PN 12-26922-01) or FCC clip
(PN 12-26340-01).
2-45

MKV88-1613

Figure 2-22

FCC and EOS Clips

2.8.3 Software Backup
It is the customer's responsibility to perform a software backup. DIGITAL Field Service should make sure
that the customer has taken this step before it starts to configure the system.
2.8.4 Configuration
The following sections contain information on configuring the system and the DMV II-SF option.
2.8.5 Checking the System Configuration
Complete the BA200 series enclosure configuration worksheet to make sure that you do not exceed the
system's limits for power and bus loads (Figure 2-23).
You need to gain access to the modules installed in the system backplane before configuring the system.
Refer to the system's documentation for further information on how to gain access to the system modules.

2-46

12·SLOT ENCLOSURE
RIGHT -HALF POWER SUPPLY
SLOT
(ABCD)

CURRENT
5V

MODULE

AMPS
12 V

POWER
(WATTS)

BUS LOADS
AC
DC

1
2
3

4
5
6
MASS STORAGE

»> TAPE 1
»> DISK 1
TOTAL: RIGHT -HALF
POWER SUPPL Y
33.0

MUST NOT EXCEED

7.0

230.0

LEFT -HALF POWER SUPPLY
SLOT
(ABeD)

MODULE

CURRENT
5V

AMPS
12 V

POWER
(WATTS)

0.0

8
9

10
11

12
MASS STORAGE
DISK
DISK

0.0

DISK

0.0

35.0

20.0

TOTAL LEFT·HALF
POWER SUPPL Y
MUST NOT EXCEED

33.0

7.0

230.0

TOTAL BUS LOADS
MUST NOT EXCEED

6·SLOT ENCLOSURE
POWER SUPPLY
SLOT
(ABCD)

MODULE

CURRENT
5V

AMPS
12 V

POWER
(WATTS)

BUS LOADS
DC
AC

1
2
3
4

5
6
TorAL: POWER SUPPLY

MUST NOT EXCEED

330

7.0

230.0

35.0

20.0

TOTAL: BUS LOADS
MUST NOT EXCEED

* NOTE: POWER SUPPLIES MAY DIFFER. CHECK YOUR
POWER SUPPLY SPECIFICATIONS TO CONFIRM
THE MAXIMUM WATTAGE.

Figure 2-23

BA200 Series Configuration Worksheet

2-47

To check the system configuration, perform the following steps.
1.

On the configuration worksheet, list all the devices already installed in the system.

....

L..

List all the devices you plan to install in the system .

Fill in the information for each device, using the device information listed in Table 2-10.

Add the columns. Make sure the totals are within the limits for the enclosure.
Table 2-10 Power and Bus Load Data
Factory-Installed
Option

Current (Amps)
(Max)
+5 V
+12 V

CXA16-M
CXB16-M
CXY08-M
DEQNA-SA
DMV11-M
DPV11-SA
DRQ3B-SA
DRV1 W-SA
DZQ11-SA
IBQ01-SA
IEQ11-SA
KA620-AA
KA630-AA
KDJ11-BF
KDJ 11-SA/SB
MRV11-D
MS630-BB
MS630-CA
MSV11-JD
MSV11-JE
MSV11-QA
RDQX3-M
TQK50
M9060-YA
RD53A-EA
RD54A-EA
TK50E-EA

1.6
2.0
1.8
3.5
4.7
1.2
4.5
1.8
1.0
5.0
3.5
6.2
6.2
5.5
3.47
1.6*
1.8
3.1
3.74
4.1
2.4
2.48
2.9
5.3
0.9
1.3
1.35

200 rnA
0.0
300 rnA
0.50
0.38
0.30
0.0
0.0
0.36
0.0
0.0
0.14
0.14
0.2
0.19
0.0
0.0
0.0
0.0
0.0
0.0
0.06
0.0
0.0
2.5
1.34
2.4

* Value is for the unpopulated module only.

2-48

Power
(Max)
Watts

Bus Loads
AC
DC

10.4
10.0
12.6
23.5
28.1
9.6
22.5
9.0
9.3
25.0
17.5
32.7
32.7
29.9
19.6
8.0*
9.0
15.5
18.7
20.5
12.0
13.1
14.5
26.5
34.5
22.6
35.6

3.0
3.0
3.2
2.2
2.0
1.0
2.0
2.0
1.4
4.6
2.0
2.7
2.7
2.6
3.0
3.0
0.0
0.0
2.7
2.7
2.0
1.9
2.8
0.0
0.0
0.0
0.0

0.5
0.5
0.5
0.5
1.0
1.0
1.0
1.0
0.5
1.0
1.0
1.0
1.0
1.0
1.0
0.5
0.0
0.0
0.5
0.5
1.0
0.5
0.5
0.0
0.0
0.0
0.0

2.8.6 Guidelines for Module Placement
The following sections provide guidelines for placing the module
in the backplane.
2.8.6.1 Bus Continuity
Bus grant signals pass through each installed module through the A connectors of each slot. Figure 2-24
shows the bus grant routing. Use a bus grant continuity card (M9074) in vacant backplane slots to ensure
bus continuity.
12

~----t----

------r---- ------r---- ------ ----

a:::

oCJ)
CJ)

~--~-----+-----+-----+----~----~----~----+-----+-----~--~~~--

a:::

MA-0617-87

Figure 2-24

Bus Grant Continuity Path

2.8.6.2 Power Supplies
The BA200 series enclosure contains one or two separate 230-watt power supplies.
•

In the 12-slot BA213 enclosure (with two power supplies installed), the right-side power supply
powers slots 1 through 6 and the left-side power supply powers slots 7 through 12.

•

In the 6-slot BA214 enclosure, the power supply is located to the left of the backplane and powers
all 6 slots.

Each power supply in the enclosure must have a minimum 5-ampere load on the 5-volt output to maintain
regulation. If a power supply does not meet the minimum load requirement, you MUST install a load
module (M9060-YA) in an open backplane slot powered by that power supply. The power supply enters an
error mode and shuts down the system if the minimum load requirement is not met.
Refer to Section 2.11, "Relocating Existing Modules," for procedures on installing or removing modules.

2-49

2.8.6.3 DMVII-SA Bus Priority
Table 2-11 shows the recommended module sequence.
Table 2-11 Recommended Module Order
MicroVAX

MicroPDP-ll/53

MicroPDP-ll/83

KA630/KA620

KDJ II-SAl -SB
MSVII-QA
MRVll
DEQNA
DPVll
DMVll
CXA16
CXB16
CXY08
IEQl1 *

MSVII-JD/-JE
KDJII-BF
MRVll
DEQNA
DPVll
DMVll
CXA16
CXB16
CXY08
IEQll *

DZQll
DRQ3B
DRVIW
TQK50**
RQDX3**

DZQll
DRQ3B
DRVIW
TQK50**
RQDX3

MS630-B/-C
MRVll
DEQNA
DPVll
DMVll
CXA16
CXB16
CXY08
IEQll *
IBQOl *
DZQl1
DRQ3B
DRVIW
TQK50**
RQDX3**
*
**

No restrictions on position.
Not applicable in BA214 enclosure.

2.8.7 Finding CSR Addresses and Interrupt Vectors
Sections 2.8.7. 1 through 2.8.8 con tain information on finding CSR addresses and in terru pt vectors.
2.8.7.1 MicroPDP-ll Systems
For information on how to find CSR addresses and interrupt vectors for modules in a MicroPDP-ll system,
refer to the MicroPDP-}} Systems Maintenance Guide (EK-MICll-SG).
2.8.7.2 MicroVA X Systems
To find CSR addresses and interrupt vectors manually for modules in a MicroVAX system, see the
Micro VA X Systems Maintenance Guide (EK-OOIAA-MG).
You may also use the CONFIG program in the MicroVMS or the VMS SYSGEN utility to determine the
correct CSR address and interrupt vector for the modules in the system. When you type a list of the devices
in the system, CONFIG automatically provides CSR address and interrupt vector information. Table 2-12
lists the devices supported by this utility.

2-50

Table 2-12 Devices Supported by SYSGEN

Device
DMVII
CXA16
CXY08
DEQNA
DPYll
DRVIW
DZQll
IEQll
RQDX3
TQK50

Enter at DEVICE>
Prompt
DMVII
DHVII
DHVII
QNA
nD\Tll

.iJ.L

.L .L

DRIIW
DZII
IEQll
UDA
TU81

To use the SYSGEN utility, type the following at the system command prompt:

MCRSYSGEN
Press <RETURN>. The utility responds with the prompt:

SYSGEN>
At the prompt, type:

CONFIGURE
Press <RETURN>. The utility responds with the prompt:

DEVICE>
At this point, enter the abbreviation for each device already installed in the system and for each device that
you intend to install in the system. Table 2-12 lists the abbreviations.
Enter one abbreviation per line, then press <RETURN>. The DEVICE> prompt prompts you for another
entry. If you are installing more than one unit of a particular device, enter a comma and the number of
devices after the abbreviation. For example, DHV 11,2 indicates two DHV 11 modules.
After you have entered all devices, enter <CTRL Z>. The program displays the following information for
each device entered:
•
•
•

CSR address and vector
Name assigned to the device by the operating system
Operating system support status (yes or no).

The program uses an asterisk (*) to indicate a floating address or vector. If there is more than one unit of a
particular device, the first address refers to the first device to be installed. To exit from the SYSGEN
utility, type <EXIT> at the SYSGEN prompt and press <RETURN>.

2-51

2.8.8 Configuring the DMV II-SF Option
Before installing the DMVII module, you must define two parameters by selecting them with the module's
switches E53 and E54. (Figure 2-25). The parameters are listed below.
..
•

Module address (CSR)
Interrupt vector address

Select the CSR address and interrupt vector for the DMVII by using switches on the module. The module
uses a floating CSR address and interrupt vector.

M8053

~
~

MKV88-1612

Figure 2-25

M8053-PA Module Layout

The DMV 11 CSR address resides in the floating address space and the interrupt vector resides in the
floating vector space of the LSI bus addresses. The ranking assignment of the DMVII for bus address is 24
and for vector address is 46. (See Appendix B to determine the correct bus and vector address.) Configure
the correct device address using switchpack settings from Tables 2-4 and 2-5.
NOTE
The actual DMVll settings depend on the other
modules installed in the system.

2-52

2.9 OPERATING SYSTEM SOFfWARE SHUTDOWN
It is the customer's responsibility to shut down the operating system software.
DIGITAL Field Service personnel should make sure that the customer has taken this step before testing the
system (Section 2.10).
2.10 TESTING THE SYSTEM
Test the existing system to make sure it is running correctly.
1.

Insert the diagnostic tape cartridge into the tape drive.

Run the MicroY.A.X diagnostic monitor (MDM) for MicroVAX systems, or run the XXDP+
diagnostic for MicroPDP-II systems. See Section 2.6 (DMVII System Testing) for further
information on testing and troubleshooting.

CAUTION
ALWAYS remove the tape cartridge from the tape
drive before turning the power switch off.
After successful completion of the test, remove the tape cartridge, turn the power switch off, and unplug the
.
ac power cord from the wall outlet.
2.11

RELOCATING EXISTING MODULES
CAUTION
Only qualified service personnel should remove or
install modules.

Check the recommended module order listed in Section 2.8.6.3. You may need to relocate eXIstmg
modules before installing the DMVII option. If you do not need to relocate existing modules, proceed
to Section 2.11.1.
2.11.1 Modules with Handles
Use the following procedure to remove modules with handles.
CAUTION
Wear a grounded antistatic wrist strap before removing or installing modules.
1.

Note the orientation of external cables connected to the module. Carefully label and disconnect
the cables.

Release the two 1/4-turn captive screws that hold the module's handle to the card cage
(Figure 2-26).

Unlock the release levers by simultaneously pulling up on the top lever and pulling down on the
bottom lever (Figure 2-27).

Pull out on the module's handle and remove it from the card cage.

2-53

Confirm the module CSR address and interrupt vector; change jumpers and switch settings,
if necessary.

Reverse this procedure to install modules with handles. Do not fasten the 1/4-turn screws until
you ins tali the DMVII moduie.

TO RELEASE: PUSH IN, TURN
COUNTER CLOCKWISE 1/4'- TURN.
TO FASTEN: PUSH IN, TURN
CLOCKWISE 1/4 - TURN.
Q

MA-0580-87

Figure 2-26

Releasing the Captive Screws

2-54

NOTE:

ATION SHO WS HOWLL
TO

~ ~ IC~~~ URS:LREAS~~!~~ ~~ ~~~

D LES
MA-0588-87

MODULES WITH A

•

Figure 2-27

h Release Levers

Unlockmg t e

2-55

2.11.2 Modules with Blank Covers
Use the following procedure to remove modules with blank covers.
CAUTION
Wear a grounded antistatic wrist strap before removing or installing modules.
1.

Release the two 1/4-turn captive screws that hold the blank cover to the card cage (Figure 2-28).

Pull the blank cover away from the card cage.

Note the orientation of any internal cables connected to the module. Some connectors are not
keyed. Carefully label and disconnect the internal cables.

Unlock the module release lever by simultaneously pulling up on the top lever and pulling down on
the bottom lever. For modules with plastic handles, pull the plastic handle and remove the module
from the card cage.

Confirm the module's CSR address and interrupt vector; change jumpers and switch settings,
if necessary.

Reverse this procedure to install modules with blank covers. Do not fasten the 1/4-turn screws
until you install the DMVII module.

2.12 VERIFYING THE GROUND CONNECTIONS
When installing a module with a blank bulkhead cover next to a module with a recessed handle, you MUST
install a gap filler assembly between the modules to meet FCC regulations. Without the gap filler assembly,
circuitry on the module is exposed. Two gap filler assemblies (PN 70-24071-01) are provided as part of the
filler panel kit.
Before installing the DMV 11 option module, verify the ground connections as follows.
1.

Check if any recessed-handle module has a module with a blank bulkhead cover or a flush handle
in the slot immediately before or after it.

If so, verify that a gap filler assembly is installed on the side of the blank bulkhead cover or the
flush handle that is next to the recessed-handle module (Figure 2-29).
NOTE
There SHOULD NOT be any open spaces between
the modules.

2-56

TO RELEASE: PUSH IN, TURN
COUNTERCLOCKWISE 1/4 - TURN.
TO FASTEN: PUSH IN, TURN

NOTE:
THIS ILLUSTRATION SHOWS HOW TO RELEASE
CAPTIVE SCREWS ON ALL BLANK COVERS AND
BULKHEAD HANDLES.
MA·0616-87

Figure 2-28

Removing the Blank Cover

2-57

SCREWS

BLANK COVER
NOTE:
THE GAP FILLER IS MOUNTED
ONTO THE BLANK COVER TO
CLOSE THE OPEN SPACE BETWEEN
THE RECESSED MODULE AND THE
BLANK COVER.

\11 A-061 0-87

Figure 2-29

Ground Connections

2-58

Install the gap filler assembly (if needed) as follows.
a.

Using the two screws and a gap filler assembly supplied with the filler panel kit (PN 7024505-01), -attach the gap filler assembly to the top and bottom of the side of the blank
bulkhead cover or the flush handle that fits next to the recessed-handle module. Make sure
the gap filler assembly fits into the tab indentations on the blank bulkhead cover or the flush
handle (Figure 2-30).

1/4 INCH
SCREW

GAP FILLER ASSEMBLY
MOUNTED ON BLANK
BULKHEAD COVER
MA-0589-87

Figure 2-30

Attaching the Gap Filler Assembly

NOTE
The gap filler assemblies that are included with the
filler panel kit are provided as spares if not used with
this installation.

Place the blank bulkhead cover with the gap filler assembly onto the card cage.
2-59

Insert the flush-handle module with the gap filler assembly attached into the card slot.

Ensure that there is correct ground, with no open spaces between the two modules.

Do not fasten the 1/4-turn captive screws until you have installed the DtvfV 11 module.

INSTALLING THE DMVll MODULE

2.13

CAUTION
BE CAREFUL not to snag the module's components
on the card guides or adjacent modules.
1.

Insert the DMV11 module into the appropriate card slot (Figure 2-31). The module will not be
locked in place.

Holding both the top and bottom release levers, lock the module in place by simultaneously
pushing down on the top lever and pulling up on the bottom lever.

Make sure that bus grant continuity is maintained from the CPU to the last module in the
backplane. Insert bus grant cards where needed.

Fasten the two 1/4-turn screws on the DMV11 and also on the other modules and bulkhead
covers in the system.

2.14

CONNECTING EXTERNAL DEVICES
NOTE
BE SURE to remove the tape cartridge from the tape
drive before turning the (1/0) power switch off (0).

After the testing has successfully completed, connect any external cables to the appropriate modules. See
Table 2-13 for cable information.
1.

Turn the (1/0) power switch off (0) and unplug the ac power cord from the wall outlet.

Feed one of the appropriate cable ends (Table 2-13 and Figure 2-32) under the system and plug it
into the connector on the bulkhead handle. Tighten the screws on the connector (Figure 2-33).
NOTE
The DMVII-SF option cable is not included in the
option kit and must be ordered separately.

Attach a modem to the other end of the extension cable. See modem documentation for the
location of the connector, and for instructions on using the modem.

The installation procedure is now complete.
NOTE
It is the customer's responsibility to bring up the
operating system software once installation is
complete.

2-60

HOW
TOMODULE
LOCK S
SH~~~RT
ALL

NOTE:
THIS I LLUSTRATION
VERS AND
RELEASE
WITHATT

~~HED

HANDLES.

231
Figure -

.
h Module
Insertmgt e

2-61

MA-0590-87

Table 2-13 Extension Cables
Interface

Adapter Cable

Extension Cable

Y.24jRS-232

BS19D-02

BC22F-10 10 [t (3.05 m)
BC22F-25 25 [t (7.62 m)
BC22F-35 35 ft (10.7 m)
BC22F-50 50 [t (15.2 m)

Y.35

BC19F-02

BC19L-25 25 [t (7.62 m)
BC 19L-50 50 ft (15.2 m)
BC19L-75 75 ft (22.9 m)
BC19L-AO 100 ft (30.5 m)

RS-423

BC19E-02

BC55D-10 10 [t (3.05 m)
BC55D-25 25 [t (7.62 m)
BC55D-35 35 [t (10.7 m)
BC55D-50 50 [t (15.2 m)
BC55D-75 75 ft (22.9 m)
BC55D-AO 100 [t (30.5 m)

15 WAY
25,35,37

50 WAY

DCE

Dt=:::=~<

DMV11 -SA OR SF
ADAPTER
CABLE

====:=:::10

l=(

EXTENSION
CABLE

~~----------------~~-------------------I
CUSTOMER PROVIDED
(EXISTING)
MKV88-1608

Figure 2-32

Cable Option Attachment

2-62

MKV88·1609

Figure 2-33

DMVll-SF Cable Connections

2-63

CHAPTER 3
COMMAND AND RESPONSE STRUCTURES
3.1 INTRODUCTION
This chapter defines DMVII command and response formats in all necessary detail, and describes all
programming sequences relevant to DMVII operation in the network environment. The CSR command
structure and. format of input commands and output responses, as well as data port descriptions, are
described in detail. Discussions include special programming techniques, user access to maintenance
mode, and user interpretation of status/error reporting.
3.2 COMMAND STRUCTURE
The DMVII command set is structured into two categories; input commands and output responses.
Brief overviews of input commands and output responses, including command codes and the handshaking requirements, are provided in this section.
Transfer of control and status information between the main CPU resident user program and the
DMVII is accomplished through four 16-bit control and status registers (CSRs). Input commands are
issued to the DMVII by the user program, and output responses are issued to the user program by the
DMVll.
NOTE
Normally only four CSRs are used, but in the 22-bit
address mode, eight CSRs are available.
3.2.1 Control and Status Registers
Four 16-bit CSRs are used to transfer control and status information. These registers are both byte and
word addressable. The eight bytes are assigned addresses in the floating address space in the I/O page
as follows:
16XXXO, 16XXX 1, 16XXX2, 16XXX3, 16XXX4, 16XXX5, 16XXX6, and 16XXX7.
For discussion, these byte addresses are designated byte select 0 through 7 (BSELO through BSEL 7).
BSELIO and BSELII are only used in 22-bit address mode. BSEL12 through BSELI7 are not used by
the user/DMVl1-command structure and are not referred to in this document.
The four word addresses are the even numbered locations and are designated select 0, 2, 4, and 6
(SELO, SEL2, SEL4, and SEL6). The CSR addresses are assigned to the floating address space. The
floating address ranking for the DMVII is 24 (See Appendix B). The relationship between the symbolic byte and word addresses for DMV II CSRs, and the actual CSR layout, is shown in Figure 3-l.
Figure 3-2 illustrates the fields in CSR bytes BSELO, BSEL2, and BSEL3 that comprise the fixed
format portion of both user-program commands and DMVII responses. This fixed format portion serves to identify the command/response type, address of the tributary that the command/response applies
to, and coordinate ownership of the CSRs between the DMVII and the user program. Detailed bit
descriptions of SELO and BSEL2 are provided in Tables 3-1 and 3-2 respectively.
The four bytes comprising SEL4 and SEL6 contain the fields pertinent to each user-program command
and DMVII response. Detailed descriptions of the SEL4 and SEL6 fields are presented in Sections 3.3
through 3.4.

3-1

e7
BSEL1

BSELO

SELO

BSEL3

BSEL2

SEL2

BSEL5

BSEL4

SEL4

BSEL7

BSEL6

SEL6

l __ B~L~ _ .L _ ~S~O_ _ J SEL10*
*SEL1 0 IS ONLY USED IN 22 BIT ADDRESS MODE
MK·2860

Figure 3-1

DMV11 CSRs Byte and Word
Symbolic Addresses
7

BSEL3

2
I

RQI

RDI

RDO

lEI

BSELO

COMMAND TYPE
CODE

BSEL2
SEL2

COMMAND/RESPONSE
FIELDS

BSEL5
1

BSEL7
I

lEO

TRIBUTARY ADDRESS

2
I

BSEL4
SEL4
I

COMMAND/RES'PONSE
FIELDS
I
I

*22-BIT
MODE

BSEL6
SEL6

o
MK·1636

Figure 3-2

Fixed and Variable Formats for Commands and Responses

Table 3-1

SELO Bit Functions

Name

Description

Interrupt
Enable In (lEI)

When set, this bit enables the OMV 11, upon asserting RDI (bit 4
of BSEL2), to generate an interrupt to vector address XXO.

1-3

Reserved

Interrupt
Enable Out
(lEO)

5-6

Reserved

Bits.
BSELO

When set, this bit enables the OMV 11, upon asserting ROO (bit
7 ~f BSEL2), to generate an interrupt to vector address XX4.

3-2

Table 3-1

SELO Bit Functions (Cont)

Bits

Name

Description

Request In
(RQI)

This bit is set by the user program to request access to the data
port. It is cleared by the user program when the data port is not
required for further issuing of commands. The user program may
leave RQI set if successive requests for the data port are pending.

Maintenance
Request

When set, along with master clear (bit ! 4 of SEL4), this bit
causes the DMV II to enter the maintenance register emulation
section of the microcode.

BSELI
8

NOTE
Detailed discussion of maintenance register emulation is presented in Section 4.8.
9-10

Reserved

Diagnostic
Mode

Reserved

Invoke P/MOP
Boot

When set, this bit allows diagnostic programs to change the mode
of operation of the DlVlV I I using the mode definition command to
override the mode switches. Additionally, when set during a mode
definition command, this bit causes the DMV I I not to set data
terminal ready (DTR).
Invoke primary MOP mode. When set to one, this bit causes the
DMVII at this multipoint station to request that the control station initiate the primary MOP (maintenance operation protocol)
boot procedure. In point-to-point networks, a DMV II having this
bit set requests the other station to initiate the primary MOP
boot procedure.

NOTE
The master clear bit (bit 14) must also be asserted
to use invoke P /MOP.
14

Master Clear

When set, this bit initializes the DMVII. The clock is enabled
and the RUN flip-flop is set. Master clear is self-clearing.

Run

This bit controls running of the microprocessor. I t is set by bus
initialization or master clear. When run is cleared the microprocessor halts.

3-3

Table 3-2 BSEL2 Bit Functions
Description

Bits

Name

0-2

Control/Response

These bits define the type of input command or output response as fol-

Code

lows.

Bits
2

Description
0

o0 0

Buffer address/character count
(RCV) command or buffer disposition (RCV complete) response

o0 1

Control command or control response

o 1 0

Mode definition command or
information response

o 1 1

Buffer disposition (RCV unused)
response

1 0 0

Buffer address/character count
(XMIT) command or buffer disposition (XMIT complete) response

Reserved

o
1 1 1

Buffer disposition (sent but not
acknowledged) response
Buffer disposition (not sent)
response

22-Bit Mode

This bit when set indicates to the DMV 11 that the buffer address is in
the 22-bit format.

Ready In
(RDI)

RDI is the DMVII response to RQI, indicating to the user program
that it has control of the CSRs to issue a command. I t is cleared by the
user program when the data port contains the input command. Clearing
RDI returns control back to the DMV 11.

5-6

Reserved

Ready Out
(ROO)

ROO is asserted by the DMVII to indicate that the data ports (SEL4
and SEL6) contain an output response for the user program. The user
program must clear ROO after it has read this information. Clearing
ROO returns the CSRs to the DMV 11.

3-4

3.2.2 Input Commands Overview
In general, input commands provide the means for the user program to assign, receive, or transmit buf":
fers to the DMVIl. Detailed field descriptions and formats of each input command are provided in
Section 3.3
There are four types of input commands that can be issued to the DMVII for execution.
•
•
•
•

Microprocessor control/maintenance command;
Mode definition;
Control;
Buffer address/character count.

With the exception of the microprocessor control/maintenance command, input commands require an
identification code in the first three bits of BSEL2 (see Figure 3-2). These codes, which define each
command and variations of specific commands within the command set, are defined in Table 3-2 and
listed in Table 3-3.

NOTE
CSR addresses are expressed in octal.
Table 3-3

Input Command Codes
Binary Code(BSEL2)

Input Command Type

Bit

Mode definition

Control

Buffer address/character count
(receive)

Buffer address/character count
(transmit)

3.2.3 Output Responses Overview
Output responses provide a means for the DMVII to report various normal and abnormal (error) conditions concerning the data transfer operation. Three basic responses are provided:
•
•
•

Buffer disposition;
Control;
Information.

The buffer disposition response is used to return both used and unused buffers to the user program.
The control response is used to report error conditions concerning the microcontroller /line unit hardware, data link, physical link, or remote station. It also passes protocol information to the user.
The information response provides information requested by a control command from the user program.

3-5

3.3

DMVll INPUT COMMANDS

This section provides detailed descriptions of each input command. Command formats and data port
usages are illustrated and defined. User-program execution requirements, command variables, and action taken by the DMVII in response to commands are discussed.

3.3.1 Microprocessor Control/Maintenance Command
This single byte command has two functions; to initialize and cause the DMVII to start running, and to
cause entry into the microcode maintenance loop when the maintenance request bit is set. At start-up
time under normal operating conditions, this is the first command issued by the user program in order
to initialize the DMV 11.
The format for the DMV 11 initialization register (BSEL 1) is shown in Figure 3-3. To set the master
clear bit and thereby cause entry into the DMVII running mode, the user program moves a byte with
an octal value of 100 to BSELl. As a result, all condition-sensitive logic in the DMVII is reset for startup, and the start-up diagnostic is executed. When the diagnostic completes satisfactorily, the run bit in
BS ELI is set to one. This indica tes that the D MV 11 is running and the microcode is executing.
Figure 3-4 presents a flow chart describing how to initialize the DMVII. A timeout counter is set to
avoid the possibility of the user program being caught in an endless loop in case the internal diagnostic
does not complete successfully.
765

MK-2513

Figure 3-3

Microprocessor Control/Maintenance
Command Format

3.3.2

Mode Definition Command
Functionally, the mode definition command is used to establish the hierarchy of a network and the
characteristics of the communications line serving that network. As shown in Figure 3-5, the mode definition command contains two fields; the command type code field in BSEL2, and the mode field in
BSEL6. The mode field contains a code defining the function to be performed by the command.
With the mode definition command, the user program can designate the DMVl1 as a control station, a
tributary in a multipoint network, or as a node in a point-to-point network. In addition, the characteristics (half-duplex or full-duplex) of the physical communications line connecting the network can be
defined.
The actual mode field codes and the functions implemented by each code are listed in Table 3-4.
Under normal operating conditions, the mode definition command is issued by the user program at
start-up time (after the internal microdiagnostics have executed successfully and the run bit is set).
Network discipline requires that each DMVl1 in a network issue a mode definition command that is
appropriate to the network. For example, in a half-duplex multipoint network comprised solely of
DMVI Is:
1.

The user program at the control station issues a mode definition command with the mode
field set at four.

The user program at each tributary station issues a mode definition command with the mode
fieid set to six.

3-6

SET MASTER
CLEAR BIT
IN BSEL1
(BSEL= 10°8 )

SET
TIME OUT
COUNTER
TO
> 0.5 SEC

DIAGNOSTIC
ERROR, EXIT
TO ERROR
CONTINGENCY

EXIT TO
COMPLETE
START UP

MK-1638

Figure 3-4

Initialization of the DMVII

3-7

This network discipline also applies to DMV II s operating In point-to-point networks with other
DMVIls, DMPlls, DMClls, and DMRlls.
When tributary addresses are software assigned, the mode definition command must be used at the
controi and tributary stations to configure the network and assign line characteristics.
The functions performed by the mode definition command can also be implemented by the mode selection switches on the DMVII module. The switches must be used to establish mode definition functions
when tributary addresses are'switch assigned. The switch setting for performing the mode definition
functions corresponds to the BSEL6 codes listed in Table 3-4.
Once the type of station is set, it can only be changed by a master clear or a physical change in the
switches. If the type of station is switch assigned, a master clear has no affect. However, the switches
are overridden when the diagnostic mode bit (bit 3 of BSEL I) is set and a mode definition command is
issued.
6

7
7

•

BSEL3

4
f

RQI

1
f

•

lEO

ROO

TRIBUTARY ADDRESS

•

RDI

o
lEI

BSELO

BSEL2
SEL2

CMD .TYPE CODE
I

BSEL4
SEL4

BSEL5
I

--'-

BSEL7

MODE FIELD
I

BSEL6
SEL6

o
MK·1S39

BSEL6 Bit
Positions

0
0
0
0
I
I

0
0
I
I
0
0
1
I

0
1
0
I
0
I
0
I

1
I

Figure 3-5

Mode Definition Command Format

Table 3-4

Mode Field Codes and Functions

Line
Characteristics

Network
Configuration

DMCII-Line
Compatibility?

Half-duplex
Full-duplex
Half-duplex
Full-duplex
Half-duplex
Full-duplex
Half-duplex
Full-duplex

Point-to-point
Point-to-point
Point-to-point
Point-to-point
Control station
Control station
Tributary station
Tributary station

Yes
Yes
No
No

3-8

NjA
NjA
NjA
NjA

3.3.3 Control Command
This command is the primary means of controlling the operation of DMV II-implemented networks.
The format of the control command is illustrated in Figure 3-6.
At start-up time, the user program at the DMVII control station must issue one control command (establish tributary) for each tributary address supported in the multipoint network. This must be done
after issuing the microprocessor control and mode definition commands. This causes the microcode to
create a tributary status slot (TSS) in the DMVII data memory for each tributary in the network.
Similarly, the user program at each tributary must issue a control command (establish tributary) for
each tributary to be established at that station. This causes a TSS to be created at that station for each
tributary it establishes.
In point-to-point networks, a control command (establish tributary) must be issued at both stations. The
tributary address field in this case must be a one. This results in the creation of a single TSS structure
at each station.
The DMV II microcode at the control station and at all tributary stations uses these TSS structures to
coordinate protocol operation over the network between the control/tributary pair. User programs, at
the control station and at the established tributaries, access these structures to obtain operational information such as:
•
•
•
•

The number of messages transmitted and received;
The number of selection intervals and timeouts;
The number of reply timeouts; and
The number of various types of errors.

6
I

2
I

BSEL5
~

BSEL7
I
15

I I
(13

LATCH
POLLING
STATE
UNLATCH
POLLING
STATE

BSEL2
SEL2

DATA
I

BSELO

1
CMD TYPE CODE

. .

RDI

I
I

WRI READ/IREAD
CLR
TSS TSS
TSS
5
7
6
8

o
lEI

o . 0

RDO

TRIBUTARY ADDRESS

BSEL3

lEO

RQI

2
I

BSEL4
SEL4

DATA
I

'REQUEST KEY OR
,TSS ADDRESS
4

BSEL6
SEL6

DISABLE
COMMON
BUFFER
POOL
ENABLE
COMMON
BUFFER
POOL
MK·1840

Figure 3-6

Control Command Format

3-9

At the start-up of tributary stations having multiple software assigned tributary addresses, the user program at each station issues as many control commands as there are established tributaries at that node.
However, in networks where tributary addresses are switch assigned, only one control command specifying the switch assigned address is required as part of the start-up sequence. Any other nonzero tributary address in a control command is overridden by the switches.
The control command is also used by the user program at the control station to specify a unique set of
polling parameters for each tributary in the network.
During normal operation, the control station microcode can determine the polling level of any tributary
in the network and adjust the polling frequency of that tributary as necessary (see Section 5.2).
The control command permits the user program to perform a number of control functions using the
same command format. In general, each function implemented by this command requires issuing of a
single appropriately formatted control command. SEL6 is used to define the various functions of the
control command (see Figure 3-6). Table 3-5 provides a detailed description of each bit or field.
Table 3-5

SEL6 Control Command Functions

Bit Name

Description

0-4 Request Key

These five bits are encoded requests from the user program. When this field is
used, bits 5 through 7 must be cleared. Request keys are encoded as shown in
Table 3-6.

A control command with this bit set, allows the user program to read two consecutive locations (two bytes) of a tributary status slot (TSS) or global status
slot (GSS) without modifying it.

Read TSS/GSS

The TSS to be read is specified in BSEL3 and the location within the TSS is
specified in bits 0-4 of BSEL6. Notice that bit 5 is also set to indicate a read
GSS. To read a GSS location, BSEL3 is zero.
When the DMVll receives a control command to read a TSS or GSS location,
it passes the requested information to the user program through an information
response (see Section 3.4.3). However, the requested information is placed on
an internal queue before it is passed to the user program. As a result, the information requested may change before the user gets it. This is particularly true
for number of messages transmitted/received and selection intervals.
6

Read and
Clear TSS/GSS

A control command with this bit set, allows the user program to read and clear
specific locations in a TSS or GSS.
The TSS to be read is specified in BSEL3 and the location within the TSS is
specified in bits 0-4 of BSEL6. Notice that a read and clear command bit 6 of
BSEL6 is also set. This gives a base octal value of 100 to which the specific
I TSS address is added. To read and clear a GSS location, BSEL3 is zero.
Only the error counter sections of the TSS (7-17 octal) and GSS (15-17 octal)
can be accessed with a read and clear command.

3-10

Table 3-5 SEL6 Control Command Functions (Cont)
Bit

Name

Description
Accessing any other locations results in a procedural error.
Valid octal values for BSEL6 for the read and clear function are listed below:

Octal Value

TSS Location

107
110
111
112
113
114
115
116
117

Data messages transmitted
Data messages received
Selection intervals
Data errors outbound
Data errors inbound
Local buffer errors
Remote buffer errors
Selection timeou ts
Local and remote reply timeouts

Octal Value

GSS Location

115
116
117

Remote station errors
Local station errors
Global header blockcheck and
maintenance data blockcheck
errors
These errors are covered in
detail Section 5.3.

When the DMVl1 receives a control command to read and clear a TSS or GSS
location, it passes the requested information to the user program through an information response, and then clears the location.
As in the case of the read TSSjGSS, the information is placed on an internal
queue and is subject to change before the user gets it. However, by reading and
clearing, the user can keep a cumulative total.

Write TSS

A control command with this bit set, enables the user program to write into specific locations in an associated TSS or GSS.
The TSS to be written into is specified in BSEL3 and the specific location within the TSS or GSS is specified in bits 0-4 of BSEL6. To write to a GSS location, BSEL3 is zero.
Notice that bit 7 of BSEL6 is also set to indicate a write TSS. This gives a base
octal value of 200 to which the specific TSS address is added.

3-11

Table 3-5

Bit

Name

SEL6 Control Command Functions (Cont)

Description
The data to be written is contained in BSEL4 and BSEL5. There are eight TSS
and five GSS parameters that can be written:

TSS PARAMETER

BSEL6

Transmit delay timer (XDT)

230

Initial polling urgency (Q) and
polling rate (R) for active
state

231

7.
8.

Initial polling urgency (Q) and
polling rate (R) for inactive
state
Initial polling urgency (Q) and
polling rate (R) for unresponsive
state

233

No data message count (non-inact)
and unresponsive timeout count
(TO-UNRESP)

234

Dead timeout count (TO-DEAD)
and maximum message count (MMC)

235

Selection interval timing
counter

236

Babbling tributary counter

237

232

See Table 4-2 for details

GSS PARAMETER
1.

BSEL6

Number of sync-characters to
precede nonabutting messages

233

Preset value for streaming
tributary time counter

234

Polling algorithm update
interval (DELTA T)

235

Polling rate for dead tributaries (DEAD T)

236

Fixed polling delay (poll
delay)

237

2.
3.

See Table 4-3 for details

NOTE
Some parameters are 8-bits in length. Thus, in those
cases two parameters are indicated. All user accesses are on two byte boundaries.

3-12

Table 3-5

SEL6 Control Command FUnctions (Cont)

Bit

Name

Description

Enable
Common
Pool

A control command with this bit set allows a specified tributary (BSEL3) to use
the common receive buffer pool. Usage of the common pool is based on a common pool quota. This quota is determined for the specified tributary by adding
the octal value in BSEL4 to the current quota. If this results in a value equal to
or greater than 377 octal, a procedural error results and the quota is reset to
376. However, a tributary may be set up for unlimited use of the common pool
by setting BSEL4 to 377. Each time a tributary uses a common pool buffer, the
quota is decremented by one. When the quota reaches zero, the tributary is prevented from using the common pool. See Section 3.3.4 for more details on common buffer pool.
The common pool is checked first. If no buffers are available or the quota is
zero, or the buffer is too small, the private receive buffers are checked.

Disable
Common Pool

A control command with this bit set, disables the use of the common receive
buffer pool for the tributary specified in BSEL3.
The quota previously established for this tributary is cleared to zero.

lOII

Reserved

Unlatch Polling State

A control command with this bit set, causes the polling state level of the tributary addressed by BSEL3 to go to the active polling state. Control of the polling
activity for the specified tributary is then returned to the polling algorithm.

Latch Polling State

A control command with this bit set, establishes the polling state of the tributary addressed by BSEL3. The polling state is determined by bits 0 and 1 of
BSEL4. These bits are encoded as follow:
Bits 1 &0

Polling State

00
01
10
11

Active
Inactive
Unresponsible
Dead

3-13

Table 3-6

Request Key Field Definitions (Control Command)

Octal
Code

Name

Description

No Request

This code allows the issuing of a null control command for the purpose
of returning control of the CSRs to the DMV II. The no request code
is used when RDI is set but there is no command to issue (see Section
4.2.3). This is effectively an NOP command.

NOTE
The
enable/disable
common
pool
and / or
latch/unlatch polling state bits in BSEL 7 can be
used in conjunction with this request key.
01

Establish
Tributary

This control function initiates the creation of the tributary status slot
(TSS) data structure. This must be accomplished before any command is issued that uses a tributary address.
The user program at the control station must issue one establish tributary control command for each tributary supported in the network.
The tributary address is designated in BSEL3.

NOTE
In a point-to-point network., this control command,
with a tributary address of one in BSEL3, should be
issued at each station to establish the required TSS.
The DMV II has 12 available TSS blocks. Each block has 64 - S-bit
locations for storing status and other information necessary for maintaining communications over the data link.
As a result of establishing one or more tributary addresses, the
DMV II creates a global status slot (GSS). This GSS is part of the
overall status structure at each station.

NOTE
This control command function can also be used
during normal operation of a multipoint network to
reestablish previously deleted tributaries. In such
cases, the tributary address must be reestablished at
both the control station and the pertinent tributary
station.
NOTE
The enable / disable common pool and / or the
latch/unlatch polling state bits in BSEL 7 can be
combined with this control function in a single control command.

3-14

Table 3-6
Octal
Code

Request Key Field Definitions (Control Command) (Cont)

Name

Description

Delete
Tributary

This control function removes a specified tributary from operational
status by eliminating its associated TSS. Prior to issuing this command, the user program must first halt the tributary being deleted.
[See request key 05 (request halt state)]. The TSS can only be reestablished by using an establish tributary function. Only 12 addresses
may be established at anyone time.

Request Start-up
State

This control function initializes the designated TSS and initiates the
DDCMP start-up sequence for that tributary. BSEL3 specifies the tributary address. Request start-up state must only be issued to tributaries that are in the halt state.
When the start-up sequence is completed, the DMV 11 notifies the
user program by issuing a control response. When this response (run
state) is received by the user programs at the tributary and control
station, message traffic can begin between these two stations (see
Table 3-7).

NOTE
The enable/disable common pool and/or the
latch/unlatch polling state bits in BSEL 7 can be
combined with this control function in a single control command.

Request Maint
State

This control function places the tributary designated by BSEL3 into
the DDCMP maintenance state.
A tributary placed in the maintenance state can only transmit and receive maintenance messages. Both the control station and tributary
must be in the maintenance state in order for maintenance message
traffic to occur.
The maintenance state must only be issued to tributaries that are in
the halt state.

NOTE
The enable/disable common pool and/or the
latch/unlatch polling state bits in BSEL 7 can be
combined with this control function in a single control command.

3-15

Table 3-6

Octal
Code
05

Request Key Field Definitions (Control Command) (Cont)

Name

Description

Request Halt
State

This control function places the tributary designated by BSEL3 into
the DDCMP halt state. All outstanding buffers are returned.
When a tributary is halted at the control station, the tributary is no
longer polled. When a tributary is halted by its own user program, it
no longer responds to polling.
The TSS for the halted tributary remains unchanged at both the control and tributary stations. The halted tributary can be restarted by
issuing a request start-up state control command.
NOTE
The halt state may also be used on a global basis to
return all common pool buffers. This is accomplished by using a tributary address of zero in
BSEL3 when issuing the request halt state.
Tributaries must not be using the common pool when
this function is issued. If the common pool is in use,
a procedural error of 136 is generated (see Table 3-

7).
20

Write Modem
Control

This control function permits the user program to write the contents of
BSEL4 into the DMV 11 modem register. (See Appendix C).

Read Modem
Control

This control function causes the DMV II to read the modem register
and pass this information to the user program through SEL4 by way
of an information response. (See Appendix C.)
NOTE
Request key codes 6-17 and 22-37 are reserved.

3.3.4 Buffer Address/Character Count (BA/CC) Command
This command provides the user programs at both the control station and tributaries with the means to
assign, transmit, and receive buffers.
The format for this command is shown in Figure 3-7. Note that the command has two forms to facilitate
separate management of transmit and receive buffers. These two forms are distinguished by the type
code in BSEL2. A type code of zero is used to allocate receive buffers and a type code of four is used to
allocate transmit buffers.
The tributary address is specified by BSEL3 and the buffer address is contained in SEL4 and bits 14
and i 5 oi SEL6. The remaining 14 bits of SEL6 contain the character count in positive notation. A
character count of zero is illegal.

3-16

In addition to allocating receive and transmit buffers, the buffer address/character count command is
used to allocate common receive buffers by specifying a tributary address of zero in BSEL3. These
buffers can only be used by tributaries authorized to do so by the enable common pool bit of a control
command.
When the user program has a message to transmit, it informs the DMVll of the size and address of the
message buffer. This is done by the buffer address/character count command on a one buffer per command basis. A tributary address of zero when assigning transmit buffers results in a procedural error.
When the user program is receiving messages, it assigns receive buffers on a one buffer per command
basis using the buffer address/character count command. These buffers may be in the common pool of
buffers or be private buffers. Each SA/CC command used to assign a buffer to be the common pool
must contain a zero in BSEL3. Although this command assigns buffers to a common pool, actual allocation is performed through the control command by enabling access to the common pool on a per tributary basis.

, 6

3
I

BSEL5
B/A
17

I I

BUFFER ADDRESS
HIGH,BYTE

B/A
16

lEO

RDO

lEI

CMD TYPE

RDi

BSEL2

BSEL4
SEL4

CHARACTER COUNT
I

9
8
7
6
18 BIT ADDRESS MODE

LOW ,BYTE

BSELO

SEL2

,CODE,

BUFFER ADDRESS
LOW BYTE

CHARACTER COUNT
~IGH SIX BITS
12

ROI

TRIBUTARY ADDRESS

BSEL3

BSEL7

, 4

BSEL6
SEL6

MK-1641

7
7

6
I

BSEL3

TRIBUTARY ADDRESS

BSEL5

BUFFER ADDRESS
HIGH BYTE

BSEL7

UNUSED

RDO

•

BSEL11

.
.

lEO

UNUSED
,

CHARACTER COUNT
HIGH SIX BITS

UNUSED
15

ROI

0
T

, 5

2
I

I'IEI

CMD TYPE

22BIT1
MODE
1
BUFFER ADDRESS
LOW BYTE,

BSEL4
SEL4

,
,

BSEL6
SEL6

BSEL10
SEL10

BUS ADDRESS BITS 16-21

BSELO
BSEL2
SEL2

CODE~

CHARACTER COUNT
I
LOW BYTE I
6

RDI

22 BIT ADDRESS MODE
*TYPE CODES
BuFFER ADDRESS/CHARACTER COUNT COMMAND - RECEIVE
000
BUFFER ADDRESS/CHARACTER COUNT COMMAND - TRANSMIT = 100

MK-2512

Figure 3-7

Buffer Address/Character Count Command Format

3-17

In multipoint networks, user programs at both the control and tributary stations can handle allocation
of receive buffers in two ways:

The first method involves the allocation of receive buffers from a common pool of buffers,
With the common buffer pool enabled, receive buffers are assigned to the pool through the
buffer address/character count command on the basis of one buffer for each command issued. Each buffer address/character count command used to assign a buffer to the common
pool must contain a zero in BSEL3. Although this command assigns buffers to a common
pool, actual allocation to a tributary is done through the control command by enabling access
to the pool and assigning quotas (see Table 3-5).

I n the second method, the user program can directly allocate private receive buffers based on
anticipated message traffic using one buffer address/character count command for each private buffer allocated. In this context, a private buffer is defined as a receive buffer assigned
to a specific tributary for its exclusive use, and in all cases the address of that tributary must
be in BSEL3 of the assigning command.

Private buffers and buffers from a common pool can be used jointly at control and tributary stations in
a mUltipoint network. Under these circumstances, the advantages provided by both methods are available to the user program.
Private buffers can be set for unanticipated messages and/or abnormally large messages.

The preceding information involved standard I8-bit addressing. However, the DMVll may also operate in 22-bit addressing mode. The DMVII allows the software to set th~ 22-bit address mode of operation. The bit indicating 22-bit address mode is set by the user program as part of a command when
issuing transmit or receive buffers to the DMVII. The state of this bit is retained to indicate to the
DMV 11 the number of bits in the buffer address.

3.4

DMVll OUTPUT RESPONSES

The DMV II microcode has a set of three responses it can use to either reply to user-program commands or to inform the user program of erro'r conditions. These responses are:

•
•
•

Buffer disposition response;
Control response;
Information response.

As with input commands, each output response is identified by a typecode in bits zero, one, and two of
BSEL2.

NOTE
In multipoint networks, each response issued contains (in BSEL3) the address of the tributary that
relates to the response. However, in point-to-point
networks; equi\'al~nt r~sponses always contain a one
in BSEL3.

3-18

3.4.1 Buffer Disposition Response
This response is used to return both used and unused buffers to the user program. Figure 3-8 shows the
format of this response and identifies the five methods of message disposition in BSEL2. BSEL2 bits
zero, one, and two are encoded as follows:
Bit2

Bitt

BitO

Buffer Disposition

0
0
1
1

0
I
0
I

0
I
0
0

Receive buffer complete
Receive buffer unused
Transmit buffer complete
Transmit buffer sent but not acknowledged
Transmit buffer not sent

Receive Buffer Complete - When a message is received successfully and stored in the assigned main
memory buffer, the DMVII microcode notifies the user program by issuing a buffer disposition response with a type code of 000. Data in the receive buffer is not valid until such a response is issued.
This response is issued for both common pool and private buffers.
Receive Buffer Unused - When the protocol for a specified tributary is halted, the DMV 11 automatically returns all associated private receive buffers to the user program. To do this the DMV 11 issues a
buffer disposition response with a type code of OIl for each outstanding buffer held by the specified
tributary. This pertains to private buffers only.
7

6
I

BSEL3

1
I

RQI

BUFFER ADDRESS
HIG~ BYTE,

BIAI B/A
17
16
15

CHARACTER COUNT
HIGH 13IX BITS

lEO

llEI
CMD TYPE
CODE*

BUFFER ADDRESS
I
lOW BYTE

CHARACTER COUNT
lOW BYTE I

ROO

TRIBUTARY ADDRESS

BSEL5
BSEl7

3
I

2
I

RDI

9
8
7
6
18 BIT ADDRESS MODE
6

BSEl4
SEl4

•

BSEL5

RQI

•
ROO

RDI

I
I

UNUSED

.-t

•
14

CMD TYPE

~ODE~

UNUSED

9
8
7
6
22 BIT ADDRESS MODE

MK·1&42

I3SElO
BSEL2
SEL2

BSEl4
SEl4

BSEl6
SEl6

BUS ADDRESS BITS 16-21
1

CHARACTER COUNT
HIGH --,--SIX BITS
-.l

UNUSED

22BIT
MODE
1

lEI

BUFFER ADDRESS
lOW BYTE

•
·
..

lEO

BUFFER ADDRESS
HIG~ BYTE.

BSEl11

3
I

TRIBUTARY ADDRESS

BSEL3

BSEl7

5
I

BSEl6
SEl6

BSEL2
SEL2

7
7

BSElO

CHARACTER COUNT
J lOW. BYTE.

•

BSEL11
SEl10

* BUFFER DISPOSITION RESPONSE TYPE CODES:
1. RECEIVE BUFFER COMPLETE = 000
2. RECEIVE BUFFER UNUSED = 011
3. TRANSMIT BUFFER COMPLETE
100
4. TRANSMIT BUFFER SENT NOT ACK'd = 110
5. TRANSMIT BUFFER NOT SENT = 111

MK·2515

Figure 3-8

Buffer Disposition Response Format

3-19

The DMVII returns all common pool buffers if the user program issues a request halt state control
command with a tributary address of zero. When all common pool buffers are returned, the DMV II
issues an information response indicating that the process is finished.
Transmit Buffer Complete - When a message is transmitted successfully, the DMVll notifies the user
program by issuing a buffer disposition response with a type code of 100. Successful transmission
means that the receiving station has acknowledged receipt of the message.

Transmit Buffer Sent But Not Acknowledged - When the protocol for a specified tributary is halted, the
DMVII automatically returns all transmit buffers currently being processed by that tributary to the
user program. To do this, the microcode issues a buffer disposition response with a type code of 110 for
each buffer sent but not acknowledged.
NOTE
During protocol operation, after seven unacknowledged transmissions of a message occur, the transmit threshold error is exceeded and the DMVll issues a control response indicating this error (see
Section 3.4.2). The DMVll continues to retransmit
the message and responsibility for terminating the
transmission belongs to the user program.
Transmit Buffer Not Sent - DMV 11 maintains a queue of buffers to be transmitted for each tributary
address established in the network. When the protocol for a given tributary is halted, the DMV 11 returns all unused buffers in the associated queue to the user program. To do this, the DMVII issues a
buffer disposition response with a type code of III for each transmit buffer remaining in the queue.
The other CSRs used by the buffer disposition response are BSEL3, SEL4, and SEL6. The function of
these CSRs is as follows:
•

BSEL3 specifies the tributary address associated with the buffer disposition response.

•

SEL4 and bits 14 and 15 of SEL6 contain the I8-bit buffer address for the buffer being
completed or returned. For 22-bit address mode, bits 0-5 of BSEL6 are used with SEL4.

•

SEL6 (or SEL lOin 22-bit address mode), bits zero through 13, compose a 14-bit character
count allowing for a maximum buffer size of 16,383 bytes. A character count returned by a
buffer disposition response is designated in positive binary notation.

Protocol is halted for a tributary in one of three ways when:

The user program issues a control command halting the tributary.

A DDCMP STRT message is received while the tributary is in the run state.

A DDCMP maintenance message is received, temporarily halting the protocol, while receive
buffers are being returned.

3.4.2 Control Response
A control response is an unsolicited response issued by the DMV 11 when an error is detected or when
protocol information must be passed to the user program. The format for the control response is shown
in Figure 3-9. BSEL3 contains the tributary address or character count, SEL4 and bits 8 through 13 of
SEL6 contain the bus address for the affected buffer~ and BSEL6 indicates the type of information
being passed to the user program. In 22-bit address mode, SEL6 contains buffer address bits 16-21 and

3-20

BSEL 10 indicates the type of information being passed to the user program. These types of information
are indicated by an octal code and are listed in Table 3-7. Basically there are four categories of information.
1.
2.
3.
4.

System events
Protocol events
Network errors
Procedural errors

Table 3-7 Output Codes (BSEL6)

Octal
Code
002

Category

Information

Network
Error

Receive threshold error - This error is reported to the user program when the
number of consecutive receive errors equals seven. These receive error types
are:
1.
2.
3.
4.
5.
6.
7.

Message header blockcheck.
Message data blockcheck.
NAK in response to a DDCMP reply message.
Buffer temporarily unavailable.
Receive message overrun.
Message header format error.
When a message is too long for the
available buffer.

Each time the receive threshold error is reported, the counter is reset to zero.
004

Network
Error

Transmit threshold error - This error is reported when the number of consecutive transmit errors equals seven. These transmit errors consist of four
types and occur when:
1.
2.
3.

A STRT message is transmitted but not acknowledged within the timeout
period.
A STACK message is transmitted but not acknowledged within the
timeout period.
A NAK is received in response to a transmission with a reason code other
than REP response.
A data message is transmitted but a reply was not received within the
timeout period.

Each time a transmit threshold error is reported, the transmit error counter is
reset to zero, except when remaining in the DDCMP ISTRT and ASTRT
states.
006

Network
Error

Select threshold error - This error is reported when the selection interval timeout counter for a given station has timed out seven times. The selection interval is the time allocated for a tributary to respond to a poll or for a point-topoint station to respond to a transmission.
Each time the select threshold error is reported, the selection error counter is
reset to zero.

3-21

Table 3-7 Output Codes (BSEL6) (Cont)
Octal
Code

Category

Information

NOTE
For more information on receive, transmit, or selection threshold errors, see Section 5.3.3.

010

Protocol
Event

Start message received while running - This response indicates that a
DOCMP STRT message was received from the station specified in BSEL3
while this station was in the DDCMP run state.
In normal operation, this message is used by a control station to inform a tributary that the control station has started protocol operation for that tributary.
The start message is also used to resynchronize the logical link between a control station and tributary. This might be necessary when message traffic is inhibited because of threshold errors or receive or transmit overruns.
When the DDCMP STRT message is received: 1) the DMVll responds with
start message received while running, and 2) the protocol at the tributary halts
and all buffers are returned.
At this time the logical link may be restarted (request start-up state control
command).

012

Protocol
Event

Maintenance message received while running (or ISTRT or ASTRT) - This
response indicates that a DDCMP maintenance message was received by a
specific tributary while it was in the DDCMP run, ISTRT, or ASTRT state.
This causes the tributary to notify the user program, return all unused buffers
to the user program, and halt the protocol. The 0 MV 11 then places the tributary in the maintenance state. The message that caused this event is lost.

014

Protocol
Event

Maintenance message received while halted - This response indicates that a
DDCMP maintenance message was received by a specific tributary while it
was halted. This places the tributary in the maintenance state. The message
that caused this event is lost.

016

Protocol
Event

Start message received while in the maintenance state - This response indicates that a DDCMP STRT message was received by a specific tributary
while it was in the maintenance state. No further action is taken by the microcode. The user program determines what action to take based on this response.

022

System
Event

Tributary polling state dead - This response informs the user program at a
control station that the specified tributary polling state has gone to the dead
state.
This response has no meaning in point-to-point networks.

3-22

Table 3-7
Octal
Code

Output Codes (BSEL6) (Cont)

Category

Information

024

Protocol
Event

Run state - This response informs the user program at all stations that a specific tributary has entered the run state. The DMV 11 microcode issues this
response as a result of receiving a request start-up state control command and
having completed the DDCMP start-up sequence.

026

Network
Error

Babbling tributary - This response is issued to a user program to record the
occurrence of a babbling tributary. It is only used by half-duplex point-to-point
and multipoint control stations.
A babbling tributary is one which continues to transmit valid control messages
or message headers beyond the end of a programmable timeout (babbling tributary timeout counter).

The babbling tributary response usually indicates a malfunction at the transmitting station or too short a period for- the timeout counter.
Recovery from this error condition generally requires human intervention at
the remote station.
030

Network
Error

Streaming tributary - This response is issued to a user program to indicate
that the remote station failed to release the channel at the end of the selection
interval. It is only used by half-duplex point-to-point and multipoint control
stations.
The streaming tributary timeout period is determined by the programmable
streaming tributary timeout counter. The timeout period starts at the end of
the selection interval.
This error condition generally indicates a modem malfunction at the remote
station or an inappropriate choice of the streaming tributary timeout counter.
Recovery from this error condition generally requires human intervention at
the remote station.

32-76

Reserved

100-276 Procedural
Error

Procedural errors - This response is issued by the DMV 11 when the user program violates the procedures designated for interfacing the DMV 11. In all
cases, the event that caused the procedural error is ignored by the microcode.
All procedural errors except octal codes 140, 300, and 302 are reported immediately to the user program. Those procedural errors are placed on the response queue. Specific procedural violations are identified by the octal code in
BSEL6 as follows.

3-23

Table 3-7 Output Codes (BSEL6) (Cont)
Octal
Code

Category

iniormation

Code

Description

100

A command other than a mode definition command is issued before
the mode has been established. Control in with no request will not
return this error. Used for releasing the port.

102

Invalid type code used in a command.

104

Invalid mode change (for example, the mode of a tributary station is
changed to point-tc:rpoint).

106

A nonglobal command is issued to an unestablished tributary.

110

A nonglobal command is issued having a tributary address of zero.

112

Attempt to delete or place an unhalted tributary in the start or
maintenance protocol state.

114

Attempt to establish more than 12 tributaries.

116

Attempt to establish an already established tributary.

120

An invalid request key is used in a control command.

122

Attempt to assign a butTer for an unestablished tributary.

124

Attempt to assign a butTer for a halted tributary

126

Attempt to assign a butTer having a byte count of zero.

130

Attempt to assign a transmit butTer with a tributary address of zero.

132

Attempt to write or read and clear a reserved area of a tributary or
global status slot.

134

Attempt to use the reserved bits in BSEL7 of control command.

136

Attempt to return all common receive butTers while the common
butTer pool is being used.

140

Attempt to raise the common pool butTer quota to a value higher than
376 octal.

142-276 Reserved
300

Procedural

Buffer too small - This response informs the user program that the assigned

Error

rpf'pj"p hllffpr lC n{\t l':lrop pn{\lIon f{\r tnp f'llrrpnt lnf'{\n1ino n1PCC~OP

a....,....,,.,, . . .,,.,, """ ....

A ...........

.1&,-,""

... ""' ...

,0"" ...., ......

"'-b ........

_.a

~.&.-

-_ ...

w .....

••• _ _

······0 ···_ . . ...,-0-· Rp('{\vprv
- - - - - . _a

from this error condition is detailed in Section 4.6.2.2.
3-24

Table 3-7
Octal
Code
302

Output Codes (BSEL6) (Cont)

Category

Information

Procedural
Error

Nonexistent memory - This response is issued to the user program when the
DMV 11 microcode attempts to access a CPU memory location that does not
respond. The address that caused the error is returned in BSEL4, BSEL5, and
BSEL 7 for this response.
This error is fatal to the station that initiated the memory access causing the
error. That station must be halted and restarted (see Section 4.6.2.1).
NOTE
With the exception of the buffer too small and nonexistent memory errors, the only control response
fields used by the DMVll when posting a procedural error are the type code field in BSEL2, and
the output code field in BSEL6. All other fields remain as set by the user program in the command
that originally generated the procedural error.

304

System
Event

Modem disconnected - This response informs the user program that an on-tooff transition of the EIA signal data set ready (DSR) was detected. Such a
transition indicates that the modem is disconnecting from the communications
line.
Since this is a global response, the content of BSEL3 is zero.
When BSEL 7=304, modem clear to send failure: (CTS) global response. Informs
user program that CTS failed to set after asserting request to send (RTS), or
CTS has gone from an ON to OFF transition while transmitting.

306

System
Event

Queue overflow - This response indicates that the free linked list is empty (see
Section 4.6.2.3).
This error typically indicates that for some reason output responses are being
called for faster than the microcode can process them.
NOTE
This is a global fatal error and the DMV 11 initializes itself after attempting to return all information (response queue only).
Once this response is issued, the user program has three seconds to retrieve the
next pending response from the CSRs. Three seconds are allowed for each
pending response before the internal microdiagnostics clear the CSRs (see
Section 4.3 for restarting).

310

System
Event

Modem carrier loss - This control response code informs the user program
that the EIA signal carrier detect has gone from on to off while the DMV 11
was in the process of receiving a message. Since this is a global response, the
content of BSEL3 is always zero.

3-25

2
I

RQI

lEO
I

RDO

TRIBUTARY ADDRESS

BSEL3

2
I

RDI

lEI

22BIT
0
0
MODE CMD TYPE CODE
0

BSEL5

BSEL7
I

• BUS ADDRESS OR CHARACTER
~OUNT HIGH BYTE
I

EVENT/ERROR
CODE
I
I

·BUS ADDRESS BITS 16-21
I

BSEL2

SEl2
BSEL4

• BUS ADDRESS OR CHARACTER
COUNT LOW BYTE
I

BSELO

SEL4
BSEL6
SEL6

18 BIT ADDRESS MODE
·ONLY APPLICABLE FOR NON-EXISTENT MEMORY
AND BUFFER TO SMALL ERRORS
MK-2510

Figure 3-9

3.4.3

Control-Out Command Format

Information Response

An information response is issued by the DMV 11 microcode in reply to a request for information by the
user program. The format for this response is shown in Figure 3-10. The type code for this response is
010 binary as indicated in BSEL2. BSEL3 contains the tributary address and SEL4 contains the information requested by the user program. If the information requested is from a GSS, BSEL3 contains a
zero.
An information response contains a return key code or a TSS or GSS address in BSEL6 bits 0-4. The
return key codes are used in response to control request keys or protocol events and are encoded as
shown in Table 3-8. The TSS address is used in response to a read or read and clear TSS/GSS command in conjunction with bits 5 and 6 of BSEL6.
Information responses to read or read and clear TSS/GSS control commands, use the TSS address
field (bits 0-4 of BSEL6) to indicate the TSS or GSS location read. Bits 5 and 6 indicate whether the
response is to a read or read and clear input command.

3.5 TSS/GSS ACCESS
When a user program accesses a TSS or a GSS through a control command, the DMV 11 reads the
designated location and passes the data to the user program by means of an information response.
Reading a TSS or GSS location results in two bytes of data from that location being stored in BSEL4
and BSEL5 of the information response, with the low-order byte in BSEL4, and the high-order byte in
BSEL5. If a TSS is being read, BSEL3 in the information response contains the associated tributary
address. However, data read from a GSS is passed to the user program through an information response
having a zero in BSEL3.
As described in Table 3-5, any TSS or GSS location can be read, and specific locations can be read and
cleared. Along with the TSS/GSS address, BSEL6 in an information response also contains two singlebit fields that jndicate a read or a read and clear TSS/GSS. These information response fields are
described in detail below.
TSS/GSS address

This field (BSEL6, bits zero to four) contains the octal address of the
TSS/GSS location from which the data in BSEL4 and BSEL5 is read.

Read TSS/GSS

When set, this bit (BSEL6, bit five) designates that BSEL4 and
BSEL5 contain the data requested by the read TSS/GSS control com_~_.J

Uld.llU.

3-26

When set, this bit (BSEL6, bit six) designates that BSEL4 and BSEL5
contain the data requested by the read and clear TSS/GSS control
command. In addition to reading the requested TSS/GSS location, the
DMV11 also clears that location.

Read and clear TSS/GSS

NOTE
The TSS/GSS locations accessible for writing,
reading, and reading and clearing, are listed and described in Table 3-5.

7
7

6
I

5
I

TRIBUTAR\, ADDRESS

BSEL3
I
I

RQI

I
I

•

BSEL2
SEL2

•

IREAD READ
CLR TSS
TSS

1
0
0
CMD TYPE CODE

BSEL4
SEL4

DATA

NOT USED
15

BSELO

BSEL6
SEL6

'RETURN KEY OR I
.TSS ADDRESS
I

BSEL7

lEI

RDI

ROO

. .
I
I

lEO

DATA

BSEL5

o
MK·2391

Figure 3-10
Table 3-8
Octal
Code

Information Response Format

Return Keys for Information Response

Name

Description

Return Modem
Status

This code indicates that BSEL4 and BSEL5 contain the requested modem
status (see Appendix C).

Buffer Return
Complete

This code indicates that the process of returning all buffers is completed.
Buffers are returned to the user program under the following circumstances:
1. The protocol event STRT message received while running occurred.
This causes all private buffers assigned to the tributary designated by
the address in BSEL3 to be returned.
2. The protocol event maintenance message received while running
occurred. This causes all private buffers assigned to the tributary
designated by the address in BSEL3 to be returned.
3. The user program issued a control command containing the request key
request halt state causing all private buffers assigned to the tributary
designated by the address in BSEL3 to be returned.
4. The user program issued a global control command (BSEL3 = zero)
containing the request key request halt state. This causes all unused
common pool buffers to be returned.
Information responses containing the return key code for buffer return
complete always have zeros in BSEL4 and BSEL5.

3-27

CHAPTER 4
PROGRAMMING TECHNIQUES

4.1 INTRODUCTION
Proper design of user programs for operation with DMVll-based multipoint and point-to-point networks requires that consideration be given to a number of programming topics. This chapter discusses
the following programming topics.
•
•
•
•
e

•

Command discipline and handshaking;
DMVII start-up;
Criteria for determining user-defined parameters;
Error counter access;
Error recovery procedures;
Booting a remote station.

These programming topics deal with interfacing the user program and DMV 11 microcode by using the
DMV 11 command/response structure.
4.2 COMMAND/RESPONSE DISCIPLINE AND HANDSHAKING
The command/response interface between a DMVII and the user program is accomplished through
the DMVII CSRs that are addressed through the CPU I/O page.
Since the DMV 11 runs in a multiprocessing mode with the associated CPU, the passing of commands
and responses through this interface must be highly disciplined to eliminate the possibility of a race
condition (the user program setting bits in the CSRs after the microprocessor has read those bits). This
interface discipline requires that the user program follow two separate procedures; one for issuing commands, and one for retrieving responses.
Figure 4-1 illustrates the control bits involved in CSR interface discipline. These bits are located in the
DMV 11 CSRs BSELO and BSEL2. Examination of Figure 4-1 shows that BSELO contains two control
bits named interrupt enable in (lEI) and interrupt enable out (lEO), bits zero and four respectively.
These bits when set, serve to enable the microprocessor to interrupt the main CPU under two circumstances:
1.

When the CSRs become available for the issuing of a command after access is requested by
the user program for that purpose (lEI and RDI).

When the microcode has a response to be retrieved from the CSRs by the user program (lEO
and RDO).
NOTE
Interrupt mode must be used, otherwise, receive
overruns and transmit underruns are very probable.

4-1

NOTE
It is recommended that the interrupt enable (lEI
and lEO) bits be set when interfacing with the
CSRs. It is imperative that they be set when
operating at 56K b/s because the microprocessor
is halted momentarily on every access to the
CSRs.
The procedures described below defining CSR interface discipline are based on operation in the interrupt mode. As a consequence, the lEI and lEO bits should be set by the user program prior to using the
CSR interface.
6

RQI

lEO

ROO

RDI

o
lEI

BSELO
BSEL2
MK-2390

Figure 4-1

CSR Interface Control Bits

4.2.1 Command Discipline
At start-up time, before the user program can execute any command, it must initialize the DMVII.
This is accomplished by the program setting the master clear bit in BSELI and waiting for the DMVII
to set the run bit.
Once the DMV 11 is initialized, commands may be issued. All commands are issued by the user program in two successive steps. The first step requests the use of the data port. The second step identifies
the command type and the data port information for the appropriate command, and notifies the
DMVII that the command is in the CSRs. The specific content of each data port is further defined
under each command description in Section 3.3. The handshaking procedure for input commands is as
follows (see Figure 4-2).
•

The user program requests the use of the data port to issue a command by setting request in
(RQI) bit 7 of BSELO. The user should also set bit 0 of BSELO, interrupt enable in (lEI), at
the same time (using the same instruction) to allow the DMVII to interrupt the CPU when
the data port is available. An interrupt is generated to XXO when RDI is asserted by the
DMVII.
NOTE
The 22-bit mode is used when the software supports
22-address bit buffers. A "one" in bit 3 of BSEL2
indicates to the DMV 11 that the software supports
the change in the command format required to support 22-address bits.

•

When the data port is available, the DMVII informs the user by setting ready in (bit 4 of
BSEL2) and generating an interrupt to vector XXo.

•

On detecting RDI bit set, the user can: 1) load the appropriate information into SEL4 and
SEL6, and 2) load the input command code into bit 0-2 of BSEL2.

•

If a single command is to be issued, the user program clears RQI. If a series of commands
are to be issued, RQI can remain set until just prior to the loading of the last command into
the CSRs. By leaving RQ! set while issuing a series of commands~ the user program is assured of having access to the CSRs after the next response.

4-2

4.2.2

Retrieving Responses

The OMVII issues responses in two steps. If ROI is not set, the data pertinent to the responses being
issued is loaded into BSEL3, SEL4, and SEL6. Once this is complete, the DMVll sets the ready out
(ROO) bit and the command code in BSEL2. An interrupt through vector XX4 is generated if the lEO
bit is set. Generally, processing an output response involves the following steps:
•

The user program checks for ROO set. This is done by waiting for an interrupt.

•

To use the output interrupt capability, the user program must set the output interrupt enable
bit in BSELO immediately after it detects that the run bit has been set following master
clear.

•

When an ROO set condition is detected, the user program should move the contents of
SEL2, SEL4, and SEL6 into a working storage area and clear ROO in BSEL2 as soon as
possible. When ROO is cleared, the data port (SEL4 and SEL6) is released to the OMVI i
for more input or output processing.

4.2.3 CSR Interface Interactions
User-program access to the CSRs is under complete control of the OMV 11 microcode. Access to the
CSRs is granted upon request when the user program has a command to issue, or when the microcode
has a response for the user program. Figure 4-2 illustrates the nature of the access window available to
the user program under interrupt control, when issuing a command, or retrieving a response. As previously indicated, the user program requests use of the CSRs for the purpose of issuing a command by
setting RQI. The OMVll microcode makes the CSRs available for the issuing of a command, only
when it is not using them, by setting ROI and interrupting the user program through the floating vector
XXO. As a result, the time period between the setting of RQI by the user program and the granting of
the CSRs through an interrupt is indeterminate.
When commands are being issued from a queue, and the last command has been issued with the user
program still having ownership of the CSRs (ROI is set), there is a mechanism for returning the CSRs
to the OMVll. In such cases, the user program can issue a control command with the code for no
request in the request key field, thereby, signalling the microcode to ignore the contents of the CSRs.
In this way, the possible reading of erroneous data by the OMVl1 microcode is avoided.
If the user program is to issue a single command, RQI should be cleared prior to issuing the command
to the CSRs, as indicated in Figure 4-2. However, if a series of commands are to be issued, the user
program can leave RQI set. In this circumstance, when a command is issued and ROI is cleared, the
microcode relinquishes the CSRs to the user program as soon as they become available. The time period between clearing ROO upon completing one command, and an interrupt initiating the next command, is also indeterminate.
When the OMVll has a response to be passed to the user program, it sets ROO then interrupts the
main CPU through the floating vector XX4. At this point, the user program has ownership of the CSRs
and can proceed by reading the response. Once the response is read from the CSRs, the user program
should immediately clear the RDO bit. User-program routines responsible for issuing commands and
retrieving responses should limit the CSR access time required to load a command or retrieve a response.

4.3

DMVll START-UP

Starting a OMVII requires that the user program perform a series of steps to; 1) configure the OMVII
to operate within the context of the associated network, 2) establish user-defined parameters, and 3)
initiate protocol operations at the OMVll.

4-3

USER
SETS
RQI

USER CLEARS RQI
, NO FURTHER COMMANDS
TO ISSUE

* DMV11
SETS
RDI

USER CLEARS RDI TO
.....- - - - - - - - - - - -... NOTIFY DMV11 THAT COMMAND
USER HAS TOTAL CONTROL OF CSRs HAS BEEN ISSUED
-~---~ TO ISSUE COMMAND
(lEI)

*DMVll
SETS
ROO
(lEO)

* USER CLEARS ROO TO
,..-_ _ _ _ _ _ _ _ _ _ _ _ _ _...... NOTIFY DMVll THAT
USER HAS TOTAL CONTROL OF CSRs
TO RETRIEVE RESPONSE

RESPONSE HAS BEEN RETRIEVED

* DMVll HAS OWNERSHIP OF CSRs
MK-2514

Figure 4-2

4.3.1

CSR Access Window

Configuration Procedure

The sequence to configure a DMV 11 control and tributary station for network operation is formed by
the following steps:

4.3.2

Set the master clear bit and wait for the run bit to set. (See Section 3.3.1).

When the run bit is set, read BSEL4 and BSEL6.

If the contents of BSEL4 equals octal 33, and the contents of BSEL6 equals octal 305, the
start-up diagnostics have successfully executed and the DMV 11 is running. Any other value
in BSEL6 indicates that an error condition was detected by the start-up diagnostics. The values and meanings of these diagnostic error codes are listed in Table 4-1.

If the DMV 11 operational mode is software selectable, set the mode for that device by issuing the appropriate mode definition command (see Section 3.3.2). If the mode for the
DMV 11 is selected by internal switches, this step can be ignored.

Specifying User-Defined Parameters

After a DMV 11 is configured, the user parameters are specified. User-defined parameters include parameters used by the polling algorithm, and parameters specific to protocol operation. In addition,
those user parameters that are specific to the operation of tributaries, are stored in the tributary status
slot (TSS) associated with each tributary_ Parameters that are pertinent to overall system operation are
stored in the global status slot (GSS) for the control or tributary station.

4-4

Table 4-1

Diagnostic Error Codes

BSEL6

BSEL4

Description

101

N/A

Branch test has failed and the microcode is spinning in a loop.

102

N/A

6502 internal resister test has failed and the microcode is spinning in a loop.

103

N/A

Load and store instructions test has failed and the microcode is spinning in a
loop.

104

N/A

Compare instructions test has failed and the microcode is spinning in a loop.

105

N/A

Increment and decrement instructions test has failed and the microcode is
spinning in a loop.

106

N/A

Shift and rotate instructions test has failed and the microcode is spinning in
a loop.

107

N/A

Logic instructions test has failed and the microcode is spinning in a loop.

110

N/A

Add with carry, subtract with carry, set and clear decimal mode instructions test has failed and the microcode is spinning in a loop.

III

N/A

Stack push and pull instructions test has failed and the microcode is spinning in a loop.

112

N/A

Subroutine instructions test has failed and the microcode is spinning in a
loop.

113

N/A

Ram scratchpad, CSR, and NPR address resisters addressing test has failed
and the microcode is spinning in a loop.

114

N/A

Ram scratchpad, CSR, and NPR address resisters data test has failed and
the microcode is spinning in a loop.

115

N/A

True interrupt test has failed and the microcode is spinning in a loop.

116

N/A

Ram data and addressing test has failed and the microcode is spinning in a
loop.

117

N/A

Ram alternating data test has failed and the microcode is spinning in a loop.

120

N/A

Indexed indirect addressing mode instruction test has failed and the microcode is spinning in a loop.

121

N/A

Line unit message test has failed and the microcode is spinning in a loop.

305

The microdiagnostics have completed without errors.

4-5

As described in Section 3.3.3, user parameters are specified through control commands configured to
address a TSS or a GSS. These control commands write the data contained in BSEL4 and BSEL5 into
the locations specified by bits 0-4 of BSEL6 (TSS or GSS address). In establishing polling and protocol
parameters, the user program has the option of accepting the default for a parameter or setting the
parameter to some predetermined value. Chapter 5 details the criteria to be used in determining optimum values for the various polling parameters. Criteria for determining the remaining parameters,
which generally concern the operation of the communications link, are presented in Section 4.6.
NOTE
Although the majority of user-defined parameters
are t 6-bits in length, some are single byte parameters. If the user program wishes to change one of the
single-byte parameters and accept the default for the
other, both parameters must be written. This is necessary because both TSS and GSS user-defined parameters are written on 2-byte boundaries.
The process of establishing user-defined parameters is presented as two separate steps:
1.

Specifying user-defined parameters for control and tributary station TSS structures.

Specifying user-defined pa-rameters for control and tributary station GSS structures.

4.3.2. t Specifying TSS Parameters - TSS parameters that can be specified by the user program are
listed in Table 4-2 by name, BSEL3 address, size, and default value. A functional summary of each
parameter is also given. The actual order of setting TSS parameters through appropriately configured
control commands is arbitrary. The complete command series to specify these parameters for TSS
structures at a multipoint control station is listed below:
1.

Issue a series of control commands to set the value for the transmit delay timer. This is referred to as the preset value.

Issue a series of control commands to establish the polling parameters Q and R for the three
polling levels.

Issue a series of control commands to specify values for the active, inactive, unresponsive,
and dead polling state-change parameters.

Issue a series of control commands to specify values for the maximum transmitted message
count.

Issue a series of control commands to set the selection timers for tributaries (or issue a single
command to set the point-to-point station reply timer).

Issue a series of control commands to set the babbling tributary timers.

4-6

Table 4-2

User-Defined TSS Parameters

Name

TSS Addr
(Octal)
BSEL6

Size
(Bits)

Default
(Octal)

XDT
PRESET

230

Q (Active)
Q (Inactive)
Q (Unresp)

231
232
233

8
8
8

377
0
0

R (Active)
R (Inactive)
R (Unresp)

231
232
233

8
8
8

0
100
20

Description
Preset value for
the transmit delay
timer. This parameter provides a
fixed delay between
transmission of data
and maintenance
messages. The default value of 0 =
no delay.

The initial value of
polling urgency (U)
for the tributary:
The TSS for a tributary must be assigned a Q value for
each of the three
activity levels;
active, inactive,
and unresponsive.
This parameter is
applicable only to
TSS structures at
the control station.
The rate (R) by
which the urgency
(U) is increased for
the tributary.
The TSS for the tributary must be
assigned an R value
for each of the
three activity
levels; active, inactive, and unresponsive. Both the
Q and R for a given
tributary are established through a
single control command. Therefore, if

4-7

Table 4-2

Name

TSS Addr
(Octal)
BSEL6

User-Defined TSS Parameters (Cont)

Default
(Octal)

Size
(Bits)

Description
one parameter is to
be set to a unique
value, and the default is to be accepted for the
other, both the default value and the
unique value must be
written. This parameter is applicable
only to the TSS
structures at the
multipoint control
station.

NDM-INACT

234

Number of no data
messages required to
go inactive: This is
the number of consecutive polls to be
made (without receiving a data message) before changing the activity
level of that tributary from active to
inactive. This parameter is applicable
only to the TSS
structures at the
control station.

TO-UNRSP

234

Number of timeouts
to go unresponsive:
The number of consecutive polls of a
tributary (without
response) before
changing the activity level of that
tributary from active or inactive to
unresponsive. Both
the NDM-INACT and
TO-UNRSP counts are
established through
a single control

4-8

Table 4-2

Name

TSS Addr
(Octal)
BSEL6

User-Defined TSS Parameters (Cont)

Size
(Bits)

Default
(Octal)

Description

command. Therefore,
if one parameter is
to be set to a
unique value, and
the default is to be
accepted for the
other, both the default value and the
unique value must be
written. This parameter is applicable
only to the TSS
structures at the
multipoint control
station.
TO-DEAD

235

Number of timeouts
to go dead: The number of consecutive
polls of an unresponsive tributary
(consecu ti ve selection timeouts) before the activity
level of that tributary is changed from
unresponsive to
dead. This parameter is applicable
only to the TSS
structures at the
multipoint control
station.

MXMC

235

Maximum transmitted
message count: This
parameter is a count
of the maximum number of abutting data
messages to be
transmitted by a
station before it
deselects itself.
This count applies
to the TSS structures at both control and tributary

4-9

Table 4-2

Name

TSS Addr
(OctaD
BSEL6

User-Defined TSS Parameters (Cont)

Size
(Bits)

Default
(Octal)

Description
stations in multipoint networks as
well as point-topoint stations. Both
TO-DEAD and MXMC
for a given tributary are established
through a single
control command.
Therefore, if one
parameter is to be
set to a unique
value, and the default is to be accepted for the
other, both the
default value and
the unique value
must be written. At
tributary and pointto-point stations,
the polling parameter TO-DEAD is ignored.

SEL
TIMER

236

3 (seconds)
(454 Octal)

4-10

Selection interval
timer: This timer
is started when a
message is transmitted with the
select flag set, and
halted when a valid
reply is received or
the line is resynchronized. The selection timer is used
as a reply timer for
full-duplex pointto-point networks
(see Section 4.4.1).
It is used as the
select timer at multipoint control stations, and in halfduplex point-topoim networks. Thi~

Table 4-2

Name

TSS Addr
(Octal)
BSEL6

User-Defined TSS Parameters (Cont)

Size
(Bits)

Default
(Octal)

Description
counter counts in 10s
of milliseconds (ms)
from 10 to 655,350 ms.

BAB
TIMER

237

6 (seconds)
(1130 Octal)

Babbling tributary
timer: This timer
is used to detect
a babbling tributary (see Section
4.4.2). In a
multipoint network
this parameter is
applicable only to
the control station.
However, this parameter is applicable
to both stations in
point-to-point networks operating
half-duplex.

4.3.2.2 Specifying GSS Parameters - As previously indicated, when one or more tributary addresses are
established at a DMV 11, the DMV 11 's microcode automatically creates a GSS for that control or
tributary station. The GSS parameters that can be specified by a user program are listed in Table 4-3 by
name, BSEL3 address, size, and default value. A functional summary of each parameter is also given. If a
value is not specified for a parameter the microcode uses the default value. Specifying a user-defined GSS
parameter requires that BSEL3 in the pertinent control command contain zero. The control commands
necessary to specify GSS parameters for a multipoint station are listed below:
1.

A control command to specify the number of sync-characters (NUM SYNC) that are to precede nonabutting transmit messages.

A control command to set the streaming tributary timer.

Three control commands to establish values for the global polling parameters delta time
(DELTA T), dead tributary (DEAD T), and poll delay, respectively.

Specific user-defined TSS and GSS parameters are common to both control and tributary stations.
Note that control commands specifying TSS parameters must have the address of the tributary associated with the TSS being accessed in BSEL3. Similarly, each control command specifying a GSS parameter must have BSEL3 set to zero. Since the prior steps have covered user-defined TSS and GSS

4-11

parameters (see Table 4-2 and 4-3) at the control station, the two steps listed below complete the parameter-specifying process at the tributary stations:
1.

Issue a series of control commands at each tributary station to set the maximum transmitted
message count (~v1XMC) fOi each active TSS in a tributary station TSS structure. Note that
the 8-bit value for MXMC must be placed in BSEL5 of each command (the tributary station
microcode ignores BSEL4 in these commands). The procedure for determining an optimum
value of this parameter for tributary stations is the same one used for control stations.

Issue a single control command at each tributary station to set a value for the number of
sync-characters (NUM SYNC) that are to precede nonabutted transmit messages. The procedure for determining an optimum value of this parameter for tributary stations is the same
one used for control stations.

Table 4-3

Name

GSS Addr
(Octal)
BSEL6

User-Defined GSS Parameters

Size
(Bits)

Default
(Octal)

Description

NUMSYNC

233

12 (low
speed)
17 (high
speed)

Number of sync-characters:
This global value specifies the number of synccharacters that are to
precede nonabutting transmitted messages. This
parameter applies to all
stations. Low speed is
defined as less than 19.2K
bls and high speed is 19.2K
and above b/s.

STREAM
TRIB

234

6 (sec.)
(1130
Octal)

Streaming tributary timer
preset: This timer is used
to detect a streaming tribu tary (see Section 4.4.3)
and Table 3-7). In a multipoint network, this
parameter is applicable
only to the control station. However, in pointto-point networks, this
parameter is applicable to
both stations.

DELTA T

235

200 (ms)
(24
Octal)

Delta time: This is the
polling algorithm update
increment. This global
parameter, which is applicable only to multipoint control stations,
is used by the polling

4-12

Table 4-3

Name

GSS Addr
(Octal)
BSEL6

User-Defined GSS Parameters (Cont)
Size
(Bits)

Default
(Octal)

Description

algorithm to calculate
polling urgency (see
Section 5.2.1). The default value of 200 ms is
the minimum value fOi this
parameter. DELTA T is also
used as the interval for
updating the transmit
delay timer.
DEADT

236

10 (sec.)
(1750
Octal)

Dead timer: This is the
interval between polls for
dead tributaries. This
global parameter applies
only to multipoint control
stations.

POLL
DELAY

237

o(no

This parameter provides
for a fixed delay between
polls for all tributaries
in a network. I f the default is accepted, the
next poll for any tributary occurs immediately
following the current
poll.

delay)

4.3.3 Protocol Operation
At this point the DMV 11 has been configured for operation in the associated network and is ready for
protocol operation. The steps required to initiate protocol operation are:
1.

Place established tributaries in the ISTRT state by issuing one control command containing
the request key. Request ISTRT state for each tributary address.

If the DMV 11 is a station in a point-to-point network, one control command must be issued
containing the request ISTRT state request key with a tributary address of one in BSEL3.

The DMVII confirms that the protocol is operational at each tributary by issuing a control
response (one for each control command issued) containing the protocol event code for
DDCMP run state entered.

4.4 CRITERIA FOR DETERMINING COMMUNICATIONS LINK PARAMETERS
User-defined TSS and GSS parameters fall into two categories: polling parameters that provide for
user-program control over the dynamic activity of the polling algorithm, and communications link pa-

4-13

rameters that provide the user program with the ability to regulate data traffic over the physical communications line. Referring to Tables 4-2 and 4-3, the communications link parameters include:
•
•
•
•
•
•

Selection interval timer,
Number of sync-characters,
Babbling tributary timer,
Maximum transmitted message count,
. Streaming tributary timer,
Transmit delay timer.

Values for the selection interval timer and the number of sync-characters are interrelated, as are values
for the babbling tributary timer and the maximum transmitted message count. These interrelated parameters are described in Sections 4.4.1 and 4.4.2.
4.4.1 Setting the Selection Interval Timer
The function performed by the selection interval timer at a DMV 11 depends on the mode selected fof'
that DMV 11. In full-duplex point-to-point networks, this timer is used as a reply timer for the purpose
of message accountability. This timer serves as a selection interval timer when the mode for the associated DMV 11 is one of the following:
•
•
•

A full-duplex control station;
A half-duplex control station;
A half-duplex point-to-point station.

In this capacity, it performs the link management function and provides for message accountability.
Link management is the process of controlling the transmission and reception of data over networks
where there are two or more transmitter/receiver devices actively connected to the same physical communications link. This applies to half- and full-duplex multipoint networks as well as half-duplex pointto-point links. On half-duplex links, only one transmitter can be active at any time, and on full-duplex
links, only one slave transmitter can be active at a time.
A station on such links can transmit when it is selected or granted ownership of the link. Link ownership
is passed through use of the select flag in the ODCMP message header. Detecting a select flag in a
received message allows the receiving station to transmit after message reception is completed. Sending
a select flag means that the transmitting station ceases transmitting after the current message is sent.
A selection timer detects the loss of a select flag by timing the interval required to receive the longest
message from a station. A timer is started when a station is selected and reset when valid messages are
received from that station. When the timer interval is exceeded at the sending station (a message was
not received during the period of the timer) it is assumed that messages with the select flag were either
transmitted or received in error.
At this point, the station that originally sent the messages with the select flag set assumes ownership of
the link. This station resumes transmitting as if, it had received a valid select return.
The values assigned to select interval timers at stations in half-duplex point-to-point networks should be
different at both stations to avoid possible deadlock race conditions. For both multipoint control stations
and half-duplex point-to-point stations, the criteria for determining the value for a select timer includes
such factors as:
•
•
•
•
•

Maximum message length;
Number of sync-characters;
Line speed;
Line turnaround time:
Message processing delays.

4-14

As indicated in Table 4-3, the GSS parameter number of sync-characters has two defaults; one for lowspeed operation (I 0), and one for high-speed operation (15). The operational speed range of a DMV 11 is
specified by the line unit low-speed/high-speed switch which is placed in the appropriate position when the
DMV 11 is hardware configured (see Section 2.5). In the low-speed position the DMV 11 can operate at line
speeds up to I9.2K bls, and in the high-speed position the device line speed is 19.2K and greater b/s. It is
recommended that the default for the appropriate line speed range be taken for this parameter.
Some recommended values for a selection interval timer are given in Table 4-4. The calculations shown
in Table 4-4 include the following overhead factors:
256 bytes of data
28 bytes of header, sync, and pad characters
Total

284 bytes

The formula used to derive the values listed in Table 4-4 is:
8 bits per byte
X

284 bytes per message + RTS/CTS delay = Timer value (in seconds)

baud rate (bits
per second)
NOTE
Most modems include an RTSICTS delay-that must
be included in the calculation of the value for the selection interval timer. When operating with an external (EIA) modem, the typical delay used is 150 ms.
The delay used when operating with the integral
modem is 100 /-LS.
Table 4-4

Recommended Selection Interval Timer Values

Bits Per Second

Calculated Timer Value for a 256 Byte Message

4.8K

473 ms + 150 ms = 623 ms (700 ms)

9.6K

236 ms + 150 ms = 386 ms (400 ms)

56K

40.5 ms + 0.1 ms = 40.6 ms (50 ms)

The values listed in Table 4-4 represent absolute minimums. In most cases, specific applications require
additional delay time over these values to prevent a timeout during reception of a valid message. Requirement for additional delay time can be caused by processing delays that occur when receiving from
a non-DMV II device, or by line delays encountered when dealing with satellite networks. When determining this value, keep in mind that it represents the time the system can reasonably expend waiting for
a response from another station.
When used as a reply timer, the selection interval timer sets the maximum waiting period between sending a message and receiving an acknowledgement before taking error recovery actions. This timeout is
necessary to recover from outages and the distortion of messages by the link. This timeout also prevents
the protocol from being deadlocked.

4-15

The same criteria used to determine a value for a selection interval timer in multipoint networks, are
also used to determine a value when this timer is used as a reply timer. As shown in Table 4-2, the
default value for both cases is three seconds.
4.4.2 Setting the Babbling Tributary Timer
This user parameter is applicable to half-duplex and full-duplex multipoint network control stations. A
babbling tributary is a tributary that continues to transmit valid DOCMP messages after a programmable
timeout has expired, thereby, denying equal access to other nodes. This situation is controlled by the
babbling tributary timer which monitors the total time period a tributary continuously transmits without
relinquishing the communications line. When this period exceeds the timeout period of the babbling
tributary timer, the user program is notified through a control response. The control response contains the
code for a babbling tributary along with the identity of the offending tributary. When a babbling tributary
is detected, the control station takes no action beyond this notification.
A major consideration in determining a value for the tributary timer is the total time interval that a
given tributary requires to end a selection interval. Determining the value for this timer is similar to
that for the selection interval timer because the same range of factors are used as criteria for calculating the value. The main difference in the two determinations is that the total number of message
bytes should be used in babbling tributary timer parameter calculations rather than the number of
bytes in the longest message.
A value for the maximum transmitted message count parameter must also be considered in conjunction
with the parameter for the babbling tributary timer. The user-defined parameter to set this counter
places a limit on the number of messages that a tributary can transmit during the selection period. This
is done by forcing the select flag when the count of messages received from a tributary equals the value
of the maximum transmitted message count. This count relieves the user program from having to limit
the number of messages queued for transmission in order to avoid a babbling tributary condition.
In any case, the period established for the timeout of a babbling tributary timer should be long enough
In addition, the parameter assigned to the maximum transmitted message count should also be considered when establishing the period of the babbling tributary counter.
~o ensure that timer expiration definitely indicates an error condition.

4.4.3 Setting the Streaming Tributary Timer
A streaming tributary is a tributary station on a multipoint line (or an associated point-to-point station)
that continues to assert the carrier signal on the link after it has relinquished ownership of the link. In
normal operation, ownership of the link is returned to the control station when it receives a select flag or
the period of the selection interval timer is exceeded. A timeout of the streaming tributary timer indicates a potential jamming of the link by a defective tributary station, a defective point-to-point station, or a malfunctioning modem.
The streaming tributary is started when ownership of the link is granted to the control station by the
remote station, and stopped when the carrier is dropped by that station. When a streaming tributary is
detected, through expiration of the streaming tributary timer, the user program is notified in the same
manner as with a babbling tributary. The control station does not transmit until the carrier is dropped.
Determination of a value for the streaming tributary timer requires consideration of such factors as
settling time of the communications line and modem delays. As with determining periods for the selection interval timer and the babbling tributary timer, the period specified for this timer should be long
enough to preclude premature expiration of the timer. For most network applications the default of one
second is sufficient.

4-16

4.5 ERROR COUNTER ACCESS
The DMVII is equipped with a large compliment of error counters designed to isolate a wide range of
error conditions. The TSS for each established tributary contains seven error counters along with three
statistical counters that provide background information for error analysis. In addition, the GSS at each
station contains four error counters that tabulate errors that are global to the station. The three TSS
statistical counters are 16 bits in length, and the threshold error counters are three bits in length. The
remaining TSS/GSS error counters are eight bits long.
4.5.1 Reading the Counters
Both TSS and GSS counters are accessed through an appropriate control command with the content of
the requested counter or counters being returned through an information response (see Sections 3.3 and
3.4). Through the control command~ the user program has the option of reading, or reading and clearing
the counters. When doing error analysis it is recommended that a user program read and clear these
counters to assure a zero-base for subsequent sampling of the counters. If copies of the counters are
being maintained in main CPU memory, it is also recommended that counters be read and cleared.
NOTE
The three-bit threshold error counters are automatically reset when the maximum count is reached so
that access to these counters is restricted to reading
only.
The DMVII error and statistical counter structure is designed to be complimentary. As an example of
this complimentary structure, consider the data errors inbound counter and the d~ta messages received
counter. The data errors inbound counter tabulates the errors related to the validity of message reception such as block-check errors, whereas, the data messages received counter records the total number
of messages received. A ratio of message reception errors to total number of messages received can be
derived from these two counters.
4.5.2 Counter Skew
When performing error analysis, there is a potential of skew between counts due to read time lags and
the requirement that counters be read one at a time. The probability of skew between counts is a function of line speed; the higher the line speed, the greater the probability of a skew condition. An example
of this potential skewing is the possible discrepancy between the number of selection intervals and the
number of selection timeouts. A skew could result from additional selection timeouts occurring while
the counters are being read.
If circumstances require that error/statistical counters be read without the potential for skew, this can
be done by halting the protocol at the tributary. With the protocol halted, the contents of the error /statistical counters in a TSS and in the GSS are frozen at the counts recorded when the protocol
was halted. The counters can then be read without the problem of skew due to read time lags.

4.6 ERROR RECOVERY PROCEDURES
Within a DMV II-based network, there are three basic levels of error recovery involving the user program:
1.

Procedural violations where only the user program is notified.

Recovery from errors requiring protocol shutdown initiated by the user program.

Fatal errors resulting in system shutdown with minimal notice to the user program.

Referring to Table 3-7, procedural error codes from 100 to 140 are reported to the user program with
no recovery required. The remaining two procedural errors (codes 300 and 302) involve error recovery
levels two and three respectively. All network errors require recovery through protocol shutdown, and
the control response (queue overflow) could result in network shutdown.

4-17

4.6.1 Recovery from Network Errors
In all cases, recovery from network errors requires that the protocol be halted at the tributary or station
recording the error. Two similar but separate procedures are recommended for recovery from threshold
errors, and babbling and streaming tributary errors. These recovery procedures are described below.
4.6.1.1 Recovery from Threshold Errors - DMVll threshold errors are detailed in Section 5.3.3. The
recommended recovery procedure to be initiated by the user program at the station recording the errors
is presented below:
1.

Halt the protocol (see Table 3-6).

Read the error counters to determine the nature and cause of the threshold error condition. If
the error results from a shortage of receive buffers, correct the condition. If the transmit or
selection threshold is being exceeded, check the operational condition of the remote station.

When the conditions causing the errors have been eliminated, restart the protocol (see Section 4.3.3).

4.6.1.2 Recovery from Babbling and Streaming Tributary Errors - Babbling or streaming tributary errors are created when their respective timers are exceeded. Therefore, a timeout can result from an
actual error condition, or because the period of the timer is too short for the type of message activity on
the line (see Sections 4.4.2 and 4.4.3). A suggested recovery procedure to be used when encountering
these conditions is:
1.

Halt the protocol.

Check the value of timer parameters and increase if the value is not appropriate.

Restart the protocol (see Section 4.3.3).

If this error condition persists, reconfigure the station as specified by Section 4.3.1.

When the cause of the timeout originates at the remote station, action must be taken at the
remote station to ascertain and correct the fault. The local station is at fault only if the values
of the timer parameters are inappropriate.

4.6.2 Recovery from Procedural Errors
The three procedural errors that require a recovery procedure are:
1.
2.
3.

Nonexistent memory error.
Buffer too small error.
Queue overflow error.

The recovery procedure for each of these errors is detailed in Sections 4.6.2.1 through 4.6.2.3.
4.6.2.1 Recovery from a Nonexistent Memory Error - Nonexistent memory errors occur when the
DMV 11 tries to access an allocated receive or transmit buffer having an invalid bus address. When this
error is detected, the DMVII posts a control response to the user program containing the invalid address (see Section 3.4.2). It is up to the user program to determine whether the nonexistent address
concerns a transmit or receive buffer.
NOTE
Depending on microcode processing circumstances,
the nonexistent memory address returned to the user
program could b~ve been incremented to the next sequential location.

4-18

The suggested recovery procedure for this error is as follows:
1.

Halt the protocol for the tributary or station recording this error to initiate return of all outstanding buffers.

If the error concerns a buffer from the common pool, the user program should issue the global halt command to initiate return of all outstanding receive buffers from the common pool.

Restart the protocol and reallocate buffers as necessary.

Persistent recurrence of this error indicates a possible main CPU or DMVII malfunction.
NOTE
If the network line speed is 56K b/s, the requests for
retransmission generated by a nonexistent memory
address can result in the overflow of the DMVll response queue causing a fatal system error (see Section 4.6.2.3).
4.6.2.2 Recovery from a Receive Buffer Too Small Error - When the DMVII receives a message, it
first checks for the availability of a buffer from the common buffer pool linked list, and if one is available, it uses that buffer. If the common buffer pool is empty or not enabled, the private buffer linked
iist is checked. If a private buffer is not available, the receiving station NAKs the incoming message.
The steps taken by the DMVII microcode in this process are listed below.
1.

Is the message number in sequence? Yes, continue; No, ignore message.

Is the common buffer pool enabled? Yes, continue; No, go to Step 6.

Is the common buffer pool quota = O? Yes, go to Step 6; No, continue.

Is a common pool buffer available? Yes, continue; No, go to Step 6.

Is the common pool buffer too small? Yes, go to Step 8; No, use this buffer.

Is a private buffer available? Yes, continue; No, send NAK - buffer temporarily unavailable.

Is privat~ buffer too small? Yes, send NAK - buffer too small; No, use this buffer.

Is private buffer available? Yes go to Step 7; No, send NAK - buffer too small.
NOTE
The DMVll does not scan the common pool or private linked list structures looking for a buffer of sufficient size. Rather, it uses the next available buffer
from the list.

Buffer too small errors apply only to receive buffers. The procedure for recovery from this error is
dependent on whether the allocated buffer is from the common pool or is a private buffer. The applicable recovery procedures are explained below.
A.

Common pool buffer too small
1.

Assign a private buffer of sufficient size to the receiving tributary through a buffer address/character count command (see Section 3.3.4).

4-19

Both private and common pool buffers too sma'II
1.

Halt the protocol for the offending tributary to initiate return of all outstanding private buffers.

Restart the protocol.

Assign a private buffer of sufficient size to the recelvmg tributary through a buffer address/character count command (see Section 3.3.4).

Private buffer too small, and common pool not enabled
1.

If buffers from the common pool are available to other tributaries, and are of sufficient size,
enable common pool buffers for this tributary (see Section 3.3.4).

If the common buffer pool is not in use for other tributaries, follow recovery procedure B
above.

4.6.2.3 Recovery from a Queue Overflow Error - This error is always fatal to the DMV 11 recording
the error since it forces automatic shutdown of the device. The basic cause of this error is the inavailability of link blocks from the free linked list (see Section 5.4.1.1). Typically, this error results
when the internal response queue overflows because the DMV 11 generated responses faster than the
user program could retrieve responses from the queue. This error can also occur if an inordinate number of receive buffers have been allocated. One cause of response queue overflow is the occurrence of
repetitive nonexistent memory errors in high-speed networks (see Section 4.6.2.1).
When this error occurs, the DMVII posts the most current entry in the response queue to the user
program. The user program then has three seconds after being interrupted to retrieve the response. If it
is retrieved during this three second window, the next response is posted. As long as the user program
retrieves each response within this window, the process continues until the internal response queue is
empty. These responses can then be analyzed to determine the cause of the queue overflow.
After the last response has been posted, or the three second response period has expired, the DMV II
shuts itself down. At this point, returning the DMV II to operational status requires that the start-up
procedure be initiated from the beginning (see Section 4.3).

4.7 BOOTING A REMOTE STATION
DMV II-based networks provide the user program, at the multipoint control station or point-to-point
station, with the ability to boot the main CPU at a remote station that has been shut down due to power
outage or software malfunction. There are three ways this boot function can be performed:
1.

Remote load detect: The control station starts the primary MOP boot procedure for a remote
station.

Power-on boot: The first poll received after power-up at the remote station causes the
DMV 11 at that station to request that the control station start the MOP boot procedure.

Invoke primary MOP: The user program at the remote station causes the DMV 11 to request
that the control station start the primary MOP boot procedure.

4-20

NOTE
Control station is either a multipoint control or
point-to-point station that is transmitting (over the
link) the boot or requested program to the remote
station. Remote station is either a multipoint tributary or point-to-point station that is receiving
(over the link) the boot or requested program.

NOTE
Power-on boot, remote load detect, and invoke
primary MOP are not mutually exclusive. All three
features could be used in a particular application.
Primary MOP boot procedures require that the DMVII be switch-configured in the manner specified
in this section. The steps taking place at the remote station and over the communications line leading to
each of the three primary MOP boot functions are presented in the following sections.
4.7.1 Steps Leading to a Remote Load Detect Boot
The steps taking place at the DMV 11 remote station and its host CPU in response to an enter MOP
mode message from the control station are:
1.

The DMV 11 NPRs a tight-loop routine into main memory.

The DMVll transfers control to the routine through the power fail/restart vector. This routine inactivates the CPU to prevent any intervention during the NPR process.

The DMVl1 then sends a primary MOP request program message to the control station. The
control station responds in turn with a primary MOP memory load with transfer address message containing the boot or related program to be loaded into main memory at the remote
station.

The DMV 11 NPRs that program into main memory, then starts executing the program.

At this point the remote station is operating in the manner intended by the down-line loaded
program.

The steps occurring over the communications line during a remote load detect boot are:
1.

The control station sends an enter MOP mode message to a remote station.

The remote station recognizes the address and password in the message, then inactivates its
host CPU.

The remote station then responds with a primary MOP request program message.

The control station responds to this message with a primary MOP memory load with transfer
address message containing the boot or related program to be loaded into the host CPU at the
remote station.

4.7.2 Steps Leading to a Power-On Boot
When power is restored after a shutdown at a remote station, the DMV 11 performs the same steps used
during a remote load detect boot. However, the first two steps performed over the communications line
are omitted, and the tributary station responds to the first poll from the control station with an MOP
request program message. The same sequence used in the remote load detect boot procedure is then
followed.
4-21

4.7.3 Steps Leading to an Invoke Primary MOP Boot
This boot operation is initiated when a user at a remote station sets the boot and master clear bits in the
DMV 11 initialization register (see Section 3.3.1). The steps taken by the DMV 11 are the same as with
a power-on boot.
4.7.4 DMVll Switch Settings for the Boot Functions
At remote stations, in networks supporting the primary MOP boot functions, the switches must be configured in a specific way in order to properly perform the boot functions (see Section 2.5 and Table 26).
NOTE
The switch setting procedures described below apply
only to tributary stations in a multipoint network
and one node in a point-to-point network.
The unit number (zero or one) of each DMV 11 must be appropriately set. This number allows the boot
program, once it is loaded into the host CPU, to identify the specific DMVll (within the host's floating
address space) performing the boot.
NOTE
When primary MOP booting is supported in a network, the operating mode of each tributary station
eligible for booting must be set in the switches rather
than through the mode definition command.
The operating mode of a DMV 11 is specified by setting the mode enable switch to one (OFF) (switch
number 1 of the boot enable switch pack), and setting switches numbered 6, 7, and 8 to the required
operating mode. The settings for these switches are listed in Table 4-5.
4.7.4.1 Switch Settings for the Power-On Boot Function - To enable the power-on boot function at a
remote station, switch number 4 of the boot enable switch pack (power-on boot) must be set to one
(OFF). In addition, the tributary address of this station must be set in the DDCMP address switch
pack.
4.7.4.2 Switch Settings for the Invoke Primary MOP Boot Function - The DMVl1 switch settings for
the invoke primary MOP boot function are the same as those for the power-on boot function. However,
the setting of the power-on boot switch has no affect on the invoke primary MOP boot.
An additional feature of the invoke primary MOP boot and remote load detect is that it may allow the
tributary address of the remote station to be software assigned instead of switch assigned. This feature is
only valid for remote stations that are multipoint tributaries. To use this feature, the following conditions
must exist.
•

The tributary address/password in the DDCMP address switch pack must be zero.

•

The user program at the remote station must have established the tributary using the control
command (establish tributary). If the remote station is using the multiple address tributary
option. the tributary address used for booting must be the first one established.
NOTE
Invoke primary MOP boot with the software-assigned tributary address does not work if the poweron boot switch is enabled.

4-22

Table 4-5
Mode
Switches

Mode Switch Settings

Line
Characteristics

Network
Configuration

DMC11 Line
Compatibility

Half-duplex

Point-to-point

Yes

OFF ON

Full-duplex

Point-to-point

Yes

OFF ON

Half-duplex

Point-to-point

OFF OFF ON

Full-duplex

Point-to-point

OFF

Half-duplex

Multipoint control
station

N/A

OFF ON

OFF

Full-duplex

Multipoint control
station

N/A

OFF OFF

Half-duplex

Multipoint tributary
station

NjA

OFF OFF OFF

Full-duplex

Multipoint tributary
station

N/A

4.7.4.3 Switch Settings for the Remote Load Detect Boot Function - To enable the remote load detect
boot function at a remote tributary station, switch number 5 of the boot enable switch pack (enable
remote load detect) must be set to one (OFF). For the remote load detect boot function, the switchspecified tributary address also serves as the password which is contained in the enter MOP mode message.

When using boot functions in point-to-point networks, the tributary address/password switches can, for
security purposes, be set to a unique value since the address of a point-to-point node is always known to
be one.

4.8 MAINTENANCE REGISTER EMULATION
The DMV 11 is placed into maintenance mode when the user program sets bits and 6 at the same time
in BSEL I. When this happens, the microcode enters a maintenance loop and sets MNT RDY (bit 7 of
BSEL2) to indicate that the microcode is ready to receive a command as defined by bits zero through
three of BSEL2 (see Figure 4-3). The functions of these commands are described in Table 4-6.
NOTE
The microdiagnostics must complete tests 1-12 as a
minimum before allowing entry into the maintenance
loop.

I n the maintenance mode, the functions of the CSRs are redefined as follows:
•

BSELO, bits zero and four, enable the respective microprocessor LSI bus interrupts as defined
by bits one and two if an internal 6502 interrupt occurs. See Figure 4-3.

4-23

•

BSEL2, bits zero through three, define the maintenance loop command function. Bits four and
five are used for interrupting the CPU on command complete. These interrupts are enabled by
BSELO. Bit seven is set by the microprocessor when the maintenance loop is ready to receive
another command function in bits zero through three (Table 4-6).

•

SEL4 contains a DMV 11 memory location for function codes one through five (Table 4-6).

•

SEL6 contains data written or read for functions one, two, and six. It also contains a 16-bit
address for functions three and four.

•

SELID contains the upper address bits for functions three and four. Only the low byte of this
CSR is used.

NOTE
BSELI0 and 11 are only used in 22-bit mode.
BSEL12 through 17 are not shown because they are
never used by the user /DMVll-command structure.

7
BSEL

RUN

BSEL3

BSEL5
BSEL7

I I

MTRI
CLR

MNT
RDY

. , .
DMVll MEMORY LOCATION (HIGH BYTE)
FOR FUNCTIONS 1-5

"A"
INT

I Jl P I Jl P 1 EN
INTA INTB

"B"
INT

FUNCTION CODE

SEL2

DMVll MEMORY LOCATION (LOW BYTEI
FOR FUNCTlqNS 1-5

BSEL4
SEL4

BSEL6
SEL6

DATA READ OR WRITTEN FOR FUNCTIONS 1, 2 & 6 or 16 BIT ADDRESS FOR FUNCTIONS 3 & 4

.
,

--L

UPPER ADDRESS BITS
FOR FUNCTS 3 & 4

UNUSED

NOT USED

BSEL 11

BSELO

. "A" BSEL2

EN
"B"

MNT
REQ

I
I
NON-MASKABLE INTERRUPT
FLAG REGISTER FROM PIA

*MI
OCCURRED

SEL10
BSEL10

o
MK-2!l17

Figure 4-3

DMVII Maintenance Loop Command Format

4-24

Table 4-6

Maintenance Command Functions BSEL2 Bits 0-3

Octal Code
Bits 0-3

Function

Reserved to avoid unpredictable results.

Read DMVII memory location specified by SEL4 (l6-bit address specifying a
byte). SEL6 contains the data read from this location.

Write DMVII memory location specified by SEL4. SEL6 contains the data
written to this location.

Read 256 bytes of DMV 11 memory. SEL4 points to the starting DMV 11 memory address from which the information is read. The lower eight bits of this address are ignored. SEL6 and BSEL8 point to the starting LSI-II bus address
where the information is stored.

Write 256 bytes of DMVII memory. SEL4 points to the starting DMVII memory address to which the information is written. The lower eight bits of this address are ignored. SEL6 and BSEL8 point to the starting LSI-II bus address
from which the information is read.

Set the 6502 microprocessor's program counter to the value contained in SEL4.
This is used to start the microprocessor executing code at the DMVII memory
location specified by SEL4.

Set internal loop and null clock for functional diagnostics. Null clock is initialized for 56K b/s.

Set maintenance interrupt flags and clear interrupt disable in processor status.

4-25

CHAPTER 5
ASPECTS OF DMVll
MICROCODE OPERATION

5.1 INTRODUCTION
The functionality of the DMVll results from the microprocessor and its associated microprogram or·
microcode. This chapter discusses the microcode as it relates to:
•

The polling algorithm,

•

Error recording, and

•

The internal data base.

5.2 DMVll POLLING ALGORITHM
In a polling operation the tributaries are in effect asked one by one whether they have anything to
transmit. To accomplish this, the control station sends a polling message with a unique tributary address down the line. The station which recognizes the address responds with data messages or a positive
response.
With DMVlls, polling is based on a priority scheme which is derived automatically and applied dynamically by the microcode. To control polling and data message transmission, the DMVII uses the
following information:

•

The tributary's recent poll history,

•

The tributary's user-defined parameters,

•

The tributary's protocol state.

In regard to protocol state, the multipoint network control station polls all established tributaries that
are not in the DDCMP halt state. The protocol state of every established tributary is maintained in the
associated TSS by the control station. When a tributary is eligible for polling, all outstanding transmit
messages for that tributary are sent as the poll, up to the limit imposed by the maximum transmitted
message count. If no transmit messages are available for a tributary eligible for polling, the DMV II
automatically transmits the appropriate DDCMP control message.

The DMVll polling algorithm determines which tributary is to be polled next, based on each tributary's polling urgency level. The DMVII polling algorithm employs the user-defined TSS and GSS polling parameters as the basis for categorizing tributaries into polling levels. The polling algorithm also
determines the rate at which polling urgency is increased within each polling level. A tributary's polling
level is based on its recent response history. This classification mechanism, combined with periodic incrementing of polling urgency, results in the most active tributaries being polled most often.

5-1

5.2.1 Calculating Polling Urgency
The polling urgency (priority) of eo.ch tributary is periodically calculated when a global timer expires.
This periodic calculation enables the algorithm to enforce minimum poll intervals for each tributary,
and to account for competition between tributaries. The minimum poll interval prevents unneeded polls
from:

•
•
•

Delaying other tributaries,
Interfering with output traffic, and
Causing unnecessary processor overhead.

The polling urgency of a tributary is calculated as a linear function of time elapsed since the last poll.
The calculation is truncated when the maximum value of 255 is reached. The three parameters in this
calculation are:
1.
2.
3.

Q - the initial value of the polling urgency (U);
R - the rate at which Q is to be increased;
DELTA T - the polling algorithm global update interval.

Figure 5-1 shows the relationship between these three parameters. The appropriate choice of Q and R
can give a variety of behaviors. For this reason, the choice of these values must be based on the desired
performance. One method of choosing Q and R is to define the minimum poll time and the time to
reach maximum poll urgency, and to use these values in the following equations.
Minimum poll time = 128-Q (DELTA T)
R
Time to reach maximum poll urgency = 255-Q (DELTA T)
R

DEL TAT is the user-defined period of the global timer and its value depends on the line speed. It must
be smaller than the smallest nonzero minimum poll interval, but no smaller than 200 ms. The poll priority is calculated for each tributary and stored in a single byte of the TSS. With every DELTA T, the
polling urgency byte is updated. The following interpretation is placed on its value. These values are
represented as base lines on the graph of Figure 5-1. Figure 5-2 shows the relationship of the polling
urgency to different values of Q and R.

o - 127

Do not poll the tributary. The minimum poll interval has not expired.

128

Minimum poll interval has expired. The tributary is eligible for polling.

129 - 254

Minimum poll interval is exceeded. The tributary is eligible for polling. The
higher values indicate increasing priority in the event of competition between
tributaries.

255

Maximum poll urgency is reached. Competition between tributaries at this priority is round-robin.

This method of determining values for Q and R is applicable when static behavior is desired. For many
applications, however, dynamic behavior can improve performance by polling active tributaries at a
faster rate and with a higher priority than inactive tributaries.
During each DELTA T time period, the control station polling algorithm updates the urgency of each
operational tributary by adding the value of R for the appropriate polling state (excluding dead) to the
urgency value of each tributary. This updating sequence is performed on the TSS data base in the order

5-2

in which tributaries were originally established at the control station. When the polling algorithm determines that the next poll is to be sent, it selects the tributary to be polled by scanning the TSS data base
(in the original order of tributary establishment), starting at the TSS following the last tributary polled.
In this process, the tributary having the highest value of U from active, inactive, and unresponsive
tributaries is selected as the next tributary to be polled.
TIME TO
MAXIMUM URGENCY

------------------------- ---7
1
~-----------------------------~-----------------------------~,

255

ELIGIBLE FOR
POLLING

s>u

MINIMUM
POLLING INTERVAL

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

~:::::> 128
I ========= === = == = -= __
127
<-'

==_-___-_-=--= ==== ==-=-_-=--:..-=

NOT POLLED

::J
-'

a..

6. t = 200ms
MK-2643

Figure 5-1

Interrelationship Between Polling Parameters Q, R, and DELTA T

If an urgency of 255 is detected during the process of scanning the TSS data base for the tributary
having the highest value of U, the scan process is halted and that tributary is immediately selected for
polling. Once the selected tributary is polled, its urgency reverts to the assigned value of Q for its polling level.

Dead tributaries are polled at a rate determined by the user-defined parameter DEAD T. One dead
tributary is polled at each expiration of the DEAD T timer, and the scan of dead tributaries is resumed
from the last dead tributary polled.

5-3

255

127r-----------~~----------_+------------_r-------------------------------

e"
Z
~

...J

oQ.

2.0

3.2

4.0

6.375
DELTA

Figure 5-2

8.0
T

9.55
200ms

12.0

16.0
MK-2647

Relationship Between Polling Parameters Q, R, and the Minimum Polling Interval

The dynamic polling algorithm uses Q and R values based on dynamically modified states. There are
four of these states:
1.

Active - The polling algorithm maintairis a tributary as active when it responds to polls with
data messages.

Inactive - The polling state of an active tributary is changed to inactive when it responds to a
consecutive number of polls with nondata DDCMP messages. The count of consecutive nondata messages received from a tributary in the active state is designated by the user-defined
parameter NDM-INACT (number of no-data messages required to go inactive).

Unresponsive - A tributary currently active or inactive is changed to the unresponsive state
when it fails to respond in any way to a consecutive number of polls (each poll results in a
selection timeout). The count of consecutive polls without responses is designated by the
user-defined parameter TO-UNRESP (number of timeouts to go unresponsive).

Dead - A cUfiently unresponsive tributary which continues to be unresponsive to consecutive
polls is changed to dead. This occurs when the number of selection interval timeouts designated by the user-defined parameter TO-DEAD (number of timeouts to go dead) is exceeded. Unlike tributaries in the other polling states, dead tributaries are always polled on a
iound-iobin basis ..vith the period between polls being determined by the user-defined global
parameter DEAD T (dead timer).

5-4

When specifying the parameters controlling polling levels, the user has the option of accepting the
defaults (see Table 4-2 and 4-3), or selecting specific values in place of these defaults. The user program can set the polling state of a tributary to any state at any time by issuing a latch polling state
control command. The polling state imposed by a control command remains in effect, irrespective of
tributary performance, until polling control is handed back to the polling algorithm by the user program. This is done by issuing an unlatch polling state control command.
Figure 5-3 shows the relationship of the the default values of Q and R for the active, inactive, and
unresponsive polling states.
255r------------,~----------------------------------------------__- - - - - - -

ACTIVE Q=255,

R=O

ELIGIBLE FOR
POLLING

5
>="

zw
(!)

~ 128
(!)

:::i

...J

a..

NOT POLLED

O~--~----~--_r----~--_r----+_--_r----r_--_r----~--~----~~_r----~

200ms

1.2sec

2.60sec

DELTA T =200ms
MK-2642

Figure 5-3

Relationship Between the Default Values for Q and R for the Three
Polling Activity Levels

5-5

Each tributary has Q and R values defined by the user for the active, inactive, and unresponsive polling
states. This allows dynamic modification of the behavior of the polling algorithm. The basic mechanics
of the polling algorithm are:

•

If a tributary always responds to a poll with data. it remains in the active state. The polling
urgency in this case is calculated using the Q and R values specified for the active state.

•

If a tributary responds to a user-defined number of consecutive polls with no data messages
(ACKs only), polling is changed to inactive. The polling urgency is then calculated based on
the Q and R values defined for the inactive state.

•

If a tributary in either the active or inactive states fails to respond (times out) to a predetermined number of consecutive polls, the polling state is changed to unresponsive. The Q
and R values defined for the unresponsive state are used to calculate the polling urgency.

•

If a tributary in the unresponsive state fails to respond to a predetermined number of consecutive polls, the polling state is changed to dead. The user is notified of this transition by a
control response. Polling dead tributaries is very time-consuming because it usually requires
a timeout. Therefore, dead tributaries are not polled on a priority basis. Instead, a global poll
interval is defined for dead tributaries. Each time this timer expires, a single dead tributary
is polled. If at any time a dead tributary responds to a poll with a data message or ACK, its
state is changed to active.

NOTE
A tributary (not in the active polling state) is automatically returned to the active state when it responds to a poll with a valid data meSsage. It also
becomes active when the user program allocates a
transmit buffer to it.

Figure 5-4 is a state diagram describing the transitions between polling states. The actual transitions are
dependent on the particular polling parameters.
The user may control sending of all polls by defining a poll delay interval that must expire before a poll
can be sent.
The program-selectable parameters which pertain to polling are included in Table 4-2. These parameters are set by the user with a write TSS command.
5.2.2

Criteria for Determining Polling Parameters

Although there are no absolute rules for determining polling parameters, there are general guidelines
for deriving them. These guidelines are presented in sections 5.2.2.1 through 5.2.2.4.
Determining a Value for DELTA T - For most multipoint network applications, the default
value of 200 ms for DELTA T is adequate. The default value of 200 ms is the smallest permissible
value for DELTA T and represents the actual time required for the microcode to update the urgencies
of 12 tributaries. However, in specific cases a higher value of DELTA T might be recommended. An
example of this is a network formed by low traffic devices.
5.2.2.1

5-6

NOTE
The minimum polling interval defines the time required for a tributary to reach the urgency threshold
value of 128. This is the minimum time required to
be eligible for polling. The maximum polling interval
cannot be determined. This is because it is a function
of line speed, message traffic, the number of tributaries in a network, and the polling states of those
tributaries. These variables make it impossible to
predict the time at which any tributary in a network
is polled.

MK·' 956

Figure 5-4

State Diagram of Polling State Transitions

5.2.2.2 Determining Values for Q and R - For a given value of DELTA T, the minimum polling interval is a function of the user-defined parameters Q and R. For example, if a minimum polling interval of
3.2 seconds is desired for a tributary (assuming DELTA T = 200 ms), the parameters Q = 0, and R =
8 satisfy this requirement. With these values of Q and R, the time to reach maximum polling urgency is

5-7

6.375 seconds (see Figure 5-2). Notice that if Q = 64 and R = 4, the minimum polling interval remains at 3.2 seconds but the maximum polling urgency increases to 9.55 seconds.
NOTE
Reaching maximum poiling urgency represents maximum eligibility for polling, but does not guarantee
that a tributary will be polled.
Figure 5-3 graphs the relationship between the default values of Q and R for each of the three polling
states. When all tributaries in a network have the default value for Q and R, and all tributaries are in
the active polling state, the manner of polling is round-robin.
5.2.2.3 Determining a Value for Poll Delay - The user-defined global parameter poll delay imposes a
fixed delay between control station polls. This provides a mechanism for regulating message traffic
without changing the values of Q and R for individual tributaries. During this delay, transmission from
the control station to tributaries is halted for the interval defined by the poll delay timer. This interval
begins when the tributary just polled deselects itself.
The ability to regulate message traffic through a single parameter is valuable in multipoint networks.
This is especially true where DMVlls are configured together with slower character interrupt communication devices such as DUPlls. The value selected for poll delay in these circumstances is a function
of the character handling rates of the non-DMVII devices.
In remote multipoint networks where the distance between the control station and tributaries varies
significantly, there is a greater chance of transmit and receive errors. This is due to the difference in
communication line settling time in such a network. In such instances, the settling time for the most
distant tributary station should be used for determining a value for poll delay.
For DMV II-implemented high-speed local networks, this parameter is unnecessary. The default value
(zero) for poll delay is used in these networks.
5.2.2.4 Determining a Value for DEAD T - This global parameter establishes the rate at which dead
tributaries are polled. Dead tributaries are polled on a round-robin basis, with one tributary polled at
each expiration of the dead tributary timer.
Polling dead tributaries can significantly impact network line utilization. The shorter the period of this
timer - the greater the impact. For a given value of DEAD T, the impact decreases as system line
speed increases. When determining a value for this parameter, the primary goal is to minimize the impact on network line utilization.
The value for DEAD T should be based on the period of the selection interval timer for the specific
application. For example, if the period of the dead tributary timer and the selection interval timer are
equal, only dead tributaries are polled. For most system applications, the period of the dead tributary
should be from three to ten times greater than that of the selection interval timer. This of course depends on line speed. The default value for DEAD T is ten seconds. This is about three times the default
value for the selection interval timer.
5.3 ERROR COUNTERS
In multipoint networks many tributaries tie to the same transmission line. Because of this, it is more
difficult to determine which link, if any, is causing errors. To aid in troubleshooting, the DMVll maintains extensive error counters. Every DMVII in the network (the control station and each tributary)
uses error counters to record errors. This allows user programs at any DMVII in the network to determine overall error rates and to detect a malfunctioning link.

5-8

Data link errors are indicated to the DMVII by DDCMP negative acknowledge messages (NAKs).
Each NAK contains an address field and a reason code that identifies the source and reason for the
NAK. In general, when an error is detected in an incoming message, the station that receives the message sends a NAK to the station that sent the message. By recording NAKs sent and NAKs received,
each point or tributary in the network is able to compile statistics on the condition of the link established between the two stations. DDCMP error recording has been designed so that even if one of the
stations on the link cannot record errors, the other station may be used to record errors for all communications in both directions on the link.
There are three main categories of error counters used by the DMV 11; data link counters, station
counters, and threshold counters. Data link counters and threshold counters are maintained for each
tributary /contiol station pair on a physicallink. These counters are iocated in the tributary status slots
of the data memory (Figure 5-5). Station counters are maintained for the physical link as a whole, and
are located in the global status slots of the data memory (Figure 5-6). Unless otherwise stated, all
counters increment to a maximum value and hold that value until cleared.

5.3.1 Data Link Error Counters
Data link counters are of two types; cumulative and background. The cumulative counters are 8-bit
registers which latch at 255. The background counters are 16-bit registers which latch at 65535. The
cumulative data link counters record and total all occurrences of an error and group them into the following categories.

•
•
•
•
•
•
•

Data errors outbound,
Data errors inbound,
Local reply timeouts,
Remote reply timeouts,
Local buffer errors,
Remote buffer errors,
Selection timeouts.

Background data link counters are used to provide a statistical base for the cumulative error counters
and therefore record:
•
•
•

The number of data messages transmitted,
The number of data messages received, and
The number of selection intervals.

A point-to-point station maintains a single set of data link counters. Multipoint stations (control and
tributary) maintain a separate set of data link counters for each established tributary. Data link
counters are cleared by:
•
•
•

A master clear of the D MV I I,
A control command to establish the tributary, or
A user-issued control command to read and clear the TSS error counters.

5.3.1.1 Data Errors Outbound - This 8-bit group counter records NAKs received for data errors occurring on the communications channel outbound from this station. There are three types of outbound
errors for which this counter records NAKs received; header blockcheck (OHBCC), data field blockcheck (ODBCC), and reply response (OREP). Three separate flag bits indicate which type of outbound
error is being counted.
•

OHBCC (outbound header blockcheck) is set when a NAK with a reason code of one is received for a header block-check error for either data or control messages.

5-9

•

ODBCC (outbound data field blockcheck) is set when a NAK with a reason corle of two is
received for a data field block-check error.

•

OREP (outbound reply response) is set when a NAK with a reason code of three is received
for a reply message response.
TRIBUTARY STATUS SLOT (TSS)
ADDRESS (OCTAL)

RESERVED
RECEIVE THRESHOLD ERRORS

TRANSMIT THRESHOLD ERRORS
SELECTION THRESHOLD ERRORS

DATA MESSAGES TRANSMITIED

DATA MESSAGES RECEIVED

SELECTION INTERVALS

DATA ERRORS OUTBOUND
RESERVED

I I
OREP

ODBCC

OHBCC

DATA ERRORS INBOUND
RESERVED

IIREP IIDBCC IIHBCC

LOCAL BUFFER ERRORS
RESERVED

LBTS

LBTU

REMOTE BUFFER ERRORS
RESERVED

I RBTS I RBTU

SELECTION TIMEOUTS
RESERVED

IRTS

NRTS

LOCAL REPLY TIMEOUTS
REMOTE REPLY TIMEOUTS

MK-1960

Figure 5-5

Data Link and Threshold Error Counters

5-10

GLOBAL STATUS SLOT (GSS)
ADDRESS (OCTAL)

REMOTE STATION ERRORS

I
16

RSEL

LUNDR

RMHFE

ROVRN

LOCAL STATION ERRORS

I
17

RSTR

LOVR

LMHFE

LOVRN

GLOBAL HEADER BLOCK CHECK ERRORS
MAINT. DATA BLOCK CHECK ERRORS

MK·1959

Figure 5-6

Station Error Counters

5.3.1.2 Data Errors Inbound - This 8-bit group counter records occurrences which normally result
from data errors on the communications channel inbound to this station. Three separate bits indicate
specific error types associated with this counter.
•

IHBCC (inbound header blockcheck) is set when messages having header-block check errors
are received. When this error occurs, point-to-point stations and multipoint control stations
send a NAK with a reason code of one. A multipoint control station records this error for the
selected tributary regardless of the address field in the received message. A multipoint tributary records this error only if the address field matches its station address.

•

IDBCC (inbound data field blockcheck) is set when NAKs with a reason code of two are to
be sent for data field block-check errors.

•

IREP (inbound reply response) is set when NAKs with a reason code of three are to be sent
for a reply response.

5.3.1.3

Local Reply Timeouts - This 8-bit counter records occurrences which result from:

•

The loss of communications between two stations while the one recording this error has data
to transmit, or

•

The choice of an inappropriate value for the reply timer.

Specifically, this error counter records the sending of a REP message.
5.3.1.4

Remote Reply Timeouts - This 8-bit counter records occurrences which result from:

•

The loss of communications between two stations while the remote station has data to transmit, or

•

The choice of an inappropriate value for the remote station reply timer.

Specifically, this counter records ACKs sent in response to a REP. The remote station sent a REP
because it received no acknowledgement for messages it previously sent. The local station received
those messages, but the remote station never received the acknowledgement.

5-11

5.3.1.5 Local Buffer Errors - This 8-bit counter records the fact that the user program at the station
recording the error failed to properly allocate receive buffers to data messages from the remote station.
Two separate bits indicate the specific errors associated with this counter.
•

LBTU (local buffer temporarily unavailable) is set when a buffer is temporarily unavailable.
This condition indicates that a NAK with a reason code of eight is to be sent.

•

LBTS (local buffer too small) is set when a local buffer is too small for the incoming message. This condition indicates that a NAK with a reason code of 16 is to be sent.

5.3.1.6 Remote Buffer Errors - This 8-bit counter records the fact that the user program at the remote
station failed to properly allocate receive buffers to data messages from the station recording the error.
Two separate bits indicate the specific errors associated with this counter.
•

RBTU (remote receive buffer temporarily unavailable) is set when a NAK with a reason
code of eight is received.

•

RBTS (remote receive buffer too small) is set when a NAK with a reason code of 16 is received.

5.3.1.7 Selection Timeouts - This 8-bit counter records the occurrences which result from:
•
•
•

Loss of communications with a remote station,
Data errors on the communications channel to or from the remote station, and
The choice of an inappropriate value for this station's select timer.

This counter is used only by half-duplex point-to-point or multipoint control stations. Two separate bits
indicate the specific errors associated with this counter.
•

NRTS (no reply to select) is used to record selection intervals in which no transmission is
received from the tributary, and no attempt to transmit is detected. Specifically, it records
the expiration of the select timer without the receipt of a valid control message or header, or
the detection of an attempted transmission.

•

IRTS (incomp'ete reply to select) is used to record selection intervals which were not properly terminated. Specifically, it records the expiration of the select timer preceded by receipt
of a valid control message, receipt of a valid header, or detection of an attempted transmission. An attempted transmission is indicated by:
The presence of a carrier signal,
The receipt of a OOCMP synchronization sequence, and
The receipt of an SOH, ENQ, or OLE.

5.3.1.8 Data Messages Transmitted - This 16-bit counter records messages transmitted by this station,
and latches at a count of 65535. It can be used as a statistical base when evaluating data errors outbound, local reply timeouts, and remote buffer errors. Messages sent as a result of retransmission are
not included in this count.
5.3.1.9

Data l\tlessages Received - This 16-bit counter records messages received by this station, and
latches at a count of 65535. It can be used as a statistical base when evaluating data errors inbound,
remote reply timeouts, and local buffer errors. Messages received out of sequence or in error are not
included in this count.
5-12

5.3.1.10 Selection Intervals - This 16-bit counter records the number of times this station selects the
other station. It also latches at a count of 65535. Specifically, it records the number of messages transmitted with the select flag on. It is only used by half-duplex point-to-point and multipoint control stations. It can be used as a statistical base when evaluating the number of selection timeouts.
5.3.2 Station Error Counters
Station counters are 8-bit counters which latch at 255 and record unusual occurrences. These occurrences may be the result of:
•

A hardware or software fault at this station,

•

A hardware or software fault at a remote station, or

•

A data error on the communications channels undetected by the header block-check field.

A single set of these counters is used for all tributaries on a multipoint link.
There are four types of station counters:
1.
2.
3.
4.

Remote station errors,
Local station errors,
Global header block-check errors, and
Maintenance data field block-check errors.

Station counters are cleared by:
•
•

A master clear of the D MY 11, or
A user-issued control command to read and clear the GSS error counters.

5.3.2.1 Remote Station Errors - This 8-bit counter records occurrences caused by a fault in a remote
station or by an undetected data error on the channel inbound to this station. Four separate bits indicate
the specific errors associated with this error counter.
•

ROYRN (remote receive overrun) is set when a NAK with a reason code of nine is received
for a receive overrun.

•

RMHFE (remote message header format errors) is set when a message is received which has
a header format error. This condition indicates that a N AK with a reason code of 17 is to be
sent.

•

RSEL (remote selection address error) is set when a multipoint control station receives a
message containing an address field which does not match the address of the currently selected tributary. RSEL is a flag used only by multipoint control stations.

•

RSTR (remote streaming tributaries) is set by either one of two events: 1) an implementation-dependent maximum transmission interval is exceeded without releasing the channel
(babbling tributary), or 2) the channel is not released following the end of a selection interval
(streaming tributary).

5.3.2.2

Local Station Errors - This 8-bit counter records occurrences caused by a fault in a local station or by an undetected data error on the channel outbound from this station. Four separate bits indicate the specific errors associated with this error counter.
•

LOYRN (local receive overrun, NAK sent) is set for local station receive overruns. This condition indicates a NAK with a reason code of nine is to be sent.

5-13

•

LOVR (local receive overrun, NAK not sent) is set by a receive overrun when a NAK is not
sent. For a multipoint tributary, this happens if an overrun occurs while receiving a header.
For other stations, this occurs when the station is not in the DDCMP run state.

•

LUNDR (local transmit underruns) is set when a transmit underrun occurs.

•

LMHFE (local message header format error) is set when a NAK with a reason code of 17 is
received to indicate a message with a header format error was sent by this station.

5.3.2.3

Global Header Block-Check Errors - This 8-bit counter records the occurrence of header
block-check errors that are not recorded on a per tributary basis. Specifically, it counts header blockcheck errors for maintenance messages and for messages to tributaries where the address field does not
match the station address.

5.3.2.4 Maintenance Data Field Block-Check Errors - This 8-bit counter records the occurrence of
data field block-check errors for maintenance messages.
5.3.3 Threshold Error Counters
Threshold error counters are used to determine if a persistent fault exists. A persistent fault is one
which occurs seven consecutive times. Whenever a threshold counter reaches its maximum value (7),
the user program is notified by a control response.
In the DDCMP run state, threshold counters are cleared when the user is notified. In this way the user
is continually informed of a persistent fault. In the DDCMP ISTRT and ASTRT states, threshold
counters are not cleared when the user is notified. In this way the user is not continually informed of an
inoperative remote station.
A point-to-point station maintains a single set of threshold counters. A multipoint control station maintains a separate set for each tributary. A multipoint tributary maintains a single set unless it supports
multiple tributary addresses in which case it maintains a single set for each established tributary address.
There are three types of threshold error counters: transmit, receive, and selection.

5.3.3. t

Transmit Threshold Errors - This 3-bit counter is incremented (if less than seven) in the following instances.
1.

The DMV 11 is in the ISTRT state when a STRT message is sent,

The DMVII is in the ASTRT state when a STACK message is sent, or

The DMV11 is in the run state and a NAK with a reason code other than three (REP response) is received, or when sending a REP message.

The transmit threshold error counter is cleared:
•

Upon entering the ISTRT, ASTRT, or run states.

•

While in the run state one of the following occurs:
A transmit threshold error is reported,
A NAK, ACK, or data message is received acknowledging a new message, or
A NAK, ACK, or data message is received when no messages are outstanding.

5-14

5.3.3.2 Receive Threshold Errors - This 3-bit counter is incremented (if less than seven) when a NAK
with one of the following reason codes is sent.
Reason Code

Description

Header block-check error.
Data field block-check error.
REP response.
Buffer temporarily unavailable.
Receive overrun.
Message header format error.

2
3
8
9
16

This counter is cleared when:
•

Entering the ISTRT, ASTRT, or run states,

•

A control message with a correct header blockcheck is received without a header format error,

•

A data message with correct header and data field blockchecks is received without a header
format error, or

•

In the run state, a receive threshold error is reported.

5.3.3.3 Selection Threshold Errors - This 3-bit counter is only used by multipoint control stations and
half-duplex point-to-point stations. It is incremented (if less than seven) when a selection timeout occurs.
It is cleared upon receipt of a message with the select bit set, or while in the run state and a selection
threshold error is reported.

5.4 DMV11 MICROCODE INTERNAL DATA BASE OVERVIEW
Functionally, the DMV II internal data base provides the mechanism for managing:
•

The assignment and completion of transmit and receive buffers,

•

The queuing of DMVII responses,

•

The assignment of TSS structures to established tributaries for the storage and maintenance
of tributary and global status information.

A map of this data base is shown in Figure 5-7. The data base is implemented by three basic structures:
•
•
•

Linked lists,
Slot mapping table,
TSS and GSS structures.

Each of these are described below in terms of organization and function.

5.4.1 Linked Lists
A linked list is an open-ended data list made up of fixed-length blocks linked by pointers. Each of these
blocks (link blocks), contain seven bytes of data and a one byte pointer to the next link block in the list.
The pointer in the last block in the list is a terminator value. Figures 5-8 and 5-9 illustrate the standard
format for DMVll linked-list structures.

5-15

HEXADECIMAL

0000
SCRATCH PADS

16 BYTES

Q-BUS CSRs

8 BYTES

SCRATCH PADS

32 BYTES

OUT NPR ADDRESS

3 BYTES

SCRATCH PAD

1 BYTE

IN NPR ADDRESS

3 BYTES

SCRATCH PAD

BYTE

GLOBAL STATUS SLOT

64 BYTES

SLOT MAPPING TABLE (SMT)

256 BYTES

MICROPROCESSOR STACK

64 BYTES

10
1B

3B
3B

3C
3F

80
CO

1 FF

500

8UFFER AND OUTPUT QUEUE

98 ENTRIES

8 BYTES/ENTRY

TRIBUTARY STATUS SLOTS
12 ENTRIES

64 BYTES/ENTRY

800
MK·2495

Figure 5-7

Data Memory Map

A DMV 11 linked list is made up of five kinds of linked lists.
1.

The free linked list - A list of empty link blocks used by the microcode to form the remaining
kinds of linked lists.

The response linked list - A queue of responses for posting to the user program.

The common buffer pool linked list - A list of the accessing information for each receive
buffer assigned to the common pool. There is one link block for each assigned buffer.

Receive buffer linked list - A list of receive buffer accessing information. One of these is
maintained by the microcode for each established tributary having private receive buffers
assigned. There is one link block for each buffer.

Transmit buffer linked list - A list of transmit buffer accessing information. One of these is
maintained by the microcode for each established tributary having transmit buffers assigned.
There is one linked list for each buffer.

5.4.1.1 The Free Linked List - The free linked list from which all other linked lists draw link blocks, is
maintained in the lower section of data memory called the buffer and output queue (BOQ) (Figure 57). These 832 bytes translate into a total of 104 link blocks available for use by the operational linked
lists. In this way, the free linked list functions as a finite resource for the operational linked lists.

5-16

LINK BLOCK
POINTER A

START OF LIST
POINTER

DATA

I LINK BLOCK I
POINTER B

DATA

• LINK BLOCK i
POINTER C

DATA

.E
.F

377

TERMINATOR

DATA

MK-1981

Figure 5-8

DMVll Linked List Structure Format

As previously stated, a linked list is equipped with two list pointers; one that points to the start of the
list and one that points to the end of the list. When a link block is removed from the free linked list, the
start of the list pointer is changed to point to the next available link block in the free linked list. When a
link block is completed by one of the operational linked lists, it is added to the end of the free linked list
and its internal pointer is set to the terminator value of 377 octal. In addition, the internal pointer in the
next to last link block is changed from 377 octal to the address of the link block just added. The startand end-of-list pointers for the free linked list are maintained in the station GSS.

5-17

Link blocks are removed from the free linked list and added to the receive, transmit, or common pool
buffer linked lists when the user program issues control or buffer address/character count commands
for that purpose. Similarly, link blocks are removed from the free linked list and added to the response
linked list when the DMVll microcode posts a response to the user program. If the last link block is
removed from the free'linked list, the start of the list pointer is set to the terminator value of 377 octal
to indicate there are no more link blocks available. In this event, the next request for a link block generates the fatal error QUEUE OVERFLOW. For this reason, the buffer allocation strategy for a user
program must be designed to assure an adequate number of link blocks.

LINK POINTER
MESSAGE NUMBER

POINTER TO THE NEXT LINK BLOCK
DDCMP MESSAGE NUMBER

BSEL 3

TRIBUTARY ADDRESS

BSEL 4

BUS ADDRESS

BSEL 5

BUS ADDRESS

BSEL 6

CHARACTER COUNT LOW

BSEL 7

CHARACTER CNT HIGH, BA16, BA 17

BSEL 2

TYPE CODE AND BA 18·21

MK·2497

Figure 5-9

Standard Link Block

5.4.1.2 The Response Linked List - This linked list functions as a queue of buffer disposition, control,
and information responses to be posted to the user program. The format of the link block for each of
these three responses is shown in Figure 5-8. When preparing a link to convey a control or information
response, the microcode clears all unused bit positions in the link block to zero. However, link blocks
restored to the free linked list remain unchanged.

The start-of-list and end-of-list pointers for the response linked list are maintained in the station ass.
5.4.1.3

Buffer Linked Lists - A buffer linked list is provided for each type of message buffer allocated

by a user program. These are:
•
•
•

Common pool receive buffers,
Private receive buffers, and
Transmit buffers.

Each link block in a buffer linked list provides the location and size of a buffer in main memory.
The Common Buffer Pool Linked List - This linked list provides a queue of receive buffers available to

all established tributaries according to the quota assigned to each tributary.
Common pool buffers are assigned through the buffer address/character count command, and enabled
with tributary quota assignments through the control command (see Section 3.3.3). The start-of-list and
end-of-list pointers for this linked list are maintained in the station ass.
Receive Buffer Linked List - This linked list serves as a queue of private receive buffers. One list is

maintained for each tributary established at a multipoint station. For point-to-point stations, one list is
maintained at each station. The start- and end-of-list pointers for each receive buffer linked list are
maintained in the associated tributary's (or station;s) TSS.
5-18

Transmit Buffer Linked List - This list functions as a queue of transmit buffers. One list is maintained
for each tributary established at a multipoint station. For point-to-point stations, one list is maintained
at each station. The start- and end-of-list pointers for each transmit buffer linked list are maintained in
the associated tributary's (or station's) TSS.
A unique feature of this link block is the message number field. When a message is transmitted from a
buffer, the header of that message contains the DDCMP message number (in the message number
field). The microcode uses this field to locate the buffer for a message that has been NAKed after
transmission and, therefore, must be retransmitted.
5.4.2 Slot Mapping Table
Under DDCMP, the 8-bit message header address fieid permits a maximum of 255 unique tributary
addresses in a multipoint network. However, the DMVII microcode limits the number of established
tributaries to 12. In order to implement DDCMP, a tributary in a DMV II-based multipoint network
can have a TSS address in the range of 1 to 255. However, only 12 of these tributaries may be established at anyone time.
TSS addresses are assigned at both control and tributary stations through the slot mapping table
(SMT). As shown in Figure 5-7, this table occupies 256 locations in DMVII data memory; one location
for each of the 255 possible tributary addresses, and one location to address the ass.
The function of the SMT is to map an 8-bit tributary address into one of the 12 available TSS structures. When a tributary is deleted, its TSS and SMT entry is released for reassignment. When 12 tributaries are established and an attempt is made to establish a 13th, a procedural error is posted to the user
program.
5.4.3 TSS and GSS Structures
The TSS and ass structures occupy separate sections of data memory. The ass is a single 64-byte
section while the TSS structure consists of twelve 64-byte sections.
5.4.3.1

The Global Status Slot (GSS) - Functionally, the ass is used to:

•

Maintain control and status information specific to the operation of the microcode,

•

Record event counts and error conditions that are global in nature, and

•

Store global parameters.

The majority of the ass is devoted to microcode control and status information. A detailed map of the
ass is shown in Figure 5-10.
Access to the ass is accomplished on word boundaries. A user program can read any ass location
through the control command. The content of the addressed location is transferred to the user program
through an information response. A user program can read and clear only ass station error counters.
The four global parameters (locations 34 through 37) are written by the user program through the control command.
5.4.3.2 Tributary Status Slots (TSS) - A TSS contains four general categories of tributary information (Figure 5-11):
1.
2.
3.
4:

Protocol and tributary status,
Error and statistical counters,
Message exchange variables, and
Polling parameters.

5-19

Protocol and Tributary Status - This category includes information on the tributary's protocol state, its
status with relation to the logical communications line, its protocol status, and its polling status. Tributary polling status is maintained only at a multipoint network control station. Although this information is only pertinent to, and used by the DMVII microcode, it can be read by a user program.
Error and Statistical Counters - These counters provide the user program with a wide range of error
counts, and a set of statistical counts that permit analysis of the meaning of specific error counts. These
counters can be read and cleared by the user program. The function of each of these counters is described in detail in Section 5.3.
Message Exchange Variables - This category includes a range of variables used by the microcode to
control the transmission and reception of message data. This includes the common buffer pool quota
assigned by the user program.
A group of timers is also included in the message exchange variables. These timers can be preset to a
specific timeout value by the user program, and directly concern message traffic transferred on the
logical link by the associated tributary. These timers are referred to as:
•
•
•
•

Transmit delay timer,
Selection interval timer, *
Maximum transmitted message count,
Babbling tributary timer.

The link management functions performed by these timers is detailed in Chapter 4.
Polling Parameters - These parameters are user-defined values that are used by the polling algorithm
to conduct dynamic polling activity in multipoint networks. The functions performed by the DMVII
polling algorithm, and the criteria for determining the values for each parameter, are discussed in detail
in Section 5.2.

* A i.imeout vaiut: [VI the selectiun intcn:al timer is maintained in each tributary's TSS, but the actual timer is ml'lintl'lined in
the GSS.

5-20

GSS
ADDRESS

POLPTR
RCVPTR

RPM CNTR

XMTPTR

TSP

NASP
BUFPTR

S/OF

sioa

SIOC

(HIGH)

MODEM

UNUSED

CLEAR TO SEND TIMER (LOW)

REMOTE STATION ERRORS

I RSTR I RSEL IRMHFEI ROVRN
16

TIMER STATUS

LOCAL STATION ERRORS

I LOVR ILUNDR\ LMHFE ILOVRN

SIR TIMER (LOW)
7

ACKTIM

(HIGH)

E/OC

(LOW)

FLAG REGISTER "D"

EIoa
5

ACKTIM

MODE

E/OF

(HIGH)

BICW TIMER (LOW)

GLOBAL HDR BCC ERRORS
MAINT DATA BCC ERRORS
MK-2489

Figure 5-10

Global Status Slot (Sheet 1 of 2)

5-21

GSS
ADDRESS

GSS
ADDRESS
XHDR
-. --

(1)

POLL DELAY TIMER (LOW)

(2)

(HIGH)

(3)
(4)

DEAD SCAN

(5)
(6)

RCVHDR (1)

NUMBER OF SYNCS
RESERVED

(3)

(4)

CARRIER LOSS TIMER
USYRT HANG TIMER

(2)

POLL UPDATE POINTER

CARRIER WAIT
TIMER COUNTER

(5)

DELTA T

(HIGH)

(6)

R TIMER (LOW)

DEAD T

(LOW)
(HIGH)

(HIGH)

(LOW)

D TIMER (LOW)

POLL DELAY

(HIGH)

(LOW)
(HIGH)
MK·2490

Figure 5-10

Global Status Slot (Sheet 2 of 2)

5-22

TSS
ADDRESS

TRIB STATUS FLAGS
TRIB STATUS FLAGS

POLL RATE (Ri)

RESERVED

COMMON POOL QUOTA

RECEIVE THRESHOLD ERRORS

TRANSMIT THRESHOLD ERRORS
SELECTION THRESHOLD ERRORS

DATA

TRANSMITTED

IREP I

!DBCC I

IHBCC

LBTS

LBTU

BEMOTE BUFFER ERRORS

RBTS I

RBTU

SELECTION TIMEOUTS
RESERVED

MESSAGES

OHBCC

LOCAL BUFFER ERRORS

RESERVED

ODBCC I

DATA ERRORS INBOUND

RESERVED

MAX MSG COUNTER

OREP I

RESERVED I

POLL PRIORITY (Vi)

DATA ERRORS OUTBOUND
RESERVED I

POLL STATUS FLAGS

SELECTION
INTERVALS

TRIBUTARY ADDRESS
POLL STATUS FLAGS

MESSAGES

RECEIVED

NAK REASON

DATA

IRTS I

NRTS

LOCAL REPLY TIMEOUTS
REMOTE REPLY TIMEOUTS
MK-2722

Figure 5-11

Tributary Status Slot (Sheet 1 of 2)

5-23

TSS
ADDRESS

N HIGHEST MSG NUMBER XMITD

A HIGHEST MSG NUMBER ACK'D

T NEXT MSG NUMBER TO XMIT

X LAST MSG NUMBER XMITT

CX (CONTROL X REPLY T/O)

E/OX END OF XMIT BUFFER QUEUE

S/OR START OF RCV BUFFER QUEUE

TRANSMIT

DELAY

-->

INACTIVE STATE

#T/O

--->

UMRSP

#T/O

--->

DEAD STATE

SELECTION INTERVAL
TIMING COUNTER

TIMER

#NDM

MAXIMUM MESSAGE COUNTER

E/OR END OF RCV BUFFER QUEUE

Q VALUE FOR UMRSP
R VALUE FOR UMRSP

R HIGHEST MSG NUMBER RCV'D

Q VALUE FOR INACTIVE STATE
R VALUE FOR INACTIVE STATE

S/DX START OF XMIT BUF QUEUE

Q VALUE FOR ACTIVE STATE
R VALUE FOR ACTIVE STATE

XPTR ADDR OF LNKBK FOR MSG X

PRESET VAL.:UE FOR TRANSMIT
DELAY TIMER

TPTR ADDR OF LNKBK FOR MSG T
22

NO DATA MESSAGE COUNTER

BABBLING TRIBUTARY
TIMING COUNTER

T/O COUNTER

MK-2721

Figure 5-11

Tributary Status Slot (Sheet 2 of 2)

5-24

APPENDIX A
DDCMP

A.I DDCMP
The Digital Data Communications Message Protocol (DDCMP) provides a data link control procedure
that ensures a reliable data communication path between communication devices connected by data.
links. DDCMP has been designed to operate over full- and half-duplex synchronous and asynchronous
channels in both point-to-point and multipoint modes. It can be used in a variety of applications such as
distributed computer networks, host front-end processors, remote terminal concentrators, and remote
job entry-exit systems.

A.I.I Controlling Data Transfers
The DDCMP message format is shown in Figure A-I. Three control characters are provided In
DDCMP to differentiate between the three possible types of messages:
•
•
•

SOH - Data message follows,
ENQ - Control message follows,
DLE - Maintenance message follows.

Note that the use of a fixed-length header and message size declaration obviates the requirement for
extensive message and header delimiter codes.

SOH

RESPONSE
COUNT FLAG
14 BITS 2 BITS 8 BITS

DATA
SEQUENCE ADDRESS CRC·l
CRC·2
(ANY NUMBER OF 8·BIT
8 BITS
16 BITS
8 BITS
16 BITS
CHARACTERS UP TO 2'4)

MK-2248

Figure A-I

DDCMP Data Message Format

A.I.2 Error Checking and Recovery
DDCMP uses a 16-bit cycle redundancy check (CRC-16) for detecting transmission errors. When an
error occurs, DDCMP sends a separate negative acknowledge (NAK) message. DDCMP does not require an acknowledgement message for all data messages. The number in the response field of a normal
header or in either the special NAK or acknowledge (ACK) control message specifies the sequence
number of the last good message received. For example, if messages 4, 5, and 6 have been received
since the last time an acknowledgement was sent and message 6 is bad, the NAK message specifies
number 5 which says "messages 4 and 5 are good and 6 is bad." When DDCMP operates in full-duplex
mode, the line does not have to be turned around; the NAK is simply added to the sequence of messages
for the transmitter.
When a sequence error occurs in DDCMP, the receiving station does not respond to the message. The
transmitting station detects, from the response field of the messages it receives (or via timeout), that

A-I

the receiving station is still looking for a certain message and sends it again. For example, if the next
message the receiver expects to receive is 5, but receives 6 instead, the receiver does not change the
response field (which contains a 4) of its data messages. The receiver will say, "I accept all messages up
through message 4 and I'm still looking for message 5."

A.t.3

Character Coding
DDCMP uses ASCII control characters for SYN, SOH, ENQ and DLE. The remainder of the message, including the header, is transparent.

A.t.4

Data Transparency
DDCMP defines transparency by use of a count field in the header. The header is of a fixed length. The
count in the header determines the length of the transparent information field, which can be from 1 to
16,383 bytes long. To validate the header and count field, it is followed by a CRC-16 field; all header
characters are included in the CRC calculation. Once validated, the count is used to receive the data
and to locate the second CRC-16, which is calculated on the data field. Thus, character stuffing is
avoided.

A.t.5

Data Channel Utilization
DDCMP uses either full-duplex or half-duplex circuits at optimum efficiency. In the full-duplex mode,
DDCMP operates as two independent one-way channels, each containing its own data stream. The only
dependency is the acknowledgements which must be sent in the data stream in the opposite direction.
Separate ACK messages are unnecessary, therefore, reducing the control overhead. Acknowledgements
are simply placed in the response field of the next data message for the opposite direction. If several
data messages are received correctly before the terminal is able to send a message, all of them can be
acknowledged by one response. Only when a transmission error occurs, or when traffic in the opposite
direction is light (no data message to send), is it necessary to send a special NAK or ACK message,
respectively.
In summary, DDCMP data channel utilization features include:
1.

The ability to run on full-duplex or half-duplex data channel facilities,

Low control character overhead,

No character stuffing,

No separate ACKs when traffic is heavy; this saves on extra sync-characters and intermessage gaps,

Multiple acknowledgements (up to 255) with one ACK, and

The ability to support point-to-point and multipoint lines.

A.2 PROTOCOL DESCRIPTION
DDCMP is a very general protocol; it can be used on synchronous or asynchronous, half-duplex or fullduplex, serial or parallel, and point-to-point or multipoint systems. Most applications involving protocols
are half-duplex or full-duplex transmissions in a serial synchronous mode; that operating environment is
emphasized in the following description.
The header is the most important part of the message because it contains the message sequence numbering information and the character count, the two most important features of DDCMP. Because of
the importance of the header information, it merits its own CRC blockcheck, indicated in Figure A-2 as
CRC-I. Messages that contain data, rather than just control information, have a second section which
contains ariY flufnbef of 8-bit characters (up to a maximum of ! 6,383) and a second eRe (indicated in
Figure A-2 as CRC-2).

A-2

NOTE 1

BE]

RESPONSE SEQUENCE ADDRESS
COUNT FLAG
CLASS
14 BITS 2 BITS
8 BITS
8 BITS
8 BITS

xxxxxxxx
10000001
00000101
ENQ { ACKNOWLEDGEMENT
NEGATIVE ACKNOWLEDGE 00000101

SOH - DATA MESSAGES

BCC HEADER ERROR
BCC DATA ERROR
REP RESPONSE
BUFFER UNAVAILABLE
RECEIVER OVERRUN
MESSAGE TOO LONG
HEADER FORMAT ERROR

REASONS:

ENQ
DLE

XXXXXXXXXXXXXX
CHARACTER COUNT
00000001000000
00000010---------

REPLY MESSAGE
START MESSAGE
START ACKNOWLEDGEMENT
MAINTENANCE MESSAGE

00000101
00000101
00000101
10010000

XX
QS
QS
QS

CRC 1
16 BITS

INFORMATION
ANY NUMBER
OF 8-BIT
CHARACTERS

CRe 2
16 BITS

XXXXXXXX
RESP #
RESP #
RESP #

XXXXXXXX
MESSAGE#
00000000
00000000

XXXXXXXX
ADDRESS
ADDRESS
ADDRESS

00000000
00000000
00000000
00000000

LSTMESS#
00000000
00000000
00000000

ADDRESS
ADDRESS
ADDRESS
ADDRESS

000001
000010
000011
001000
001001
010000
010001

00000011000000
00000110000000
00000111000000
CHARACTER COUNT

QS
11
11
11

NOTES:
1. ONLY THE DATA MESSAGE AND THE MAINTENANCE MESSAGE HAVE CHARACTER COUNTS, SO
ONLY THESE MESSAGES HAVE THE INFORMATION AND CRC2 FIELDS SHOWN IN THE MESSAGE
FORMAT DIAGRAM ABOVE.
2. "RESP #" REFERS TO RESPONSE NUMBER. THIS IS THE NUMBER OF THE LAST MESSAGE
RECEIVED CORRECTLY. WHEN USED IN A NEGATIVE ACKNOWLEDGE MESSAGE, IT IS ASSUMED
THAT THE NEXT HIGHER NUMBERED MESSAGE WAS NOT RECEIVED, WAS RECEIVED WITH
ERRORS, OR WAS UNACCEPTED FOR SOME OTHER REASON. SEE "REASONS."
3. "MESSAGE#" IS THE SEQUENTIALLY ASSIGNED NUMBER OF THIS MESSAGE. NUMBERS ARE
ASSIGNED BY THE TRANSMITTING STATION MODULO 256; I.E., MESSAGE 000 FOLLOWS 255.
4. "LSTMESS#" IS THE NUMBER OF THE LAST MESSAGE TRANSMITTED BY THE STATION. SEE THE
TEXT DISCUSSION OF REP MESSAGES.
5. " ADDRESS" IS THE ADDRESS OF THE TRIBUTARY STATION IN MULTIPOINT SYSTEMS AND IS
USED IN MESSAGES BOTH 'to AND FROM THE TRIBUTARY. IN POINT TO POINT OPERATION, A
STATION SENDS THE ADDRESS "1" BUT IGNORES THE ADDRESS FIELD ON RECEPTION.
6. "Q" AND "S" REFER TO THE QUICK SYNC FLAG BIT AND THE SELECT BIT. SEE TEXT.
MK-2249

Figure A-2

DDCMP Message Format in Detail

A-3

Before the message format is discussed in greater detail, the message sequencing system should be explained because most of the header information is directly or indirectly related to the sequencing operation.
In DDCMP, any pair of stations that exchange messages with each other number those messages sequentially starting with message number one. Each successive data message is numbered using the next
number in sequence, modulo 256. Thus, a long sequence of messages would be numbered 1, 2, 3, ... 254,
255, 0, 1, ... 255. The first message sequence always starts with a number 1, and every sequence thereafter begins with a O. The numbering applies to each direction separately. For example, station A might
be sending its messages 6, 7, and 8 to station B, while station B is sending its messages 5, 6, and 7 to
station A. Thus, in a multipoint configuration where a control station is engaged in two-way communication with ten tributary stations, there are 20 different message number sequences involved - one
sequence for messages from each of the ten tributaries to the control station, and one sequence for
messages from the control station to each of the ten tributaries.
Whenever a station transmits a message to another station, it assigns its next sequential message number to that message and places that number in the sequence field of the message header. In addition to
maintaining a counter for the sequentially numbered messages which it sends, the station also maintains
a counter of the message numbers received from the other station. It updates that counter whenever a
message is received with a message number exactly one higher than the previously received message
number. The contents of the received message counter are included in the response field of the message
being sent, to indicate to the other station the highest sequenced message that has been received.
When a station receives a message containing an error, that station sends a negative acknowledge
(NAK) message back to the transmitting station. DDCMP does not require an acknowledgement for
each message, as the number in the response field of a normal header (or in either the special NAK or
positive acknowledgement message ACK) specifies the sequence number of the last good message received.
When a station receives a message that is out of sequence, it does not respond to that message. The
transmitting station detects this from the response field of the messages which it receives; if the reply
interval expires before the transmitting station receives an acknowledgement, the transmitting station
sends a REP (reply) message. The REP message contains the sequence number of the most recent
unacknowledged message sent to the remote station. If the receiving station has correctly received the
message referred to in the REP message (as well as the messages preceding it), it replies to the REP by
sending an ACK. If it has not received the message referred to in sequence, it sends a NAK containing
the number of the last message that it did receive correctly. The transmitting station then retransmits
all data messages after the message specified in the NAK.
The numbering system for DDCMP messages permits up to 255 unacknowledged messages outstanding; a useful feature when working on high-delay circuits such as those using satellites. However,
the DMV 11 limits the maximum number of unacknowledged messages outstanding to be 127.

A.3

MESSAGE FORMAT

With the above background, it is now time to explore the various DDCMP message formats in full
detail, as shown in Figure A-2. The first character of the message is the class of message indicator,
represented in ASCII with even parity. There are three classes of messages; data, control, and maintenance. These are indicated by class of message indicators SOH, ENQ, and DLE, respectively. The next
two characters of the message are broken into a 14-bit field and a 2-bit field. The 14-bit field is used in
data and maintenance messages to indicate the number of characters that follow the header CRC field
and form the information part of the message. In control messages, the first eight bits of the 14-bit field
are used to designate what type of control message it is; the last six bits are generally filled with zeros.
The exception is in NAK messages where the last six bits are used to specify the reason for the NAK.
The 2-bit field contains the quick-sync and select flags.

A-4

The quick-sync flag is used to inform the receiving station that the message will be followed by synccharacters; the receiver may wish to set its associated synchronous receiver hardware into sync-search
mode and sync-strip mode. This reestablishes synchronization and syncs are discarded until the first
character of the next message arrives. The purpose of this is to permit the receiving station to engage
any hardware sync-stripping logic it might have and prevent it from filling its buffers with sync-characters. The select flag is used to control link management in half-duplex or multipoint configurations
where transmitters need to get turned on and off.
Link management is the process of controlling the transmission and reception of data on links where
there may be two or more transmitters and/or receivers actively connected to the same signal channels.
This is true of half-duplex point-to-point links, as well as full- and half-duplex multipoint links. On halfduplex links, only one transmitter may be active at a time; on full-dupiex links, oniy one siave transmitter may be active on the link at a time.
A station on such a link may transmit when it has been selected or granted ownership of the link. This
ownership is passed by use of the select flag existing in all messages. A select flag set in a received
message allows the addressed station to transmit after completing reception of the message. The select
flag also means that the transmitter ceases transmitting after the message is sent.
The response field contains the number of the last message correctly received. This field is used in data
messages and in the positive and negative acknowledge types of control messages. Its function should be
evident from the preceding discussion of sequence control.
The sequence field is used in data messages and in the REP type of control message. In a data message,
it contains the sequence number of the message as assigned by the transmitting station. In a REP message, it is used as part of the question, "Have you received all messages up through message number
(specify) correctly?"
The address field is used to identify the tributary station in multipoint networks and is used in messages
both to and from the tributary. In point-to-point operation, each station uses an address of 1.
In addition to the positive and negative acknowledgement and REP types of control messages, there are
also start and start acknowledge control messages. These are used to place the station which receives
them in a known state. In particular, they initialize the message counters, timers, and other counters.
The start acknowledge message indicates that this has been accomplished.
Figure A-2 also shows the maintenance message. This is typically a bootstrap message containing load
programs in the information field. A complete treatment of maintenance messages and start-up procedures is beyond the scope of this book.

NOTE
Refer to the DDCMP specification order (AAD599A-TC) for a complete detailed description of
DDCMP.

A-5

APPENDIX B
FLOATING DEVICE CSR AND
INTERRUPT VECTOR ADDRESSES

B.1 FLOATING DEVICE CSR ADDRESSES
UNIBUS and LSI-II addresses, starting at 760010 and continuing through 763776, are designated as
floating device addresses (see Figure B-1). These are used as register addresses for communications (and
other) devices interfacing with the PDP-II system (refer to Table B-1).
NOTE
Some devices are not supported by LSI-II; however,
the same scheme applies. That is, gaps are provided
as appropriate.
The rules for assigning device CSR addresses are as follows:
1.

Device and gap addresses are assigned according to the octal modulus as follows:
a.

Devices with an octal modulus of 4 are assigned an address on a 48 boundary (the two
lowest order address bits = 0).

Devices with an octal modulus of 10 are assigned an address on a 108 boundary (the three
lowest order address bits = 0).

Devices with an octal modulus of 20 are assigned an address on a 208 boundary (the four
lowest order address bits = 0).

Devices with an octal modulus of 40 are assigned an address on a 408 boundary (the five
lowest order address bits = 0).

A gap, assigned according to Rule 1, must be allowed after the last device of each type.

A gap, assigned according to Rule 1, must be allowed for each unused rank on the list if a
device with a higher address is given.

Multiple devices of the same type must be assigned contiguous addresses.

If extra devices are added later to the system, the floating addresses may have to be reassigned
in agreement with Rules 1 through 4.

B-1

777 777

2K
WORDS

DIGITAL EQUIPMENT
CORPORATION
(FIXED ADDRESSES)

DRll-C

770000
767 777

WORDS

USER ADDRESSES

764000
763 777

t
lK
WORDS

FLOATING ADDRESSES
DIGITAL EQUIP CORP (DIAGNOSTICS)

760010
760006
760000
757 777

001 000
000777

VECTORS

FLOATING VECTORS

000 300
000277

48
VECTORS

TRAP & INTERRUPT
VECTORS

000000
MK-21S10

Figure B-1

UNIBUS and LSI-II Address Map

B-2

Table 8-1

Floating Device CSR Address Assignments

Rank

Device

I
2
3
4
5
6
7
8

DJII
DHII
DQII
DUll, DUVII
DUPII
LKIIA
DMCII/DMRII
DZII/DZVI L DZSII,
DZ32
KMCII
RESERVED
VMV21
VMV31
DWR70
RLII, RLVII
LPAII-K
KWII-C
RESERVED
RXII/RX211
RXV I I/RXV21
DRII-W
DRII-B
DMPII
DPVII
ISBII
DMVll
DEUNA
MSCP (disk)
DMF32
KMS11
VSI00
MSCP (tape)
KMV11
DHV11, DHUll
DMZ32
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
ADVII-C
AAVII-C
AXVII-C
KWVII-C
ADVII-D
AAVII-D

9
10
II
12
i3
14
IS
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

Size
(Decimal)

Modulus
(Octal)

4
8
4
4
4
4
4

10
20
10
10
10
10
10 (DMC before DMR)

4
4
4
4
8
4
4
8
4
4
4

10 (DZII before DZ32)
10
10
10
20
10
10 (after first)
20 (after first)
10
10
10 (after first)
(RX 11 before RX211)

4
4
4
4
4
8
4
2
16
6
8
2
8
8
16
16
64
4
8
4
4
4
4
4
4
2
4
4

10
10 (after second)

10
10
10

20
10 (after first)
4 (after first)
40
20
20
4 (after first)
20
20
40
40
lOa
10

20
10
10
10
10
10
10

4
10
10

~OTES:

DZII-E and DZII-F are treated as two DZII devices.

~ote that the units of the size and octal modulus fields are words and bytes, respectively.

B-3

B.2 FLOATING INTERRUPT VECTOR ADDRESSES
Interrupt vector addresses, starting at 300s and proceeding upward to 777 s, are designated as floating
vectors. These are used for communications (and other) devices that interface with PDP-II and VAX-II
systems (refer to Table B-2).
NOTE
Some devices are not supported by LSI-tt; however,
the same scheme applies. Vector size is determined
by the device type.
The rules for assigning vector addresses are as follows:
1.

Each device occupies vector address space equal to the vector size as illustrated in Table B-2.
For example, the DMRII has a vector size of 410 and occupies four vector address locations. If
the DMR 11 vector address was 300s, the next available vector would be 310s.

There are no gaps except those needed to align an octal modulus.

Multiple devices of the same type would be assigned vectors sequentially.

Table B-2

Floating Interrupt Vector Address Assignments

Rank

Device

1
1
2
2
2
2
2
3
4
5
6
7
S
9
10
11
12
13
14
14
14
15
16
17
17
18
19
20
21
22
23
24
25

TU5S
KLII
DLII-A
DLII-B
DLVII-J
DLVl1, DLVl1-F
DPII
DMII-A
DNII
DMI1-BB/BA
DHll modem control
DRII-A
DRII-C, DRVII
PA611 (reader+punch)
LPDll
DT07
DXll
DLII-C
DLII-D
DLI1-E/DLVI1-E
DJ11
DHII
GT40
VSVll
LPSll
DQll
KWII-W, KWVII
DUll, DUVll
DUPII
DV 11 +modem control
LKII-A
RESERVED

Dell

Vector Size
(Decimal)

Modulus
(Octal)

4
4
4
4
4
16
4
4
4
2
2
2
4
4
8
4
4
4
4
4
4
4
4
8
8
12
4
4
4
4
6
4
4

10
10 (See Note 1)
10
10
10
10
10
10
10
4
4
4
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
iO

B-4

Table B-2

Floating Interrupt Vector Address Assignments (Cont)

Rank

Device

26
26
27
28
29
30
31
32
33
34
35
36
37
38
39

DMCII
DMRII
DZII/DZSII/DZVII, DZ32
KMCII
RESERVED
VMV21
VMV31
VTVOI
DWR70
RLII/RLVII
TSII, TU80
LPAII-K
IPl1/IP300
KWII-C
RX1I/RX211
RXV 11 /RXV21
DRII-W
DRII-B
DMPll
DPVII
MLll
ISBII
DMVII
DEUNA/DEQNA
MSCP (disk)
DMF32
KMSll
PCLII-B
VSIOO
MSCP (tape)
KMVII
KCT32
IEUII/IEQII
DHVII, DHUII
DMZ32
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
ADVII-C
AAVII-C
AXVII-C
KWVII-C
ADVII-D
AAVII-D
RESERVED
DRVII-J

40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

Vector Size
(Decimal)

Modulus
(Octal)

4
4
4
4
4
4
4
4
4
2
2
4
2
4
2

10
10 (DMC before DMR)
10 (DZII before DZ32)
10
10
10
10
10
10
4 (after first)
4 (after first)
10
4 (after first)
10
4 (after first)
(RX 11 before RX211)
4
4 (after first)
10
10
4 (MASS BUS device)
10
10
4 (after first)
4 (after first)
4
10
10
4
4 (after first)
10
10
10
10
4
4
1
4
4
4
4 (after first)
4
10
10
0
10 (after first)
10
10
10
4
4

2
2
4
4
2
4
4
12
2
16
6
4
2
2
4
4
4
4
12
12
4
2
2
2
2
2
4
4
0
4
4
4
4
6
32

NOTES:
1.

There is no standard configuration for systems with both DCI1 and TU58.

A KL 11 or DL II, used as the console, uses a fixed vector.

~ote that the size field is in words (two words per interrupt vector), while the modulus field is in

bytes.

B-5

B.3 EXAMPLE OF DEVICE CSR AND INTERRUPT VECTOR ADDRESS ASSIGNMENT
The following example has devices that require device CSR and vector address assignments in the floating
address space. These devices are:

•
•
•

One DUll,
One RL11, and
Two DHUll devices.

Interrupt
Vector
(Octal)

Device

Address
(Octal)

DJ11
DH11
DQ11
DUll
DUll

760010
760020
760030
760040
760050

DUP11
LK11A
DMCll
DZ11
KMC11

760060
760070
760100
760110
760120

Gap for DUP11
Gap for LKIIA
Gap for DMC 11
Gap for DZ11
Gap for KMCll

RESERVED
VMV21
VMV31
DWR70
RLV11

760130
760140
760160
760170
760200

RESERVED Gap
Gap for VMV21
Gap for VMV31
Gap for DWR 70
Gap for RLV11

RLII
LPA11-K
KW11-C
RESERVED
RX11

760210
760220
760230
760240
760250

DR11-W
DR11-B
DMPll
DPV11
DPV11

760260
760270
760300
760310
760320

Gap for DRII-W
Gap for DR11-B
Gap for DMP11
Gap for 1st DPV11
Gap for 2nd DPV11

ISB11
DMV11
DEUNA
UDA50
DMF32

760330
760340
760350
760354
760400

Gap for ISB11
Gap for DMV11
Gap for DEUNA
Gap for UDA50
Gap for DMF32

KMS11
VS100
RESERVED
KMVII
DHUll

760420
760440
760444
760460
760500

320

Gap for KMS 11
Gap for VSIOO
RESERVED gap
Gap for KMV11
1st DHU11

DHUll
DHU11

760520

330

Comment
Gap for DJ11
Gap for DH11
Gap for DQ11

300
Gap for 2nd DU 11

310
Gap for LPA11-K
Gap for KW11-C
RESERVED gap
Gap for RXll

2nd DHTJll
Gap for 3rd DHUl1

760540

B-6

The first floating address is 760010. As the DJII has a modulus of 108, its gap can be assigned to 760010.
The next available location becomes 760012.
As the DHII has a modulus of 208, it cannot be assigned to 760012. The next modulo 20 boundary is
760020, so the DHII gap is assigned to this address. The next available location, therefore, is 760030.
A DQII has a modulus of 108, it cannot be assigned to 760022. Its gap, therefore, is assigned to 760030.
The next available location becomes 760032.
A DU 11 has a modulus of 108; it cannot be assigned to 760032. It, therefore, is assigned to 760040. As
the vector size of the DUll is four words, the next available address is 760050.
There is no second DU 11, so a gap must be left to indicate that there are no more DU II devices. As
760050 is on a 108 boundary, the DUll gap can be assigned to this address. The next available address is
760052.
and so on ...

B-7

APPENDIX C
MODEM CONTROL REGISTER FORMATS

C.I MODEM CONTROL REGISTER FORMATS
The modem signals made available by the DMVII can be examined or modified by the user program if
needed. This supplies the flexibility needed to meet the various modem interface requirements of different countries.
READ MODEM STATUS

BSEL4:
Bit

Name

Description

CARRIER

Received line signal detector, commonly referred to as carrier detect, indicates that there is an appropriate audio tone being received from the remote modem. Typically, in full- and half-duplex applications, carrier detect is on whenever the
communications line is intact and the remote modem has the signal request to send asserted (the modem is transmitting). This
signal is also applicable to the DMVl1 integral modem.

NOT USED

ALWAYS READ AS ZERO.

CLEAR TO SEND

This signal is generated by the local modem to indicate whether
or not it is ready to transmit data. Clear to send is the local
modem's response to the asserting of request to send. This signal
has a slightly different meaning with different modems. With
some modems it indicates that the carrier is being received from
the remote modem, and, therefore, is an indication that a suitable
communications channel exists.

MODEM READY

This signal indicates that the modem is ready to operate. The ON
condition indicates that the local modem is connected to the communications line and is ready to exchange further control signals
with the DMVII. The OFF condition indicates that the local
modem is not ready to operate. This signal, when implemented by
the modem, is used by the DMVII to detect either a power-off
condition or a cable-related modem malfunction.

HALF-DUPLEX

This signal, when asserted, indicates that the DMVII is in the
half-duplex mode. This means that the DMVII is connected to a
communications line designed for transmission in either direction, but not in both directions simultaneously. When cleared, it
implies full-duplex operation which is two-way independent transmission in both directions.
C-l

Bit

Name

Description

REQUEST TO SEND

This signal serves to control the data channel transmit function of
the local modem, and on a half-duplex channel, to control the direction of data transmission of the local modem. On a fuii-dupiex
channel, the ON condition maintains the modem in the transmit
mode, and the OFF condition maintains the modem in the nontransmit mode. On a half-duplex channel, the ON condition
maintains the modem in the transmit mode and inhibits the receive mode. The OFF condition maintains the modem in the receive mode. A transition from OFF to ON instructs the modem to
enter the transmit mode. The modem responds by taking such action as may be necessary and indicates completion of such actions
by asserting clear to send, thereby, indicating to the DMVll that
data may be transferred across the communications channel. A
transition from ON to OFF instructs the modem to complete the
transmission of all data that was previously transferred to the
modem and then assume a nontransmit or receive mode, whichever is appropriate. The modem responds to this instruction by
turning OFF the signal clear to send when it is again prepared to
respond to a subsequent ON condition of request to send.

DATA TERMINAL
READY

This signal controls the switching of the local modem to and from
the communications line. When asserted, this signal serves to inform the local modem that the DMVll is ready to operate. This
signal also prepares the modem for connection to the communications line and maintains this connection as long as it is ON.
When turned OFF, this signal causes the local modem to disconnect after all data previously transferred to the modem has
been transmitted. This signal can be used by the local modem to
detect a power-off condition in the DMVll or a cable-related
modem malfunction.

RING

This signal indicates whether an incoming call signal is being received by the local modem. When ON, this signal indicates that
an incoming call (ringing) signal is being received by the local
modem. The ON state of ring must appear approximately at the
same time as the ON segment of the ringing cycle (during rings)
on the communications line. The OFF condition must be maintained during the OFF segment of the ringing cycle (between
rings) and at all other times that ringing is not being received.
This signal is not affected by the state of data terminal ready.

READ MODEM STATUS
BSEL5

Bit

Name

Description

MODE

This bit indicates the operational mode of the line unit. A one indicates character-oriented protocol operation, and a zero indicates bit-oriented protocol operation. The DMVll initializes
this bit to one.

C-2

Name

Description

NOT USED

ALWAYS READ AS ZERO.

TEST MODE

This signal indicates whether or not the local modem is in a test
condition. (This signal applies only to modems that support this
feature.) When in the ON condition, this signal indicates to the
DMVII that the local modem has been placed in a test condition.
The ON condition can also be in response to either local or remote activation by means of any other modem test condition. Activation of a telecommunications network test condition (for exampie, faciiity loop back) that is known to the modem can also
cause this signal to be ON. In the OFF condition, this signal indicates that the modem is not in the test mode and is available for
normal operation.

NOT USED

AL WAYS READ AS ZERO

NOT USED

AL WAYS READ AS ZERO

NOT USED

ALWAYS READ AS ZERO

NOT USED

AL WAYS READ AS ZERO

NOT USED

AL WAYS READ AS ZERO

Bit

WRITE MODEM CONTROL
BSEL4

Bit

Name

NOT USED

Description

SELECT STANDBY

Defaulted to 0 by DMY 11 hardware.

MAINTENANCE
MODE 2

Defaulted to 0 by DMY 11 hardware.

MAINTENANCE
MODEl

Defaulted to 0 by DMY 11 hardware.

HALF-DUPLEX

The DMY 11 uses this bit to place the line unit into the half-duplex mode. The user program cannot set or clear this bit. The
D MY 11 can change line characteristics only through the mode
definition command. The DMY 11 is equipped with a software interlock that prevents simultaneous transmission and reception
when in the half-duplex mode. While the transmitter is transmitting, the receiver is disabled from receiving data via a hardware interlock.
I

SELECT
FREQl.JENCY

This signal is used to select the transmit and receive frequency
bands of a modem. In the ON condition, the higher frequency

C-3

Bit

Name

Description
band is selected for transmission to the communications channel,
and the lower freauencv band is selected for receotion from the
communications chann~l. When OFF, the lower f~equency band
is selected for transmission to the communications channel, and
the higher frequency band is selected for reception from the communications channel.
NOTE
The modem, if it supports select frequency, must be
set up to ignore this signal from DMVl1.

DATA TERMINAL
READY

This signal controls switching of the local modem to and from the
communications line. When asserted, this signal serves to inform
the local modem that the DMVll is ready to operate. This signal
also prepares the modem for connection to the communications
line and maintains this connection as long as it is ON. When
turned OFF, this signal causes the local modem to disconnect after all data previously transferred to the modem has been transmitted. This signal can be used by the local modem to detect a
power-off condition at the DMVll or a cable-related modem
malfunction.

NEW SIGNAL

This signal determines whether or not the local modem will rapidly respond to new data on the communications line. This signal is
used at control stations in multipoint networks where the remote
modems operate in switched-carrier mode. This incoming signal
to the control station appears as a series of short message bursts
transmitted by each tributary as it responds to the poll from the
control station. In order to permit rapid accommodation to signals from several tributaries appearing in quick succession, the
control station informs the local modem when a new signal is
about to begin by asserting polling for a brief interval. For synchronous systems, clock timing on the incoming message varies
from message to message because the remote modems are in no
way synchronized to each other. If the time interval between messages is too short, the clock holdover after the end of one message
may preclude rapid synchronization on the following message.
The use of this signal allows the control station to reset the
modem receiver timing recovery circuit, enabling it to respond
more quickly to the line signal present after polling has been
turned OFF. This signal applies only to modems that support polling.

C.2

RS-449 VERSUS RS-232-C

The most common interface standard in use during recent years is RS-232-C. However, when used in
modern communications systems it has critical limitations; the most serious being speed and distance.
For this reason, the interface standard RS-449 was developed to replace RS-232-C. This standard maintains a degree of compatibility with RS-232-C to accommodate an upward transition to RS-449.
The most significant difference between RS-449 and RS-232-C is the electrical characteristics of signals used between the data communications equipment (DCE) and the data terminal equipment
C-4

(DTE). The RS-232-C standard specifies only unbalanced circuits, whereas, RS-449 specifies both balanced and unbalanced circuits. The specifications for these two circuit types supported by RS-449 are
contained in EIA standards RS-422-A for balanced circuits and RS-423-A for unbalanced circuits.
These new standards permit greater transmission speeds and allow greater distance between the DTE
and DCE. The maximum transmission speeds supported by RS-422-A and RS-423-A specified circuits
vary with circuit length. The normal transmission speed limits are 20K bls for RS-423-A at 61 m (200
feet) and 2M bls for RS-422-A also at 61 m (200 feet). These normal transmission speeds can be varied
by tradeoffs between speed and distance.
Another major difference between RS-449 and RS-232-C is the specification of two new connectors to
accommodate the leads required to support additional circuit functions and the balanced interface circuits. One connector is a 37-pin cinch used to accommodate the majority of data communications applications. The other is a 9-pin cinch for applications requiring secondary channel functions. Some of the
new circuits implemented by RS-449 support local and remote loopback testing and standby channel
selection.
The transition from RS-232-C to RS-449 will not happen immediately. Therefore, applications that require connection between RS-232-C and RS-449 interfaces must adhere to the limitations of RS-232-C,
which specifies a normal transmission speed of 20K bls at a maximum distance of 15.2 m (50 feet).
DMV11 does not support RS-422-A balanced circuits.

C-5

APPENDIX D
MODEM CONTROL
D.I MODEM CONTROL
There are two ieveis of modem control available to the DMVII. The first level is provided by the hardware, and the second by the D MV 11 microcode.
D.I.I Hardware Modem Control
The DMVII provides the following modem control function:
•

Prevention of simultaneous transmission and reception in half-duplex mode.

Half-Duplex Mode - When set, HALF-DUPLEX specifies that the DMVII is in the half-duplex mode.
In half-duplex mode, a hardware interlock prevents the DMVII from transmitting and receiving simultaneously.
NOTE
This hardware lockout prevents the DMVII from
being used in the half-duplex mode on a full-duplex
modem with the continuous carrier option installed.
D.I.2 Modem Control Implemented by the DMVII Microcode
The modem control signals implemented by the DMVII are:
•
•
•
•
•

Modem ready (data set ready),
Request to send/clear to send,
Carrier,
Data terminal ready, and
Auto answer.

Each of these signals are outlined in Table D-1.
Once modem ready goes ON, the DMVII reports any transition from ON to OFF to the user program
by issuing a control response containing the code for the system-event modem disconnect. The microcode tests that modem ready is OFF for 10 ms. Transmission is initially inhibited by the microcode by
interlocking the signals modem ready and request to send.
Whenever the signal carrier detect is dropped by the modem for greater than 1.28 seconds, the user
program is notified by a control response containing the code for the system event modem carrier loss.
Diagrams are used in the discussion of modem control functions. Refer to Figure D-1 as an aid in interpreting these diagrams. The flow depicted by the diagrams (Figures D-2 through 0-8) describes the processing of EIA modem control signals by the DMV11. Each diagram represents a serial flow for a specific modem control function. However, the functions performed, as represented by each diagram, are
performed in parallel. The readable and writeable modem signals listed on the diagram for modem status can be read and written through the control command using the request keys read modem status
and write mode control.

D-l

Table D-l

DMVll Modem Control Functions

Signal

Description

Data Set ReadyModem Ready:

Software interlock prevents the DMVII from transmitting if DSR is not
returned. If DSR drops (meaning that it once was asserted) for a period
of 10 ms, the transmitter and receiver are resynchronized, the transmitter
and receiver sections of the microcode are reset to the idle state to allow
the user to return buffers, DTR is then dropped to clear the line (see
DTR for reasserting conditions), and the user is then notified of the DSR
drop via a control-out for disconnect.
Software interlock preventing the DMVII from transmitting if DSR is
not returned: If the DMVII has been instructed by the user to start up
the communications line, and DSR is not asserted, the D MV 11 does not
transmit. There is no timer started for the first assertion of DSR. It is the
responsibility of the user to ensure that the modem is plugged in. Also, if
the modem is a dial-up modem, the user should make sure that the number is dialed. In most cases the start command is issued with the intent of
waiting for an incoming call. In this case, the timer value is arbitrary so
that it has been left up to the user software to determine this timeout. If
data terminal ready (DTR) is not asserted because of a past error condition that caused the dropping of DTR (that is, disconnect), the user program may assert DTR via the write modem command to enable transmission.

Request to Send/
Clear to Send:

For all applications: Before RTS is asserted (if already asserted this is
bypassed) CTS is checked for the "ON" condition. If CTS is "ON", a
10-20 ms timer is started while waiting for CTS to drop. If CTS does not
drop within the timer period, constant CTS is assumed and RTS is set.
For all applications: Software interlock prevents transmission if CTS is
not returned. IF CTS is not returned within 30 seconds (plus or minus 10
ms), a disconnect control-out is queued with a CTS failure code in
BSEL 7. The transmitter and receiver are resynchronized, the transmitter
and receiver sections of the microcode are reset to the idle state to allow
the user to return buffers, and DTR is then dropped to clear the line. (See
DTR for reasserting conditions).
For all applications: During the time that RTS is set, every 10 ms CTS is
checked for the "ON" condition. If CTS stays in the "OFF" condition for
30 seconds (plus or minus 10 ms), a disconnect control out is queued with
a CTS failure code in BSEL 7. The transmitter and receiver are resynchronized, the transmitter and receiver sections of the microcode are
reset to the idle state to allow the user to return buffers, and DTR is then
dropped to clear the line. (See DTR for reasserting conditions).
For all half-duplex applications: The setting of request to send is "ANOED" with the half-duplex bit in the hardware to "blind" the receiver
when transmitting.

0-2

Table D-I

DMVII Modem Control Functions (Cont)

Signal

Description

Carrier:

Software interlocks prevent transmission in half-duplex if carrier is in the
"ON" condition. This prevents the DMV II from running half-duplex on
four-wire constant carrier modems.
For all applications: Hardware interlock of carrier and the receiver clock
stop the USYRT from receiving if carrier were to drop in the middle of a
mf"~~~Of"

···~~~-o~·

For all applications: If carrier "drops" while the DMVII is in the process
of receiving the carrier, the loss timer is started. If the carrier loss timer
expires (1.28 second interval), the user is notified via a control-out for
carrier loss. The receiver is then resynchronized and the receiver microcode is reset to the waiting state for the next message. If the carrier loss is
less than 1.28 seconds (carrier is reasserted before the timeout), the message being received is allowed to finish. If CRC errors are detected (normal case), the protocol recovers from the failure.
Data terminal ready:

DMVII clears DTR on a power-up bus initialization, and a master clear.
This is a hardware function. DTR is not gated from the interface drivers
when the DMVII is placed in loopback mode. DTR is monitored by diagnostics running in internalloopback to ensure that the microcode does not
set it.
When DTR is dropped because of errors, it is only reasserted if any of the
following conditions exist: auto answer is enabled or remote load detect is
enabled. The code is in the process of power-on boot or request boot.

Auto Answer:

This option is switch selectable. If enabled, the DMVII asserts DTR and
waits for modem ready (DSR). Because of the difference between
modems in the U.S. and other countries, ring is not used as an indication
that an incoming call has been established. As it stands, DSR is the indication that the call has been established. If a valid DDCMP message is
not received within 30 seconds (plus or minus 10 ms) after a connection is
established, DTR is dropped (hang up the phone). The connection is considered to be established on assertion of carrier or clear to send. The
transmitter and receiver are resynchronized, the transmitter and receiver
sections of the microcode are reset to the idle state, and DTR is then reasserted after DSR drops (or in 10 seconds whichever comes first). In this
case the user is not notified of the cancelled call. An internal counter is
incremented to log the incoming calls (latches at 256) and is available for
reading by the user program.

D-3

CONDITIONS TO BE SATISFIED. IF CONDITIONS ARE NOT
MET SERIAL FLOW DOES NOT CONTINUE.

ACTIONS PERFORMED BY DMV11.

C_)

ENTRY OR EXIT SYMBOLS

MK·2657

Figure D-l

Flow Diagram Symbology

D-4

POWER ON

---'T""""---

SYSTEM
IN ITIALIZATION

[2.4]

DEVICE
MASTER CLEAR

[2.4]

[2.5]

POWER ON
BOOT ENABLED
(SWITCH)
USER ISSUES
MODE DEFN
COMMAND

MODE DEFINED
IN SWITCHES

BOOT
BIT SET

[2.2]

SET DTR
SET CALTMR
ON

"-../

[2.6]

[2.3]
A
USER REQUEST
MODEM STATUS
READ/WRITE

CALTMR

= ON

DSR

[2.2]

= ON

= ON
= ON

DSR
CD

[2.1]

SCAN FOR
REMOTE
LOAD
MESSAGE

VALID
MESSAGE

DSR
ON TO
OFF FOR

MESSAGE TO
BE SENT

10mSEC

P/MOP = ON

P/MOP = OFF

NOTIFY USER OF
DSR DROP
DISCONNECT
(CONTROL RESPONSE)

TRANSMIT

NOTES:
[2.1] REMOTE LOAD DETECT IS A MAINT. DDCMP MESSAGE INITIATING A DOWN LINE LOAD.
[2.2] CALTMR • (CALL TIMER): USED TO DETERMINE IF VALID MESSAGE IS RECEIVED. "ON" INDICATES TIMER
RUNNING.
[2.3] P/MOP • PRIMARY MAINTENANCE OPERATION PROTOCOL. REQUESTING REMOTE LOAD.
[2.4] RUN COMPLETE MICRODIAGNOSTICS (MICROPROCESSOR AND LINE UNIT)
[2.5] HARDWARE FUNCTION
[2.6] INVOKE PRIMARY MOP BOOT (BIT FIVE. BSEL 1)
MK·2705

Figure 0-2

Modem Control (Start)

D-5

(

TRANSMIT)

______

HALF-DUPLEX

I
RECEIVER NOT
ACTIVE

t
FULL-DUPLEX

~*~

NO LINE ERRORS
ENCOUNTERED

~t~_____
LINE ERRORS
ENCOUNTERED

·1
CD = OFF

CWTIMR
=0

•

CTS = 0

CTSTMR = 0

NO TIFY USER OF
ST REAMING
ST ATION
CTS=ON

•

CTS TIMR=O

CD = OFF

RTS=OFF

RTS = ON

I
CTS=OFF

CTS TMR=O

END OF TRANS

FDX

CTS=OFF

HDX

NOTES:
[3.1) CWTIMR-- CARRIER WAIT TIMER. IT DETECTS THE CONDITION WHERE THE LINK WAS NOT RELINQUISHED IN
TIME BYTHE REMOTE END.
[3.2] CTSTMR -- CLEAR TO SEND TIMER. TIME CLEAR TO SEND GOING AWAY WHEN DROPPING RTS BECAUSE OF LINE
ERRORS. FALL-OUT COVERS CONDITION OF CONSTANT CTS MODEMS.
[3.3) IN FULL DUPLEX MODE -- DMP11 ASSERTS RTS CONSTANTLY. RTS IS DROPPED ONLY WHEN THERE ARE LINE
ERRORS.
[3.4) SOFTWARE INTERLOCK· CONDITION IS SWITCH SELECTABLE FOR CONSTANT CTS MODEMS.
IIIK·27011

Figure 0-3

Modem Control (Transmit)

0-6

(

TRANSMIT 2 )

I
LESS THAN 24 REQUEST
REMOTE PROGRAM LOAD
MESSAGES SENT

24 REQUEST REMOTE PROGRAM
LOAD MESSAGES SENT

TIMER-3 SEC

TIMER = 0
TIMER = 0

MK-2703

Figure 0-4

Modem Control (Transmit 2)

0-7

(

RECEIVE)

HALF·DUPLEX

FULL·DUPLEX

t
TRANSMITTER NOT
ACTIVE
IN HALF DUPLEX, LINE UNIT
PROVIDES INTERLOCK TO
ENABLE RCV CLOCK ONLY IF
TRANSMITTER IS IDLE.
(RTS -OFF)

CD- ON
SYNC'ED ON NEW
FRAME

_ _ _'''___ _ CD DROPPED IN THE
MIDDLE OF DATA
CD = OFF
---~-- STREAM
RESET CDTIMR
TO 1.28 SEC

CDTIMR = 0

CD= ON

NOTI FY USER OF
CARRIER LOSS
(CONTROL RESPONSE)
END OF
RECEIVE

MK·2704

Figure 0-5

Modem Control (Receive)

D-8

(

[6.1]

MOO STAT)

WRITE MODEM
STATUS

READ MODEM
STATUS

[6.2]

~--------------~.~~~4~--------------~
[6.2]
WRITEABLE MODEM SIGNALS:

[6.1]
READABLE MODEM SIGNALS:
CARRIER
CLEAR TO SEND
MODEM READY (DSR)
HALF DUPLEX
REQUEST TO SEND
DATA TERMINAL READY
RING
TEST MODE

DATA TERMINAL READY

MK·2702

Figure 0-6

Modem Control (Modem Status)

D-9

CALL TIMER = 0

VALID MESSAGE
RECEIVED FOR
THIS STATION

CLEA~

DTR

SET CALTMR
= OFF

RESET RECEIVER
AND
TRANSMITTER

TIMER-10 SECI

TIMER = 0

NOTE: CALTMR = ON
MK-1967

Figure 0-7

Modem Control (Call TiIlH:r)

D-I0

(SHUT DOWN)

CLEAR DTR
AND RTS

RESET RECEIVER
AND TRANSMITIER

BOOTING

REMOTE LOAD
DETECT

CALL TIMR=ON

TIMR+-10 SEC

I
I

TIMR=O

,
SET DTR

A
MK·2tS15l5

Figure D-8

Modem Control (Shutdown)

D-ll

APPENDIX E
QMA DMVll
OPTION CONFIGURATIONS

E.I INTRODUCTION
This appendix lists the option variations and cabinet kits available for the QMA DMVll Synchronous
Controller module. The method for assigning DMV 11 option designations is also described.
The communications option designations enable DIGITAL customers to obtain communication options
that are custom-tailored to their particular needs. FCC regulations require that all system cabinets
manufactured after October 1, 1983, and intended for use in the United States, be designed to limit
electromagnetic interference (EMI). Since both shielded and unshielded cabinets exist in the field, Digital
Equipment Corporation provides separate communication options for each cabinet type.
E.2 OPTION DESIGNATION CONVERSION
Since former DMVII configurations are discontinued or changed to MAINTENANCE ONLY status,
the new option designations must be used to obtain the necessary equipment. Table E-I can be used to
determine which communication option designations to use when designing or expanding upon a computer
system.
Communication options may be obtained by customers either at the time a system is purchased or as an
upgrade to an existing system in the field.
E.2.1 Installed Option
An add-on option is identified by two option designations: a base option designation and a cabinet kit
designation. When these designations are specified (see Table E-l), the appropriate module(s), cable(s),
and distribution panels are installed in the particular system being constructed.
E.2.2 Add-On Option
An add-on option is identified by the same method as the installed option (see Table E-I).
E.2.2.1 Base Options - The base option designation specifies the electronic module(s) and option
documenta tion.
E.2.2.2 Cabinet Kits - The cabinet kit designation specifies the internal cable, the distribution panel, and
an adaptor bracket for installing the distribution panel in a non-FCC compliant cabinet may be included.
External cables needed to connect to a modem or other external device are usually not included.
E.3 OPTION CONFIGURATION SUMMARY
Communication option designations ensure that the proper cable(s), distribution panels, and adaptor
brackets (if necessary) are shipped with each base option.

E-l

Table E-l

OLD OPTION

Option Compatibility Cross-Reference

EQUIV ALENT NEW OPTION

Base Option

Cabinet Kit

DMVII-AA
(RS-232-C)

DMVII-M

CK-DMVII-A(*)

DMVII-AA
(RS-423-A/449)

DMVII-M

CK-DMVII-F(*)

DMVII-AB
(V.35)

DMVII-M

CK-DMVII-B(*)

DMVII-AC
(Integral Modem)

DMVII-N

CK-DMVII-C(*)

NOTE
The last character of the cabinet kit (*) varies
depending on which kit is required (refer to
Table E-3).

Communication options may be obtained by customers either at the time a system is purchased (a factoryinstalled system option) or as an upgrade to an existing system in the field (a field upgrade).
The basic designations refer to:
•
•

Base options
Cabinet kits

Base options and cabinet kits can be factory installed or ordered as upgrades to systems already existing in
the field. A base option and cabinet kit together make a complete field upgrade option (that is; a base
option designation and cabinet kit designation must both be specified to obtain a complete field upgrade).
NOTE
A field upgrade option alone does not make an
unshielded cabinet FCC compliant. Shielded cabinets
are specially constructed to limit EMI.

E-2

E.3.1

Base Option Designations

Base option designations provide the following information (Figure E-I):

DMV11-M

--_-It 1

THE DEVICE NAME (THAT IS, DMV11)
SPECIFIES A BASE OPTION (TABLE E-2)

Figure E-l

Table E-2

Electrical and Mechanical Interface Type

Character

Interface Type

RS-232-C (with full modem control)
V.35
Integral modem
RS-423-A/449
Base option

C
F
M,N

E.3.2

Base Option Designation

Cabinet Kit Designations

Cabinet kits enable customers to custom-tailor communication options to their particular cabinet. Cable
lengths, distribution panels, and method of installation may vary depending on the cabinet kit obtained.
Cabinet kits are individually tailored to specific cabinet types. This enables customers to install communication options in both shielded (FCC compliant) and unshielded (non-FCC compliant) cabinets.
Cabinet kits include:
•
•
•

Internal cable(s).
Distribution panel.
An adaptor bracket (if necessary).

The internal cable connects the module to the distribution panel which is installed in an I/O bulkhead.
Typically, external cables needed to connect to a modem or other external device are not supplied with the
option and must be ordered separately.

E-3

Cabinet kit designations have two characters following the device name (Figure E-2).

, ,,
T I JI

CK-DMV11-FA
SPECIFIES CABINET KIT
THE DEVICE NAME (THAT IS, DMV11)
THE INTERFACE TYPE IDENTIFIER (TABLE E-2)
THE CABINET IDENTIFIER * (TABLE E-3)

*THE CABINET IDENTIFIER INDICATES WHICH CABLE
LENGTHS ARE SUPPLIED WITH THE CABINET KIT.
TK-11342

Cabinet
Identifier

Figure E-2

Cabinet Kit Designation

Table E-3

Cabinet Kit Components

Component Parts Supplied

Letters Indicate
Shielded Cabinets

A
B

c
F

•
•
•
•
•
•
•
•

A 53.34 cm (21 in) internal cable (see Note 1)
A distribution panel (PDP-II /23S) (see Note 2)

•
•

A 3.05 m (10 ft) internal cable/panel (see Note 1)

A 30.48 cm (12 in) internal cable (see Note 1)
A distribution panel (Micro-II) (see Note 2)
A 76.20 cm (30 in) internal cable (see Note 1)
A distribution panel (PDP-II /23+) (see Note 2)
A 91.44 cm (36 in) internal cable (see Note 1)
A distribution panel (VAX-II /725, PDP-II /84) (see Note 2)

Numbers Indicate
Unshielded Cabinets
2

A 7.62 m (25 ft) interconnection cable
1.

NOTE
Integral modem versions use 70-18250/
70-20862 cable/panel; V.35 versions use 7020861 cable/panel; all others use BC08S cable.
RS-232-C version uses 70-20863 panel;
RS-423-A/449 version uses 70-20864 panel

E-4

E.4 DMVll OPTION CONFIGURATIONS
Table E-4 provides a reference to other option configurations that are available for the DMV 11 Synchronous Controller beginning October 1, 1983.
Table E-4

OMVll-M (BASE
OPTION USEO IN
THE FOLLOWING
CABINET KITS

DMVll Option Configurations

RS-232-C APPLICATIONS
1

• CK-OMVll-AA

• CK-OMVll-AB

• CK-OMVll-AC
• CK-OMV11-A2

• CK-OMVll-AF
RS-423/RS-449
APPLICATIONS
1

• CK-OMVll-FA

• CK-OMVll-FB

• CK-OMV11-FC
• CK-OMV11-F3

• CK-OMV11-FF
V.35 APPLICATIONS
• CK-OMV11-BA

• CK-OMVll-BB

• CK-OMVll-BC

1
1

• CK-OMV11-B3

• CK-OMV11-BF
OMV11-N (BASE OPTION
USEO IN THE FOLLOW1NG CAB1NET KITS)

INTEGRAL MOOEM
APPLICATIONS
• CK-OMV11-CA
• CK-OMVll-CB
• CK-OMV11-CC
• CK-OMV11-C3
• CK-OMV11-CF
MKV86-1684

E-5

Table E-4

DMVll Option Configurations (Cont)

DMVll-M (BASE
OPTION USED IN
THE FOLLOWING
CABINET KITS)
RS-232-C APPLICATIONS
• CK-DMV11-AA,
• CK- DMVll-AB
• CK-DMVll-AC
• CK-DMVll-A2
• CK-DMVll-AF
RS-423/RS-449
APPLICATIONS
• CK-DMVll-FA
• CK-DMVll-FB
• CK-DMVll-FC
• CK-DMVll-F3
• CK-DMVll-FF
V.35 APPLICATIONS
• CK-DMVll-BA
• CK-DMVll-BB
• CK-DMVll-BC

• CK-DMV11-B3
• CK-DMVll -BF
DMV11-N (BASE OPTION
USED IN THE FOLLOWING CABINET KITS)
INTEGRAL MODEtv:'
APPLICATIONS
• CK-DMVll-CA

• CK-DMV11-CB

• CK-DMVll-CC

I I I 1 Ii 1 Ii 1 Ii 1 !

• CK-DMV11-C3

I ! I I I

• CK-DMV11-CF

1
MKV86-0884

E-6

Digital Equipment Corporation. Bedford, MA 01730